Study On Photosynthetic Characteristics,quality And Carbon Fixation Capability Of Kiwifruit In Different Tillage Ways

In order to scientifically evaluate the three tillage ways in the study area:cleaning underneath as control（CK）,pruned branches returning to the field（S1）and planting grasses between trees（S2）,we selected the variety of‘Xuxiang’kiwifruit trees in Mei county as the study material.We measured leaf area,gas exchange parameters,light response curve and CO₂response curve in the early growth stage,vigorous period and senescence stage of kiwifruit leaves.We analyzed the differences in photosynthetic characteristics of kiwifruit leaves under three tillage ways.We also estimated the photosynthetic carbon fixation capacity of kiwifruit plants from a certain leaf area level and the level of a whole plant.After the fruit matures,we measured the fruit quality.The results of the study can provide some reference for the selection of reasonable tillage ways for kiwifruit orchards,and provide new ideas for dealing with global climate change.The main results of the study are as follows:（1）We studied the effects of tillage ways on the photosynthetic characteristics of kiwifruit leaves.The results showed that S1 and S2 enhanced the adaptability of kiwifruit plants to the environment,mainly as follows:These two tillage ways can significantly alleviate the stomata limitation of kiwifruit leaves.During the period of vigorous growth of leaves,the stomatal limit values of S1 and S2 at 14:00 were 19.20%and 15.70%lower than CK,respectively.Kiwifruit leaves have a certain improvement in the ability to utilize CO₂ and regulate the transport of water.The net photosynthetic rate of the leaves is significantly improved,which facilitates the accumulation of photosynthetic products.During the senescence stage of leaves,the daily average net photosynthetic rate of S1 and S2 was 32.43%and 35.85%higher than that of CK,respectively.（2）The light response curve and CO₂ response curve of kiwifruit leaves under different tillage ways were analyzed.The results showed that the tillage treatment was conducive to the expansion of the utilization of light energy by kiwifruit plants.The difference between the light saturation point and the light compensation point of S1 and S2 during the period of vigorous growth of leaves is 12.85%and 15.75%higher than that of CK,respectively.S2 can increase the maximum net photosynthetic rate of kiwifruit leaves under light saturation,which is beneficial to the improvement of photosynthesis potential.In addition,S1 and S2significantly increased the utilization efficiency of kiwifruit leaves for CO₂.At the beginning of the growth of kiwifruit leaves,the photosynthetic capacity of S1 and S2 was 21.26%and19.90%higher than that of CK,respectively.（3）For the three periods of leaf growth,the photosynthetic carbon fixation of kiwifruit leaves was calculated.The results showed that the tillage measures significantly improved the photosynthetic carbon sequestration capacity of kiwifruit plants.During the whole growing season,the daily net carbon sequestration of a certain leaf area kiwifruit plants under different tillage ways showed S2>S1>CK,and the daily net carbon sequestration of a whole kiwifruit plants showed that S1 and S2 were higher than CK.The annual carbon sequestration of a whole kiwifruit plants was calculated as S1 and S2 were 54.92%and 31.59%higher than CK,respectively.（4）The results of kiwifruit fruit quality test showed that S1 and S2 can improve the fruit quality of kiwifruit to different extents.The vitamin C content in the fruit was significantly improved.The vitamin C content of S1 and S2 was 22.76%and 12.77%higher than that of CK,respectively.The sugar content and the ratio of sugar to acid in the fruit also improved.S2 is also beneficial to the improvement of the appearance quality of kiwifruit fruit,making it more beautiful.