Synergistic effect of key inputs (irrigation and nutrients) on physiological behaviors and yield of upland cotton (Gossypium hirsutum L.)
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Abstract
In order to determine the synergistic effects of key inputs (Irrigation and nutrients) on physiological behaviors and seed cotton yield of cotton, the experiments were conducted for consecutive two years (2017 and 2018). The data for both the years was pooled and effects were determined from the average data. The existing recommended dose of fertilizers (RDF) 112-56-56 kg ha-1 (T2) was kept as control to investigate the crop response to 10% increase over RDF (T1=124-62-62 kg ha-1) and 10% decrease over RDF (T3=100-50-50 kg ha-1). These NPK rates were applied in integration with varied irrigation frequency such as: 7 irrigations (30, 45, 60, 75, 90, 105, 120 DAS); 6 irrigations (30, 50, 70, 90, 110, 130 DAS [existing recommendation] and 5 irrigations (30, 55, 80, 105, 130 DAS). The results showed that seed cotton yield plant-1 and its allied traits were significantly (P<0.05) affected by the interactive effect of NPK levels and irrigation frequency. The interaction of 124-62-62 kg ha-1 NPK × 7 irrigations resulted in slightly higher seed cotton yield plant-1 (141.46 g); closely followed by yield of 139.80 g and 139.44 g plant-1 achieved in the interactive effect of NPK at 124-62-62 kg ha-1 × 6 irrigations and 124-62-62 × 5 irrigations, respectively. Although, treatment interaction 124-62-62 kg ha-1 NPK × 7 irrigations had slight edge for seed cotton yield plant-1 over rest of the treatment interactions; but statistically the difference amongst 7, 6 or 5 irrigations under 124-62-62 kg ha-1 NPK were insignificant (P>0.05); suggesting that irrigating crop 7 or 6 times was uneconomical regardless of NPK application. Hence, interaction of NPK @124-62-62 kg ha-1 × 5 irrigations would be optimum combination to achieve economical seed cotton, seed and lint yields. However, all the physiological traits showed markedly greater values under the interaction of 124-62-62 kg ha-1 NPK × 7 irrigation suggestive of excessive plant growth, swelling foliage, but all these had adverse effect on seed-cotton, seed and lint yield.
Keywords: Cotton; Interactive effect NPK; Irrigation frequency; Yields, Physiological behavior