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Corn Seed Maturity Indicators and their Relationship to Uptake of Carbon‐14 Assimilate
Author(s) -
Hunter J. L.,
TeKrony D. M.,
Miles D. F.,
Egli D. B.
Publication year - 1991
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1991.0011183x003100050045x
Subject(s) - biology , hybrid , maturity (psychological) , zea mays , agronomy , horticulture , dry weight , zoology , botany , psychology , developmental psychology
Various maturity rating systems have been proposed to evaluate seed development in corn ( Zea mays L.). The objective of this research was to determine the relationship of seed assimilate uptake and dry weigh to three indicators of physiological maturity: moisture concentration, black layer, and milk line development. Assimilate movement into the seed was determined by exposing the leaf subtending the ear to 14 CO 2 at regular intervals during seed development and measuring the 14 C 24 h later in F 2 seed of B73 ✕ Mo17 (1984, 1985) and the stay‐green hybrids FS854 and Pioneer Brand 3358 (1985). In 1986 and 1987, plants of the same F 2 hybrids and the inbreds B73 and Mo17 and their F 1 cross (B73 ✕ Mo17) were defoliated at ≈20 d after pollination and seed development was compared to that of undefoliated plants. Seed dry weight, moisture concentration, and milk line and black layer development (using a five‐stage rating system) were determined at 3‐ to 5‐d intervals. Uptake of 14 C‐assimilate by seed and cob tissue decreased sharply near the end of the linear phase of seed dry weight accumulation when the milk line and black layer ratings were at Stage 3 (mid‐milk line) greater. Near Stage 4 of both black layer and milk line development, 14 C in the seed had fallen to the lowest levels, maximum seed weight had been reached, and the seed were physiologically mature. Both black layer and milk line followed consistent rends throughout seed development for all hybrids (including the stay‐green genotypes), defoliation treatments, and years. Seed moisture during seed development was highly correlated with both black layer and milk line, but the concentration at black layer Stage 4 was more variable (293–415 g kg −1 ) across genotypes and years. The data suggest that Stage 4 of both black layer and milk line development represents a useful and reliable indicator of physiological maturity.