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    Changes in germination and potential longevity of watermelon (Citrullus lanatus) seeds during development
    (Taylor & Francis Ltd, 2004) Demir, I; Mavi, K; Oztokat, C
    Changes in germination and potential seed longevity (K-i of the viability equation) were monitored during the development of watermelon (Citrullus lanatus) seeds grown in warm (minimum and maximum temperatures were 16.8 and 40.1degreesC) and cool (9.8 and 35.1degreesC) sites in 2002. Maximum seed weight (mass maturity, end of seed filling phase) was attained 25 days after anthesis (DAA) under both growing conditions. However, maximum germination was observed at 30 DAA in both sites. Potential seed longevity was achieved at 45 and 40 DAA, which were 20 and 15 days after mass maturity (the time of maximum seed dry weight) in warm and cool sites, respectively. When the maximum quality was achieved, fruit flesh was pale red, red, and 98-100% of the seeds were brown coloured. Seed dry mass and maximum potential longevity were consistently greater in cool than in warm growing sites. Dried seeds had higher germination percentages than those of fresh ones until mass maturity (25 DAA) at both sites.
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    Öğe
    Effect of salt priming on germination and seedling growth at low temperatures in watermelon seeds during development
    (Ista, 2003) Demir, I; Oztokat, C
    The effect of salt priming (KNO3, 20degreesC, 3%, 6 d) on germination at seven and 14 days after planting and on root and shoot lengths of watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai) seed lots harvested at a range of intervals from anthesis and at two levels of temperature was investigated during the years 2000 and 2001. Untreated seeds of 15, 20, 25 and 30 DAA (days after anthesis) were unable to germinate and final germination was lower than 20% in subsequent harvests until 60 DAA at 14degreesC. While at the same temperature treated seeds had germinated as early as 20 DAA and reached to 66% and 51% in 40 (2000) and 35 DAA ( 2001), respectively. Germinated seeds were unable to grow shoots at 14degreesC in either year. At 18degreesC, treatment was not effective on germination percentages at day seven in all three lots in 2000 but improved root and shoot lengths. The advantage obtained from the treatment varied among the lots with a minimum benefit of an increase of 15 mm in root and 28 mm in shoot length, respectively. Priming increased germination percentages at day seven and final and root and shoot length of all seed lots in 2001. Germination percentages in treated seeds varied between 68% and 84% in seeds harvested 20 DAA and thereafter. The less mature the seeds the higher the benefit obtained from the treatment. Maximum root and shoot lengths were recorded in seeds of 35 DAA as 37 and 40 mm in the control and as 60 and 61 mm in treated, respectively. We concluded that salt priming can be useful for improving germination, seedling growth and uniformity of heterogeneously matured watermelon lots at low temperatures to produce well developed seedlings in early spring sowings.