Estimates of the combining abilities for pink root resistance and agronomic traits in onions

Aimed at estimating the combining abilities for pink root resistance and agronomic traits in onion (Allium cepa L.), the present study was carried out by using partial diallel scheme. Two partially endogamic inbred line groups were used as parents. Group I consisted of five male-sterile female inbred lines, originated from a Brazilian Tropical Onion Population, selected for sowing during the summer. Group II consisted of ten male inbred lines, most of which originated from Crioula onion populations, obtained by successive self-pollination and kept by mass selection within lines. The following traits were evaluated: pink root resistance using a score scale from 1 to 5, leaf vigor, leaf architecture, number of leaves, plant height (cm), total number of bulbs and total weight of bulbs (kg). Experimental design was in randomized blocks with three replicates. There were additive effects on pink root resistance and considerable non-additive effects for some combinations; the same genetic behavior was found for the other agronomic traits of interest. Thus, intrapopulation selection can be done with the inbred lines used in the current study and hybrids of high level of pink root resistance, as well as good agronomic traits, can be obtained.