The laboratory germination (radicle emergence) percentages of 9 watermelon, 12 melon, and 7 cucumber seed lots were tested after storing in relatively adverse storage conditions of 25 °C and 12% mc for 6, 12, and 18 months in sealed aluminum foil packets. The laboratory germination (radicle emergence) of lots was determined after controlled deterioration (CD) at 45 °C with 20% or 24% moisture content (mc) for 48, 72, 96, 120, and 144 h. The accelerated aging test (AA) was conducted at 45 °C for the same aging periods. A number of seed lots was dead by 12 and 18 months in watermelon and cucumber, respectively. Various combinations of test regimens were found to be correlated with laboratory germination after 6 months storage, but the most consistent regimens for AA tests was 96 h at 45 °C in all species (r = 0.71 to 0.98). In the CD tests, 72 h with 20% mc at 45 °C gave the best correlation (r = 0.86 to 0.96). These conditions of highest correlation were observed after laboratory germination after 6 months storage and are suggested as good predictors of storage life in cucurbit seed lots. The initial standard germination before storage was also significantly correlated with seed longevity, but the correlation coefficient was generally lower (r = 0.60 to 0.83) than the AA and CD test results and separation of lots less clear.
Kazim Mavi and Ibrahim Demir
The emergence of 22 commercial seed lots (12 in 2005 and 10 in 2006) of melon (Cucumis melo L.) with laboratory germinations greater than 90% were compared in low temperature (LTE), mechanical stress (MSE), high temperature (HTE), and salt stress (SSE) sowing conditions. The seedling emergence percentage ranged between 18% and 79% for LTE, 15% and 90% for MSE, 27% and 84% for HTE, and 49% and 92% for SSE in 2005; and 43% and 85% for LTE, 30% and 82% for MSE, 56% and 91% for HTE, and 49% and 89% for SSE in 2006. The germination of the lots was determined after controlled deterioration (CD) with 20% or 24% moisture content (MC) and accelerated aging (AA) at 40 and 45 °C in 2005; or at 45 and 47 °C in 2006 for 48, 72, 96, 120, and 144 h. Germination after various combinations of CD and AA was positively and significantly (P < 0.05) correlated with LTE, MSE, HTE, and SSE. Correlation values (0.17 to 0.78) of the initial laboratory germination were much lower than those of both aging tests. The optimum CD conditions of 48 h and 20% MC at 45 °C and AA conditions of 120 h at 45 to 47 °C are suggested as vigor tests to estimate relative seedling emergence of melon seeds.
Burcu Begüm Kenanoglu, Ibrahim Demir, and Henk Jalink
This work was conducted to investigate the efficacy of chlorophyll fluorescence (CF) sorting to improve seed germination, seedling emergence, and vigor of seeds produced from different maturity fruits of four different cultivars. Four harvest dates from each cultivar were evaluated by harvesting orange (immature), bright red (half-mature), dark red (mature), and dark red and soft (overmature) fruits. Seeds were either sorted or nonsorted after harvesting and standard laboratory germination, seedling emergence, and controlled deterioration tests were conducted. CF sorting significantly increased laboratory germination, seedling emergence, and seed vigor. Maximum improvements were obtained from seeds harvested from half-mature and mature stages. Mean germination improvement among cultivars between CF-sorted and nonsorted seeds were 14% in the immature seeds, 11% in half-mature seeds, 6% in mature seeds, and 9% in overmature seeds. Improvements in seedling emergence were 21%, 17%, 9%, and 10% and 4%, 11%, 10%, 14% for seed vigor (CD germination) in the all maturity stages of seed lots, respectively. CF has the potential to upgrade seed quality in pepper lots as a non-destructive sorting technology.
Ibrahim Demir, Tuba Celikkol, Golge Sarıkamıs, and Ceren Eksi
A study was made of the relationship among accelerated aging (AA), saturated salt accelerated aging (SSAA), mean germination time and second day germination percentage vigor tests, and seedling emergence and longevity storage at 5 and 25 °C for 6 and 12 months. Initial germination was above 80% for all seed lots. Seedling emergence values varied between 21% and 94% and mean emergence time between 6.5 and 11.0 days among seed lots. The SSAA test correlated with emergence better than the AA test. All combinations of SSAA temperatures (41, 43, and 45 °C for 72 h) were correlated to emergence (r = 0.95 to 0.98, P < 0.001) and emergence rate (r = 0.90 to 0.94, P < 0.001). Seed germination after 6 months of storage ranged between 21% and 98% at 5 °C and 26% and 100% at 25 °C. Corresponding values were 19% and 98% and 15% and 89% after 12 months. All combinations of AA and SSAA were related to longevity of seed lots, but significance for SSAA was higher (above P < 0.01) than AA (P < 0.05). In both tests, a higher aging temperature reduced the significance level. Mean germination time and second day germination percentages also predicted seedling emergence and longevity (P < 0.05 in all cases). Standard germination percentages were successful in predicting seedling emergence (P < 0.05), but with one exception failed to predict (P > 0.05) longevity in viola seed lots. In conclusion, although both aging tests successfully differentiated seed quality, SSAA test results better predict emergence and longevity of viola seed lots.
Ibrahim Demir, B. Begüm Kenanoglu, Kazim Mavi, Tuba Celikkol, Fiona Hay, and Zeliha Sariyildiz
The effect of moisture on seed longevity during experimental storage was investigated in pepper (Capsicum annuum) cultivar Demre. Seeds were stored hermetically at 7.0%, 8.6%, 9.5%, 10.5%, and 12.1% moisture content (MC; percent fresh weight basis) and 35 °C for up to 306 d. Viability (normal germination) was assessed periodically and the seed viability equation moisture constants, K E and C W, estimated by regression of log σ (the sd of distribution of seed death in time) with log MC. K E and C W values were found to be 7.767 and 4.670, respectively. The newly found moisture constants were combined with the temperature constants that had already been proposed as universal for all orthodox seeds (C H = 0.0329, C Q = 0.000478) and their validity was tested by predicting the viability loss in another pepper cultivar, Carliston. The K i of the Carliston cultivar was determined by controlled deterioration at 40 °C and 14% MC. The observed viability loss between 30 and 270 d at 25 °C and 10% seed MC was closely related to that predicted by the equation R2 = 0.982 (P < 0.001).