Mecanismos fisiológicos e bioquímicos em mudas de jatobá (Hymenaea courbaril L.), sob condições adversas.

Abstract

Among the tree species native to Brasil, the jatoba (Hymenaea courbaril L.) has been the subject of several studies addressing its potential in carbon sequestration, as well as restoration of degraded environments. However, the physiological responses on the water stress, salinity and nutritional plants jatoba are practically unknown. In order to clarify some of the relationships between these processes, the present study aimed to evaluate the effects of suppression water, salinity and omission of N, P and K in the physiological behavior of seedlings jatoba. To conduct this work were conducted three experiments in the greenhouse of the Laboratory of Plant Physiology, Department of Biology, Universidade Federal Rural de Pernambuco, Recife, Brazil. Therefore, the plants were propagated from seeds collected in two regions of occurrence of the species, in the Pernambuco State. The first trial addressed the effects of water stress by suppressing irrigation and later irrigation, while for the evaluation of salt stress, we conducted a test checking the deleterious effects of the incremental addition of NaCl (0, 50 and 100 mM), hydroponically, and finally the effects of omission of N, P and K were evaluated in the third trial. In all experiments, the parameters were evaluated for growth, gas exchange, water relations, photosynthetic pigments, quantum efficiency of photosystem II and biochemical aspects by quantification of compatible solutes. The results of this study infers that jatoba seedlings have a tendency to accumulation of photosynthetic pigments and organic solutes, mainly proline as the main features of coping suppression watering. Fact allowing rapid reestablishment of their metabolism after rehydration in the early stage of development. Another fact that should be emphasized is that there is evidence that they bear up to 12 days of drought without compromising your metabolism. Information that may be useful to reforestation programs and producing seedlings of the species. Regarding the behavior versus salinity, it is concluded that the jatobá plants osmotically adjusted, once accumulated organic solutes that promote the increase of leaf turgidity, resulting in the continued growth and stabilization of gas exchange, even after subjection to stress severe salt (100 mM). Among the variables is recommended to evaluate the levels of chloride, sodium and potassium in the leaves, stems and roots for the characterization of the state of tolerance to salinity changes of jatoba. Regarding the behavior of seedlings by omission of N, P and K was observed that N was the most limiting macronutrient development of jatoba plants, suggesting that the nutritional requirement regarding macronutrients of that species obeying the order of decreasing N> P> K. It is hoped that the results obtained in this study may elucidate the main mechanisms used by jatobá to tolerate abiotic stresses and that information is useful for establishing adequate management exploitation of the species, since the ease of obtaining seedlings and its occurrence in areas prone to various environmental stresses, enhance its use in the processes of reclamation and / or reforestation.