The Effect Of Water Content In Soil On Photosynthetic Physiological Characteristics Of Pear And Fruit Quality

Drought is the most common, the greatest impact of climate disasters, as the global climate warming, drought and semi-arid regions to grow, the threat of drought on agriculture growing, soil moisture conditions restricting the growth of the region's major environmental fruit factors. Pears for the exploring different soil moisture conditions in the physiological and ecological characteristics of elements and mechanisms of change, and different soil moisture conditions on pear yield and quality to provide a theoretical basis for this article carried out under different soil moisture conditions of the physiological and ecological reaction of the pear. Experiment with'Cuiguan'(Pyrus pyrifolia Nakai. cv.Cuiguan) and'Huangguan' (Pyrus pyrifolia Nakai.cv.Huangguan) saplings (Experimental Station of Horticulture, Nanjing Agricultural University in rain shelter) and 10 years old'Hosui'(Pyrus pyrifolia Nakai.cv.Hosui) adult trees (Demonstration orchard of Gaozuo, Suining, Jiangsu) as materials, on pear under different soil moisture conditions in the stem and leaf growth, leaf photosynthesis, leaf relative water content, leaf membrane permeability, leaf SOD activity, proline content, fruit yield and quality and a series of physiological and ecological indicators of the main experimental determination, and physiological indices of these pears and soil moisture content was between analysis. The main results are as follows:1. With the drought stress, the two varieties of shoot length, diameter increased with the decrease of soil water content decreased, the difference between the water treatments were extremely significant or significant, including'Cuiguan'of the new shoot growth was significantly greater than 'Huangguan'. With the decrease of soil water content, leaf area became smaller and smaller,'Cuiguan' pear leaf area at the largest decline in mild drought, while the'Huangguan'pear leaf area from moderate drought at the beginning of a substantial decline in corresponding data of each treatment were significantly different between. Decreased with increasing soil moisture,'Cuiguan' and 'Huangguan' pear leaves are similar trends in chlorophyll content, showed the first decrease and then increase the trend of 'Cuiguan' and 'Huangguan' in the chlorophyll content moderate drought and mild drought reaches the lowest value, followed by rapid increase in chlorophyll content of two varieties are in extreme drought at the maximum, including 'Huangguan' chlorophyll content increased as the drought stress is more rapid increase in the rate of Significant.2. In process of drought stress, leaf net photosynthetic rate, stomatal conductance and transpiration rate were decreased for both varieties; intercellular CO2 concentration was first reduced and then increased in'Cuiguan' leaf, while it showed a consistent downward trend in'Huangguan', however, the 4 parameters in 'Huangguan' were higher than those in'Cuiguan'; photosynthetic parameters of both varieties recovered obviously after rewatering, but could not recover to the normal lever. Drought stress caused sharp decrease for relative water content and increase for membrane permeability and proline content, and trend of increase then decrease for superoxide dismutase activity in leaves of both varieties, although these parameters could more or less recover after rewatering, they could not reach the normal lever. Basing on the comparation on the parameters between these two varieties under drought and rewatering treatments, it was observed that'Huangguan'has stronger to lerance to drought than'Cuiguan'.3. Micro-sprinkler irrigation led the highest soil moisture content in 0-60 cm soil layers, followed by drip irrigation, ridge irrigation, furrow irrigation and CK, micro-sprinkler irrigation's water storage capacity was significantly higher than other irrigation methods; Net photosynthetic rate performance: micro-sprinkler irrigation≥drip irrigation≥ridge irrigation>furrow irrigation>CK, micro-sprinkler irrigation treatment of pear Leaf photosynthetic capacity is the strongest, followed by drip irrigation; The yield of micro-irrigation is the best, followed by drip irrigation, compared with controls, yield per plant rised by 54.98% and 44.18%; Besides, Micro-sprinkler irrigation and drip irrigation could also raise the fruit quality, such as bigger fruit size, higher content of soluble solids and total soluble sugars, lower fruit firmness, lower content of acid and stone cell. It is concluded that, micro-sprinkler irrigation could improve the soil moisture condition and increase the ability of photosynthesis and result in the higher yield and fruit quality more significantly than others, which is an ideal water-saving irrigation technology.