RESISTANCE TO GAS DIFFUSION THROUGH THE SEEDCOAT AND HILUM OF WATERMELON (CITRULLUS LANATUS MATSUM NAKAI)

摘要

Recent research has proposed that gas diffusion through the seedcoat of triploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] maybe a significant limiting factor to germination. A method for determining resistance to gas diffusion through the seedcoat and hilum of watermelon seed was developed to compare a diploid ('Ferrari') and a triploid ('Genesis') watermelon. By measuring ethane diffusion in a specialized apparatus, resistance was calculated for the two cultivars using equations derived from Fick's first law of diffusion. Mean resistance to ethane diffusion through the seedcoat of 'Genesis' and 'Ferrari' was found to be 711 and 443 s cm~(-1), respectively. Resistance to diffusion means through the hilum for 'Genesis' and 'Ferrari' were 1022 and 481 s cm~(-1) on a per hilum basis, respectively. Difference in resistance coefficients was attributed to difference in seedcoat thickness between the cultivars. The method developed should be useful in basic comparison of gas diffusion through seedcoats under test conditions.