Abstract
Seven interspecific peanut (Arachis hypogaea L.) lines and Southern Runner were crossed in a half-diallel. The F, , F2, and F, progenies were evaluated for early leafspot reaction and yield. The objectives of the study were: 1) to determine the predictability in F, and F2 generations of crosses most likely to give the greatest expression of early leafspot resistance and yield; 2) to assess the genetic response due to early generation selection; 3) to compare alternative methods of selection for early leafspot resistance; and 4) to assess the use of molecular markers (RAPD) for selection for leafspot resistance. Disease assessment was made using the Florida leafspot rating scale at I 10 and 130 days after planting, and determinations were made for lesion diameter, amount of sporulation, and latent period in both the field and laboratory. Genetic analysis was performed using the Griffing method 2 model 1. Significant differences existed among crosses for the visual leafspot rating, latent period, and amount of sporulation in the F2 generation (P = 0.05). Pod yield, based on individual plants, differed significantly among the F2 crosses, but not in the F, (P = 0.05). Little heterosis was found among these F, crosses. Performance of the F , was not reflected in the F2, as rank correlation between the two populations for pod yield was low (r = 0.32) and not significant (P = 0.05). Combining ability effects (both general and specific) were significant for yield and disease parameters in the F2 and F3 generations. In a preliminary study, 60 primers out of 200 tested yielded 103 bands of size generally less than 1,900 bp. Analysis of the banding pattern revealed a higher incidence of polymorphism between A. hypogaea and A. cardenasii Krapov and W.C. Gregory and A. diogoi Hoehne respectively, than between A. hypogaea and the advanced interspecific lines. The results indicated that DNA segments were successfully transferred from the wild species to the cultivated A. hypogaea and that genetic diversity in peanut can be assessed using RAPD markers. Evidence of association between any of these RAPD markers to early leafspot resistance or any trait of interest was not established in this study.
Ouedraogo, Mahama (1995). Yield and leafspot response of interspecific peanut crosses in early generation tests. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -1560140.