干旱与复水对2种蟛蜞菊生长及生理生化特性的影响

Effects of drought and rewatering on growth and physiology characteristics of Wedelia chinensis and Wedelia trilobata

[目的]研究干旱及复水处理对蟛蜞菊和入侵种三裂叶蟛蜞菊生长、渗透调节物质、抗氧化酶活性等参数的影响,探讨2种蟛蜞菊对干旱环境的生态适应机制,为抑制三裂叶蟛蜞菊入侵提供理论依据。[方法]以2种蟛蜞菊扦插苗为材料,采用自然干燥法,进行15 d干旱和3 d复水试验,对照组土壤含水量为(24.4±1.23)%,比较2种蟛蜞菊干旱与复水下生长指数、叶绿素(Chl)、丙二醛(MDA)、可溶性糖、可溶性蛋白含量以及抗氧化酶(SOD、CAT、POD、APX)活性的变化。[结果](1)在干旱胁迫处理下,2种蟛蜞菊株高、单叶面积、总生物量降低,根冠比升高,且蟛蜞菊株高、单叶面积和总生物量均显著高于三裂叶蟛蜞菊,而根冠比显著低于三裂叶蟛蜞菊。复水后,2种蟛蜞菊的株高、单叶面积、总生物量均增加,而根冠比下降,且三裂叶蟛蜞菊株高、单叶面积、总生物量增加更快,根冠比下降更快,但各指标在种间均无显著差异。(2)在干旱胁迫处理下,蟛蜞菊叶绿素a、叶绿素总量和叶绿素a/b均显著增加,三裂叶蟛蜞菊则显著下降。复水后,蟛蜞菊叶绿素各指标总体降低并恢复到对照水平,三裂叶蟛蜞菊则增加(叶绿素b含量除外),且三裂叶蟛蜞菊Chla/b显著高于蟛蜞菊。(3)复水前后2种蟛蜞菊可溶性蛋白和可溶性糖含量均先升高后下降,复水后三裂叶蟛蜞菊2种渗透调节物质含量均可恢复到对照水平,但均显著低于蟛蜞菊。(4)复水前后蟛蜞菊4种抗氧化酶活性均先升高后下降,且复水后SOD、POD、CAT迅速恢复到对照水平,并抑制了MDA含量的增加。复水前后三裂叶蟛蜞SOD、POD、APX活性先升高后下降,CAT活性变化表现为先下降后升高,且复水后仅POD和APX活性恢复到对照水平。[结论]入侵种三裂叶蟛蜞菊复水后恢复能力较好,但其对干旱胁迫的耐受能力比蟛蜞菊差,在园林绿地管理中,应通过控制土壤水分含量以抑制三裂叶蟛蜞菊的生长。

[Objective] This experiment was conducted to examine effects of drought and rewatering on growth, osmotic adjustment substances and antioxidant enzymes parameters of native Wedelia chinensis and alien invasive W. trilobata to explore ecological adaptability mechanism of these two species under drought stress.This study provides basis for the inhibition of W. trilobata invasion.[Method] The cutting seedlings of these two species were selected to investigate growth index, chlorophyll content, soluble sugar, soluble protein, as well as activities of antioxidant enzymes including superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) and ascorbate peroxidase(APX) after 15 days of natural drought and 3 days of rewatering.[Result](1) Drought treatment caused decreases in plant height, single leaf area, and total biomass, and increases in root-to-shoot ratio of these two species.Plant height, single leaf area and total biomass of W. chinensis were significantly higher than those of W. trilobata,but the ratio of root to shoot of W. chinensis was significantly lower than that of W. trilobata. After rewatering, plant height, single leaf area, and total biomass increased in both species, while the ratio of root to shoot decreased.Plant height, single leaf area and total biomass of W. trilobata increased faster, and the root-to-shoot ratio of W. trilobata decreased more significantly.However, there was no significant difference between indicators of W. chinensis and W. trilobata.(2) Drought caused significant increases in chlorophyll a, total chlorophyll, and chlorophyll a/b in W. chinensis,but they decreased significantly in W. trilobata.After rewatering, chlorophyll indexes of W. chinensis decreased and recovered to normal level of the control treatment.Conversely, chlorophyll indexes increased in W. trilobata(except for chlorophyll b content),and Chla/b in W. trilobata was significantly higher than in W. trilobata.(3) Soluble protein and soluble sugar contents of both species increased under drought treatment, and decreased under rewatering. Although contents of the two osmotic adjustment contents in W. trilobata recovered to normal level after rewatering, they were significantly lower in W. trilobata than in W. chinensis.(4) Activities of antioxidant enzymes(SOD,POD,CAT and APX) of W. chinensis increased first under drought treatment, and then decreased under rewatering.SOD,CAT and POD activities quickly recovered to normal level after rewatering, which inhibited the increase of MDA content.Activities of SOD,POD and APX of W.trilobata increased first under drought treatment, while decreased under rewatering, and CAT activity had opposite trend.After rewatering, only POD and APX activities recovered to normal level.[Conclusion] The invasive W. trilobata had better recovery after rewatering, but it had worse drought tolerance than W.chinensis.It is suggested to control soil water content to inhibit W. trilobata growth in the management of green space.