ABSTRACT
The aim of this study was to identify plastochron phases in soybean cultivars with determinate and indeterminate growth habits. Experiments were conducted from 2010/2011 to 2022/2023 at four locations in Rio Grande do Sul state (RS), Brazil, using 25 soybean cultivars with determinate (6) and indeterminate (19) growth habits. This study divided the plastochron into phases during the soybean node emission stage. In irrigated cultivars with a determinate growth habit, the plastochron has an early and late phase of 59.7 and 65.7 °C day node-1, respectively. In rainfed (non-irrigated) environments, there is no difference between the early and late plastochron phases. The early and late plastochrons of irrigated cultivars with an indeterminate growth habit are 64.1 °C day node-1, while the intermediate phase is 58.5 °C day node-1. In rainfed environments, the average value of the early and intermediate phases is 60.6 °C day node-1, with a late plastochron of 79.4 °C day node-1. Dividing the plastochron into phases during node emission, as proposed in this study, improves understanding of vegetative development in soybean cultivars with determinate and indeterminate growth habits and establishes ecophysiological foundations for chronological function construction.
Key words:
agricultural modeling; node emission; plant development
HIGHLIGHTS:
This study identifies plastochron phases in soybean cultivars based on growth habit and water regime.
The plastochron varies according to the growth habit rather than the maturity group of soybean cultivars.
Determinate and indeterminate soybean cultivars have different plastochrons under different water regimes.
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Symbols and colors indicate the different stages of plastochron calculation. Arrows represent the reproductive stages R1 (green), R3 (Yellow) and R5 (Red) (
The solid line indicates the median and X the mean. Different colors and letters are significant according to Dunn’s Post Hoc test at 0.05 probability, by phase, with the p-value shown in the figure
The solid line indicates the median and X the mean. The p-values for Dunn’s Post Hoc test at 0.05 probability are shown the figure. Different letters indicate differences between plastochron phases
Locations: SM - Santa Maria and ITA - Itaqui. The blue and orange bars and different letters differ significantly according to Dunn’s Post Hoc test at 0.05 probability, by phase, with the p-value shown in the figure. The gray bars indicate no significant difference between the blue and orange bars within each plastochron phase
The blue and orange bars and different letters differ according to Dunn’s Post Hoc test at 0.05 probability, by phase, with the p-value and coefficient of variation (CV) shown in the figure. ns: not significant according to Dunn’s Post Hoc test at 0.05 probability. The gray bars (ab) indicate no difference between the blue and orange bars within each plastochron phase
The blue and orange bars and different letters differ according to Dunn’s Post Hoc test at 0.05 probability, by phase, with the p-value and coefficient of variation (CV) shown in the figure. ns: not significant according to Dunn’s Post Hoc test at 0.05 probability. The gray bars (ab) indicate no difference between the blue and orange bars within each plastochron phase