Evaluation of water use for drought tolerance in Maize (Zea Mays L) Genotypes under deficit irrigation

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Mooya, Dennis
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The problem of drought and erratic rainfall, coupled with crop genotypes (both local and improved varieties) with low water utilisation efficiencies, are major contributors to low productivity of most crops. The poor agricultural productivity among the farming community results in poverty and food insecurity at national level and in low household incomes. Selection of drought adapted genotypes in breeding programmes and efficient use of water are among the most important approaches in combating climate change effects like droughts and erratic rainfall. This study was conducted to characterise drought tolerance of twelve maize genotypes. An experiment was set up at the National Irrigation Research Station in Mazabuka, to determine the response of these genotypes to three water regimes at 30 %, 60 % and 100 % of crop water requirement (ETc). The twelve maize genotypes were planted at each water regime in a split – plot design arranged in a randomized layout. To evaluate the water utilisation of each maize genotype, water use efficiency, crop water productivity, crop yield response factor and harvest index were determined from the grain yield, above ground biomass and data collected during the experiment. Deficit irrigation (30 % and 60 % ETc) resulted in crop yield reduction and significant effects on most of the measured parameters. Anthesis – silking interval was shortened, plant girth and height equally decreased with increased water stress at 30 % of ETc. The results showed variations in maize yield and this was attributed to genotype and water regime. The genotypes and water regimes contributed to yield by 30 % and 50.2 %, respectively. The grain yield in genotypes L512, L353, L857 and L07 had a yield advantage of 36.8 %, 34.6 %, 27.6 % and 18.0 %, respectively above the overall mean. Water Use Efficiency (WUE) at 30 % water regime was high in maize genotypes L512, L60, L713 and L857 with 2.412, 1.818, 1.900 and 2.265 kg/mm/ha, respectively. The Crop Yield Response Factor of genotypes L353, L512, L07 and L857 at 60 % water regime were below 1.0 indicating an efficient water use by most genotypes at 60 % water regime which resulted in a seasonal accumulative value of 505.3 mm for the season under study. Based on the results, genotypes L512, L857, L07 and L353, were selected as drought tolerant genotypes.
Corn-Drought tolerance