Seed Production and Germinability of Cucurbit Crops

Cucurbit crops are mostly produced for their immature or mature fruits. However, a relatively high proportion of cucurbit fields are destined for seed production, either for seed consumption or for propagation material. Production of cucurbits for seed consumption (as a snack food) is very popular in some parts of the globe and almost unknown in others. Open-pollinated cultivars (inexpensive seeds) are used in almost all crops for seed consumption. In the last decades the proportion of hybrids has dramatically increased because of the advantages of heterosis, improved technology and utilization of controlled environments. Cucurbit crops are insect-pollinated, and the introduction of honey-bee colonies into cucurbit seed production fields is an essential step for success. However, isolation is required to prevent outcrossing, both for open-pollinated cultivars and hybrid cucurbit seeds. Understanding the role of phytohormones and growth regulators in sex expression of cucurbits has greatly facilitated hybrid seed production. The germination ability of cucurbit seeds is related both to external and internal factors. Variability in germination ability of any seed population harvested at a particular site during a given season is based on interand within-plant variations. The failure of cucurbit seeds to germinate may at times have no relation to seed quality but may also be due to the lack of specific requirements. This is probably the case in conditional dormancy which is typical for some cucurbits. Appropriate temperature is probably the most important factor, but gas exchange, water potential and hormones are also involved in regulating germination. Seed quality can be affected by the maternal environment, seed maturity at harvest, extraction procedure, and storage conditions. Priming treatments can improve germination, especially when applied to poor quality seeds, or under stressful environments. _____________________________________________________________________________________________________________