Grain Yield Performance of CIMMYT Maize Germplasm Under Low Nitrogen Soil Conditions In The Mid Altitude Sub Humid Agro-Ecology of Ethiopia

摘要

Nitrogen is one of the factors that frequently limit maize production in tropical areas like Ethiopia (Worku et al., 2002; Oikeh et al., 1997; Sanchez, 1976). As a result, large quantities of nitrogenous fertilizer must be applied as a basic input in order to achieve satisfactory yields in the country (Ransom et al., 1993). Nevertheless, it is difficult to sustain this crop management system over the long run, given the high costs of fertilizers (Negassa et al., 1997). Different maize varieties (Hybrids and OPVs) in different sets of trials were evaluated under low-N and optimum-N conditions at Bako from 2001 to 2005 in the main cropping season in alpha lattice design in collaboration with CIMMYT AMS project to identify varieties which can give reasonable yield under both fertility conditions. Grain yield, reaction to diseases and ears per plant were considered in selecting the varieties. Separate analysis of variance for grain yield was done for each trial and it showed significant difference (P＜0.05) among the varieties. The result indicated that, when the top yielding materials under optimum nitrogen level in each trial was selected, the mean yield loss across the trials and years under the low-N condition was high (66%) and when the best materials under low-N condition were selected, most of them were less responsive under the optimum condition. When performance under both fertility levels was considered the mean yield loss across trials and years under low N was 46%. In most cases the varieties also significantly out yielded the local checks under optimum-N levels. These show the presence of genetic variation among the tested materials for the efficiency of nutrient utilization and the possibility of releasing nutrient-use-efficient commercial varieties in Ethiopia. Therefore, better performing materials under both fertility conditions were selected for further evaluation across locations and under farmer conditions.