Showing papers on "Heterosis published in 1969"

A Molecular Basis for Heterosis

Abstract: Alcohol dehydrogenase allodimers composed of an unstable active subunit and a stable but inactive subunit are both active and stable The implication of this finding for the problem of heterosis is discussed

HETEROSIS IN VEGETATIVE GROWTH OF THE RICE PLANT : Genetical Studies on Rice Plant, XXXIX

Abstract: Heterosis originally occurs in plant weight at early stage of growth and is transmitted to other vegetative characters through the path of developmental correlation of characters. High yield of hybrids may be expected at non-economical with spacing or in genetic mixture, but it may not be expected in pure stands densely planted.

Inbreeding and heterosis in autotetraploid alfalfa. i. fertility

Abstract: Certain aspects in the quantitative genetics of autotetraploid populations have been developed into a deterministic model. The use of two mating systems, inbreeding and hybridization, on the fertility of two alfalfa clones gave results which were in close agreement with the proposed model. The interactions between more than two alleles, whether identical or not, were important in the expression of heterosis. Performance of hybrids became weaker and weaker as the parents were more and more inbred. It was possible to evaluate the influence of the various genotypic structures on seed setting.

Agronomic Performance, Hydrocyanic Acid Potential (HCN-p) and Heterosis in Forage Sorghum Hybrids

Abstract: In 1981 field studies at the lsabela Experiment Farm in northwestern Puerto Rico, we evaluated agronomic performance, hydrocyanic acid potential (HCNp) and heterosis in forage sorghum hybrids ( Sorghum bicolor (L.) Moench). Three cuttings were made at 60-day interval. The combined analyses showed significant differences in yields of green forage (GF), dry forage (OF) and crude protein (CP); contents of dry matter (OM) and crude protein; tillers/plant; height; leaf area; and HCN-p at 45 days. Harvests were not a significant source of variation in leaf/stem ratio or in HCN-p at 60 days. The F 1 hybrids of CK-60 x Fa357, CK-60 x Common and CK-60 x Lahoma produced the highest OF and CP yields across the three harvests. The OF and CP yields of these top sorghum-sudangrass hybrids-about 20 and 2 metric tons, respectively in 180 days-and their relatively low HCN-p values, establish these genotypes among the most promising forage material for use under irrigation. The HCN-p values of all genotypes were lower at the 60-day harvest than at the 45-day sample. There were some instances of HCN-p value exceeding the "threshold of danger" of 200 p/m. Midparent heterosis was manifested for GF, OF and CP yields, height, tillers/plant and leaf area, but not for OF and CP content. High parent heterosis was less than midparent heterosis for most traits studied and was not observed for OM and CP content or for tillers/plant. The F 1 hybrid of CK-60 x Common exhibited the greatest heterosis, producing 146 and 125% more DF than the midparent and high parent, respectively. Fa357 was superior to all other lines in having the lowest HCN-p among the male parents at 60 days. Lahoma had the highest yield potential of the male parent lines and an intermediate level of HCN-p compared to the other lines.

Heterosis in diallel crosses among six varieties of hard red spring wheat

Abstract: Diallel crosses were made among six varieties of hard red spring wheat that differed considerably in yield and other characteristics. The F1 hybrids were tested at two seeding rates and the F2, hybrids at one. Heterosis was not great in either generation and no cross appeared to be promising. General combining ability was much more important than specific combining ability and parental yields gave reasonable predictions of hybrid yields. Yields of hybrids at the two seeding rates were closely correlated.

Heterosis and combining ability in hybrids of Avena sativa L. and A. byzantina C. Koch.

Abstract: SUMMARY Three varieties of Avena byzantina C. Koch., Sierra, Avon and Anita, originating respectively in California, Australia and South Africa, together with the Dutch variety Condor (A. sativa L.) were used as ‘subject’ varieties in crosses with a range of nine tester varieties of mainly north-west European origin. The results of a yield trial of spaced F1 transplants and a drilled F2 trial are presented. In the F1 trial there was marked heterosis for grain yield, the thirty-six crosses yielding, on average, 109 % of the higher yielding parent, with individual cross values ranging from 68 to 139%. Heterosis was more marked in sativa × byzantina crosses than in sativa × sativa crosses and the variety Sierra showed particularly high general combining ability. In the F2 trial, heterosis was considerably reduced and the thirty-six crosses yielded, on average, only 96% of the higher yielding parent. In some F1 crosses, heterosis for grain yield was accompanied by transgression of the higher yielding parent in number of panicles per unit area. The number of grains per panicle was positively correlated with grain yield in the F2 trial but no heterosis was observed for this component. Grain size was negatively correlated with yield in the F2 trial and heterosis for this component was observed in a few crosses in which yield heterosis occurred. Straw height was positively correlated with grain yield in the F1 trial but negatively correlated in the F2 trial. Crosses showing heterosis for yield exceeded the mid-parent but not the taller parent in straw height. The ratio of grain yield to straw yield was higher for the progenies of the byzantina varieties Sierra and Avon than for the progenies of the sativa subject Condor. Grain yield was positively correlated with number of days to 50% panicle emergence in both trials. It is concluded that the A. byzantina varieties Sierra and Avon could, with advantage, be used for hybridization with adapted genotypes of A. sativa, thereby enlarging the gene pool available to oat breeders in north-west Europe.

Gene Effects and Heterosis in Pearl Millet

Abstract: Using P1 P2, F1 F2, B1 and B2 generations of a cross between two inbred lines, gene effects were calculated for 15 grain- and fodder-yield contributing characters of pearl millet (Pennisetum typhoides S. and H.). The observed heterosis was interpreted in terms of these gene effects.

STUDIES ON FORAGE SORGHUM BREEDING. : V Heterosis and Combining Ability in F1 Hybrids between Male-sterile Line and Other Morphological Groups.

Abstract: This investigation was conducted for confirming the superiority of hegari group and/ or sudangrass group as pollen parents and clarifying the effects of forage characteristics of male-sterile line on forage yield in hybrid forage sorghum. Hegari group and sudangrass group were proved to be the excellent pollen parents by means of their greater heterosis and general combining ability in F1's. It was also suggested that forage characteristics, especially stem length, of male-sterile line did not affect on yield and its components in hybrid forage sorghum.