Evaluation of potato cultivars for phosphorus efficiency under Nilgiris conditions

Field experiments were conducted at ICAR-Central Potato Research Station, Muthorai, the Nilgiris, Tamil Nadu for three years with seven potato varieties under four levels of phosphorus to evaluate its efficiency. Varieties Kufri Neelima and Kufri Swarna were found more P efficient because of their higher relative biomass production, tuber yield efficiency index, harvest index, agronomic use efficiency (AUE) and P uptake efficiency. These two varieties produced higher tuber yields under no P and at P-max of standard variety. The varieties Kufri Girdhari, Kufri Jyoti and Kufri Himalini proved P responsive as they responded well to P application and produced very low yields under no P application. Higher root biomass in these two efficient varieties could be the reason behind their higher P use efficiency as compared with other genotypes. The two P efficient potato varieties also happen to be resistant to potato cyst nematodes, which is very common and serious problem in the Nilgiris. The mechanism to have resistance against PCN, whose cysts emerge only in the presence of root exudates of susceptible potato varieties, could also have benefitted those cultivars to show more efficiency in native P utilization. Further investigations are required to find out the exact mechanism of P efficiency in these two PCN resistant genotypes.