Effect of environmental conditions on the genotypic difference in nitrogen use efficiency in maize
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.