Effect of repeated harvest of sprout crops on the status of potato viruses x, s and y in Potato varieties

Studies were undertaken in six potato cultivars to evaluate the spread of PYX, PVS & PVY by testing different sprout crops with alkaline phosphatase double antibody sandwich Enzyme Linked Immunosorbent Assay (DAS-ELISA). The concentration of PYX and the number of infected samples increased with increasing the harvests of sprout crops in cvs, Kufri Chandramukhi, Kufri Badshah, Kufri Muthu and Kufri Lalima but in varieties Kufri Jyoti and Kufri Swama the increase was inconsistent. In case of PVS, the results were more inconsistent. Nevertheless the concentration of virus increased upto 3rd crop of sprout and then declined afterwards except in Kufri Chandramukhi and Kufri Muthu, where it increased upto last crop. An interesting trend in virus dilution was observed with PVY. In all the six varieties the concentration of virus was reduced in the range of 75 to 93.5 percent after 2nd harvest of sprouts. The studies indicated that spread of PYX and PVS increased with the repeated harvest of sprouts while PVY reduced after second harvest. These results are suggestive of the spread of contagious viruses and reduction of PVY in rapid multiplication programme, if not started with healthy seed tubers.