Ecological stability, plasticity, and adaptability of cowpea varieties (Vigna unguiculata (L.) Walp. subsp. sesquipedalis (L.) Verdc.)

Abstract

Determining the ecological plasticity and stability of varieties and hybrids of agricultural crops helps to comprehensively assess them, considering the productivity potential, qualitative technological indicators, and the level of resistance to stressful conditions. The purpose of this study was to investigate the development of the yield of beans of cowpea varieties with high ecological stability, plasticity, and adaptability. The leading methods of studying this problem are field-based – to determine the interaction of the research object with biotic and abiotic factors; statistical – to evaluate the results to determine the parameters of cowpea adaptability. Within the studied varieties, a direct and inverse correlation was established between the yield of cowpea and the sum of effective temperatures. For Groik (r = 0.36) and Kafedralna (Control) (R = 0.36), U-Cha-Kontou (r = -0.64) varieties, the correlation was average, while for Gasson (r = 0.96) and American improved (r = -0.98) varieties, it was strong. Based on the regression equations, an increase in the amount of precipitation by 1 mm can increase the yield of cowpeas by 3.4 kg/ha in the American improved variety and by 20.8 kg/ha – U-Cha-Kontou, and for the Gasson, Kafedralna (control), Groik varieties, there will be a decrease in yield by 6.4 kg/ha, 10.8 kg/ha, and 20.7 kg/ha, respectively. Varieties with high overall adaptive capacity, defined as the ability of genotypes to maximise the manifestation of traits under all environmental conditions, are valuable. High indicators of total adaptive capacity for plant yield were observed in the varieties Gasson (TAC = 5.16) and Groik (SAC = 2.16). The lowest value of this indicator was observed in the U-Cha-Kontou variety (TAC = -3.44). Varieties that produce high but unstable yields are not able to guarantee maximum yields in conditions of improper farming and difficult climatic conditions. The genotype breeding value is a complex indicator that determines the totality of productivity and stability of varieties. Studies have obtained such fluctuations in this indicator from 0.84 to 13.63. The best varieties in terms of genotype breeding value were Gasson (GBVi = 13.63) and Kafedralna (GBVi = 8.06). There is a relatively low yield stability and the ability to respond to improved growing conditions in the U-ChaKontou variety (GBVi = 0.84)