Déficit hídrico e aplicação de metil-jasmonato sobre as trocas gasosas, síntese de compostos fenólicos e formação de raízes tuberosas em batata-doce

Abstract

Sweet potato is a crop with wide adaptability to different climatic conditions; however, its yield can be affected by prolonged periods of water deficit. The exogenous application of jasmonates can modulate several physiological and biochemistry, such as plant resistance to abiotic stress. Based on the hypothesis that the water deficit can be attenuated with the application of MeJA in sweet potato plants during the formation of tuberous roots, this study sought to evaluate the photosynthetic performance and the phenolic concentration present in the leaf and root associating them with the partitioned dry mass, mainly in relation to the production of tuberous roots. The experimental design was completely randomized, arranged in a 2 × 2 factorial scheme, composed of two levels of MeJA hormone (presence and absence) and two levels of irrigation (100% and 40% of field capacity). The plants treated with MeJA showed a reduction in AF and MSF, but increased the MSRA, suggesting that the assimilated carbon was allocated to the production of adventitious roots in detriment of the tuberous roots, which resulted in less expansion of the leaves. The application of MeJA in sweet potato plants affected photosynthetic performance, however it increased the production of antioxidant phenolic compounds and proline, proving to be important for the synthesis of secondary metabolites. The response mechanisms evaluated showed that the severity of water deficit was more prominent than the effect of MeJA. Thus, the positive biochemical changes resulting from the application of MeJA were not sufficient to alleviate the stress caused by water deficit, which reflected in a lower production of tuberous roots.