| To some extent,the agronomic landscapes which are mainly designed by farmer practices determines the intensity of the climate impacts on the crop production.Therefore,it’s of great significance to investigate how the agricultural landscape pattern and regulation affects crop climate suitability.In the present study,different types of agronomic landscapes at farm and hillslope scales were presented to test their roles inmitigating negative climate effects and achieving stable high yield under current and future climate scenarios.Combining the field measured data,meteorological data and remote sensing image data,two main crops(Maize and Soybean)in the northestern China were selected to systematically study the following topics:(1)differences of the conopy microclimate and crop yields among these different landscape patterns at farm scale;(2)how landscape positons and ridge directions at hillslope scale affect the productivity of cropping systems in different climate yearsThe results of this study are as follows:(1)The impacts of different planting row spacing on Maize systems’ microclimate and yield at farm scale.(1)Canopy temperature and humidity before warming: There was distinct difference in the canopy temperature among these maize plant-row spacing patterns,but the difference was not significant.The canopy temperature decreased with increase in row spacing and decrease in plant spacing except the treatment of 70cm×29cm,and the changes in the humidity were opposite.Generally,the canopy temperature is the lowest and humidity is the largest for the treatment of 65 cm x 31 cm.(2)Canopy temperature and humidity after warming: The canopy temperature increased significantly under different planting landscape pattern.The canopy relative humidity decreased for the treatments of 55 cm x 36 cm and 65 cm x 31 cm patterns There is significant differences(p < 0.01)in canopy temperature and humidity between warming and the corresponding no-warming treatments.After warming,there was no significant differences in canopy temperature and humidity under the difference of different patterns.The treatment of 55 cm x 36 cm had the highest canopy temperature and lowest humidity.(3)Indicators of crop yield before warming: SPAD value,hundred kernel weight and yield varied with different patterns,but there were not significant differences at 0.05 significant level.The treatments of 55 cm x 36 cm got higher and stable yield.(4)Indicators of crop yield after warming: SPAD value,hundred kernel weight and yield decrease after warming.Similiarly,there were not significant differences(p < 0.05)in these indicators among these treatments.The treatments of 70 cm x 24 cm got high and stable yield and it was the optimal patternIn addition,our results indicated thatthe treatment of 65 cm x 31 cm pattern could obtain higher yield under the four landscape patterns.in high temperature and pests serious years.(2)The impacts of different planting row spacing on Soybean systems’ microclimate and yield at farm scale.(1)Canopy temperature and humidity before warming: There was distinct disfference in the canopy temperature among these soybean plant-row spacing patterns,but the difference was not significant.The canopy temperature increased with increase in row spacing and decrease in plant spacing.In a certain of palnt-row spacing,the humidity decreased with the increasing of row spacing and the decreasing of plant spacing.(2)Canopy temperature and humidity after warming: Warming made the soybean canopy temperature and humidity significantly changed(p < 0.01).The effect of 55 cm x 6.1cm canopy temperature and humidity was the greasteat,and the 70 cm x 4.8 cm pattern was the minimum by warming.Under the configuration of 65 cm × 5.2cm,the canopy temperature was the highest and the humidity was the lowest.(3)Indicators of crop yield before warming: Soybean SPAD value,hundred kernel weight and yield varied with different patterns,but there were not significant differences at 0.05 significant level.The treatments of 55 cm x 6.1cm and 60cm×5.6cm got higher and stable yield.(4)Indicators of crop yield after warming: SPAD value,100-seed weight and yield were more complex,but not significant.And the yield showed a rising trend.The 70 cm x 4.8 cm configuration had the highest yield.(3)The roel of agronomic landscape pattern fo r adapting cropping systemsat hillslope scale.In the years of 2014,2015 and 2017,the area of cropland at the slope scale expandedand the increase rate for maize was higher than that of soybean.Askew ridge was the main type at the whole slope,accounting for 51% of the cropland area.In the summitslope positions,the area of maize increased in the form of askew ridge,while the area of soybean decreased.The area of maize in 2015 was higher than that of soybean in the backslope positions.The area of soybean in 2014 and 2017 was higher than that of the maize.This showed that the maize and soybean intercropped year by year.In the footslope positions,maize and soybean were distributed in the form of slices.The maize area showed an increasing trend with years,and most of croplands were transformed into dip ridge.The area of soybean decreased with years.(4)Cropland productivity under agronomic landscape patternsat hillslope scale.Overall,the crop productivity at hillslope scale followed as the summitslope positions > the backslope positions > the footslope positions.In the footslope position,the productivity of maize in the askew was higher in 2014 and 2017.The maize productivity was higher in strike ridge in 2015.In the backslope position,in 2014 and 2017,the highest productivity of maize occurred in the form of strike ridge.In 2015,it was planted in askew ridge;In the summitslope position,when the cultivation of maize was dip ridge in 2014,the productivity was the largest.And the productivity in the form of the askew ridge was higher in 2015 and 2017.The ridge in 2015 got the highest productivity.In 2014 and 2017,soybean productivity in the form of strike ridge was higher.Based on the above results,the optimal agronomic landscape patterns for cropping system to adaptclimate change were presented in this study.Under current climate conditions,the configuration of 55 cm × 36 cm is suitable for maize on the land parcel scale.With the rising temperature,configuration pattern of 70cm×24cmis better.As for soybean,the planting pattern of 55cm~60cm is suitableunder both the present and future climate change.For the distribution of crops on the slope scale,The agronomic landscape pattern of Maize on the hillslope scale varied in different climate condition years.On the premise of reasonable ratio of maize and soybean planting,maize planting area should be increased in the summitslope positions,soybean planting area could be increased in drought or wet year in the backslope position,soybean planting area should be increased in footslope position.The ridge direction selection for different crops in different slope positions are as follows: in the footslope position,in normal years,mazie should be planted in the strike ridge,soybean could be planted by dip ridge.Maize could be planted in askew ridge in drought and humid years,and soybean is planted by striken ridge.In the backslope position,the askew ridge of maize in the normal year was more productive,and the soybean was planted by dip ridge.In the wet and dry years,the maize could be planted by strike ridge planting and the soybean was planted in the strike ridge.In the summitslope position,in normal years,maize can obtain greater productivity in the form of askew ridge,soybean could be planted by dip ridge.In drought year,maize should be planted by askew ridge and soybean should be planted by strike ridge.In humid year,maize should be planted by dip ridge,soybean planted in the form of askew ridge can obtain the highest productivity. |
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