Влияние способов применения азотных удобрений на развитие листовой поверхности растений овса

The article presents the results of field trials conducted on leached chernozem of forest-steppe of the Volga region in 2012-2014. Studied was the development of the leaf surface of filmy varieties (Horizon, Krechet, Eclipse) and naked varieties (Vyatsky, Persheron) of spring oat during the growing season under the influence of nitrogen fertilizers (without nitrogen fertilizers, N60, N60 + N30). The most rapid formation of the leaf apparatus was observed in the filmy oats of Horizon and Krechet varieties in the phase of shooting when nitrogen fertilizers were applied at a dose of 60 kg of active ingredient (30.7-30.3 thousand m2 /ha). However, by the time the panicle was headed, the filmy variety Krechet had almost achieved this value. Naked varieties of oats in comparison with the filmy ones formed a slightly smaller assimilation surface. The use of nitrogen fertilizers had a significant impact on the formation of the assimilation surface of the leaves. However, the additional application of nitrogen fertilizers did not give a significant increase in the leaf apparatus. A higher air-dry mass (94.73 g/m2 ) was formed in the filmy variety Krechet in the phase of milk ripeness against the background of pre-sowing dose of nitrogen fertilizers with additional fertilizing them in the phase of tillering of the culture (variant N60 + N30). Naked varieties of oats were significantly inferior in this indicator to filmy varieties and practically did not differ from each other in the accumulation of dry matter in plants. Only a significant accumulation of dry matter in the Vyatsky and Persheron varieties was noted against the background of applying a pre-sowing dose of nitrogen fertilizers with additional fertilizing them in the tillering phase of the culture (variant N60 + N30). The highest rates of net photosynthesis productivity (NPF) among the studied varieties was observed in filmy varieties in the interphase period "shooting-heading of panicle" against the background of nitrogen fertilizers N60 + N30 (7.17-7.38 g/m 2 ). In naked varieties, this figure was slightly lower than in the filmy ones (6.89-6.90 g/m 2 ). When applying nitrogen fertilizers at a dose of 60 kg active ingredient /ha, there was an increase in the NPF in the interphase period "tillering-shooting " in the following varieties: Horizon by 23%, Krechet by 21%, Eclipse by 15%, Vyatsky by 44%, Persheron by 11%. With the additional introduction of N30 a further increase in the NPF was noted in Horizon by 46%, Krechet by 26%, Eclipse by 42%, Vyatsky and Persheron by 56% relative to the variant without the introduction of mineral nitrogen fertilizer.