李樂樂,李中陽(yáng),吳大付,班卓昊,李寶貴,樊 濤,胡 超,趙志娟,劉 源
外源物質(zhì)對(duì)鎘脅迫下不同品種冬小麥苗期鎘吸收特征的影響
李樂樂2,李中陽(yáng)1,吳大付2,班卓昊3,李寶貴1,樊 濤1,胡 超1,趙志娟1,劉 源1*
(1.中國(guó)農(nóng)業(yè)科學(xué)院 農(nóng)田灌溉研究所,河南 新鄉(xiāng) 453002;2.河南科技學(xué)院,河南 新鄉(xiāng) 453003;3.長(zhǎng)垣職業(yè)中等專業(yè)學(xué)校,河南 新鄉(xiāng) 453400)
【】分析不同外源物質(zhì)對(duì)不同品種冬小麥苗期Cd吸收和遷移特征的影響及其差異性。通過向含不同質(zhì)量濃度Cd(10、30 mg/L)的營(yíng)養(yǎng)液中添加不同質(zhì)量濃度的Si(28、56 mg/L)、Ca(50、100 mg/L)、Mg(50、100 mg/L)和腐殖酸(5、15 mg/L),在水培條件下研究了籽粒Cd高積累百農(nóng)419和低積累百農(nóng)418小麥苗期植株Cd吸收和轉(zhuǎn)運(yùn)特征、植株對(duì)Ca和Mg的吸收以及根系形態(tài)指標(biāo)的變化。不同品種冬小麥對(duì)Cd的吸收存在差異。隨著營(yíng)養(yǎng)液中Cd質(zhì)量濃度的升高,不同品種冬小麥根系生長(zhǎng)受抑制程度更嚴(yán)重。與百農(nóng)418相比,百農(nóng)419是喜Ca品種。在低Cd質(zhì)量濃度時(shí),與CK相比,低Si添加改善百農(nóng)419根系生長(zhǎng)和降低植株Cd量的效果最好,但其他物質(zhì)添加抑制了其根系生長(zhǎng)且高質(zhì)量濃度腐殖酸處理增加了根系中Cd的累積,同時(shí)所有外源物質(zhì)添加均降低了其根系Ca量;對(duì)于百農(nóng)418來說,加Si和Ca可以促進(jìn)根系生長(zhǎng)且低Si效果最明顯,加Mg和腐殖酸對(duì)根系生長(zhǎng)影響不明顯,加Si顯著降低了根系和莖葉Cd量,加Ca和Mg只顯著降低了根系Cd量,加腐殖酸對(duì)植株Cd量無(wú)顯著影響。在高Cd質(zhì)量濃度時(shí),添加Si可以促進(jìn)2種小麥根系生長(zhǎng)并降低根系和莖葉Cd量,其中低Si和高Si分別對(duì)百農(nóng)419和418根系生長(zhǎng)促進(jìn)效果更好;而其他外源物質(zhì)添加對(duì)Cd毒害基本無(wú)明顯緩解效果。與其他處理相比,低質(zhì)量濃度Cd條件下高Si顯著增加了2種小麥的Cd轉(zhuǎn)運(yùn)系數(shù),高質(zhì)量濃度Cd條件下高Si顯著增加了百農(nóng)419的Cd轉(zhuǎn)運(yùn)系數(shù)。相比其他外源物質(zhì),添加Si對(duì)冬小麥Cd毒害緩解效果最明顯,且品種、Cd質(zhì)量濃度和Si質(zhì)量濃度交互作用明顯。
小麥;硅;鎘;鈣;鎂;腐殖酸
2014年環(huán)保部和國(guó)土資源部的聯(lián)合公報(bào)表明全國(guó)土壤環(huán)境狀況總體不容樂觀,部分地區(qū)土壤污染較重,耕地土壤環(huán)境質(zhì)量堪憂,其中重金屬Cd的污染物點(diǎn)位超標(biāo)率在所有無(wú)機(jī)污染物中超標(biāo)率最高[1]?!狙芯恳饬x】當(dāng)作物組織中的Cd積累到一定程度時(shí),會(huì)使作物出現(xiàn)生長(zhǎng)遲緩、產(chǎn)量下降等癥狀,嚴(yán)重時(shí)甚至?xí)斐勺魑锼劳鯷2]。Cd還會(huì)通過食物鏈進(jìn)入人體內(nèi),對(duì)人體健康造成極大影響[3-5]。添加外源物質(zhì)可以緩解重金屬Cd對(duì)作物的毒害作用,減少Cd在作物體內(nèi)的富集[6-8]。
【研究進(jìn)展】已有研究表明不同品種冬小麥對(duì)重金屬Cd具有不同的耐受性,通過篩選重金屬Cd低積累冬小麥品種,可以有效緩解重金屬Cd污染問題[9-12]。研究發(fā)現(xiàn),Cd對(duì)苗期小麥具有嚴(yán)重的毒害作用,而添加不同的外源物質(zhì)會(huì)緩解這種毒害現(xiàn)象[13-14]。Ca是植物生長(zhǎng)必需的營(yíng)養(yǎng)元素,能夠作為第二信使與CaM(Calmodulin)結(jié)合偶聯(lián)胞外信號(hào)與胞內(nèi)生理生化反應(yīng),通過抑制Cd的吸收,促進(jìn)葉片光合作用及氣體交換速率,維持植物體的含水率、植物葉片光合色素量及礦質(zhì)營(yíng)養(yǎng)的平衡,穩(wěn)定細(xì)胞壁、細(xì)胞膜結(jié)構(gòu)及誘導(dǎo)特異性基因表達(dá)等途徑來提高植物對(duì)重金屬Cd毒害等逆境的抗性[15]。同時(shí),Ca可與Cd形成較穩(wěn)定的與土壤結(jié)合的閉蓄態(tài)Cd,從而抑制Cd進(jìn)入生物體;另一方面,Ca可與Cd競(jìng)爭(zhēng)進(jìn)入植物細(xì)胞,從而降低植物細(xì)胞Cd量[16]。Mg也是植物生長(zhǎng)必需的營(yíng)養(yǎng)元素,參與植物根的形成、葉綠素和光合作用的產(chǎn)生以及酶的活化等。Mg還可影響Cd在土壤中的賦存形態(tài)以及在植物體內(nèi)的累積和轉(zhuǎn)運(yùn),進(jìn)而緩解Cd對(duì)植物的毒害作用[17]。Si提高植物對(duì)重金屬脅迫抗性的可能機(jī)理有以下幾方面:①Si促進(jìn)根系分泌草酸,降低了Cd在植物體的積累[18];②Si與重金屬可形成沉淀,降低了重金屬的移動(dòng)性;③Si促進(jìn)Ca的吸收和轉(zhuǎn)運(yùn);④Si提高了植物抗氧化系統(tǒng)的防御能力[19]。腐殖酸可與Cd結(jié)合形成穩(wěn)定的絡(luò)合物,從而減少生物可利用態(tài)Cd,降低植物對(duì)Cd的吸收;另外,腐殖酸的添加還可改變土壤結(jié)構(gòu),進(jìn)而影響土壤中一系列生化反應(yīng),間接影響Cd的毒害作用[20-21]。Zhu等[22]和李麗君等[23]研究發(fā)現(xiàn),使用腐殖酸可以明顯降低土壤中有效態(tài)Cd量,并且提高作物的生物量,降低作物中Cd的積累?!厩腥朦c(diǎn)】添加不同的外源物質(zhì)對(duì)Cd毒害的緩解作用可能與作物的種類、品種、生長(zhǎng)條件等一系列因素有關(guān),前人研究多關(guān)注單一外源物質(zhì)或單一植物品種,而對(duì)添加不同外源物質(zhì)影響富Cd能力不同的冬小麥品種Cd吸收和遷移特征的研究較少?!緮M解決的關(guān)鍵問題】本試驗(yàn)選用前期研究發(fā)現(xiàn)的籽粒Cd積累差異明顯的2個(gè)小麥品種(籽粒Cd高積累品種百農(nóng)419和籽粒Cd低積累品種百農(nóng)418),通過水培試驗(yàn),研究不同外源物質(zhì)對(duì)不同品種冬小麥苗期Cd吸收和富集特征的影響,為重金屬Cd污染的修復(fù)和治理提供理論依據(jù)及參考。
根據(jù)前期Cd積累冬小麥品種篩選的大田試驗(yàn)結(jié)果選用了2種小麥(百農(nóng)419和百農(nóng)418)進(jìn)行試驗(yàn)。選擇籽粒飽滿的小麥種子在75%酒精中浸泡5 min殺菌,再用蒸餾水洗掉殘余的酒精,溫水浸泡1 h后,將種子均勻擺放在帶網(wǎng)格的育苗盤中催芽。待小麥長(zhǎng)到二葉一心期時(shí),將其移栽到配制好的改良霍格蘭營(yíng)養(yǎng)液(購(gòu)自山東拓普生物工程有限公司)中[24],成分見表1。每8株小麥放置在1個(gè)盛1 L營(yíng)養(yǎng)液的灰色PVC小桶(直徑10 cm,高20 cm)中。營(yíng)養(yǎng)液用400 g/L NaOH溶液調(diào)節(jié)pH值至6.0,小麥在營(yíng)養(yǎng)液培養(yǎng)2 d后開始試驗(yàn)。鑒于目前我國(guó)土壤Cd污染的嚴(yán)峻形勢(shì)[25-28],本試驗(yàn)營(yíng)養(yǎng)液中Cd(CdCl2)質(zhì)量濃度設(shè)置了2個(gè)水平(10、30 mg/L),縮寫為Cd10和Cd30。通過化學(xué)平衡模擬軟件Visual MINTEQ計(jì)算pH值6.0營(yíng)養(yǎng)液中Cd的形態(tài)及質(zhì)量濃度結(jié)果表明2種質(zhì)量濃度下加入的Cd約99.999%存在于溶液中,基本無(wú)沉淀。在不同水平的含Cd營(yíng)養(yǎng)液中添加不同的外源物質(zhì),每種外源物質(zhì)設(shè)置2個(gè)水平。外源物質(zhì)Si(Na2SiO3·9H2O)的質(zhì)量濃度設(shè)置為28 mg/L(S1)、56 mg/L(S2),Ca(CaCl2)的質(zhì)量濃度設(shè)置為50 mg/L(C1)、100 mg/L(C2),Mg(MgCl2)的質(zhì)量濃度設(shè)置為50 mg/L(M1)、100 mg/L(M2),腐殖酸(90%黃腐酸)質(zhì)量濃度設(shè)置為5 mg/L(F1)、15 mg/L(F2)。同時(shí)在2種Cd質(zhì)量濃度下設(shè)置只添加Cd不添加外源物質(zhì)的對(duì)照(CK),另外還設(shè)置了不加Cd不加外源物質(zhì)的正常營(yíng)養(yǎng)液CK(Cd0)。共38個(gè)處理,每個(gè)處理4次重復(fù),總計(jì)152個(gè)小桶。水培試驗(yàn)在人工氣候室中進(jìn)行,溫度25 ℃,光照時(shí)間為08:00—18:00。每3天更換1次營(yíng)養(yǎng)液,處理30 d后收樣。
表1 改良霍格蘭營(yíng)養(yǎng)液成分
試驗(yàn)處理30 d后將樣品從營(yíng)養(yǎng)液中取出,用蒸餾水沖洗后分成根和莖葉[29]。莖葉先在烘箱中105 ℃殺青0.5 h,然后在70 ℃下烘干至恒質(zhì)量。每個(gè)處理隨機(jī)挑選3株小麥根系,用WinRHI-ZO 系列植物根系掃描儀進(jìn)行掃描,得出3株小麥根系總長(zhǎng)度、根系總表面積、根系總體積和根尖數(shù)之和。然后所有根系烘干,烘干后的樣品用粉碎機(jī)(Taisite FW100)磨碎并充分混合均勻裝袋。消煮時(shí)稱取0.200 g植物樣加入10 mL濃HNO3,用微波消解儀(Mars CEM 240/50)進(jìn)行消解,同時(shí)做4個(gè)空白。消煮液趕酸定容后用原子吸收分光光度計(jì)(火焰+石墨爐)(PinAAcle 900,PerkinElmer,美國(guó))測(cè)定Cd量。轉(zhuǎn)運(yùn)系數(shù)=莖葉含Cd量/根系含Cd量。
采用Excel 2007對(duì)數(shù)據(jù)進(jìn)行整理和作圖,采用SAS 9.2軟件進(jìn)行單因素方差分析(One-way ANOVA),并對(duì)不同處理間的差異進(jìn)行Duncan多重比較,顯著性水平為=0.05。采用SPSS 16.0進(jìn)行三因素方差分析。
小麥根系形態(tài)指標(biāo)結(jié)果如表2和表3所示,所有指標(biāo)均為3株小麥一起掃描的結(jié)果。在不加Cd不加外源物質(zhì)的正常營(yíng)養(yǎng)液中(表2),2種小麥品種的根系生長(zhǎng)無(wú)顯著性差異。添加不同的外源物質(zhì)對(duì)小麥根系形態(tài)指標(biāo)的影響如表3所示。由表3可知,與正常營(yíng)養(yǎng)液中根系各形態(tài)指標(biāo)相比,添加2種質(zhì)量濃度的Cd顯著抑制了2種小麥根系生長(zhǎng)。在只添加低質(zhì)量濃度Cd的營(yíng)養(yǎng)液中,百農(nóng)419的根系生長(zhǎng)顯著優(yōu)于百農(nóng)418;但Cd高質(zhì)量濃度時(shí)二者無(wú)顯著差異。
在Cd質(zhì)量濃度為10 mg/L時(shí),與CK相比,加Si增加了百農(nóng)419總根長(zhǎng)、總根表面積、總根體積和總根尖數(shù),且在低質(zhì)量濃度Si處理達(dá)顯著水平,增幅分別為92.17%、102.75%、113.73%、71.08%;在加Ca、Mg、腐殖酸條件下百農(nóng)419各根系形態(tài)指標(biāo)均顯著下降,加高質(zhì)量濃度腐殖酸時(shí)降幅最大,分別為75.81%、68.46%、58.80%、70.16%。添加外源物質(zhì)后百農(nóng)418各根系形態(tài)指標(biāo)相比CK均上升,加Mg和腐殖酸處理增加不顯著,加Si和Ca處理達(dá)到顯著水平,Si的效果顯著優(yōu)于Ca,且低質(zhì)量濃度Si增加效果顯著優(yōu)于高質(zhì)量濃度,低質(zhì)量濃度Si時(shí)總根長(zhǎng)、總根表面積、總根體積和總根尖數(shù)分別增加了292.94%、304.92%、320.75%、312.19%。
表2 正常營(yíng)養(yǎng)液中不同小麥品種根系形態(tài)指標(biāo)
注 表中同列不同小寫字母代表處理間差異顯著(0.05)。
表3 添加不同外源物質(zhì)或Cd時(shí)不同小麥品種根系形態(tài)指標(biāo)
注 表中同列不同小寫字母代表處理間差異顯著(0.05)。
當(dāng)Cd質(zhì)量濃度為30 mg/L時(shí),百農(nóng)419低Si處理各根系形態(tài)指標(biāo)顯著優(yōu)于不添加外源物質(zhì)的CK處理,增幅分別為118.75%、133.68%、148.65%、83.76%;高質(zhì)量濃度Si相比CK只顯著增加了總根長(zhǎng);添加腐殖酸、Ca、Mg的影響不顯著,低質(zhì)量濃度腐殖酸對(duì)根系生長(zhǎng)最不利,總根長(zhǎng)、總根表面積、總根體積和總根尖數(shù)相比CK下降幅度分別為2.21%、6.93%、10.81%、18.66%。與CK相比,只有高質(zhì)量濃度Si的添加顯著改善了百農(nóng)418根系各形態(tài)指標(biāo),高Si時(shí)總根長(zhǎng)、總根表面積、總根體積和總根尖數(shù)增幅分別為93.80%、159.70%、252.94%、42.37%。說明添加外源物質(zhì)Si可以有效緩解根系Cd毒害現(xiàn)象,低質(zhì)量濃度Si對(duì)百農(nóng)419兩種質(zhì)量濃度Cd毒害以及百農(nóng)418低質(zhì)量濃度Cd毒害的緩解效果較好,高質(zhì)量濃度Si對(duì)百農(nóng)418高質(zhì)量濃度Cd毒害的緩解效果較好。
品種、Cd質(zhì)量濃度和相同外源物質(zhì)3個(gè)質(zhì)量濃度的三因素方差分析結(jié)果如表4所示。從表4可以看出添加Si條件下,不同處理間根系總根長(zhǎng)和總根表面積的差異主要是由Cd質(zhì)量濃度和外源物質(zhì)量濃度造成的。添加腐殖酸條件下,品種、Cd質(zhì)量濃度和腐殖酸質(zhì)量濃度共同造成了根系形態(tài)指標(biāo)的差異。添加Ca條件下,差異主要是由Cd質(zhì)量濃度造成的。添加Mg條件下,差異主要是由品種和Cd質(zhì)量濃度造成的。
表4 根系形態(tài)指標(biāo)的三因素方差分析
注 加粗的數(shù)值代表有顯著差異,其中<0.05代表差異顯著,<0.01代表差異極顯著。
不同處理?xiàng)l件下小麥根系Ca和Mg量圖1(a)—圖1(d)所示。在正常營(yíng)養(yǎng)液中生長(zhǎng)的百農(nóng)419和百農(nóng)418根系Ca量分別為610 mg/kg和360 mg/kg,根系Mg量分別為999 mg/kg和583 mg/kg,百農(nóng)419根系的Ca和Mg量明顯高于百農(nóng)418,說明百農(nóng)419相比于百農(nóng)418更喜Ca和Mg。在低Cd條件下,與CK相比,添加外源物質(zhì)均降低了百農(nóng)419根系Ca量,對(duì)百農(nóng)419和百農(nóng)418根系Mg量基本無(wú)影響(除了高Si處理),卻增加了百農(nóng)418根系Ca量(除個(gè)別例外)。高Cd條件下,與CK相比,2種質(zhì)量濃度Si處理均降低了百農(nóng)419根系Ca和Mg量,而增加了百農(nóng)418根系Ca量;而所有外源物質(zhì)添加對(duì)百農(nóng)418根系Mg量無(wú)顯著影響。
不同處理?xiàng)l件下小麥莖葉Ca和Mg量圖1(e)—圖1(h)所示。在正常營(yíng)養(yǎng)液中生長(zhǎng)的百農(nóng)419和百農(nóng)418莖葉的Ca量分別為1 082 mg/kg和838 mg/kg,莖葉Mg量分別為3 214 mg/kg和2 931 mg/kg。與CK相比,2種Cd質(zhì)量濃度下不同外源物質(zhì)添加對(duì)百農(nóng)419莖葉Ca和Mg量基本無(wú)顯著影響,除了高Cd條件下高Si處理顯著增加了百農(nóng)419莖葉Ca量。2種Cd質(zhì)量濃度下,添加外源物質(zhì)的百農(nóng)418莖葉Mg量與CK無(wú)顯著差異。在低Cd條件下,高Si和低Ca處理的百農(nóng)418莖葉Ca量顯著高于CK;高Cd條件下,低Ca和高Ca處理的百農(nóng)418莖葉Ca量顯著高于CK。
添加不同外源物質(zhì)對(duì)小麥根系和莖葉Cd量的影響如圖2所示。當(dāng)營(yíng)養(yǎng)液中不添加外源物質(zhì)與Cd時(shí),百農(nóng)419和百農(nóng)418根系和莖葉中均未檢測(cè)到Cd。添加不同的外源物質(zhì)對(duì)2種小麥根系和莖葉Cd量影響不同。隨著Cd質(zhì)量濃度的升高,2種冬小麥根系和莖葉Cd量均上升。從圖2(a)可以看出,在Cd質(zhì)量濃度為10 mg/L時(shí),與CK相比,外源Si顯著抑制了百農(nóng)419根系對(duì)Cd的吸收,高Si降幅最大為85.62%;加Ca、Mg的根系Cd量與CK無(wú)顯著差異;加腐殖酸反而促進(jìn)了根系對(duì)Cd的吸收,高腐殖酸時(shí)根系Cd量相比CK增加最多(43.48%),加重了Cd毒害作用,與根系形態(tài)結(jié)果一致。在Cd質(zhì)量濃度為30 mg/L時(shí),添加2種質(zhì)量濃度的Si以及高質(zhì)量濃度Mg顯著抑制了百農(nóng)419根系對(duì)Cd的吸收,高Si抑制作用最強(qiáng),相比CK降低了79.17%;其余處理對(duì)根系Cd量無(wú)顯著影響。這與根系形態(tài)結(jié)果不一致,說明高Si雖然沒有明顯改善百農(nóng)419的根系形態(tài),卻顯著降低了根系吸收的Cd。
圖2 添加不同外源物質(zhì)時(shí)小麥根系和莖葉Cd量
不同外源物質(zhì)對(duì)百農(nóng)418根系Cd量影響的結(jié)果如圖2(b)所示。在Cd質(zhì)量濃度為10 mg/L時(shí),除腐殖酸外,其他處理相比CK均顯著降低了百農(nóng)418根系Cd量,高Si的降幅最大為87.59%。在Cd質(zhì)量濃度為30 mg/L時(shí),添加2種質(zhì)量濃度Si相比CK顯著降低了百農(nóng)418根系Cd量,高Si降幅最大為64.24%;另外高Ca處理顯著降低了根系Cd量、高M(jìn)g處理顯著增加了根系Cd量。從圖2(c)可以看出,在Cd質(zhì)量濃度為10 mg/L時(shí),相比CK加Si顯著降低了百農(nóng)419莖葉Cd量,但2種Si質(zhì)量濃度無(wú)顯著差異,其他處理影響不顯著;Cd質(zhì)量濃度為30 mg/L時(shí)不同處理與CK的差異與低質(zhì)量濃度Cd類似,但低Si對(duì)百農(nóng)419莖葉含Cd量的降低作用(76.87%)顯著大于高Si。不同外源物質(zhì)對(duì)低質(zhì)量濃度Cd條件下百農(nóng)418莖葉Cd量的影響與百農(nóng)419相似(圖2(d)),相比CK低Si處理對(duì)莖葉Cd量降低作用(68.07%)最明顯。在Cd質(zhì)量濃度為30 mg/L時(shí),相比CK加Ca顯著增加了百農(nóng)418莖葉Cd量,最大增幅為36.32%(C1);加Si處理顯著降低了莖葉含Cd量,最大降幅為88.18%(S2);其余處理?xiàng)l件下無(wú)顯著影響。
植株Cd量的三因素方差分析結(jié)果如表5所示。由表5可知,添加Si條件下,根系Cd量差異主要是Cd質(zhì)量濃度和Si質(zhì)量濃度造成的,莖葉Cd量差異主要是由品種、Cd質(zhì)量濃度和Si質(zhì)量濃度造成的。添加腐殖酸條件下,根系Cd量差異主要由是品種和Cd質(zhì)量濃度引起的,而莖葉Cd量差異主要是由Cd質(zhì)量濃度引起的。添加Ca條件下,根系Cd量差異主要是由品種、Cd質(zhì)量濃度和Ca質(zhì)量濃度導(dǎo)致的,莖葉Cd量差異主要是由品種和Cd質(zhì)量濃度導(dǎo)致的。添加Mg條件下Cd質(zhì)量濃度是造成植株Cd量差異的主要因素。
表5 植株Cd量和Cd轉(zhuǎn)運(yùn)系數(shù)的三因素方差分析
注 加粗的數(shù)值代表有顯著差異,其中<0.05代表差異顯著,<0.01代表差異極顯著。
由圖3可知,在Cd質(zhì)量濃度為10 mg/L時(shí),百農(nóng)419的轉(zhuǎn)運(yùn)系數(shù)普遍高于百農(nóng)418,高Si處理?xiàng)l件下百農(nóng)419和百農(nóng)418轉(zhuǎn)運(yùn)系數(shù)>1,顯著高于其他處理?xiàng)l件下百農(nóng)419和百農(nóng)418轉(zhuǎn)運(yùn)系數(shù)。在Cd質(zhì)量濃度為30 mg/L時(shí),只有高Si處理百農(nóng)419轉(zhuǎn)運(yùn)系數(shù)>1,顯著高于其他處理?xiàng)l件下百農(nóng)419轉(zhuǎn)運(yùn)系數(shù),百農(nóng)418在所有處理?xiàng)l件下轉(zhuǎn)運(yùn)系數(shù)均<1。
植株Cd轉(zhuǎn)運(yùn)系數(shù)的三因素方差分析結(jié)果如表5所示。由表5可知,添加Si條件下,轉(zhuǎn)運(yùn)系數(shù)差異主要是由品種、Cd質(zhì)量濃度和Si質(zhì)量濃度造成的。添加腐殖酸條件下,轉(zhuǎn)運(yùn)系數(shù)差異主要是Cd質(zhì)量濃度引起的。添加Ca條件下,轉(zhuǎn)運(yùn)系數(shù)差異主要是源于Cd質(zhì)量濃度和Ca質(zhì)量濃度差異。
圖3 添加不同外源物質(zhì)時(shí)不同品種冬小麥Cd轉(zhuǎn)運(yùn)系數(shù)
根系形態(tài)指標(biāo)是評(píng)價(jià)作物對(duì)Cd耐性的重要指標(biāo)。當(dāng)作物生長(zhǎng)環(huán)境中Cd質(zhì)量濃度過高會(huì)導(dǎo)致作物生長(zhǎng)緩慢并矮化,而添加不同外源物質(zhì)可以緩解這一現(xiàn)象。本研究中2種小麥都是敏感品種,表現(xiàn)為在Cd處理?xiàng)l件下根系生長(zhǎng)都受到了明顯的抑制,且隨著Cd質(zhì)量濃度的升高,抑制作用更明顯,根系以及莖葉含Cd量明顯上升。在低Cd質(zhì)量濃度時(shí),與CK相比,百農(nóng)418在各處理?xiàng)l件下各根系形態(tài)指標(biāo)均改善,改善效果表現(xiàn)為:Si>Ca>Mg>腐殖酸;而百農(nóng)419只在Si處理?xiàng)l件下各根系形態(tài)指標(biāo)優(yōu)于CK。在高Cd質(zhì)量濃度時(shí),不同外源物質(zhì)對(duì)2種小麥品種的影響也不同。造成這種差異的原因主要是種內(nèi)差異[30]。二者對(duì)Cd毒害的解毒機(jī)制差異可能是導(dǎo)致這種差異的原因之一。吸收到植物體內(nèi)的Cd會(huì)啟動(dòng)植物的自我保護(hù)系統(tǒng)以降低Cd在植株體內(nèi)的轉(zhuǎn)運(yùn)和累積,而這種自我保護(hù)系統(tǒng)在不同植物或品種的差異會(huì)造成植物的不同器官和不同品種間Cd的積累量不同[31]。在本研究中體現(xiàn)為低Cd無(wú)外源物質(zhì)的CK下,百農(nóng)418根系Cd量明顯高于百農(nóng)419,而百農(nóng)419的轉(zhuǎn)運(yùn)系數(shù)高于百農(nóng)418。另一個(gè)可能的原因是二者對(duì)Ca的需求量不同。百農(nóng)419需Ca量較多,但所有外源物質(zhì)添加均導(dǎo)致了根系Ca量減少,其中腐殖酸處理還導(dǎo)致根系累積Cd增加,而百農(nóng)418根系在添加外源物質(zhì)后Ca量未下降且Cd量下降,因此百農(nóng)419的根系生長(zhǎng)相對(duì)于CK受抑制作用明顯,百農(nóng)418的根系未受到明顯影響。另外,不同植物或品種根系陽(yáng)離子交換量、Zeta電位等帶電性質(zhì)的差異會(huì)影響根系對(duì)Cd的吸附和吸收[32],環(huán)境條件的改變也會(huì)導(dǎo)致植物不同品種對(duì)Cd的耐受能力的差異[8]。因此,依據(jù)小麥不同品種Cd吸收的差異特性[10-11,33]可以在篩選重金屬低積累小麥品種的基礎(chǔ)上施用合適的外源物質(zhì)并配合適當(dāng)?shù)脑耘啻胧┙档托←溨亟饘俪瑯?biāo)的風(fēng)險(xiǎn)[34]。
本研究比較了4種外源物質(zhì)對(duì)Cd毒害的緩解效果,但4種物質(zhì)的效果在2種小麥品種表現(xiàn)不盡相同。不同外源物質(zhì)中Si對(duì)不同品種冬小麥根系和莖葉Cd量降低效果最好,但添加Ca、Mg和腐殖酸并不總是緩解Cd毒害。研究表明,水稻幼苗在Ca質(zhì)量濃度較低時(shí),Cd在根部和莖葉的量高于Cd單獨(dú)處理時(shí)[35],說明Ca在一定質(zhì)量濃度會(huì)促進(jìn)作物對(duì)Cd的吸收,加重Cd的毒害。熊禮明等[36]研究也證明了上述結(jié)果。朱華蘭[37]研究表明,缺Mg和Mg過量均不能緩解玉米對(duì)Cd的吸收,即Mg對(duì)Cd毒害的緩解作用取決于添加Mg的質(zhì)量濃度。孫梟瓊等[38]研究表明,腐殖酸鈉對(duì)冬小麥種子Cd毒害的緩解作用也依賴于添加的質(zhì)量濃度。這也部分解釋了本研究在一定Cd質(zhì)量濃度脅迫下添加Ca、Mg和腐殖酸反而降低了各根系形態(tài)指標(biāo)。
轉(zhuǎn)運(yùn)系數(shù)體現(xiàn)出植物地上部轉(zhuǎn)運(yùn)根部重金屬的能力,系數(shù)的高低將直接影響植物抵御重金屬毒害的能力。由圖3可知,在CK、F1、F2、S1、C1、C2、M1和M2處理下2種小麥轉(zhuǎn)運(yùn)系數(shù)均<1,說明Cd主要積累在根系中,這與前人研究結(jié)果[12]相同。而在高質(zhì)量濃度Si處理下不同品種冬小麥轉(zhuǎn)運(yùn)系數(shù)>1,說明加入高質(zhì)量濃度Si抑制了根系對(duì)Cd的吸收,卻提升了Cd向莖葉轉(zhuǎn)運(yùn)的能力。也有研究表明加Si可降低Cd轉(zhuǎn)運(yùn)系數(shù)[39],與本研究結(jié)論不一致,可能是由于本試驗(yàn)Si添加量較高,而且本研究也證實(shí)2種Si添加量下Cd轉(zhuǎn)運(yùn)系數(shù)有顯著差異。Si并不總是降低Cd轉(zhuǎn)運(yùn)系數(shù)。有研究表明加Si后Cd在水稻各部位的轉(zhuǎn)運(yùn)系數(shù)因土壤pH而異[40]。另一個(gè)關(guān)于大蒜的研究中也發(fā)現(xiàn)加Si提高了Cd的轉(zhuǎn)移系數(shù)[41]。另外,加Si對(duì)重金屬轉(zhuǎn)運(yùn)系數(shù)的影響隨著生育期的推進(jìn)而改變[42]。說明Si對(duì)Cd在植物體內(nèi)轉(zhuǎn)運(yùn)的影響還有待進(jìn)一步研究。另外,低Cd時(shí)百農(nóng)419表現(xiàn)出較強(qiáng)的Cd轉(zhuǎn)運(yùn)能力,這與前期大田試驗(yàn)結(jié)果[43]一致,說明在Cd污染土壤中種植百農(nóng)419有較高風(fēng)險(xiǎn),可能會(huì)導(dǎo)致地上部分和籽粒積累較高的Cd。
百農(nóng)419和百農(nóng)418均為Cd敏感小麥品種,百農(nóng)419比百農(nóng)418對(duì)Ca的需求更高。
在Cd質(zhì)量濃度為10 mg/L時(shí),對(duì)于百農(nóng)419來說,加Si緩解了Cd毒害,但加其他物質(zhì)無(wú)緩解作用;對(duì)于百農(nóng)418來說,加Si同樣緩解了Cd毒害,加Ca促進(jìn)了根系生長(zhǎng)且降低了根系Cd量,加Mg只降低了根系Cd量,加腐殖酸無(wú)明顯作用。
在Cd質(zhì)量濃度為30 mg/L時(shí),加Si促進(jìn)了2種小麥根系生長(zhǎng)并降低了植株Cd量,其中低Si和高Si分別對(duì)百農(nóng)419和百農(nóng)418根系生長(zhǎng)促進(jìn)效果更好;而其他物質(zhì)添加對(duì)Cd毒害基本無(wú)明顯緩解效果。
高Si顯著增加了低Cd條件下2種小麥品種的Cd轉(zhuǎn)運(yùn)系數(shù)以及高Cd條件下百農(nóng)419的Cd轉(zhuǎn)運(yùn)系數(shù)。
因此,不同外源物質(zhì)對(duì)2種小麥品種Cd毒害緩解效果最好的為Si,且存在品種、Cd質(zhì)量濃度和Si質(zhì)量濃度的明顯交互作用。
[1] 環(huán)境保護(hù)部和國(guó)土資源部發(fā)布全國(guó)土壤污染狀況調(diào)查公報(bào)[J]. 資源與人居環(huán)境, 2014 (4): 26-27.
Ministry of Environmental Protection and Ministry of Land and Resources release national survey bulletin on soil pollution[J]. Resources Environment Inhabitant. 2014 (4): 26-27.
[2] 薛永, 王苑螈, 姚泉洪, 等. 植物對(duì)土壤重金屬鎘抗性的研究進(jìn)展[J]. 生態(tài)環(huán)境學(xué)報(bào), 2014, 23(3): 528-534.
XUE Yong, WANG Yuanyuan, YAO Quanhong, et al. Research progress of plants resistance to heavy metal Cd in soil[J]. Ecology and Environment Sciences, 2014, 23(3): 528-534.
[3] 王科, 李浩, 張成, 等. 不同類型土壤下水稻鎘的富集特征及與土壤鎘量的關(guān)系[J]. 四川農(nóng)業(yè)科技, 2018 (11): 38-40.
WANG Ke, LI Hao, ZHANG Cheng, et al. Accumulation of cadmium in rice in different types of soil and its relationship with soil cadmium content[J]. Sichuan Agricultural Science and Technology, 2018(11): 38-40.
[4] 駱翠紅. 淺談土壤鎘污染的修復(fù)技術(shù)[J]. 中國(guó)資源綜合利用, 2018, 36(2): 73-75.
LUO Cuihong. Discussion on remediation technology of soil cadmium pollution[J]. China Resources Comprehensive Utilization, 2018, 36(2): 73-75.
[5] 張偉杰, 徐建新. 三峽庫(kù)區(qū)干流沉積物重金屬質(zhì)量分?jǐn)?shù)及污染評(píng)價(jià)[J]. 灌溉排水學(xué)報(bào), 2018, 37(5): 99-105.
ZHANG Weijie, XU Jianxin. Assessing contents and pollution of heavy metals within the sediment deposits in the main streams of the Three Gorges Reservoir[J]. Journal of Irrigation and Drainage, 2018, 37(5): 99-105.
[6] MARYAM Haghighi, M. Kafi, P. Fang, et al. Humic acid decreased hazardous of cadmium toxicity on lettuce (Lactuca sativa L.)[J]. Vegetable Crops Research Bulletin, 2010, 72, 49-61.
[7] HUANG Fei, WEN Xiaohui, CAI Yixia, et al. Silicon-mediated enhancement of heavy metal tolerance in rice at different growth stages[J]. International Journal of Environmental Research and Public Health, 2018, 15(10): 2193.
[8] KANU Adam Sheka, ASHRAF Umair, MO Zhaowen, et al. Calcium amendment improved the performance of fragrant rice and reduced metal uptake under cadmium toxicity[J]. Environmental Science and Pollution Research, 2019, 26(24): 24 748-24 757.
[9] 張玉燭, 方寶華, 滕振寧, 等. 應(yīng)急性鎘低積累水稻品種篩選與驗(yàn)證[J]. 湖南農(nóng)業(yè)科學(xué), 2017 (12): 19-25.
ZHANG Yuzhu, FANG Baohua, TENG Zhenning, et al. Screening and verification of rice varities with low cadmium accumulation[J]. Hunan Agricultural Sciences, 2017(12): 19-25.
[10] 肖亞濤, 吳海卿, 李中陽(yáng), 等. 不同基因型冬小麥鎘累積差異及其與根系形態(tài)的關(guān)系[J]. 水土保持學(xué)報(bào), 2015, 29(6): 276-280.
XIAO Yatao, WU Haiqing, LI Zhongyang, et al. Difference of cadmium accumulation by different genotypes of winter wheat and its relationship with root morphology[J]. Journal of Soil and Water Conservation, 2015, 29(6): 276-280.
[11] 林小兵, 周利軍, 王惠明, 等. 不同水稻品種對(duì)重金屬的積累特性[J]. 環(huán)境科學(xué), 2018, 39(11): 5 198-5 206.
LIN Xiaobing, ZHOU Lijun, WANG Huiming, et al. Accumulation of heavy metals in different rice varieties[J]. Environmental Science, 2018, 39(11): 5 198-5 206.
[12] 鄧洪, 劉惠見, 牛婧, 等. 玉米重金屬低累積品種的篩選與研究[C]// 中國(guó)土壤學(xué)會(huì)土壤環(huán)境專業(yè)委員會(huì)第二十次會(huì)議暨農(nóng)田土壤污染與修復(fù)研討會(huì)摘要集, 合肥, 2018: 34.
DENG Hong, LIU Huijian, NIU Jing, et al. Screening and Study of Maize Heavy Metal Low Accumulation Varieties[C]// The 20th Meeting of Soil Environment Professional Committee of Chinese Soil Society and Symposium on Farmland Soil Pollution and Remediation. Hefei, 2018: 34.
[13] 周相玉, 馮文強(qiáng), 秦魚生, 等. 鎂、錳、活性炭和石灰及其交互作用對(duì)小麥鎘吸收的影響[J]. 生態(tài)學(xué)報(bào), 2013, 33(14): 4 289-4 296.
ZHOU Xiangyu, FENG Wenqiang, QIN Yusheng, et al. Effects of magnesium, manganese, activated carbon and lime and their interactions on cadmium uptake by wheat[J]. Acta Ecologica Sinica, 2013, 33(14): 4 289-4 296.
[14] 師振亞. 硅對(duì)小麥幼苗鎘毒害的緩解作用研究[D]. 鄭州: 河南農(nóng)業(yè)大學(xué), 2018.
SHI Zhenya. Allevition of exogenous silion on cadmium toxicity in wheat seedlings[D]. Zhengzhou: Henan Agricultural University, 2018.
[15] 王巧玲, 鄒金華, 劉東華, 等. 外源鈣(Ca)對(duì)毛蔥耐鎘(Cd)脅迫能力的影響[J]. 生態(tài)學(xué)報(bào), 2014, 34(5): 1 165-1 177.
WANG Qiaoling, ZOU Jinhua, LIU Donghua, et al. Effects of exogenous calcium (Ca) on tolerance of Allium cepa var. agrogarum L. to cadmium (Cd) stress[J]. Acta Ecologica Sinica, 2014, 34(5): 1 165-1 177.
[16] 杜文琪. 外源鎂對(duì)鎘在稻田系統(tǒng)中生物有效性與轉(zhuǎn)運(yùn)累積的影響[D]. 長(zhǎng)沙: 中南林業(yè)科技大學(xué), 2018.
DU Wenqi. Effects of exogenous magnesium on bioavailability, transportation and accumulation of cadmium in rice-soil system[D]. Changsha: Central South University of Forestry and Technology, 2018.
[17] KASHEM Md Abul, KAWAI Shigenao. Alleviation of cadmium phytotoxicity by magnesium in Japanese mustard spinach[J]. Soil Science and Plant Nutrition, 2007, 53(3): 246-251.
[18] WU Jiawen, CHRISTOPH-MARTIN Geilfus, BRITTA Pitann, et al. Silicon-enhanced oxalate exudation contributes to alleviation of cadmium toxicity in wheat[J]. Environmental and Experimental Botany, 2016, 131: 10-18.
[19] 宋阿琳. 小白菜對(duì)鎘脅迫的響應(yīng)及硅緩解鎘毒害的機(jī)制[D]. 南京: 南京農(nóng)業(yè)大學(xué), 2009.
SONG Alin, Responses of Brassica chinensis L. to cadmium stress and silicon-alleviated cadmium toxicity[D]. Nanjing: Nanjing Agricultural University, 2009.
[20] NAGASAWA Kenya, WANG Binhui, NISHIYA Kazuki, et al. Effects of humic acids derived from lignite and cattle manure on antioxidant enzymatic activities of barley root[J]. Journal of Environmental Science and Health, Part B, 2016, 51(2): 81-89.
[21] KHAN Kiran Yasmin, ALI Barkat, CUI Xiaoqiang, et al. Effect of humic acid amendment on cadmium bioavailability and accumulation by pak choi (Brassica rapa ssp chinensis L.) to alleviate dietary toxicity risk[J]. Archives of Agronomy and Soil Science, 2017, 63(10): 1 431-1 442.
[22] ZHU Hanhua, CHEN Cheng, XU Chao, et al. Effects of soil acidification and liming on the phytoavailability of cadmium in paddy soils of central subtropical China[J]. Environmental Pollution, 2016, 219: 99-106.
[23] 李麗君, 張強(qiáng), 白光潔, 等. 改良劑與油菜對(duì)土壤重金屬有效態(tài)的影響[J]. 水土保持學(xué)報(bào), 2014, 28(1): 246-252.
LI Lijun, ZHANG Qiang, Bai Guangjie, et al. The Influence of amendments and rape on available heavy metals content in soil[J]. Journal of Soil and Water Conservation, 2014, 28(1): 246-252.
[24] 賈瑞星, 丁鑫超, 湯丹峰, 等. 鎘對(duì)兩個(gè)同核異質(zhì)紅麻雜交種種子萌發(fā)及幼苗生長(zhǎng)的影響[J]. 南方農(nóng)業(yè)學(xué)報(bào), 2019, 50(8): 1 688-1 694.
JIA Ruixing, DING Xinchao, TANG Danfeng, et al. Effects of seed germination and seedling growth of two homonuclear- heterocytoplasmic kenaf hybrid cultivars under cadmium stress[J]. Journal of Southern Agriculture, 2019, 50(8): 1 688-1 694.
[25] 李艷玲, 盧一富, 陳衛(wèi)平, 等. 工業(yè)城市農(nóng)田土壤重金屬時(shí)空變異及來源解析[J]. 環(huán)境科學(xué), 2020, 41(3): 1 432-1 439.
LI Yanling, LU Yifu, CHEN Weiping, et al. Spatial-temporal variation and source change of heavy metals in the cropland soil in industrial city[J]. Environmental Science, 2020, 41(3): 1 432-1 439.
[26] 王敏, 蔣澤海. 環(huán)境衛(wèi)生監(jiān)測(cè)項(xiàng)目土壤中鎘的檢測(cè)結(jié)果分析[J]. 世界有色金屬, 2019, 19: 283-284.
WANG Min, JIANG Zehai. Analysis on the detection results of cadmium in soil of 2018 rural environmental health monitoring project in Liupanshui City[J]. World Nonferrous Metal, 2019, 19: 283-284.
[27] 陳兆進(jìn), 李英軍, 邵洋, 等. 新鄉(xiāng)市鎘污染土壤細(xì)菌群落組成及其對(duì)鎘固定效果[J]. 環(huán)境科學(xué), 2020, 41(6): 2 889-2 897.
CHEN Zhaojin, LI Yingjun, SHAO Yang, et al. Bacterial Community composition in cadmium-contaminated soils in Xinxiang city and its ability to reduce cadmium bioaccumulation in Pak Choi (Brassica chinensis L.)[J]. Environmental Science, 2020, 41(6): 2 889-2 897.
[28] 夏雪姣, 菅明陽(yáng), 韓玉翠, 等. 鎘脅迫對(duì)小麥形態(tài)發(fā)育及生理代謝的影響[J]. 農(nóng)業(yè)生物技術(shù)學(xué)報(bào), 2018, 26(9): 1 494-1 503.
XIA Xuejiao, JIAN Mingyang, HAN Yucui, et al. Effects of cadmium stress on morphological development and physiological metabolism in wheat (Triticum aestivum)[J]. Chinese Journal of Agricultural Biotechnology, 2018, 26(9): 1 494-1 503.
[29] KIKUCHI Tetsuro, OKAZAKI Masanori, MOTOBAYASHI Takashi. Suppressive effect of magnesium oxide materials on cadmium accumulation in winter wheat grain cultivated in a cadmium- contaminated paddy field under annual rice–wheat rotational cultivation[J]. Journal of Hazardous Materials, 2009, 168, 89-93.
[30] 陳亮妹, 李江遐, 胡兆云, 等. 重金屬低積累作物在農(nóng)田修復(fù)中的研究與應(yīng)用[J]. 作物雜志, 2018(1): 16-24.
CHEN Liangmei, LI Jiangxia, HU Zhaoyun, et al. Review on application of low accumulation crops on remediation of farmland contaminated by heavy metals[J]. Crops, 2018(1): 16-24.
[31] 王丹, 戴紹軍. 植物響應(yīng)金屬脅迫重要蛋白質(zhì)的細(xì)胞定位[J]. 生物技術(shù)通報(bào), 2010(7): 7-13.
WANG Dan, DAI Shaojun. Cellular localization of proteins in plant in response to heavy metals[J]. Biotechnology Bulletin, 2010(7): 7-13.
[32] ZHOU Qin, LIU Zhaodong, LIU Yuan, et al. Relative abundance of chemical forms of Cu(II) and Cd(II) on soybean roots as influenced by pH, cations and organic acids[J]. Scientific Reports, 2016(6): 36373.
[33] 徐紅寧, 楊居榮, 許嘉琳. 作物對(duì)Cd的吸收與根系陽(yáng)離子交換容量[J]. 農(nóng)業(yè)環(huán)境保護(hù), 1995(4): 150-153, 177, 193.
XU Hongning, YANG Jurong, XU Jialin. Cd uptake by crops and root cation exchange capacity[J]. Journal of Agro-Environment Science, 1995(4): 150-153, 177, 193.
[34] 何冠華. 不同基因型小麥對(duì)土壤重金屬污染響應(yīng)及抗性篩選研究[D]. 鄭州: 河南農(nóng)業(yè)大學(xué), 2012.
HE Guanhua. Study on response of different genotypes of wheat to heavy metal pollution soil and resistance screening[D]. Zhengzhou: Henan Agricultural University, 2012.
[35] CHO ShihChueh; CHAO Yunyang, KAO Ching Huei. Calcium deficiency increases Cd toxicity and Ca is required for heat-shock induced Cd tolerance in rice seedlings[J]. Journal of Plant Physiology, 2012, 169(9): 892-898.
[36] 熊禮明, 魯如坤. 幾種物質(zhì)對(duì)水稻吸收鎘的影響及機(jī)理[J]. 土壤, 1992 (4): 197-200.
XIONG Liming, LU Rukun. Effects of several substances on cadmium uptake in rice and its mechanism[J]. Soils, 1992 (4): 197-200.
[37] 朱華蘭. 鎘脅迫下不同鎂水平對(duì)玉米幼苗生長(zhǎng)的影響及生理機(jī)制的研究[D]. 重慶: 西南大學(xué),2013.
ZHU Hualan. Effect of magnesium levels on growth of cornunder cadmium stress and its physiological mechanisms[D]. Chongqing: Southwest University, 2013.
[38] 孫梟瓊, 陳永亮, 孫慎麗, 等. 腐殖酸鈉對(duì)鎘脅迫下冬小麥種子萌發(fā)及根系生長(zhǎng)的影響[J]. 安徽農(nóng)業(yè)科學(xué), 2017, 45(13): 34-35, 71.
SUN Xiaoqiong, CHEN Yongliang, SUN Shenli, et al. Effect of sodium humate on winter wheat seed germination and root growth under cadmium stress[J]. Journal of Anhui Agricultural Sciences, 2017, 45(13): 34-35, 71.
[39] ZHANG Chaochun, WANG Lijun, NIE Qing, et al. Long-term effects of exogenous silicon on cadmium translocation and toxicity in rice (Oryza sativa L.). Environmental and Experimental Botany, 2008, 62(3): 300-307.
[40] 郭磊. 外源硅影響鎘化學(xué)形態(tài)及其生物有效性的土壤化學(xué)機(jī)制[D]. 沈陽(yáng): 沈陽(yáng)農(nóng)業(yè)大學(xué), 2018.
GUO Lei. The soil chemistry mechanisms of influences on cadmium chemical speciation and bioavailability with exogenous silicon[D]. Shenyang: Shenyang Agricultural University, 2018.
[41] 王義超. 硅對(duì)鎘和汞脅迫下大蒜生理生化代謝的影響及機(jī)理研究[D]. 楊凌: 西北農(nóng)林科技大學(xué), 2014.
WANG Yichao. Effects and mechanisms of exogenous silicon on physiological and biochemical metabolisms in garlic under cadmium and mercury stresses[D]. Yangling: Northwest A&F University, 2014.
[42] 蘇秀偉. 硅緩解蘋果植株高錳毒害的研究[D]. 泰安: 山東農(nóng)業(yè)大學(xué), 2011.
SU Xiuwei. The study of silicon alleviating manganese toxicity in apple trees[D]. Taian: Shandong Agricultural University, 2011.
[43] 李樂樂, 劉源, 李寶貴, 等. 鎘低積累小麥品種的篩選研究[J]. 灌溉排水學(xué)報(bào), 2019, 38(8): 53-58, 72.
LI Lele, LIU Yuan, LI Baogui, et al. Screening of low-accumulation wheat varieties with cadmium[J]. Journal of Irrigation and Drainage, 2019, 38(8): 53-58, 72.
Cadmium Accumulation in Wheat of Different Varieties at Seedling Stage as Impacted by Addition of Exogenous Elements
LI Lele2, LI Zhongyang1, WU Dafu2, BAN Zhuohao3, LI Baogui1, FAN Tao1, HU Chao1, ZHAO Zhijuan1, LIU Yuan1*
(1. Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China; 2. Henan Institute of Science and Technology, Xinxiang 453003, China;3. Changyuan Vocational Secondary Professional School, Xinxiang 453400, China)
【】Cadmium (Cd) is one of contaminants found in agricultural soils caused by anthropogenic activities including wastewater irrigation and application of phosphate fertilizers rich in Cd impurities, sludges and composts. In China, Cd contamination comes to the top in soils contaminated by all heavy metals and their metalloids. Since Cd is toxicto all organisms and highly mobile in soil for plants to take up, excessive Cd accumulation in crop tissues could impede its growth and even lead to mortality. Numerous studies showed that adding exogenous substances to soil could alleviate toxic effects of Cd on crops, but if and how their efficacy varies with crop variety remains poorly understood.【】Taking winter wheat as an example, this paper aimed to investigate the effects of exogenous Si, Ca, Mg and humic acid on uptake of Cd by different cultivars and its subsequent translocation at seedling stage.【】Wheat varieties Bainong 419 (419) with high Cd accumulation in grain and Bainong 418 (418) with low Cd accumulation in grain were taken as the model plants. They were grown in hydroponic culture with the Cd content in it spiked to 10 mg/L or 30 mg/L respectively. We added Si, Ca, Mg and humic acid at different rates to the medium and harvested the crops 30 days later. We then measured Cd accumulation and transportation in roots and shoots, as well as root morphology traits.【】Crop absorption of Cd varied with the wheat varieties, and the total length, surface area, volume and tip number of the roots in both varieties decreased with the increase in Cd concentration. Compared to variety 418, variety 419 took more Ca for its root developments. At low Cd concentration and compared to CK, adding Si at low dose improved root growth of the variety 419 and reduced Cd accumulation in its roots and shoots, while adding other elements inhibited root growth; applying humic acid at high dose enhanced Cd accumulation in the roots. It was found that compared to CK, adding any exogenous element reduced Ca content in the roots of the variety 419 when Cd concentration was low. For the variety 418 grown in medium with low Cd concentration, adding Si and Ca was more effective to promote root growth than adding Si alone, while adding Mg and humic acid did not show noticeable effects. Adding Si reduced Cd accumulation in roots and shoots at significant level, while adding Ca and Mg only impeded Cd accumulation in the root. Humic acid did not appear to have a noticeable impact on plant Cd. For the crops growing in medium with high Cd concentration, adding Si boosted root growth of both varieties regardless of its application rate, while in contrast, adding other elements were unable to alleviate Cd toxicity to plants at significant level. Compared with other treatments, adding Si at high does significantly increased the translocation factor (TF) for both varieties growing in medium with low Cd concentration, and it was also effective at boosting the TF for the variety 419 growing in medium with high Cd concentration.【】The most effective conditioner to alleviate Cd toxicity to winter wheat was Si, although its efficacy varies with wheat cultivar, Si application rate and Cd concentration in the medium where the crop grows.
winter wheat; Si; Cd; Ca; Mg; humic acid
X703.5
A
10.13522/j.cnki.ggps.2019467
1672 - 3317(2021)01 - 0079 - 12
2019-12-26
“十三五”國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2017YFD0801103-2);中國(guó)農(nóng)業(yè)科學(xué)院基本科研業(yè)務(wù)費(fèi)專項(xiàng)所級(jí)統(tǒng)籌項(xiàng)目(FIRI2016-14);中國(guó)農(nóng)業(yè)科學(xué)院基本科研業(yè)務(wù)費(fèi)專項(xiàng)院級(jí)統(tǒng)籌項(xiàng)目(Y2016XT02);國(guó)家自然科學(xué)基金青年科學(xué)基金項(xiàng)目(41701265)
李樂樂(1994-),男。碩士研究生,主要從事重金屬污染土壤修復(fù)研究。E-mail: 13939805310@163.com
劉源(1988-),女。副研究員,博士,主要從事非常規(guī)水資源安全利用研究。E-mail: liuyuanfiri88@163.com
李樂樂, 李中陽(yáng), 吳大付, 等. 外源物質(zhì)對(duì)鎘脅迫下不同品種冬小麥苗期鎘吸收特征的影響[J]. 2021, 40(1): 79-90.
LI Lele, LI Zhongyang, WU Dafu, et al. Cadmium Accumulation in Wheat of Different Varieties at Seedling Stage as Impacted by Addition of Exogenous Elements[J]. Journal of Irrigation and Drainage, 2021, 40(1): 79-90.
責(zé)任編輯:趙宇龍