Effects of rainfall variability on moisture availability for cultivation of sorghum, kenaf and okra in tropical wet-and dry-climatic western zones of Nigeria

Abstract

Field experiments to determine the effects of moisture availability on the growth and yield of sorghum, kenaf, and okra in sole and  mixtures, were conducted during the 2011 and 2012 cropping seasons at the Federal University of Agriculture, Abeokuta, Nigeria.  Treatments consisted of eleven planting patterns (sole crops, 2-tier mixtures, and 3-tier mixtures) formed from the mixtures of two  sorghum cultivars (Sr and Sw) with kenaf (K) and okra (O) arranged as randomized complete block design with three replications on a  sandy loam soil. Daily agroclimatic data of rainfall, air temperature, relative humidity, bright sunshine hours, day length and wind speed  were collected and processed into decadal means and then related to the various growth components (establishment, vegetative,  reproductive and maturity stages) of the crops. Agronomical data collected were panicle length and grain yield, bast fibre and seed yield,  number of fruits, fruit weight, and fruit yield of sorghum, kenaf, and okra, respectively The results of this study showed that the rainfall  amount received during the 2011 growing period (1018.2 mm) was greater than that during the 2012 growing period (728 mm), but  approximately 71% and 73% were available for crop use, respectively. In addition, only 68.8% and 70.8% of the total rainfall recorded  during the 2011 and 2012 growing periods, respectively, was available for consumptive water use. The water use efficiencies of the crops  in the mixtures were higher than those of their respective sole crops. The yield components of sorghum, kenaf, and okra in both soles  and mixtures were significantly (p < 0.05) higher in 2011 growing period. Based on the values of the water requirement satisfaction index  (> 90%), both seasons were suitable for the cultivation of sorghum/kenaf/okra. The study concluded that the cultivation of crops in  mixtures was suitable for ecological areas with a total annual rainfall of at least 1000 mm.