Seed yield and physiological seed quality of cowpea varieties sown at different planting dates in Minna, Southern guinea savanna of Nigeria.

Abstract

Cowpea is the most important grain legume in Nigeria but its yield has remained low. Inappropriate sowing date as well as use of poor quality seeds by farmers have been identified as part of the factors responsible for the low yields obtained on famers’ fields. A field and laboratory study was conducted to determine the yield and quality of seeds harvested from cowpea varieties planted at different dates within the growing season of 2017. The study was a two factor experiment consisting of nine planting dates (planting at 2 weekly intervals from 19th May to 8th September, 2017) and three cowpea varieties (IT93K-452-1, Oloyin and Kanannado). Data were collected on seed yield, 100- seed weight, germination percentage, germination speed, seedling weight and seedling vigour index. Data collected were subjected to analysis of variance and the treatments means were separated using least significant difference at 5% level of probability. Results revealed that Oloyin variety had the highest seed yield when sown on 19th May. The value was however at par with the seed yield of plants sown on 11th August. Kannanado variety had the highest seed yield when sown on 28th July which was equally at par with the yield obtained when sown on 11th August. IT93K-452-1 equally had the highest seed yield when sown on 19th May which was similar to value obtained in plants sown on1st July followed by the seed yield obtained in plants sown on 14th June and 11th August which had similar values. Seeds obtained from plants sown on 11th and 25 th of August had significantly higher germination percentage, germination speed, seedling weight and seedling vigour index before and during storage than the seeds sown earlier or later in the three varieties. Among the varieties, Kanannado produced the heaviest seeds followed by Oloyin but IT93K-452-1 had the highest seed yield followed by Oloyin and the least seed yield was recorded in Kanannado variety. Though Kanannado variety had significantly higher germination percentage and seedling weight at early storage, IT93K-452-1 had significantly higher germination speed, seedling vigour index and stored better. Oloyin variety had the least values of all the quality indices measured. Therefore, for maximum seed yield and quality, planting around 11th of August is recommended for farmers in the study area and among the varieties tested, IT93K-452-1 is recommended for higher seed yield and quality.