Influência da sazonalidade sobre a ecofisiologia, e estimativa da área foliar em função de dimensões lineares do limbo foliar de Erythroxylum simonis Plowman

Abstract

Echophysiological studies are fundamental to seek understanding of the plant environment relationship. Seasonal variations may influence the ecophysiology of species located in the understory. Non-destructive studies to determine the leaf area have been highlighting, using leaf blade variables. In this context, the present research had as objectives to evaluate the effect of seasonality on Erythroxylum simonis ecophysiology as well as to construct and propose the best equation to estimate leaf area of the species, from leaf dimensions. The research was developed in the Mata do Pau-Ferro State Park, Areia-PB, Northeastern Brazil. In chapter I, the objective of this study was to evaluate the effect of seasonal variation on the ecophysiology of E. simonis. The ecology and environmental variables were read bimonthly at different times of the year: dry season (September, November and January) and rainy season (March, May and July). The indexes of canopy structure (leaf area index, visible sky fraction and photosynthetically active radiation), soil moisture, monthly temperature and monthly precipitation were evaluated and their effects on gas exchange and relative chlorophyll content were evaluated. There was greater influence of rainfall and soil moisture on stomatal conductance, transpiration, internal carbon and photosynthesis rate of E. simonis, evidencing the influence of water availability on the ecophysiology of the species. There were significant differences in the rate of photosynthesis, internal CO2 concentration, transpiration, stomatal conductance, instantaneous water use efficiency and chlorophyll content at different times of the year. In Chapter II, the objective was to construct and propose an equation to estimate the leaf area of E. simonis, from linear leaf blade size of the species. 200 leaf limbs of the species were collected in the study area. Statistical models were used: linear, simple linear, quadratic, cubic, power and exponential. All the equations presented can be used to estimate the leaf area of E. simonis but from the practical point of view, it is recommended to use the simple linear regression equation, xi involving the product between length and width (LxL), using equation 0.6426 * CL, with R2 0.9936.