Compensatory and Yield Indicators of Oilseed Radish Depending on the Parameters of its Agrocenosis Design

Effective pre-sowing design of crop agrocenoses involves the assessment of possible compensatory mechanisms of plants when changing the nutrition area against the background of corrective fertilization. In order to study such mechanisms and determine the influence of vegetative and reproductive architectonics of plants on the resulting indicators, a five-year cycle of research was conducted on oilseed radish (Raphanus sativus L. var. oleiformis Pers.). The studies used a full range of options for pre-sowing design of oilseed radish agrocenoses from maximum thickening (4 million germinating seeds ha-1 for ordinary row sowing sowing, individual plant nutrition area 25 cm2) to maximum thinning (0.5 million germinating seeds ha-1 for wide-row sowing, 200 cm2). To evaluate the effectiveness of the regulating fertilizer, four variants of it were used: N0P0K0, N30P30K30, N60P60K60, N90P90K90. Based on the use of morphological features of the stem, indicators of the structure of individual seed productivity, correlation and regression analysis, the optimal parameters of formation of oilseed radish agrocenosis were determined. It was based on its ability to intensive lateral productive branching of the stem with a decrease in the seeding rate (increase in the area of plant nutrition, change in the method of sowing), taking into account the growth-stimulating effect of mineral fertilizer. The adaptive compensatory mechanism in oilseed radish plants was established, which ensured the achievement of the maximum level of seed productivity of plants (more than 2.5 t ha-1) in the range of nutrition area of 80–160 cm2 (1.0–1.25 million germinating seeds ha-1 for row sowing on the background of N30-60P30-60K30-60 and 0.80–1.0 million germinating seeds ha-1 for wide-row sowing on the background of N60-90P60-90K60-90). The desired hydrothermal regime with these design parameters provided for an achievable level of precipitation of 260 mm and an average daily temperature for the period April-June in the range of 13–16.5 °C.