The photoperiod and the gibberellin stimulates the growth of Sterculia striataafter the dormancy

Abstract

Sterculia striataSt. Hill & Naudin (Malvales -Malvaceae)occurs in the Brazilian Cerradoand displays foliar fall and vegetative dormancy in the season of decrease inphotoperiod and water availability. Here, it wasinvestigated the possibility forthese abiotic factors influence the resumption of growth in this specie. For this purpose, the photoperiod was increased (3h) and plants wereirrigation or not. The increase of the photoperiod was critical for the plants to initiate the resumption of growth and to expand the leaf area, because the same occurred under conditions of total water restriction reaching 221.7 cm ² of leaf area at 90 days. In addition, it stimulated a greater growth because at the 90 days of experiment, in the increased photoperiod and irrigation the leaf area was of 1.969,2 cm² while withnatural photoperiod and addition of water this value was 1,377.8 cm². In the treatment with natural photoperiod without water the leaf area was 7.2 cm² per plant. Thus, the water was crucial for leaf expansion, however, regardless watersupplement, the increased photoperiod provided growthresumption. This means that the species uses photoperiod as a signal for growth after its natural dormancy. During the growth resumption of plant S. striatathe stem length was influenced by the hormone gibberellin. In order to use this specie for landscaping and reforestation purposes, S. striataseedlings may be exposed to photoperiod manipulation and hormonal application in order to manipulate growth and produce vigorous seedlings