耐裂性不同的西瓜发育过程中果实力学特性及果皮结构动态研究

Study on Fruit Mechanical Properties and Peel Structure during Development of Watermelon with Different Crack Tolerance

【目的】了解耐裂和易裂西瓜果实发育过程中的力学特性和果皮结构变化规律,揭示西瓜耐裂性与果皮结构及果实力学特性的关系,为耐裂西瓜品种选育提供理论依据。【方法】以耐裂种质S1111和易裂种质201609019为试验材料,采用质构仪分析其不同发育时期的果实硬度、果实裂应力变化;利用石蜡切片法观测其果皮结构组织变化。【结果】在果实发育过程中,S1111的果实硬度和裂应力分别是201609019的1.35~1.54倍和1.85~6.03倍,差异显著。组织学研究表明,S1111与201609019的果皮组织结构具有明显差异,S1111的果皮细胞排列紧密并具有明显的石细胞团结构,其果皮和外果皮厚度均极显著高于201609019;而201609019的表皮细胞更长、外果皮细胞和中果皮细胞更大,细胞面积显著大于S1111,其外果皮细胞和中果皮面积分别是S1111的1.67~3.28倍和2.77~5.69倍。相关性分析表明,西瓜果实硬度和果实裂应力与果皮厚度、外果皮厚度呈显著正相关,与表皮细胞长度、外果皮细胞面积及中果皮细胞面积呈显著负相关。【结论】果实裂应力和果实硬度大小可用于评价西瓜果实耐裂性,且在果实发育后期评价更合适。

【Objective】The study was conducted to understand the mechanical properties of fruits and the changes of peel structure during the development of watermelon with crack tolerance and crack sensitive watermelon and reveal the relationship between watermelon crack tolerance and peel structure and fruit physical properties,providing a theoretical basis for the breeding of watermelon with crack tolerance.【Method】Taking crack tolerant germplasm S1111 and crack sensitive germplasm 201609019 as test materials,fruit hardness and crack stress at different development stages were analyzed by texture analyzer.The structure of peel structure was observed histologically by paraffin sectioning.【Result】In the process of fruit development,the fruit hardness and crack stress of S1111 were 1.35-1.54 times and 1.85-6.03 times those of 201609019,respectively,with significant differences.Histological observation showed that there were obvious differences between the peel structures of S1111 and 201609019,The peel cells of S1111 were closely arranged with obvious sclerenchyma structure.The peel thickness and exocarp thickness of S1111 were significantly higher than those of 201609019.While the epidermal cells of 201609019 were longer,exocarp cells and mesocarp cells were larger,and the cell area was significantly larger than that of S1111,and the areas of exocarp cells and mesocarp cells were 1.67-3.28 times and 2.77-5.69 times those of S1111 respectively.Correlation analysis showed that fruit hardness and fruit crack stress were significantly positively correlated with peel thickness and exocarp thickness,but negatively correlated with epidermal cell length,exocarp cell area and mesocarp cell area.【Conclusion】The analysis on fruit hardness,fruit crack stress and peel structure of watermelon showed that the crack stress and fruit hardness could be used to evaluate the crack tolerance of watermelon fruit,and it was more appropriate to evaluate the fruit at the later development stage.