OPTIMISATION OF PLANT DENSITY OF TETRAGONOLOBUS PURPUREUS (TETRAGONOLOBUS PURPUREUS MOENCH.)

Abstract

Objective. To determine the optimal sowing density of tetragonolobus to achieve maximum productivity and improve product quality. Methods. The study was conducted using a set of methods, including field experiments, laboratory studies and statistical analysis of data. Results. The study showed that the sowing density had a significant impact on the productivity and quality of tetragonalobus. At the lowest sowing density (89 thousand units/ha), the highest plant productivity (43.9 g) was achieved. With increasing density, productivity decreased. The most effective was the sowing scheme of 45 x 10 cm, which provided the maximum yield of spade beans (6.2 t/ha), exceeding the control by 6.9%. Increasing the distance between plants in the row led to a decrease in yield, especially with the 45 x 20 cm and 45 x 25 cm sowing scheme, where the yield was 22.4‑44.2% lower compared to the control. The 45 x 25 cm sowing scheme provided the highest content of total nitrogen in the beans (3.2%). With increasing sowing density, this indicator decreased, reaching a minimum (2.7%) at a density of 45 x 10 cm. Sowing density of 89 and 111 thousand units/ha provided a high dry matter content, exceeding the control by 1.8–3.3%. At the same time, at a density of 222 thousand units/ha, the dry matter content was the lowest, 2.8% lower than the control. The high content of total sugars (7.4–7.7%) was observed at a sowing density of 89 and 111 thousand units/ha. With increasing density, the sugar content decreased. The maximum content of vitamin C (38.5 mg/100 g) was found at a density of 89 thousand units/ha, and the minimum (30.8 mg/100 g) – at 222 thousand units/ha. A clear negative relationship between sowing density and productivity of one plant was found (r=-0.98). The yield initially increased with increasing density, but then began to decline. The content of total nitrogen, dry matter, total sugars and vitamin C also decreased with increasing sowing density (correlation coefficients from -0.96 to -0.99). Conclusions. The highest yield of tetragonolobus beans was achieved with a planting pattern of 45 x 10 cm, which corresponds to 222 thousand units/ha. It is at a sowing density of 89–111 thousand units/ha that the maximum amount of biologically active substances accumulates in the beans. There is a negative correlation between sowing density and productivity of one plant. A curvilinear relationship between the density of sowing of tetragonolobus and bean yield was found. With increasing sowing density, bean yield first increases, then reaches a maximum and begins to decline. Increasing the number of plants per unit area negatively affects the biochemical parameters of beans.