EFFECT OF POTASSIUM APPLICATION RATES AND VARIETIES ON GROWTH AND SEED YIELD OF ONION
Department of Horticulture, Sindh Agriculture University, Tandojam, Pakistan
Keywords:potassium rates, onion varieties, seed yield
Although, potassium is one of the essential macronutrients for plants; majority of our onion growers in Sindh province prefer to apply only nitrogen and phosphorus and avoid applying potassium fertilizers in their onion fields; which not only stunts crop growth, but it deteriorates the quality of onion seed; mainly used by farmers for cultivation of next season crop. In order to investigate the effect of potassium application rates on growth and seed quality; we conducted a field experiment during the winter season of 2017-18, applied potassium fertilizer (SoP) @ K1: 0, K2 : 25, K3 50, K4 : 75, K5 100 and K6 125 kg K2O ha-1 to three most common local onion varieties, viz., Phulkara, Nasarpuri and Thano Bolakhan. The study was conducted at Horticultural Garden, Sindh Agriculture University Tandojam, Hyderabad. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three repeats. It was observed from the experiment that among the six potassium application rates included in the study; the potassium applied @ 100 kg K2O ha-1 (K5) remained more positively effective for seed quality traits including days to 50% bolting, flowering and maturity, flower stalk height, number of seeds umbel-1, seed index and per hectare seed yield. Averaging overall potassium application rate treatments we found that Phulkara variety took fewer days to 50% bolting, gave more seed yield (g umbel-1) and displayed maximum seed index; whereas variety Nasarpuri took fewer days to both 50% flowering and 50% maturity, showed tallest flower stalk, gave more seeds umbel-1 and produced higher per hectare seed yield as well.