Gaseous Exchange of Native Agricultural Species in La Mojana Region in the Face of Increased Temperature and CO2

Most experts who study climate variation trends agree that temperature and CO2 levels have shown an atypical and sustained increase in recent years. The effect will be felt in all sectors of the world economy, but the productive systems of small farmers, given their high vulnerability, could receive a higher impact. Considering that most studies in this area are carried out by measuring the individual effect of some variables, in the present work we evaluated the simulated effect caused by high temperature levels (28, 30, and 32 °C) and CO2 concentrations (380 and 420 μmol mol-1) on important photosynthetic aspects of some native species of small producers in La Mojana region in Colombia (light saturation point [LSP], light compensation point [LCP], maximum net photosynthetic rate [PNmax], and dark respiration rate [Rd]). The species were grouped as vegetables ([i] Cucurbita máxima, Duchense; [ii] Solanum melongena, L.; and [iii] Vigna unguiculata, L y Wald.), transients ([i] Oryza sativa, L. Cv: Chombo; [ii] Oryza sativa, L. Cv: Bogotano; and [iii] Oryza sativa, L. Cv: LV), and perennials ([i] Coffea arábica, L.; [ii] Tabebuia rosea, Bertol.; and [iii] Theobroma cacao, L.). The most relevant results indicated that at normal and high CO2 concentrations, temperature would affect the main photosynthetic responses of the species. The photosynthetic responses of the vegetable species, except for Cucurbita máxima, would be affected if the temperature rose to 30 and 32 °C in either of the two simulated scenarios of ambient CO2. The behavior of the three Oryza sativa varieties was differential; Bogotano rice and LV rice were relatively tolerant to high temperatures under normal or increased CO2 conditions, but Chombo rice would be more sensitive to high temperatures. In the group of perennial species, Coffea arábica and Theobroma cacao were more sensitive and would be affected mainly by high temperatures, whereas Tabebuia rosea would not be affected by temperatures at current ambient CO2 concentrations.