Effect of weed residues on growth, tuber yield and leaf nutrient content of yam in Southwest Nigeria

Abstract

Experiment was conducted to evaluate the effect ofmulching with residues of Mexican sunflower (Tithonia diversifolia), Siam weed (Chromolaena
odorata), Elephant grass (Pennisetum purpureum), and Guinea grass (Panicum maximum (Jacq)) on yam (Discorea rotundata) growth parameters, tubers yield, leaf nutrient content and soil physical properties at two locations in Southwest Nigeria. These mulch residues were applied at 10 t/ha making a total of five treatments with the control. The mulches increased vine length, number ofbranches and leaves tuber weight, leaf N, P, K, Ca and Mg contents significantly (P<0.05). Mexican sunflower and Siam had similar effect, likewise Guinea grass and Elephant grass. Soil moisture for plots treated with Mexican sunflower, Siam weed, Elephant grass, Guinea grass and control were 9.95, 9.1, 8.6, 7.7, 6.9% respectively,. Mexican sunflower most conserve soil temperature, followed by Siam weed, Elephant grass and Guinea grass. There were no significant differences in bulk density of soil treated with mulch at Akure, while Mexican sunflower had the least value ofbulk density at both site.