Morfologia de frutos, sementes e plântulas, e qualidade física e fisiológica de sementes de Gallesia integrifolia (Spreng.) Harms

Abstract

Gallesia integrifolia is a native forest species, that have timber, medicinal, photochemical, landscaping potencial, and is used in restoration of degraded areas. This study aimed to characterize morphologically and to investigate physical quality and biochemical changes of garlic wood seeds at different stages of germination; to evaluate germination and vigor of G. integrifolia seeds under different substrates and temperatures; and to determine the optimum, minimum and maximum germination temperature for G. integrifolia seedlings. The structures of fruits, seeds and seedlings were evaluated. The physical characterization of seeds involved analysis of purity, water content, mass and water absorption pattern. Biochemical changes during the stages of germination were evaluated by quantification of lipids and soluble sugars. The influence of different substrate and temperatures was evaluated by randomized plot in time with 6 x 5 (6 substrates: sand, vermiculite, GoldenMix®, Plantmax®, on paper, and paper roll; and 5 temperatures: 15, 20, 25, 30 and 35 °C), with four replications of 25 seeds. germination (%), speed of germination, the relative frequency of germination, mean germination time, normal seedlings (%), length, dry and fresh mass of shoots and roots of seedlings were evaluated. To define cardinals’ temperatures the seeds were placed in paper roll (germitest) and random samples of 25 seeds each were incubated separately at constant temperature of 10,0 12,5, 15,0 17,5, 20,0 22,5, 25,0 27,5, 30,0 32,5, 35,0 37,5 and 40 °C, respectively, with photoperiod of 8 hours. The fruit of G. integrifolia is an indehiscent brown samara. The seed is circular and laterally compressed, with a punctiform hilum located at the base of the seed. Germination is epigeal and phanerocotyledonal, starting on the third day, can be finished on the 15th day after sowing. Seedlings have pivoting primary root; green, smooth and elongated hypocotyls; green, foliaceous, cordiform, glabrous, opposite and petiolate cotyledon. Seeds with 10.7% moisture showed mass of 1000 seeds of 43.4 g and 23040 seeds kg-1. Physical purity was 69.4%. The germination follows the three-phase pattern. Phase I lasted two hours and phase II lasted up to 24 hours, at 48 hours initiated phase III. At 72 hours was observed the primary root protrusion. The content of soluble sugars and lipids showed a decrease during seed germination phases. At 120 hours was observed increase of contents of these compounds. Plantmax® and the paper roll substrates, and temperatures between 20 and 30 °C are the conditions recommended for the testing of germination and vigor in G. integrifolia seeds. The minimum germination temperature was 12.5 °C, the maximum temperature to obtain normal seedlings was 32.5 °C. Temperatures between 22 and 30 oC seemed most favorable with normal seedlings in excess of 50%. The temperature of 30 °C produced the highest percentage of normal seedlings and average rate.