The Selection Of Lodging Indicators And Mapping QTL For Lodging In Brassica Napus L.

Lodging causes loss of seed yield and decrease of seed quality, especially for mechanized harvesting. Exploring suitable indictors of lodging will facilitate rapeseed breeding against lodging. To achieve this goal, two sets of related experiments were performed in 2010 and 2011. In the first set of experiment, a panel of 68 rapeseed accessions, including hybrids and inbred lines were used to explore suitable agrionomic traits as indictors of lodging. In the second experiment, these indictors of lodging were mapped in a DH population derived from a Germany winter rapeseed (Express) and a Chinese semi-winter rapeseed (SWU 7). The main results are as follows:1. Selection of lodging indicatorsAmong agronomic traits, plant height and Resistant Pressure Per Plant significantly and highly corrected with lodging index with correlation coefficient of 0.74 and-0.55, respectively. Path analysis showed that plant height was the greatest contributor to lodging while RPPP was the greatest to lodging-resistance. The studies have shown that plant height, RPPP two lodging related traits constitute a significant interaction between themslves. The results showed that low plant height, high RPPP can reduce lodging in rapeseed.2. Mapping QTL for lodging resistance indicators:1) Analysis of variance and correlation analysis showed significance between years and between the lodging related traits.2) We used 446 polymorphic SSR markers for genetic linkage analysis. Using Map 1, a total of 292 markers was identified in the genetic linkage map which represent 65.5% of the total number of markers on the map. The map contains 19 linkage groups with a total length of 1187.5 cM. The largest number of makers was in the 5th linkage groups, containing 28 markers, but the 10th and 17th linkage groups, respectively, had only 4 markers.3) CIM analysis detected nine QTLs that affect plant height. Five QTLs were detected in 2010, in which four makers were detected by single-marker analysis and four QTLs in 2011, in which there were three makers detected by the single marker analysis. CIM analysis detected eight RPPP QTLs of which SWUC512, SWUC210 were detected in the two years.