| dc.description.abstract | Seed vigour is one of the seed parameters that determines the quality of seed for successful crop production. Looking into the complexity of the situation, the ISTA congress of 1995 adopted the definition of seed vigour as "the sum total of those properties of the seed which determine the level of activity and performance of the seed or seed lot during germination and seedling emergence". Seed deterioration resulting from production and storage factors are the major cause of the differences in seed vigour that results in low seedling emergence in both the laboratory and in the field, hence a loss in seed vigour
The experiment was conducted at IPB University (Bogor Agricultural University) to develop a seed vigour testing method for the true seed of shallots (TSS) using single counts of radicle emergence (RE) that can be used to estimate and predict the germination percentage of normal seedlings in the laboratory and field emergence. The research was conducted in three phases with experiment 1; determination of a single count for RE, experiment 2 was done to verify the RE method on naturally deteriorated seed stored under two different conditions for a period of 6 months, and experiment 3 was done to improve RE through seed invigoration.
TSS of two varieties were used in this study i.e. Bima and Trisula harvested on 4th and 10th October 2018 cropping season respectively. Four seed lots from Trisula and five seed lots from Bima were artificially made by exposing the seeds to accelerated aging treatment and used in experiment 1. The second and third experiment used Trisula (92.0% germination), harvested on 3rd November 2018. Seed lots were artificially made which consisted of nine seed lots for experiment 1. Seed lots were germinated at two different temperatures i.e. 20±1℃ and 25±1℃. The experiments were arranged in a completely randomized design (CRD) with a repeated measurement for RE and randomized complete block design (RCBD) for seedling vigour in the field with four replicates.
Results showed that a single count of RE at 68 or 72 hours for seed lots germinated at 20±1℃ or 25±1℃ respectively were able to predict germination percentage in the laboratory 12 days after sowing and field emergence 14 days after sowing. Regression and correlation analysis values for a single count of RE were predictive to germination percentage with r = 0.891 and R 2 = 0.951 for seed lots germinated at 20±1℃ or r = 0.924 and R2 = 0.875 for seed lots germinated at 25±1℃ which were all significant. RE further predicted mean germination time (MGT) r = -0.543 and R2 = 0.801 (p < 0.05) for seed lots germinated at 20±1℃ or r = -0.818 and R2 = -0.553 for seed lots germinated at 25±1℃. Furthermore, RE was predictive to field emergence (FE %) with r = 0.953 and R2 = 0.909 (p<0.05) and r = 0.865 and R2 = 0.732 (p<0.01) for seed lots germinated at 20±1℃ or 25±1℃ respectively.
Results further indicated that RE was able to separate seed lots of TSS that deteriorated naturally for a period of six months. RE predicted seed vigour parameters in the laboratory and seedling vigour in the field for naturally deteriorated seed lots confirming that the newly developed method was very effective. A single count of RE
at 72 hours was predictive to seedling vigour in the field for naturally deteriorated seed lots with R2 = 0.953, R2 = 0.913 and R2 = 0.955 for field emergence, mean emergence time and field emergence rate respectively. High correlation coefficients and coefficient of determination between RE and seed vigour parameters in the laboratory and seedling vigour in the field provided adequate evidence that a single count of RE was effective in predicting other seed vigour parameters for TSS.
Invigoration of TSS with ZnSO4 was better than other osmoconditioning treatments which increased germination percentage, vigour index, germination rate and reduced MGT. The RE of the ZnSO4 invigorated seed correlated well with these seed viability and vigour parameters for seed lots stored under uncontrolled condition. Seed invigoration with 0.5% ZnSO4 significantly reduced the time of a single count of RE from 72h and 68h to 60 hours with field prediction rate ranging from 90-99%. Since a single count of RE correlated well with other seed vigour parameters and seedling vigour in the field, therefore a single count of RE at 68 or 72 hours can be used as one of the methods for seed vigour tests of TSS. | id |
