小白菜經植物生長物質前處理對淹水逆境之反應

Abstract

‘三鳳’及‘鳳珍’兩品種小白菜在苗期施用根毛王0.5 mg•L-1或OHYA-5號1 mg•L-1，都可促進植株的生長及乾物重，根毛王還可促進根系的發育。當給予三天淹水逆境，對兩品種小白菜都會造成傷害，施用藥劑皆可以減緩電解質滲漏值及丙二醛的升高、維持葉綠素含量及根部TTC活性、避免植株及根系的傷害，其中以苗期施用一次，淹水前三天再施用一次根毛王效果最好，其次是淹水前三天施用一次ZnSO4或NAA，再其次是施用一次根毛王，而OHYA-5號對兩品種小白菜抗淹水能力的增加則較有限，另外鳳珍品種施用藥劑之後其抗淹水能力也較三鳳品種好，因此推論鳳珍品種可能也有對淹水逆境有較好的效果。 ‘三鳳’及‘鳳珍’兩品種小白菜，在苗期施用24-Epibrassinolide 0.01mg/L可顯著增加鳳珍品種其株高、葉福及乾物種；而三鳳品種上只有在株高達顯著差異。高於0.01mg/L濃度會使兩品種小白菜產生藥害的發生，且濃度越高藥害越嚴重。鳳珍品種在淹水三天逆境後，對照組葉綠素計讀值會有下降趨勢、離子滲漏率及丙二醛含量則會升高、超氧歧化酶（superoxide dismutase）、過氧化酶（peroxidase）、過氧化氫酶（catalase）三種抗氧化酵素也都會大幅降低、且存活率降低、抑制生長、根系死亡。而施用24-Epibrassinolide 0.01mg/L後可以使葉綠素下降趨勢減緩、有較低的離子滲漏率及丙二醛含量、三種抗氧化酵素方面，雖也有大幅降低，但是比對照組為高、且可提升存活率及根系生長。

Application of Lysine#3 0.5 mg•L-1 or OHYA-5 1 mg•L-1 at seedling stage could enhance growth and increase dry weight of Pai-Tsai（Brassica rapa L. Chinensis Group cv. ‘San-Feng’ and ‘Fun-Jen’）. Lysine#3 was could enhance root development. Two species of Pai-Tsai were harmed badly after flooding for 3 days. Application of all medicament could decrease electrolyte leakage and Malondialdehyde（MDA）content, and increase in chlorophyll content and 2,3,5-Tripheyltetrazolium chloride（TTC）activity of root, and lessen of plant harm. Applications of 0.5 mg•L-1 of Lysine#3 at seedling stage and 3 days before flooding stress were useful for increasing their resistances toward flooding stress. Applications of zinc sulphate or NAA or Lysine#3 once also could increase flooding resistance while application of OHYA-5 had limited effect on increasing stress resistances of two Pai-Tsai species. Results showed that B. rapa cv. ‘Fun-Jen’ had better flooding resistance after being applied with plant growth substances（PGSs）than B. rapa Chinensis Group cv. ‘San-Feng’ did. So we presumed that B. rapa Chinensis Group cv. ‘Fun-Jen’ could be a better flooding resistant cultivar. Application of 24-Epibrassinolide 0.01mg/L at seedling stage significantly increased plant height, plant width and dry weight of Pai-Tsai（Brassica rapa L.Chinensis Group cv. ‘Fun-Jen’）. Though only plant height of B. rapa L. Chinensis Group cv. ‘San-Feng’ was significantly enhanced by 24-Epibrassinolide. Concentration of 24-Epibrassinolide higher than 0.01mg/L caused toxicity on both species of Pai-Tsai（Brassica rapa L. Chinensis Group cv.） and the higher the concentration the worse the toxicity. After 3 days of flooding stress on Pai-Tsai（Brassica rapa Chinensis Group cv. ‘Fun-Jen’）, CMR lowered, electrolyte leakage and Malondialdehyde (MDA) content increased, activities of three anti-oxidized enzymes superoxide dismutase（SOD）, peroxidase（POX）and catalase（CATs）decreased, survival rate got down, growth inhibited, roots decayed in control treatment. Applications of 0.01mg/L of 24-Epibrassinolide at seedling stage and 1 day before flooding stress on Pai-Tsai（Brassica rapa L. Chinensis Group cv. ‘Fun-Jen’）resulted in CMR lowering less, electrolyte leakage and MDA content increased less when compared to control treatment. Activities of three anti-oxidized enzymes lowered a lot though still higher than control treatment. 24-Epibrassinolide could also increase survival rate and enhance root growth on（Brassica rapa L. Chinensis Group cv. ‘Fun-Jen’）after flooding stress.