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Vertical leaves and sunlight interception: biomass conversion efficiency

Grant number: 14/11151-2
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): September 01, 2014
Effective date (End): January 31, 2016
Field of knowledge:Agronomical Sciences - Agronomy
Principal Investigator:Gustavo Habermann
Grantee:Amanda Naves Beraldo
Home Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil


The light capture is a low-efficient process in plants, as they effectively use only 8% sunlight. A better distribution and penetration of sunlight within the plant canopy is observed in plants with vertical leaves (paraheliotropic and/or static vertical leaves) because light may be intercepted by both leaf surfaces (adaxial and abaxial sides). In this way, photoinhibition, water deficit, leaf heating, irradiance excess, and auto-shading are minimized. These responses have been studied using instantaneously measured parameters (leaf gas exchange, fluorescence, leaf pigments). However, little is known about the effects of different leaf angles on the conversion of sunlight into biomass. We hypothesize that the biomass production in plants with leaves artificially maintained at the vertical position is higher than those with leaves forced at the horizontal position. We will use pots (50 L) to cultivate 30 sugar-cane plants (Saccharum oficinarum L. cv. IACSP95-5000), of which half will have their leaves artificially kept at the vertical position, and the other half will have their leaves forced at the horizontal position. After approximately six months, the leaf area (cm2) will be determined and the distinct plant organs will be set apart and oven-dried (60°C) for obtaining the total dry mass (g) and the percentage distribution of dry mass for each plant organ. Data will be submitted to a one-way analysis of variance (ANOVA), and mean results accompanied by their respective standard deviation may be compared by the Tukey test (± = 0,05). Therefore, if biomass is higher in plants with leaves forced at the vertical position, in relation to those maintained at the horizontal angle, we will be able to accept our hypothesis that the vertical leaf position promote higher light use efficiency, and consequently influence the biomass production.