EVALUATION OF AGRONOMIC CHARACTERISTICS IN A RANDOM MATING 2-DWARF SORGHUM POPULATION UNDERGOING RECURRENT SELECTION FOR GRAIN YIELD (HERITABILITY, CORRELATION, S1 LINE)
Abstract
A genetically broad-based, 2-dwarf, sorghum population, Purdue Population 10R (PP10R), was used as a source population in recurrent selection for increased grain yield. PP10R is a random mating R-line population developed in 1975. The selection cycle yield trials evaluated 200 C(,0)-, 500 C(,1)-, and 275 C(,2)-S(,1) lines in randomized complete block designs with two replications in 1978, 1980, and 1982, respectively. The selection procedure, initiated by R. P. Cantrell, identified the 40 percent highest yielding S(,1) lines within days to bloom and plant height groupings. Following random mating of the bulked remnant seed of the selected S(,1) lines, the C(,1), C(,2), and C(,3) were produced. The selection procedure was an attempt to increase yield and maintain initial means and broad-based variability of other agronomic traits in PP10R. Traits observed were days to bloom, plant height, lodging, and yield. Cycles per se were evaluated in 1982 (C(,0)-C(,2)) and 1983-84 (C(,0)-C(,3)) in randomized complete block designs with 25 replications per year. Two different sets of S(,1) lines were evaluated in 1983 and 1984. In 1984, 100 S(,1) lines of each cycle (C(,0)-C(,3)) were evaluated in a randomized complete block design with two replications at two locations. The 1984 S(,1) line yield trial was more effective in detecting differences in cycle means than were the cycles per se yield trials. Regression analysis on the 1984 S(,1) line yield trial showed that yield increased linearly at a rate of 0.51 Mg ha('-1) per cycle. Undesirable shifts also occurred toward increased days to bloom, plant height, and lodging score. There was no indication that genetic variability was reduced for any of the agronomic traits studied. Estimates of genetic variance and narrow-sense heritability were high for all traits in all S(,1) line yield trials. Highly significant, positive genetic and phenotypic correlations were observed between all pairs of traits. The selection process eliminated short plants and the shift toward increased plant height was greater than expected. Covariate analysis, using days to bloom and plant height as covariates, was conducted to remove the effects of these correlated characters from the analysis of yield. The results indicate that the recurrent selection process has produced real changes in the frequencies of yield genes.
Degree
Ph.D.
Subject Area
Agronomy
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.