Physiological responses of photosynthesis in black pepper plants under different shade levels promoted by intercropping with rubber trees

Abstract

Plants of black pepper (Piper nigrum L.) may display changes in their photosynthetic activity as a result of environmental seasonal changes. Intercropping with tree species may represent an alternative to mitigate the impacts of climatic changes on crops. The objective of this work was to evaluate the physiological responses of photosynthesis in black pepper plants under different shade levels promoted by intercropping with rubber trees (Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. The photosynthetic performance in black pepper along the day was evaluated under full sun and five shade levels. The resulted showed that variations positives in leaf gas exchanges were not exclusively dependent on the shade promoted by the distance in relation with the line of rubber trees in the field, but also fluctuate depending on the period of the day, the orientation (Northern or Southern), relating the line of trees and the season of the year. This study showed that shaded intercropped plants displayed some advantage in a few cases (black pepper plants located at 2 m, and 5 m between rubber trees, southern side) as regards the photosynthetic rate at midday and afternoon, and especially in summer, when compared to pepper plants cultivated in full sunlight condition, That would be likely related to the to the maintenance of somewhat lower temperature and higher relative humidity in the atmosphere close to the black pepper plant implying some advantage for such consortium system to mitigate the possible effects of future climate changes, like warming.