Seed Number of Hybrid Plants in Citrus, with Special Reference to Seed Number of Parents and Pollen Yield of Individuals

Abstract

In citrus, seedlessness is a desirable characteristic and. is one of the major breeding ob-jectives. One means of breeding new seedless or nearly seedless citrus cultivars is to produce male sterile hybrid seedlings. However, the relationship between male sterility and seed num-ber per fruit in hybrid plants has never been clear. Furthermore, the inheritance pattern for seed number has not been determined. Thus, the inheritance for seed number and the rela-tionship between seed number and pollen yield in 237 hybrid progenies resulting from 15 cross combinations were studied.
I. A positive correlation (r=0.772^**) was found between the mean seed number per fruit in the two parents and that in their progenies. A negative correlation (r = -0.687^**) was found between percentage of seedless hybrid progenies (mean seed number per fruit less than 1.0) and the mean seed number per fruit of the parents.
2. The mean seed number per fruit in progenies ranged 0.2 6.2, 1.421.8, and 4.518.6 in male sterile progenies, in progenies of poor yield of pollen, and in progenies of medium to good yield of pollen, respectively. In the same cross combination, the mean seed number per fruit was fewer in male sterile progenies than in male fertile progenies. The percentage of seedless hybrid progenies ranged 0.0100.0%, 0.075.0%, and 0.050.0% in male sterile progenies, in progenies of poor yield of pollen, and in progenies of medium to good yield of pollen, respectively. The percentage of seedless hybrid progenies was higher in male sterile progenies than in male fertile progenies in the same cross-combination except for one case.