Estimation of quantitative genetic and stability parameters inmaize under high and low N levels

摘要

It is important to breed maize (Zea mays L) cultivars with high performance under variable N levels. We studiedthe effect of N levels and estimated quantitative genetic parameters for grain yield, quality, and other traits, andexamined stability of performance for grain yield in diverse Chinese maize germplasm. From 2006 to 2008, eachyear 20 and in total 30 maize hybrids, including commercial hybrids currently grown in this region and other experimental hybrids as well as high-oil hybrids, were tested using nine environments (location-year combinations)in North China Plain. In each environment, two replicated trials were grown: one under high N application rate(HN, 225 kg N ha~(-1)) and the other under low N application rate (LN, no N fertilization). Compared to HN, grain yieldwas significantly reduced (35.6%) under LN level, as well as kernel number per ear, 1000-kernel weight, plant andear heights, and protein concentration. In the analysis over environments under each N level, genotypic variancewas significant and heritability was high for all traits. In the analyses across N levels and environments, genotypicvariance was significant for all traits and larger than the genotype × N and/or environment interaction variancecomponents except for protein concentration. In stability analyses across N levels, hybrids differed for their linearresponse to environments, and some showed dissimilar response under HN and LN levels. Our results indicatedthat breeding maize adapted to variable N levels is feasible with the Chinese germplasm available in the summerbreeding programs in North China Plain. Multi-environment tests are required to identify hybrids with high grainyield under variable N conditions, and examining yield stability separately under HN and LN would be useful.