ABSTRACT

Field trials were conducted during the 2012 and 2013 rainy seasons at the Teaching and Research Farm of Samaru College of Agriculture, Ahmadu Bello University Zaria and in 2012/2013 and 2013/2014 dry seasons at the Irrigation Research Station, Kadawa of the Institute for Agricultural Research, Kadawa. The treatments consisted of three levels of poultry manure (0, 1.5 and 3 tonnes ha-1), five weed control methods which included three rates of post emergence herbicide (0.054 kg a.i.ha-1, 0.108 kg a.i ha-1 and 0.162 kg a.i ha-1 of Haloxyfop-R-methyl ester), weedy check, and hoe weeding at 3 and 6 weeks after sowing (WAS) and three varieties of groundnut (SAMNUT 11, SAMNUT 22 and SAMNUT 23). The treatments were laid out in a split-plot design with factorial combinations of the weed control methods and poultry manure occupying the main plot while the varieties were allocated to the subplots. The treatments were replicated three times. The results from the study revealed that application of 3.0 tonnes ha-1 poultry manure significantly increased growth parameters such as plant height, shoot dry weight, number of branches, and number of leaves, crop growth rate and relative growth rate. Days to 50% flowering was reduced by the application of 3.0 tonnes ha-1 poultry manure. Application of 3.0 tonnes ha-1 poultry manure improved the crop vigour score of groundnut plant and increased weed control efficiencies. Application of poultry manure increased pod weight plot-1, 100 kernel weight and pod yield ha-1. However, a further increase from 1.5 tonnes ha-1 to 3.0 tonnes ha-1 resulted in significant increase in haulms production at the expense of the yield characters. Among the evaluated weed control methods, two hoe weeding resulted in significant increase in all the growth parameters considered in this work, while days to 50% flowering was significantly reduced by two hoe weeding. Similarly, two hoe weeding resulted in highest crop vigour and highest weed control efficiency. Other weed control parameters such as crop injury, weed cover score, weed dry weight were significantly reduced by the same treatments. All the yield parameters were significantly increased by two hoe weeding. Production of SAMNUT 11 resulted in the highest growth and yield parameters and lowest weed infestation. Pod yield ha-1 was positively and highly correlated with number of branches, number of leaves, plant height, canopy spread, number of pods, pod weight and 100 kernel weight but was negatively correlated with haulm yield. Pod weight had the highest direct contribution which was followed by 100 kernel weight, number of pods, number of branches, plant height and canopy spread in that order, while number of leaves had the lowest direct contribution. The combined effect of pod weight and 100 kernel weight gave the highest combined contribution while the combined contribution of number of branches and number of pods and the combined contribution from number of branches and number of leaves ranked second. The least combined contribution was from number of leaves and number of pods; and plant height and canopy spread that resulted in negative values. The profitability analysis showed that the combinations of 1.5 tonnes ha-1 of poultry manure, two hoe weeding and SAMNUT 11 gave the highest net farm income. It can be concluded that application of 1.5 tonnes ha-1 of poultry manure, two hoe weeding and use of SAMNUT 11 resulted in highest pod yield and profitability of groundnut in the study area.