Fruit yield and yield component means and correlations of four slicing cucumber populations improved through six to ten cycles of recurrent selection.

摘要

Increased fruit yield in slicing cucumber has been difficult to achieve since yield is quantitatively inherited with low heritability. During 1981-93, 4 slicing cucumber populations (NCWBS, NCMBS, NCES1 and NCBA1) differing in genetic diversity (wide, medium, elite and Beit Alpha, respectively) were advanced through 6-10 cycles of modified half-sib recurrent selection. The objectives were to determine: (1) fruit yield and yield component means; (2) correlations between yield and its components; and(3) the change in means and correlations with selection for improved yield in the 4 populations. In 1994 and 1995, 4 families were randomly selected from 3 cycles (early, intermediate and late) from each population and were self-pollinated. In 1995 and1996, 30 plants from each S1 family were evaluated in 3.1 m long plots in spring and summer in Clinton, North Carolina, USA. Plants were harvested and data were collected on the number of branches/plant and nodes/branch, proportion of pistillate nodes, fruit set and shape, and total, early and marketable yield. When averaged over all populations, seasons and years, fruit yield and quality increased with selection, while yield components remained unchanged with selection. Fruit yield and components differed between populations, seasons and years. Most correlations between yield components and between yield components and fruit yield were weak, and strong correlations varied between populations, seasons and yield components. Indirect selection of the proportion of pistillate nodes has potential for improving yield for certain population-season combinations. Selection weakened many strong correlations between yield components and between yield and components. Changes in correlations often did not correspond with changes in trait means. Based on this research, selection for yield components would not be advantageous for improving fruit yield in all slicing cucumber populations. It is suggested that additional yield components, yield component heritability, and better component selection methods need to be determined before component selection can be used to improve fruit yield.