EFFECTS OF PERCENTAGE LEAF DEFOLIATION AND NPK 15:15:15 FERTILIZER APPLICATION ON THE GROWTH AND YIELD OF CASSAVA (Manihot esculenta (L.) Crantz)

Abstract

Two field experiments were conducted at the Research Farm of the National Root Crop Research Institute, Umudike, Umuahia, Abia State, on the effects of percentage leaf defoliation and NPK 15:15:15 fertilizer application on the growth and yield parameters of cassava (Manihot esculenta (L.) Crantz), TMS 419 sourced from NRCRI. The experiments were laid out in a factorial scheme, using the randomized complete block design (RCBD). The first experiment was laid out as a 4 by 3 factorial scheme with three (3) replications and twelve (12) treatment combinations, giving a total of thirty-six (36) plots in all while the repeat experiment was laid out as a 2 by 3 factorial scheme with three (3) replications and six (6) treatment combinations, giving a total of eighteen (18) plots. The treatments were 0%, 25%, 50%, 75% and 100% for defoliation and 0kg/ha, 150kg/ha, 200kg/ha, 300kg/ha and 400kg/ha for fertilizer applied. The results showed that significant (5%) defoliation effect was observed on plant height when 50%, 75% and 100% rates of defoliation were carried out. Fertilizer applied was only significant when 400kg/ha of fertilizer was applied. Significant defoliation effect (5%) was observed in the number of leaves and also a significant fertilizer effect (5%) was observed in the number of leaves at 150kg/ha. The interaction between them was also significant. Significant defoliation effect (5%) was observed in the number of branches likewise a significant fertilizer effect (5%) was observed in the number of branches at 300kg/ha. Results showed that NPK fertilizer applied had a significant (5%) effect on the leaf area at 400kh/ha. Although with all levels of defoliation, NPK fertilizer applied and their interaction, none showed any significant effect on the yield parameters, but there were some reasonable percentage yield with 200kg/ha to 400kg/ha fertilizer applied.