Research Of Photosynthetic Characteristics And Determination Of Fruit Quality Of Korla Fragrant Pear Under Different Planting Density

The experimental materials of this study were the20years layered-shaped of Korla Pear trees, and theplanting density respectively is3m×5m,4m×5m,5m×6m. Mainly analyzes in different areas and differentperiods the dynamic change rule and discrepancy of three density canopy in light, temperature, humidityand air CO2concentration. And the differences of these environmental factors on photosyntheticcharacteristics, chlorophyⅡ fluorescence characteristics, chlorophyⅡ content, specific leaf weight andfruit quality, then find out the relationship between them. The results prove that:1. The differences of environmental factors main show is light and temperature:5m×6m﹥4m×5m﹥3m×5m, peripheral﹥interior; air humidity:4m×5m﹥3m×5m﹥5m×6m, interior﹥peripheral; air CO2concentration: no significant difference between different density, peripheral﹥interior. There are largeseason differences of these environmental factors, annual variation of light intensity, temperature andhumidity showed a single peak curve, the peak appeared in June or July; air CO2concentration showed“W” shape change from May to September.2. Pn and Gs of three densities main show is4m×5m﹥5m×6m﹥3m×5m, different positions within thecanopy main show is peripheral﹥interior; Tr:5m×6m﹥4m×5m﹥3m×5m, peripheral﹥interior; nosignificant differences in Ci between each density, interior﹥peripheral. Seasonal variation of Pn, Gs, Cidodsn’t rule between each density. The seasonal variation of Tr was a single peak curve, the peak valueappeared in July. The photosynthetic capacity is4m×5m﹥5m×6m﹥3m×5m, peripheral﹥interior.3. The light saturation point of different density:5m×6m﹥4m×5m﹥3m×5m, different parts of thecanopy: peripheral﹥interior; apparent quantum yield: no significant difference between different density,different parts of the canopy: interior﹥peripheral. Sparse planting trees and outside leaves had strongerphotosynthetic capacity, close density and bore leaves by increasing the apparent quantum yield tostrengthen the ability of use weak light. The CO2response curve is similar to photoresponse curve. Sparseplanting and outside leaves had higher CO2saturation point.4. Chlorophyll content representing as in different density:3m×5m﹥4m×5m﹥5m×6m, but did notreach significant level; different parts of the canopy: interior﹥peripheral, and significant difference, leavesby increasing chlorophyll content to make full use of light energy under weak light. Specific leaf weight isopposite, leaf with adequate illumination, the leaf quality is higher.5. Maximum PS II light energy conversion efficiency and PS II light conversion potential all appear to3m×5m﹥4m×5m﹥5m×6m, interior﹥peripheral. The density of5m×6m susceptible to light inhibition;and the density of3m×5m is closed, lead to the potential activity of PS II high but can not be fully released,so the density of4m×5m more reasonable.6. Ample light thin planting and peripheral fruit than low light close planting and bore fruit fruit weightis bigger, the ratio of sugar and acid is higher, the fruit hardness smaller; but light enough fruit have low Vccontent and more stone cell content. Through principal component analysis, the comprehensive qualityranking4m×5m peripheral＞5m×6m peripheral＞5m×6m interior＞3m×5m peripheral＞4m×5m interior＞3m×5m interior.Density of4m×5m groves in photosynthetic capacity, light energy conversion efficiency and fruit qualityhave more advantages than the other two density, therefore, suggest4m×5m of the promotion in theproduction of fragrant pear planting density.