关键词: 辣椒, 种质资源, 果实质地, TPA法, 细胞壁组分

Abstract:

【Objective】As a widely cultivated vegetable crop in the world, the fruit texture of pepper has a significant impact on quality, storage, transportation and market acceptance. By establishing the evaluation system on fruit texture, it provides a theoretical and practical basis for quality breeding, cultivation management and postharvest treatment in pepper. 【Method】Texture profile analysis was used to determine the hardness, fracture, adhesiveness, cohesiveness, gumminess, springness and chewiness for pepper fruit of 96 germplasm resources at the green maturity stage. Combining the correlation analysis, principal component analysis and cluster analysis, the comprehensive evaluation model was established and the specific pepper germplasm was screened. The content of cell wall substances was measured to explore its correlation with texture indexes.【Result】The texture indexes of pepper fruit were significantly different among different germplasms. The diversity index was over 3.7, which indicated that the germplasm resources were rich in variation. The texture indexes were mutually affected, and the hardness was significantly positively correlated with elasticity, viscosity and chewiness. Two factors affecting the texture of pepper fruit including toughness and viscosity with a cumulative contribution rate of 70.465% were extracted by principal component analysis. A comprehensive evaluation model to the texture quality of pepper fruit W=0.691W1+0.309W2 was established, and the specific germplasm with the highest comprehensive evaluation score (No. 63) and the lowest score (No. 29) were selected. Based on the 7 texture indexes and W values, 96 pepper germplasms were divided into 5 groups by cluster analysis, and there were significant differences among the indexes of each group. 4 germplasms with high hardness, strong springness and relatively high W value, were included in group I, which were hard and upright lantern type. While 3 germplasms with low fracture, weak gumminess and relatively low W value were included in group V, which were soft and wrinkled type. The texture indexes and W values of the germplasm in class Ⅱ, Ⅲ, and Ⅳ were in the middle. The contents of cellulose, hemicellulose, total pectin and lignin were normally distributed in the cell wall components in 96 pepper germplasms, indicating that the tested germplasm was rich in diversity. There was a significant correlation between cell wall components and TPA indexes. Cellulose is significantly positively correlated with hardness, and lignin was positively correlated with hardness, adhesiveness, chewiness, fracture and springness, while total pectin is negatively correlated with hardness and adhesiveness. 【Conclusion】Hardness, springness, gumminess and chewiness are the key indexes to judge the texture of pepper fruit, and the cell wall components have an important impact on the quality of fruit texture. Specific germplasm on texture quality in pepper fruit could be identified using the comprehensive evaluation model W=0.691W1+0.309W2 established in this study.

Key words: pepper (Capsicum annuum L.), germplasm resources, fruit texture, TPA method, cell wall components