Ecofisiologia e potencial de recuperação de mudas de Campomanesia xanthocarpa (Mart.) O. Berg sob déficit hídrico e sombreamento

Abstract

Guabiroba (Campomanesia xanthocarpa (Mart.) O. Berg) is a native tree in the Brazilian Cerrado that has a wide geographic distribution throughout the national territory, has several socioenvironmental potentials. To improve the utilization of water resources to produce quality seedlings or the implementation of projects to recover degraded areas and reforestation, it is necessary to know the physiological and morphophysiological responses of the species to the different environmental factors. The ability of species to withstand water stress is critical for their distribution along a gradient of regeneration of clearings. The objective of this work was to evaluate the effect of the water deficit on the gaseous exchange responses, antioxidant enzyme activity and the growth of C. xanthocarpa seedlings submitted to different shading conditions, as well as the recovery potential of after normal water supply. This work was divided into two chapters: In the first chapter, gas exchange, leaf area, relative water content (RWC), height, number of leaves and root length were evaluated. In the second chapter are the Dickson quality index of seedlings (DQI), water potential (ᴪw), Chlorophyll index, the efficiency of the photosynthetic apparatus and antioxidant activity of C. xanthocarpa seedlings under different water availability. The seedlings submitted to the water deficit and cultivated under 0% shading had a reduction in the relative water content, all photosynthetic metabolism characteristics and aerial part, which recovered with water restoration. Under intermittent irrigation at 0% shading, the seedlings had a higher antioxidant response. It was observed that shading 30 and 70% reduced the water stress in the seedlings under intermittent irrigation, and that after the water supply all characteristics recovered, except for the activity of the POD and SOD enzymes, which remained high. Therefore, it is suggested that the evaluation days of the recovery be prolonged, to allow the seedlings to regain the activity levels of the enzymes.