Improving nutrient use efficiency by exploiting genetic diversity of potato

Three separate field experiments were conducted to compare the nutrient efficiency indices, AUE (agronomic use efficiency), PUE (physiological use efficiency) and NUE (nutrient uptake efficiency) of ten Indian potato cultivars for the identification of nutrient efficient cultivars. Results showed wide variation in the nutrient efficiency of different potato cultivars. Kufri Pukhraj was the most N, P and K efficient cultivar among ten cultivars tested in the absence as well as presence of green manure. The efficient cultivars gave higher tuber yield under N, P and K stress (i.e with less dose of N, P and K fertilizer) and had higher AUE than less efficient cultivars. Mean AUE of N of different cultivars varied between 62 and 97 kg tubers/kg N without green manure and between 68 and 100 kg tubers/kg N with green manure. Mean agronomic use efficiency of Kufri Pukhraj was 97 and 100 kg tubers per kg N without and with green manure, respectively which was significantly higher than all other cultivars The main cause of higher nitrogen efficiency in the presence of green manure was the capacity of a genotype to use/absorb more N per unit green manured soil i.e. the ability of the root system of a genotype to acquire more N from green manured soil (NUE). Most P efficient cv. K. Pukhraj produced yield of 300 q/ha without P whereas K. Badshah and K. Ashoka needed 100 kg P2O5/ha to produce yield of 270 and 304 q/ha, respectively in the same field. Similarly most K efficient cv. K. Pukhraj produced yield of 364 q/ha without K whereas K. Badshah and K. Sutlej needed 80 kg K2O/ha to produce yield of 361 and 370 q/ha, respectively in the same field. The variation in phosphorus and potassium efficiency of different potato cultivars was due to both their capability to use absorbed P and K to produce potato tubers (PUE) and to their capacity to take up more P and K per unit soil (NUE).