Effects Of Crown Cutting On Crown Remodeling,flowering,and Fruiting Of Cupressus Funebris

The seed orchard is an important base for obtaining superior seeds and represents an advanced form of tree improvement.Compared to other common seed sources,it offers higher genetic gains and is considered an indispensable tool in tree breeding.However,existing seed orchards,including the cypress seed orchard,built using the timber forest model,face challenges such as low seed yield,high fruiting positions,and difficulties in utilization.Crown pruning can significantly reduce the height of fruiting and make harvesting easier,but its effectiveness depends on the intensity of pruning.Therefore,in order to enhance the production potential of this type of seed orchard,different crown pruning intensities were applied to the mother trees in the 1.5th generation seed orchard of the Baiyunzhai National Superior Cupressus funebris Germplasm Base in Peng’an County.The objective was to understand the effects of crown pruning on the crown growth,female flower quantity,fruit set quantity,fruit quality,fruiting position,photosynthetic characteristics,leaf chlorophyll,and nutrient elements of the cypress mother trees.This research aimed to provide a basis and technical reference for the management of mother tree individuals in the seed orchard and enrich the content of seed orchard management in China.The main research results are as follows:(1)Mild and severe crown pruning can significantly reduce the crown length of the mother trees while promoting crown width growth.The increase in crown width for mild and severe crown pruning was 2.83 and 3.17 times that of the control group,respectively.The effective increase in crown width was 9.33 and 12.11 times that of the control group,respectively.This helps the cypress trees establish a well-balanced flat-spherical crown structure,increases the utilization of space by the mother trees,promotes their healthy growth,and lowers the harvesting height.(2)Crown pruning can promote an increase in male and female cone quantity in the lower part of the tree,shifting their spatial distribution downward.The promotion effect becomes more significant with increasing years of crown pruning.Severe crown pruning has a stronger effect on promoting male and female cones in the lower part of the tree.In2021 and 2022,the quantity of female cones in the lower part of the tree was 43.70% and86.86% higher,respectively,for severe crown pruning compared to the control group.The quantity of male cones was 85.32% and 147.91% higher,respectively.(3)Both mild and severe crown pruning can increase the individual fruit weight,horizontal and vertical diameter of the mother tree cones,as well as the quantity of cones per unit volume.This improves the quality and yield of cypress mother tree cones,makes the distribution of cones more uniform throughout the tree,and facilitates harvesting.Regarding individual fruit weight,severe crown pruning achieved the highest increase,reaching 26.48%,while mild crown pruning had a higher increase in the quantity of cones,reaching 73.99%.Crown pruning can also increase the weight of 100 seeds and improve the germination capacity and uniformity of lower-layer seeds,enhancing the sowing quality of the seeds.Severe crown pruning had a higher seed weight increase,reaching24.34%,while mild crown pruning had a higher increase in seed germination rate,reaching60.30%.(4)Crown pruning treatments have a certain promoting effect on the photosynthetic capacity of lower-level Cupressus funebris leaves and the absorption of phosphorus(P)and potassium(K)elements in the leaves,with no significant difference between severe and mild crown pruning.(5)A comprehensive evaluation of the two crown pruning intensities resulted in scores of 22.13 and 42.17 for mild and severe crown pruning,respectively,both higher than the score for the control group.This indicates that crown pruning has a certain promoting effect on the crown shape,cone quantity,fruit quality and quantity,seed quality,photosynthetic capacity,and leaf nutrient absorption of cypress trees,with severe crown pruning showing better promoting effects.In conclusion,crown pruning has a significant impact on the reshaping of the Cupressus funebris tree crown and flowering and fruiting.Scientific crown pruning can promote the formation of an ideal crown shape,enhance flowering and fruiting,improve seed quality,and lower the fruiting position of cones.The research results can provide reference for the management of similar Cupressus funebris seed orchards in terms of tree individuals.