| Increasing the production capacity of rapeseed in Jiangsu coastal areas is an important measure to support the development of Jiangsu rapeseed industry.Soil available phosphorus content in coastal areas is relatively low,therefore application of phosphorus fertilizer significantly increased yield.This study was conducted to investigate the effect of phosphorus fertilizer rate on Ningza 1838(Brassica napus L.)in saline soil in 2018～2019 and 2019～2020.Six levels of phosphorus fertilizer rate were arranged:0 kg hm-2,30 kg hm-2,60 kg hm-2,90 kg hm-2,120 kg hm-2,and 150 kg hm-2,respectively.Plant dry weight,photosynthetic parameters,phosphorus content,agronomic traits and seed quality were measured at seedling,beginning flowing and mature stage.Main results were as following:1.The yield increased significantly with increasing of phosphate fertilizer rate from 0 kg hm-2 to 120 kg hm-2.But there was no significant difference between 120 kg hm-2 and 150 kg hm-2.Therefore,the recommended rate of phosphorus fertilizer in this area is 120 kg hm-2.With increasing of phosphorus fertilizer amount,the oil content of seed in the two growing seasons presented a increasing trend.The change tendency of oil content with the increasing of phosphorus fertilizer rate was similar with the yield.2.with the increasing of phosphate fertilizer rate from 0 kg hm-2 to 120 kg hm-2,plant height and number of first branch at maturity stage increased,and the increasing extent of first branch number was relatively larger.The the number of pods per plant was also increased With the increasing of phosphate fertilizer rate,and the maximum number was increased by 56.40%as compared to the minimum one averaged over two growing seasons.Compared with the minimum of seed per pod,the maximum number was increased by 11.32%.The number of seeds per pod in the treatment of 0 and 30 kg hm-2 phosphorus fertilizer was below 17 seeds per pod,which was lower than these in the treatment of 90,120 and 150 kg hm-2 phosphorus fertilizer.The variation of 1000-seeds weight was relatively little.3.Leaf area index varied from 1.75 to 2.41 at seedling stage and 3.56 to 4.80 at beginning flowering stage respectively,which increased significantly with the increase of phosphorus fertilizer rate from 0 kg hm-2 to 120 kg hm-2;the net photosynthetic rate was ranged from 15.89 to 21.43 umol CO2·m-2·s-1 and 21.99 to 24.95 umol CO2·m-2·s-1 at seedling stage and beginning flowering stage respectively,and it was increased significantly with the increasing of phosphorus fertilizer rate from 0 kg hm-2 to 60 kg hm-2,there was no significant difference when phosphorus fertilizer rate was above 60 kg hm-24.The dry weight of the whole plant in 120 kg hm-2 was increased by 29.61%at the seedling stage,41.31%at beginning flowering stage and 55.25%at mature stage,respectively,compared with these in 0 kg hm-2.With the increasing of phosphorus fertilizer rate from 0 kg hm-2 to 120 kg hm-2,the dry matter partition in root was increased significantly,while the dry matter partition in shoot was decreased significantly at seedling stage.The dry matter partition in root in the treatment of 0 kg hm-2 at the beginning flowering stage was significantly lower than that in other treatments;the dry matter partition in branches in 0,30 and 60 kg hm-2 was significantly higher than these in other phosphate fertilizer rates,while the dry matter partition in leaves showed opposite trends With the increasing of phosphorus fertilizer rate,the dry matter partition in root and seed was increased,but the dry matter partition in stem and branch was decreased.The variation of dry matter partition in shell was relatively little among different treatments.5.Compared with dry matter accumulation,the increasing ranges of phosphorus accumulation amount in whole plant and different organs were larger as phosphate fertilizer rates increasing;phosphorus accumulation amount of whole plant increased by 63.27%,83.36%and 150.61%at the seedling,beginning flowering and mature stages respectively under 120 kg hm-2 level,compared with the treatment of no phosphorus application.The proportion of phosphorus distribution at seedling stage showed a trend of gradual increase with the amount of phosphorus fertilizer increasing in root and a trend of gradual decrease in over-ground part.at the beginning flowering stage,the distribution proportions of phosphorus in root and leaf with the treatments with no phosphate fertilizer and 30 kg hm-2 rate,were significantly lower than that of other rates,while the proportion in stem and branch were significantly higher than other treatments.At mature stage,the difference of phosphorus distribution proportions in root,stem and branch were relatively little among different treatments.The phosphorus distribution proportions in shell decreased with increasing of phosphate fertilizer rate from 0 kg hm-2 to 120 kg hm-2,while phosphorus distribution proportions in grain showed an increasing trend6.The phosphorus fertilizer utilization efficiency was ranged from 9.08 to 16.21 kg seed kg-1 P under different treatments,and it was decreased significantly with the increasing of phosphate application rate,with the most reduction(18.50%in 2018-2019,21.01%in 2019-2020)obsevered phosphorus fertilizer increasing from 120 to 150 kg hm-2. |
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