| Hebei Plain is the most serious agricultural production area of groundwater depletion in China.The contradiction between food production and high water consumption is increasingly prominent.At the same time,the warming and drying phenomenon caused by global warming is becoming more and more serious,and the rainfall is decreasing with the rise of temperature.It needs a lot of water resources to obtain high and stable yield by traditional double cropping.In order to alleviate the pressure of high water consumption,improve water use efficiency,explore new planting mode,and maintain high yield is very important.In order to provide theoretical basis for water-saving and agricultural production in Hebei Plain,the yield formation of wheat maize,annual water and heat resource utilization efficiency,economic benefits and environmental impact of two crops in one year,three crops in two years and one crop in one year under plastic film mulching and water-saving irrigation were compared and analyzed.The main results were as follows:In a rotation cycle,under the four planting modes,the total yield of W/M is the highest.Compared with W/M,the yield of W/M-M and M decreased by 6.2%?26.9%and 33.8%-47.5%respectively.Under the same cropping system,the increase of irrigation is beneficial to the increase of yield,and the advantage of plastic film mulch is higher than that of open field,especially in maize production.Rain-fed cultivation of winter wheat and spring maize is easy to reduce yield due to drought.During the vegetable stage,it suffered from drought,even if there is sufficient rainfall,the yield reduction caused by the decrease of grain number per ear and effective ear number can not be supplemented.Through the analysis of water consumption of wheat and corn in different planting systems.Adjustment of planting system,reduction of irrigation amount and increase of plastic film mulch can reduced irrigation water consumption.The decrease of wheat planting time between W/M-M and M,The total water consumption of rotation cycle was significantly lower than W/M.Under the same system,water-saving irrigation and plastic film mulching were carried out the water consumption of rotation cycle was reduce 18.9%?28.8%,18.1%?27.4%,5.0%?17.9%than conventional planting under W/M,W/M-M,M.And the water use efficiency was increased 8.8%?39.5%,14.7%?30.6%,2.8%?23.1%.Under the water-saving irrigation+plastic film mulch,winter wheat and spring maize only irrigate water once in their growth period,the water storage and water conservation capacity of mulching film can ensure enough water use in the critical growth period,to achieve the purpose of increasing production and saving water.In addition,the soil water storage was effectively conserved after maize harvest with plastic film mulching,which achieved the effect of "storing water in autumn and storing water in spring and to preserve soil moisture by plastic film mulching".The conventional planting fallow period of W/M is only a few days,the efficiency accumulated temperature of rotation period for 97.7%of the total accumulated temperature.The decrease of ripening system makes more time for the land to recuperate.The efficiency accumulated temperature of W/M-M and M accounted for 67.9%?72.4%and 41.8%?46.2%of the total accumulated temperature respectively.The growth period of wheat and maize was shortened by plastic film mulching and rain cultivation,especially in dry years.The growth period of wheat and spring maize was shortened by 9?14 days and 5?15 days respectively.For summer maize,the growth period was the same,but plastic film increased the filling length of summer maize and provided time for the increase of grain weight.The shortening of growth period reduced the accumulation of effective accumulated temperature in the growth period of winter wheat and spring maize,and increased the utilization efficiency of effective accumulated temperature.The effective accumulated temperature utilization rate of rainfed cultivation is lower than that of irrigation treatment due to the reduction of yield,while the water-saving irrigation+plastic film mulching promotes the of yield,increases the effective accumulated temperature utilization efficiency,and makes full use of the heat resources in rotation cycle.Sub-soil plastic film mulch promoted the leaf area index and dry matter accumulation of wheat and maize.The decline of leaf area index and dry matter accumulation after anthesis were related to supplementary irrigation.The increase of supplementary irrigation can slow down the decline of LAI,maintain high relative chlorophyll content,increase the photosynthetic characteristics of leaves,promote the accumulation of dry matter after anthesis.The transport of dry matter from vegetative organs to grains before anthesis was greatly affected by the drought at the silking stage.In dry years,mulching and rainfed in open film in during the growth period of wheat can promote the dry matter transfer from vegetative organs to grains.When maize is affected by drought during silking,the dry matter transfer from vegetative organs to grains is not conducive.According to analysis of Economic benefits,the economic income of mulching and conventional planting in W/M are higher than those of other treatments.Under the rainfed of open film,The decrease of wheat yield is the main reason for the decrease of cycle yield.The economic benefit of which is lower than W/M-M(except the rainfed with plastic film mulch),and the economic benefit of M is the lowest.Compared with W/M and M,the yield investment ratio of the same planting mode with W/M-M is the highest.According to the emergy analysis,the UEV of Conventional planting in W/M is the highest,and the environmental load potential rate produced of the saving irrigation+plastic film mulching is the highest,the emergy sustainability index of open field is higher than that of mulching,and the rainfed of open field with three crops of M is the highest.At the end of a rotation cycle,W/M had a higher impact on the environment an increase of 26.6%?27.2%and 53.4%?54.9%than W/M-M and M respectively.Among them,the effect on the environment of conventional planting in W/M is the highest.Comprehensive analysis shows that saving irrigation+plastic film mulching and rainfed(plastic film mulching and open film can reduce water consumption and increase water use efficiency in all planting systems.W/M and W/M-M have higher yield advantage and economic benefit.In the future,it is a trend to increase plastic film mulch and reduce irrigation to replace the conventional cultivation of W/M. |
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