Correlated Responses in Ear and Plant Traits in Maize Synthetics Selected for R-nj Color Expression
Maize (Zea mays L.) cobs contain vascular tissue that supports grain yield. We wanted to learn if rate of grain filling or carbohydrate source (leaf area) are related to early ear and cob development. studied substrains (known to differ in grain-filling rates) derived from two early- (NDSF, NDSM), two intermediate- (NDSC, NDSD), one late-maturing (NDSE) synthetics. These five synthetics were each mass selected for four cycles for high (HC), random (RC), and (LC) R-nj color expression. Plants of each of the 15 substrains were grown in the field at 58 000 plants ha−1 in Fargo and Casselton, ND, in 1993 and 1994. We measured leaf lengths, widths, and numbers to estimate leaf areas per plant. We monitored early ear development for two maturity groups within each substrain by measuring ear lengths, widths, and wet weights at 7 and 14 d after silking. Maturity differences among synthetics explained more than 80% of the variation in leaf length and width, leaf area per plant, and ear length at 7 d. The HC, compared with LC, selections produced 3% longer and 6% heavier ears at 7 d, had 5% more and 3% wider leaves, and had 4% larger leaf areas per plant. The earlier ear development of HC strains may contribute to higher kernel growth rates. Due to larger leaf areas per plant, HC strains also may produce more photosynthate for translocation into the developing kernels. Selecting for improved vascular systems may be useful.
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