Abstract

Selection for nitrogen (N) efficient cultivars is typically conducted under favorable field conditions with only difference in soil N availability. However, in practical field conditions, variation in soil types and/or seasonal weather conditions may have a strong influence on plant growth and therefore, N use efficiency. In the present study, a set of 3 genotypes (JD209, JD180 and SM25) were compared for their response to N inputs in two locations with different soil types in 2004 and 2005. It was found that maize yield in Xin-Li-Cheng with black soils was significantly higher than that in Qian-an with light chernozem soil. At the same location, maize yield in 2005 was higher than in 2004 because there was more rainfall in 2005. With sufficient N supplies (150 to 300 kg/ha), no difference in yield potential was observed among the 3 hybrids under the favorable soil and weather conditions. Nevertheless, genotypic difference in maize yield in response to N inputs was observed under varied soil types and rainfall conditions. N-efficient JD209 only showed low-N tolerance under unfavorable soil (light chernozem) and water shortage condition (in 2004). It is concluded that, identification of N-efficient cultivars should be conducted under multiple environments.

Key words: Maize, N efficiency, soil, precipitation.