Effects of Environment upon Ovule Abortion in Interspecific F1 Hybrids and Single Species Cultivars of Cotton1
- R. G. Percy2
High ovule abortion rates (mote production) observed in Gossypium hirsutum L. ✕ G. barbadense L. interspecific F1 hybrids (ISH) have generally been attributed to the presence of genetic incompatibilities between the two parent species. Other causes of mote production within G. hirsutum and G. barbadense cottons are adverse environmental factors. This study was conducted to determine to what degree environment contributes to the large mote numbers observed in ISH, to determine if ovule abortion in ISH is more reactive to environment than in single species cultivars, and to determine if parental combinations might influence hybrid sensitivity to mote production. Data were collected from four ISH and their four parent strains under normal and reduced irrigation regimes at two locations in 1983 and under normal and reduced irrigation regimes on three dates at one location in 1984. The soil at the Maricopa, AZ, location used in both years was a Mohall clay loam, a member of the fineloamy, mixed, hyperthermic Typic Haplargids. The Safford, AZ, location used in 1983 possessed a fine loamy, mixed, thermic Typic Torrifluvent soil type. Measurements made included: potential seed number (determined to be the number of seed plus motes per locule), ovule abortion rate (expressed as the percent of the potential seed number per locule which were motes), and locule weight (grams seed cotton per locule). Significant generation and species differences were noted for all traits measured in both years. Significant generation ✕ environment interactions were obtained for ovule abortion rates in 1983 and for ovule abortion rates, potential seed number, and locule weight in 1984. Interspecific F, populations were more reactive to the environment than their parent lines. There appeared to be a species contribution to the hybrids' environmental responses, but little evidence of a cultivar-within-species contribution. Little or no environmental response variation was observed among the ISH populations for the traits measured. An environmental sensitivity for ovule abortion within ISH cottons which appears to be independent of parental contribution was documented.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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