Effect of potassium through polyhalite on growth and yield of onion Var. CO(ON) 6

Plants require nutrients to grow, so polyhalite is utilized as a natural fertilizer. Its reduced carbon footprint makes it useful in organic farming as well. Because of this context, A field experiment was carried out at the farmer's field in Mattiyampatti village, Dharmapuri district, Tamil Nadu, to evaluate the effect of polyhalite as a potassium source on growth yield parameters of onion using CO(on)6 variety as a test crop during 2022-2023. The experimental soil was sandy loam in texture (Typic Ustropept) with pH of 7.56 and EC of 0.24 dS m-1. The experiment was laid out in randomized block design consisting of twelve treatments and three replications. The recommended dose of nitrogen (60 kg ha-1) and phosphorus (60 kg ha-1) were applied as urea and single super phosphate, respectively. The polyhalite and muriate of potash were used as a potassium source at different levels (10 to 50 kg K2O ha-1) per the treatment schedule. The present study revealed that polyhalite application performed better than muriate potash in all parameters. With respect to the level of applications 40 kg K2O ha-1 as polyhalite registered the maximum growth attributes such as plant height (66.4 cm), number of leaves per plant (34.3), root length (9.63 cm), number of tillers plant-1 (4.78) and chlorophyll content (59.3 SPAD readings), and yield attributes such as number of bulb plant-1 (6.64), single bulb weight (9.69 g), bulb length (4.00 g), neck diameter (3.94 g) and neck thickness (13.82 mm). The minimum responses were observed in absolute control.