Evaluation of potato (Solanum tuberosum) cultivars for productivity, nitrogen requirement and eco-friendly indices under different nitrogen levels

A field experiment was conducted during the winter (rabi) seasons of 2011–12 and 2012–13 at Adisaptagram Block Seed Farm, Hooghly, West Bengal, to optimize the potato (Solanum tuberosum L.) cultivars and nitrogen levels for growth attributes, tuber yield, nitrogen-use efficiency, sustainability, eco-friendliness and economics in new alluvial zone of West Bengal. Fifteen treatment combinations, viz. 3 potato cultivars (‘Kufri Himalini’, ‘Kufri Shailja’ and ‘Kufri Jyoti’) and 5 N doses (0, 75, 150, 225 and 300 kg N/ha) were laid out in a factorial randomized block design with 4 replications. ‘Kufri Himalini’ recorded the maximum tuber yield (31.3 t/ha), which was significantly higher than ‘Kufri Shailja’ (26.6 t/ha) and ‘Kufri Jyoti’ (24.1 t/ha). Correlation between tuber yield and plant height (R²=0.73), tuber yield and dry matter accumulation (R²=0.84), tuber yield and tuber bulking rate (R²=0.75) and tuber yield and total N uptake (R²=0.62) were significant. The correlation study between nitrogen and tuber yield showed high degree of correlation (R²=0.984) and N_opt. was derived as 202.6 kg N/ha for optimum economic yield. Agronomic efficiency (AE_N) and physiological efficiency (PE_N) was more in ‘Kufri Himalini’ at all N levels. There was a positive balance of nitrogen in all the treatments except one treatment (‘Kufri Jyoti’ with 300 kg N/ha). ‘Kufri Himalini’ fertilized with 300 kg N/ha gave the highest net returns ( 1,45,156/ha) and benefit: cost ratio (2.58) with least difference from 225 kg N/ha, while the negative response was recorded in the control. ‘Kufri Shailja’ potato was more eco-friendly, as its index was 18.4% higher than ‘Kufri Jyoti’. ‘Kufri Shailja’ required 18.4% less application of fertilizer N to give the highest yield obtained by ‘Kufri Jyoti’ (30.94 t/ha). So, for obtaining a given yield, less amount of fertilizer is being put to soil and hence comparatively less amount of N is being lost to the environment.