Mapping Quantitative Traits Loci For The Lodging Resistance Of Culm In Rice

Lodging is a common problem in rice production and it can reduce yield, rice quality and mechanical harvesting efficiency, thus rice production with lodging resistance varieties has been a main aspect of high-yield and excellent-qualities rice breeding. In the paper, plant resistant press per plant was measured in ninety-eight backcross inbred lines (BILs) derived from a intersubspecific backcross of Nipponbare (Japonica)/Kasalath(Indica)//Nipponbare at the 18th day after heading. At the same time, the biomass per plant (BPP), plant height (PH), number of internode, length of internode, number of vascular bundles and culm thickness (CT) were also measured. The relationships between lodging index (LI) and plant height, culm thickness, biomass per plant etc. in rice were analyzed and quantitative trait locus analysis were conducted. The main results were as follows:1 .Plant height, culm thickness and biomass per plant were correlated to the lodging index at the 1% level of significance. By using multiple regression analysis approach with flanking markers, four QTL (qLI-1, qLI-3, qLI-8 and qLI-12) were identified to be significant for the lodging index. These four individual QTL explained 18%, 10%, 14% and 10% of the individual phenotypic variation, respectively. Among them, qLI-1,qLI-8, and qLI-12, whose additive effect come from Kasalath, represented the adding lodging index. Whereas, qLI-3, which exhibited improving lodging resistance and didn't exist in the genetic linkage with such traits as plant height, culm thickness and biomass per plant, reduced the lodging index with the negative effect denoted by the high-culm cultivar, Kasalath. The QTL of qLI-3 might be used in rice breeding for lodging resistance with molecular assistant.2.Analysis of correlation coefficients showed positive correlation between resistance press per culm, culm thickness and the number both of the large and small vascular bundle. Thus these traits might be selected index for lodging resistance in rice breeding. Two QTL for the number of large vascular bundle were identified, which located on chromosome 3 and 6, and explained the phenotypic variation 11.01% and 9.99%, respectively. Their individual genetic effects might increase the number of vascular bundle by 0.458 and 0.460, respectively. Three QTL for the number of small vascular bundle were identified, which located respectively chromosome 6, 7 and 11, explained the total phenotypic variation by 12.48%, 8.52% and 9.16%, respectively. Their individual genetic effects might increase the number of vascular bundle by 0.683, 0.629,...