疏果对梨果实糖积累及叶片光合特性的影响

 以‘丰水’梨为材料，研究不同疏果程度和疏果时期对果实糖积累及源叶光合特性的影响，结果表明：随着疏果程度增加，果实单果质量、可溶性总糖含量均显著提高，重度疏果、中度疏果与不疏果（对照）相比，单果质量分别增加172.5%和95.9%，可溶性总糖含量分别增加31.8%和20.7%。疏果对可溶性总糖组分的影响主要是增加蔗糖和山梨醇含量；重度疏果、中度疏果与不疏果（对照）相比，蔗糖含量分别增加134.8%和91.5%，山梨醇含量增加53.2%和26.7%，葡萄糖含量减少45.0%和22.7%。不同时期疏果与不同疏果程度相似，表现为疏果早的果形大，蔗糖和山梨醇含量高，花后90 d重度疏果仍能提高果实糖积累水平。花后80 d不疏果的叶片净光合速率最高，而花后110 d则相反，重度疏果的处理最高。花后110 d不疏果果台副梢叶片的叶绿体嗜锇颗粒增多，片层结构模糊，说明不疏果植株叶片在后期光合速率下降与叶绿体结构改变及其衰老有关。

Effects of Fruit Thinning on Fruit Sugar Accumulation and Leaf Photosynthetic Characteristics of Pear

This study was carried out to investigate the effects of fruit thinning on fruit sugar accumulation and leaf photosynthetic characteristics in pears（Pyrus pyrifolia Nakai.‘Hosui’）. Plants grown in the field were subjected to heavy-thinning（HT treatment），moderate-thinning（MT treatment）and non-thinning（control）. Results showed that single fruit mass in HT and MT treatments increased significantly by 172.5% and 95.9% respectively compared with control，and total soluble sugar content also increased by 31.8% and 20.7% respectively. The components in total soluble sugar were also found to be affected，sucrose content increased by 134.8% and 91.5% in HT and MT treatments compared with control，and sorbitol content increased by 53.2% and 26.7%，while glucose content decreased in HT treatment by 45.0% and 22.7% to other two treatments. Fruit thinning at different stages showed similar effects as above treatments，earlier thinning could result in higher content of，even 90 days after anthesis（DAA），fruit thinning can still promote the sugar accumulation. As for leaf photosynthetic metabolism，leaves on bourse shoot in control treatment could maintain the highest net photosynthetic rate（P_n）till 80 DAA，however it decreased sharply at 110 DAA. Under an electron microscope，increased osmiophilic particles of chloroplasts and fuzzy lamellar structure were observed in the leaves of control treatment at 110 DAA，which was considered to be related to the drop of photosynthetic rate and leaf senescence.