不同板栗品种坚果果皮结构差异及其与腐烂指数的相关性分析OA北大核心CSTPCD

[Objective]This study aimed to elucidate the structural characteristics of the nut pericarp in different chestnut varieties and their relationship with the decay index,identifying key pericarp structural indicators that influence chestnut decay.This research provides a reference for the evaluation,selection,and scientific storage of chestnut germplasm resources resistant to decay.[Method]Nuts from six chestnut cultivars planted in Qianxi County,Hebei Province('Libozaoli','Bayuehong','Mingjian','Taili 1','Yanshanzaofeng',and'Dabanhong')were used as experimental materials.A low-temperature storage experiment(0～2 ℃)was conducted over 180 days,with nut rot conditions surveyed every 30 days.Pericarp samples from both intact nuts before storage and rotted nuts during storage were fixed for structural observation using the paraffin section method.This facilitated analysis of pericarp structural and differences among different chestnut cultivars,changes in the structure of rotted nut pericarps,and the correlation with the decay index.[Result]1)Significant differences in the decay levels were observed among chestnut cultivars during storage.'Mingjian','Taili 1','Yanshanzaofeng',and'Dabanhong'showed higher storage resistance with an average rot index of 9.35％,whereas'Bayuehong'and'Libozaoli'were more prone to rot,with rot indexes reaching 23.53％and 21.63％,respectively.2)Significant differences in pericarp structure were noted among the varieties.'Mingjian','Taili 1','Yanshanzaofeng',and'Dabanhong'had thick cuticle layers,small and regular epidermal cells,and highly dense mesocarp and endocarp layers.'Bayuehong'and'Libozaoli'had thin cuticle layers,larger epidermal cells,with'Bayuehong'showing clear gaps in the epidermal cell layer,whereas'Libozaoli',despite a tighter epidermal cell layer,had less dense mesocarp and endocarp layers.Compared to intact fruits,decayed fruits showed a significant reduction in cuticle thickness,increased gaps in the epidermal,mesocarp,and endocarp layers,and a significant decrease in pericarp density.Specifically,the cuticle layer of decayed fruits from'Libozaoli'and'Bayuehong'nearly vanished,with severe damage to the epidermal layer,and decomposition of the cell walls in the thin-walled cells of the mesocarp,leading to numerous cavities,whereas'Mingjian','Taili 1','Yanshanzaofeng',and'Dabanhong'maintained a certain thickness in the cuticle layer,and their epidermal cell structure remained relatively intact,but more cavities appeared in the middle and inner pericarp layers.3)The analysis of the correlation between the pericarp structural indicators of intact and decayed fruits and the decay index showed that the decay index was significantly negatively correlated with the thickness of the cuticle layer,and significantly positively correlated with the gap rate of the epidermal cell layer and the gap rate of the mesocarp and endocarp layers.It was also negatively correlated with the length-to-width ratio of epidermal cells,but showed no significant correlation with other indicators.4)Based on the four indicators of cuticle thickness,the length-width ratio of epidermal cells,and the cell gap size of the epidermal,mesocarp,and endocarp layers,the membership function method was used for comprehensive evaluation and found that the decay resistance of the six chestnut varieties was ranked from strong to weak as'Mingjian'＞'Taili 1'＞'Yanshanzaofeng'＞'Dabanhong'＞'Libozaoli'＞'Bayuehong'.The results were basically consistent with the storage test results.[Conclusion]The thickness of the cuticle layer,the length-width ratio of epidermal cells,and the cell gap size of the epidermal,mesocarp,and endocarp layers are closely related to the occurrence of rot.The above four indicators can be used as an important reference for determining the decay resistance of chestnut.