[en] Three hybrid peanut populations involving a single pair of high yielding parents were developed to determine the effects of irradiation prior to and after hybridization on the response to selection for fruit yield. The control-hybrid population was produced by making reciprocal crosses between the two parents. The pre-hybrid-irradiated population was initiated by making reciprocal crosses between the M₁ plants of the two parents irradiated as seeds. The post-hybrid-irradiated population was developed by irradiating the mature F₁ embryos of crosses between the same parents. Each of the three original populations consisted of 55 F₁ plants. Ten F₂ plants were grown from each F₁ and one F₃ plant from each F₂ was used to initiate the yield tests. Selection for increased yield was practiced systematically and uniformly in each population over the F₃ to F₅ generations until the number of lines derived from single F₁ plants was reduced to five and the number of sublines descended from particular F₂ plants to three per line for yield trials in the F₆ generation. The mean yields of the F₁ derived lines of the irradiated populations were considerably below that of the control hybrid population when selection began but they reached 99% of the control mean in the F₆ generation. Selection gains in the irradiated populations appeared to result from the removal of inferior yielding sublines since greatest progress was made by raising the lower extremities of mean F₂ derived subline ranges rather than by extending the upper extremities of the ranges. The three highest yielding lines in the F6 generation occurred in the irradiated populations while the three highest yielding sublines were found in the hybrid-control population. No incidental association between size and yield of fruit was noted and a wide range of fruit sizes was found among the high yielding lines and sublines in all populations. (author)

[en] Three separate experiments were conducted with cultivated peanuts to (a) study the effect of four controlled temperatures on the expression of seven radiation-induced macromutants and the mother line; (b) determine the responses of normal appearing F₁ hybrids involving four macromutants to three controlled temperature regimes and (c) evaluate the same macromutant, parental and F₁ hybrid populations (described in b) when grown for a full season under field conditions. Macromutant plant weights and flower productions were generally lower than that of the mother line in all three experiments. The macromutants also tended to flower later than the mother line. The leaflet expression of two of the macromutants was drastically influenced by changes in temperature. Lupinus reached maximum leaflet curvature when grown at 34/30⁰C but appeared near normal when grown at 22/18⁰C. The reverse was true for the macromutant Recurved. The macromutant Flop contained maximum percentages of nitrogen and phosphorus in its vegetative parts when grown at the highest temperature (34/30⁰C). All other mutants and the mother line had highest proportions of these nutrients when grown at the lowest temperature regime (22/18⁰C). Expressions of heterosis were maximized when hybrids of macromutant parentage were grown at sub-optimal temperatures. General combining ability estimates were higher than specific combining ability estimates with the macromutant Hedera (a dwarf type) making the greatest contribution to the general combining ability effects for peg (fruit-bearing structure) production and pegging efficiency. The same macromutant was found to make substantial contributions to general combining ability effects for fruit and seed weight when hybrids were grown under field conditions. (author)

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