INDOLE-3-BUTYRIC ACID APPLICATION MITIGATES SODIUM CHLORIDE STRESS IN TWO COTTON CULTIVARS DIFFERING IN SALT TOLERANCE

摘要

Soil salinity is a major constraint to food production because it limits crop yield and restricts the use of land previously uncultivated. Breeding for tolerance to salinity in crops has usually been limited by the lack of reliable traits for selection. The mechanism of salt tolerance in two cotton (Gossypium barbadens L.) cultivars (Giza 70 and Giza 88) and their responses to shoot spraying with 200 ppm m(-3) IBA were studied.Treatment with IBA not only improved the growth of salt-affected Giza 70, but also increased the growth of this cultivar up to -2.7 MPa and reduced the inhibitory effect of salinity on photosynthetic pigments.This was accompanied by differences in the accumulation of sucrose and total soluble sugars and in the total available carbohydrate and protein contents. IBA ameliorated the inhibitory effect of salinity on growth, increased the carbohydrate and protein contents of both cotton cultivars and markedly retarded the accumulation of proline and glycine betaine. It resulted in the reduction of Na+ accumulation in Giza 70, while in Giza 88 it enhanced the absorption and translocation of K+, resulting in higher K+/Na+ ratios in the shoots. There were pronounced differences in the electrophoretic patterns of the proteins in both cultivars under salt stress and IBA treatment.