EFFECTS OF FOLIAR FERTILIZATION ON YIELD AND SEEDS QUALITY AT THE STAGES OF PRIMARY SEED MANAGEMENT IN WINTER WHEAT

Abstract

Fertilizers are one of the most effective ways to improve soil fertility, increase yields, improve quality of grain and seeds. According to EG Dehodyuk, phosphate and potassium fertilizers increase crop resistance against fungal diseases.

Scientific research and practice have proved that chemical fertilizers at the main cultivation contribute not only to increase in yield, but also significantly improve sowing quality of seeds. However, fertilization at the main cultivation is not always sufficient to produce high-quality seeds and realization of genetic potential of new varieties. This can be achieved through foliar top-dressing seed crops of winter wheat with nitrogen fertilizers at different stages of organogenesis. In this regard, we study the effects of foliar top-dressing crops of breeding nursery first and second years (P-1 and P-2) by ammonium nitrate (NH₄NO₃) against the background N₃₀P₇₈K₇₈.

In the development of winter wheat are two critical periods of nutrients supply: the first - from germination to the termination of the autumn growing season when plants are sensitive to the deficit of nitrogen and phosphorus, and the second - from the beginning of spring vegetation restoration to the grain filling. Therefore, the different variations of nitrogen fertilizers in these critical periods of the growing season of winter wheat was envisaged in our research.

Top-dressing crops of breeding nursery P-1 and P-2 at early stage of stem elongation ensured the best growth, development of plants and shoot density.

Number of plants per 1 m² in the studied varieties under seeding rate of 5.5 million/ha and sowing in September 20 differed little in the treatments: crop of variety Smuhlyanka without top-dressing before heading has on average 387 - 403 plants per m², variety Podolyanka - 398 - 405 plants per m². However productive shoots density varied greatly: for variety Smuhlyanka it was 721 stems per m²on background fertilizing without top-dressing, 750 stems per m²for the first top-dressing N₂₀ and 863 stems per m² for the second one. In variety Podolyanka these figures were respectively 687, 722 and 806 stems per m², which was 5 - 7% less than in variety Smuhlyanka. The winter wheat plants with a double top-dressing before heading have more developed a vegetative mass and root system.

Third top-dressing in a dose of N₃₀ in period heading – grain filling negatively affected the crops. On the background of excess rainfall in late May and early June of 2014 of almost 1.5 times to normal, this led to a significant lodging of plants. As a result, there was an affection of seed crops by fungal diseases (brown rust, powdery mildew and Septoria leaf blotch). All these have led to a partial reduction in productivity and production of certified seeds in variety Smuhlyanka. and significant in variety Podolyanka.

In the background treatment (N₃₀P₇₈K₇₈ - control) without top-dressing, grain yield and production of certified seeds averaged over three years (2013-2015) were virtually the same: 6.9 and 6.8 t/ha for grain yield and 5.9 and 5, 10 t/ha for yield of certified seeds. However in the unfavorable 2013 year, variety Podolyanka responded less to weather conditions and its grain yield was 5.3 t/ha and yield of certified seed – 3.87 t/ha, that were 1.8 and 1.29 t/ha more than in variety Smuhlyanka. Reduced grain productivity and production of certified seeds in a variety Smuhlyanka can be explained by the fact that high-intensity type of semi-dwarf varieties in dry years are less responsive to fertilizer than tall intensive varieties.

Three foliar nitrogen application compared to the background fertilizer (control) significantly increased the yield and gain of certified seed in variety Smuhlyanka (4.9 - 18.3%), in the treatment background (control) + N₂₀ - the increases were lower (9, 0 - 12.7%), in treatment background + N₂₀ + N₃₅ - changes were negative (-3.3%). In variety Podolyanka these figures were much lower and amounted respectively - 5.5 - 16.5%; from 8.6 to -1.7% and -9.4%. Reducing the production of certified seed in variety Podolyanka by top-dressing in period heading – grain filling can be explained by higher lodging and plant diseases lesions compared with the variety Smuhlyanka.

Weight of 1000 seeds. In the years with favorable weather conditions (2014-2015) increases in weight of 1000 seeds due to foliar nitrogen fertilization were insignificant and the values amounted in variety Smuhlyanka 46.5 + 0.3 g, in variety Podolyanka 48.6 + 0.4 g In average for three years (2013-2015) the weight of 1000 seeds was higher in variety Podolyanka and amounted 47.2 grams versus 45.3 grams in variety Smuhlyanka.

According to research data root dressing by ammonium nitrate on the background of complete mineral nutrition improves performance vigor and laboratory seed germination. Exceptin is the third top-dressing in heading-grain filling period, which led to a partial lodging of plant variety Smuhlyanka (0.3 points) and strong lodging in variety Podolyanka (2,0-2,5 points). This led to the loss of laboratory seed germination in variety Smuhlyanka by 2%, which still  remained certified, and in variety Podolyanka by 7-8%, resulting in loss of seed quality certificate (89% germination).

Conclusions. The research data suggests that on the background of complete mineral nutrition (N₃₀R₇₈K₇₈) applied under main cultivation, foliar feeding by ammonium nitrate at different stages of ontogeny plants differently affects the formation of grain yield and sowing quality of seeds in crops of breeding nursery P-1 and P-2 of varieties of different growing intensity. Thus, the first spring top-dressing at tillering stage in dose of N₂₀ facilitated plants vigor, additional tillering and increasing the shoot and root weight. The second top-dressing in a dose of N₃₅ on stem elongation stage provided better plant growth and development and increased shoot density steblestoyu, especially in less intensive variety Podolyanka.

Third top-dressing in a dose of N₃₀ in period of heading-grain filling resulted in a small decrease in variety Smuhlyanka and significant in variety Podolyanka not only yield, but also sowing qualities of seeds. This can be explained both lodging and plant affection by fungal diseases.