RU2286048C2 - Method for evaluating nitrogen fixing activity of leguminous crops - Google Patents

Abstract

FIELD: agriculture, in particular, plant growing, more particular, forecasting of accumulation of biological nitrogen in soil by various leguminous crops.

SUBSTANCE: method involves photocolorimetric determining of leghemoglobin pigment content in leguminous plant tubers; defining three extents of nitrogen fixing activity: high, average, and low.

EFFECT: increased efficiency in evaluating nitrogen fixing activity of leguminous crops, annual and perennial grasses.

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Description

The invention relates to the field of agriculture (crop production) and can be used to predict the accumulation of legumes of biological nitrogen in the soil.

Leguminous plants have the ability to fix atmospheric nitrogen, thereby saturating the soil with elements of nitrogen nutrition available to plants and increasing its fertility [1, 2].

A known method for predicting the nitrogen-fixing activity of legumes, involving a visual analysis of the state of nitrogen-fixing nodules located on the root system of plants, while the presence of large pink or red nodules indicates a high nitrogen-fixing activity. If the nodules are small and have a green or brown color, which indicates the absence of nitrogen-fixing pigment, hemhemoglobin (legoglobin), which gives them a color, then nitrogen fixation in plants is low or absent [2]. However, the named method, based on visual signs that carry elements of subjectivity, is not objective.

Using the information that nitrogen-fixing pigment - hemoglobin is a catalyst for the assimilation of atmospheric nitrogen, and nitrogen fixation activity depends on its content in nodules [3], we have developed a new, more objective method of evaluating the nitrogen-fixing activity of legumes based on the above on measuring the concentration of pigment in nodules in 30-day leguminous plants.

For this, at four points of the experimental field, 10 legume plants are dug up. The root system is cleaned of soil and washed in running cold (10-15 ° C) water. Then, using a blade, nodules located in the central part of the root are separated from the root system.

A portion (0.5 g) is homogenized using a homogenizer or ground in a mortar with silica sand in 20 ml of 96% ethanol. In this case, the pigment passes into the alcohol solution.

Then the homogenate is filtered through a thick paper filter, and the filtrate, having a pink color due to the presence of leghemoglobin in it, is used to assess the staining density. The density measurement is carried out using a photoelectric colorimeter (FEC) on a blue light filter at 520 nm. Ethanol is used as a control.

The content of leghemoglobin and the activity of nitrogen fixation is judged by the readings of the device (extinction). At the same time, three degrees of fixation activity are distinguished: high (extinction 0.750 and higher); medium (0.501-0.749) and low (0.500 and below).

The objectivity of the assessment of nitrogen-fixing activity when using the new method is confirmed by the level of accumulation of biological nitrogen accumulated in the soil by various legumes during the growing season.

The results of testing the new method are shown in the table.

Bean culture Indications of the device (extinction), units Degree of activity Nitrogen fixation, kg / ha clover 0.910 high 150 fodder beans 0.780 high 130 alfalfa 0.590 average one hundred peas 0.640 average 110 beans 0.450 low 70 lentils 0.370 low 60

The new method can be used for a comparative assessment of the nitrogen-fixing activity of grain crops, annual and perennial legumes.

Information sources

1. Legumes. Ed. D. Shpaara. - Minsk .: FU Ainform, 2000, - p. 53-56.

2. Crop production / G.S. Posypanov, V.E. Dolgodvorov, G.V. Korenev and others. - M .: Kolos, 1997, - p. 28

3. Crop production of the Central Black Earth region / Ed. V.A. Fedotova, V.V. Kolomeychenko. - Voronezh: Center for the spiritual revival of the Black Earth region. 1996, p. 163, 340.

Claims (1)

A method for evaluating the nitrogen-fixing activity of legumes, including digging up 40 plants, cleaning the root system from the soil, characterized in that the roots are torn with running water at a temperature of 10-15 ° C, then nodules are removed with a blade, the 0.5-gram sample of which is homogenized or triturated in a mortar with quartz sand in 20 ml of 96% ethanol, the homogenate is filtered through a dense paper filter, using a photoelectric colorimeter, the staining density is measured on a blue filter at 520 nm, on the basis of which three steppes are isolated and nitrogen fixation activity: high - extinction 0.750 and higher average - 0,501-0,749 and low - 0,500 and below.