Somaclonal Variation in Sugarcane Through Tissue Culture and Subsequent Screening for Salt Tolerance

Abstract

The arid zones of Dera Ismail Khan (NWFP) has great potential for growing agricultural crops. Due to commissioning of Chashma Right Bank Canal, about 0.2 million hectare of land is being irrigated. However, salinity is the main curse in this area. Past use of brackish water by tube-well scheme has further deteriorated the land capability for growing crops. Sugarcane is one of the important cash crop of the area. A sugar mill has been installed in this area resulting in the extensive cultivation of sugarcane. However, none of the cultivated varieties have sufficient salt tolerance. The average yield is very low ( 15 tons/hectare) compared to the yield obtained in other part of the country. The situation demand for cultivation of salt tolerant cultivars of sugarcane. The use of tissue culture for creation of somaclonal variation in plants for development of salt tolerant cultivars offers advantage overall other conventional methods. The method is very efficient and has tremendous potential for producing novel and useful varieties ( Larkin and Scowcroft, 1981). Taking advantage of this method a research project was started in June 1996, at the faculty of Agriculture, Gomal University, D.I.Khan, to develop suitable cultivars of sugarcane with salt tolerant characteristics. A modified basal MS medium was prepared. Young leaves of high yielding cultivars of sugarcane (Genotype CP-43/33) were used as explant. The sterilized pieces of explant were allowed to form callus under dark conditions at required temperature of 28±2 °C. The pH of the medium was adjusted to 5.8 before autoclaving. The whole experiment was conducted under aseptic conditions. The callus was formed and plantlets were developed form it. The plantlets were hardened in jars containing sand and later on these plantlets were transformed to pots containing mixed soil. The grown up plants (somaclones) were transplanted from pots to fields. The setts of well developed plants were allowed to germinate in saline and sodic soils of the research field of the faculty. Screening of salt tolerant somaclones was made and data was recorded on the characteristics like: sett germination, number of tillers/plant, stem height, number of nodes/stem, internode shape, internode length, girth of stem, root band width and brix (%). These characteristics were compared with those of the source plant. The salt tolerant somaclones performed better in characteristics of the sett germination, no. of tillers/plant, stem height, no. of nodes/stem and root band width with a variability (%) of 20, 50, 8, 33, and 14.3 respectively. There was no difference in the length of internode. The shape of internode was entirely different. The somaclones performed less in the characteristics of girth of stem and brix (%) with a variability (%) of 12.5 and 5.2 respectively. Multiplication of salt tolerant somaclones developed through tissue culture technology is at hand for further study.