石榴冷害与病害生理及调控技术研究

发布时间：2018-01-30 04:18

  本文关键词： 石榴 冷害生理 茉莉酸甲酯 病害 壳聚糖　出处：《天津科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：冷害、褐变、腐烂、失水是影响石榴采后保鲜品质的重要因素。石榴为低温敏感性果实,不正常低温极易导致果实冷害,影响果实外观,加速果皮褐变及果实腐烂,而影响果实冷害、病害的因素包括品种、产地、采收期、贮藏条件等。本试验以云南蒙自甜石榴为试材,研究果实冷害温度与冷害生理变化,研究MeJA对石榴冷害的调控作用,通过对果实采后病原微生物分离、纯化、鉴定,确定石榴采后优势致病菌,通过壳聚糖涂膜保鲜,确定壳聚糖对主要致病菌抑制效果及保鲜效果,确定果实低温保鲜最佳成熟度、包装方式、气调气体浓度,指导石榴采后保鲜。通过冷害指数评估确定果实在1℃贮藏时,出现明显冷害症状,其中0℃果实贮藏20d时表现轻微冷害,130d时,冷害指数高达0.54,果皮出现凹陷褐斑,而3℃、4℃贮藏加快果皮褐变和果实腐烂,确定1℃为果实冷害温度,2℃为最适贮藏温度。低温冷害破坏了石榴果皮结构,果皮表面出现裂痕,表皮粗糙,蜡质层减少,失重率增加,破坏果皮细胞膜结构,细胞膜透性、丙二醛含量增加,0℃贮藏果实呼吸速率异常升高,贮藏40d时出现呼吸峰值,之后呼吸强度下降,130d时,细胞膜透性达到57.46%,丙二醛含量23.47umol/g. Fw,低温冷害及相对高温均加快果皮褐变,褐变与果实多酚含量、PPO活性密切相关,褐变指数与多酚含量、PPO活性相关系数(R2)分别为0.821、0.729。MeJA提高果实可溶性蛋白含量,增强果实抗病性,0.1mmol/L MeJA处理果实褐变指数、腐烂率较CK分别降低39.48%,29.61%,有效保持了果实外观及营养品质。经过病原微生物分离、纯化、鉴定,确定3种优势致病菌,包括曲霉属黑曲霉(Aspergillus niger)、青霉属变紫青霉(Penicillium purpurescens)、葡萄座腔菌属(BotryosPhaeria),黑曲霉为采后田间病原菌,采后分离率高,贮藏期可引发果实软腐病,变紫青霉主要出现于采后机械伤部位及冷害病斑部位,病害果实表面霉变或者出现软腐,葡萄座腔菌属主要出现于果实贮藏后期,病害果实表面大面积霉变,病斑褐色、水浸状,是高温贮藏最主要致病菌。壳聚糖对3种优势致病菌均具有良好的抑制效果,1.0%壳聚糖处理果实贮藏130d时,腐烂率为4.4%,较CK降低45.68%,失重率为2.24%,果实外观良好。石榴为非呼吸跃变果实,低温贮藏果实应适时晚采,其中8-9成熟果实可有效降低果实采后果皮褐变现象的发生,采后用0.02mm PE保鲜膜包装或O2：4%,CO2：5%气调处理,可有效保持果实外观品质。
[Abstract]:Cold damage, browning, decay and water loss are important factors that affect the quality of postharvest pomegranate. Pomegranate is sensitive to low temperature, and abnormal low temperature can easily lead to cold damage and affect the appearance of the fruit. The factors affecting fruit chilling damage include variety, origin, harvest period, storage conditions, etc. In this experiment, Mengzi sweet pomegranate from Yunnan Province was used as the test material. The temperature and physiological changes of fruit chilling injury were studied, and the regulation of MeJA on pomegranate chilling injury was studied. Through the isolation, purification and identification of postharvest pathogenic microorganisms, the dominant pathogen of pomegranate was determined. Through chitosan film preservation, the inhibition effect of chitosan to the main pathogenic bacteria and the preservation effect were determined, and the best maturity, packaging method and atmosphere concentration of fruit preservation at low temperature were determined. To guide the postharvest preservation of pomegranate. Through the evaluation of chilling injury index, the fruit showed obvious chilling injury symptoms when stored at 1 鈩，

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