Effects of Natural Selection in Advanced Generations of Barley Composite Cross II¹

Abstract

Barley (Hordeum vulgare L.) composite‐cross II (CCII) populations that had been grown over a long period in three environments in California and Montana were tested in 16 Montana and three California environments. The populations included F15 to F37 generations of CCII previously grown with natural selection at Moccasin and Bozeman, Mont. and Davis, Calif., local check cultivars, and a mixture of the original parents of CCII (P Mix). The CCII populations were generally higher yielding than the P mix which is an indication of improvement due to natural selection. Little or no differences were found among the various CCII populations which had been grown in the widely different environments of Montana and California. Populations developed at one site were not higher yielding at that site than populations developed at another site in seven of eight cases. Far superior progress has been made by conventional breeding, for example ‘Briggs’ and ‘Atlas 68’ yielded significantly more than the best populations under the disease and high‐yield conditions at Davis. The CCII populations tested in diverse environments in Montana also yielded less than local cultivars. When tested at Moccasin and Bozeman, however, where they had a developmental history of 12 to 24 years, the best CCII populations were equal in yield to the best cultivars. Yield stability of CCII populations in the 16 diverse environments was inconsistent; however, the population grown at Moccasin for 24 generations was more stable than ‘Unitan’ and ‘Ingrid,’ while eight populations were less stable than ‘Dekap’. The Davis‐developed material had higher kernel weight and percentage of plump kernels than the Montana‐developed populations. Test weight was highest in the Moccasin‐developed populations. There were no differences among the CCII populations for heading date, plant height, grain protein, and lodging resistance.

Comparative analysis of performance and stability among composite cross populations, variety mixtures and pure lines of winter wheat in organic and conventional cropping systems

“…Early research on mixtures and CCPs has occasionally found inconclusive results with regard to the effects of genetic diversity on yield stability (Hockett et al, 1983), or even lower yield stability in mixtures than in monocultures (Clay and Allard, 1969). However, most studies found a yield-stabilizing effect of cultivar mixtures (Frey and Maldonado, 1967;Wolfe, 1985;Dubin and Wolfe, 1994;Mundt, 2002) and composite cross populations (Soliman and Allard, 1991) in cereal crops, in agreement with our results.…”

Dynamic conservation of variability: responses of wheat populations to different selective forces including powdery mildew

“…Genetic drift could not be ruled out to explain this, but such a rapid differentiation would only be expected if the number of reproductive individuals was small, which was not the case with the experimental protocols used (Pontis, 1992 (David, 1992 (Hockett et al, 1983;Allard, 1988 (David, 1992 (Austin et al, 1989). This evolution occurred because of the decrease in the length of stems.…”

Conservation of powdery mildew resistance genes in three composite cross populations of barley

“…All three populations were developed at Davis, California, and grown each year under normal agricultural conditions. In Montana, the same populations were grown intermittently (HOCKETT et al, 1983). CC11 (C.I.…”