Effects Of Different Leaf-fruit Ratio On Fruit Quality And Leaf Characteristics In ‘xueqing’ Pear

Nowadays, many pear orchards in our country face the same problem. To be specific, the yield of pears has increased but the fruit has lower quality. This experiment with 6-year-old,field grown pear trees as testing materials, in order to promote the balance between source and sink as the breakthrough point, trees grown in the field were subjected to three treatments, leaf-fruit ratios(L/F ratio) were adjusted(35~50):1,(25~30):1 and(10~15):1(as control). This study was carried out to investigate the effects of different L/F ratio on the fruit quality and the dynamic variation of photosynthesis, fluorescence chlorophyll parameters and mineral elements content in ‘Xueqing’ pear. We want to identify the optimal L/F ratio so that we could provide a theoretical basis for improving the quality and yield of fruit. Results showed as follows:1. The L/F ratio(35~50):1 treatment and the L/F ratio(25~30):1 treatment compared with L/F ratio(10~15):1, the fruit mass increased significantly by 88.11% and 51.75% respctively; total soluble sugar increased by 36.85% and 24.41% respctively; sucrose increased by 129.89% and 73.99% respctively; glucose increased by 40.25% and 37.14%; fructose increased by 22.98% and 14.63%; soluble solids content increased by 36.15% and 22.70%; soluble protein content increased by 26.65% and 21.40%, while fruit firmness decreased significantly by 13.15% and 10.33%; titrable acid decreased by 16.15% and 17.85%, starch content decreased significantly by 49.68% and 50%. The Vc content has no significant difference in all treatments.The L/F ratio(35~50):1 treatment compared with control, the yield decreased significantly by 41.73%, the yield had no significant difference between the L/F ratio(25~30):1 treatment and the control.2. In all treatments, the net photosynthetic rate(Pn) of leaves were increased and then decreased, mainly, the net photosynthetic rate(Pn) of leaves increased with the rise of leaf-fruit ratio; compared with Pn, basically, the stomatal conductance(GS) and the transpiration rate had the same trend in the whole stage, while the intercellular CO2 concentration(Ci) appeared relatively stable, compared with Pn, it had the contrary trend variation in many stages during this experiment.3. In this experiment, Fv/Fm of leaves increased with the rise of leaf-fruit ratio, but there were no significant difference in all treatments; ΦPSⅡof leaves increased at early stage and decreased at the late stage, ΦPSⅡof leaves increased with the rise of leaf-fruit ratio in principle; compared with ΦPSⅡ, q P, q N had the same tendency in the whole stage; as for the ETR of leaves, there was not a rule can be followed.4. In all treatments, the content of N were increased and then decreased, it increased with the rise of leaf-fruit ratio; compared with the variation tendency of Mg, the content of Ca, K, Mg, Mn and B had the same trend during experiment.However, the content of Fe, Zn didn’t have obvious regularity.With ageing of the leaves,the content of Ca increased than before.