Productivity performance of Phulkara onion under different NPK regimes with stoppage of P and K

The present investigation was performed to evaluate the productivity performance of Phulkara onion under different NPK regimes and to see the effects in case P or K is stopped, at Sindh Agriculture University, Tandojam during 1999-2000. The experiment was laid out in randomized complete block design replicated three times. Each replicate comprised of six sub-plot units to test the influence of the following N.P.K. fertilizer combination levels on the onion variety Phulkara. The observations were recorded on different growth and yield contributing parameters viz., plant height, number of leaves per plant, horizontal and vertical bulb diameter, single bulb weight, bulb yield per plot and per hectare. The experiment was comprised of six N.P.K fertilizer levels including a control. The growth parameters were measured at various growth stages, while the yield attributes were measured after harvest of the onion bulbs. The maximum plant height (42.33 cm) was recorded in the plots received 100-80-75 kg NPK per hectare followed by 41.33 cm under the same NP level but no K (100-80-00 kg NPK/ha). The minimum plant height of 27 cm was obtained when crop was fertilized with 50 kg N, 45 kg K and no P. Statistically the differences were highly significant (P less than 0.01). The highest number of leaves (9.18) was obtained when the plots received 100-80-75 kg NPK per hectare, followed by 9.09 leaves per plant under the same NP level but no K (100-80-00 kg NPK/ha). The minimum number of leaves 7.12 was obtained when crop was fertilized with 50 kg N, 45 kg K and no P. statistically the differences were highly significant for this component. The maximum horizontal diameter of bulb (7.77 cm) was recorded from the plots fertilized with 100-80-75 kg NPK per hectare closely followed by 7.69 cm under the same fern-lily level except absence of K (100-80-00 kg NPK/ha). No greater differences were noted between above two levels. The lowest horizontal diameter 6.07 cm was obtained when was fertilized with 50 kg N, 45 kg K and no P. Overall tire results for this parameter were highly significant. The maximum vertical diameter of bulb (6.63 cm) was recorded from the plots fertilized with 100-80-75 kg NPK per hectare, arid the diameter reduced slightly (6.62 cm) under the same fertility level except absence of K followed by 75-60-00 kg NPK per hectare with 6.18 cm vertical diameter, and the minimum vertical diameter 5.06 cm was recorded when crop was fertilized with 5o kg N, 45 kg K and no P. The highest single bulb weight (120 g) was recorded from the plots fertilized with 100-80-75 kg NPK per hectare, and the single bulb weight slightly reduced (1.16.33 g) under titre same fertilizer regime except absence of K (100-80-00 kg NPK/ha). While, The lowest single bulb weight 19 g was recorded when crop was fertilized with 50 kg N, 45 kg K and no P. Statistically the differences were high significant. The highest bulb yield (48.67 kg) was obtained from the plots fertilized with 100-80-75 kg NPK per hectare, and the bulb yield was reduced a little (47.98 kg) under the same fertilizer regime without K (100-80-00 kg NPK/tea). The lowest bulb yield 29.20 kg was recorded when crop was fertilized with 50 kg N, 45 kg K and no P. The results were statistically highly significant. The highest bulb yield (23.177 m.t) per hectare was achieved from the plots treated with 100-80-75 kg NPK per hectare, and the bulb yield was reduced a little (22.848 m.t) under the same fertilizer regime but absence of K (100-80-00 kg NPK/ha). The lowest bulb yield 13.907 m.t per hectare was recorded when crop was fertilized with 50 kg N, 45 kg K and no P. The results further explained that as the N levels increased, there were a significant increase in bulb yield, but as in the case of other parameters, diameter reduced slightly when P or K were applied with N because differences between the treatments having same N levels but varying or absence of P and K were statistically non- significant. After exploring the results of the present investigation, it could be presumed that nitrogen alongwith P and K is vital constituent for plant growth and satisfactory final produce of any crop. However, the present study envisaged that each increase in N.P.K levels, recorded rapid improvement in growth and bulb yield attributes of onion. However, in case of absence of P or K, the crop had little adverse effects, but no significant economical loss was observed.