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Gibberellins and Heterosis in Maize: Quantitative Relationships
Author(s) -
Rood S. B.,
Buzzell R. I.,
Major D. J.,
Pharis R. P.
Publication year - 1990
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/cropsci1990.0011183x003000020008x
Subject(s) - heterosis , biology , shoot , gibberellin , seedling , gibberellic acid , germination , inbreeding depression , poaceae , apical dominance , horticulture , botany , agronomy , inbreeding , hybrid , population , demography , sociology
To investigate the possible relationship between gibberellins (GA) and heterosis, a diailel from four elite maize, Zea mays L., inbreds (A632, B73, CH807 [from Mo17], and CO109) was studied under controlled environment conditions. Heterosis for plant growth was substantial at 25/15 °C (day/night), as hybrid seedlings emerged more rapidly, were taller, had heavier shoots, and larger leaf areas than the parental inbreds. Gibberellic acid (GA 3 ) at 0.1, 0.5, or 1.0 mg per plant was pipetted into the leaf whorls of 14‐d‐old seedlings. The exogenous GA 3 promoted ligule and total height in all genotypes, but the inbreds were maximally influenced. Consequently, potence ratios, representing the overall degree of dominance, were reduced from an average of 7.7 to 1.7 following GA 3 application, indicating decreased heterosis. In an experiment at 15 °C, imbibition of seeds in GA 3 accelerated germination and seedling growth, particularly shoot elongation of the parental inbreds. Endogenous concentrations of GA 1 and GA 19 were determined by gas‐chromatography‐selected ion monitoring using [ 2 H]GAs as quantitive internal standards. Highly significant regressions of height, leaf area, relative growth rate, and height increment versus the log of GA concentration were observed. These results are consistent with the theory that GA are one factor involved in the regulation of heterosis of shoot growth in maize, a theory that suggests that a partial deficiency in endogenous GA in maize inbreds limits their growth, and is a contributing cause of inbreeding depression.