A huge amount of precipitation and higher water table during rapeseed growing season in Yangtze River regions grown with rice and rapeseed rotation system and heavy soil result in frequent waterlogging occurrence. A pot experiment was performed at four growth stages with three waterlogging time treatments which were followed by normal water administration. Two rapeseed lines with different levels of waterlogging tolerance were used to investigate the effects of the sustainable waterlogging time on rapeseed growth and yield. The treatments were waterlogging of 10, 20 and 30 days at seedling and budding stages and 10, 15 and 20 days at flowering and maturity stages. The results showed that (1) the sustainable waterlogging time affected the development of roots, the growth of up-ground part of plant and yield, which was significantly different between two lines; (2) waterlogging at seedling stage led to the decrease of chlorophyll content in leaves, and the increase of malondialdehyde and proline contents; (3) sensitivity to waterlogging judged by yield in different developmental stages of rapeseed ranked in the order of budding stage, flowering stage, seedling stage, podding and maturity stages; (4) the research on effects of sustainable waterlogging time on yield can provide a basis for estimating the influence of continuous rainfall on rapeseed production.
The naturally drought-prone climate of the Tibetan Plateau has produced highly drought-resistant Brassica juncea. The objective of the present study was to examine improvement in drought resistance in B. napus by distant hybridisation between B. juncea and B. napus. Distant hybridisation was performed to generate F1 hybrids, which were open-pollinated by a set of breeding lines of B. napus. Continuous self-crossing was then performed to produce the F2–F6 generations, and 74 lines of new-type Brassica napus with stable fertility and morphological phenotypes were selected. The drought resistance of the 74 lines was evaluated during the germination stage by simulating drought stress at 15% PEG-6000, and a wide range of genetic variation in drought resistance was scored. Cytological identification of four lines chosen from strongly, intermediate and weakly drought-resistant clusters demonstrated that their chromosomes had gradually stabilised to B. napus (2n = 38) after advanced self-crossing. A drought-resistant line (line 290) and a drought-susceptible line (line 299) were selected to determine the physiological response to drought stress at the seedling stage. The results showed that proline, soluble protein and malondialdehyde contents of the drought-resistant line were always lower than those of the drought-susceptible line and other common rapeseed variety under drought stress and rewatering conditions. This indicates that the drought-resistant line may have a better reactive oxygen species scavenging system with a less extreme reaction to drought stress. Additionally, the results revealed that the genetic diversity of B. napus under drought resistance was broadened by distant hybridisation, which could encourage breeders to utilise the germplasm resources of B. juncea in the Tibetan Plateau to achieve the goal of drought resistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.