Physio-anatomic aspects on the initial growth of Guazuma ulmifolia Lam. seedlings (Sterculiaceae)

Abstract

This paper aimed to evaluate the initial growth of "mutambo" seedlings in different conditions of light intensity and treatments with gibberellic acid (GA). The seedlings were kept under full sun and 50% of shading. Sixty days after the emergence, seedlings were sprayed with: 1) 100 mg L −1 GA 3 ; 2) 200 mg L −1 GA 3 ; 3) control. At the end of the appraisals, seedlings height under 50% of shading was compared to the height that were growing under full sun with 200 mg L −1 GA. Stem diameter was lower under shading. Leaf area did not vary among the treatments, but the root system growth was higher under full sun and did not vary among GA levels. The number of stomata, trichomes and epidermal cells on adaxial and abaxial sides was higher under full sun. Total dry masses of leaf and root were higher under full sun and with 200 mg L −1 GA application. "Mutambo" seedlings presented a higher initial growth under full sun, although with a lower height, diameter, and lenght of the largest root and total dry masses of leaf and root were higher. A concentration with 200 mg L −1 promoted a higher growth.