LED補(bǔ)光和根區(qū)加溫對(duì)日光溫室起壟內(nèi)嵌式基質(zhì)栽培甜椒生長(zhǎng)及產(chǎn)量的影響*

傅國(guó)海,楊其長(zhǎng),劉文科

(中國(guó)農(nóng)業(yè)科學(xué)院農(nóng)業(yè)環(huán)境與可持續(xù)發(fā)展研究所/農(nóng)業(yè)部設(shè)施農(nóng)業(yè)節(jié)能與廢棄物處理重點(diǎn)實(shí)驗(yàn)室 北京 100081)

LED補(bǔ)光和根區(qū)加溫對(duì)日光溫室起壟內(nèi)嵌式基質(zhì)栽培甜椒生長(zhǎng)及產(chǎn)量的影響*

傅國(guó)海,楊其長(zhǎng),劉文科**

(中國(guó)農(nóng)業(yè)科學(xué)院農(nóng)業(yè)環(huán)境與可持續(xù)發(fā)展研究所/農(nóng)業(yè)部設(shè)施農(nóng)業(yè)節(jié)能與廢棄物處理重點(diǎn)實(shí)驗(yàn)室 北京 100081)

田間條件下采用起壟內(nèi)嵌式基質(zhì)栽培(soil ridged substrate-embedded cultivation,SRSC)方法,研究了日光溫室LED冠層補(bǔ)光和電熱線根區(qū)加溫對(duì)甜椒生長(zhǎng)和產(chǎn)量的影響。該試驗(yàn)設(shè)不加溫不補(bǔ)光對(duì)照(CK)、根區(qū)加溫15 ℃處理(T15)、根區(qū)加溫18 ℃處理(T18)、單一補(bǔ)光處理(L)、根區(qū)加溫15 ℃+補(bǔ)光處理(T15+L)、根區(qū)加溫18 ℃+補(bǔ)光處理(T18+L),共6個(gè)處理。結(jié)果表明,與對(duì)照相比,根區(qū)加溫均能提高SRSC甜椒根區(qū)的溫度,但根區(qū)溫度仍呈現(xiàn)出隨環(huán)境溫度變化而變化的趨勢(shì),T18的根區(qū)全天保持較高溫度。根區(qū)熱通量的變化與根區(qū)溫度變化相對(duì)應(yīng),T15和T18處理的根區(qū)熱通量晝夜變化較CK劇烈,其根區(qū)側(cè)面白天向內(nèi)傳熱滯后,晚間側(cè)面向外傳熱提前,傳遞量增加; 根區(qū)垂直方向白天向內(nèi)傳熱滯后,傳遞量減少,晚間垂直向外傳熱提前,但傳遞量增加。T15和T18均顯著提高了甜椒的株高、冠層厚度和冠層直徑,且T18比T15效果更明顯。T15對(duì)甜椒的地上及地下干鮮重沒(méi)有顯著的提升作用,而 T18的提升效果顯著。根區(qū)加溫補(bǔ)光處理的甜椒生物量普遍高于單一根區(qū)加溫或補(bǔ)光處理,其中T18+L處理提升效果顯著優(yōu)于T15+L處理。T15、T18和L相對(duì)CK均提高了甜椒單產(chǎn),單產(chǎn)分別提高30.74%、53.0%和14.81%。而根區(qū)加溫和LED補(bǔ)光協(xié)同作用比單一的根區(qū)加溫或冠層補(bǔ)光都能表現(xiàn)更好的增產(chǎn)效果,T15+L和 T18+L分別比 T15和 T18的產(chǎn)量分別提升 32.86%和15.50%,分別比L產(chǎn)量提升51.29%和53.87%?？傊?根區(qū)加溫與LED補(bǔ)光是日光溫室甜椒增產(chǎn)有效的調(diào)控措施,兩者在增加單株產(chǎn)量上存在顯著的協(xié)同效應(yīng),二者共同作用比單一作用效果更加明顯,且根區(qū)加溫對(duì)甜椒生長(zhǎng)和產(chǎn)量的促進(jìn)效果比冠層補(bǔ)光更加顯著,在實(shí)際生產(chǎn)中具有重要的指導(dǎo)意義。

起壟內(nèi)嵌式基質(zhì)栽培; 日光溫室; 根區(qū)加溫; LED補(bǔ)光; 甜椒; 產(chǎn)量

日光溫室因其具有良好的蓄熱保溫和節(jié)能高效的性能[1],在一定程度上解決了我國(guó)北方冬季蔬菜生產(chǎn)問(wèn)題,得到大面積的推廣應(yīng)用[2]。目前,我國(guó)日光溫室栽培面積已超過(guò)1×106hm2,約占設(shè)施園藝栽培面積的 25%,成為北方地區(qū)設(shè)施蔬菜生產(chǎn)中最為重要的設(shè)施類(lèi)型[3]。日光溫室多以傳統(tǒng)的土壤栽培為主,這種栽培方式不僅產(chǎn)量低和連作障礙嚴(yán)重,而且存在諸多生產(chǎn)問(wèn)題。比如,土壤栽培過(guò)程中過(guò)量的水肥和農(nóng)藥投入,會(huì)導(dǎo)致資源浪費(fèi)和生態(tài)環(huán)境污染[4-5]。而且,在冬春季日光溫室蔬菜生產(chǎn)中,低溫脅迫和光照不足是影響作物生長(zhǎng)的重要環(huán)境因素[6-7]。日光溫室一般無(wú)溫度調(diào)控設(shè)備,在冬季極端低溫環(huán)境下溫室內(nèi)作物光合作用等一系列生理活動(dòng)受到抑制,導(dǎo)致生長(zhǎng)減緩和產(chǎn)量降低[8-9]。研究表明,根區(qū)溫度對(duì)作物生長(zhǎng)的影響比空氣溫度更大[10]。根區(qū)溫度降低影響根系呼吸、水肥吸收、根系生長(zhǎng)及作物移植后存活[11-12],嚴(yán)重阻礙作物開(kāi)花結(jié)果[13]。光是作物生長(zhǎng)發(fā)育重要的環(huán)境因子,對(duì)植物的形態(tài)建成、生理代謝、光周期反應(yīng)、生長(zhǎng)發(fā)育及果實(shí)品質(zhì)有廣泛的調(diào)節(jié)作用[14-15]。在冬季和早春季節(jié),太陽(yáng)高度角低,日照時(shí)間短,溫室弱光造成光合作用減弱和物質(zhì)合成障礙,最終影響產(chǎn)量和品質(zhì)[16]。

針對(duì)日光溫室栽培過(guò)程中出現(xiàn)的冬季低溫脅迫和土壤栽培帶來(lái)的低產(chǎn)及一系列環(huán)境問(wèn)題,本課題組以提高晚間日光溫室作物根區(qū)溫度和提升產(chǎn)量為目標(biāo),基于土壤栽培根區(qū)環(huán)境穩(wěn)定與基質(zhì)栽培高產(chǎn)的優(yōu)點(diǎn)提出了一種新的栽培方法——起壟內(nèi)嵌式基質(zhì)栽培方法[17](soil ridged substrate-embedded cultivation,SRSC)。前期的研究表明,相對(duì)土壟栽培,在早春低溫環(huán)境下采用起壟內(nèi)嵌式基質(zhì)栽培方法進(jìn)行甜椒栽培,能夠提高夜間最低根區(qū)溫度2.15 ,℃ 提高甜椒產(chǎn)量50%以上[18-19]。雖然SRSC栽培方法能夠有效提高根區(qū)溫度,但是在應(yīng)對(duì)低溫脅迫方面還是有一定的不足。Miao等[20]研究表明,早晨溫室空氣溫度可從12 ℃迅速升高到30 ,℃ 而根區(qū)溫度則維持在10 ℃左右,即根區(qū)溫度的變化相對(duì)空氣溫度具有滯后性。當(dāng)空氣溫度適合作物生長(zhǎng)時(shí),根區(qū)溫度脅迫成了抑制根區(qū)生理活動(dòng)和植物生長(zhǎng)發(fā)育的主要因素[21-23]。此外,根區(qū)加溫能使作物生長(zhǎng)所需溫室環(huán)境比傳統(tǒng)加溫條件低5～10 ℃[24]。曲梅等[25]發(fā)現(xiàn),根區(qū)加溫通過(guò)局部調(diào)控比空氣加溫節(jié)約能耗28%左右,生產(chǎn)投入較少。因此,通過(guò)外源人工根區(qū)加溫對(duì)作物生長(zhǎng)促進(jìn)和產(chǎn)量提高的效果更加明顯且更加節(jié)能高效,這對(duì)應(yīng)對(duì)冬季低溫脅迫具有重要的研究?jī)r(jià)值,且能夠?qū)崿F(xiàn)農(nóng)業(yè)的可持續(xù)發(fā)展。

冬季日光溫室生產(chǎn)中面臨的另一重要問(wèn)題是弱光寡照。針對(duì)設(shè)施園藝生產(chǎn)中光照不足的現(xiàn)象,冠層人工補(bǔ)光在設(shè)施栽培過(guò)程中應(yīng)用已較為廣泛。有研究表明,苗期補(bǔ)光對(duì)蔬菜壯苗的形成具有促進(jìn)作用[26],對(duì)提高作物品質(zhì)和產(chǎn)量形成有著重要意義。目前,關(guān)于日光溫室冬春季生產(chǎn)過(guò)程中的冬季根區(qū)加溫與LED人工補(bǔ)光的研究報(bào)道較少,協(xié)同機(jī)制仍不清楚。本研究旨在探究根區(qū)加溫、冠層補(bǔ)光對(duì)甜椒(Capsicum annuumL.)苗生長(zhǎng)和產(chǎn)量的影響,為日光溫室的根區(qū)加溫和LED補(bǔ)光提供科學(xué)依據(jù)。

1 材料與方法

1.1 試驗(yàn)材料

試驗(yàn)在北京市順義區(qū)大孫各莊鎮(zhèn)的日光溫室中進(jìn)行,溫室長(zhǎng)60 m,跨度8 m,脊高3.8 m。試驗(yàn)小區(qū)長(zhǎng)15 m,寬3 m,小區(qū)距溫室最南端1 m,距西側(cè)山墻4 m。供試作物為甜椒(Capsicum annuumL.),品種為‘海豐 16號(hào)’,穴盤(pán)育苗,三葉一心時(shí)定植,株距30 cm,行距90 cm,定植時(shí)間為2015年11月20日。試驗(yàn)甜椒栽培采用起壟內(nèi)嵌式基質(zhì)栽培方式,即將特別設(shè)計(jì)的基質(zhì)栽培槽(鐵絲網(wǎng)槽內(nèi)嵌塑料薄膜,長(zhǎng)×寬×高=120 cm×10 cm×15 cm)嵌在一定規(guī)格的土壟中,槽內(nèi)裝入按比例混合均勻的栽培基質(zhì)(草炭∶蛭石∶珍珠巖=1∶1∶1),外側(cè)土壤培壟完成后,壟表覆蓋地膜,完成培壟(橫截面為梯形,上底 20 cm,下底40 cm,高15 cm)。試驗(yàn)采用全營(yíng)養(yǎng)液滴灌的方法栽培甜椒。栽培壟根區(qū)加溫采用地下埋置電熱線的方法,電熱線規(guī)格為450 W·(30m)-1,埋于地下2 cm處,埋置好后覆土,其上設(shè)置栽培壟,通過(guò)控溫儀和定時(shí)器進(jìn)行加溫時(shí)間和溫度控制; 甜椒幼苗冠層補(bǔ)光采用LED植物補(bǔ)光燈(PPFD=200 μmol·m-2·s-1,R∶B=7∶3,光強(qiáng)為實(shí)際測(cè)得,測(cè)定位點(diǎn)為幼苗冠層頂端),LED植物補(bǔ)光燈條狀布置,懸吊于甜椒幼苗上方,距離冠層30 cm,與栽培壟走向一致,補(bǔ)光時(shí)間通過(guò)定時(shí)器進(jìn)行控制。試驗(yàn)裝置見(jiàn)圖1。

圖1 土壟內(nèi)嵌基質(zhì)栽培方法栽培壟結(jié)構(gòu)和溫度、熱通量測(cè)點(diǎn)示意圖Fig.1 Sketch map of soil ridge substrate-embedded cultivation ridge and measuring points of temperature and heat flux

1.2 試驗(yàn)設(shè)計(jì)

試驗(yàn)共設(shè)置 6個(gè)處理,探究根區(qū)加溫和冠層補(bǔ)光對(duì)甜椒幼苗生長(zhǎng)的影響。甜椒根區(qū)加溫設(shè)置15 ℃和18 ℃兩個(gè)溫度梯度,根區(qū)加溫時(shí)間為4:00—8:00;甜椒冠層LED補(bǔ)光時(shí)間為4:00—8:00,甜椒根區(qū)加溫與冠層補(bǔ)光時(shí)段保持一致。處理 1為對(duì)照栽培壟(CK),不進(jìn)行根區(qū)加溫和冠層補(bǔ)光處理; 處理 2為根區(qū)加溫15 ℃處理(T15); 處理3為根區(qū)加溫18 ℃處理(T18); 處理4為冠層補(bǔ)光處理(L); 處理5為根區(qū)加溫15 ℃和冠層補(bǔ)光處理(T15+L); 處理6為根區(qū)加溫18 ℃和冠層補(bǔ)光處理(T18+L)。每個(gè)處理設(shè)置3個(gè)重復(fù)栽培行,每行栽種6株甜椒,各處理行自東向西依次排列,各重復(fù)行隨機(jī)排列,栽培過(guò)程中各處理水肥管理一致。根區(qū)加溫和LED補(bǔ)光時(shí)間為2015年12月10日至2016年2月25日,補(bǔ)光處理與不補(bǔ)光處理隔離,避免干擾。

1.3 收獲與測(cè)定指標(biāo)

室外最低氣溫為-5 ℃左右,日光溫室室內(nèi)氣溫及甜椒根區(qū)溫度較低。試驗(yàn)開(kāi)始后,在甜椒幼苗期進(jìn)行試驗(yàn)數(shù)據(jù)采集,開(kāi)始時(shí)間為2015年12月10日。采用國(guó)產(chǎn) YM-CJ型智能土壤溫度記錄儀(記錄儀精度±0.05 )℃采集甜椒根區(qū)的溫度及室內(nèi)、外空氣溫度。甜椒根區(qū)溫度測(cè)點(diǎn)位于壟中心位置10 cm深處(圖1),室內(nèi)溫度測(cè)點(diǎn)位于試驗(yàn)小區(qū)上方 2 m高處,測(cè)點(diǎn)避光; 室外溫度測(cè)點(diǎn)位于室外通風(fēng)避光處,數(shù)據(jù)采集時(shí)間間隔為10 min。選定2015年12月12—14日3 d的根區(qū)溫度數(shù)據(jù)進(jìn)行分析。采用國(guó)產(chǎn)YM-RT型土壤熱通量采集器采集 SRSC栽培壟側(cè)面土壤-基質(zhì)界面及根區(qū)中心(10 cm深)垂直方向的熱通量(圖1),熱量向根區(qū)內(nèi)部傳遞為正值,反之則為負(fù)值,選定2016年1月30日—2月1日以及2016年2月12—14日兩個(gè)時(shí)間段內(nèi)的根區(qū)側(cè)面及垂直方向的熱通量進(jìn)行分析。2016年3月20日甜椒采收時(shí),測(cè)定甜椒幼苗的生長(zhǎng)及產(chǎn)量指標(biāo),采用游標(biāo)卡尺測(cè)定莖粗和果實(shí)大小,采用直尺測(cè)定甜椒株高和冠層寬度及高度,采用天平測(cè)定甜椒生物量及產(chǎn)量,產(chǎn)量分兩次測(cè)定,分別為3月20日和3月30日。

1.4 數(shù)據(jù)分析

數(shù)據(jù)采用 Microsoft Excel軟件處理及作圖,并采用SAS 8.2軟件進(jìn)行數(shù)據(jù)分析。

2 結(jié)果與分析

2.1 試驗(yàn)期間日光溫室內(nèi)外及根區(qū)溫度變化規(guī)律

試驗(yàn)期間日光溫室內(nèi)外溫度分別為 6～30 ℃和-11～12 ℃。由圖2a可知,根區(qū)加溫階段室外氣溫變化范圍為-7～8 ,℃ 而室內(nèi)最低氣溫僅為8 ,℃ 平均溫度為12.7 ℃。由圖2b可知,根區(qū)加溫能夠改變根區(qū)溫度的變化規(guī)律。日光溫室內(nèi)根區(qū)溫度在 15:00左右達(dá)到峰值,在10:00左右達(dá)到最低。對(duì)照處理的根區(qū)溫度隨時(shí)間變化表現(xiàn)出有規(guī)律的升高和降低,一天之中各有1個(gè)峰值和谷值。根區(qū)加溫15 ℃的根區(qū)溫度變化在后兩天表現(xiàn)出不同,而第 1天根區(qū)溫度無(wú)明顯不同可能是由于根區(qū)溫度較高,未達(dá)到加溫條件,加熱系統(tǒng)未啟動(dòng)。后兩天,根區(qū)溫度低于設(shè)定值加溫系統(tǒng)啟動(dòng),根區(qū)溫度在4:00開(kāi)始升高,7:00達(dá)到峰值后與對(duì)照處理一樣開(kāi)始下降,可能是由于7:00之后加溫補(bǔ)償?shù)臒崃坎患吧⑹У臒崃慷?但是降低了溫度下降速度,且能夠相對(duì)保持較高的根區(qū)溫度。根區(qū)加溫18 ℃處理根區(qū)溫度變化較為一致。根區(qū)溫度在4:00開(kāi)始升高,表現(xiàn)出先升高后降低的變化規(guī)律,在 9:00左右達(dá)到峰值,這與加溫到 8:00不一致,可能是由于儲(chǔ)存的熱量會(huì)繼續(xù)提高根區(qū)溫度,到9:00熱量已不足以維持散熱,溫度開(kāi)始下降,但其溫度水平較高。

圖2 甜椒根區(qū)加溫階段日光溫室內(nèi)、外氣溫(a)及不同加溫條件下甜椒根區(qū)溫度變化(b)Fig.2 Air temperatures inside and outside solar greenhouse during root zone heating period of sweet pepper (a) and changes of root zone temperatures of sweet pepper under different heating conditions (b)

2.2 單獨(dú)根區(qū)加溫條件下甜椒根區(qū)水平與垂直熱通量變化規(guī)律

由圖3a可知,對(duì)照與兩種加溫條件下甜椒根區(qū)側(cè)面熱通量變化不同。選取第 3天晴天時(shí)的數(shù)據(jù)進(jìn)行分析。根據(jù)熱通量板的放置方向,正值表示熱量向內(nèi)傳遞,負(fù)值表示熱量向外傳遞。根據(jù)曲線的變化趨勢(shì)可知,白天熱量向內(nèi)傳遞,夜晚熱量向外傳遞,且三者表現(xiàn)出一定的規(guī)律性。隨著根區(qū)加溫梯度的升高,各處理的根區(qū)溫度與外界溫差逐漸增加,白天根區(qū)側(cè)面向內(nèi)部傳遞的最大熱通量遞增,傳遞越劇烈,分別是43.9 W·m-2、49.1 W·m-2和54.9 W·m-2,而夜間由于氣溫快速降低,各處理向外側(cè)傳遞的最大熱通量也遞增,分別是7.2 W·m-2、11.8 W·m-2和12.6 W·m-2,這與根區(qū)不同加溫梯度導(dǎo)致的根區(qū)溫度與外界環(huán)境溫差有關(guān)。

圖3 不同加溫條件下甜椒根區(qū)側(cè)面(a)和垂直方向(b)熱通量變化Fig.3 Changes of heat fluxes of lateral (a) and vertical (b) root zones of sweet pepper under different heating conditions

由圖3b可知,對(duì)照與兩種加溫條件下甜椒根區(qū)垂直方向的熱通量變化不同。根據(jù)熱通量板的放置方向,正值表示熱量向內(nèi)傳遞,負(fù)值表示熱量向外傳遞。選取第3天晴天的數(shù)據(jù)進(jìn)行分析。隨著根區(qū)加溫梯度的升高,白天向根區(qū)內(nèi)部傳遞最大熱通量差異較小,但根區(qū)加溫處理提前達(dá)到峰值,比不加溫處理提前 2 h,而夜間向外傳遞的最大熱通量隨著加溫梯度的升高遞增,但相差較小。隨著根區(qū)加溫梯度的提高,根區(qū)側(cè)面垂直方向的熱量傳遞表現(xiàn)出較為一致的規(guī)律,根區(qū)早晨外部開(kāi)始向內(nèi)傳熱的時(shí)間逐漸滯后,而晚上基質(zhì)開(kāi)始向外側(cè)土壤傳熱的時(shí)間逐漸提前,這可能是由于栽培壟蓄積的熱量不同于氣溫變化造成的。其中,隨著根區(qū)加溫梯度的提高,根區(qū)側(cè)面白天和夜間的傳熱量增加,而根區(qū)垂直方向的白天傳熱量減少,夜間的傳熱量增加。

2.3 根區(qū)加溫和LED補(bǔ)光對(duì)甜椒生長(zhǎng)指標(biāo)的影響

由表 1可知,不同加溫補(bǔ)光處理下,甜椒的形態(tài)指標(biāo)表現(xiàn)出差異。根區(qū)加溫15 ℃和18 ℃均提高了甜椒的株高、莖粗、冠層高度和冠層直徑,其中甜椒的株高、冠層厚度和冠層直徑提高顯著(冠層厚度是指甜椒冠部分枝的厚度,冠層直徑指冠部分枝的直徑,這兩個(gè)指標(biāo)表征地上部光合作用部分的形態(tài)),且根區(qū)加溫18 ℃比15 ℃效果更明顯,除莖粗外,根區(qū)加溫18 ℃甜椒指標(biāo)顯著高于加溫15 ℃。單一冠層補(bǔ)光處理的甜椒株高和冠層直徑得到顯著提高,但莖粗和冠層厚度提升不顯著。在根區(qū)加溫的基礎(chǔ)上進(jìn)行冠層補(bǔ)光處理會(huì)進(jìn)一步提高甜椒的形態(tài)指標(biāo),兩種根區(qū)加溫方式下甜椒的冠層直徑均顯著提高。同時(shí),根區(qū)加溫18 ℃條件下補(bǔ)光,還會(huì)顯著提高株高和冠層厚度。相比之下,根區(qū)加溫對(duì)甜椒生長(zhǎng)的影響比冠層補(bǔ)光更加顯著。

不同根區(qū)加溫和冠層補(bǔ)光條件下甜椒的生物量出現(xiàn)差異,能夠增加甜椒地上及地下的生物量。根區(qū)加溫15 ℃對(duì)甜椒地上及地下干、鮮重?zé)o顯著提升作用,而根區(qū)加溫18 ℃的提升效果顯著。單一的冠層補(bǔ)光對(duì)甜椒地上干重和地下鮮重的提高效果顯著,這可能是由于物質(zhì)運(yùn)輸失衡引起的。根區(qū)加溫和冠層補(bǔ)光協(xié)同處理的甜椒生物量普遍高于單一根區(qū)加溫處理,其中根區(qū)加溫18 ℃處理提升效果顯著優(yōu)于加溫15 ℃處理。

表1 不同加溫補(bǔ)光條件下甜椒的形態(tài)和生物量指標(biāo)(n=6)Table 1 Morphological parameters of sweet pepper under different heating and lighting conditions

2.4 根區(qū)加溫和LED補(bǔ)光對(duì)甜椒產(chǎn)量的影響

由表2可知,根區(qū)加溫和冠層補(bǔ)光均能提高甜椒的產(chǎn)量。根區(qū)加溫15 ℃和18 ℃處理的果實(shí)大小、果實(shí)數(shù)量、單果重等指標(biāo)未顯著提高,但單株產(chǎn)量得到顯著提升,且根區(qū)加溫18 ℃比加溫15 ℃顯著提高了單株產(chǎn)量。T15和T18處理的甜椒單產(chǎn)分別比CK提高30.74%和53.00%。單一冠層補(bǔ)光對(duì)產(chǎn)量指標(biāo)均無(wú)顯著提升作用,單產(chǎn)量比CK提升14.81%。在根區(qū)加溫的基礎(chǔ)上進(jìn)行冠層補(bǔ)光會(huì)進(jìn)一步提升甜椒的產(chǎn)量指標(biāo)。根區(qū)加溫和冠層補(bǔ)光協(xié)同作用比單一的根區(qū)加溫或冠層補(bǔ)光都能表現(xiàn)更好的增產(chǎn)效果。根區(qū)加溫和冠層補(bǔ)光協(xié)同作用能夠比單一根區(qū)加溫處理更加顯著的地提高產(chǎn)量。其中T15+L相對(duì)于T15的增產(chǎn)效果要比T18+L相對(duì)于T18的增產(chǎn)效果更優(yōu),在果實(shí)數(shù)量和單果重上表現(xiàn)顯著。T15+L和T18+L處理比單一加溫條件下的產(chǎn)量分別提升32.86%和15.50%,分別比 L處理的甜椒產(chǎn)量提升 51.29%和 53.87%,而T18+L比T15+L的產(chǎn)量提升1.7%,增產(chǎn)效果不明顯。

表2 不同加溫補(bǔ)光條件下的甜椒產(chǎn)量指標(biāo)(n=6)Table 2 Yield parameters of sweet pepper under different heating and lighting conditions

3 結(jié)論與討論

日光溫室SRSC栽培的甜椒具有高產(chǎn)潛力,但受控于低溫弱光逆境危害,造成減產(chǎn)。本試驗(yàn)結(jié)果表明,氣溫較低的環(huán)境條件下,根區(qū)加溫和LED補(bǔ)紅藍(lán)光能夠促進(jìn)日光溫室SRSC栽培甜椒的生長(zhǎng)并增加其產(chǎn)量,說(shuō)明在冬季日光溫室SRSC方法應(yīng)用生產(chǎn)過(guò)程中,根區(qū)加溫和LED補(bǔ)光能夠進(jìn)一步提升其生產(chǎn)性能。

SRSC根區(qū)加溫能夠改變甜椒根區(qū)的溫?zé)嶙兓?guī)律,且較高的根區(qū)加溫溫度對(duì)根區(qū)溫度和熱通量變化影響較大。研究發(fā)現(xiàn),冬季日光溫室環(huán)境最低溫出現(xiàn)在6:00左右,而土壤或栽培壟的溫度變化相對(duì)環(huán)境溫度的變化具有滯后性[18,27]。溫室空氣溫度在早晨可以迅速升高,但是根區(qū)溫度升溫慢,此時(shí),低根區(qū)溫度是寒冷季節(jié)影響植物生長(zhǎng)和生理活動(dòng)的關(guān)鍵環(huán)境因素[23]。我們選擇在根區(qū)溫度較低的4:00—8:00進(jìn)行根區(qū)加溫,在最為有效的時(shí)間內(nèi)加溫實(shí)現(xiàn)節(jié)能和高效。可以發(fā)現(xiàn),根區(qū)加溫18 ℃造成根區(qū)溫度全天都高于對(duì)照,這可能是由于加溫時(shí)段蓄積了較多的熱量,而根區(qū)加溫15 ℃提升了低溫時(shí)段的根區(qū)溫度和白天升溫階段的根區(qū)溫度,提升幅度弱于根區(qū)加溫18 ℃處理,說(shuō)明其根區(qū)沒(méi)有蓄積太多的熱量。同時(shí)發(fā)現(xiàn),在加溫階段兩種處理根區(qū)溫度都有一個(gè)降低過(guò)程,這可能是由于當(dāng)環(huán)境溫度出現(xiàn)極低溫時(shí),影響根區(qū)溫度的變化,引起根區(qū)溫度相對(duì)較大幅度的下降,當(dāng)白天升溫開(kāi)始時(shí),根區(qū)溫度又恢復(fù)上升趨勢(shì)。由于根區(qū)溫度的變化與熱量有著密切的關(guān)系,直接受熱量的影響,但是由于栽培壟側(cè)面土壤和垂直方向基質(zhì)的傳熱速率不同,造成不同加溫處理白天和夜間兩個(gè)部位傳熱散熱的時(shí)間不同。根區(qū)早晨外部開(kāi)始向內(nèi)傳熱的時(shí)間逐漸滯后,而晚上基質(zhì)開(kāi)始向外側(cè)土壤傳熱的時(shí)間逐漸提前,這可能是由于栽培壟溫度較高,而早晨和夜間室內(nèi)氣溫降低較快,造成了熱平衡出現(xiàn)時(shí)間的差異。其中,隨著根區(qū)加溫梯度的提高,根區(qū)內(nèi)部熱量較高,而氣溫變化較為劇烈,加溫處理需向內(nèi)和向外傳遞更多的熱量才能達(dá)到熱量平衡。而垂直方向白天向內(nèi)傳遞熱量較少可能是由于基質(zhì)的傳熱速率較快造成的,栽培壟內(nèi)外沒(méi)有形成明顯的溫度差。

SRSC根區(qū)加溫和冠層補(bǔ)光都能影響甜椒的生長(zhǎng)。根區(qū)加溫通過(guò)改變根區(qū)環(huán)境溫度來(lái)影響根系和冠層的一系列生理活動(dòng)進(jìn)而影響作物的生長(zhǎng)[28-29]。研究表明,低溫條件下根區(qū)加溫能夠促進(jìn)根系呼吸,提高根系代謝活力及其對(duì)水分和養(yǎng)分的吸收[30-31]。此外,根區(qū)加溫還能促進(jìn)冠層的光合作用,有利于物質(zhì)的轉(zhuǎn)運(yùn)[32]。作物冠層補(bǔ)光有利于光合作用的進(jìn)行。冬季日照時(shí)間縮短,光照不足,會(huì)影響作物的光合作用,進(jìn)而影響干物質(zhì)的形成,減少產(chǎn)量[33]。通過(guò)人工補(bǔ)光能夠有效增加光照,促進(jìn)作物光合作用。與溫室低溫環(huán)境中的根區(qū)加溫效果一樣,選擇在揭開(kāi)保溫被前4 h進(jìn)行補(bǔ)光,使作物提前進(jìn)行光合作用,與根區(qū)加溫共同作用,效果比單一根區(qū)加溫或冠層補(bǔ)光好,進(jìn)一步促進(jìn)了作物生長(zhǎng)?？梢园l(fā)現(xiàn),根區(qū)加溫效果比冠層補(bǔ)光效果更好,對(duì)生長(zhǎng)和產(chǎn)量的影響更顯著。

SRSC根區(qū)加溫和冠層補(bǔ)光能夠增加作物產(chǎn)量。這說(shuō)明在 SRSC基礎(chǔ)上進(jìn)行根區(qū)加溫和冠層補(bǔ)光對(duì)產(chǎn)量的提升是有效的,即根區(qū)加溫和冠層補(bǔ)光促進(jìn)了作物生長(zhǎng),能夠增加干物質(zhì)的積累,進(jìn)而增加作物產(chǎn)量。根區(qū)加溫時(shí)段的冠層補(bǔ)光,一方面根區(qū)加溫促進(jìn)了甜椒根系的養(yǎng)分吸收,提高了低溫環(huán)境下甜椒冠層的光合能力,另一方面補(bǔ)光增長(zhǎng)了光合作用時(shí)間,促進(jìn)了甜椒的生長(zhǎng)發(fā)育。此外,有研究表明,根區(qū)加溫調(diào)控根區(qū)局部,比冠層加溫更加節(jié)能[25],且由于作物對(duì)根區(qū)溫度的反應(yīng)更加敏感,根區(qū)加溫更加節(jié)能高效[34]。因此選擇根區(qū)加溫是較為高效的作物調(diào)節(jié)方式。本研究表明,隨著根區(qū)加溫梯度的提升,產(chǎn)量逐漸升高。而根區(qū)加溫配合冠層補(bǔ)光處理甜椒產(chǎn)量高于單一根區(qū)加溫或冠層補(bǔ)光處理,且根區(qū)加溫比冠層補(bǔ)光效果好,但是根區(qū)加溫 18 ℃+ LED補(bǔ)充的產(chǎn)量?jī)H比根區(qū)加溫 15 ℃+LED補(bǔ)光高1.7%,在增加耗能的基礎(chǔ)上,產(chǎn)量并沒(méi)有得到較大的提升。因此從最終的經(jīng)濟(jì)效益考慮,選擇根區(qū)加溫15 ℃和冠層補(bǔ)光效果最優(yōu)。

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Effect of LED supplemental lighting and root zone heating on growth and yield of soil ridged substrate-embedded sweet pepper in solar greenhouses in China*

FU Guohai,YANG Qichang,LIU Wenke**
(Institute of Environment and Sustainable Agricultural Development,Chinese Academy of Agricultural Sciences /Key Laboratory of Energy Conservation and Waste Management of Agricultural Structures,Ministry of Agriculture,Beijing 100081,China)

In order to deal with resource and environmental issues of soil cultivation and sunlight deficiency and to enhanceroot-zone temperature for crop cultivation during low winter temperature periods in solar greenhouses in China,a field study was conducted with soil-ridged substrate-embedded cultivation (SRSC) method under greenhouse conditions to investigate the effect of root-zone heating and LED supplemental lighting on the growth and yield of sweet pepper.Six treatments were designed in the study,including the control without heating and lighting (CK),root zone heating at 15 ℃ (T15),root zone heating at 18 ℃ (T18),sole LED supplemental lighting (L),root zone heating at 15 ℃ plus LED supplemental lighting (T15+L) and root zone heating at 18 ℃ plus LED supplemental lighting (T18+L).The results showed that compared with CK,heating increased the root zone temperature under SRSC and root zone temperature changed with change in temperature of the environment.Root zone temperature under T18 was high throughout the day.Heat flux under T15 and T18 fluctuated with root zone heating and changed more violently than under CK.The data showed a lag in the time of inward heat transfer and an advance in the time of outward heat transfer with increasing root zone temperature in lateral and vertical directions,and there was more diurnal heat transfer in the vertical root zone.T15 and T18 treatments significantly increased plant height,canopy height and diameter of sweet pepper,which were more obvious under T18 than T15 treatments.The growth parameters of sweet pepper further improved with simultaneous root zone heating and LED supplemental lighting.Fresh and dry shoot and root weights of sweet pepper increased significantly under T18 than under T15 treatment.Plant biomass under simultaneous root zone heating and LED supplemental lighting was higher than that under root zone heating or sole LED supplemental lighting,and that under T18+L treatment was highest.Compared with CK,T15,T18 and L treatments improved sweet pepper yield by 30.74%,53.0% and 14.81%,respectively.Furthermore,sweet pepper yield under T15+L and T18+L were respectively 32.86% and 15.50% higher than that under T15 and T18 and also 51.29% and 53.87% higher than that under L treatment.In summary,root zone heating and LED supplemental lighting proved to be beneficial agronomical soil cultivation measures in solar greenhouse conditions in China with high vegetable productivity and remarkably synergistic effect on single plant yield of sweet pepper.The interaction of root zone heating and LED supplemental lighting was more obvious than that of the single effect of the treatments.Also the effect of root zone heating on the growth and yield of sweet pepper was more obvious than that of LED supplemental lighting.The results of the study provided an important guide in actual crop production under solar greenhouse conditions in China.

Soil ridged substrate-embedded cultivation; Solar greenhouse; Root zone heating; LED supplemental lighting; Sweet pepper; Yield

S625.4

: A

: 1671-3990(2017)02-0230-09

10.13930/j.cnki.cjea.160741

傅國(guó)海,楊其長(zhǎng),劉文科.LED補(bǔ)光和根區(qū)加溫對(duì)日光溫室起壟內(nèi)嵌式基質(zhì)栽培甜椒生長(zhǎng)及產(chǎn)量的影響[J].中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào),2017,25(2): 230-238

Fu G H,Yang Q C,Liu W K.Effect of LED supplemental lighting and root zone heating on growth and yield of soil ridged substrate-embedded sweet pepper in solar greenhouses in China[J].Chinese Journal of Eco-Agriculture,2017,25(2): 230-238

* “十二五”國(guó)家高技術(shù)研究發(fā)展計(jì)劃(863計(jì)劃)課題(2013AA103001)、“十三五”國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目課題(2016YFD0801001)和山東省重點(diǎn)研發(fā)計(jì)劃(2015GGA07003)資助

** 通訊作者: 劉文科,主要從事設(shè)施園藝營(yíng)養(yǎng)與光溫調(diào)控工程方面的研究工作。E-mail: liuwenke@caas.cn

傅國(guó)海,主要從事設(shè)施作物根區(qū)環(huán)控技術(shù)方面的研究工作。E-mail: haifengzhisheng@126.com

2016-08-22 接受日期: 2016-12-05

* Supported by the National High-tech R&D Program of China (863 Program)(2013AA103001),the National Key Research and Development

Project of China (2016YFD0801001) and the Key Research and Development Program of Shandong Province (2015GGA07003)

** Corresponding author,E-mail: liuwenke@caas.cn

Received Aug.22,2016; accepted Dec.5,2016