Irrigation water requirement of hybrid maize grown on Rhodustalfs in Sri Lanka

Maize (Zea mays L.) is the second important cereal crop, which can be grown successfully in many parts of Sri Lanka under rainfed and irrigated conditions. Among the farmers, hybrid maize varieties are most popular than open pollinated varieties (OPV). However, at present irrigation recommendation is available only for OPV maize in Sri Lanka. Field experiments were conducted to study the effect of different irrigation water levels applied at different growth stages on maize seed yield in Rhodustalfs soil. The five different irrigation water (IW)/cumulative pan evaporation (CPE) ratios, 0.7, 0.85, 1, 1.15 and 1.3 were selected. These irrigation ratios were applied at different stages (1^st, 2^nd and 3^rd month growth stages) of hybrid maize and in year 2010 variety Sampath and 2011 in 2013 variety Pacific 999 super was used. Altogether thirteen treatment combinations were tested with three replications in Randomized Complete Block Design. The result revealed that the highest seed yield (9.3 t/ha -var. Pacific 999 super) was recorded by the treatment combination of 0.85, 1.15, 1.15 ratios supplied at three different stages, respectively and this was not significantly different to ratios of IW/ CPE 0.7, 1.15 and 1.15 supplied at the same stage. This combination consumed average of 430 mm of water giving water productivity of 2.1 kg/m³. There was a significant yield reduction when the IW/ CPE ratio was below 1.15 at 2^nd month (flowering stage). Hence, the IW/ CPE ratio of 0.7, 1.15, 1.15 in 1^st, 2^nd and 3^rd months could be recommended to achieve high yield in hybrid maize grown on Rhodustalfs soil.