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ABSTRACT: Salt stress is one of the major abiotic stresses limiting crop productivity. Growth of sugarcane which is an important cash crop is affected by various biotic and abiotic stresses. As sugarcane is a glycophyte it do not thrive well in saline soils. Response of two sugarcane cultivars (cv. SPF 234 and cv. HSF 240) was observed in response to various salt levels during the present study. Callus cultures were transferred to the standardized media for callus formation supplemented with various NaCl concentrations (MS + 13.5 µM 2, 4-D + 0-160 mM NaCl; 9 treatments). A variation in callus morphology was observed in both the tested sugarcane cultivars upon transfer to NaCl-containing media. It was found that the callus cultures become brown and necrotic when subjected to salt stress. A general decrease was observed in fresh weights of callus cultures when subjected to salt stress. However less fresh weight reduction was recorded in SPF 234 callus cultures as compared to callus cultures of cv. HSF 240. Hence SPF 234 appeared to be more salt tolerant as compared to cv. HSF 240 under in vitro conditions. This study therefore, is an important step forward in improving salt tolerance of sugarcane by in vitro techniques.
INTRODUCTION
Soil salinity is a major problem that threatens the productivity of crops in many countries of the world including Pakistan (Ashraf, 1994). It has been reported that 397 million hectares of land throughout the world are salt affected (FAO, 2005). Sugarcane is an important industrial cash crop in Pakistan but its annual yield is far below the existing potential. Soil salinity is one of the reasons that result in low productivity of sugarcane (Akhtar et al., 2003). Furthermore, it also decreases the quality of sugarcane juice by decreasing its sucrose content (Lingle and Weigand, 1996). Salt stress is expressed by many morphological and metabolic changes
Plant tissue culture techniques provide a useful tool to produce stress tolerant plants including the plants resistant to soil salinity. These techniques provide a promising and feasible approach to develop salt tolerant plants (Jain, 2001). Not much work has been reported on in vitro selection and response of callus cultures towards salt stress in Sugarcane cultivars growing in Pakistan. The present investigation was conducted...