Heterosis During the Early Phases of Growth in Intraspecific and Interspecific Crosses of Cotton
1973
Marani, A. | Avieli, E.
The performance of interspecific and intraspecific F₁ hybrids of Gossypium hirsutum and G. barbadense planted on two different dates was investigated. The interspecific crosses showed significant heterosis for percentage and time of germination, leaf number, and date of square formation when planted on the first planting date, and for plant height, LAI, and dry matter weight for both planting dates. The G. barbadense intraspecific cross exhibited a higher degree of heterosis than the G. hirsutum one for germination and dry matter weight when planted on the first planting date. The traits exhibiting significant estimates of heterosis for early planting, but not for late planting, were those associated with the early phases of plant growth. The differences stemming from planting dates were probably due to the low temperature that prevailed after the first planting, since the temperature after the second planting was close to the optimum. We concluded that F₁ hybrids have greater phenotypic stability than their parents when confronted with varying temperature conditions. This condition probably results from their heterosis for seedling growth rate under suboptimal temperature regimes.
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