Influência da luminosidade na fisiologia e morfoanatomia de jequitibá branco (Cariniana estrellensis (Raddi.) Kuntze) e jequitibá rosa (Cariniana legalis (Mart.) Kuntze)

• Autor(a) principal: Portela, Flávia Carolina Santos
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/1222
• topic: Forest succession; Morphophysiological; Anatomy; Biochemistry; Phenotypic plasticity; Estresse; Plasticidade fenotípica; Jequitibá; Stress; Agronomia; Sucessão florestal; Bioquímica; Fisiologia; Morfologia vegetal; Anatomia vegetal; 57

Cariniana estrellenis (Raddi). Kuntze and C. legalis (Mart.) Kuntze are native Brazilian trees which have powerful economic value and are also objects of interest in recovering programs of degraded areas and in commercial plantations. The scarcity of information about their ecophysiological performance under stress conditions complicates their management and conservation. Under these circumstances, this study aimed to evaluate the ecophysiology of this species in a irradiance gradient, through a couple of experiments. In experiment 1, C. estrellensis plants with 12 months old were subjected to four treatments: 40%, 50%, 70% and 100% of irradiance during 104 days. At the end of this period, the following analyses were made: growth, photosynthetic pigment content, gas exchange, chlorophyll a fluorescence, leaf content of soluble carbohydrates, the stem and leaf anatomical characteristics and phenotypic plasticity of the species. In experiment 2, C. estrellensis and C. legalis plants with 14 months old were subjected to two treatments: 30% and 100% of irradiance (shade and sun, respectively) for 30 days. At the end of this period were analyzed the oxidative stress of the species, by quantifying the activity of catalase and ascorbate peroxidase enzymes and by quantifying the photosynthetic pigments leaf content. In experiment 1, plants submitted to 70% of irradiance showed better growth in height and diameter, higher leaf, stem and root dry mass. In 70% and 100% of irradiance, plants showed smallest and thicker leaves resulting in lower leaf total area. In these treatments, plants showed lower chlorophyll a (Chl a) and b (Chl b) content, higher Chl a/b rate, higher carotenoids (Carot) content and lower Chl a/Carot rate. Higher photosynthetic rates were found in plants in 70% and inhibited in 40%, 50%, due to low solar irradiation, and in 100%, possibly due the occurrence of photoinhibition, as showed by flow energy parameters of photosystem II. According to the analysis of chlorophyll a fluorescence, in full sun exposition, plants had lower density of active reaction centers (RC/ABS) and higher energy dissipation (DI0/ABS), which resulted in decreased performance of photosystem II (PIabs ) and total performance (PITotal). The leaf content of soluble carbohydrates was higher in plants in 70%, followed by plants in 100% of irraciance, with the exception of glucose, which did not vary between treatments. The highest leaf thickness in 100% of irradiance was due to the highest thickness of adaxial and abaxial epidermis and of palisade and spongy parenchymas. And the highest stem diameter in 70% of irradiance occurred because of the highest secondary xylem and phloem thickness. In experiment 2, the plants in full sun of both species also showed lower chlorophyll a (Chl a) and chlorophyll b (Chl b) content and higher Chl a/b ratio. Although the carotenoids (Carot) content were higher, what implied in lower Chl a/Carot ratios. Catalase (CAT) activity varied with the time and the species, showing a decrease in C. estrellensis at 16 days, possibly due to photoinactivation, and an increase in C. legalis at 30 days. The ascorbato peroxidase (APX) did not vary according the time, the species or the treatments. The study of phenotipic plasticity showed that C. estrellensis is a plastic species, mainly due to variables of photosynthesis and gas exchange, being able to survive in the irradiance gradient tested, which allows its uses in restoration projects of degraded areas. And, since the ecophysiological analysis showed that C. estrellensis e C. legalis had better performace in moderate irradiance it is suggested that both behaved as intermediate species in the florestal succession process. However, since that photosynthetic pigments concentration and the antioxidants enzymes production inferred higher susceptibility of C. estrellensis to photoinhibition in high irradiance, it is suggested higher viability os the use of C. legalis in restoration projects of degraded areas.