叢枝菌根與離層酸對鹽分逆境下胡瓜幼苗生長之影響

Influence of Arbuscular Mycorrhizae and Abscisic Acid on the Growth of Cucumber (Cucumis sativus L.) Seedling under Salt Stress

‘鳳燕’胡瓜接種不同叢枝菌根菌後，調查其幼苗在鹽分逆境下之生長情形，結果顯示菌根小胡瓜比不接菌者有較佳的生長。菌種間以Glomus etunicatum Becker & Gerdemann與Glomus混合菌種（Glomus mix）的效果較Gigaspora gigantea（Nicol. & Gerd.）Gerd. & Trappe佳。鹽分逆境下胡瓜幼苗葉片中離層酸（abscisic acid, ABA）含量增加。但以菌根作物增加較為顯著。尤其是接種Glomus混合菌種者ABA增加的含量是不接菌者的16.9倍。外加ABA可顯著增加非菌根胡瓜中ABA含量。以ABA前處理後再給予鹽分逆境，比未用ABA作前處理者，可減少葉綠素、蛋白質的分解，緩和穀胺醯胺合成酵素（glutamine synthetase）活性的降低與脯胺酸的累積，維持蒸散作用的進行。顯示非菌根胡瓜幼苗中ABA含量的增加與其耐鹽性有關，但其耐鹽性仍不如菌根作物。而菌根作物外加ABA處理後，代謝物的變化不及在鹽分逆境下明顯。顯示菌根胡瓜耐鹽性可能並不全由ABA調控。

Effects of arbuscular mycorrhizae and abscisic acid on cucumber (Cucumis sativus cv. Fountain) seedling were studied. Results showed that mycorrhizal cucumber seedlings grew better than nonmycorrhizal control under salt stress. Glomus mix and Glomus etunicatum-colonized cucumber seedlings were more tolerant to salt stress than those of Gigaspora gigantea inoculation. Salt treatment resulted in an increase in abscisic acid (ABA) content, particularly to mycorrhizal cucumber seedlings. Glomus mix inoculation increased ABA content by 169% compared with control plants. Three days of ABA pretreatment could significantly increase ABA content of non-mycorrhizal cucumber seedlings. Under salt stress, ABA pretreatment could alleviate non-mycorrhizal cucumber seedlings chlorophyll and protein degradation, glutamine synthetase activity reduction, proline accumulation and water transpiration than those of non-ABA pretreatment. This suggests that the degree of salt tolerance is likely to be related to ABA in non-mycorrhizal cucumber seedlings. However, the effect of mycorrhizal cucumber seedlings on salt tolerance may not be limited to ABA. It is postulated that the significant increase of salt tolerance in mycorrhizal cucumber seedling not only existed in ABA effect but also existed in other effects.