Synchronous Pollination Within and Between Ears Improves Kernel Set in Maize

CÁRCOVA, J.; URIBELARREA, M.; BORRÁS, L.; OTEGUI, M.E.; WESTGATE, M.E.

CROP SCIENCE

Crop Science Society of America

Lugar: Baltimore; Año: 2000 vol. 40 p. 1056 - 1061

0011-183X

In maize (Zea mays L.), abortion of late-fertilized ovaries is an important source of reductions in kernel set. The objective of this work was to analyze changes in kernel set in natural- and hand-pollinated ears of four hybrids of contrasting prolificacy (ears plant-1), grown in the field at low (2.5 and 3 plants m-2) and high (7.5 and 9 plants m-2) plant populations, with no water or nutrient stress. Plants were subjected to natural and hand pollination in order to modify the number of simultaneously pollinated silks. Silk emergence was monitored after silking and kernel set per pollinated silk (SFI= spikelet fertility index) was calculated. For most hybrids, increased plant population promoted a delay in silk appearance, but most silks were exposed on day 5 after silking (5 DAS). Synchronous pollination of all exposed silks on 5 DAS improved kernel number (KN) and SFI. Increments in KN were related to the subapical ear at low plant populations and to the apical ear at high plant populations, and ranged between (i) 10 and 30% for low populations, and (ii) 8 and 31 % for high populations, depending upon hybrids. Deferred fertilization of early-silking ovaries allowed some of the later-appearing ones to compensate for their ontogenic delay and set kernels. Hence, assimilate availability per fertile spikelet seems not to be the only factor controlling kernel set when water and nutrients are not limiting growth. Silk emergence rate, which affects pollination dynamics, may explain part of the genotypic differences in KN and SFI.