Effect of Fes[O.Sub.4] and Ph on Shoot Regeneration from the Cotyledonary Explants of Tossa Jute (Report‪)‬

Introduction Tissue culture techniques have become an attractive field of biotechnological research. The benefits of these studies are particularly valuable in the areas of large-scale clonal propagation, crop improvement, the production of important plant compounds and the conservation of genetic resources. The development of shoot regeneration efficiency requires a better understanding of the influence of culture conditions on shoot regeneration. Ferrous sulphate is the main source of iron and sulpher energy for in vitro cultures. Plant cells and tissues in a culture medium lack autotrophic ability and therefore, need external FeS[O.sub.4]. The addition of an external iron and sulpher source to the medium enhances the proliferation of cells and regeneration of green shoots. The optimal FeS[O.sub.4] concentration in a medium should be sufficient to satisfy the basic energy requirements for cell division, differentiation and not impose any negative osmotic effects on shoot formation. This indicates that different concentrations of FeS[O.sub.4] are one of the factors controlling the induction and growth of shoots. The growth of the shoots also affected by the different concentration of sucrose (Gibson, 2000; Gurel and Gulsen, 1998). Plant cells and tissues require an optimum pH for growth and development in cultures. The pH affects nutrient uptake as well as enzymatic and hormonal activities in plants (Bhatia and Ashwath, 2005). The optimal pH level regulates the cytoplasmic activity that affects cell division and the growth of shoots and it does not interrupt the function of the cell membrane and the buffered pH of the cytoplasm (Brown et al., 1979). The changes in external pH have a small transient effect on cytoplasmic pH but the cells are readily readjusted towards their original pH (Parton et al., 1997), thus the effect of external pH on cytoplasm is not long lasting. However this change may affect plant growth as follows. Exposure of cells to extreme low pH leads to conversion of inorganic phosphate into organic phosphate at the extracellular region. This is also accompanied by a reduction in ATPs which leads to reduced plant growth (Mimura et al., 2000). The detrimental effects of adverse pH are generally related to an imbalance in nutrient uptake rather than to direct cell damage. The pH also influences the status of the solidifying agent in a medium: a pH higher than 6 produces a very hard medium and a pH lower than 5 does not sufficiently solidify the medium (Bhatia and Ashwath, 2005). Therefore, it is necessary to optimize the FeS[O.sub.4] concentration and pH level for maximum shoot regeneration because the FeS[O.sub.4] concentration and pH level directly influence shoot regeneration.