Screenhouse evaluation of atrazine for soil residual activity on growth, development and nutritional quality of okra (Abelmoschus esculentus Moench) in southwestern Nigeria

Atrazine is still by far the most widely used herbicide for selective weed control in maize in southwestern Nigeria following which vegetable crops may be sown to 'catch' remaining moisture under rainfed multiple cropping. This study examined under screenhouse conditions the effects of soil residual activity of atrazine at the recommended dose of 3.0 kg a.i. ha−1 on the growth, development and nutritional quality of okra at intervals of 0, 3, 6, 9 and 12 weeks after treatment (WAT). Results indicated that atrazine significantly (P<0.05) reduced plant height, total crop leaf area, and pod fresh weight in all the herbicide treatments relative to the control, but leaf number remained unaffected. Plant height, among other yield and nutritional quality indices, was found to be linearly and positively correlated with time interval between atrazine applications (P⩽0.001; r=+0.98). The results of proximate analysis and determination of Vitamin C content of matured okra pods showed significant reductions in the levels of protein, fat, ash, crude fibre, carbohydrate, Vitamin C, calcium, iron, and moisture content in all the treatments involving atrazine application compared with control. It was concluded that okra should not be sown after maize in which atrazine has been used in order to avoid crop injury and reduced yield of pods with low nutritional value.