Seed Treatment Effects on Emergence of Luffa Sponge Gourd

Luffa sponge gourd (Luffa aegyptiaca Mill.; also L. cylindrica) belongs to the Cucurbitaceae along with squash and pumpkin (Cucurbita spp.), gourd (Cucurbita spp., Lagenaria spp.), melon (Cucumis melo L.), and cucumber (Cucumis sativus L.). It is an annual climbing vine with tendrils, growing primarily in tropical and subtropical regions. The seeds are flat, smooth, and black or white (11). This species has been cultivated since ancient times in the far east and the Indian subcontinent, and has since been introduced to the Middle-east and Africa, and more recently into the Americas. The fruit is harvested at an immature stage (both fruit and seeds are soft), and is eaten as a cooked vegetable (prepared like summer squash). In most countries, it is cultivated in small plots in family gardens, usually for domestic consumption, with commercial cultivation being of secondary importance. However, it is beginning to appear in the international market place (6, 7). Germination percentages of several vegetable species have been shown to increase after seed treatment with chemicals and various osmotica (1, 4, 10, 13, 18). Luffa seed germination has been reported to be slow and sporadic (2). Low percentage of seed germination is a major problem in establishing a luffa crop, with typical rates of less than 75% (17). The seeds of many species of cucurbits are nonendospermic and germination is epigeal. Dormancy can be severe problem in some cucurbit species. It is comparatively easy to induce dormancy by testing the seeds for germination in unfavorable environments. In particular, the germination test substrate should not be too moist and only very low intensity light treatments should be applied. In most cases, it is probably best to perform seed germination tests in darkness. Successful dormancy-breaking treatments in sponge gourd are observed to be use of constant temperatures with optimum range of 30 to 35°C, scarification of the seeds before germination, cracking the seed coat before germination, and use of moist sand for the germination medium.