Fenologia e capacidade fotossintética do pinhão-manso (Jatropha curcas L.) Em diferentes épocas do ano no estado de Alagoas

Abstract

The physic nut (Jatropha curcas L.), is a native plant of the Americas which belongs to the Euphorbiaceae family. There is a process of domestication of the species, being considered an agricultural option for the Northeast region, for being a xerophytic species that adapted to regions of less fertile soils and of unfavorable climate conditions than most of the traditional alimentary cultures. Part of the interest for the cultivation of this species is related to the use of the seeds for oil production for the obtainment of the bio-diesel. This work was developed with the objective of charactering the phenology behavior of the physic nut in semi-humid region (Zone of Mata) and to compare the leaf gaseous exchanges and photochemistry efficiency of the physic nut in two regions with distinct climates, Agreste (semi-arid tropical climate) and Zone of Mata (semi-humid tropical climate) of the state of Alagoas. The physic nut presented vegetative growth with standard sazonal, slow growth was verified in the dry season, and acceleration of the growth in the rainy season. The budding and fructification peak occurred during the rainy season. The development cycle of the fruit lasted an average period of 120 days from the sprouting of the inflorescence until the complete matureness of the fruit on the plant. The physic nut plants presented less decreases in the photosynthesis taxes, stomata conductance and transpiration in the dry seasons. The highest vapor pressure deficit (in dry season) was the main responsible factor for the closing the stomata in the physic nut, which contributed to the reduction in the tax values of the liquid photosynthesis. During the dry season, around noontime, a dynamic photoinhibition occurs with a fast recovery during the afternoon in physic nut leaves. However, in the semi-arid region, with severe water deficit there can be chronic photoinhibition.