Effects of in vitro and Greenhouse Application of Soluble Chitosan on Growth and Minituber Yield of Potato Plantlets

In order to investigate the effect of soluble chitosan on plantlets growth in vitro and minituber yield in potato micropropagation، single node plantlets of Agria cultivar were treated in vitro with soluble chitosan at different concentrations including 0، 5، 15، 50، 150 and 500 mg l-1 by adding to the tissue culture medium and growth parameters of plantlets were assessed in vitro. A number of plantlets were subsequently transferred to the greenhouse and sprayed with chitosan solutions including 0، 200، 400، 600، 800 and 1000 mg l-1 weekly، and minituber yield recorded. The results showed that the effect of chitosan was significant on fresh and dry weights of shoot and root and length of plantlets، but its effect on leaf number per plantlet was insignificant. Application of chitosan at concentration of 500 mg l-1 significantly increased the shoot fresh and dry weights، compared to the control. However، at low concentrations its effect was insignificant. The 15 mg l-1 of soluble chitosan significantly led to the increase in root fresh weight of in vitro plantlets. Whereas، higher concentrations، especially 500 mg l-1، significantly decreased root fresh weight of in vitro plantlets without considerable decrease in root dry weight. In vitro application of 500 mg l-1 chitosan significantly resulted in improved acclimatization of plantlets in the greenhouse as expressed by increasing minituber numbers and yields، compared to the control. However، foliar chitosan application at the greenhouse did not show significant effect on yield parameters. The present results indicate that soluble chitosan can be successfully incorporated into potato seed production from in vitro plantlet stage.