Heterosis for Embryo Size and Source and Sink Components of Maize
1989
Djisbar, A. | Gardner, F. P.
Assimilate source and sink components controlled by genotype and environment determine grain yield of maize (Zea mays L.). Field experiments were conducted in 1986 and 1987 at Gainesville, FL (29° 38′ N) on a Lakeland sand (hyperthermicoated Thermic Quartzipsamment) to assess heterosis for vegetative and yield components. In order to equalize leaf area index and light interception, parent inbred lines B73, MO17, MS71, and VA22 were planted at normal plant populations density (PPD) of 55 000 and also at 110 000 plants ha⁻¹, while three F₁ hybrids from these inbreds were planted at 55000 and 27 500 PPD. In hybrid seeds, embryo size was associated with seed size. At common seed size (8 ram), lengths embryo and embryo axis of hybrids were greater than those of midparent and inbred line means, manifesting heterosis for embryo size. At common PPD, all biomass and grain yield source and sink components were significantly greater for hybrids than for inbreds. At common LAI and light interception achieved by doubling inbred PPD, hybrids produced significantly more biomass and kernel yield, kernel growth rate and weight, and grain-filling duration, but kernel number for hybrids and inbreds was similar at common LAI. We conclude that hybrids as compared with their parent inbreds express heterosis in source components, including embryo size, as well as sink components, all contributing to higher biomass and grain yields of maize. Contribution from the Inst. of food and Agric. Sci., Florida Agric. Exp. Stn. Journal Series no. 9190.
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