Effect of drought length on the performance of cabbage (Brassica oleracea var capitata) in the forest-savannah transition zone, Ghana

The drought tolerance of Cabbage, Brassica oleracea var capitata (Oxylus) was investigated by subjecting the initial, development and mid growth stages to varying drought lengths of 5, 7, 9, 11, 13 and 15 days in a 7 x 3 factorial experiment to determine the effect of each drought period at each growth stage on growth and yield. Data on number of opened leaves/plant, leaf area index (LAI), leaf chlorophyll content, head size and yield/ha were recorded due to drought effect at each growth stage. Analysis of variance at 5% probability level indicated that drought periods of 5-15 days at the initial stage significantly reduced number of leaves, LAI and head size. Significant reduction in chlorophyll content and yield were due to drought beyond 11 and 5 days respectively at the initial stage. Number of opened leaves increased significantly with increasing drought length at the development stage; critical at 11 days drought. Significant reductions in LAI at the development and mid stages were critical at 11 and 9 days respectively whilst chlorophyll content was significantly reduced at both the development and mid stages by all drought periods. Significant reduction in head size at the development and mid stages was critical at 7 days. Generally, the drought tolerance of cabbage increased from the initial to the mid-stage. To maintain economic yields of cabbage in the forest-savannah transition zone, the initial and development stages could tolerate drought stress up to 5 days whilst the mid stage could tolerate up to 7 days.