The effect of preharvest 28.6% chitosan composite film sprays for controlling the soft rot on kiwifruit

Abstract

This study evaluated the effects of preharvest plant 28.6% chitosan composite film (CTS-Fh) sprays on the postharvest quality and diseases in kiwifruit (Actinidia deliciosa cv. ‘Guichang’), it was screened and prepared by mixing chitosan, calcium, dextrin, ferulic acid and auxiliaries. 28.6% CTS-Fh solutions at different concentrations were sprayed three times during the fruit growing season. The obtained results show that 28.6% CTS-Fh sprays remarkably promoted the improvement of the yield and quality of the kiwifruit, significantly (P < 0.05) increased the Ca content and firmness, delayed the fruit ripening and softening, and enhanced the storability. Moreover, the kiwifruit soft rot was effectively controlled; the control efficiency was 61.68–88.79%. Additionally, the 28.6% CTS-Fh sprays significantly (P < 0.05) increased the content and activity of some defence-related secondary metabolites and enzymes, and could also increase the cell wall compactness in the kiwifruit. These results suggest that 28.6% CTS-Fh might trigger several defence responses in the kiwifruit against pathogenic infections. The doses of 28.6% CTS-Fh 200–400 dilution times were recommended for the practical application with regards to the production of kiwifruit.

Preharvest Application of Chitosan Improves the Postharvest Life of ‘Garmrok’ Kiwifruit through the Modulation of Genes Related to Ethylene Biosynthesis, Cell Wall Modification and Lignin Metabolism

“…In our previous study, we showed that the preharvest treatment of calcium chitosan (100 mg·L −1 ) increased the fruit weight with no effect on the size of kiwifruit at harvest [ 8 ]. A recent similar study demonstrated that the preharvest spray of chitosan increased the single fruit weight with the equivalent yield of kiwifruit without affecting the size of the fruit [ 22 ]. Here, we show that the application of preharvest chitosan also increased the fruit weight and delayed maturation and ripening of the kiwifruit.…”

“…The film coating of chitosan on the fruit surface can absorbs moisture due to the hydrophilic nature of chitosan solution [ 34 ] and this could be attributed to the increased weight of kiwifruit, which in turn reduced water loss from fresh fruit. Alternatively, the increased weight of chitosan-treated kiwifruit may be attributed to the activity as a biostimulant and growth elicitor, as demonstrated in Capsicum annuum ‘Yolo Wonder’ bell pepper [ 35 ], Solanum lycopersicon ‘Faridah’ tomato [ 36 ], and A. deliciosa ‘Guichang’ kiwifruit [ 22 ]. Future investigations on the detailed mechanistic insights as to the increased weight of fruits at harvest pretreated by chitosan further awaits.…”

“…Phenolic compounds, the major secondary metabolites in plants, are responsible for the flavor and color of fruits with antioxidant potential [ 22 , 26 , 36 , 42 ]. The (+)-catechin, chlorogenic acid, rutin, (−)-epicatechin, quercetin, and tannin are the major phenolics identified in kiwifruit [ 26 ] and are responsible for the antioxidant capacity of fruit while being involved in the antioxidant metabolism [ 22 , 26 ].…”

“…It is a polysaccharide derived from the deacetylation of chitin [ 6 , 17 , 18 , 19 , 20 ]. It has been shown that the use of chitosan as an edible coating enhances the quality and postharvest life of various fruits owing to its excellent film-forming, non-toxic, biocompatible, biodegradable, and antifungal properties [ 2 , 8 , 18 , 20 , 21 , 22 ]. Besides, several studies have demonstrated that the postharvest use of chitosan as an edible coating maintains quality and extends the postharvest life of kiwifruits such as green-fleshed ( A. deliciosa ) kiwifruit [ 3 , 18 , 23 ], yellow-fleshed kiwifruit ( A. chinensis ) [ 6 , 24 ], red kiwifruit ( A. melanandra ) [ 2 ], hardy kiwifruit ( A. arguta ) [ 13 ], and arctic kiwifruit ( A. kolomikta ) [ 21 ].…”

“…In our previous studies, we evaluated the effectiveness of the application of preharvest chitosan in combination with calcium chloride (Ca-chitosan) that resulted in the enhancement of fruit quality and postharvest life of hardy kiwifruit ( A. arguta ‘Saehan’) [ 25 ] and green-fleshed kiwifruit ( A. deliciosa ‘Garmrok’) [ 8 ]. In a separate study, Zhang et al [ 22 ] reported that the preharvest spraying of chitosan composite films (chitosan, calcium, dextrin, ferulic acid, and auxiliaries) had several positive effects on the postharvest quality and control of diseases in kiwifruit ( A. deliciosa ‘Guichang’). Although these results suggest the efficacy of preharvest treatment of chitosan in maintaining the postharvest properties of kiwifruit, the physiological changes and underlying molecular events involved in maintaining fruit physicochemical properties need to be further investigated.…”