Genetic Analysis On The Main Agronomic Traits Of Elite Reeding Lines In Brassica Napus L.

Oilseed rape is the major source of edible oil and plant protein, and it plays an important role inagricultur production our country. Hybrid rape accounted for more than60%of rapeseed planting areain China. Breeding companies devote great efforts on the development of hybrid rapeseed varieties.Research institutions are interested in elucidating the genetic mechanisms of rapeseed heterosis. In thisstudy, yield related traits, pod related traits and plant type related traits were analyzed based on datacollected from a6×5incomplete diallel design at two environments. By using a genetic model includingadditive and dominance effect and their interaction with environments, important agronomic traits wereanalyzed for genetic effects and correlation in oilseed rape. The results are as following:1. The largest contribution rate of phenotype and additive variance to pod SRI was from pod wallweight, the second was from pod length. It was obvious that genetic variation existed among backbonebreeding lines and their crosses for pod SRI. Pod shattering resistance was likely controlled by fewgenes with mainly additive effects, and dominant effects were much less important, whereas theenvironments played only minor role for pod SRI. The pod trait with the highest contribution rate ofadditive effect to pod SRI varied depending on different parental lines, indicating the parental linesespecially those with relatively high pod SRI possess different genetic background for the resistance topod shatter. Thus it is possible to pyramiding those pod related traits which contributed significantly tothe additive effect of pod shatter resistance from different lines by multiple crosses and further improvethe pod shatter resistance of parental lines for hybrid breeding. There was no significant heterosis inmost of the crosses. The genetic variations of pod length,1000-seed weight, pod density and seeddiameter were mainly explained by additive effects, whereas those of pod wall weight and number ofseeds per pod were mainly affected by dominant effects. Among the11backbone breeding lines, ZS11Band R11were recommended for using as direct parental lines for making hybrid varieties with podsshattering resistance as maintainer and restorer of lines for Polima cytoplasmic male sterility system,respectively, due to their higher general combine ability on pod SRI and other yield component traits.2. The largest contribution rate of phenotype variance to yield per plant was from pods per plant,the second was from pods of main raceme. Dominant effects were the main genetic component for yieldper plant and pods per plant. These two traits were greatly influenced by environmental effect. Traitswith the highest contribution rate of dominant and environmental effects to yield per plant varieddepending on different combinations, indicating the crosses with relatively high yield possess differentgenetic background for the yield traits. Dominant effects were the major genetic component for pods ofmain raceme, seeds per pod and harvest index, additive effects were the mainly genetic component forpods per centimeter, primary branches and1000-seeds weight. Among the11elite breeding lines,1019B and R9were recommended for using as direct parental lines for making high yield hybridvarieties as maintainer and restorer of lines.3. Additive effects were the main genetic component for plant height, whereas environmentaleffects did not play any role. Branch height was mainly influenced by dominant effects, and environmental effects was important as well. Gravity height was major influenced by dominant effects,and was affected by additive effects. Dominant effects were the mainly genetic component for thicknessof rhizome, and environmental effects also reached significant level.