| In this study,Ningza 1818(Brassica napus L.)was chosen as experiment material,and the effects of transplanting date and transplanting density on agronomic characters of plant,dry matter accumulation of different organs,grain yield and quality in mature period were investigated.Also,a comparative experiment was conducted on mechanical transplanting and conventional artificial transplanting.We hope to find out the optimal transplanting density and transplanting period that suitable for the blanket transplanting rapeseed,laying the foundation for large-scale mechanical transplanting the blanket-type seeding.The main results are as follows:1.Effects of transplanting period on growth and yield of blanket transplanting rapeseed.In this experiment,the highest yield'appeared on October 25,reaching 3810.09 kg/hm2,which was 432.84 kg/hm2,291.18 kg/hm2,211.59 kg/hm2,234.28 kg/hm2 and 368.25 kg/hm2 higher than that of October 15,October 20,October 30,November 4 and November 9,respectively,with the increase of 12.82%,8.27%,5.88%,6.55%and 10.70%respectively.The differences were significant.From the different planting patterns,the yield of direct-seeding rapeseed on October 15 was 107.25 kg/hm2 higher than that of blanket transplanting rapeseed,with the increase of 3.2%,and the difference was significant.The yield of blanket transplanting rapeseed of other treatments were all higher than that of the direct-seeding rapeseed,and the differences were significant.The path analysis of yield components and yield showed that under different transplanting periods,the yield of blanket transplanting rapeseed was mainly improved by increasing the number of pods and seeds per pod,while under different sowing dates,the direct-seeding rapeseed improved the yield by increasing the number of seeds per pod.The dry matter weight of the organs at maturity,dry matter accumulation after flowering and yield were analyzed,and the result showed that for both of the blanket transplanting and direct-seeding rapeseed,the dry matter accumulation after flowering of was closely related to the yield.The result of regression analysis of different transplanting and direct-seeding periods and yields showed that the latest sowing date of direct-seeding rapeseed was on October 16,otherwise its yield will be lower than the same period of blanket transplanting rapeseed.Regression analysis results showed that the highest yield appeared on October 27,and the best transplanting period was between October 23 and October 31,and the suitable transplanting period was from October 18 to November 5,To achieve a high level of 3000 kg/hm2 above,the latest transplanting period was November 13.But the result of regression analysis of different transplanting and direct-seeding periods and economic benefit showed that the economic benefits of transplanting rapeseed and direct-seeding rapeseed were the same on October 21,October 21 when transplanting rapeseed and rapeseed economic benefits of the same,before October 21,the profit of direct-seeding rapeseed was higher than that of blanket transplanting rapeseed,then the opposite.To sum up,under the conditions allowed by the stubs,before October 21,the direct-seeding rapeseed was more effective,after which the mechanical transplanting of blanket-type rapeseed should be used.The suitable transplanting period for the mechanical transplanting of blanket-type rapeseed was from October 21 to November 5,and the latest transplanting date for high-yielding cultivation was November 13.2.Effects of density on growth and yield of blanket transplanting rapeseed.Among the seven treatments,when the density was 225 thousand plants/hm2,the yield was highest,reaching 3699.94 kg/hm2,which was 1-323.9 kg/hm2,840.36 kg/hm2,292.24 kg/hm2,218.63 kg/hM2,314.74 kg/hm2 and 528.04 kg/hm2 higher than that of the density treatments of 90 thousand plants/hm2,135 thousand plants/hm2,180 thousand plants/hm2,270 tthousand plants/hm2,315 thousand plants/hm2 and 360 thousand plants/hm2,respectively,with the increase of 55,7%,29.4%,8.6%,6.3%,9.3%and 16.6%,respectively.The differences were significant.Regression analysis results showed a quadratic curve relationship between the yield and the density.According to the regression equation,we can figure out that the most suitable density was 255.7 thousand plants/hm2,and the suitable density range was between 227.5 thousand plants and 283.9 thousand plants per hectare.The path analysis of yield components and yield showed that the reason for improving the yield under the condition of density was to improve the 1000-grain weight on the basis of keeping the suitable number of pods.The main reason was that with the increase of density,the number of pods can be greatly increased,and pod as rapeseed's main photosynthetic organ in the late stage of growth had a suitable range,and too many or few was not good for the improvement of seed yield.The dry matter weight of the organs at maturity and the dry matter accumulation after flowering and yield were analyzed.Result showed that the dry matter accumulation after flowering and the dry matter weight of the pods' peel were closely related to yield,which suggested that increasing the dry matter accumulation and the dry matter weight of the pods' peel could improve the yield,and promoting the growth of root and stem played an important role in improving the yield.The result of the comparison trial of one plant per hole and two plants per hole showed that the number of pods per plant,the number of population pods and the number of seeds per pod of one plant per hole treatment were higher than those of two plants per hole treatment,and the 1000-seed weight was lower than that of two plants per hole treatment,but the difference was not significant.It can be seen that one plant or two plants per hole had little effect on the yield.In practice,adopting one plant or two plants per hole could be based on the density of the blanket-type seeding,the soil condition and the mechanical adaptability and so on.3.Effects of mechanical transplanting and artificial transplanting on growth and yield of rapeseed.The results showed that the seed yield of the artificial transplanting rapeseed was 3697.35 kg/hm2,which was 440.33 kg/hm2 lower than that of mechanical transplanting rapeseed,with the decrease of 10.6%,and the difference was significant.The main reason was that the number of pods of artificial transplanting rapeseed was 11.32×106 pods/hm2 lower than that of mechanical transplanting rapeseed,with the decrease of 19.7%,and the difference was significant,but the difference of their seeds per pod and the 1000-grain weight were not significant.It can be seen that the number of pods of mechanical transplanting rapeseed had a appropriate range and high yield;But the number of pods was not enough,which was the main reason that affect the yield of the artificial transplanting rapeseed.The number of population pods is determined by the number of pods per plant and density.Therefore,to increase the number of population pods is to improve the number of pods per plant and the density.The result of this study showed that the number of pods per plant of artificial transplanting rapeseed was 392.6 grains,which was 93.6 grains higher than that of mechanical transplanting rapeseed,with the increase of 31.3%,and it was more difficult to further increase the number of pods per plant.However,it was easy for mechanical transplanting rapeseed to increase the density,and its density was 63.4%higher than that of the conventional artificial transplanting rapeseed.Which suggested that the difference between mechanical transplanting and artificial transplanting was mainly caused by different density.Due to artificial transplanting rapeseed requires many workers and plenty of time,further to increase the density is impossible.The transplanting density of large-scale production is usually much lower than the density of this test,which therefore limits the further increase in the yield of artificial transplanting rapeseed.4.Effects of different planting patterns on grain quality of rapeseed.With the postponement of the transplanting date,the oil content and erucic acid of seed were gradually decreased,while the content of protein and glucosinolate gradually increased;Of all the date treatments,the oil content of blanket transplanting rapeseed was higher than that of direct-seeding rapeseed,while the content of protein,glucosinolate and erucic acid were the opposite.The result of density trial showed that increasing the density could improve the oil content of the seed and reduce the content of protein,glucosinolate and erucic acid,which had little effect on the oil content.But the content of protein,glucosinolate and erucic acid in low-density seed was significantly higher than that of high density.There was no significant difference in oil content,protein,glucosinolate content and erucic acid content between seeds under one plant per hole and two plants per hole treatments.Mechanical transplanting or artificial transplanting had little effect on the quality of rapeseed. |
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