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Root and Canopy Aging Characteristics of Super High-yield Spring Maize and the Reaction Mechanism to Density

Author: WangHaiYan
Tutor: GaoJuLin
School: Inner Mongolia Agricultural University
Course: Crop Cultivation and Farming System
Keywords: Super high-yeild Spring maize Root and canopy aging Planting density
CLC: S513
Type: Master's thesis
Year: 2011
Downloads: 119
Quote: 1
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Abstract


Densification is the basic condition for achieving super high-yield spring maize, but it aggravated the aging process of individual maize, different ear varieties showed different response to densification. The test explored super high-yield spring maize aging characters including the root and canopy. In the field trials, super high-yield spring maize varieties (Xundan 20, high stalk with large ear; Neidan 314, medium stalk with medium ear) were grown under different planting densities(75000-120000 plants/hm2). The results were as follows:1. Under different planting densities, the bottom leaves aged earlier than the top and ear leaves, the ear leaves was the slowest at flowering and milking stage; The root aging presented moving down spatially in different depths of the soil layers, the aging speed of root and canopy increased with increased planting density. Anti-aging membership function value of root and canopy indicated that the planting density effected plant senescence mainly through POD activity of overground part and root activity of underground part.2. Photosynthetic character and fluorescent properties of single leaf, nitrogen accumulation and aging enzyme activity of root and canopy of spring maize cultivars decreased with increased planting density, while LAI and lipid peroxidation productions of root and canopy increased at flowering and milking stage.3. The reaction of grain weight of different grain position of high stalk with large ear showed that inferior grains were higher than superior grains and superior grains were higher than medium grains. But medium stalk with medium ear showed that superior grains were higher than medium grains and medium grains were higher than inferior grains. The maximum filling rate, the average filling rate were highly significant positive correlated with grain weight. But the filling duration, time of maximum filling rate were significant negatively correlated with grain weight. The time of maximum filling rate of inferior grains delayed 7.33d and 5.11d in average than superior and medium grains of high stalk with large ear, and delayed 5.95d and 3.69d than superior and medium grains of medium stalk with medium ear.4. Leaf nitrogen content has very significant positive correlation relationship with SPAD value and Pn at silking and filling stage, but has weak correlation or irrelevance at mature stage; Grain nitrogen content was related with SPAD value and Pn at these three stages, the degree of correlation with SPAD value is greater than Pn; Nitrogen harvest index of the two cultivars were maximum at 105000 plants/hm2.5. The increasing of yield is significance with the increased planting density gradient of the two cultivars. The significance of difference among yield and its components of medium stalk with medium ear were less than high stalk with large ear, and high stalk with large ear is more likely to develop "density effect".In summary, Super high-yield spring maize varieties had higher yield under high planting density, it was mainly related to high LAI, population dry matter accumulation, grain filling duration and root activity at flowering and milking stage in the growth process, Therefore, enlarging LAI, adding population dry matter accumulation, increasing root activity and protective enzyme activity, enlarging total storage capacity at flowering and milking stage would be beneficial to obtain higher yield under appropriate planting density.

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