GAS EXCHANGE, GROWTH, FLOWERING AND FRUIT PRODUCTION IN SWEET PEPPER ( CAPSICUM CHINENSE JACQ ) ALONG A THERMAL GRADIENT DETERMINED BY ALTITUDINAL DIFFERENCES IN A TROPICAL REGION

A common practice in some South American countries consists in moving around Capsicum chinense cultivars between regions where edaphoclimatic conditions differ notably. The purpose of this research was to compare and relate gas exchange responses with assimilate allocation patterns and flower and fruit production dynamics in a cultivar of C. chinense in three locations with different mean temperatures (19, 24 and 28 °C) along a gradient from 140–1855 m. Leaf gas exchange (leaf conductance, CO2 assimilation and transpiration rates) was measured at 60–70, 110–120 and 140–150 days after transplanting (dat) from seed beds. Dry weight per plant of leaves, stems and roots were determined at 50, 73, 96, 114 and 196 dat. Flowering dynamics and fruit production were followed weekly. A marked reduction (50%) in mean Gs was found at the site with the lowest mean temperature in relation to plants grown at the highest temperature site. Mean daily CO2 assimilation rate was higher for plants in the intermediate site and a reduction of 18 and 42% was found for sites with highest and lowest mean temperature, respectively. We report an adverse effect of low temperatures on growth of C. chinense. Flowering initiation and fruit production was delayed at lower temperatures. An increase in temperature (between 26–30 °C) led to an increase in the number of flowers; below this temperature it remained unchanged. Fruit production is drastically reduced at the lower temperature site due to a large number of aborted flowers and small fruits.