Effect of seed invigoration by osmo-conditioning on radicle emergence and physiological parameters of the true seed of shallot (Allium ascalonicum L.)

Seed deterioration resulting from production and storage factors is the major cause of differences in the seed vigour that results in low seedling emergence in both the laboratory and in the field. An experiment was conducted to evaluate the effect of seed invigoration by osmo-conditioning on the radicle emergence and the physiological parameters of naturally deteriorated seed lots of the true seed of shallots. The experiments were arranged in a completely randomised design with a repeated measurement for radicle emergence and a randomised complete block design for seedling vigour in the field with four replicates. The results indicated that the radicle emergence of the invigorated seed with ZnSO4 correlated well with the seed viability and vigour parameters for seed lots stored under uncontrolled conditions. The radicle emergence of invigorated seeds stored under the uncontrolled condition were more predictive and strongly correlated with the seedling vigour parameters in the field, i.e., the field emergence, field emergence rate and mean emergence time with r = 0.968, r = 0.970 and r = -0.947, respectively. Furthermore, the coefficients of determination were significant (P < 0.05) with R2 = 0.936 field emergence, R2 = 0.941 field emergence rate and R2 = 0.898 for the mean emergence time. Seed invigoration with 0.5% ZnSO4 further significantly reduced the time of a single count of RE from 72 hours and 68 hours to 60 hours with field prediction rates ranging from 90-99%. It was concluded that the radicle emergence of TSS can be improved by invigorating the seeds with 0.5% ZnSO4 thereby increasing the germination percentage, vigour index, and germination rate and reducing the mean germination time.