Effects of time of nitrogen application and frequency of weeding on the performance of okra (Abelmoschus esculentus) in southwestern Nigeria

Abstract

A two – year field experiment was carried out at the Teaching and Research Farm of the University of Ado – Ekiti, Nigeria, during 2005 and 2006 cropping seasons to evaluate the effects of time of nitrogen application, frequency of weeding and the interactions between these two treatments on the growth and yield of okra. The design was a split - plot arrangement, laid out in a randomized complete block, with three replications. Nitrogen application constituted the main – plot treatment, which were: no nitrogen (control); single dose N application at four weeks after planting (WAP); split N application, with half applied at 4 WAP, and the rest at 6 WAP, and single dose N application at 8 WAP. Weeding frequency was the sub – plot factor, which comprised: no weeding (control), weeding once at 3 weeks after planting (WAP), and weeding twice at 6 and 9 WAP. The results obtained indicated that there were significant differences (P ≤0.05) between the treatments in growth and yield parameters of okra. The two – year average values indicated that time of nitrogen application significantly increased okra leaf area from 2.15m2/plant for no nitrogen (control) to 2.71, 2.49 and 2.15m2/plant for single dose N application at 4 WAP, split N application at 4 and 6 WAP, and single dose N application at 8 WAP, respectively. The main effects of weeding on okra leaf area were 2.12, 2.63 and 2.19 m2/plant for no weeding (control), weeding once (3 WAP), and weeding twice (6 and 9 WAP), respectively. Time of nitrogen application significantly increased okra fruit yield from 7.1 t ha-1 for no nitrogen (control) to 10.7, 9.1 and 7.9 t ha-1 for single dose N application at 4 WAP, split N application at 4 and 6 WAP and single dose N application at 8 WAP, respectively. Similarly, weeding significantly increased okra fruit yield from 5.9 t ha-1 for no
weeding (control) to 10.5 and 7.7 t ha-1 for weeding once (3 WAP) and weeding twice (6 and 9 WAP), respectively. The interactions between time of N application and weeding frequency had significant effects on growth and yield components of okra. The treatment combination of single dose N application at 4 WAP and weeding once (3 WAP) resulted in the highest values of growth and yield parameters of okra in both years.