Genotype × environment interaction and yield stability analysis of some cowpea varieties released in Ghana from 1990 to 2005

Abstract

The phenological development, growth, yield and yield stability performance of eight cowpea varieties released in Ghana between 1990 and 2015 were evaluated in field experiments carried out at Mampong-Ashanti (forest-savannah transition zone) and Fumesua (forest zone) over two cropping seasons in 2015 and 2016. The experiments were arranged in a randomized complete block design (RCBD) with three replicates. Asontem, Nhyira, Asetenapa, Hewale and Videza flowered and podded earlier (37-44 days and 49- 51 days, respectively) than Soronko, Tona and Asomdwe (46-48 days and 52-55 days, respectively). Hewale, Asomdwe, Asontem and Videza by virtue of their erect and semierect architecture had the highest plant height in both seasons, while Tona recorded the lowest. Crop growth rate among the varieties ranged from 1.1-1.7 g/m2/day for Asetenapa, Tona and Videzea to 2.3-3.3 g/m2/day for Asontem, Nhyira, Soronko, Hewale and Asondwe. Pod yield ranged from 980-2540 kg/ha, with Videza and Soronko producing the lowest pod yields, while Asontem had the highest pod yield across both locations and cropping seasons. Seed yield ranged from 603-2241 kg/ha, with Asetenapa yielding the lowest (603-1407 kg/ha). Asontem produced the highest number of pods per plant and number of seeds per pod and thus the highest seed yields (1240-2241 kg/ha) over the locations and seasons. Pod harvest index ranged from 0.58-0.90. The four yield stability analysis methods used showed that Asontem and Tona were the most stable varieties and were adapted to all the environments, while Soronko and Asetenapa were the least stable and were adapted to more favourable environments.