EFFECTS OF INCREASING MAIZE PLANTING DENSITY IN A CASSAVA/MAIZE MIXTURE AND WEEDING FREQUENCY ON THE PERFORMANCE OF CASSAVA (Manihot esculenta Crantz) IN ADO – EKITI, SOUTHWESTERN NIGERIA

Abstract

A two – year field experiment was conducted at the Teaching and Research Farm of the University ofAdo-Ekiti, Nigeria, during 2005 and 2006 cropping seasons to determine the effects of increasingmaize planting density in a cassava/maize mixture and weeding frequency on the performance of cassava(Manihot esculenta Crantz). The design was a split–plot, laid out in a randomized completeblock, with three replications. Varying maize planting densities constituted the main – plot treatment,namely: sole cropped cassava (10,000 plants ha-1) as the control, and cassava + maize mixture at fourmaize planting densities of 20,000, 40,000, 60,000, and 80,000 plants ha-1. Weeding frequency wasthe sub – plot factor, which included: the control (i.e. no weeding, W0), weeding once (W1), at fourweeks after planting (WAP), weeding twice (W2) at 4 and 8 WAP, and weeding thrice (W3) at 8, 12 and16 WAP. The results obtained indicated that there were significant differences (p≤ 0.05) between thetreatments in respect of growth and yield parameters of cassava. The two-year average values indicatedthat increase in maize planting density resulted in a significant decrease in cassava leaf areafrom 2.74 m2/plant for sole cropped cassava (control) to 2.43, 2.20, 2.02 and 1.74 m2/plant for cassava+ maize mixture at 20,000 maize plants ha-1 , 40,000 maize plants ha-1, 60,000 maize plants ha-1 and80,000 maize plants ha-1, respectively. Similarly, increase in maize planting density resulted in a significantdecrease in cassava tuber weight from 9.71 t ha-1 for sole cropped cassava (control) to 9.24,8.78, 8.27 and 7.80 t ha-1 for cassava + maize mixture at 20,000 maize plants ha-1, 40,000 maizeplants ha-1, 60,000 maize plants ha-1 and 80,000 maize plants ha-1, respectively. Weeding significantlyincreased cassava leaf area from 1.68 m2/plant for W0 to 1.95, 2.01, and 1.80 m2/plant for W1 (4WAP), W2 (4 and 8 WAP) and W3 (8, 12 and 16 WAP), respectively. Similarly, weeding significantlyincreased cassava tuber yield from 4.96 t ha-1 for W0 to 6.35, 8.75 and 5.90 t ha-1 for W1 (4 WAP), W2(4 and 8 WAP) and W3 (8, 12 and 16 WAP), respectively. The interactions between maize plantingdensity and weeding had significant effects on growth and yield of cassava. The treatment combinationof sole cropped cassava (10,000 plants ha-1) and W2 (4 and 8 WAP) resulted in the highest valuesof growth and yield indices of cassava in both years.