Seedling physiological responses from Ceiba glaziovii (Kutze) K. Skum. to intermittent drought events

The Brazilian Dry Tropical Forest, called Caatinga, has several environmental conditions limiting plant growth and development, requiring the plants that inhabit this phytogeographic domain, physiological and morphological traits to guarantee the perpetuation and survival of the species. The objective of the present work was to evaluate the growth parameters in Ceiba glaziovii, a tree species that occurs in the Caatinga, submitted to intermittent drought. For such seedling of C. glaziovii were subjected to different cycles of irrigation suspension [Control- daily irrigation, S7- irrigation every seven days and SS - total suspension of irrigation until signs of wilt appear]. Height, number of leaves, stem diameter, dry matter of the various organs, root / shoot ratio, leaf area, and the index of plasticity were evaluated. The prolongation of intermittent drought had a significant reducing effect on the growth rates, dry matter production and leaf area of stressed C. glaziovii seedlings compared to daily watering ones. Plant height and stem diameter were the most plastic traits found (IP>0,8). Thus, watering intervals above seven days may severely compromise the production of C. glaziovii seedlings, affecting the growth rates until the accumulation of dry matter. These results demonstrate that this species does not show great tolerance to drought stress during the initial period of its development, suggesting for cultivation of seedlings an adequate water availability or an interval of up to seven days between watering.