Standardization of seed drying of ash gourd cv. Kashi Dhawal with zeolite beads and silica gel

Abstract

Ash gourd cv. Kashi Dhawal seeds are harvested during November-December of every year in northern part of India. Bringing down the seed moisture content to safer level by sun drying is a difficult task during this period. Use of seed dryer may affect the viability due to temperature fluctuation at the time of drying. Zeolite beads (aluminum silicate) and silica gel are desiccants, which can be utilized to dry the seeds. To standardize the drying method, seeds were mixed with Zeolite beads and Silica gel, separately, in the ratio of 1:0.5, 1:1, 1:2 and 1:3 (seed: desiccant, by weight) in an air tight container and kept at room temperature. Initial moisture content of seeds (9.02%) was estimated by hot air oven method. Seeds were separated from desiccant and weighed after 24h, 48h, 72h, 96h and 120h of drying. Weight of desiccants were also noted down at every 24h interval. At the end of the experiment final moisture content of dried seeds were estimated. It was observed that seed drying with zeolite beads was faster than silica gel. Significantly higher moisture content was removed from seeds (5.19%) within 24h by zeolite beads in 1:3 ratio. Final moisture content of seeds dried with zeolite beads reached 2.8% in 1:3 ratio and 6.48% in 1:0.5 ratio of drying condition after 120h of drying. In all the treatments, maximum moisture content from seeds was removed within first 24h of drying. Gradual increase in weight of desiccants indicate continuous removal of moisture from the seeds during drying period. Since, dormancy is a problem in freshly harvested ash gourd seeds, Tetrazolium test was conducted to know the viability of seeds. Quick viability test reveals on par seed viability (more than 80%) in all drying conditions and non-dried control. Further work is necessary to know the storability of ultra-dried seeds under air tight condition.