Soaking seeds with paclobutrazol enhances winter survival and yield of rapeseed in a rice-rapeseed relay cropping system

Abstract

<span class="fontstyle0">Rice-rapeseed relay cropping is an effective way to use winter fallow fields and increase<br />land use efficiency. However, the overlapping period of 10–15 days for rice-rapeseed<br />cultivation results in reduced winter survival and less yields. Therefore, in this study, we<br />investigated if the treatment of oil rape seeds with paclobutrazol (PAC) improves its winter<br />hardiness and yields by altering its crop morphology. First, a pot experiment was conducted to<br />determine the appropriate PAC concentration to soak seeds upon seedling growth and the<br />germination rate. Another pot trial was performed to check the responses of different rapeseed<br />cultivars to the proposed treatment. Rapeseed was cultivated in no-tillage rice fields at an<br />experimental site in Wuhan from 2009 to 2011. In the absence of PAC treatment, rapeseed sown<br />in pots and rice fields showed excessive elongation of the crown, which resulted in low yields<br />and yield-related traits at maturity. Soaking seeds in PAC improved seedling growth, seedling<br />survival and crown diameter, but decreased the crown length during winter. The most effective<br />concentration of PAC was 4 mg/L and higher concentrations significantly reduced seed<br />germination rates. Our results demonstrated that rapeseed sown in rice fields after the seeds had<br />been soaked with PAC improved seedling quality at the wintering stage and yield at maturity.</span>