| Intercropping is an effective measure to improve land use and water use efficiency.However,intercropping is also severely restricted by water shortage of resource type.It is of great significance to study the response of soil water distribution,water consumption law and crop growth to improve water use efficiency of intercropping system under different irrigation amount.Based on the growth and development characteristics,yield advantage characteristics,water consumption characteristics and water use efficiency index of maize soybean intercropping system,the dynamic distribution of underground water,the movement law of soil water and the response of canopy physiological and ecological characteristics to soil water were studied under different irrigation amount,The dynamic water consumption law and growth mechanism of compound population were explored.In this study,four kinds of planting methods,intercropping(T2),intercropping root spacing(T1),monocropping maize(T3)and monocropping soybean(T4),were set up under three irrigation quantities W1(75%FC),W2(85%FC)and W3(100%FC).(1)The field soil water content under intercropping was affected by irrigation amount and growth period.With the development of growth process,the soil water content before each irrigation decreased gradually.The soil water content of intercropping treatment was 20.11%,19.94 mm,18.75%and 17.81%respectively before four times of irrigation,and the decrease value of soil water increased with the increase of irrigation water.Under the condition of intercropping,the water consumption of maize was higher than that of soybean,that is,soybean growth contributed a certain amount of soil water to maize.(2)Irrigation amount affected the potential soil water movement of maize soybean intercropping,and the total change trend of potential soil water movement in the whole growth period was from small to large.At Maize Jointing Stage(soybean branching stage),the potential water transport of soil water under W2 and W3 irrigation was the largest in the whole growth period,which were 13.50 mm and 69.90 mm,respectively.From seedling stage to jointing stage,the water content of 0-100cm soybean zone was 2.41%-4.14%higher than that of corn zone;At tasseling stage,the water content of soybean was 2.33%?3.65%higher than that of maize;At grain filling stage,the water content in soybean zone was 1.05%-1.23%higher than that in maize zone.Maize intercropping with soybean had complementary effect on water requirement.(3)The plant height and leaf area of intercropping maize and monoculture maize increased by 6.83%on average with the increase of irrigation amount.The plant height and stem diameter of intercropping soybean decreased with the increase of irrigation amount.The effect of irrigation on leaf area of intercropping soybean was not significant.The average plant height of intercropping maize was lower than that of monoculture,and that of intercropping soybean was higher than that of monoculture soybean.Under W2 and W3 irrigation,the stem diameter of intercropping maize increased by 2.93%?7.91%compared with monoculture maize,and there was no significant difference between W2 and W3 irrigation;The leaf area index(LAI)of intercropping maize increased by 6.35%?15.32%,and that of intercropping soybean decreased significantly.The average SPAD value of intercropping maize increased by 3.54%?6.89%compared with monoculture maize(P<0.05).(4)The dry matter accumulation of intercropping maize increased with the increase of irrigation amount,and the dry matter quality of intercropping maize increased by 28.21%compared with monoculture maize.There was no significant difference between W2 and W3irrigation amount treatments;The dry matter accumulation of intercropping soybean decreased with the increase of irrigation amount,and the dry matter quality of intercropping soybean was 24.65%lower than that of monoculture soybean(P<0.05).The harvest index of intercropping maize was 8.63%higher than that of monoculture,but there was no significant difference between W2 and W3.The harvest index of intercropping soybean and monocropping soybean decreased gradually with the increase of water amount after W2irrigation.(5)The land equivalent ratio(LER)of maize soybean intercropping ranged from 1.02 to1.22.The results showed that intercropping had advantages over monoculture under three irrigation rates,but there was no significant difference between W2 and W3 irrigation rates;The competitiveness(AMS)of Maize to soybean under different irrigation amount was greater than 0.The competitiveness of Maize to soybean under W3 irrigation amount was increased by 9.97%and 16.27%respectively compared with W1 and W2 treatments.There was a quadratic significant correlation between the weight grain yield and competitiveness of intercropping population,and the suitable range of competitiveness was 0.80-0.90;The competition ratio(CR)of maize/soybean in the intercropping system was greater than 1 under different irrigation amount,and maize was the dominant crop in the intercropping system.(6)The lowest value of soil water storage(soil water storage before irrigation)of maize?soybean intercropping decreased gradually with the growth period.The decreasing value of soil water storage from large to small was W1>W2>W3,with significant difference among treatments.The period from jointing stage to tasseling stage of Maize under three irrigation amounts was the maximum period of soil water storage consumption.The soil water consumption of intercropping increased with the increase of irrigation water.The total water consumption of maize intercropping soybean under W1,W2 and W3 irrigation was 382.25mm,476.58 mm and 554.36 mm,respectively.(7)The yield of intercropping maize increased by 23.56?33.64%compared with monoculture.The yield of intercropping maize increased with the increase of irrigation amount,but there was no significant difference when the irrigation amount increased from W2 to W3;The yield of soybean decreased significantly with the increase of irrigation amount.The population yield under W2 and W3 irrigation was 25.36%?33.69%higher than that under W1 irrigation.There was no significant difference between W2 and W3 irrigation,but WUE under W2 irrigation was significantly higher than that under W3 irrigation.The water equivalent ratio of W3 and W2 was 17.35%higher than that of W1,and there was no significant difference between W3 and W2.Under W2 and W3 irrigation amount,intercropping significantly improved soil water availability and water use efficiency of intercropping population compared with monoculture.The weighted water use efficiency of W2 and W3 irrigation amount treatments reached 22.30 kg·hm-2·mm-1 and 18.26 kg·hm-2·mm-1,respectively. |
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