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INTER  AND INTRA  SPECIFIC VARIATION FOR SALT TOLERANCE IN TURNIP (BRASSICA RAPA L.)  AND  RADISH (RAPHANUS SATIVUS L.) AT THE INITIAL GROWTH STAGES

ZAHRA NOREEN^* AND MUHAMMAD ASHRAF

Abstract: Exploration of inter- and intra-specific variation for salt tolerance is a pre-requisite for the improvement of this trait through selection and breeding. In order to assess, inter- and intra-specific variation for salt tolerance in radish (Raphanus sativus L.) and turnip(Brassica rapa L.), local cultivars of these two species were screened at varying levels of salinity stress (0, 60, 120, 180, and 240 mM) at the germination and seedling stages. Increasing level of salinity caused a marked reduction in germination percentage and fresh and dry biomass of the seedlings of all cultivars of both species. Both species displayed highly significant intra-specific variation in seed germination and seedling growth at higher levels of salt. However, the degrees of salt tolerance at the germination and seedling stage varied in both species. Of turnip cultivars, Shaljum desi surakh was highest in seed germination, while it was lowest in seedling shoot dry biomass production. However, Neela Shaljum having lower seed germination percentage produced maximum seedling shoot dry biomass. In the same way, cv. Desi of radish with minimum seed germination had highest shoot dry weight under saline conditions. Although a considerable magnitude of variation for salt tolerance was observed in a set of available local cultivars of both species at the germination and seedling stages, the performance of cultivars of both species was not consistent across different stages, thus this needs to be further investigated at later growth stages. On the whole, radish was found to be tolerant as compared to turnip in terms of tolerance index worked out using overall germination percentage and seedling shoot dry weight.
 

Department of Botany, University of Agriculture, Faisalabad 38040, Pakistan