| In order to inquire into the high yield physiology of new maize hybrids , search the cultivation measures for high-yield and high-benefit, and then provide necessary theory and technique guidance for extension and application of new hybrids, the morphology and physiology of yield formation under different fertility and planting density conditions and the resistance to drought and senescence and the combined cultivation measures for Shendan 10, Dongdan7 and Yingdan11 were studied. The results were as follows:1.The significant positive correlation between dry matter accumulation and fertilizer level of N, P and K was found in each hybrid. There was a significant positive correlation between dry matter accumulation and grain yield at ten days after elongating in Shendan10, after filling in Dongdan7 and after elongating in Yingdan11. If the level of fertilizer was improved, the dry matter yield was improved by increasing the biggest rate of dry matter accumulation in Shendan10 and in Dongdan7, or reducing the decline rate of dry matter accumulation in Yingdanl 1. A peak of dry matter distributing into ear during the filling stage was observed in different of hybrid populations with different levels of fertilizer and planting density, The more dry matter was stored in stems before tilling, and the more it was diverted into ear at filling stage, the grain yield was higher.2.There was a significant difference of LAI between hybrids and the order of LAI among hybrids was ShendanlO > Dongdan7 > Yingdan11. LAI was affected mainly by planting density. A significant positive correlation between LAI and density at every development stage before filling was found in each hybrid There was a very significant correlation between LAI and yield in Shendan10 afterfilling and in YIngdanll before flourishing filling, but the same correlation was not significant in Dongdan7 at every development stage. In high density of populations of ShendanlO and Dongdan7 (67,500plants ? hm2), and in medium-density of populations of Yingdanl 1 (52,5OOplants ? hm2), the LAI was bigger at high-fertilizer level than at medium-fertilizer level. Under high-density condition, high-fertility had an effect on postponing the decline of LAI, especially in ShendanlO;the LAI was 6 or so at mature stage. The changes in chlorophyll contents in three hybrids at different stages were similar. The chlorophyll content per leaf area was the highest at flowering stage, and then decreased slowly The order of chlorophyll content among 3 hybrids was ShendanlO > Dongdan7 > Yingdanl 1, and the high-fertility of populations > low-fertility of populations in the same hybrid3.The correlation was significant between filling rate and yield at beginning and ending of filling stage in ShendanlO, at medium ending of filling stage in Dongdan7 and at medium filling stage in Yingdanl 1. At the same time the filling rates in medium-fertility were higher than low-fertility in three hybrids. If the filling rates were raised and the filling time were prolonged, the grain yield would be increased further more.4.There were different in plant types among three hybrids. The results were that the order of the angles between stem and leaf above the ear was ShendanlO > Yingdanl 1 > Dpngdan7, the leaf area per plant was ShendanlO > Dongdan7 > Yingdanl 1 and the plant height was ShendanlO > Dongdan7~ Yingdanl 1. Under high-fertility condition, the angle between stem and leaf below the ear decreased significantly and the leaf orientation value increased significantly in ShendanlO and Dongdan7. Under high-density population, the angle between stem and leaf under the ear was decreased significantly or almost significantly, and the leaf orientation value increased significantly in three hybrids The interaction of fertility and density resulted into the increasing of the leaf orientation value above ear significantly. With the increase of planting density, the leaf orientation value above the ear increased in three hybrids and this relationship could be indicated by linear equation.5.The light distribution in maize canopy was different with hybrid characteristics. In the same hybrid it was influenced by plant height, density and leaf orientation value. The changes of transmittance on different layer of canopyat different fertility and density conditions obeyed the law of Beer-Lambert and could be expressed as l/l^ae'^'.6.The difference of drought and senescence resistance in three hybrids was obvious. The result of system identification was that the drought resistant hybrid ShendanlO was higher than that of Yingdanll, Dongdan7 was sensitive to drought. The senescence resistant hybrid ShendanlO showed a higher chl. content, larger green leaf area and stronger function of leaves than those in others. It would be benefit to improve drought and senescence resistance by reinforcing N fertilizer, fitting P and K fertilizer and decreasing planting density.7.The mathematic model of four factors and yield was established based on the design of four factors (N, P, K and density) quadric orthogonal regression rotation combinations. With computer simulation and optimization, the optimal agricultural measure combinations were obtained.If the rainfall was deficient, the combinations of N, P, K and planting density were as follows:ShendanlO: N 190—260 kg ? hm"2, P,O5 113 — 140 kg ? hm:, K2O 152 — 2.08 kg ? hm2, Planting density 52500—57500 plants ? hnV2. Dongdan7: N 266—308 kg ? hm2;P,O5 120—150 kg ? hm2, K2O 90—120kg ? hm"2 Planting density 58300—63000 plants ? hm"2. ' Yingdanll: N 295 — 320 kg ? hm2, P2O5 139—173kg ? hm2, K2O 170 —190kg ? hm2, Planting density 53900—58200 plants ? hm"2. If the rainfall was sufficient, however, the combinations of N, P, K and planting density were as follows:ShendanlO: N 263.4—280.5 kg ? hm"2, P 75.5—87.2 kg ? hm"2, K 92.4-137.4kg ? hm"2, Planting density 52800—53600 plants ? hm"2. Dongdan7: N 168.8—229.1 kg ? hm"2, P 77.0—144.0 kg ? hm2, K 92.4-137.4kg ? hm"2, Planting density 51500 — 51700 plants ? hm"2. Yingdanll: N 191.4—206.3 kg ? hm2, P 41.0 — 90.6 kg ? hm2, K 115.1 — 135.0kg ? hnV2, Planting density 50500 —523 10 plants ? hm 2.
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