Abstract
Soybean [Glycine max (L.) Merr.] growth rate and grain yield are modified by the interception and solar radiation use efficiency. Thus, it is desirable that the most of plant photosynthetic structures intercepting solar radiation in order to have increment in carbon fixation and reflection on growth and yield. The goal of this study was to assess if soybean cultivars differ in grain yield in relation to solar radiation interception. Four soybean cultivars were evaluated at stages V6, V9, R2, R4, R6 and R8. To determine the photosynthetically active radiation interception by the canopy, the plants were divided into two parts (upper and lower strata). For grain yield components, the plants were divided into three parts (upper, middle and lower thirds). Of the photosynthetically active radiation intercepted by the vegetative canopy at the reproductive stages, the maximum observed intercept was 5.2% in the lower stratum of the plants. The number of infertile nodes increased in the lower third of plants due to low interception of solar radiation in this plant region. Thus, the soybean cultivars more efficient in intercepting photosynthetically active radiation inside the vegetative canopy showed higher grain yields.
Highlights
Plant growth depends on carbon assimilation, which is directly related to intercepted photosynthetically active radiation (IPAR)
Plant growth rates can be obtained by estimating solar radiation use efficiency (RUE), which is defined by the ratio between biomass increase and radiation intercepted by the plant canopy [2] [3]
Given the short stature of plants at V6 stage, solar radiation availability was evaluated at above canopy and at ground level, to give the total amount intercepted by the canopy (Figure 1)
Summary
Plant growth depends on carbon assimilation, which is directly related to intercepted photosynthetically active radiation (IPAR). Part of photosynthetically active radiation (PAR) is absorbed and used in photosynthesis, and the rest is lost. Plant growth rates can be obtained by estimating solar radiation use efficiency (RUE), which is defined by the ratio between biomass increase and radiation intercepted by the plant canopy [2] [3]. Radiation interception efficiency (RIE), the fraction of light intercepted by the plants, can be high or low [4], and depends on the leaf area index and morphological characteristics [5]. The shading decreases total soluble sugar concentration in soybean leaves, causing reduced numbers of pods; reduction of 42.5% in the number of pods is observed for plants shaded during the cycle, while the increase of light availability brought about increases of 59.5% in the number of pods [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
