| Affected by global warming,rapeseed cultivation in my country has shown a trend of"moving north and expanding westward",and the planting area of winter rapeseed in the north has been increasing.This makes it more and more feasible to rotate winter rape and summer corn in some winter wheat-summer corn rotation areas.Different from the climatic conditions of the traditional winter rapeseed cultivation area,the north,especially the northwest,is dry and rainless all year round.The ditch rainwater harvesting and mulching film has a significant effect on warming and moisture preservation,which can effectively alleviate the drought problem.Therefore,for the vast arid,semi-arid and semi-humid areas in the north,research on the sowing date and density of winter rape-summer maize based on the ridge and furrow rain harvesting mode is of great significance for improving the utilization efficiency of light and heat resources,saving irrigation water,enriching the structure of northern agricultural production,and increasing agricultural production benefits.The effects of different planting methods,sowing dates and densities on the soil hydrothermal environment,physiological growth and yield during the growth period of winter rape and summer corn were studied.Use yield and water use efficiency as evaluation indicators.The purpose is to obtain a winter rape-summer maize rotation production model suitable for Guanzhong area,and provide a theoretical basis for the cultivation of winter rape and summer corn in this area and the further study of the crop’s response to water,fertilizer,gas,and heat.The main conclusions are as follows:(1)Ridge film mulching and furrow planting technology can significantly improve the soil water and heat conditions during the growth period of winter rape and summer corn,and promote the increase of crop growth and yield.Film mulching improves the soil water content and water use efficiency during the growth period of crops,while reducing water consumption,and significantly increases the soil temperature of the 0-25cm depth soil layer in the early growth period.The plant height,stem thickness,leaf area index,chlorophyll content,above-ground dry matter and root dry quality of mulched crops increased.Compared with plain cropping,the number of branches,siliques and thousand-grain weight of winter rapeseed at mature stage increased,yield(sown on September 22)increased by39.1%to 55.9%,and water use efficiency increased by 51.2%to 64.7%.The number of grains per row,ear thickness,ear length and 100-kernel weight of summer corn increased,yield increased by 39.4%-81.1%,and water use efficiency increased by 39.4%-82.0%.(2)The suitable planting density of winter rapeseed cultivated by ridge film mulching and furrow planting is lower than that of flat planting.Increasing planting density will intensify competition among individual winter rapeseeds,increase water consumption,decrease soil temperature,decrease plant height,stem thickness,root dry mass,silique number,and 1000-seed weight,increase taproot length,population leaf area index,and mass of dry matter on the ground.Film-covered winter rape grows better,accumulates more dry matter,and competition is more intense.This study shows that the suitable planting density for winter rapeseed planting with film mulching is 100,000 plants/hm~2(yield is4658.7kg/hm~2);the suitable planting density for winter rapeseed planting on flat planting is150,000 plants/hm~2(yield is 3252.3kg/hm~2).(3)Normal sowing date after summer corn harvest,ridge film mulching and furrow planting techniques can be used to resee winter rapeseed after the summer corn is harvested,which can ensure the safe overwintering of late sowing winter rape and increase the yield of winter rape.The postponement of the sowing date limits the dry matter accumulation at the seedling stage of winter rape,reduces the number of branches and siliques per plant in the mature stage,reduces the thousand-grain weight,and reduces yield.Film mulching increased the soil water content in the greening period of winter rapeseed after overwintering,and with the delay of the sowing date,the soil water content of the winter rapeseed after overwintering increased significantly.The higher soil moisture content ensures the rapid growth of winter rapeseed after overwintering,and reduces the yield loss caused by the delayed sowing date.When the sowing date was postponed from B1(September 22)to B3(October 12),the overwintering rate of P1(flat planting)was only30%,and the yield dropped by 66.9%;while P2(ridge film mulching and furrow planting)could survive the winter safely,and the yield dropped by 28.05%.(4)Under the winter rape-summer maize rotation model,the growth status and yield of the film-mulched summer maize were better than the winter wheat-summer maize rotation,and the suitable planting density was increased accordingly.The increase in planting density limits the growth of individual summer corn,reduces soil water content and soil temperature during the growth period of summer corn,and increases water consumption.The stem thickness and leaf area per plant decreased during the filling stage,but the plant height,leaf area index and the mass of dry matter above the ground increased.The number of rows,ear length,ear thickness and 100-kernel weight decreased during the mature period.The sowing date is advanced,the effective accumulated temperature during the growth period and the daily average temperature during the filling period of summer corn increase,the filling period is prolonged,and the 100-kernel weight under the same density treatment increases significantly.B1(sown on May 28)achieved the highest yield at 100,000plants/hm~2,with a yield of 12522.5 kg/hm~2;B2(sown on June 15)achieved the highest yield at 75,000 plants/hm~2,with a yield of 11492.0 kg/hm~2.(5)Based on the ridge film mulching and furrow planting technology,the rotation of winter rape-summer maize has improved soil water and heat conditions,and significantly improved water use efficiency and yield.This study shows that in the Guanzhong area,ridge film mulching and furrow planting techniques were used to sow winter rapeseed in late September,and winter rapeseed can be harvested in late May.After that,summer corn is sown,which can be harvested in mid-to-late September.The density of winter rape and summer maize is controlled at 100,000 plants/hm~2,and the highest yield can be obtained. |
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