Induced genetic variability for tolerance to salinity, pH and photoperiod in stem nodulating Sesbania rostrata

The stem nodulating green mature plant Sesbania rostrata and its late flowering mutant, TSR-1, were studied for their response to abiotic stresses, namely, salinity, pH and photoperiod. Three genotypes, S. rostrata, TSR-1 and S. aculeata, were planted in pots containing soil (soil + farm yard manure (FYM) and soil - FYM) with electrical conductivity values ranging from 0.08 to 5.3 mmhos/cm2. The range of salinity used did not adversely affect plant growth in any of the genotypes. Salinity induced better growth when the soil had no FYM. Salinity did not affect stem nodulation, the number of nodules being commensurate with plant growth. The high level of salinity in soil + FYM reduced the percentage N. However, in soil - FYM, the salinity did not affect the N content, although a marginal increase was observed. The percentage N was reduced by the high pH of the medium. Radiotracer studies showed that in S. rostrata and TSR-1 less Na was translocated to the stem and leaves than was taken up. Exposure to a short photoperiod induced early flowering in the parent but not in TSR-1. Despite being exposured to a short photoperiod at four different stages of growth it flowered, along with the control, after only 220 days. Polyacrylamide gel electrophoresis showed repression, overexpression or induction of polypeptide bands by growing the seedlings of different genotypes in 200 mM NaCl