Genetic variation in yield of five hybrids of sweet corn grown under poultry manure and nitrogen fertilizers and the presence of the nitrate reductase gene (Nia2)

Concern about nitrate (NO3−) accumulation in plants and its hazard to human and animal health has led to the investigation of the genetic variation in its accumulation in plants.Genetic variation in the productivity and nitrate content of sweet corn hybrids (Zea mays L.) when produced under five treatment combinations of chemical nitrogen fertilizer and poultry manure was investigated. In addition, the presence of the nitrate reductase gene (Nia2) in hybrids of sweet corn was investigated by PCR analysis. The chlorophyll content of leaves was higher with chemical fertilizer and the mixture of chemical fertilizer and chicken manure compared with chicken manure only. The highest grain yield was recorded in the hybrid Amera grown with chicken manure or the mixture of nitrate fertilizer and poultry manure. Moreover, gene-specific primer pairs for amplification of nitrate reductase revealed the presence of the nitrate reductase gene (Nia2) in hybrid Merit, which had the lowest grain nitrate content. Moreover, Merit only had one extra band (900 bp) indicating the Nia2 gene was controlled by co-dominant alleles. However, the presence of nitrate reductase gene (Nia2) alone did not explain nitrate content differences among corn hybrids. The work presented in this paper showed that PCR assays represent a sensitive tool for screening of sweet corn breeding material for the Nia2 gene although the presence of this gene does not alone explain nitrate content. Key words: Genetic variation, Low nitrate concentrations, sweet corn, nitrate reductase gene (Nia2), PCR