Genetic basis of nutritional content of stover in maize under low nitrogen conditions

The effect of two different nitrogen treatments on five traits associated with yield and nutrient composition of stover were evaluated using a set of 213 F2:3 families derived from two elite inbred lines Huang-C and Xu178. Evaluation of the phenotypes expressed under the two nitrogen conditions showed that low nitrogen conditions could increase acid detergent fiber (ADF) and neutral detergent fiber (NDF), and decreased crude protein content (CP), crude fat content (CF), and stover yield (SY), thereby negatively affecting the digestibility and quality of silage maize. Twenty-eight quantitative trait loci (QTL) were identified affecting the five measured traits under two nitrogen conditions, including four for ADF, five for NDF, five for CP, four for CF, and three for SY. Several QTL associated with ADF or NDF were detected under same nitrogen conditions, and were localized to the same chromosomal regions, especially the QTL qADF6 and qNDF6, qADF10 and qNDF10, were only detected under low nitrogen condition. These results suggested that ADF and NDF perhaps were controlled by several common genes, and that the nutritional content of stover may be influenced by additional genetic mechanisms when grown under conditions of low nitrogen.