Germinação do pinhão, crescimento e teste hídrico de mudas de Araucaria angustifolia (Bertol.) Kuntze

Abstract

The factors that influence the germination and growth of seedlings of forest essences are important for obtaining individuals with high vigor. Thus, the study aimed to characterize and evaluate the germination rate of pine nuts, growth of morphometric variables and determine optimal water levels of Araucaria angustifolia (Bertol.) Kuntze seedlings. Pine nuts were collected (June/2019) in three municipalities in Santa Catarina (Capão Alto, Lages and São José do Cerrito) located in the Serra Catarinense. In the laboratory, the characteristics of pinion dimensions were measured: length (C), width (L), stem (Cb) and weight (Ps). With weekly measurements (from March to September/2020), the following seedling morphometric variables were measured: base diameter (db), height (h), crown proportion (Pc) and four crown radii (rc) according to positions cardinals (north; east; south and west). The description of the growth of the morphometric variables was evaluated by adjusting regression models with linear [x], quadratic [x2], inverse [1/x] and logarithmic [ln (x)] terms. For the evaluation of the water test, different levels of water requirement per seedling were considered during weekly monitoring (from July to September/2020). Thus, four treatments were established: T1 [100 ml], T2 [200 ml], T3 [300 ml] and T4 [400 ml]; irrigated once a week. From the analysis of the results it is possible to conclude that there was variation in the dimensions of the collected pine nuts. The models chosen for modeling the morphometric variables were taken into account the highest value of the coefficient of determination (R²), the lowest residual standard error (Syx), the highest calculated F value. The linear regression model was better for expressing growth in height (h) and crown radius (rc), based on the analyzed statistical criteria. From the water test data, he found that the best water levels are between 200 ml and 300 ml. Evaluating the repeated measurements of the current weekly increments for the different water tests, the increments in height (Ih), crown proportion (IPc) and crown radius (Irc) showed significant differences in time and treatment.