Effects of Thinning and Retracting Pruning on Branch Growth and Photosynthesis of"Shifeng"Chestnut
Poor ventilation,light opacity and crowded living space are common problems in perennial chestnut orchard.In order to improve the growth conditions of perennial chestnut trees,thinning and retracting pruning were used to trim and modify the tree shape of chestnut orchard,and the effects of thinning and retracting pruning technology on the growth of chestnut branches and photosynthesis were explored to improve the ventilation and light transmission of chestnut orchard.Alleviate the closure of perennial chestnut orchard and promote the healthy growth of chestnut trees.In this experiment,the 23 year old"Shifeng"chestnut garden was selected as the experimental area,and the chestnut garden was thinned and pruned.The chestnut trees that were thinned and pruned were used as the treatment and the normal growing chestnut trees were used as the control to observe and measure the growth of chestnut branches.The net photosynthetic rate,transpiration rate,intercellular CO2 concentration and stomatal conductance of leaves in the upper,middle and lower parts of chestnut canopy at 8:00,10:00 and 16:00 were measured by TARGAS-1 portable photosynthesis measurement system,and variance and significance analysis were performed.The results showed that(1)Thinning and retracting pruning significantly reduced the crown diameter of chestnut.(2)Thinning and retracting pruning significantly promoted the growth of new shoots,increased the length of new shoots and increased the thickness of new shoots.(3)After thinning and retracting pruning,the net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci)and transpiration rate(Tr)of chestnut were significantly increased.(4)Thinning and retracting pruning had a more significant effect on photosynthesis in the lower and middle part of the chestnut canopy.(5)Thinning and retracting pruning is more effective at 16:00.Thinning and retracting pruning can reduce the crown diameter and the closure of chestnut orchard,increase the length and thickness of new shoots.At the same time,thinning and retracting pruning could improve the light transmittance of chestnut orchard,enhance the light degree of chestnut and enhance the photosynthesis of chestnut.
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