| Brown spot is considered to be a calcium deficiency disease,and often occurs during the harvest period.Because of its spotin the surface like chicken claw,also known as"chicken claw disease".Calcium transport into the plant by transpiration,because the characteristics of calcium is difficult to move,fruits often show calcium deficiency during growth and development stage.Though forliar application of Ca fertilizer was often used to increase Ca content in fruits,the physiological diseases could not have been effectively prevented.,which indicates that there may be other factors other than calcium D-Glucosamine hydrochloride is widely used in agriculture because of its good safety.This study aimed to evaluate the effects of different application of cooperative calcium treatments on fruit quality,antioxidant capacity and mineral nutrient content of 'Huangguan pear,so that it could to provide theoretical basis for reducing incidence of brown spot disease.The main results are as follows:Compared with the control,different application of calcium could significantly improve the activity of peroxidase(POD)and superoxide dismutase(SOD),and decrease the activity of polyphenol oxidase(PPO)on both healthy and diseased fruits peel under induced conditions.During the young fruit stage and fruit expanding stage,chelated calcium combined with D-Glucosamine hydrochloride treatment increased activities of POD and SOD by 27%and 69%respectively,and decreased the activity PPO by 17%in the peel of diseased fruits.All the four calcium treatments were found to increase the calcium content while decreased the potassium,magnesium and phosphorus content of peel on both healthy and diseased fruits.In peel of diseased fruits,calcium content by Ca treatment and Ca+D treatment during fruit stages of young and expansion increased by 24%and 23%than control while potassium content decreased by 10%and 16%respectively.Furthermore,Ca+D treatment decreased magnesium content by 13%than control during the young fruit stage and fruit expanding stage.All calcium treatments could effectively reduce the incidence of brown spot of Huangguan pear fruit,in which the effect of Ca + D treatment was found to be the most significant in the whole growth period compared with control under induced conditions.The incidence of brown spot on 'Huangguan' pear fruit was significantly decreased by 82%.In the field experiment,in diseased fruits,105d after full bloom,POD in peel by Ca+D treatment was the highest,which is 53%higher than control,and the POD activity in flesh was 50%higher than control.The PPO activity decreased by 23%and by 15%in peel and flesh,and the activity of SOD increased by 52.24%and by 43%in peel and flesh.125d after full bloom,the content of MDA decreased by 34%and 31%by calcium conbined D-Glucosamine hydrochloride than control.Compared with control,in diseased fruit peel,with the treatment of Ca+D calcium content in stalk-end increased by 48%,potassium content decreased by 14%,phosphorus content decreased by 20%,magnesium content decreased by 20%;and in calyx-end,calcium content increased by 71%,potassium content decreased by 14%,phosphorus content is reduced by 20%,magnesium content decreased by 17%.In flesh,calcium content increased by 17%,potassium content decreased by 8%,phosphorus content decreased by 20%,magnesium content decreased by 15%in stalk-end;calcium content increased by 30.01%,potassium content decreased by 12%,phosphorus content decreased by 16%,magnesium content decreased by 17%in calyx-end.In diseased fruits,compared with the control,Ca+D treatment increased apoplast calcium in peel by 9%,apoplastic potassium increased by 37%,phosphorus content increased by 33%;Ca+D treatment increased potassium content by 48%,content of apoplastic phosphorus increased by 29%in flesh.the incidence rate was 11.11%with Ca+D treatment,anddecreased by 60%compared with the control.In conclusion,the application of Ca+D was the best in the growth and development of Hanguang pear,which could effectively improve the antioxidant capacity and stress resistance of the fruit and reduce the incidence brown spot.And it could provide the theoretical basis and practical measures for the occurrence of brown spot in pear. |
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