| In order to study the effects of soil salt content on the growth of rapeseed,a pot experiment was carried out during 2020～2021 and 202～2022 growing seasons,using hybrid rapeseed Qinyou 10 and the conventional variety Zheyou 50(Brassica napus L)as test materials,and three salinity levels(0,1.5,3.0 NaCl g kg-1 soil,referred to as S0,S1,S2)were set by adding sodium chloride to the soil.The plants were sampled to measure biomass accumulation,carbon and nitrogen content,photosynthetic rate,physiological index,seed yield and quality at the seedling,flowering and maturity stages.The main results are as follows:1.The effects of soil salt content on seed yield,oil content and protein content at the maturity stage reached a significant level.With the increase of soil salt content,the seed yield and oil content of rapeseed at the maturity stage were decreased significantly,while the protein content was increased significantly.Compared with control treatment,the seed yield of Qinyou 10 under 1.5‰and 3‰ salt content averagely decreased by 42.12%and 60.35%during two growing seasons,respectively,and Zheyou 50 by 40.12%and 56.69%,respectively.2.The biomass accumulation in various organs at the seedling,flowering,and mature stages decreased significantly with the increase of soil salt content.At the seedling stage,the biomass accumulation of leaf dramatically decreased among all organs,and the leaf in Qinyou 10 and Zheyou 50 under 3‰ salt content decreased by 52.49%and 53.40%as compared with control treatment,respectively.At the flowering stage,with the increase of soil salt content,biomass accumulation of all organs decreased significantly,and the reduction in stem was largest,followed by leaf,and root was the least.At the maturity stage,soil salt content also had a greater effect on biomass accumulation in stem,pod,and seed.Compared with control treatment,the biomass accumulation of stem and pod of Qinyou 10 under 1.5‰ salt content decreased by 32.03%and 40.61%,respectively.The reduction under 3‰ salt content was 45.39%and 56.51%,respectively.Compared with control treatment,the biomass accumulation of stem and pod of Zheyou 50 under 1.5‰ salt content decreased by 31.39%and 38.38%,respectively;the reduction under 3‰ salt content was 43.87%and 56.22%,respectively.3.The biomass partitioning in root and leaf were varied from 9.44%～12.22%and 87.78%～90.56%at the seedling stage,respectively.As the soil salt content increased,the biomass partitioning in root increased significantly,while the leaf decreased.The biomass partitioning in root,stem and leaf were varied from 12.30%～15.27%,53.49%～58.05%and 29.65%～31.24%at the flowering stage,respectively.With the increase of soil salt content,the biomass partitioning in root and leaf increased significantly,while the stem reduced.At the maturity stage,the biomass partitioning in root was the least,stem was the largest.With the increase of soil salt content,the biomass partitioning in root and stem increased significantly,while the pod and seed decreased.4.At the flowering stage,the C content in various organs were about 40%.At the maturity stage,the C content of seed was the highest,and the C content of root,stem and horn pod was about 40%.Salt stress significantly inhibited the C accumulation in various organs at the flowering and maturity stage.At the flowering stage,the reduction of C accumulation in stem was the largest,while that in root was the least.At the maturity stage,the C accumulation in seed was the highest,while it was strongly affected by salt stress.The C accumulation of Qinyou 10 and Zheyou 50 in seed decreased by 43.34%and 41.36%under 1.5‰ salt content,and by 61.63%and 60.94%under 3‰ salt content,respectively.5.The N content in root and stem varied from 1.18%～1.39%and 1.65%～2.05%at the flowering stage,respectively.The N content in root,stem and pod was less than 1%,and the N content in seed was the largest at the maturity stage.The N content of rapeseed improved at the flowering and maturity stage under salt stress.However,salt stress significantly inhibited N accumulation at the flowering and maturity stage.For example,at the flowering stage,as compared with control treatment,under 1.5‰ salt content,the N accumulation in Qinyou 10 and Zheyou 50 decreased by 10.96%for root,26.81%for stem,and 22.13%for leaf,and under 1.5‰ salt content by 30.35%for root,47.87%for stem,and 43.16%for leaf,respectively.The average N accumulation under different salt contents in root,stem,pod and seed at the maturity stage was 16.06 mg/plant,69.22 mg/plant,43.49 mg/plant and 259.44 mg/plant,respectively.The N accumulation at the maturity stage was also inhibited by salt stress.Especially,the decrement in both root and stem was similar(about 10%under 1.5‰ salt content and about 17%under 3‰ salt content.The N accumulation in pod and seed responded strongly to salt stress,with average decreasing by 38.35%and 36.19%for Qinyou 10 and Zheyou 50 under 1.5‰ salt content,and by 56.68%and 55.92%under 3‰ salt content,respectively.At the flowering stage,the C/N ratio in root was the largest,followed by stem,and the leaf was the least.At the maturity stage,the C/N ratio in root and stem was similar(about 65),and the seed was the least.As the soil salt content increased,the C/N ratio of all organs decreased significantly at both flowering and maturity stage.6.With the increasing soil salt content,the photosynthetic rate decreased significantly,while the activity of SOD and CAT and the content of soluble protein and soluble sugar increased significantly at both seedling and flowering stage.The increment in activity of SOD was more than that in CAT.The activity of SOD and CAT was increased by 34.80%and 20.74%in 1.5‰salt content,and 60.34%and 31.85%in 3‰ salt content,respectively.Regarding the osmolytes,the changing range of soluble protein was greater than that of soluble sugar.For instance,as compared with control treatment,under 3‰ salt content,the content of soluble protein and soluble sugar increased by 16.17%and 13.57%,respectively. |
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