Fluorescência da clorofila a como indicador de tolerância ao calor e à seca em Jatropha curcas L.

Abstract

Jatropha curcas L. (physic nut) is a species of the Euphorbiaceae family, originally from the American continent, whose cultivation has been disseminated in recent years in several regions of the globe, predominantly in tropical regions, due to the quality of the oil produced by its seeds. The species is also used in the recovery of degraded areas, as phytoremediation and in pharmacology. J. curcas is a species that has adaptability to various environments. Knowing that water stress and high temperatures can lead to biochemical and physiological changes that vary from photosynthetic yield to the accumulation of solutes and that the tolerance of plants can be attributed to the degree of adaptation to environmental conditions in cultivation sites. This work aimed to differentiate genotypes of J. curcas regarding the degree of sensitivity to heat and the interference of drought with sensitivity to heat. Clear differences were observed in the PIABS parameter and its components (RC/ABS, φP0 and ΨE0), therefore, we can consider that the thermal response categories of physic nut plants were clearly differentiated: sensitive NEF12, NEF05 and NEF16 tolerant. The relative decreases of PIABS and PITOTAL were variable for genotypes grown at high temperature and tested under water deficit, allowing the selection of genotypes according to the demonstrated sensitivity: less sensitive (NEF07) and sensitive (NEF05). The enzymatic activity of CAT and APX, carbohydrates, pigments and proline accumulation demonstrated that the genotypes have different responses to the same stress