A large replum-valve joint area is associated with increased resistance to pod shattering in rapeseed

The structure of the replum was studied in 64 rapeseed lines and in an F2 population derived from a cross between a high pod shattering resistance line, zy72360, and a susceptible line, R1. The dimensions of the replum close to the pedicel in lines with high silique shattering resistance index (SSRI) were greater than those with low SSRI. The replum-valve joint area index (RJAI) was used to investigate the relationship between the replum size and pod shattering. In the 64 accessions, RJAI displayed wide variation (0.50–4.12 mm2), with a variance coefficient of 45.4 %. There were highly significant positive correlations between SSRI and RJAI, with a correlation coefficient of 0.6140. Analysis of RJAI in 276 F2 individuals further validated the positive correlations between SSRI and RJAI. These results revealed that replum structure was highly associated with pod shattering, and that a thick replum structure could produce high pod shatter resistance. The replum-valve joint area offers a good method to screen high resistance materials beneficial for breeding.