WO2024252277A1

WO2024252277A1 - An agricultural biostimulant/biofertilizer composition

Info

Publication number: WO2024252277A1
Application number: PCT/IB2024/055445
Authority: WO
Inventors: Dhirendra Kumar; Rekha PUTTASWAMY; Jayalakshmi PALAKURI
Original assignee: Natural Plant Protection Ltd
Current assignee: Natural Plant Protection Ltd
Priority date: 2023-06-05
Filing date: 2024-06-04
Publication date: 2024-12-12
Anticipated expiration: 2025-12-05
Also published as: AR132861A1

Abstract

The present disclosure relates to an agricultural composition comprising a biological extract. In particular, the present disclosure relates to an agricultural composition comprising yeast extracts. The present disclosure also relates to methods of making the yeast extracts, methods of making the composition and uses thereof. More particularly, the present disclosure relates to a biostimulant/biofertilizer composition.

Description

“AN AGRICULTURAL BIOSTIMULANT/BIOFERTILIZER COMPOSITION”

Field of invention:

The present disclosure relates to an agricultural composition comprising a biological extract. In particular, the present disclosure relates to an agricultural composition comprising yeast extracts and methods of preparing the same. More particularly, the present disclosure relates to a biostimulant/biofertilizer composition.

Background:

Y east extracts — the interior components of the yeast cell — are rich in a wide variety of amino acids, which can complex with trace minerals for improved nutrient bioavailability. Yeast extract is also known to be rich in nucleotides, sugars and a variety of trace minerals and metabolites apart from amino acids and proteins.

Yeast-based biostimulants such as yeast extracts, yeast-derived amino acids and fertilizers have been used to improve plant growth and yield, improve stress tolerance, and reduce the effects of abiotic stresses in plants. Recently, the PCT publication WO2022184820A1 teaches reducing the effects of abiotic stress in a plant and/or a plant part; and/or increasing the tolerance to abiotic stress of a plant and/or a plant part; and/or increasing biomass or yield of a plant and/or a plant part under abiotic stress; wherein said method comprises contacting the plant and/or the plant part or soil with a composition comprising a yeast-derived material. The yeast derived material may be a yeast hydrolysate, particularly obtained using an alkaline hydrolysis method.

Humic and fulvic acids which are organic acids found naturally in soil from the decomposition of plant, animal and microbial residues. Fulvic and humic acid increase soil water retention. They also help to filter out toxins and heavy metals, increasing the health of the plant and its produce. These contribute to soil fertility, root nutrition, nutrient uptake, increases chlorophyll, and photosynthesis etc.

Sabreen Kh. A. Ibraheim (“Effect of Foliar Spray With Some Biostimulants on Growth, Yield and Seeds Quality of Pea Plants Grown In Sandy Soil”, Journal of Applied Sciences Research (2014), 10(5), 400-407) compared the effects of foliar spraying of pea plants with yeast extract with that of biostimulant Mega Power - X comprising humic acid, fulvic acid, free amino acids, chelated minerals and potassium citrate.

Despite the knowledge about yeast-based biostimulants, there still exists immense potential to optimize and develop new compositions based on yeast extracts which will improve yield significantly, reduce the deleterious effects of biotic and abiotic stresses, and increase the tolerance of plant towards these stresses. There also exists a need for new and innovative biostimulant compositions which also function as a biofertilizer. There exists an unmet need in the art to optimize the process of production of yeast-based plant growth promoter which will provide enhanced efficacy as a biostimulant and a biofertilizer. Moreover, there still remains a need for yeast extract-based compositions which can be applied in low doses to generate higher yield, growth, and stress tolerance in plants.

The present disclosure aims to provide compositions and methods that are markedly different from such compositions known in the prior art and provide new and effective ways of improving yield and mitigating biotic and abiotic stress. The inventors of the present disclosure herein aim to provide a yeast-based agricultural composition which benefits the plant in terms of yield, growth, and stress tolerance, even at lower doses. The present disclosure also aims to provide an effective method of obtaining a functionally effective yeast extract which contributes to the overall efficacy of the agricultural compositions mentioned herein.

Summary:

An aspect of the present disclosure provides an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; and c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof.

An aspect of the present disclosure provides an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients, or micronutrients.

In an embodiment, the yeast-based plant growth promoter is a yeast extract, an inactive yeast, yeast cell walls or yeast cell-wall derivatives. In an embodiment, the yeast extract is a cell-free fermentation extract, cell-free spent media, yeast hydrolysate, cell -free yeast hydrolysate, yeast autolysate, cell-free yeast autolysate, fermentation extract comprising live or dead cells, spent media comprising live or dead cells, or an unfdtered extract comprising lysed cells and cell debris.

In an embodiment, the yeast-based plant growth promoter is a yeast extract, obtained through an alkaline hydrolysis, an enzymatic hydrolysis, an acid hydrolysis, a physical treatment, a mechanical treatment, or combinations thereof. Preferably, the yeast extract is obtained through a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis.

In an embodiment, yeast-based plant growth promoter is characterized by presence of amino acids in the range of about 1% w/w to about 20% w/w of the total weight of the yeast-based plant growth promoter. In an embodiment, the yeast-based plant growth promoter further comprises carbohydrates, sugars, metabolites, and moisture.

In an aspect, there is provided a process of preparing the yeast-based plant-growth promoter, in particularly a yeast extract. In an embodiment, said yeast extract is obtained by a process comprising the following steps: i) providing an inoculum of yeast; ii) subjecting the yeast to a treatment with a hydrolyzing enzyme; iii) subjecting the above mixture to a treatment with an acid followed by sedimentation; iv) separating the supernatant and subjecting the sediment to a treatment with an alkali solution followed by sedimentation, v) blending the supernatants of step iv) to obtain said yeast extract.

Another aspect of the present disclosure provides a method of mitigating stress and increasing yield in a plant and/or a plant part comprising applying to the plant, a plant part, or a locus an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients or micronutrients.

Another aspect of the present disclosure provides a use of an agricultural composition for mitigating stress in a plant and/or a plant part, wherein said composition comprises: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients or micronutrients.

Detailed description

For the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of materials/ingredients used in the specification are to be understood as being modified in all instances by the term "about".

Unless otherwise stated, all exact values provided herein are representative of corresponding approximate values (e.g., all exact exemplary values provided with respect to a particular factor or measurement can be considered to also provide a corresponding approximate measurement, modified by "about," where appropriate). As used herein, the term "about" refers to a measurable value such as a parameter, an amount, a temporal duration, and the like and is meant to include variations of +/- 15% or less, specifically variations of +/-10% or less, more specifically variations of +/-5% or less, even more specifically variations of +/-1% or less, and still more specifically variations of +/-0.1% or less of and from the particularly recited value, in so far as such variations are appropriate to perform in the disclosure described herein. Recitation of ranges of values are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All provided ranges of values are intended to include the end points of the ranges, as well as values between the end points, and are independently combinable. As used herein, all numerical values or numerical ranges include integers within such ranges and fractions of the values or the integers within ranges unless the context clearly indicates otherwise. Thus, for example, reference to a range of 90-100%, includes 91%, 92%, 93%, 94%, 95%, 95%, 97%, etc., as well as 91.1%, 91.2%, 91.3%, 91.4%, 91.5%, etc., 92.1%, 92.2%, 92.3%, 92.4%, 92.5%, etc., and so forth. All methods described herein can be performed in a suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

It must be noted that, as used in this specification, the singular forms “a,” “an” and “the” include singular and plural referents unless the content clearly dictates otherwise. The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances.

As used herein, the terms “comprising” “including,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to.

The term “plant” or “target plant” as used herein refers to any vegetation to which the compositions of the present disclosure can be applied for any purposes or any treatment. The term covers a whole plant or a part thereof, such as stems, branches, bark, pistils, flowers, petals, sepals, roots, rhizomes, buds, bulbs, tubers, petioles, nodes, internodes, leaves, leaflets, meristems, root tips, shoot tips, fruits, reproductive organs such as anther, stamen, carpel, ovary, style, stigma, and so forth. The term also covers seeds, seedlings, or any plant propagation material.

The term "plant propagation material" is to be understood to denote all the generative parts of the plant such as seeds and vegetative plant material such as cuttings and tubers (e. g. potatoes), which can be used for the multiplication of the plant. This includes seeds, roots, fruits, tubers, bulbs, rhizomes, shoots, sprouts and other parts of plants. Seedlings and young plants, which are to be transplanted after germination or after emergence from soil, may also be included. These plant propagation materials may be treated prophylactically with a plant protection compound either at or before planting or transplanting. In an embodiment, the term includes agronomically useful plants, for example for example vegetable, fruit and cereal crops, and ornamental plants.

The term “locus” as used herein shall denote the vicinity of the target plant in which growth stimulation is desired. The locus includes the vicinity of the target plant which has either emerged or is yet to emerge. The term “target plant” shall include a multitude of desired crop plants or an individual crop plant growing at a locus. The said locus includes the area, medium and soil where the target plant grows.

The term “biostimulant” as used herein refers to a product, ingredient, or a composition which when applied to a plant and/or a part thereof results in a positive change or any improvement in plant health, phenotypic or genotypic characteristics of a plant; visible beneficial changes in a plant; improvement in plant stress and disease tolerance; and improvement in yield and quality of produce. Non-limiting examples of changes or improvement effected by a biostimulant include: Improved plant nutrient use efficiency; Enhanced root and shoot growth; Improved reproductive heat stress tolerance; Improved drought tolerance; Improved pollen tube growth; Enhanced pollen viability; Increased fertilization and fruit set; Increased floral inflorescence primordia; Increased number of buds, pods and yield; Improved and strong root mass and architecture; Improved/increased bud development; Accelerated shoot or bud emergence; Enhanced vigor/uniformity of emergence; Improved and increased branching; Improved/increased diameter and strength; Improved/increased inter-node length; Increase in number of yield structures (ears, fruits etc); Increase in leaf area; Increased amount of chlorophyll, greening; Increased photosynthesis activity; Increase in CO2 fixation; Accelerated and improved flowering; Improvement in pollination; Enhanced fruit set & retention; Improvement in cell division for size and quality potential; Improvement in fruit finish; Freedom from pest such as fungal pests, viruses, bacteria, weeds, insects, nematodes; Enhanced resistance against pest such as fungal pests, viruses, bacteria, weeds, insects, nematodes; Increased plant weight; Increased plant height; Increased biomass such as higher overall fresh weight; Higher grain yield; More tillers; Larger leaves; Increased shoot growth; Increased protein content; Increased oil content; Increased starch content; Increased pigment content; Increased plant vigor; Improved vitality of the plant; Improved plant growth; Improved plant development; Improved visual appearance of the plant or a part thereof; Improved plant stand (less plant verse/lodging); Improved emergence; Enhanced nodulation, in particular rhizobial nodulation; Bigger leaf blade; Increased yield when grown on poor soils or unfavorable climate; Enhanced pigment content (e.g. Chlorophyll content); Earlier flowering; Earlier fruiting; Earlier and improved germination; Earlier grain maturity; Improved self-defence mechanisms; Improved stress tolerance and resistance of the plants against biotic and abiotic stress factors such as fungi, bacteria, viruses, insects, heat stress, cold stress, drought stress, UV stress and/or salt stress; Less non-productive tillers; Less dead basal leaves; Less input needed (such as fertilizers or water); Greener leaves; Complete maturation under shortened vegetation periods; Less fertilizers needed; Less seeds needed; Easier harvesting; Faster and more uniform ripening; Longer shelf-life; Longer panicles; Delay of senescence; Stronger and/or more productive tillers; Better extractability of ingredients; Improved quality of seeds (for being seeded in the following seasons for seed production); Reduced production of ethylene and/or the inhibition of its reception by the plant; Increased nutrient content; Increased content of fatty acids; Increased metabolite content; Increased carotenoid content; Increased sugar content; Increased amount of essential amino acids Improved nutrient composition; Improved protein composition; Improved composition of fatty acids; Improved metabolite composition; Improved carotenoid composition; Improved sugar composition; Improved amino acids composition; Improved or optimal fruit color; Improved leaf color; Higher storage capacity; and/or Higher processability of the harvested products.

Thus, before describing the present disclosure in detail, it is to be understood that this invention is not limited to particularly exemplified process parameters or composition that may of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the scope of the invention in any manner. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.

An embodiment of the present disclosure provides an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; and c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof.

In an embodiment, said composition further comprises one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof, wherein the additional plant growth promoter is not a yeast-based plant growth promoter.

An embodiment of the present disclosure provides an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof.

In an embodiment, the yeast-based plant growth promoter belongs to (derived from) a yeast selected from the genera Saccharomyces, Kluyveromyces, Hanseniaspora, Metschnikowia, Pichia, Starmerella, Torulaspora, Brettanomyces, Lachancea, Schizosaccharomyces or Candida. Preferably, the yeast-based plant growth promoter belongs to a yeast of the genus Saccharomyces. More preferably, the yeast-based plant growth promoter belongs to the yeast Saccharomyces cerevisiae.

In an embodiment, the yeast-based plant growth promoter is a yeast extract, an inactive yeast, yeast cell walls or yeast cell-wall derivatives. In a preferred embodiment, the yeast-based plant growth promoter is a yeast extract.

In an embodiment, the yeast extract is a cell-free fermentation extract, cell-free spent media, yeast hydrolysate, cell-free yeast hydrolysate, yeast autolysate, cell-free yeast autolysate, fermentation extract comprising live or dead cells, spent media comprising live or dead cells, or an unfiltered extract comprising lysed cells and cell debris. In a preferred embodiment, the yeast extract is a cell-free yeast hydrolysate.

In an embodiment, the yeast-based plant growth promoter is a yeast extract obtained through an alkaline hydrolysis, an enzymatic hydrolysis, an acid hydrolysis, a physical treatment, a mechanical treatment, or combinations thereof. Preferably, the yeast extract is obtained through a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis.

Thus, in a preferred embodiment, the yeast-based plant growth promoter is a yeast extract, wherein the yeast extract is obtained through a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis.

In another preferred embodiment, the yeast-based plant growth promoter is a yeast extract, wherein the yeast extract is a cell-free yeast hydrolysate obtained through a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis.

In an embodiment, the B group vitamin is selected from thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate, cyanocobalamine or derivatives thereof.

In an embodiment, the metabolic co-factor is a B group vitamin selected from thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate, cyanocobalamine or derivatives thereof. In a specific embodiment, the B group vitamin is pyridoxine or derivatives thereof. In a specific embodiment, the B group vitamin is thiamine or derivatives thereof. In a specific embodiment, the B group vitamin is riboflavin or derivatives thereof.

In an embodiment, the metabolic co-factor is ascorbic acid.

In an embodiment, the metabolic co-factor is a combination of one or more B group vitamins and ascorbic acid.

In an embodiment, the chelating agent is humic acid. In an embodiment, the chelating agent is fulvic acid. In an embodiment, the chelating agent is a combination of humic acid and fulvic acid.

In an embodiment, the additional plant growth promoter is one or more amino acids, L-amino acids, or derivatives thereof. Thus, in an embodiment, the composition of the present disclosure further comprises one or more additional amino acid(s), macronutrients, micronutrients, or combinations thereof. In an embodiment, said composition comprises one or more additional amino acid(s). In an embodiment, said composition comprises one or more additional macronutrients. In an embodiment, said composition comprises one or more additional micronutrients. In a preferred embodiment, said composition comprises one or more additional amino acid(s), micronutrients, and macronutrients. In an embodiment, the macronutrients or micronutrients are added to the composition of the present disclosure as inorganic salts. In an embodiment, the macronutrients or micronutrients may be selected from nitrogen or salts thereof, phosphorus or salts thereof, potassium or salts thereof, zinc or salts thereof, magnesium or salts thereof, manganese or salts thereof, boron or salts thereof, calcium or salts thereof, iron or salts thereof, or combinations thereof. In an embodiment, zinc or salts thereof is in form of zinc sulphate heptahydrate. In an embodiment, magnesium or salts thereof is in form of magnesium sulphate. In an embodiment, manganese or salts thereof is in form of manganous chloride. In an embodiment, boron or salts thereof is in form of boric acid. In an embodiment, calcium or salts thereof is in from of calcium chloride. In an embodiment, iron or salts thereof is in form of ferrous sulphate. In a preferred embodiment, the additional macronutrients or micronutrients may be selected from zinc sulphate heptahydrate, magnesium sulphate, manganous chloride, boric acid, calcium chloride, ferrous sulphate, or combinations thereof.

In an embodiment, the macronutrients or micronutrients may be present in the composition in a chelated form.

In an embodiment, said additional plant growth promoter is an amino acid, an L-amino acid, or derivatives thereof. In an embodiment, the amino acid or L-amino acid may be selected from lysine, glycine, aspartic acid, alanine, tryptophan, proline, isoleucine, histidine, leucine, threonine, glutamic acid, tyrosine, serine, glutamine, phenylalanine, cysteine, valine, asparagine, arginine, sarcosine, L-lysine, L-glycine, L-aspartic acid, L-alanine, L-tryptophan, L-proline, L-isoleucine, L-histidine, L-leucine, L-threonine, L-glutamic acid, L-tyrosine, L- serine, L-glutamine, L-phenylalanine, L-cysteine, L-valine, L-asparagine, L-arginine, L- sarcosine, or combinations thereof. In an embodiment, the amino acid or L-amino acid may be derived from a synthetic source or a natural source.

In an embodiment, the yeast-based plant growth promoter is present in the composition in an amount ranging from about 1% w/w to about 90% w/w of the total weight of the composition. In an embodiment, the yeast-based plant growth promoter is present in the composition in an amount ranging from about 10% w/w to about 90% w/w of the total weight of the composition. In an embodiment, the yeast-based plant growth promoter is present in the composition in an amount ranging from about 30% w/w to about 90% w/w of the total weight of the composition. In an embodiment, the yeast-based plant growth promoter is present in the composition in an amount ranging from about 50% w/w to about 90% w/w of the total weight of the composition. In a specific embodiment, the yeast extract is present in the composition in an amount ranging from about 50% w/w to about 80% w/w of the total weight of the composition.

In an embodiment, yeast-based plant growth promoter is characterized by presence of organic carbon in the range of about 5% w/w to about 6% w/w of the total weight of the yeast-based plant growth promoter.

In an embodiment, the metabolic co-factor is present in the composition in an amount ranging from about 0.01% w/w to about 30% w/w of the total weight of the composition.

In an embodiment, the chelating agent is present in the composition in an amount ranging from about 0.1% w/w to about 50% w/w of the total weight of the composition. In an embodiment, the chelating agent is present in the composition in an amount ranging from about 1% w/w to about 50% w/w of the total weight of the composition.

In an embodiment, the one or more additional plant growth promoters, macronutrients or micronutrients are present in the composition in an amount ranging from about 0% w/w to about 50% w/w of the total weight of the composition. In an embodiment, the one or more additional plant growth promoters, macronutrients or micronutrients are present in the composition in an amount ranging from about 0.01% w/w to about 50% w/w of the total weight of the composition.

In an embodiment, the one or more macronutrients or micronutrients are present in the composition in an amount ranging from about 0% w/w to about 30% w/w of the total weight of the composition. In an embodiment, the one or more macronutrients or micronutrients are present in the composition in an amount ranging from about 0.01% w/w to about 30% w/w of the total weight of the composition.

In an embodiment, the composition may further comprise one or more externally added amino acids as additional plant growth promoter. The amino acids may be added externally in an amount ranging from about 0% w/w to about 20% w/w of the total weight of the composition. The amino acids may be added externally in an amount ranging from about 0.1% w/w to about 20% w/w of the total weight of the composition.

In any of the composition, methods, or uses of the invention of the present disclosure, the composition may further comprise an agriculturally acceptable carrier.

Thus, an embodiment of the present disclosure provides an agricultural composition comprising: a. a yeast-based plant growth promoter obtainable by a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof.

In a preferred embodiment, the yeast-based plant growth promoter is a yeast extract. In another preferred embodiment, the yeast-based plant growth promoter is a yeast extract, wherein the yeast extract is a cell-free yeast hydrolysate.

An embodiment of the present disclosure provides an agricultural composition comprising: a. 1% w/w to about 90% w/w of a yeast-based plant growth promoter; b. 0.01% w/w to about 30% w/w of a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. 0.1% w/w to about 50% w/w of a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, 0% w/w to about 50% w/w of one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof.

An embodiment of the present disclosure provides an agricultural composition comprising: a. 1% w/w to about 90% w/w of a yeast-based plant growth promoter obtainable by a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis; b. 0.01% w/w to about 30% w/w of a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. 0.1% w/w to about 50% w/w of a chelating agent selected from humic acid, fill vic acid, or combinations thereof; and d. optionally, 0% w/w to about 50% w/w of one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof.

The embodiments of the present disclosure also provide a process of preparing the yeast-based plant growth promoter, in particularly a yeast extract.

In an embodiment, there is provided a process of preparing a yeast extract comprising the following steps: i) providing an inoculum of yeast; ii) subjecting the yeast to a treatment with a hydrolyzing enzyme; iii) subjecting the above mixture to a treatment with an acid followed by sedimentation; iv) separating the supernatant and subjecting the sediment to a treatment with an alkali solution followed by sedimentation, v) blending the supernatants of step iv) to obtain said yeast extract.

In an embodiment, the yeast extract obtained by the process mentioned herein the embodiment of the present disclosure is a cell-free yeast hydrolysate.

In an embodiment, the hydrolyzing enzyme used can be selected from papain or proteolytic enzymes such as pepsin, alcalase, and/or trypsin. In a preferred embodiment, the hydrolyzing enzyme used is papain.

In an embodiment, the acid used in the process is an acid selected from lactic acid, citric acid, sulphuric acid, and hydrochloric acid. In a preferred embodiment, the acid is hydrochloric acid.

In an embodiment, the concentration of the acid ranges from 20% to 100 %, preferably 25% to 99%. In an embodiment, the concentration of the acid may be in the range of 28% to 36%. In an embodiment, the concentration of the acid may be in the range of 78% to 98%.

In an embodiment, the alkali may be selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, ammonia, or combinations thereof. In an embodiment, the preferred alkali is potassium hydroxide. In an embodiment, the pH of the solution after the acid hydrolysis step is in a range of about 2.5 to 3.5. The pH of the solution after the alkaline hydrolysis is in a range of about 5.5 to 6.5. The pH of the final composition is in a range of about 2.0 to 7.0, preferably 2.5 to 6.5, even more preferably 3.0 to 5.0. In a preferred embodiment, the pH of the composition of the present disclosure is in a range of about 3.0 to 4.0

The present disclosure further provides a yeast extract obtained by a process comprising the following steps: i) providing an inoculum of yeast; ii) subjecting the yeast to a treatment with a hydrolyzing enzyme; iii) subjecting the above mixture to a treatment with an acid followed by sedimentation; iv) separating the supernatant and subjecting the sediment to a treatment with an alkali solution followed by sedimentation, v) blending the supernatants of step iv) to obtain said yeast extract.

An embodiment also provides a process of making the composition of the present disclosure. In an embodiment, the composition of the present disclosure is obtained by a process comprising the following steps: i) providing a yeast-based plant growth promoter; ii) optionally, adding one or more plant growth promoters, micronutrients and/or macronutrients to said yeast extract and allowing the solution to settle; iii) blending a chelating agent with the supernatant obtained from step ii); iv) adding a metabolic co-factor selected from B group of vitamins, ascorbic acid or combinations thereof to the mixture obtained in step iii) to obtain the final composition.

In an embodiment, the yeast-based plant growth promoter is a yeast extract obtained through an alkaline hydrolysis, an enzymatic hydrolysis, an acid hydrolysis.

In an embodiment, said composition of the present disclosure is a biostimulant or a biofertilizer composition.

In an embodiment, said composition of the present disclosure is a biostimulant composition. In an embodiment, said composition of the present disclosure is a biofertilizer composition.

In an embodiment, said composition of the present disclosure is a stress-mitigating agent for the plant and/or a plant part it is applied to.

In an embodiment, the present disclosure provides a composition for: reducing the effects of abiotic stress in a plant and/or a plant part; increasing the tolerance to abiotic stress of a plant and/or a plant part; and/or increasing biomass or yield of a plant and/or a plant part under abiotic stress; wherein said method comprises contacting the plant and/or the plant part or soil with the composition of the present disclosure. Contacting the plant and/or the plant part or the soil with the composition of the present disclosure may thereby reduce the effects of abiotic stress in the plant and/or the plant part and/or increase the tolerance to abiotic stress of the plant and/or the plant part and/or increase biomass or yield of the plant and/or the plant part compared to an untreated plant and/or plant part.

In an embodiment, said composition is applied at about 50 ml/ha to about 500 ml/ha. In an embodiment, said composition is applied at about 60 ml/ha to about 400 ml/ha. In an embodiment, said composition is applied at about 70 ml/ha to about 300 ml/ha. In an embodiment, said composition is applied at about 80 ml/ha to about 200 ml/ha. In an embodiment, said composition is applied at about 90 ml/ha to about 100 ml/ha. In a preferred embodiment, said composition is applied at about 90 ml/ha to about 100 ml/ha.

In an embodiment, the present disclosure provides a method for: reducing the effects of abiotic stress in a plant and/or a plant part; increasing the tolerance to abiotic stress of a plant and/or a plant part; and/or increasing biomass or yield of a plant and/or a plant part under abiotic stress; wherein said method comprises contacting the plant and/or the plant part or soil with the composition of the present disclosure. Contacting the plant and/or the plant part or the soil with the composition of the present disclosure may thereby reduce the effects of abiotic stress in the plant and/or the plant part and/or increase the tolerance to abiotic stress of the plant and/or the plant part and/or increase biomass or yield of the plant and/or the plant part compared to an untreated plant and/or plant part.

Another embodiment of the present disclosure provides a method of mitigating stress and increasing growth and yield in a plant and/or a plant part comprising applying to a plant and/or a plant part or a locus an agricultural composition comprising: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients or micronutrients.

Another embodiment of the present disclosure provides a use of an agricultural composition for mitigating stress in a plant and/or a plant part, wherein said composition comprises: a. a yeast-based plant growth promoter; b. a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; c. a chelating agent selected from humic acid, fulvic acid, or combinations thereof; and d. optionally, one or more additional plant growth promoters, macronutrients or micronutrients.

In an embodiment, said abiotic stress may be high temperature, heat, drought, water stress, high light intensity, hail, cold temperature, freezing, chilling, salinity, ozone, or combinations thereof.

In any of the methods or uses of the present disclosure, said method or use may further comprise separately, simultaneously or sequentially contacting the plant and/or the plant part with one or more additional agricultural compound. In any of the methods or uses of the present disclosure, said method or use may further comprise simultaneously contacting the plant and/or the plant part with one or more additional agricultural compound.

The plants on which the compositions of the present disclosure can be used are agronomically useful plants and/or a plant part, for example for example vegetable, fruit and cereal crops, and ornamental plants. The agronomically useful plants and/or a plant part are angiosperms selected from the group consisting of Apiaceae, Asteraceae, Brassicaceae, Chenopodiaceae, Convolvulaceae, Cucurbitaceae, Fabaceae, Gramineae, Liliaceae, Polygonaceae, Rosaceae, Solanaceae, Poaceae, the Vitaceae. Thus, in an embodiment, the target plant and/or a plant part is selected from crops, cereals, fruits, vegetables, nuts, vines, nursery plants and flowers. In an embodiment, non-limiting examples of target plant and/or a plant part include com, cereals such as rice, wheat, barley, rye, oat, sorghum, millet, triticale, buckwheat, etc.; cotton, soybean, beet, row crops, legumes, grams, sugar cane, tobacco, etc.; oilseeds such as oilseed rape, peanut/groundnut, rape seed, sunflower, etc.; vegetables: solanaceous vegetables such as eggplant, tomato, pimento, pepper, potato, etc., cucurbit vegetables such as cucumber, pumpkin, zucchini, water melon, melon, squash, gourds, muskmelon, etc., cruciferous vegetables such as radish, white turnip, horseradish, kohlrabi, cabbage, leaf mustard, broccoli, cauliflower, brussels sprouts, kale, etc., asteraceous vegetables such as burdock, crown daisy, artichoke, lettuce, etc, liliaceous vegetables such as green onion, onion, shallot, garlic, and asparagus, ammiaceous vegetables such as carrot, parsley, celery, parsnip, leek, etc., chenopodiaceous vegetables such as spinach, swiss chard, etc., lamiaceous vegetables such as Perilla frutescens, mint, basil, etc.; herbs and spices such as coriander, chamomile, cassia, catnip, clove, cumin, curry, cilantro, cinnamon, cardamom, dill, anise, juniper, lavender, parsley, rosemary, marigold, mustard, nutmeg, fennel, poppy, thyme, vanilla, saffron, poppy, sage, wintergreen, etc.; flowers, foliage plants, turf grasses, fruits: pome fruits such apple, pear, quince, guava, etc, stone fleshy fruits such as peach, plum, nectarine, cherry, apricot, prune, etc., citrus fruits such as orange, lemon, lime, grapefruit, mandarin, malta, kumquat, pummelo, tangerine, tangor, uniq, etc., nuts such as chestnuts, walnuts, hazelnuts, almond, pistachio, cashew nuts, macadamia nuts, pecan nut, cashew nut, hazel nut, pine nut, etc. berries such as caneberry, strawberry, blueberry, cranberry, blackberry, raspberry, coryberry, darrowberry, dewberry, thornless berry, evergreen blackberry, himalayaberry, hullberry, lavacaberry, loganberry, lowberry, lucretiaberry, mammoth blackberry, marionberry, mora, mures deronce, nectarberry, olallieberry, evergreen berry, phenomenalberry, rangeberry, ravenberry, rossberry, dewberry, tayberry, youngberry, zarzamora, aronia berry, currant, elderberry, barberry, gooseberry, honeysuckle, huckleberry, jostaberry, juneberry, lingonberry, salal, seabuckthorn, bayberry, buffaloberry, chokecherry, maypop, mulberry, bearberry, bilberry, cloudberry, muntries, partridgeberry, etc., grape, kaki fruit, kiwi fruit, olive, plum, banana, coffee, date palm, coconuts, papaya, persimmon, avocado, dragon fruit, pomegranate, lychee, jackfruit, pineapple, passionfruit, sapota, etc., trees other than fruit trees; tea, mulberry, flowering plant, trees such as ash, birch, dogwood, eucalyptus, Ginkgo biloba, lilac, maple, Quercus, poplar, Judas tree, Liquidambar formosana, plane tree, zelkova, Japanese arborvitae, fir wood, hemlock, juniper, Pinus, Piceci, and Taxus cuspidate, etc., other crops such as chive, day lily, Elegans hosta, Fritillaria, gojiberry, okra, pea, hops, beans, guar, radish, amaranth, jute, fenugreek, lentils, chickpea, artichoke, rhubarb, licorice, sweet potato, Dioscorea japonica, colocasia, ornamental grasses (lawn turf, sod, etc.), varieties and cultivars thereof. The compositions of the present disclosure as per an embodiment can be applied

• Pre-emergence

• Post-emergence

• Before sowing

• Pre-harvest

• Post-harvest

In an embodiment, the compositions of the present disclosure are applied before planting/sowing; at the time of sowing, germination, early leaf stage, early bloom stage, prebloom stage, full bloom stage, petal fall stage, swollen bud stage, bud break stage, post petal fall stage, post bud break stage, pre-bud break stage, full pistillate stage, post pollination stage, square formation stage, pegging stage, post-pegging stage, fruit set stage, early mid-bloom, greenup (post-dormancy) stage, bud set stage, etc; after flowering stage; harvest stage; and/or post-harvest. In an embodiment, the compositions of the present disclosure may be applied anytime throughout the growth stage as conventionally known to a person skilled in the art. The time of application depends on the target plant; environmental conditions such as nutrient deficiency, biotic and abiotic stresses; type of application and the expected outcome or any other parameter known to a person skilled in the art. Applications can be made throughout the growth of the plant, one or more times a week.

In an embodiment, the compositions of the present disclosure are applied directly and/or indirectly to the plant and/or to plant propagation material by drenching the soil, by drip application onto the soil, by soil injection, by dipping or by treatment of seeds.

The compositions of the present disclosure may be applied by dusting, spraying, granular application, seed pelleting/seed dressing, broadcasting, in furrow application, side dressing, spot application, ring application, root zone application, pralinage, seedling root dip, sett treatment, trunk/stem injection, padding, swabbing, root feeding, soil drenching, capsular placement, baiting, fumigation, banding, foliar application, basal application, space treatment, enclosed space fumigation and such other methods which may help prevent or control or eradicate the disease.

In a preferred embodiment, the compositions of the present disclosure are applied as a drench application, in-furrow application, soil, drip irrigation, soil injection, hydroponic application, capillary action application, root infiltration, or a foliar application. In an embodiment, the compositions of the present disclosure is applied as a seed treatment such as seed soak application, seed coating application, germination treatment; or a rooting/shooting dip treatment. The type of application is decided as per the target plant, the outcome expected, and the time of application and any other conventional parameters as known to a person skilled in the art.

The compositions of the present disclosure can be applied by the use of conventional ground sprayers, granule applicators, watering (drenching), drip irrigation, spraying, atomizing, broadcasting, dusting, foaming, spreading-on, aerial methods of spraying, aerial methods of application, methods utilizing application using modem technologies such as, but not limited to, drones, robots, predosage device, a knapsack sprayer, a spray tank, a spray plane, or an irrigation system and by other conventional means known to those skilled in the art.

In a further embodiment, the compositions of the present disclosure are combined with, formulated with and/or applied with one or more additional agrochemically active substances. According to an embodiment, the said agrochemically active substance is selected from fertilizers, mycorrhiza, micronutrients, acaricides, algicides, antifeedants, avicides, bactericides, bird repellents, chemosterilants, fungicides, herbicide safeners, herbicides, insect attractants, insect repellents, insecticides, mammal repellents, mating disrbyrs, molluscicides, nematicides, plant activators, plant-growth regulators, rodenticides, synergists, virucides, derivatives thereof, biological control agents, superabsorbent polymers and mixtures thereof.

All headings and sub-headings are used herein for convenience only and should not be constmed as limiting the invention in any way.

The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be constmed as indicating any non-claimed element as essential to the practice of the invention.

Examples

Example 1: Production of yeast-based plant growth promoter, i.e. cell-free yeast hydrolysate

A pure culture of Saccharomyces cerevisiae (MTCC accession no.: 25522) maintained by lyophilization was used and working cultures were prepared from concentrated lyophilized culture. Primary Seed inoculum of Saccharomyces cerevisiae was prepared using Malt extract, Peptone, and Glucose in a flask. Contamination and growth were checked before inoculating to prepare Secondary seed inoculum.

For fermentation specific growth media was prepared with Glucose, Malt extract, and Peptone, pH of the media was maintained at 6.5-7.0. The media was sterilized for 20 min. Prior to inoculation the media was cooled to room temperature and inoculated using Secondary seed inoculum of about 0.1% to 40% to the media volume through sterilized conditions into the flask/fermenter. The media temperature was maintained at room temperature for the growth phase. After 3 days of fermentation, the temperature of the broth was increased to 40-85°C and added with a hydrolase enzyme and agitated for 1-6 hours. After enzyme hydrolysis, the temperature was raised to 60-120°C to deactivate the enzyme and at the same temperature hydrochloric acid was added and agitated for 3-10 hours. Extracted broth was cooled down to room temperature and keep for settlement. Supernatant was transferred to another vessel and 5% Caustic potash solution was added to the sediment and the temperature was increased to 60-120°C, agitated for 3-10 hours. Extracted broth was cooled down to room temperature and keep for settlement. The supernatant of this step was blended with the supernatant of enzyme and acid hydrolysis followed by filtration with 0.1 - 3 mm filters to obtain clear cell-free yeast hydrolysate.

Example 2: Production of biofertilizer/biostimulant composition

The cell-free yeast hydrolysate thus obtained in Example 1 was used to prepare the composition of the present disclosure.

About 67% of cell-free yeast hydrolysate was fortified with inorganic salts such as Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure.

Table 1 : Composition of yeast extract

Example 3: Production of biofertilizer/biostimulant composition enriched with amino acids

The cell-free yeast hydrolysate thus obtained in Example 1 was used to prepare the composition of the present disclosure .

About 59% cell-free yeast hydrolysate was fortified with inorganic salts - Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The mixture was enriched with 80% amino acid solution comprising all 20 amino acids to obtain a final composition comprising total amino acid content in the range of about 12-15% w/w of the total weight of the composition. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure. Table 2: Composition of yeast extract with amino acid powder

Example 4: Production of biofertilizer/biostimulant composition

The cell-free yeast hydrolysate thus obtained in Example 1 was used to prepare the composition of the present disclosure. About 75% cell-free yeast hydrolysate was fortified with inorganic salts - Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The mixture was enriched with 80% amino acid solution comprising all 20 amino acids to obtain a final composition comprising total amino acid content in the range of about 12-15% w/w of the total weight of the composition. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure.

Table 3 : Composition of yeast extract with amino acids

Example 5: Production of biofertilizer/biostimulant composition

About 75% cell-free yeast hydrolysate was fortified with inorganic salts - Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The mixture was enriched with 80% amino acid solution comprising all 20 amino acids to obtain a final composition comprising total amino acid content in the range of about 12-15% w/w of the total weight of the composition. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure.

Table 4: Composition of yeast extract with amino acids

Example 6: Production of biofertilizer/biostimulant composition

About 75% cell-free yeast hydrolysate was fortified with inorganic salts - Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride,

Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure. Table 5 : Composition of yeast extract

Example 7: Production of biofertilizer/biostimulant composition

About 75% cell-free yeast hydrolysate was fortified with inorganic salts - Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate. The blended mixture was allowed to settle, and supernatant was separated and blended with Fulvic acid 4% SL. The mixture was filtered. The filtrate was enriched with Vitamin B6, and Ascorbic acid. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure. Table 6: Composition of yeast extract

Example 8: Production of biofertilizer/biostimulant composition

The cell-free yeast hydrolysate thus obtained in Example 1 was used to prepare the composition of the present disclosure. About 75% cell -free yeast hydrolysate was fortified with other ingredients such as inorganic salts (Zinc sulphate heptahydrate, Magnesium sulphate, Manganous chloride, Boric acid, Calcium chloride, Ferrous sulphate), Fulvic acid Vitamin B6, and Ascorbic acid. The cell-free yeast hydrolysate was characterized by total amino acid content in the range of about 12% w/w - 15% w/w and total organic carbon in the range of 5% w/w - 6% w/w of the total weight of the yeast extract. The final mixture was filtered to remove any undissolved material to obtain the composition of the present disclosure.

Table 7 : Composition of yeast extract

Example 9: Efficacy of composition of Example 4 on soybean The composition of example 4 was applied on soybean and its effect on growth and development of soybean was evaluated. A plot of 5m x 5m was planted with soybean with a spacing of 45cm x 5 cm. The experimental design contained 3 replicates of every treatment. 3 treatments of composition of example 4 were conducted at rates of 50 ml/ha, 75 ml/ha and 100 ml/ha. Each treatment included 2 applications of the composition, first application A at 10 days after sowing (DAS) and second application B at 25 DAS. For efficacy, following parameters were evaluated and compared with an untreated set of soybean plants: a. Phytotoxicity (0-10 scale) : where 0=No phytotoxicity and 10=100% crop damage (10DAA,10DAB) b. Plant vigour (0-10 scale) : where 0=poor and 10=excellent (10DAA,10DAB) c . Plant height at 10 DAB & at harvest (10 randomly selected, tagged plants per treatment) d. No of flower/Pods/ plant at (10DAB & at harvest) e . Seed yield kg per plot at harvest f. Yield Q/ha Table 8: Biostimulant effect of composition of example 4 on soybean plant growth and development

Table 9: Biostimulant effect of composition of example 4 on soybean yield

From the above table, it can be observed that the composition of example 4 at 100 ml/ha showed excellent crop vigour, followed by more no. of pod/ plant and yield. The composition of example 4 at 100 ml/ha showed excellent incremental yield (5.7 %) compared to the untreated control. Example 10: Efficacy of composition of Example 7 on soybean

The composition of example 7 was applied on soybean and its effect on growth and development of soybean was evaluated. A plot of 5m x 2.5m was planted with soybean with a spacing of 60cm row to row. The experimental design contained 4 replicates of every treatment. 3 treatments of composition of example 7 were conducted at rates of 50 ml/ha, 125 ml/ha and 150 ml/ha. Each treatment included 2 applications of the composition, first application at 17 days after sowing (DAS) and second application at 36 DAS. For efficacy, following parameters were evaluated and compared with an untreated set of soybean plants at 90DAS stage: number of branches and number of pods per plant.

Table 10: Biostimulant effect of composition of example 7 on soybean plant growth and yield

Example 11: Efficacy of yeast extract obtained by different processes.

Six types of yeast extract were prepared as per table 11 -

Table 11 : Yeast extracts prepared by different methods

Pot trials of soybean were set up with 3 replicates for every treatment. The yeast extracts (Extracts 1-6) were applied as foliar spray 10 days after transplanting the plants in pots (3-4 leaf stage), with a water spray volume of 500 L/ha, and at a rate of 0.5 ml/L. A second application of the extracts was done 15 days after the first application. The plants were evaluated for their leaf size (in terms of leaf area sq. cm) 15 days after second spray. The results are presented below:

Table 12: Effect of yeast extracts of table 11 on soybean leaf growth

From the above table, it is observed that an extract produced by the combination of enzyme hydrolysis, acid hydrolysis and alkaline hydrolysis (Extract 5) produces wider and bigger leaves than other extracts with 1314% increase in leaf size.

Example 12: Efficacy of yeast extract obtained by different processes.

Following treatment composition were prepared as shown in table 13:

Table 13: Treatment compositions

Pot trials of soybean were set up with 3 replicates for every treatment. The treatments (Treatment 1-7) were applied as foliar spray 10 days after transplanting the plants in pots (3-4 leaf stage), with a water spray volume of 500 L/ha, and at a rate of 0.5 ml/L. A second application of the extracts was done 15 days after the first application. The plants were evaluated for their leaf size (in terms of leaf area sq. cm) 15 days after second spray. The results are presented below:

Table 14: Effect of treatment compositions of table 13 on soybean leaf growth

From the above table, it is observed that Treatment 6 show the highest efficacy with more than 1000% increase in leaf area.

Claims

We Claim:

1. An agricultural composition comprising:

(a) a yeast-based plant growth promoter;

(b) a metabolic cofactor selected from B group of vitamins, ascorbic acid, or combinations thereof; and

(c) a chelating agent selected from humic acid, fulvic acid, or combinations thereof.

2. The agricultural composition of claim 1, wherein the composition further comprises optionally one or more additional plant growth promoters, macronutrients, micronutrients, or combinations thereof.

3. The agricultural composition of claim 1, wherein the yeast-based plant growth promoter belongs to a yeast selected from the genera Saccharomyces, Kluyveromyces, Hansenicisporci, Metschnikowia, Pichia, Starmerella, Torulasporci, Brettanomyces, Lachcinceci, Schizosaccharomyces or Candida.

4. The agricultural composition of claim 3, wherein the yeast-based plant growth promoter belongs to the yeast Saccharomyces cerevisiae.

5. The agricultural composition of claim 1, wherein the yeast-based plant growth promoter is a yeast extract, an inactive yeast, yeast cell walls or yeast cell-wall derivatives.

6. The agricultural composition of claim 5, wherein the yeast-based plant growth promoter is a yeast extract selected from a cell-free fermentation extract, cell-free spent media, yeast hydrolysate, cell-free yeast hydrolysate, yeast autolysate, cell-free yeast autolysate, fermentation extract comprising live or dead cells, spent media comprising live or dead cells, or an unfiltered extract comprising lysed cells and cell debris.

7. The agricultural composition of claim 5, wherein the yeast-based plant growth promoter is a yeast extract obtained through a combination of processes comprising an enzymatic hydrolysis, an acid hydrolysis, and an alkaline hydrolysis.

8. The agricultural composition of claim 1, wherein the B group vitamin is selected from thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate, cyanocobalamine or derivatives thereof.

9. The agricultural composition of claim 2, wherein the additional plant growth promoter is one or more amino acids, L-amino acids, or derivatives thereof.

10. The agricultural composition of claim 2, wherein the macronutrients or micronutrients are added to said composition as inorganic salts selected from nitrogen or salts thereof, phosphorus or salts thereof, potassium or salts thereof, zinc or salts thereof, magnesium or salts thereof, manganese or salts thereof, boron or salts thereof, calcium or salts thereof, iron or salts thereof, or combinations thereof.

11. The agricultural composition of claim 1, wherein the yeast-based plant growth promoter is present in the composition in an amount ranging from about 1% w/w to about 90% w/w of the total weight of the composition.

12. The agricultural composition of claim 1, wherein the metabolic co-factor is present in the composition in an amount ranging from about 0.01% w/w to about 30% w/w of the total weight of the composition.

13. The agricultural composition of claim 1, wherein the chelating agent is present in the composition in an amount ranging from about 0.1% w/w to about 50% w/w of the total weight of the composition.

14. The agricultural composition of claim 2, wherein the optional one or more additional plant growth promoters, macronutrients or micronutrients are present in the composition in an amount ranging from about 0% w/w to about 50% w/w of the total weight of the composition.

15. The agricultural composition of claim 1, wherein the yeast-based plant growth promoter is a yeast extract prepared by a process comprising the following steps:

(i) providing an inoculum of yeast;

(ii) subjecting the yeast to a treatment with a hydrolyzing enzyme;

(iii) subjecting the above mixture to a treatment with an acid followed by sedimentation;

(iv) separating the supernatant and subjecting the sediment to a treatment with an alkali solution followed by sedimentation,

(v) blending the supernatants of step iv) to obtain said yeast extract.

16. A process of preparing the composition of claim 1 comprising the following steps:

(i) providing a yeast-based plant growth promoter;

(ii) optionally, adding one or more plant growth promoters, micronutrients and/or macronutrients to said yeast extract and allowing the solution to settle; (iii) blending a chelating agent with the supernatant obtained from step ii);

(iv) adding a metabolic co-factor selected from B group of vitamins, ascorbic acid or combinations thereof to the mixture obtained in step iii) to obtain the final composition.

17. A method of mitigating stress and increasing growth and yield in a plant and/or a plant part comprising applying to a plant and/or a plant part or a locus an agricultural composition of claim 1.