Abstract
Abstract: The objective of this work was to evaluate the physiological and production parameters of soybean (Glycine max) cultivars of determinate and indeterminate growth habits, in three levels of soil moisture. Three cultivars of determinate growth habit and three of indeterminate growth, at the beginning of the reproductive stage, were subjected to three levels of soil moisture: control, moisture at field capacity; moderated, 50% of the control level; and severe, 25% of the control level. Leaf gas exchange, xylem-water potential, chlorophyll content, chlorophyll a fluorescence, plant dry matter, and grain yield per plant were evaluated. The cultivars of indeterminate growth habit showed the greatest values for stomatal conductance and CO2 assimilation at the severe treatment, which led to the higher water consumption, in the morning, and to the lower xylem water potential, in the afternoon; however, there was no gain of soybean dry matter. In both growth types, the intensity and duration of the severe level of soil moisture were not able to change the chlorophyll fluorescence. Soybean cultivars of both growth habits, subjected to severe levels of soil moisture from flowering to pod insertion, show no significant change for dry matter and grain yield.
Highlights
Soybean [Glycine max (L.) Merrill] is considered one of the most important crops in the world, with a yield of 241.84 Tg (FAO, 2012)
In cultivars of determinate growth habit, the apical meristem stops the differentiation of new leaves after floral induction, while in cultivars of indeterminate growth habit, the differentiation of leaves occurs over some time after the floral induction (Tanaka & Shiraiwa, 2009)
The treatments consisted of six cultivars, three of determinate and three of indeterminate growth habits, and the following three levels of soil moisture: control, moisture at field capacity; moderate, 50% of water volume applied to the control; and severe, 25% of water volume applied to control
Summary
Soybean [Glycine max (L.) Merrill] is considered one of the most important crops in the world, with a yield of 241.84 Tg (FAO, 2012). Brazil is the second largest producer of soybean, with 97.18 Tg in the 2015/2016 harvest(IBGE, 2016). Soybean can be classified, according to its growth habit, as determinate or indeterminate. In cultivars of determinate growth habit, the apical meristem stops the differentiation of new leaves after floral induction, while in cultivars of indeterminate growth habit, the differentiation of leaves occurs over some time after the floral induction (Tanaka & Shiraiwa, 2009). The search for soybean cultivars with indeterminate growth significantly increased in Brazil (Perini et al, 2012). This is due to the necessity of earlier sowing dates to allow of both the corn sowing as
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