探討生物炭舒緩銅離子對綠豆生長的毒性

Studies on the mitigation of copper toxicity to mung bean's growth by biochar

方博政(Po-Cheng Fang)

指導教授 ： 徐邦達

國立清華大學/生命科學院/生物資訊與結構生物研究所/碩士(2016年)

摘要

自從生物炭（biochar）受到重視以來，多數的研究都著重於探討生物炭是否能增加植物產量以及生物炭本身的來源及製程；然而，對於生物炭用於去除土壤重金屬方面的研究則相對較少。因此，本論文主要探討生物炭是否能有效的吸附土壤重金屬，使植物生長恢復到一定的程度。
　　本研究主要分成兩部分，皆使用綠豆（Vigna radiata）作為研究材料，第一部分是於培養皿進行發芽測試；第二部分則進行盆栽土壤實驗。
　　培養皿發芽實驗中，我們發現生物炭能有效的吸附溶液中的銅離子，使植物生長的更好，有較高的鮮重、乾重、莖長，而且植物體內的銅含量也較低。生化檢測方面，處理生物炭的綠豆會有較高的可溶性醣類及蛋白質，以及較低的丙二醛（Malondialdehyde）含量。
　　盆栽實驗中，我們使用紅土作為材料，根據土壤汙染管制標準將盆栽分成五種不同的銅濃度，0、100、200、400、1000 mg/kg，並且於每種土壤銅濃度下分別加入0、10、20、30%（v/v）的生物炭。種植一個月後，測量鮮重、乾重、莖長、根長、各部位銅含量、可溶性醣類和蛋白質含量等。於不含銅的正常土壤中，以上各項數據差異並不大；土壤銅濃度100 mg/kg下，植物於10%生物炭含量下即可恢復正常生長狀態；200 mg/kg下則需要20%的生物炭含量；400 mg/kg時，即使30%的生物炭含量仍無法恢復正常生長狀態，但是在高生物炭含量下植物會生長的相對良好；1000 mg/kg下，20%和30%的生物炭含量下植物可以存活，但是生長不良。另一方面，銅離子會降低綠豆葉綠素含量，而生物炭可以幫助恢復葉綠素的含量但是並不是很明顯；再者，銅離子並不會影響綠豆葉綠素螢光（chlorophyll fluorescence，Fv/Fm）的數值，顯示銅離子影響植物光合作用的區域並不位在光系統II（photosystem II）。在分子層次上，我們選擇三個與活性氧（Reactive oxygen species, ROS）清除路徑相關的基因作為探討，Cu/Zn SOD、CAT、APX。發現於低銅濃度下，三個基因都會大量表現，而加入生物炭能降低基因的表現量；於高銅濃度下，則越多的生物炭能提供較好的保護，使植物有較佳的生長和表現較多的基因。

關鍵字

全球暖化 ； 綠豆 ； 生物炭 ； 銅中毒 ； 活性氧

並列摘要

Since biochar had been taken seriously, many studies are focused on whether biochar can increase the crop yield and biochar’s manufacture and process. However only few studies were about the removal of heavy metal in soil by biochar. The aim of this study is to investigate whether the biochar could absorb the heavy metal in soil and revive the plants.
We divided the study into two parts using mung beans (Vigna radiate) as material. In the first part, the seed germination in Petri dish was examined; the second part was proceeded in soil to examine the growth of plants.
In Petri dish test, we found that biochar absorb the copper ions from solution efficiently; plants grew better, exhibited higher fresh weight, dry weight, stem length and lower copper concentration. Biochemical measurement revealed that mung beans with biochar had higher soluble sugar and protein and lower malondialdehyde content.
In the soil trials, we used red soil as material, tested five different soil copper concentrations, 0, 100, 200, 400, 1000 mg/kg according to the soil pollution control standards. For each soil concentration, four different biochar contents (0, 10, 20, 30%, v/v) were applied. After growing for a month, we measured fresh weight, dry weight, stem length, root length, copper concentration of plants, the content of soluble sugar and protein. In normal soil without copper, all the above data showed no significant difference; grown under 100 mg/kg, plants in 10% biochar content grew normally; at 200 mg/kg, 20% biochar is needed for proper growth; at 400 mg/kg, even 30% biochar content couldn’t restore plants back to normal, but with high biochar content, plants grew better; at 1000 mg/kg, plants could only survive with application of 20% and 30% biochar, but not in a good condition. In addition, copper ions reduced the chlorophyll content in mung beans, but biochar partially helped with the recovery. The values of Fv/Fm showed no difference among various groups, revealing that the site of action on photosynthesis is not located in PS II. At the molecular level, three genes related with ROS scavenging were chosen for the study: Cu/Zn SOD, CAT and APX. We found that at a lower copper concentration, three genes were upregulated, and downregulated when biochar was added; at a higher copper concentration, the more biochar we added, the better the plants grew and the higher the genes expressed.

並列關鍵字

global warming ； biochar ； mung beans ； copper toxicity ； reactive oxygen species

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