Effect of sulphur nutrition on pungency and storage life of short day onion (Allium cepa)

Abstract

A field experiment was carried out to evaluate the effect of sulphur nutrition at 0, 7.5, 10, 20, 30, 40 and 50 kg S/ha on pyruvic acid and storage life of onion bulbs in Vertic Haplustepts. Besides that, the effect of sulphur nutrition on soil available sulphur level, marketable bulb yield and sulphur uptake were also assessed. The results of this study revealed that sulphur application increased marketable bulb yield, sulphur uptake and pungency level over no sulphur treatment. Moreover the increase in bulb yield and sulphur uptake was less with increasing the sulphur level beyond 20 kg/ ha. The pyruvic acid content had significant and positive correlation with sulphur application (r 2 =0.735**). Sulphur application did not influence the storage life of onion bulbs significantly and showed no significant correlation with total storage losses of onion bulbs (r 2 = -0.0828). Soil sulphur level after harvest was increased over the initial values with application of sulphur @ 30, 40 and 50 kg S/ha while application of 7.5 kg S/ha and control without sulphur reduced soil available sulphur content. From this study, we conclude that sulfur nutrition is essential for increasing the onion yield and pungency level in soils having sufficient sulphur. However, excess sulphur application did not influence the yield and pungency level significantly. The storage life of onion bulbs were not influenced significantly by sulphur nutrition and application of either low or higher sulphur is detrimental to soil health.