Efeitos de diferentes pré-tratamentos de sementes na germinação, desenvolvimento e produção do algodoeiro (Gossypium hirsutum L.) em meio salino.

Abstract

The objectives of the present study were to determine the effects of different pre-treatments of seeds and leveis of salinity on germination, seedling vigor, growth and production of two cotton (Gossypi um hi rsutum, L.) cultivars. Under controlled conditions of temperature and relative humidity, using the paper towel methodology, the effects of three leveis of salinity and eight pre-treatments cf seeds on germination and vigor of cotton cultivars Reba B-50 and BR-1 were studied in the first stage. A completely randomized factorial design with four replications was adopted, Each replication consisted of 35 and 10 seeds for germination and vigor counts, respectively. The results obtained indicate that increase in NaC1 concentration decreased percentage of germination and seedling vigor of both cultivars, however, BR-1 was found to be more vigorous. The pre-treatment of seeds significantly increased vigor index and germination, but differences among the pretreatments were not appreciable, nevertheless , seed hydration and soaking in 0.1N NaC1 with subsequente drying gave the best results for vigor and germination respectively. In the next stage, effects of three pre-treatments and three salinity leveis on germination, vegetative growth, components of production and yield of two cotton cultivars in a green house under natural conditions were studied. The soil utilized in this experiment was a Red Yellow Podzol of Surubim - PE. The experiment was carried out in a completely randomized factorial design with three replitations. The results showed that percentage of germination, height of plants and dry weight of shoot at harvest of both cotton cultivars, as well as shedding/plant for BR-1 were only affected by the highest salinity levei (10,0 mmhos/cm of electrical conductivity). Hydration of seeds in wa ter with subsequente drying resulted in increased root weight independent of cultivar, and in relatively more number of flowers and shedding/plant for Reba B-50. The mean weight of cotton boi 1 and total production were not affected by the treatments under study, but it seems that the low levei of fertilization and the little volume ofsoil used in the present study, masked the effects of salinity and pre-treatments on production and its components.