Ecofisiologia e crescimento inicial de Inga vera willd. sob níveis de sombreamentos e regimes hídricos

Abstract

Inga vera Willd. is a species of great medicinal and food potential with an effective contribution to ecosystem services. The objective of this work was to evaluate the effect of shading levels and water regimes on photosynthetic metabolism and quality of I. vera seedlings. The seedlings were cultivated under three water regimes, based on the substrate's water retention capacities (CRS): 50%, 75% and 100% and three levels of shading (0% - full sun, 30% and 70%) and evaluated in three periods, being: 25 and 50 days after the submission of the water regimes. After this period, 75% CRA was maintained in all plants for 30 days, characterizing the recovery period (REC). The characteristics of gas exchange, chlorophyll a fluorescence, relative water content, chlorophyll a, b and total index were evaluated. Dickson quality index (DQI), proline content, peroxidase enzymatic activity and total protein content. There was a reduction in photosynthetic rate (A), stomatal conductance (gs), transpiration (E), Rubisco carboxylation efficiency (A/Ci), internal CO2 concentration (Ci), potential photochemical quantum efficiency of photosystem II (Fv/Fm), efficiency of absorbed energy conversion (Fv/F0) and basal quantum production of non-photochemical processes (F0/Fm) in seedlings grown in full sun in all evaluation periods, regardless of the water regime. The highest values of relative water content (CRA) in I. vera leaves were observed at 75% of shading after REC and the water use efficiency (WAE) did not differ statistically between treatments for the same period. There was an increase in the levels of chlorophyll a, b and total in seedlings grown in shade. In general, the highest v averages of leaf area (AF) were observed in seedlings grown at 30% shade regardless of the water regime. The root length (CR) showed an isolated effect with the evaluation periods and treatments, with higher values under 0% of shading and with 100% of CRS (62.88 cm). Seedlings grown under full sun and 30% shading showed higher quality indices (IQD). As for the osmoprotective activity in the roots and leaves of I. vera cultivated at 0% and 30% with lower CRS, in general, higher concentrations of proline were found. Regarding the antioxidant activities, the activity of the enzyme peroxidase in the leaves of I. vera showed greater variations between treatments when compared to the roots. Seedlings under 30% shading and 75% CRS had higher concentrations of total protein in leaves and roots. The shading mitigated the effect of low water availability in I. vera seedlings, keeping the photosynthetic rate high and, when cultivated under full sun (with up to 75% CRS) and 30% shading, they showed higher seedling quality and vigor, not being observed under these conditions significant damage to the photosynthetic apparatus.