Emisión de estigmas en maíz: efectos del genotipo y el nitrógeno.

ROSSINI, M.A.; D'ANDREA, K.E.; OTEGUI, M.E.

Rosario, Santa Fe, Argentina

Congreso; VIII Congreso Nacional de Maíz.; 2005

A.I.A.N.B.A.

The main determinant of maize grain yield is the number of harvestable grains at maturity. This number depends upon final kernel set at the end of the critical period around flowering, which relies strongly on the pollination/fertilization process among ovaries along the ear. This process is under genetic and environmental control, and the effect of abiotic stresses have been documented for the anthesis-silking interval (ASI) but not for silking dynamics within a ear. The objective of this research was to evaluate the effect of nitrogen (N) availability on flowering dynamics (i.e. anthesis and silking dates), silk emission from apical ears (i.e. silks exposed per plant), and silks exposed per unit land area of four inbred lines and four derived single-cross hybrids. Genotypes (G) were cropped in the field (33º56’ S, 60º33’ W) at two levels of N availability (N0: low level; N1: high level) in a split-plot design with G in the main plots. Flowering dynamics and final kernel number were measured on the same tagged plants, while silk emission was computed on a different set of plants. Genotypes were significant different in all traits related to flowering dynamics. Nitrogen deficit significant increased ASI and delayed the time to first silking and 50% of anthesis and silking. It was possible to establish strong relationships between the average values of the parents and their derived hybrids for the integral of receptive silks number and between the receptive silks number and the maximum number of flowers per ear. The latter variables explained grain number of the hybrids but not of the inbred lines. This work shows, for the first time, information related to flowering dynamics and silks emergence of inbred lines and derived hybrids growing under contrasting N conditions.