Formation and functioning of the photosynthetic system of corn plants under the influence of elements of growing technology in the Forest-Steppe

Abstract

Relevance. The problem of optimizing the photosynthetic activity of corn crops must be paid attention to the development or improvement of technologies for growing crops, because it is the scientific basis for the application of a technological element. Therefore, the optimization of elements of growing technology as controlled anthropogenic environmental factors in order to organize the optimal morphological structure of the agrocenosis to increase the efficiency of photosynthetic activities is an important way to improve corn grain production systems.

The aim of the study was to establish the influence of certain elements of growing technology - mineral fertilizers, by-products of the predecessor as fertilizers, herbicides, plant growth stimulants, microfertilizers, as well as their integrated application on the formation and functioning of the photosynthetic system of maize plants in the Forest-Steppe.

Materials and methods of research. The research was carried out during 2016-2019 on dark gray wooded coarse-grained light loam soil of the Forest-Steppe with the use of field, calculation-weight and mathematical-statistical methods.

Research results and their discussion. On average, in 2016-2019, under the influence of technologies of different levels of intensity, corn agrocenosis with different biometric parameters were formed, the value of which was determined by the reaction of the crop to changes in growing conditions.

The leaf surface area of corn varied in a wide range depending on the fertilizer and the method of crop care, as well as the stages of plant development. The high variability of the leaf area according to the fertilizer variants testifies to the significance of the influence of this factor in the formation of the assimilation surface of crops and is confirmed by the results of statistical analysis (V = 24.6-31.0 %). Agrocenosis with the largest leaf surface area (49.98-60.31 thousand m²/ha at the stage of BBCH 65) were formed by applying the calculated dose of mineral fertilizers N₂₄₀P₁₂₀K₂₄₀ on the background of by-products of the predecessor, and the smallest – on the natural background of fertility without fertilizers and for the use of winter wheat straw as fertilizer. Among the methods of caring for corn crops by their influence on the assimilation surface area of the agrocenosis, the best was complex II, which on average for all fertilizer variants contributed to the formation of 11.3-15.0 % larger leaf area during BBCH 19-75. During the growing season, the accumulation of dry matter by maize crops took place in an upward trend and was accumulated the most by agrocenosis at the stage of development of BBCH 75 – from 7.10 to 26.43 t/ha. The variability of dry matter mass depending on the fertilizer by methods of care for crops and stages of development was high, which is confirmed by the values of the coefficient of variation V = 28.8-40.5 %. Maize crops on average during the interstage period BBCH 09-75 synthesized 8.54-12.03 g/m² of dry matter per day at an average level of variation of this indicator depending on the fertilizer (V = 10.5-10.6 %), and for of the complex II method of crop care, the net productivity of photosynthesis was on average 6.7 % higher.

The photosynthetic potential of the crop varied significantly more with a high level of variation, which is confirmed by the results of statistical analysis (V = 26.8-28.4 %). Depending on the fertilizer and the method of crop care, this figure increased from 1208.55 in the control version and the application of soil herbicide to 3196.59 thousand m²×day/ha – at the estimated dose N₂₄₀P₁₂₀K₂₄₀ on the background of by-products of the predecessor and integrated application of soil and insurance herbicides , plant growth stimulants and microfertilizers.

Correlation analysis revealed close direct relationships between yield and seed assimilation surface area (r = 0.964-0.999), net photosynthesis productivity (r = 0.967-0.970), and photosynthetic crop potential (r = 0.996).

Maize yield on average for 2016-2019 depended on the factors of intensification of cultivation technology and varied from 3.63 to 12.10 t/ha of grain according to fertilizer options and crop care methods. Under the complex II method, the increase in yield compared to the chemical method averaged 16.7 %. Maize as a high-intensity crop showed a high positive reaction to the increase of agrochemical background in the technology of growing.

Conclusions and prospects. It is established that the elements of growing technology, in particular, different doses of mineral fertilizers and by-products of the predecessor, herbicides, plant growth stimulants, microfertilizers have a positive effect on the formation and functioning of corn agrocenosis, increasing the leaf area, dry matter accumulation, which is manifested in the growth of net productivity of photosynthesis, photosynthetic potential of crops and crop yields.

Maize agrocenosis can be identified as consistently highly productive by achieving the following structural and functional characteristics: leaf surface area at stages BBCH 65 and 75 – 49,98-60,31 and 41,81-47,83 thousand m²/ha, net productivity of photosynthesis – 11,28-12,03 m²/ha per day, photosynthetic sowing potential 2718,89-3196,59 thousand m²×days/ha. Such crops accumulate 21.91-26.43 t/ha of dry matter at the stage of BBCH 75, which is realized in the formation of yield at the level of 10.18-12.10 t/ha of grain.

The research results are used to optimize the technology of growing corn in the Forest-Steppe in order to increase the efficiency of production and agro-climatic resources.