Effects Of Different Summer Pruning Methods On Citrus Tree Growth And Fruit Quality

As two late-ripening citrus varieties,Lane Late navel orange and Orah are of great significance to ensuring the annual supply of fresh citrus fruits in China,and play an active role in the rural revitalization of the Three Gorges Reservoir area and Guangxi Zhuang Autonomous Region.Pruning can control canopy volume,adjust the fruit yield,and improve the ventilation and light transmission performance.However,due to the lack of labor,labor-saving pruning needs to be implemented urgently.In addition,cutting one of the pruning methods,can promote unified and robust branches.In the experiment Lane Late navel orange and Orah were used as materials to explore the effects of mechanical pruning and various cutting degrees on tree growth and fruit quality.The main results are as follows:1.Effects of different summer pruning methods on the growth of citrus treesThe tree height,crown width,and canopy volume of pruned plants were significantly reduced,and the relative growth was mechanical pruning > mild cutting back > heavy cutting back > no pruning > summer shoot thinning.Summer pruning promoted the average autumn shoot length,diameter and number of leaves were all heavy cutting back> mild cutting back> mechanical pruning > no pruning > summer shoot thinning,summer shoot thinning treatment autumn shoot internode length was the shortest,and the relative chlorophyll content of leaves had no significant change.Summer pruning plants had more autumn shoots,the density of autumn shoots was higher,and the number of autumn shoots at a cutting end were summer shoot thinning > mild cutting back>mechanical pruning > heavy cutting back.Different cutting back degrees corresponded to different autumn branch types;there was no difference in morphological differentiation of buds of mature autumn shoots.Summer pruning reduced the number of flowering branches and flowers,and increased the number of leafy flowering branches on the autumn shoots.,summer shoots thinning plants had the largest number of leafy flowering branches.Summer pruning reduced the number of fruit set,and the germination of summer shoots.the fruit setting rate increased with the deepening of cutting back;fruit thinning could significantly promote summer shoots.The results of correlation analysis showed that the thickness of the mother branch of autumn shoots had a very significant positive correlation with the number of leafy flowering branches and the number of fruit set.2.Effects of different summer pruning methods and fruit thinning treatments on fruit quality of citrusSummer pruning plants yield were thinning summer shoot > mild cutting back>mechanical pruning > no pruning > heavy cutting back> fruit thinning,fruit number were mechanical pruning > mild cutting back> no pruning> Summer shoot thinning>heavy cutting back> fruit thinning treatment,the proportion of large fruit above 70 mm in summer shoot thinning,mild cutting back and fruit thinning treatment increased,and the proportion of small fruit less than 70 mm in mild cutting back and mechanical pruning increased;The internal quality,appearance quality,fruit size,peel firmness,thickness,and toughness of mature fruits under different treatments were not significantly different.In addition,pruning could delay fruit coloring and sugar accumulation.3.Effects of mechanical pruning on tree growth and orchard scene of Lane Late navel orangeMechanical pruning had obvious effects on reducing the cross of branches between rows,increasing the operating range between rows and regulating the orchard scene,and at the same time,the ventilation and light transmission between rows are also significantly enhanced;pruning can promote more autumn shoots and fruiting mother branches,and improve the fruiting branches.The number of leafy fruiting branches on it lays the foundation for a high yield in the coming year.