Dynamic Changes of Fruit Shape Traits and Its Correlation to the Morphology of Other Organs in Cucumber

Abstract

Fruit shape and size are important assessment parameters to evaluate and classify accessions in cucumber breeding. Clarifying the relations of the shape and size of commodity fruits or mature fruits to that of other organs, like seed, leaf, flower and so on, is significant for multitype breeding of cucumber fruit. It can help breeders to predict the shape and size of a cucumber fruit in the early selection and shorten the breeding cycle. In this study, the dynamic morphological observation of fruit length (FL), fruit diameter (FD) and the fruit shape index (FSI) of developing cucumber fruits in different types and the correlation of fruit shape indexes between fruit and other organs were investigated. The results showed that 28 cucumber accessions with different shape and size were classified into four types, namely long fruits, medium long fruits, medium fruits and short fruits. The comparative analysis of FL and FD among different types and different development stages of cucumber fruits showed that the development of FL and FD were both consistent with the model “S” curve, slow–fast–slow, and there existed strong positive correlation between their growth. During fruit development, the shape index was highly positively correlated among ovary, commodity fruit and mature fruit. Besides, both the length and width of cotyledon, true leaf and female flower petal were positively correlated to the FL of commodity fruit. The length and width of seed, length of ovary carpopodium and pedicel length were also positively correlated to the FD of commodity fruit. For seed, cotyledon and true leaf, no correlation was found between their shape index and their FSI.