Abstract
Plants in the tropics are exposed to high radiation and consequently high temperature and evaporative demands throughout the year. Under these conditions, physiological processes and final yield may negatively affect crops. Responses of C. chinense to different light conditions were evaluated in open-field conditions. Two experiments were performed: In the first trial, C. chinense plants were grown under Passiflora edulis shade and under full sunlight. In the second, three light conditions (60 %, 40% and full sunlight) were assayed employing synthetic meshes. Microclimate measurements and gas exchange characteristics were evaluated. Partial shade resulted in lower VPD. Shade plants exhibited lower mean daily and total CO2 assimilation rates compared to full sunlight plants. Partial shade induced lower stomatal aperture, regulated by light intensity; while the influence of VPD on stomata closure was less pronounced. The acclimation of sweet pepper to shade conditions was evident by lower chlorophyll Chl a/b concentrations.
Highlights
Variations in light intensity experienced by plants under open-field conditions can notably influence their photosynthetic activity
Due to the non-homogeneous shade to which C. chinense plants were subjected, mean incident Photosynthetic photon flux density (PPFD) received by the aerial parts of the plants was approximately 700 μmol m-2 s-1
Mean PPFD under the cover provided by passion fruit vines represented a 56% of total global sunlight, which does not necessarily constitute the total amount of incident PPFD for all of the C. chinense plants, due to the irregular arrangement of passion fruit stems and leaves
Summary
Variations in light intensity experienced by plants under open-field conditions can notably influence their photosynthetic activity. Any modification in the photosynthetic structure due to variations in light conditions (Osmond et al, 1999, Murchie et al, 2005) will affect other metabolic processes such as growth and yield. In the case of C. annuum, a functional decrease in photosystem II activity accompanied by an increase in accumulative exposure of photons has been observed. This trend is more pronounced in plants grown under low compared to high radiation conditions (Lee et al, 1999)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
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 call