The effect of nutritional backgrounds on the formation of leaf surface and yield and green mass of corn

The leading branch of agriculture in Tatarstan is animal husbandry. In animal husbandry, the main direction is the production of milk and cattle meat. In the diet of dairy cows, corn is an integral component. The share of fodder corn in the total cultivated areas is on average 30–35 %. A limiting factor in the cultivation of corn is the lack of macronutrients in the soil. To obtain stable high yields of green mass of corn, it is necessary to choose the right combination of NPK, based on soil indicators. In this regard, it is necessary to improve the mineral nutrition systems of highly productive adaptive maize hybrids. The effect of fertilizers on leaf surface growth and photosynthetic potential in maize crops was studied in the field on gray forest soils of the Volga region of the Republic of Tatarstan. A significant increase in the yield of green mass was found due to the increased level of mineral nutrition of plants. The fertilizer provided an increase in leaf area by 2.6–9.82 thousand m/ha on the option N60P54K168 and 4.85–14.56 thousand m/ha in N180P154K294. The maximum value of this indicator was obtained from the Newton hybrid for the interphase period of flowering-milk ripeness on fertilized variants was between 9.79 and 10.23 thousand m/ha, against 7.07 thousand m/ha on the control variant. The photosynthetic potential was the highest hybrids (1924.91 and 1956.91 thousand m x day/ha for the option of N60P54K168 and 2039.84 and 2066.31 thousand m x day/ha for the N180P154K294). Consequently, the planned yields of green mass were obtained on crops of hybrids Flint-200 and Newton 42,9 and 43.9 t/ha with the introduction of calculated doses of mineral fertilizers at 50 t/ha and 62.6 and 65.3 t/ha against the background of mineral fertilizers at 70 t/ha. Based on the calculations of economic efficiency, it follows that the cultivation of the Newton hybrid against the background of making NPK at the highest cost (28151.5 RUB/ha) and the lowest cost of 1 ton of green mass of corn (431.1 RUB) provides a greater net income (11028.5 RUB/ha) with the best level of profitability (39.2 %).


Introduction
Cornis very responsive to photoactive radiation, which contributes to the intensive accumulation of biologically active substances. However, it should be noted that the culture of corn in a broad sense, along with this feature, is also responsive to soil and climatic conditions, where optimal nutritional parameters play a crucial role in obtaining high productivity [1,2].
Experiments with the use of mineral fertilizers in corn crops are carried out not only in the regions of the Russian Federation [3][4][5], but also on other continents [6,7].
Along with the biological features of corn hybrids and weather conditions, according to Sidelnikova N.A. and Smirnova V.V., plant density and mineral fertilizers had a smaller impact on the leaf surface area [5].
On the leached chernozem of the Stavropol Upland, fertilizer doses of the brand N17Р17К17, regardless of the method of fertilizer, increased the area of the leaf surface of corn for silage [8].
In the conditions of the Volga region of the Republic of Tatarstan, the largest increase in the leaf surface occurred in the crops of the Flint hybrid -200 [9].
Comparing the data on the effect of mineral nutrition on the indicators of chlorophyll activity and corn productivity, the level of increase in corn yield resulting from application of fertilizers was significantly higher than the level of increase in photosynthetic activity of chlorophyll. There was a noticeable increase in corn productivity. The collection of its dry matter increased by 43 %, and the yield of green massby 24 %. The yield increase occurs as a result of the redistribution of photosynthesis products in favor of the above-ground mass [10].
The complex use of macro-fertilizers in background of as a supplement to liming and pre-sowing treatment of seeds with zinc-containing compounds increased the coefficient of productivity of photosynthesis to 2.03 %, from 0.56 % in tropical Africa [11].
The use of high-efficiency fertilizers, such as urea with a polymer coating, can be a good option for managing nitrogen to increase the yield of corn, improve grain quality and reduce nitrogen in the soil [12].
In North Dakota, a positive response of corn yield to potash fertilizer application (K130 and K200) was revealed at 25 sites [13].
Macroelements were calculated by calculation and balance method, taking into account soil fertility for the planned yield of green mass 50 (N60P54K168) and 70 t/ha (N180P154K294). The repetition is threefold.
Samples of plants were collected in phases of 7-8 leaves, flowering and milky ripeness of corn grain. Leaf surface area was calculated by die cutting. The photosynthetic potential (AF) and its productivity were calculated by the method of Nichiporovich. The net productivity of photosynthesis (PPF) was determined by the increase in the dry mass of plants, attributed to the leaf surface area during the reference period [14].

Results
The most important indicator of the formation of a crop of green mass of corn is the leaf area. The average amount of mineral fertilizers in the flowering phase over three years ensured an increase in leaf area by 2.6-9.82 thousand m 2 /ha in the variant with introduction of NPK at 50 t/ha N60P54K168 and (70 t/ha) 4.85-14.56 thousand m 2 /ha in N180P154K294 ( Table 1).
The greatest responsiveness to improved nutrition was revealed in Koenigs and ROSS-140 hybrids. In the phase of milk maturity, the leaf surface area on the fertilizer application in the calculation of 50 t/ha of green mass was 47.59 thousand m 2 /ha and 38.37 thousand m 2 /ha, respectively. In one versionthe planned production of 70 t/ha of green mass of corn, the leaf area of the Koenigs hybrid was 48.38 thousand m 2 /ha, and in the ROSS-140 hybrid -42.92 thousand m 2 /ha. Less responsiveness to the reception of intensification was revealed in the Flint -200 hybrid.
The trend of positive responsiveness of corn hybrids to the application of mineral fertilizers has been preserved in terms of the increase in leaf surface during the interphase periods of culture development.
The growth of the Newton hybrid leaf surface for the interphase flowering periodmilky ripeness on the 50 and 70 t/ha mineral fertilizer application options amounted to 9.79 and 10.23 thousand m 2 /ha. Without fertilization, the growth of the leaf surface during the period of intensive growth of corn by hybrids was: Krasnodar -194-18.75 thousand m 2 /ha, Flint -200-26.01 thousand m 2 /ha, Koenigs -25.24 thousand m 2 /ha, ROSS -140-13.08 thousand m 2 /ha, Newton -23.89 thousand m 2 /ha. The values of this indicator against the background with the introduction of mineral fertilizers at 50 t/ha were higher on average by 5.5 and against the background of the application of NPC at 70 t/ha it was 6.1 thousand m 2 /ha. There is a direct relationship between the photosynthetic activity of the leaves and the accumulation of dry matter by plants, which subsequently affects the increase in yield ( Table 2).
The number of "working days" of the leaf surface during vegetation on a windy background was the limit from 1125. The introduction of macronutrients increased both the leaf surface area and the indicator of the photosynthetic potential of corn leaves. The introduction of macronutrients increased both the leaf surface area and the indicator of the photosynthetic potential of corn leaves.
During the growing season, the maximum values of the net productivity of photosynthesis of corn among fertilized varieties were in hybrids Krasnodar -194 and Flint -200 or 4.00 and 4.08 g/m 2 when planning production of 50 t/ha of green mass, 5.38 and 5.35 g/m 2 when making N180P154K294.
Against the background with in the variant with introduction of NRK at 50 and 70 t/ha, high yield of green mass was obtained from Flint hybrids -200 (42.9 and 62.6 t/ha) and Newton (43.9 and 65.3 t/ha).
The lowest yield on the same background was obtained when the Koenigs hybrid was sown at 35.3 t/ha (N60P54K168) and ROSS -140 -56.9 t/ha (N180P154K294).
For applying NPK at 50 t/ha, the yield increase by hybrids was a limit of 12.4 to 18.7 t/ha with a maximum value for the Flint hybrid -200 and a minimum value for the Koenigs hybrid.
When NPK was applied at 70 t/ha (N180P154K294), the increase in yield of green mass in the cultivation of the Krasnodar hybrid -194 was 35.6 t/ha; hybrid ROSS -140 -34.3 t/ha and in hybrid Newton -37.2 t/ha. Improving the nutrient regime of the soil in the cultivation of maize for green mass by applying mineral fertilizers was economically beneficial (Тable 4).
On the variant without fertilization the main indicators that characterize the economic effect were the hybrid within the following limits: the value of the crop from 13560 to 16860 RUB for 1 ton, the costs of 11515.0 to 13499.9 RUB/ha, the cost of 1 ton of green mass from 480.4-502.9 rubles, net income from 2225.0 to 3360.1 RUB/ha, profitability level from 19.3 to 24.8 %.
A greater economic effect on this option was obtained during the cultivation of the Newton hybrid. In the NPK variant, the economic efficiency indicators increased by almost half by 50 t/ha and 70 t/ha. When you make N60P54K168 50 t/ha less the cost of the resulting product was a hybrid Newton -437. 5

Conclusion
The application of mineral fertilizers at 50 and 70 t/ha in the cultivation of corn for green mass provided an increase in the leaf surface area by 11.01 and 15.56 thousand m 2 /ha, compared to the background without fertilizers.
The photosynthetic potential was maximum for the Flint hybrids -200 and Koenigs (1924.91 and1956.91 thousand m 2 x day/ha) on the NPK introduction variant at 50 t/ha (N60P54K168) and against the introduction of NPK at 70 t/ha (N180P154K294) 2039.84 and 2066.31 thousand m 2 x day/ha. Planned green mass yields were obtained from the Flint-200 and Newton hybrids 42.9 and 43.9 t/ha against the introduction of NPK for 50 t/ha to 62.6 and 65.3 t/ha against the application of mineral fertilizers for 70 t/ha.
Based on the calculations of economic efficiency, it follows that the cultivation of the Newton hybrid against the background of making NPK at the highest cost (28151.5 RUB/ha), and the lowest cost of 1 ton of green mass of corn (431.1 RUB), provides the highest net income (11028.5 RUB/ha) with the best level of profitability (39.2 %).