Intraspecific-cross compatibility in cowpea (Vigna unguiculata (L.) Walp.)

ABSTRACT The success of any hybridization outcome in cowpea is dependent on temperature and humidity, which affect flower initiation, pollen fertility and pod setting. The purpose of this study was to determine the optimal environmental parameters (temperature and humidity) favorable for a successful hybridization outcome in selected cowpea accessions. A total of 512 reciprocal crosses were made between TVu 11953 and Ife Brown cowpea accessions, in the mornings (299 crosses) and evenings (213 crosses). In 2014, 115 crosses were made in the morning, and 71 in the evening. In 2015, 184 crosses were made in the morning and 142 in the evening. Relative to pod set, the morning crosses were significantly more successful (18.73% success; n = 56) than evening crosses (4.69% success; n = 10), regardless of the mother plant (χ2 = 32.06, p < 0.01). Although pod set differed between mother plants significantly (χ2 = 17.28, p < 0.01), 71.03% viable hybrid seeds were obtained following hybridization. Hybridization outcomes were also significantly influenced by the interactions between genotype, temperature and humidity in the study. Temperature ranging from 26.8°C to 27.9°C and humidity from 82% to 86.4% were favorable for pod set. Utmost attention, therefore, should be given to temperature and humidity for achieving success in making intraspecific crosses in cowpea.