Inter-plant variability in maize crops grown under contrasting N×stand density combinations: Links between development, growth and kernel set
2012
Rossini, M.A. | Maddonni, G.A. | Otegui, M.E.
Genotypic differences in the response of maize kernel number per plant to ear growth rate around silking, caused by contrasting N availability, have been attributed to the effects of this element on reproductive efficiency (i.e. kernel set per unit of ear growth rate). The objective of current research was to assess if reduced reproductive efficiency of some genotypes under N stress is due to the effect of this nutrient on the number of completely developed florets per ear, the number of exposed silks per ear, and/or abortion of pollinated florets. Two field experiments were conducted with two hybrids previously characterized by their contrasting reproductive efficiency (high for AX820 and low for AX877) under N stress, two stand densities (9 and 12plm⁻²) and two levels of added N (0 and 200kgNha⁻¹). We established links among plant and ear growth rates, reproductive traits and kernel number per plant. Reduced reproductive efficiency (quantified as kernel number per plant per unit of spikelet growth rate around silking) of both hybrids under N deficiency was mainly due to an enhanced abortion of pollinated florets of the most suppressed plants of the stand (dominated individuals). This response did not appear to be the result of low spikelet growth rate around silking, but a direct control of N on sink capacity of fertilized ovaries for assimilates allocation.
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