Influence of sowing dates on the ecological stability, plasticity, and adaptability of lablab bean (Dolichos lablab L.)

Understanding the effects of soil and climatic conditions on agricultural crops forms the basis for developing and implementing innovative technologies and strategies aimed at minimising negative impacts on farming systems and agriculture as a whole. This study aimed to examine the impact of different sowing dates on lablab beans in order to expand the crop’s cultivation potential in the conditions of the RightBank Forest-Steppe of Ukraine. The following methods were employed to investigate this issue: field trials to study the interaction of the research subject with biotic and abiotic factors and statistical analysis to evaluate the research results and determine the adaptability parameters of the lablab bean. It was established that the highest yield of green pods (2.1 t/ha)was achieved when sowing took place in the first ten-day period of May, which exceeded the control variant (the third ten-day period of April – 1.8 t/ha) by 0.3 t/ha (16.7%). The lowest yield (1.5 t/ha) was recorded when sowing occurred in the first ten-day period of June. The study also revealed that yield was influenced by the length of the growing season (r = 0.68), the sum of active temperatures (>10°C) (r = 0.72), and total precipitation (r = 0.74). A strong positive correlation was established between lablab bean yield and general adaptability (r=0.99), plasticity (r=0.67), homeostasis (r=0.91), and breeding value (r=0.71). Conversely, a negative correlation was observed between yield and the coefficient of variation (r = −0.75) as well as relative stability (r=−0.50). The relative yield stability (Sgi) ranged from 1.45% to 3.74%. The coefficient of variation in yield varied between 11.11% and 17.64%, depending on the sowing date. Under the agro-climatic conditions of the study, high plasticity was demonstrated in the sowing variants from the third ten-day period of April (control) to the third ten-day period of May. A low bi value was observed only when sowing took place in the first ten-day period of June, indicating that the lablab bean exhibited low ecological plasticity. The highest breeding value of the genotype (BVGi =1.09 1.33) was recorded for sowings in the third ten-day period of April (control) and the first tenday period of May, while the lowest value (BVGi = −0.275) occurred with sowing in the first ten-day period of June