Efeito da temperatura, pré-embebição e salinidade na germinação e vigor de sementes de algodão (Gossypium hirsutum L.).

Abstract

The objectives of the present study were to study the effects of hydration (presoaking of seeds ), temperature and salts of different concentrations on germination and vigour of cottonseed (Gossypium hirsutum L . } . The study was carried out under controlled conditions of temperature and relative humidity using paper towel as substrate In a randomized factorial design wi th six replications, the effects of hydration and different concentrations of NaCl (0, 100 & 200 meq/1.) on germination and vigour of 11 cottonseed cultivars (BR-1, Allen 333/57, Reba B-50, SU-0450/8909 , ST0-731N, M C U - 5 , H G N C S N - 1 0 - 7 , HG-18-45-N, Acala dei Cerro, Shankar-4 & HGP-9-13] were studíed at 2 5 Ç C The first four cultivars are largely utilized in Northeast while the others are still in introductory stages. The results indicated that the percentage of germination and vigour of ali the cultivars under study decreased with increased salt concentrati on irrespective of hydration treatment, however, latter was found to be significantly superior when com pared to no treatment except cultivar SU-0450/8909. For germination as well as for vigour, statistical analysis of data showedhighly significant (0,01 levei) effects of cultivars, salt concentration, presoaking and their intereactions. However. BR-1 Reba B-50 and Acala dei Cerro were found to perfomanc better in saline substrate than others. In the next stage, effects of temperature ( 20 & 30ºC) and salts of different concentrations (control alongwith Solutions of 100, 200 & 300 meq/l of NaCl and.NaCl + CaCl- in 2:1 & 1:2 proportion) were studied on germination and vigour of cultivars BR-1 and Reba B-50 using hydrated seeds in a randomized factorial design (2 x 2 x 10) with four replications. The results showed that incorporation of Ca ions insaline soluctions increased percentage of germination and vigour index of the cottonseed cultivars, however, at 2ÒºC these processes were found to be substantially reduced. Althouhg, at 209C no significant differences were observed in the vigour index of cultivar BR-1 and Reba B-50, perfomance of former was found to be significantly. better at 30ºC Further, a highly significant interaction between temperature and type of salt solution was found for the germination and vigour, thereby indicating possibility of overcoming deleterious effects of salt coneentration and 1 ow temperatures by incorporation of Ca ions in the saline medium.