Abstract:

Nitrogen is a large necessary element in maize development, and the nitrogen use efficiency is an important factor in deciding the cost of maize production, and also the plant height is served as an important index of the biomass. The purpose of this study was to locate the QTL for plant height in maize（Zea mays L.）in different developing stages under N-input (N+) and N-stress (N－) conditions. The unconditional and conditional QTLs for plant height were detected using F_2:3 population derived from an elite maize cultivar Nongda 108 (Huang C × Xu 178). The results showed that N-stress had more influence to plant height in the parent Huang C than in Xu 178, and there was no significant difference in the average of plant height for the F_2:3 families between the two nitrogen treatments, but the ranges of variation were different. The QTLs for plant height at different stages were detected with the composite interval mapping method and a molecular linkage map including 199 SSR markers. Under N- treatment, 1, 1, 2, and 2 QTLs were detected for plant height at elongation stage, small bell stage, large bell stage and grain filling stage, respectively. The total contribution of the detected QTLs could explain 8.42%, 13.86%, 24.33%, and 22.66% of phenotypic variation. Under N+ treatment, there were 1, 1, 2, and 4 QTLs for plant height in the four different stages above, accounting for 8.10%, 12.92%, 21.30%, and 44.41% of total phenotypic variation respectively. One and five QTLs for plant height were detected from elongation to bell stage and from large bell to grain filling stage under N- treatment, while 1, 4 QTLs were detected under N+ treatment, the total contributions of the detected QTLs were 9.14% and 50.98% as well as 13.33% and 44.47%, respectively. The inbred line Xu178 was less sensitive to low N stress than Huang C for plant height and was an inbred with high nitrogen use efficiency under low N condition. The 12 conditional and unconditional QTLs for plant height mainly located on chromosomes 1, 4, 5, and 9, four of them are different from those reported by predecessors in gene locations. About all of the conditional and unconditional QTLs detected appeared to be of dominant and partially dominant effects on plant height with explained the phenotype variation nearly ranging from 8% to 16%. Some QTLs such as qPH4b, qPH1c, and qPH7 only expressed in specific stages, that is the spatial temporal expression characteristics during the formation of plant height, which may be related with high N use efficiency.

Key words: Maize, Nitrogen, Plant height, Developing stage, QTL analysis