TY - JOUR AU - JUNE, TANIA PY - 2011/11/17 Y2 - 2024/03/29 TI - THE LIGHT GRADIENTS INSIDE SOYBEAN LEAVES AND THEIR EFFECT ON THE CURVATURE FACTOR OF THE LIGHT RESPONSE CURVES OF PHOTOSYNTHESIS JF - BIOTROPIA JA - BIOTROPIA VL - 0 IS - 25 SE - Research Paper DO - 10.11598/btb.2005.0.25.213 UR - https://journal.biotrop.org/index.php/biotropia/article/view/213 SP - AB - ABSTRACT  <br />Light gradients within leaves are not included in the model of Farquhar, although a steep light <br />gradient does exist within leaves. For a bifacial  leaf, the model shows good agreement with measured <br />data, but for an isobilateral leaf the model may underestimate photosynthesis measured by conventional <br />gas exchange. Isobilateral leaves easily developed when plants were grown in growth chambers where <br />some light were reflected from the growth chamber metal base onto the lower surface of the leaves during <br />growth, resulting in adjustment of the photosynthetic capacity inside the leaves. This could also happen in <br />the  field when canopy is very sparse and lower surface of leaves was exposed to reflected light from soil <br />surface.  Complications occurred when fitting the light response curves of the electron transport rate, due <br />to the interaction between the quantum yield of electron transport (a2) and the curvature factor (Θ). It is <br />suspected that there may be an interaction with the light gradient  within the leaf. This manuscript <br />discusses the effect of a light gradient inside a soybean leaf on the estimation of Θ. It is shown in the <br />manuscript how the light curves of the isobilateral leaves (at different degree) responded when measured <br />using conventional gas exchange and  how it affected the estimation of  Θ and the electron transport <br />capacity, Jmax. An experiment was conducted to prove the hypothesis that this “out of ordinary” estimate <br />of Θ (and hence Jmax) was due to the unmatched distribution of photosynthetic capacity with distribution <br />of absorbed light.  <br /> <br />Keywords :  light gradient / photosynthetic capacity (Jmax) / curvature factor (Θ) / gas exchange <br /> <br />  ER -