| The lack of agricultural water resources has become an important problem in the world;and it becomes increasingly serious with the increasing of grain demand and population.Dry semi-humid areas is an important grain production region in China,but the lack of irrigation water has become the important limit factors for development of agriculture in the region;therefore,developing the water-saving agriculture will play a important role in promoting sustainable development of agriculture in there.Ridge-furrow with plastic film mulching(RFPFM),as a prospective rainwater harvesting system,has been widely adopted in rain-fed arid and semi-arid regions in northern China.However,it has less research about whether RFPFM can be applied to wheat–maize double cropping systems(winter wheat-summer maize)in dry semi-humid areas.Three cultivation practices(rainfed flat planting: CK,RFPFM and well-irrigated planting: WI)in combination with two nitrogen(N)rates(high N: 225 kg N ha-1 per crop season;low N: 75 kg N ha-1 per crop season)and two winter wheat-summer maize cultivars(Xinong979-Zhengnong9 and Xiaoyan22-Zhengdan958)were conducted to systematic research the effects of RFPFM on winter wheat-summer maize yield,morphology and physiological characteristics,saving-water and increasing-efficiency in dry semi-humid areas.The study not only provides theoretical and practical support for application and promotion of RFPFM in dry semi-humid areas,but expands and enriches theory of RFPFM.The main results of this research are as follows:(1)Compared with CK,RFPFM practice hastened winter wheat and summer maize seeding emergence by 2 days,delayed flowering of winter wheat by 1-3 days and length the winter wheat growth period by 2-4 days;RFPFM practice hastened 4 days in silking of summer maize,and no difference in the summer maize growth period.Plant height of winter wheat and summer maize were significantly higher under RFPFM practice than the CK practice,and RFPFM were lower than WI;the same trends to leaf area index(LAI)of middle and late period of winter wheat and jointing and grain filling stage of summer maize.Compared with CK,aboveground biomass of the winter wheat and summer maize under RFPFM practice can significantly increased by 55.7% and 37.4%;the aboveground biomass of winter wheat under RFPFM reached 76% of WI practice and summer maize was no significant difference with WI.RFPFM practice,in comparison with CK,increased the intercepted radiation and total radiation use efficiency(RUE)of winter wheat by 42.5% and 43.4%,lower than WI with no significant difference.In addition,the intercepted radiation and RUE of summer maize under RFPFM practice were significantly increased by 9.4% and 26.7% in comparison with CK,respectively;compared with WI,RFPFM practice significantly reduced the intercepted radiation and no significant difference about RUE.The RUE of winter wheat-summer maize under RFPFM practice was significantly increased 22.4% compared with CK and no significant difference with WI practice.(2)In winter wheat growing seasons,the mean grain-filling rate of superior grains in early stage showed: WI>RFPFM>CK;the flag leaf areas of anthesis stage under WI and RFPFM practices were significantly increased by 119.4% and 25.1% in comparison with CK practice,respectively,and RFPFM practice was significantly lower than WI practice;the chlorophyll relative content(SPAD value)of wheat flag leaves under WI practice was higher than RFPFM and CK practice in the late of grain-filling stage.The correlation analysis showed that,due to different effects on initial filling power and active grain-filling date,WI,CK and RFPFM had different effects on grain weight.In summer maize growing seasons,final weight of a kernel,100 grain weight achieving the maximal grain-filling rate(Wmax)and mean grain filling rate(Gmean)showed: WI>RFPFM>CK.In early stage of grain filling,the days of RFPFM and WI were lower than CK;the mean grain filling rate and increased grain weight showed: WI>RFPFM>CK.In middle and late stage of grain filling,increased grain weight also showed: WI>RFPFM>CK.The decrease of SPAD value of ear leaf under CK practice was more than RFPFM and WI practice;RFPFM and WI have no significant difference.The correlation analysis showed that,due to RFPFM practice could improve A? Wmax and Gmean,and increase grain weight of summer maize;grain weight between RFPFM and WI are not always significant difference.(3)In 20 days after flowering of winter wheat,the plant height and LAI of RFPFM practice was significantly higher than CK practice and lower than WI practice,and RFPFM increased LAI by 99.2% in comparison with CK;The light transmittance showed: CK>RFPFM>WI,which had significant differences.Compared with the WI practice,the plant weight per unit length under RFPFM and CK increased significantly.The length and diameter of the second basal internode under RFPFM practice increased significantly in comparison with CK practice,but RFPFM practice was lower than WI practice.The dry weight per unit length and wall thickness of the second basal internode of RFPFM practice was 20.9% and 4.2% higher than WI practice,respectively.The RFPFM increased breaking resistance by 23.9% in comparison with WI and bending moment by 25.4% in comparison with CK.The lodging index showed: CK>RFPFM>WI,which had significant differences.The correlation analysis showed that,due to effects on plant height,spike number,LAI,yield,aboveground biomass,breaking resistance,bending moment and length of the second basal internode,lodging tolerance of RFPFM practice was significantly higher than WI practice,and lower than CK practice.In milk stage of summer maize,the plant height,ear height,gravity centre height,plant weight,LAI of RFPFM practice was significantly higher than CK practice,but lower than WI practice;the similar trends to length,fresh weight,dry weight and stalk rind penetration strength of the third basal internode;light transmittance and bending resistance showed: CK>RFPFM>WI;lodging resistance index also showed: CK>RFPFM>WI,which had significant differences.The correlation analysis showed that,due to effects on plant height,ear height,gravity centre height,LAI,yield,bending resistance and length of the third basal internode,lodging resistance of summer maize under RFPFM practice was significantly higher than WI practice,and lower than CK practice.(4)Compared with CK,RFPFM significantly increased the yield of winter wheat,reached 76% of WI practice,which accompanied by higher spike number;while RFPFM practice increased water use efficiency(WUE)by 53.7% and 46.3% compared with CK and WI practices.The maize yield of RFPFM was similar to WI practice,and increased the number of kernels per ear,1000–kernel weight and grain yield compared to the CK practice;the RFPFM practice increased WUE by 29.2% and 70.5%,compared to the CK and WI practices,respectively.The RFPFM practice significantly increased winter wheat-summer maize yield,WUE and N fertilizer use efficiency;RFPFM practice increased winter wheat-summer maize yield by 37.1% in comparison with CK practice and reached 89.5% of WI practice;in addition,RFPFM practice increased WUE of winter wheat-summer maize by 38.9% and 61.0%,compared to the CK and WI practices,respectively;the N fertilizer productivity and N uptake efficiency of winter wheat-summer maize under RFPFM were significantly increased by 40.7% and 44.2%,respectively,compared with CK,and no significant differences with WI;the winter wheat-summer maize net income per hectare in a year under RFPFM practice increased by 5000-11000 Yuan in comparison to the CK practice and was no significant difference with WI;thus,RFPFM practice could save the water,increase grain yield,WUE and N fertilizer use efficiency.In conclusion,RFPFM can become better water-saving and high-efficiency cultivation pattern under wheat–maize double cropping systems in dry semi-humid areas. |
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