Influência do tipo de crescimento, época e densidade de semeadura em caracteres morfoagronômicos de cultivares de soja
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2015-02-20
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Universidade Federal de Goiás
Resumo
In Brazil determinate stem termination soybean plants with long juvenile
period are traditionally grown. In the last five years, indeterminate and semideterminate
soybean plants, especially early maturity varieties in early sowing dates, were adopted in
different latitudes, aiming to cultivate a second crop. When grown on different densities,
soybean plants have compensation mechanisms on stem height, number of branches and
pods per plant. The objectives of this study were: i) evaluate the effect of sowing date and
plant density on soybean morphoagronomic traits of soybean cultivars with different stem
termination; ii) correlate grain yield with morphoagronomic traits in each type of growth
and sowing date, and yield components with each other in each type of growth and density;
iii) perform discrimination among types of growth in soybean cultivars, identifying sowing
conditions that cause changes in the response of morphological traits with ambiguity in the
phenotypic expression of growth types. Three experiments were: early October (10.02.13),
mid November (11.18.13) and early January (08.01.14) in the experimental area of
Embrapa Arroz e Feijão in Santo Antonio de Goiás, Brazil (16°29’S, 49°17’W), at
2013/2014 season. Trials were performed in a randomized complete block design with
three replications. Treatments included two factors, stem termination and plant population
density. Four cultivars were used for each stem termination; determined, semideterminate
and indeterminate. The plant densities corresponded to 50%, 100% and 150% of
commercial recommendation to each variety. The traits assessed were number of days to
flowering, number of days to maturity, plant height at flowering, height of first pod, plant
height at maturity, growth percentage after flowering, number of nodes on main stem,
number of branches on main stem, number of pods per node, number of pods per plant,
number of grains per pod, number of grains per plant, one hundred grain weight and yield.
For most assessed traits, soybean plants of each type of growth respond differently to
changes on sowing date and plant density. Only in November sowing, the determinate type
of growth showed lower yield comparing to the others types. The increase in plant density
causes higher plants on flowering and maturity, less number of nodes and branches in the
main stem, and lower average on yield components. Regardless of the type of growth, in
the first sowing date yield showed greater correlation, positive, with number of seeds per
pod; however, in other sowing dates this correlation occurred with one hundred grain
weight. Plant density has more influence on the associations among yield components in
the determinate and indeterminate growth types, than in the semideterminate type. The
greatest variation in morphoagronomic traits was observed between determinate stem
termination and the other types of growth. Most change on classification of type of growth
(ambiguity) occurs in late sowing and high plant density. The percentages of growth after
flowering and main stem node and branches numbers are the most important traits on type of growth discrimination.
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Citação
VAZ BISNETA, M. Influência do tipo de crescimento, época e densidade de semeadura em caracteres morfoagronômicos de cultivares de soja. 2015. 76 f. Dissertação (Mestrado em Genetica e Melhoramento de Plantas) - Universidade Federal de Goiás,Goiânia, 2015.