Evaluation of 41 Cowpea Lines Sown on Different Dates in Southern China

Cowpea is an important leguminous crop in arid and semi-arid tropical regions. However, it is sensitive to the temperature and photoperiod. In this study, 41 new lines of cowpea were evaluated in sowing seasons of spring (SpS), summer (SuS), and autumn (AuS) at Wuming, Guangxi province, China. Nine agronomic and yield-related traits were investigated and analyzed. The results showed that the pod width (0.8 cm) was similar among sowing seasons. For all other traits, the values were lowest at SuS, except the number of branches per plant, which was lowest (2.5) at AuS. Strong correlations were detected for the growth period, plant height, pod length, pod width, and 100-seed weight (p < 0.01) across the sowing seasons. A principal component analysis revealed that the first three components could explain 72.47% of the total variations. On the basis of the possible yield, growth period, and growth habit, we identified nine new lines suitable for different sowing seasons in Guangxi. The results of this study suggest these new cowpea lines may be useful for increasing crop production and for breeding new varieties.