Abstract
The study of soybean (Glycine max) biometry and phenology can detect characteristics that interfere with yield, and quantitative plant development may vary according to the interaction between the genotype and the environment, and in different phenological development stages of the plant. This study evaluated the quantitative changes and phenological development caused by sowing date and their relation to grain yield of four contrasting soybean cultivars. The experimental design was a split plot with three replications, being the sowing date allocated to plots and the cultivars to subplot. The height of plants, diameter and number of nodes of the main stem, number of the branches, and leaf area index (LAI) were determined at four growth stages: V4, V9, R2 and R5.3, and the number and dry matter (DM) of the nodules at R5.3 growth stage. There was a reduction of growth in all cultivars with delayed sowing dates; however, the cultivar of determined growth habit showed to be less responsive to different sowing dates than the other cultivars. The DM of nodules was higher when plants were sown in October, and the cultivar with larger LAI obtained more DM of nodules than the others cultivars. The definition of the final quantitative characteristic of the plants occurred after the growth stage V9, and the LAI was the character at R5.3 with highest correlation with grain yield. Key words: Branches, Glycine max, leaf area index, nodulation, plants height.
Highlights
INTRODUCTIONA plant phenological study is a tool that allows us to identify plant quantitative changes at determined growth stages associated with a series of necessities of the plants, which, if attended, will enable normal crop development and high yields (Cruz et al., 2010)
A plant phenological study is a tool that allows us to identify plant quantitative changes at determined growth stages associated with a series of necessities of the plants, which, if attended, will enable normal crop development and high yields (Cruz et al., 2010).The soybean (Glycine max) is a plant that is highly dependent on the interaction between the genotype and the environment; it can change its cycle and its vegetative development depending on this interaction
These studies can result in information that leads to an understanding of how the cultivars at different sowing dates result in a lower negative influence of the environment, and how quantitative plant characteristics could interfere with grain yield
Summary
A plant phenological study is a tool that allows us to identify plant quantitative changes at determined growth stages associated with a series of necessities of the plants, which, if attended, will enable normal crop development and high yields (Cruz et al., 2010). Unfavorable temperatures out of the range between 24 and 34°C (Egli and Bruening, 2000), low solar radiation (Setiyono et al, 2010) and the short length of the photoperiod, which may affect the flowering (Han et al., 2006), are the abiotic factors commonly found at late sowing dates These factors may interact with the genotype of the soybean plants, affecting the growth and development of this crop. It is important to study the growth of soybean cultivars with contrasting responses to the environment conducted under different environmental conditions These studies can result in information that leads to an understanding of how the cultivars at different sowing dates result in a lower negative influence of the environment, and how quantitative plant characteristics could interfere with grain yield. Correlation was performed between the quantitative plant characters and the final grain yield, and the correlation significance was evaluated by Student’s t-test
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