| The field experiment was conducted in Shenmu, the ecological research farm of Institute of Soil and Water conservation, Chinese Academy of Science and Ministry of Water Resources, which were in the north of Loess Plateau with about 437.4mm precipitation each year. Study the canopy characteristics, root to shoot, distribution of assimilation and yield, nutrition, coefficient of water utilization of spring corn in different film (no plastic film-mulching and plastic film-mulching of all growth stage), different nitrogen fertilizer application (no nitrogen application and nitrogen application 90kg/hm2), different supplemental irrigation (80mm and 120mm). The main results showed as follows:1.The dynamic variation of canopy characteristics is different with plastic film-mulching, nitrogen fertilizer application and supplying water(1) The field observation showed that: the germination of plastic film-mulching was earlier than no plastic film-mulching, about 10d, so shortening the growth period 17d. The filling stage and spike differentiation of plastic film-mulching corn is ahead of time, which is beneficial to yield.(2) The growth of height could be divided into 3 stages: slowly increasing period, rapidly growth period and stable period. The height increased slowly before 10 leaves, but there is no significant boundary of slowly increasing period and rapidly growth period in plastic film-mulching corn.There is a significant effect of film-mulching on height before stable period. Nitrogen application can increase height significantly in the middle-end period. With the plastic film-mulching and heavy irrigation, the effect of nitrogen application on height is more significant. The inter-effect of film and nitrogen application on height showed in the middle growth period, and the stable stage is ahead of time with heavy irrigation.(3) Results showed: the variation of green leaf areas can be divided into 3stage: increase rapidly, stay high and decrease slowly. There is the single summit variation in the growth period. Leaf areas increased slowly from 5.12(4 leafs for no film, 6 leafs for film) to 6.6(8 leafs for no film, 10 leafs for film). The leaf areas of no film were the most in 7.12, and of film in 7.6. Both begin decreased after getting a climax, but the former changed gently and the later rapidly; both decreased rapidly after filling stage.The time of leaf areas getting the climax is different with nitrogen application in the different planting modes. The effect of nitrogen application on leaf areas is different with growth period, planting modes and irrigation. Before 7.6, effect of nitrogen application on leaf areas was slight, after that heavily, the filling stage decreased. From the average of all growth period, leaf areas of nitrogen application increased about 4484.2cm/m~2 than no nitrogen application. Effect of irrigation on leaf areas was relation with nitrogen application and film. In no film planting, heavy irrigation made the leaf areas decreased slowly after getting the highest, whether no nitrogen application or nitrogen application; but for film planting, it decreased rapidly with no nitrogen application, the contrast to nitrogen application. The difference of leaf areas between heavy and low irrigation is main in the middle-end period. The inter-effect of film and nitrogen application on leaf areas is significant.(4) The variation of SPAD changed with low-high-low in the middle-end growth period, which can reflect the relatively content of chlorophyll. The SPAD increased gradually and get the climax from 7.20 to 8.21, after decreased gradually.The film planting affect the SPAD, and the intent was relation to nitrogen application. With no nitrogen application, film planting decreased the SPAD significantly from 7.20 to 8.21, but there is no significant difference between them with nitrogen application. From the average, the SPAD of nitrogen application is higher than no nitrogen application, about 10.58. Effect of irrigation on SPAD is different with planting modes and fertilizer application.2. Spring corn dry matters accumulation in different organic was comprehensive embody in canopy character change with difference of plastic sheet-mulching-PSM, Nitrogen fertilizer and supplementary water.(1) Dry matter of root system accumulation rule follows Logistic equation-S curve basically, that was, seeding stage increase slowly, middle stage increase rectilinearly, last stage increase steady. With growth stage advance, root system biomass increase, it reach maximum in earing stage-irrigation initial stage, but descended after that. PSM affect root system biomass significantly in different growth stage, but in different direction, in the growth prophase PSM treatment biomass was greater than control(C) in the growth prophase, but it was contrary in the growth anaphase, PSM treatment biomass was greater than C slightly as a whole: biomass increase 5.28g/m~2(6.4%) after PSM. PSM affect root system biomass was different base on whether nitrogen fertilizer use and the quantity of irrigation: PSM maximal biomass is lower than C without nitrogen fertilizer. Nitrogen fertilizer affect root system biomass different or significantly different in different growth stage. Nitrogen fertilizer that affect root system biomass is single in different growth stage, it was different from PSM, that nitrogen fertilizer treatment s biomass was greater than no nitrogen fertilizer treatment.In the whole growth stage, biomass was 78.2g/m~2 with no nitrogen fertilizer, but is 12.6g/m~2 with nitrogen fertilizer. Irrigation treatment that affecting root system biomass was mainly in middle stage and last stage, compared with low irrigation, biomass over-ground increase 8.6g/m~2 with high irrigation in the whole growth stage.(2) Corn biomass over-ground accumulation rule follows Logistic equation-S curve basically. That was, seeding stage increase slowly, middle stage increase rectilinearly, last stage increase steady. Nitrogen fertilizer, PSM and irrigation affect biomass over-ground accumulation significantly different in the whole growth stage. PSM treatment biomass over-ground is greater than C all along, PSM was 930.5g/m~2, Cis 762.1g/m~2, it increased 168.4g/m~2 after PSM. PSM that affect biomass over-ground base on nitrogen fertilizer use or not and different of irrigation water, it was more effective when nitrogen fertilizer was use if is PSM treatment, nitrogen fertilizer treatments biomass over-ground was greater than no nitrogen fertilizer all along. Biomass over-ground increase216.0g/m~2 with nitrogen fertilizer in the whole growth stage. Nitrogen fertilizer an irrigation have a alternating effect on biomass over-ground in filling stage. Irrigation treatment affect biomass over-ground was mainly in middle and last stage. Corn whole biomass accumulation rule was similar with biomass over-ground.(3) The ratio of root to shoot was digressive in the whole growth stage, it descend quickly in the growth prophase, in middle stage it descend slowly, but steady in last stage. the change degree of the ratio of root to shoot of is greater with normal cultivation. It was reach maximum at seeding stage, it showed that root system grew quickly in the prophase, but over-land part grew quickly in the middle stage. PSM affect the ratio of root to shoot significantly different in the growth stages. From average figure of two different planting models in growth stages, the ratio of root to shoot was 0.26 with normal cultivation, it was 0.15 with PSM, it decreases 0.11(42.3%) with PSM. From the change rule of the ratio of root to shoot in the whole growth stage, it changed steady with PSM, but it changed much in the prophase with normal cultivation. Nitrogen fertilizer that affects the ratio of root to shoot was mainly in filling stage, it descended significantly after nitrogen fertilizer use. There was no obvious effect in the growth prophase and in the middle stage with nitrogen fertilizer; irrigation that affects the ratio of root to shoot was no rule pattern in different growth stages.(4) PSM, nitrogen fertilizer and irrigation that affect corn dry matter allotment in different organ was much complex. PSM, nitrogen fertilizer and irrigation affect leaf biomass significantly different in the whole growth stages. From seeding stage to earing stage, PSM increase leaf biomass significantly different, but it was not obvious in the growth anaphase. leaf biomass was greater with nitrogen fertilizer than no nitrogen fertilizer all along. Irrigation treatment affect leaf biomass was mainly in middle stage and last stage. PSM treatment shoot grow early, and it come into maturing stage ahead 15 days. Shoot biomass increase 16.1g/m~2 with PSM in the whole growth stages. Nitrogen fertilizer can increase shoot biomass significantly different in the different stages. Shoot biomass increase 57.7(21.6%) after nitrogen fertilizer. Compared with big quantity water treatment, low quantity water treatments that affect shoot biomass was greater all along. Male flower growth rule in the ear biomass reach maximum steady for 15 days, biomass descends after that. Nitrogen fertilizer increased, PSM can increase female flower biomass significantly different at booting stage. Nitrogen and PSM decrease female flower biomass significantly different. The quantity of irrigation has no significantly effect on female flower biomass in the growth stages. Normal cultivation and PSM, spike biomass reach maximum at the same time. PSM increased spike biomass significantly different. PSM impact was more obvious with nitrogen fertilizer. PSM and nitrogen fertilizer had a significantly internal effect on spike biomass. Nitrogen fertilizer also increase spike different. Average biomass with nitrogen fertilizer was 716.6g/m~2, but it was 498.6g/m~2 with no nitrogen fertilizer, it increased 218.0g/m~2 with nitrogen fertilizer. Compared with PSM and nitrogen fertilizer, the quantity of irrigation is not obvious.3.PSM, nitrogen fertilizer and complement irrigation have internal effect different on corn yield, nitrogen and water use efficiency(1) It is considered from grain yield, grain yield increase 14.8% when the quantity of irrigation increase 80mm. PSM that increase yield was 31.6%. It increase 40.1%when nitrogen fertilizer use was 90ke/ha. PSM and nitrogen fertilizer increase corn yield, and it was 81.5%. Nitrogen fertilizer, PSM, complement irrigation and other measures can increase corn yield, which is 109.1%. it was considered from PSM, nitrogen fertilizer and irrigation, PSM increase 1564.4kg/hm2(24.1%) averagely, nitrogen fertilizer increase 2688.1kg/hm~2 (45.4%) averagely, high quantity of irrigation increase 1151.7kg/hm2( 17.2%) averagely. Different of experimental factors affect nitrogen absorbing content and phosphoresces was accord with yield and biomass over-land accumulation in harvest stage.(2) PSM and increasing irrigation can increase nitrogen fertilizer use efficiency significantly different, and there was positive internal effect between them. In different stage of irrigation, water use efficiency was increasingly, but decrease steady after. In the seeding stage, corn grow slowly, so water use efficiency of per day is slow too. The average of WUE per day was 0.13kg/hm~2.mm.d with normal cultivation. But it was 3.3kg/hm~2.mm.d with PSM. PSM is higher than normal cultivation on WUE of per day, and it was 2.5 times. In nutrition increasing quickly stage, the average of WUE per day was 1.38kg/hm~2.mm.d with normal cultivation and PSM was 1.92kg/hm~2.mm.d. in generating stage, the average of WUE per day was basic same, WUE descend quickly without no nitrogen fertilizer and PSM, the average decrease from 1.87kg/hm~2.mm.d to 0.78kg/hm2.mm.d, The average of WUE per day decrease two thirds.(3) It was considered from grain yield, NUE and WUE, in the experiment that the optimum planting model was "PSM+160mm water upply+90kg/hm2 nitrogen fertilizer use. Grain yield reach 10118.7kg/hm~2 in this model, and NUE is 82.3%, NPE was 58.7kg/kg.n, corn WUE reach 44.0kg/mm.hm~2 (biomass) and 19.8kg/mm.hm~2 (grain), and this index is greatest in different treatments.
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