比較高壓靜電場不同強度及時間處理對不同品種砧木茄子種子之影響

Abstract

嫁接無性繁殖除了砧木與接穗之間的融合親合性議題之外，目前台灣在地茄子種苗產業關注的課題，尚包括如何改善砧木型種子在15℃低溫下出現的發芽行為差異性，裨益於種苗生長之管理。據此，本研究選用2 種砧木型茄子 ‘A105’ 與 ‘A108’ 品種種子，探討在15℃低溫環境下品種間發芽行為差異，包括發芽百分比、平均發芽時間、吸水率、滲漏電導度及種子內部可溶性蛋白質含量等性狀，以及利用高壓靜電場 (high-voltage electrostatic field; HVEF) 處理後造成之改變與改善效果。根據試驗結果，發現兩茄子品種在上述各性狀表現上存在品種間差異，以HVEF 處理將可以改變種子發芽性狀。其中，種子經過HVEF 0.5 kV cm-1 處理600 s後，‘A105’ 品種之種子發芽百分比由94.67% 增至100%，平均發芽時間以10.0 kV cm-1 處理600 s 後，由7.86 d 顯著縮短至6.48 d，吸水速率在浸潤72 h 後出現第二波快速吸水現象、而滲漏電導度值在0.5 kV cm-1 處理60–600 s 後，明顯高於對照組 (control check; CK)；種子內部可溶性蛋白質含量顯示出CK 含量低於處理組，而且經過電場處理後可以在第1 日即快速誘導可溶性蛋白質含量的增加到最大值。‘A108’ 品種種子發芽百分比經1.0 kV cm-1 60 s 處理，則由44.67% 大幅提升至93.33%，平均發芽時間由11.92 d 明顯縮短至10.82 d，吸水速率在浸潤後12 h 達到吸水飽和，直到120 h 出現第二波快速吸水現象，而滲漏電導度則無論CK 或處理組，其滲漏電導度值概在浸潤後的6–8 h 最高，隨後開始下降。以0.5 kV cm-1 與1.0 kV cm-1 處理，滲漏電導度值皆低於CK，增加HVEF 的強度並未顯著提高滲漏電導度值。種子內部可溶性蛋白質含量在CK第0–3 日之數值皆低於處理組，直至第5 日才有明顯的提升。另經由掃描式電子顯微鏡 (scanning electron microscope; SEM) 呈現兩品種在種皮厚度與顯微構造上之差異，‘A105’ 種子種皮顯微組織較為寬鬆，可以看到明顯裂縫，而 ‘A108’ 種子種皮顯微組織則相對較為緊密，裂縫微小。以HVEF 0.5 kV 600 s 強度處理後，兩品種的種皮開始出現構造上的改變，‘A105’ 種子種皮表面破洞明顯加劇，而 ‘A108’ 的種子種皮表面雖有種皮破裂，但沒有 ‘A105’ 的破洞顯著。綜合試驗結果，推測種子種皮厚薄與組織結構不同可能係造成參試2種茄子品種種子發芽性狀不一致的原因，間接影響種子的生理作用與發芽行為。然而原本 ‘A108’ 品種種子發芽表現不佳的情形，經過適當的HVEF 處理後可以有效提高種子發芽百分比、吸水率及滲漏電導度，縮短平均發芽時間，並促使種子內部可溶性蛋白質含量被提前誘導，從而改善種子的發芽表現。 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.