Relationship of black layer and milk line development on maize seed maturity

Abstract

The relationship of black layer and milk line development on maize seed maturity was evaluated under tropical conditions. Seed moisture (g.kg-1), standard germination - SG (7 days, 25°C), and vigor, using accelerated aging-AA (96 hours, 42°C and 100% of RH), cold test-CT only in 1991/92 (7 days at 10°C and 7 days at 25°C) and electrical conductivity-EC (four 50-seed samples, 24 hours imbibition at 25°C) and milk line and black layer formation (using a five-stage rating system) were determined at 3 to 4 days intervals, using two genotypes (hybrid CX 133 and variety IAC 100) during the crop seasons of 1990/91 and 1991/92. The results showed that physiological maturity was reached before stage 4, based on seed germination and vigor (AA and CT) values, which occurred before that stage and presented the lowest values of EC. On the other hand, moisture content levels of 300 to 350 g.kg-1 were reached only at stage 4. The milk line ratings proved useful in predicting physiological maturity as well as the harvest maturity.

Ideal seeds harvest moment of different maize hybrids

“…The endosperm solidifi cation process beginning at apex and ending at the base of each seed, being a characteristic easily detected in the fi eld and does not need special equipments. Many works have been conducted suggesting that the milk line can be used to identify the physiological maturity point and the ideal maize seed harvest moment (AFUAKWA & CROOKSTON, 1984;HUNTER et al, 1991, TEKRONY & HUNTER, 1995VIEIRA et al, 1995;FESSEL et al, 2001;FARIA et al, 2005;HENNING et al, 2011). Due to exposed, the developing of studies that compare different parameters to determine the proper time to maize seed harvest is important to avoid seed physiological quality losses.…”

Milk line as an indicator of the harvesting time of three hybrid seeds of corn (Zea mays L.)

“…The solidification of the endosperm is slower than black layer formation. All five solidification stages can be the endosperm in parallel with other characteristics mentioned earlier may lead to a more precise and suitable technique for identification of the best time for harvesting corn seeds in the field (Vieira et al, 1995).…”

“…Tekrony and Hunter (1995) observed maximum seed vigour around stage four of the black layer formation, and also stage four for milk line development, although maximum dry weight occurred at most at that stage. Vieira et al (1995) suggested that the milk line development would be a useful method to be used in the field. To these authors, this method allows subdividing the reproductive period of corn into five parts (stages), and then verifying the moment of maximum seed quality.…”

Évolution de la teneur en eau des grains et détermination de la maturité physiologique du maïs-grain (Zea mays L.)

“…Lorsque le grain de maı¨s parvient a`la maturite´physiologique, il y a alors formation d'une couche noire a`la base du grain au niveau de l'e´pi. Ce processus physiologique est commune´ment appele´le de´veloppement du point noir et il constitue aussi une autre me´thode efficace pour de´terminer la maturiteṕ hysiologique du maı¨s-grain (Daynard 1972;Muchow 1990;Hunter et al 1991;Nielsen et al 1994;TeKrony et Hunter 1995;Vieira et al 1995). La ligne de maturiteé t le de´veloppement du point noir sont e´troitement lie´s (Hunter et al 1991).…”

“…La ligne de maturiteé t le de´veloppement du point noir sont e´troitement lie´s (Hunter et al 1991). Hunter et al (1991) et Vieira et al (1995 ont de´montre´que l'utilisation de l'un ou l'autre de ces deux indicateurs semble aussi efficace pour de´terminer la maturite´physiologique du maı¨s-grain. Ces deux me´thodes exigent toutefois passablement d'e´nergie et de temps car il faut souvent re´aliser plus de trois observations pour parvenir a`de´terminer l'avancement de la maturite´physiologique a`l'aide de la ligne de maturite´ou pour parvenir a`de´terminer l'obtention de la maturite´physiologique graˆce a`l'apparition du point noir.…”