Journal of Taiwan Agricultural Research

Author:Yi-Jing Chen, Chwen-Ming Yang, and Kai-Ying Chiu*

Abstract:

The purpose of this study was to investigate the differences in germination behavior of rootstock-type eggplant varieties ‘A105’ and ‘A108’ at 15℃ , including germination percentage, mean germination time, water absorption, leakage electrical conductivity and soluble protein content inside the seeds, as well as changes caused by high-voltage electrostatic field (HVEF) treatments. The results showed that there were differences between the two eggplant varieties in the above-mentioned traits, and the treatments with HVEF changed the germination behavior of the seeds. After seeds were treated with HVEF at 0.5 kV cm^-1 for 600 s, the germination percentage of the ‘A105’ variety increased from 94.67% to 100%, and the mean germination time was significantly shortened from 7.86 d to 6.48 d after being treated with 10.0 kV cm^-1 for 600 s. The water absorption showed a second wave of rapid water absorption after 72 h of imbibition. The leakage electrical conductivity value was significantly higher than that of the control check (CK) after treatment at 0.5 kV cm^-1 for 60–600 s. The soluble protein content in the seeds of CK was lower than that of the HVEF treated seeds, indicating that HVEF treatments could rapidly induce the increase of the soluble protein content to the maximum on the first day. The germination percentage of variety ‘A108’ was greatly increased from 44.67% to 93.33% after being treated at 1.0 kV cm^-1 for 60 s. The mean germination time was significantly shortened from 11.92 d to 10.82 d. The water absorption reached saturation 12 h after imbibition, and the second wave of rapid water absorption occurred until 120 h. Regardless of CK or treated seeds, the leakage electrical conductivity was the highest at 6–8 h after imbibition, and then began to decrease. With 0.5 kV cm^-1 and 1.0 kV cm^-1 treatments, the leakage electrical conductivities were lower than those of CK. Increasing the strength of HVEF did not significantly increase the conductivity. The soluble protein content in the seeds of CK was lower than that of the treated seeds from Day 0 to Day 3, and did not increase significantly until Day 5. Photographs taken by scanning electron microscope (SEM) revealed the differences in the thickness and microstructure of the seed coat of the two varieties. The microstructure of the seed coat of variety ‘A105’ was relatively loose with obvious cracks, while the seed coat of ‘A108’ was relatively dense with small cracks. Based on the experimental results, it is tempting to speculate that the differences in seed coat thickness and tissue microstructure may contribute to the inconsistent germination traits of the tested eggplant varieties, which indirectly affect the physiological processes and germination behavior of the seeds. In the case of inferior seed germination performance such as eggplant variety ‘A108’, using an appropriate HVEF treatment, it could effectively increase germination percentage, water absorption and leakage electrical conductivity, shorten the mean germination time, and promote the early induction of soluble protein content in the seed, and then greatly improves the germination performance of the seeds.

Key words:Eggplant seed, Germination percentage, Mean germination time, Leakage conductivity, High-voltage electrostatic field

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