Effects Of Leaf-fruit Ratio On Photosynthetic Characteristics In Leaves And Assimilate Transport And Distiribute Of Walnut

Walnut is one of the tree species for the purpose of harvesting nuts in economic forest fruit trees.J.regia’Xinxin 2’walnut is one of the main varieties of Walnut in the southern basin of Xinjiang.In the investigation,it was found that the imbalance of the proportion of leaf-to-fruit ratio in the natural state of early fruity walnut in Xinjiang resulted in a serious phenomenon of small walnut fruit and incomplete kernel,which greatly reduced the economic benefit of walnut per unit area and hindered the pace of improving quality and efficiency of walnut industry in Xinjiang.The leaf-to-fruit ratio is closely related to the photosynthetic characteristics of walnut leaves and assimilate distribution.Therefore,reasonable load of fruit trees is the premise of realizing high-yield and high-quality production of fruit trees.In view of this,this paper takes J.regia’Xinxin 2’walnut as the research object,compares and analyzes the differences between the photosynthetic characteristics of leaves,carbohydrate transport characteristics of fruit stalks and fruit quality of walnut branches with different leaf-to-fruit ratio,and explores the relevant physiological mechanisms of photosynthetic characteristics and assimilate distribution of walnut leaves with different leaf-to-fruit ratio,so as to provide a theoretical basis for determining the reasonable load.The main research results are as follows:（1）The leaf-to-fruit ratio has a significant effect on the photosynthesis of walnut leaves（P<0.05）.When the leaf-to-fruit ratio was 1L:2F,1L:3F and 3L:3F,the carboxylation efficiency of leaves decreased due to excessive load.As a result,the CO₂reduction and fixation capacity of branches and leaves decreased.Non stomatal factors were the main reason for the down regulation of net photosynthetic rate（Pn）.When the number of leaves on fruit branch is 5,appropriate increasing of the fruit load on fruit branch is conducive to stimulate the potential photosynthetic capacity of the leaves.（2）The leaf-to-fruit ratio had significant effect on walnut’s carbohydrate transport（P<0.05）.When the leaf-to-fruit ratio was 1 or 3,the excessive fruit load（1L:2F,1L:3F,3L:3F）suppresses the development of the stalk and vascular tissue,resulting in the decline of the stalk vascular bundle assimilate transport rate.When the number of leaves on the fruiting branch was 5,then increasing the fruit load appropriately is beneficial to promote the transport of leaf photosynthetic assimilates to the fruit.（3）The leaf-fruit ratio had a significant effect on the quality of walnut fruit（P<0.05）.When the leaf-fruit ratio was 1L:2F,1L:3F and 3L:3F,the physical and chemical quality of fruit decreased.When the number of leaves on fruiting branch was 5,the increase of fruit load had no significant effect on the longitudinal diameter,oil content and soluble protein content of walnut fruit（P<0.05）.When the leaf-fruit ratio was 3L:1F,5L:1F,5L:2F,the single fruit weight of walnut was high and the fruit quality was good.（4）The suitable leaf-fruit ratio of Juglans regia’Xinxin 2’walnut is 3L:（1-2）F,5L:（1-3）F,so scientific regulation measures of leaf-fruit ratio can be adopted to promote the coordinated development of walnut source and sink,so as to achieve high yield and high quality production.