Evaluation of growth, water balance and water use efficiency of selected maize varieties under rai-fed conditions in Zambia

Abstract

Maize in Zambia is mostly grown under rain-fed conditions with yields strongly correlated to seasonal rainfall pattern. Because of lack of information of maize varieties that use water more efficiently under rain-fed agriculture, achievement of high maize productivity has been difficult. The aim of this study was to evaluate growth, water balance and water use efficiency of selected hybrid maize varieties in Zambia under rain-fed conditions. A field experiment was conducted during the 2014/15 rainy season at the University of Zambia Agricultural Demonstration Centre. The experiment was set up in a Randomized Complete Block Design with three replications. Treatments were 30 maize varieties from the early, medium and late maturity classes. Maize growth parameters and stages important for computing daily growth and development of a crop and dry matter production from emergence to maturity were monitored. Components of the root zone soil water balance were estimated using AquaCrop. The results showed that the duration of the initial, crop development, mid-season, and late-season growth stages of the early maturing maize varieties were 21, 32, 43 and 23 days, respectively. Medium maturing maize varieties took 24, 36, 49, and 26 days for the initial, crop development, mid-season and late-season stages of growth, respectively while late maturing maize varieties took 27 days for the initial development, 41 days for crop development, 53 days for mid-season and 28 days for the late-season growth stage. The aboveground dry matter was 8.96, 10.48 and 14.26 tons ha-1 for the early, medium and late maturing maize varieties, respectively. Results from the experiment showed no significant differences in the aboveground dry matter (P > 0.05) of the early and medium maturing maize varieties while significant differences (P < 0.05) were observed in the aboveground biomass of late maturing maize varieties. In terms of grain yield, early, medium and late maturing maize varieties had 3.26, 3.56 and 4.45 tons ha-1, respectively. No significant differences were observed in grain yield within each maturity class. In terms of water use, the early, medium and late maturing maize varieties had a seasonal crop water consumption of 376.8 mm, 411.8 mm, and 422.9 mm, respectively. Water use efficiency for aboveground biomass among the early maturing maize varieties varied from 16.1 to 32.1 kg ha-1 mm-1; 15.3 to 31.6 kg ha-1 mm-1 for medium maturing maize varieties; and 13.2 to 52.9 kg ha-1, mm-1 for late maturing maize varieties. Significant differences were observed in the water use efficiency for aboveground dry matter of late maturing maize varieties (P < 0.05) but no such differences were observed for early and medium maturing maize varieties. Water use efficiency for grain yield among early maturing maize varieties was in the range 6.2 to 12.0 kg ha-1 mm-1; varied from 5.7 to 11.4 kg ha-1 mm-1for medium maturing maize varieties and among late maturing maize varieties, water use efficiency for grain yield varied from 3.72 to 13.22 kg ha-1 mm-1. However, water use efficiency for grain yield was not significantly different within maize maturity classes. From the study therefore, it can be concluded that differences in growth and grain yield observed could be attributed to differences in use of water by maize varieties. Maize varieties that had high growth vigor yielded more grain and resulted in high WUE. From the findings, it is recommended that maize varieties with high WUE should be grown given the erratic rainfall pattern that usually prevail in the region. This will enhance maize productivity and ensure sustainability.