EFFECT OF NITROGEN ON GROWTH AND YIELD OF OKRA VARIETIES (Abelmoschus esculentus L.) GROWN IN THUA THIEN HUE

Abstract

The experiments were conducted in a three-replicate split-plot design of 2 × 4 treatments, with variety as the main plot and nitrogen fertilizer application as the sub-plot. Four nitrogen rates: 60, 90, 120, and 150 kg/ha and two varieties: the local variety and the F1 variety, were investigated. The results show that nitrogen significantly affects the stock diameter at 37-day planting, fruit diameter, length, number per plant, weight, theoretical yield, and actual yields of both varieties. However, the interaction between fertilizer and variety is insignificant for all parameters. Nitrogen fertilizer at 150 kg/ha increases the plant height, the number of leaves per plant, and the yield of both varieties, whereas the 60 kg/ha rate shows the lowest value of these traits. More diamondback moths and Green worms are found on the F1 variety than that on the local variety. Nitrogen does not affect the pests that harm the plants of the F1 variety. It is recommended to apply 150 kg/ha of nitrogen for okra grown in the Winter-Spring season.