肉桂精油复合壳聚糖涂膜对采后番木瓜炭疽病的防治效果及作用机制分析

番木瓜是我国著名的热带、亚热带水果之一,但番木瓜属于呼吸跃变型果实,采后不耐贮运,其中由炭疽病引起的腐烂损失最为严重。因此,如何防治番木瓜采后炭疽病,降低番木瓜腐烂损失,延长贮藏保鲜期,成了制约番木瓜产业健康发展的瓶颈问题。本文以‘大青’番木瓜为试验材料,以绿色环保的肉桂精油-壳聚糖复合保鲜液为处理手段,研究其对采后番木瓜炭疽病的防治效果及作用机制,为我国番木瓜采后贮运保鲜产业发展提供理论依据和应用参考。分别用0.5%壳聚糖、0.5%壳聚糖+0.3%肉桂精油、0.5%壳聚糖+0.5%肉桂精油、0.5%壳聚糖+0.7%肉桂精油溶液对采后番木瓜果实进行喷雾处理,清水处理作为对照,处理后的番木瓜分为2组,其中一组处理后置于25℃下恒温贮藏,定期测定果实病情指数;另一组处理后置于25℃下恒温贮藏24 h后,在果面刺伤接种番木瓜炭疽菌,定期调查果实病斑直径,并对果皮进行取样,测定不同处理果实的抗病相关物质含量和抗病相关酶活性的变化情况。番木瓜炭疽菌的离体抑菌实验采用含药PDA平板抑菌法进行测定。研究结果表明:0.5%壳聚糖+0.3%肉桂精油处理对番木瓜炭疽病的防治效果最好,复合处理可完全抑制离体番木瓜炭疽菌的生长和产孢,复合处理显著降低了番木瓜果实的病斑直径,提高了抗病相关物质木质素、总酚(TP)和过氧化氢(H₂O₂)的含量,提高了抗病相关酶苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和β-1,3葡聚糖酶(β-1,3-GA)的活性,但对几丁质酶(CHI)活性影响不大。由此可见,肉桂精油复合壳聚糖涂膜对番木瓜炭疽菌有较好的防控效果,一方面是由于复合处理抑制了番木瓜炭疽菌的生长,另一方面是复合处理诱导番木瓜果实提高了抗病性。因此,适宜浓度的肉桂精油复合壳聚糖涂膜处理为防控番木瓜采后炭疽病提供了一种绿色新途径。

Analysis of Control Effect and Mechanism of Cinnamon Essential Oil Composite Chitosan Coatings on Postharvest Papaya Anthracnose

Papaya is one of the famous tropical and subtropical fruits in China,but papaya is a kind of respiratory climacteric fruit,and is intolerance to storage and transportation after harvest,and the postharvest rot caused by anthracnose is the most serious problem.Therefore,how to control papaya postharvest anthracnose,reduce the postharvest rot,and prolong the preservation period has become a critical restricting the healthy development of the papaya industry.In this paper,‘Daqing’papaya was used as the test material,and the green and environmentally friendly cinnamon essential oil-chitosan composite preservation solution was used as the treating method to study the control effect and mechanism to postharvest papaya anthracnose for the purpose of the development of the storage and preservation industry of papaya after harvest to provide theoretical basis and application reference.In this paper,0.5%chitosan,0.5%chitosan+0.3%cinnamon essential oil,0.5%chitosan+0.5%cinnamon essential oil,0.5%chitosan+0.7%cinnamon essential oil were used on postharvest papaya.The treated method was spraying and treated with water as the control.The treated papayas were divided into two groups,one group was treated and stored at 25℃,the fruit disease index was measured regularly,and the other group was wounded inoculated papaya Colletotrichum gloeosporioides on the fruit surface after stored for24 h at 25℃,and the diameter of the fruit lesions were investigated regularly,meanwhile,the papaya peels were sampled,and the content of disease resistance related substances and the changes of disease resistance related enzyme activity in the fruits were determined.The in vitro anti-fungus experiment of papaya C.gloeosporioides was determined by the drug-containing PDA plate anti-fungus method.The results showed that the treatment of 0.5%chitosan+0.3%cinnamon essential oil had the best control effect on papaya anthracnose,and the combined treatment could completely inhibit the growth and sporulation of C.gloeosporioides in vitro.The combined treatment significantly reduced the diameter of anthracnose lesion on papaya fruit.The content of disease resistance related substances lignin,total phenol(TP) and hydrogen peroxide (H₂O₂) was increased,and disease resistance related enzymes phenylalanine ammonia lyase(PAL),peroxidase (POD) andβ-1,3-glucanase (β-1,3-GA) activity increased,but had little effect on chitinase (CHI)activity.It was clear that cinnamon essential oil composite chitosan coatings had good control effect on papaya anthracnose.The combined treatment inhibited the growth of papaya C.Gloeosporioides and induced papaya fruit to improve disease resistance.Therefore,the appropriate concentration of cinnamon essential oil combined with chitosan coating treatment would provide a new green way to control the postharvest papaya anthracnose.