Correlated response and path analysis of some growth characters to grain yield in rainy season sorghum (Sorghum bicolor (L.) Moench) varieties at Samaru and Maigana Northern Guinea Savannah

Abstract

Correlation and path analysis was evaluated in 2013 and 2014 wet seasons at the Research Farm of the Institute for Agricultural Research (I.A.R) of Ahmadu Bello University, Zaria, and Kaduna State Agricultural Development Agency, Maigana for seven characters (plant height, number of leaves, leaf area index, crop growth rate, relative growth rate and net assimilation rate). Two sorghum varieties were grown at four rates of cowdung (0, 5, 10 and 15 t ha^-1) and inorganic nitrogen (0, 30, 60 and 90 kg N ha^-1). Treatments were laid out in a split plot design and replicated three times with nitrogen and cowdung rates assigned in the main plot while varieties were allocated to sub-plots. Grain yield had expressed highly significant and positive correlation with all the parameters in both years, locations and combined except net assimilation rate (0.156), (0.186) at Samaru in 2013 and combined seasons respectively and at Maigana (0.190) in the combined years of the experiment only. The variables that had the strongest positive direct effects on grain yield at Samaru in both years was plant height (0.918), (0.922) except the combined years, where leaf area index (LAI) had the strongest relationship (0.186) while at Maigana number of leaves had the strongest relation (0.746) in 2013 but LAI was the strongest (0.906) and (0.847) in 2014 and combined years respectively. The effects of the other variables were not consistent in both seasons, locations and combined. The highest total percentage contribution to yield at Samaru in 2013 was by LAI (277.15%) while in 2014 and combined seasons was by Plant height (196.21%) and (56.76%) respectively. The highest total percent contribution to yield at Maigana in 2013 was by number of leaves per plant (134.08%) while in 2014 and combined seasons was by plant height (53.56%) and (76.13%) respectively. The interrelationships among these variables might be used in preparing a breeding programme to take advantage of their contributions to yield and develop high yielding sorghum varieties of improved characteristics.