Controlled deterioration and accelerated aging tests to estimate the relative storage potential of cucurbit seed lots

Abstract

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.