劉 夢(mèng) 張 垚 葛均筑,* 周寶元 吳錫冬 楊永安 侯海鵬

不同降雨年型施氮量與收獲期對(duì)夏玉米產(chǎn)量及氮肥利用效率的影響

劉 夢(mèng)1張 垚1葛均筑1,*周寶元2吳錫冬1楊永安3侯海鵬4

1天津農(nóng)學(xué)院農(nóng)學(xué)與資源環(huán)境學(xué)院，天津 300384；2中國農(nóng)業(yè)科學(xué)院作物科學(xué)研究所，北京 100081；3天津市優(yōu)質(zhì)農(nóng)產(chǎn)品開發(fā)示范中心，天津 301500；4天津市農(nóng)業(yè)發(fā)展服務(wù)中心，天津 300061

為探討施氮量與收獲期對(duì)華北平原熱量資源限制區(qū)夏玉米籽粒灌漿與脫水、產(chǎn)量形成及氮素利用效率的調(diào)控效應(yīng), 本研究采用二因素區(qū)組試驗(yàn)設(shè)計(jì), 因素公頃施氮量為0 (N0)、120 kg (N120, 2021)、180 kg (N180)、240 kg (N240)、300 kg (N300)、360 kg (N360)和450 kg (N450, 2020), 因素收獲期設(shè)為傳統(tǒng)收獲(normal harvest, NH)和延遲收獲(delayed harvest, DH), 測(cè)定干物質(zhì)積累量(dry matter accumulation, DM)、籽粒灌漿與脫水、產(chǎn)量(grain yield, GY)及其構(gòu)成因素、氮肥偏生產(chǎn)力(nitrogen partial factor productivity, PFPN)和農(nóng)學(xué)利用效率(nitrogen agronomic use efficiency, ANUE)。與干旱年型(2020年)相比, 豐水年型(2021年) DM和粒重(grain weight, GW)顯著下降16.3%～81.5%和2.1%～28.1%, 穗粒數(shù)(ear grains number, EGN)顯著減少44.7%～47.4%, 導(dǎo)致GY、PFPN和ANUE顯著降低31.4%～58.3%、27.2%～30.0%和2.9%～18.0%。與N0相比, 施氮顯著提高DM, GW提高14.6～82.1 mg grain–1, 最大灌漿速率(maximum grain filling rate,max)及其生長量(weight increment ofmax,max)提高0.2～3.4 mg (grain d)–1和10.4～44.1 mg grain–1, 到達(dá)max時(shí)期(time reaching themax,max)提前0.4～7.0 d, GY顯著提高51.5%～169.5% (<0.01), N240增產(chǎn)效應(yīng)最優(yōu); 增施氮肥導(dǎo)致PFPN和ANUE比N180/N120顯著降低11.7%～57.9%和2.5%～54.9%、19.9%～52.6%和4.9%～37.0%。與NH相比, DH處理DM和GW顯著提高0.8%～55.7%和3.4%～79.3%, 籽粒含水率(grain moisture content, GMC)顯著降低至22.0%～27.9%, GY、PFPN和ANUE顯著提高10.6%～18.5%、4.4%～26.8%和1.5%～48.6%。線性加平臺(tái)模型分析表明, DH處理比NH GY提高11.3%～12.6% (<0.01), 達(dá)12.0×103kg hm–2和7.0×103kg hm–2, 但最優(yōu)施氮量自200～210 kg hm–2增至247 kg hm–2。綜之, 華北平原熱量限制區(qū)夏玉米傳統(tǒng)收獲情景下減氮至200 kg hm–2, 產(chǎn)量穩(wěn)定在6.0×103～10.5×103kg hm–2以上; 延遲收獲情景下, 降低籽粒含水率, 減氮至240 kg hm–2, 產(chǎn)量達(dá)8.0×103～12.0×103kg hm–2以上, PFPN和ANUE最優(yōu)為19.2～49.6 kg kg–1和15.3～20.8 kg kg–1, 可為區(qū)域夏玉米降低籽粒含水率, 實(shí)現(xiàn)籽粒機(jī)收與減氮穩(wěn)產(chǎn)高效的生產(chǎn)目標(biāo)提供理論支撐。

夏玉米; 降雨年型; 施氮量; 收獲期; 產(chǎn)量; 氮肥利用效率

華北平原是我國夏玉米主產(chǎn)區(qū)之一, 在保障國家糧食安全中發(fā)揮重要作用[1], 但大部分地區(qū)周年熱量資源緊張, 兩熟制體系中受冬小麥播/收期雙重限制, 夏玉米成熟和脫水熱量資源緊張, 致使成熟期籽粒含水率較高[2], 難以達(dá)到適宜機(jī)械粒收含水量(28%或25%)的標(biāo)準(zhǔn)[3], 成為限制區(qū)域夏玉米機(jī)械粒收技術(shù)和全程機(jī)械化的瓶頸問題[4]?！半p晚技術(shù)”推遲夏玉米收獲可以在不增加成本前提下, 延長夏玉米灌漿脫水時(shí)間, 促進(jìn)生育后期物質(zhì)積累及向籽粒轉(zhuǎn)運(yùn)[5], 研究表明夏玉米生理成熟后田間站稈晾曬使百粒重自23.3～37.4 g提高至22.9～38.4 g[6], 夏玉米延長45 d脫水時(shí)間含水量降低至14.4%～17.3%, 周年增產(chǎn)6.7%～7.9%[7], 同時(shí)提高籽粒氮素積累量39.0%～57.3%, 實(shí)現(xiàn)氮素利用效率提高[8]。周寶元等[9]研究表明, 在華北平原中南部熱量資源相對(duì)豐沛區(qū)夏玉米延遲收獲后可以通過冬小麥增大播量提高基本苗數(shù)量彌補(bǔ)播期延遲群體數(shù)量不足的問題; 但在平原北部熱量資源緊張區(qū), 延遲夏玉米收獲難以播種冬小麥, 可將冬小麥變革為春小麥, 實(shí)現(xiàn)夏玉米粒收技術(shù)與周年產(chǎn)量及氣候資源協(xié)同提高。氮素在玉米器官建成、光合作用和產(chǎn)量形成中發(fā)揮關(guān)鍵作用[10]。研究表明, 施氮量增加, 調(diào)控干物質(zhì)積累和產(chǎn)量構(gòu)成因素[11], 促進(jìn)光合產(chǎn)物向籽粒的轉(zhuǎn)運(yùn), 提高籽粒灌漿速率和粒重[12], 實(shí)現(xiàn)增產(chǎn)。但華北平原高度集約化的冬小麥-夏玉米周年體系中大量施氮問題突出[13], 僅夏玉米季農(nóng)田氮肥投入量平均達(dá)276 kg hm–2, 但利用率低于25%[14], 且氨揮發(fā)損失較高[15], 導(dǎo)致肥料利用率低和環(huán)境生態(tài)等問題[16-17]。為破解過量施氮對(duì)環(huán)境生態(tài)的危害, 提高氮素利用效率, 適量減氮能協(xié)調(diào)氮素積累與轉(zhuǎn)運(yùn)[18], 促進(jìn)植株對(duì)氮素吸收和利用[19], 增加土壤硝態(tài)氮累積并減少N2O的排放[20], 優(yōu)化施氮使氮肥偏生產(chǎn)力從26 kg kg–1提升至57 kg kg–1 [21]。華北平原地處亞熱帶季風(fēng)氣候區(qū), 夏玉米生育期處于降雨季, 近年來極端降水如夏季大暴雨日數(shù)和平均日降水強(qiáng)度有增加趨勢(shì)[22], 2021年降雨量近1000 mm, 是平常年份的2倍以上, 顯著影響夏玉米生長發(fā)育與產(chǎn)量形成。強(qiáng)降雨導(dǎo)致夏玉米發(fā)生淹水脅迫, 玉米根系生理性危害加劇, 葉綠體結(jié)構(gòu)破壞, 光系統(tǒng)活性和光合速率顯著降低, 葉片失綠早衰, 干物質(zhì)積累急劇降低, 雌雄穗發(fā)育不良, 籽粒物質(zhì)轉(zhuǎn)運(yùn)量減少, 籽粒灌漿速率顯著降低, 灌漿時(shí)間縮短, 穗粒數(shù)減少和粒重降低導(dǎo)致減產(chǎn)甚至絕收, 脅迫時(shí)間越早, 淹水時(shí)間越長影響越顯著[23-27]。

如前所述, 優(yōu)化施氮調(diào)控夏玉米產(chǎn)量及氮素利用已有大量研究, 但為實(shí)現(xiàn)華北平原夏玉米延遲收獲降低籽粒含水量實(shí)現(xiàn)機(jī)械粒收情境下, 特別是針對(duì)2021年長時(shí)間強(qiáng)降雨情境下, 施氮量與收獲期對(duì)后期籽粒灌漿與脫水過程、產(chǎn)量形成與氮肥利用效率的影響未見報(bào)道。為此, 本論文針對(duì)華北平原北部熱量資源限制區(qū), 比較分析2020年和2021年2個(gè)代表性降雨年型下, 施氮量與收獲期調(diào)控夏玉米籽粒灌漿脫水過程與產(chǎn)量形成及氮肥利用的效應(yīng), 以期為華北平原延遲收獲夏玉米穩(wěn)產(chǎn)減氮增效與機(jī)械粒收技術(shù)發(fā)展提供理論支撐。

1 材料與方法

1.1 試驗(yàn)設(shè)計(jì)

于2020年和2021年6月至11月在天津市優(yōu)質(zhì)農(nóng)產(chǎn)品開發(fā)示范中心(39°42′N, 117°49′E)進(jìn)行, 0～20 cm土壤基礎(chǔ)養(yǎng)分含量為有機(jī)質(zhì)18.6 g kg–1、全氮1.09 g kg–1、水解性氮77.68 mg kg–1、速效磷64.8 mg kg–1、速效鉀296 mg kg–1。試驗(yàn)期間夏玉米生育氣象數(shù)據(jù)如圖1, 2020年夏玉米生長季降雨量為287.6 mm, 2021年降雨量為973.5 mm。據(jù)天津市1991—2020年統(tǒng)計(jì)年鑒年均降水量566.1 mm, 6月至10月平均降水量為451.6 mm, 將2020年認(rèn)定為干旱年型, 2021年為豐水年型。試驗(yàn)品種選用京農(nóng)科728, 采用二因素隨機(jī)區(qū)組試驗(yàn)設(shè)計(jì), 因素施氮量為0 kg hm–2(N0)、120 kg hm–2(N120, 2021)、180 kg hm–2(N180)、240 kg hm–2(N240)、300 kg hm–2(N300)、360 kg hm–2(N360)和450 kg hm–2(N450, 2020), 2021年施氮量根據(jù)2020年試驗(yàn)結(jié)果進(jìn)行優(yōu)化增加N120而去掉N450處理, 因素收獲期為正常收獲(normal harvest, NH, 10月5 (13)日)和延遲收獲(delayed harvest, DH, 11月8 (6)日)。種植密度75,000株 hm–2, 行距60 cm、株距22.2 cm, 小區(qū)長7.0 m, 寬4.2 m, 種植7行, 重復(fù)3次, 各小區(qū)間設(shè)置1 m隔離帶。N肥按照50%-30%-20%分別按種肥-拔節(jié)肥-大喇叭口期肥施用, P2O5120 kg hm–2和K2O 150 kg hm–2全部作種肥。及時(shí)防治病蟲草害, 2020年灌水2次, 2021年排水。

圖1 2020年和2021年玉米生育期氣象數(shù)據(jù)

1.2 測(cè)定指標(biāo)及方法

1.2.1 干物質(zhì)積累量(dry matter accumulation, DM) 于拔節(jié)期(V6)、吐絲期(R1)和收獲期, 每小區(qū)取代表性植株3株, 分為營養(yǎng)器官和籽粒(收獲期) 兩部分, 105℃殺青30 min, 85℃烘干至恒重后稱重。

1.2.2 籽粒灌漿與脫水動(dòng)態(tài) 每小區(qū)選取吐絲期一致植株50株掛牌標(biāo)記, 自吐絲開始每10 d取2個(gè)代表性果穗, 每穗取中部籽粒50粒, 測(cè)定籽粒鮮重, 105℃殺青30 min后85℃烘干至恒重, 稱干重(grain weight, GW, mggrain–1), 籽粒含水率(grain moisture content, GMC, %) = (鮮重?烘干重)/鮮重× 100%。以天數(shù)(d)為自變量, 粒重(GW)為因變量, 用Logistic方程GW =(1+e–cd))擬合籽粒增重過程并計(jì)算籽粒灌漿參數(shù)。用指數(shù)方程=e模擬籽粒含水率變化過程, 對(duì)方程求導(dǎo)得到=e模擬籽粒脫水速率(grain dehydration rate, GDR, % d–1)變化過程。

1.2.3 產(chǎn)量及其構(gòu)成因素 收獲期每小區(qū)連續(xù)收獲20穗, 帶回室內(nèi)立即考種, 數(shù)取穗行數(shù)(ear lines number, ELN)、行粒數(shù)(line grains number, LGN), 脫粒后稱取鮮千粒重和全部粒重, 用PM8188-A谷物水分儀測(cè)定含水率后按14%安全含水率計(jì)算千粒重(1000-grain weight)和產(chǎn)量(GY)。

1.2.4 氮肥利用效率 氮肥偏生產(chǎn)力(nitrogen partial factor productivity, PFPN, kg kg–1) = 籽粒產(chǎn)量/施氮量, 氮肥農(nóng)學(xué)效率(nitrogen agronomic use efficiency, ANUE, kg kg–1) = (施氮區(qū)玉米產(chǎn)量–不施氮區(qū)玉米產(chǎn)量)/施氮量。

2 結(jié)果與分析

2.1 干物質(zhì)積累量

由圖2可看出, 與干旱年型(2020)相比, 豐水年型(2021)夏玉米V6、R1和收獲期DM降低16.3%～64.6%、48.5%～76.8%和47.6%～81.5%, 達(dá)極顯著水平。與N0相比, 施氮處理在干旱年型下V6、R1、NH和DH的DM顯著提高50.3%～91.2%、25.1%～47.0%、61.2%～99.5%和14.3%～29.9%, 豐水年型下增幅分別達(dá)103.1%～272.5%、64.8%～203.1%、126.5%～248.8%和121.5%～239.9%, 差異達(dá)極顯著水平。干旱年型和豐水年型下, DH收獲期DM比NH顯著提高0.8%～55.7%和1.2%～3.8%, DH顯著提高干旱年型下籽粒干重, 但顯著降低了豐水年型干物質(zhì)向籽粒的轉(zhuǎn)運(yùn)分配。NH處理時(shí), 中高施氮水平收獲期DM比低氮水平(N180和N120)顯著提高10.8%～23.7%和12.4%～54.0%, 且以籽粒增加(6.0%～28.7%和36.4%～90.7%)為主; DH處理時(shí), 干旱年型施氮水平間DM無顯著差異, 豐水年型施氮水平間DM差異達(dá)顯著水平, N240-N360水平比N120-N180顯著提高13.8%～53.5%, 其中營養(yǎng)器官增重3.4%～35.7%, 籽粒增加22.1%～66.9%。

圖2 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米干物質(zhì)積累量的影響

Stem+Leaf: 莖+葉; Grain: 籽粒。NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。N0: 施氮量為0 kg hm–2; N120: 施氮量為120 kg hm–2; N180: 施氮量為180 kg hm–2; N240: 施氮量為240 kg hm–2; N300: 施氮量為300 kg hm–2; N360: 施氮量為360 kg hm–2; N450: 施氮量為450 kg hm–2。V6: 拔節(jié)期; R1: 吐絲期。不同小寫字母表示不同施氮處理在同一時(shí)期達(dá)到顯著差異(< 0.05)。

NH: the normal harvest treatment; DH: the delayed harvest treatment. N0: 0 kg hm–2; N120: 120 kg hm–2; N180: 180 kg hm–2; N240: 240 kg hm–2; N300: 300 kg hm–2; N360: 360 kg hm–2; N450: 450 kg hm–2. V6: the jointing stage; R1: the silking stage. The different lowercase letters indicated there were significantly different at< 0.05 among different N treatments in the same stage.

2.2 籽粒灌漿動(dòng)態(tài)

夏玉米粒重(GW)隨灌漿進(jìn)程呈S型曲線趨勢(shì)增長(圖3), 多雨導(dǎo)致GW顯著降低2.1%～28.1% (2021 vs 2020)。干旱年型下, 施氮后GW在NH和DH處理比N0顯著提高26.5%～35.7% (60.9～82.1 mg grain–1)和5.9%～14.8% (18.1～45.6 mg grain–1), 施氮量間無差異, 分別在N300和N360水平下GW最高; 豐水年型下, 與N0相比, 施氮處理GW在NH和DH時(shí)顯著提高12.0%～23.1% (29.1～56.0 mg grain–1)和6.4%～34.7% (14.6～79.0 mg grain–1), 分別在N240和N300處理GW最高。DH處理在NH處理同天GW無差異, 在干旱年型下DH處理推遲收獲25～33 d后GW比NH顯著提高9.4%～34.0%, 但豐水年型下DH處理GW比NH提高3.9%～8.7% (>0.05)。

分析夏玉米籽粒灌漿速率參數(shù)可看出(圖4), 與干旱年型相比, 2021年降雨增加使NH處理到達(dá)最大灌漿速率(maximum grain filling rate,max)時(shí)間(time reaching themax,max)推遲2.5 d, 但使DH處理max推遲3.5 d, 灌漿速率最大時(shí)生長量(weight increment ofmax,max)降低15.7%, 且灌漿持續(xù)期(active grain filling period,)縮短14.3 d。比較施氮量間籽粒灌漿參數(shù)可以看出, 干旱年型下, 與N180相比, NH處理在N300水平max提高10.7%、積累起始勢(shì)(initial grain filling power,0)降低12.6%、延長14.4%至46.3 d, DH處理在N360水平max、max提高15.8%和12.4%; 豐水年型下, 與N120相比, NH處理在N240水平max提高12.0%至11.8 mg (grain d)–1, DH處理在N240-N300水平max提高12.5%～12.9%、0降低26.2%～ 31.5%、延長35.5%～45.9%, 顯著高于其他施氮量。不同年型下收獲期處理對(duì)籽粒灌漿速率參數(shù)影響趨勢(shì)恰恰相反, 在干旱年型下與NH相比, DH處理max和0顯著降低1.9%～20.0%和11.6%～33.7%,max提高0.7%～22.8%,max和分別推遲1.1～6.6 d和延長5.5～18.7 d; 而豐水年型下, DH處理max和0比NH顯著提高1.7%～31.6%和5.6%～47.6%,max降低3.7%～11.1%,max與分別提早0.9～5.0 d和縮短1.9～13.4 d。

圖3 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米灌漿期籽粒干重的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. Treatments are the same as those given in Fig. 2.

圖4 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米籽粒灌漿速率的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. Treatments are the same as those given in Fig. 2.

2.3 籽粒含水率及脫水速率

隨籽粒灌漿進(jìn)程, 籽粒含水率(GMC)呈指數(shù)方程變化趨勢(shì)(圖5), 不同降水年型下, NH和DH處理收獲期GMC均在N240水平時(shí)最低, 分別為30.8%～32.4%和23.0%～23.2%; 干旱年型下, NH和DH處理其他施氮水平GMC比N240增加17.5%～ 24.5% (<0.05)和7.0%～13.2% (<0.05); 豐水年型下, NH和DH處理不同施氮水平間GMC均無顯著差異。多雨年型下同時(shí)期GMC顯著高于干旱年型, NH處理收獲期GMC分別為30.8%～41.8% (2020)和32.4%～41.4% (2021), 2021年NH處理收獲期比2020年推遲9 d, 但GMC降低不顯著; 年際間DH處理推遲25～33 d收獲GMC比DH顯著降低25.2%～ 39.1%和25.9%～40.5%, 達(dá)到22.0%～27.9%和23.2%～26.3%。

夏玉米籽粒脫水速率(GDR)隨灌漿進(jìn)程不斷降低(圖6), 豐水年型下同時(shí)期GDR低于干旱年型, 但差異不顯著; NH和DH處理收獲期豐水年型GDR比干旱年型顯著降低11.2%～91.0%和52.5%～80.4%。不同施氮水平間, GDR差異主要表現(xiàn)在灌漿前期(30 d), 在干旱年型下, N240 GDR比其他施氮水平提高6.5%～11.8%; 豐水年型下N360與N240間差異不顯著, 但比其他施氮量提高34.7%～75.4%。NH處理下, 脫水速率為(0.031～0.042) % d–1(2020)和(0.046～ 0.059) % d–1(2021), DH處理推遲25～33 d收獲GDR顯著降低至(0.0030～0.0062) % d–1(2020)和(0.0008～ 0.0025) % d–1(2021)。

2.4 產(chǎn)量及產(chǎn)量構(gòu)成因素

豐水年型夏玉米產(chǎn)量(GY)比干旱年型極顯著降低了31.4%～58.3% (圖7), 且降雨導(dǎo)致DH處理比NH的增產(chǎn)幅度顯著降低; 干旱年型下N240以上施氮水平DH產(chǎn)量比NH增產(chǎn)10.6%～18.5% (<0.05), 豐水年型下不同施氮水平DH處理比NH增產(chǎn)4.2%～14.7%, 但均未達(dá)顯著水平; 干旱和豐水年型下, 施氮量與收獲期對(duì)產(chǎn)量的互作效應(yīng)均未達(dá)顯著水平。與N0相比, 豐水年型下施氮后顯著增產(chǎn)74.4%～ 169.5%, 顯著高于干旱年型的增產(chǎn)效應(yīng)(51.5%～ 99.1%), 且均表現(xiàn)為同一施氮量對(duì)DH處理的增產(chǎn)效應(yīng)顯著高于NH處理。干旱年型下, 不同施氮水平間在NH處理時(shí)GY無顯著差異, N300最高為11.2×103kg hm–2, DH處理施氮量達(dá)N240水平即無顯著差異, 比N180增產(chǎn)11.8%～23.0% (<0.05); 豐水年型下, NH和DH處理GY在N240水平以上即無顯著差異, 分別比N120-N180顯著增產(chǎn)21.7%～ 50.2%和12.6%～54.5%。線性加平臺(tái)模型分析可知, 干旱和豐水年型下, DH比NH處理最高產(chǎn)量提高12.6%和11.3%, 干旱年型下DH和NH最高產(chǎn)量分別為12.00×103kg hm–2和10.66×103kg hm–2, 比豐水年型提高4.35×103～4.98×103kg hm–2, 但DH最優(yōu)施氮量比NH增加30.3～36.1 kg hm–2, 分別為247.2～248.6 kg hm–2和201.1～218.3 kg hm–2。

圖5 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米灌漿期籽粒含水率的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. Treatments are the same as those given in Fig. 2.

圖6 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米灌漿期籽粒脫水速率的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. Treatments are the same as those given in Fig. 2.

豐水年型下, 夏玉米穗行數(shù)(ELN)、行粒數(shù)(LGN)和穗粒數(shù)(EGN)比干旱年型顯著減少20.3%～21.0%、30.6%～31.5%和44.7%～47.4%, 千粒重(1000-GW)降低2.7%～3.0% (>0.05) (表1)。干旱年型下, N450水平EGN顯著少于其他施氮水平, 但在NH處理時(shí)1000-GW隨施氮量增加顯著增加, DH處理時(shí)1000-GW在N240水平以上即無差異; 豐水年型下, ELN和EGN在N240-N360水平下顯著多于N120, 而施氮水平間1000-GW無顯著差異。DH處理推遲25～33 d收獲對(duì)ELN、LGN和EGN無影響, 但1000- GW比NH處理顯著提高7.8%～17.3% (2020年)和6.4%～15.2% (2021年)。

2.5 氮肥利用效率

由圖8可知, 干旱年型下夏玉米氮肥偏生產(chǎn)力(PFPN)比豐水年型顯著提高42.8% (NH)和37.3% (DH)。夏玉米PFPN隨施氮量增加顯著降低, 干旱年型下, 增施氮肥在NH處理和DH處理時(shí)比N180分別降低16.6%～57.9%和11.7%～55.3%, 且施氮處理間差異均達(dá)顯著水平; 豐水年型下, NH處理在N120水平下最高(36.7 kg kg–1,<0.05), 且N360水平下最低(19.4 kg kg–1,<0.05), N240與N180和N300無差異, DH處理下N180處理PFPN顯著低于N120但顯著高于N240-N360, 在N240-N360水平間無差異。干旱年型下, DH處理在N240以上水平PFPN比NH顯著提高10.6%～15.6%, 豐水年型下, DH處理僅在N120-N180水平時(shí)比NH顯著提高19.6%和26.8%。

由圖9可知, 豐水年型下NH處理氮肥農(nóng)學(xué)利用效率(ANUE)比干旱年型顯著降低18.0%, 而DH處理ANUE降雨年型間無顯著差異。干旱年型下, NH和DH處理ANUE在N180-N300間無差異, 比N360和N450顯著提高17.7%～54.9%; 豐水年型下, NH和DH處理在N120-N300水平間無顯著差異, N360比N120顯著降低28.7%和37.0%。干旱年型下, DH處理ANUE在N180水平下比NH處理顯著降低12.4%, 但在N360水平下顯著提高12.5%, 其他水平間無差異; 豐水年型下, DH處理ANUE在N120-N180水平比NH顯著提高21.6%和48.6%。

3 討論

2021年華北平原強(qiáng)降雨導(dǎo)致夏玉米受到淹水脅迫, 淹水脅迫導(dǎo)致夏玉米產(chǎn)量降低[23], 不同時(shí)期淹水對(duì)產(chǎn)量影響不同, 三葉期、拔節(jié)期和花后淹水導(dǎo)致減產(chǎn)41.5%、26.5%和15.3%[24], 主要原因在于淹水限制根系發(fā)育[27], 導(dǎo)致玉米葉片葉綠素結(jié)構(gòu)破壞, 影響光合特性[23,26]及干物質(zhì)積累與轉(zhuǎn)運(yùn)[23], 吐絲后籽粒灌漿持續(xù)期縮短, 灌漿速率降低, 最大灌漿速率時(shí)間提前, 粒重顯著降低導(dǎo)致減產(chǎn)[25,28]。本研究表明, 在大田非可控條件下夏玉米全生育期尤其是生育前期的持續(xù)強(qiáng)降雨使其生長發(fā)育受到顯著抑制, 灌漿后期葉片早衰, 導(dǎo)致干物質(zhì)積累量顯著降低16.3%～81.5%, 同時(shí)影響光合產(chǎn)物向籽粒的轉(zhuǎn)運(yùn), 豐水年型下穗行數(shù)、行粒數(shù)和穗粒數(shù)比干旱年型顯著減少20.3%～21.0%、30.6%～31.5%和44.7%～ 47.4%。淹水脅迫導(dǎo)致夏玉米籽粒灌漿持續(xù)期顯著縮短5～8 d, 灌漿速率降低且達(dá)到最大灌漿速率時(shí)間提前3～5 d, 粒重顯著降低2.1%～28.1%, 最終夏玉米減產(chǎn)31.4%～58.3%, 且氮肥偏生產(chǎn)力顯著降低27.2%～ 30.0%, 氮肥農(nóng)學(xué)利用效率降低3.5%～18.0%。Xu等[29]研究結(jié)果也表明多雨年份導(dǎo)致春玉米物質(zhì)積累與分配失衡引起產(chǎn)量降低, 支持本研究結(jié)果; Wang等[30]研究表明豐水年使穗粒數(shù)增加19.0%, 粒重提高是影響高密度群體產(chǎn)量的重要因素[31], 主要原因是研究區(qū)域在西北干旱區(qū), 與本研究的華北平原有較大的生態(tài)差異。

圖7 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米產(chǎn)量的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。不同小寫字母表示不同施氮處理收獲期產(chǎn)量達(dá)到顯著差異(< 0.05)。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. The different lowercase letters indicated the GY were significantly different at< 0.05 among different N treatments. Treatments are the same as those given in Fig. 2.

表1 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米產(chǎn)量構(gòu)成因素的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。不同小寫字母表示不同施氮處理收獲期產(chǎn)量構(gòu)成因素達(dá)到顯著差異(< 0.05)。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. The different lowercase letters indicated the GY components were significantly different at< 0.05 among different N treatments. Treatments are the same as those given in Fig. 2.

圖8 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米氮肥偏生產(chǎn)力的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。不同小寫字母表示不同施氮處理氮肥偏生產(chǎn)力達(dá)到顯著差異(＜0.05)。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. The different lowercase letters indicated the PFPN were significantly different at< 0.05 among different N treatments. Treatments are the same as those given in Fig. 2.

圖9 不同降雨年型下延遲收獲及施氮量對(duì)夏玉米氮肥農(nóng)學(xué)利用效率的影響

NH: 傳統(tǒng)收獲處理; DH: 延遲收獲處理。不同小寫字母表示不同施氮處理氮肥農(nóng)學(xué)利用效率達(dá)到顯著差異(< 0.05)。處理同圖2。

NH: the normal harvest treatment; DH: the delayed harvest treatment. The different lowercase letters indicated the ANUE were significantly different at< 0.05 among different N treatments. Treatments are the same as those given in Fig. 2.

華北平原周年冬小麥-夏玉米生產(chǎn)中, 由于熱量資源緊張且受冬小麥播/收期雙重限制, 夏玉米脫水時(shí)間短, 難以達(dá)到適宜機(jī)械粒收含水量(28%或25%)標(biāo)準(zhǔn)[3], 適當(dāng)延遲收獲延長籽粒灌漿脫水期, 降低籽粒含水量及籽粒破碎率, 提高機(jī)械粒收質(zhì)量[32]。本研究結(jié)果表明, 華北平原北部夏玉米延遲23～33 d收獲籽粒含水率可降至22.0%～27.9%, 比傳統(tǒng)收獲降幅達(dá)25.2%～40.5%, 基本滿足玉米機(jī)械粒收含水率的標(biāo)準(zhǔn)。李璐璐等[6]研究表明, 黃淮海南部夏玉米生理成熟后延遲收獲16～52 d, 籽粒含水率自21.5%～33.1%降至12.9%～24.4%, 籽粒含水率顯著低于本研究結(jié)果,但降幅低于本研究結(jié)果。分析差異產(chǎn)生的可能原因?yàn)? (1) 本試驗(yàn)所在華北平原北部夏玉米延遲收獲的10月中下旬與11月上旬氣溫整體低于南部地區(qū), 限制了籽粒脫水速率[33]; (2) 由于豐水年份下, 空氣濕度較大, 影響籽粒脫水速率, 豐水年份籽粒含水率顯著高于干旱年份。另外, 脫水速率低于干旱年份也能證明這個(gè)猜測(cè)。最重要的是華北平原北部熱量限制下為實(shí)現(xiàn)冬小麥-夏玉米周年生產(chǎn), 夏玉米收獲及冬小麥播種時(shí)間不能晚于10月10日, 導(dǎo)致了夏玉米在傳統(tǒng)收獲時(shí)間籽粒剛剛甚至尚沒有達(dá)到生理成熟期, 含水率高達(dá)30.8%～ 41.8%, 所以延遲收獲可使籽粒含水率的降幅高于華北平原南部。本研究結(jié)果表明, 延遲收獲在干旱年型下通過顯著提高夏玉米粒重及干物質(zhì)積累量9.4%～34.0%和0.8%～55.7%,實(shí)現(xiàn)增產(chǎn)10.6%～18.5% (<0.05), 但豐水年型下由于延遲收獲對(duì)粒重和干物質(zhì)積累量影響未達(dá)顯著水平, 實(shí)現(xiàn)增產(chǎn)4.2%～14.7%, 但不顯著。在華北平原南部的研究也表明夏玉米生理成熟后延遲收獲百粒重自23.3～ 37.4 g提高至22.9～38.4 g[6], 籽粒容重提高可實(shí)現(xiàn)增產(chǎn)9.72%[8], 大跨度延遲夏玉米收獲期可實(shí)現(xiàn)冬小麥- 夏玉米周年增產(chǎn)6.7%～7.9%[7], 實(shí)現(xiàn)周年光溫及氮素的高效利用[5]。本研究條件下, 盡管延遲收獲階段日均溫度為11.8℃和10.1℃低于籽粒灌漿15℃要求, 但日均最高溫為18.9℃和16.7℃, 同時(shí)積溫量達(dá)到400.9 ℃ d和241.7 ℃ d, 因此分析延遲收獲提高粒重的原因一猜測(cè)可能是傳統(tǒng)收獲情境下夏玉米尚未達(dá)生理成熟, 滿足≥10℃可維持籽粒灌漿活性[34]; 原因二猜測(cè)可能是日均最高溫大于15℃滿足籽粒灌漿的溫度需求, 同時(shí)日均最低溫4.5～5.9℃顯著抑制干物質(zhì)轉(zhuǎn)移, 較高的晝夜溫差提高了籽粒干物質(zhì)積累能力; 年際間延遲收獲階段日均最高溫與積溫量差異導(dǎo)致2021年延遲收獲粒重顯著低于2020年也驗(yàn)證了這個(gè)猜測(cè), 另外Liu等[34]通過緯度試驗(yàn)也表明灌漿期日均最高溫和積溫量與粒重呈顯著正相關(guān)也可以驗(yàn)證本猜測(cè)。因此, 在華北平原北部夏玉米延遲收獲后期光照、溫度和空氣濕度等生態(tài)資源調(diào)控籽粒灌漿和脫水速率的效應(yīng)值得進(jìn)一步研究。

由于氮素在作物產(chǎn)量形成過程的重要作用[10], 生產(chǎn)中農(nóng)戶為追求產(chǎn)量常進(jìn)行過高施氮[13], 華北平原夏玉米農(nóng)田氮肥投入量平均為276 kg hm–2 [14], 引起肥料利用率低和環(huán)境生態(tài)問題[14-17], 優(yōu)化施氮能夠協(xié)調(diào)氮素積累和轉(zhuǎn)運(yùn), 促進(jìn)植株光合產(chǎn)物積累, 顯著提高地上部生物量實(shí)現(xiàn)增產(chǎn)[12,18,35-36]。本研究表明, 夏玉米施氮量達(dá)240 kg hm–2以上時(shí)在正常收獲和延遲收獲處理情況下干物質(zhì)積累量增加均不顯著,但可提高干物質(zhì)向籽粒的轉(zhuǎn)運(yùn), 而且表現(xiàn)為在豐水年型下施氮量對(duì)干物質(zhì)分配的影響效應(yīng)更加顯著。施氮量增加促進(jìn)光合產(chǎn)物向籽粒轉(zhuǎn)運(yùn)改善籽粒灌漿特性[12], 最大灌漿速率及其生長量顯著提高, 灌漿活躍期延長[37], 粒重提高且穗粒數(shù)增加[36], 實(shí)現(xiàn)增產(chǎn); 但隨施氮量增加玉米氮肥偏生產(chǎn)力和氮肥農(nóng)學(xué)利用效率顯著降低[38-39]。本研究結(jié)果表明, 施氮提高夏玉米籽粒灌漿速率, 且延長灌漿持續(xù)期, 正常收獲和延遲收獲條件下均在施氮量240 kg hm–2以上時(shí)處理間粒重?zé)o顯著差異, 且在240 kg hm–2水平時(shí)灌漿前期脫水速率高于其他施氮水平, 收獲時(shí)籽粒含水率顯著降低; 240～360 kg hm–2處理行粒數(shù)和穗粒數(shù)顯著高于低氮量處理, 施氮240 kg hm2時(shí)產(chǎn)量增加不顯著。通過模型分析表明, 傳統(tǒng)收獲優(yōu)化減氮至200～220 kg hm–2, 保證夏玉米穩(wěn)產(chǎn)6.0 × 103～ 10.5×103kg hm–2水平, 延遲收獲條件優(yōu)化施氮量在240 kg hm–2水平, 可實(shí)現(xiàn)高產(chǎn)8.0×103～12.0×103kg hm–2, 模型優(yōu)化施氮后夏玉米氮肥偏生產(chǎn)力和農(nóng)學(xué)利用效率可達(dá)49.6 kg kg–1和20.8 kg kg–1。在豐水年型下, 氮素利用效率低于干旱年型, 施氮量增產(chǎn)效應(yīng)顯著下降, 分析原因可能是多雨淹水脅迫下氮素淋溶比例升高, 氮損失加劇, 同時(shí)玉米根系活性下降, 氮素利用能力顯著降低[16,20,39]。本研究結(jié)果表明, 豐水年型下施氮量對(duì)干物質(zhì)積累、產(chǎn)量的調(diào)控效應(yīng)顯著高于干旱年型, 這與張?jiān)t等[31]在西北旱區(qū)豐水年份提高密度對(duì)春玉米的增產(chǎn)效應(yīng)相似, 說明豐水年型下玉米高產(chǎn)更應(yīng)該關(guān)注密度和氮肥的管理。

4 結(jié)論

華北平原北部由于熱量資源限制, 夏玉米傳統(tǒng)收獲時(shí)籽粒含水量高達(dá)30.8%～41.8%, 只能機(jī)械穗收難以機(jī)械粒收, 而通過延長夏玉米收獲時(shí)期23～33 d, 可以實(shí)現(xiàn)籽粒含水量降低至22.0%～27.9%, 基本滿足玉米機(jī)械粒收含水率的標(biāo)準(zhǔn)。豐水年型導(dǎo)致夏玉米穗粒數(shù)減少, 粒重和干物質(zhì)積累量均降低, 產(chǎn)量比干旱年型顯著降低31.4%～58.3%, 延遲收獲通過提高干物質(zhì)積累量及粒重實(shí)現(xiàn)增產(chǎn), 施氮提高最大灌漿速率及其生長量, 延長灌漿持續(xù)時(shí)間提高粒重而實(shí)現(xiàn)增產(chǎn)。綜之, 華北平原北部夏玉米傳統(tǒng)機(jī)械穗收情境下, 優(yōu)化減氮至200 kg hm–2, 產(chǎn)量穩(wěn)定在6.0×103～10.5×103kg hm–2; 延遲20～35 d可達(dá)機(jī)械粒收標(biāo)準(zhǔn), 優(yōu)化施氮240 kg hm–2, 產(chǎn)量達(dá)8.0×103～12.0×103kg hm–2, 氮肥偏生產(chǎn)力和農(nóng)學(xué)利用效率為19.2～49.6 kg kg–1和15.3～20.8 kg kg–1。在華北平原中南部熱量資源相對(duì)豐沛區(qū)夏玉米延遲收獲后可以通過冬小麥增大播量提高基本苗數(shù)量彌補(bǔ)播期延遲群體數(shù)量不足的問題[7]; 但在北部熱量資源緊張區(qū), 延遲夏玉米收獲難以播種冬小麥, 能否將冬小麥變革為春小麥, 實(shí)現(xiàn)夏玉米粒收技術(shù)與周年穩(wěn)產(chǎn)減氮提效及氣候資源協(xié)同提高值得深入研究。

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Effects of nitrogen application and harvest time on grain yield and nitrogen use efficiency of summer maize under different rainfall years

LIU Meng1, ZHANG Yao1, GE Jun-Zhu1,*, ZHOU Bao-Yuan2, WU Xi-Dong1, YANG Yong-An3, and HOU Hai-Peng4

1College of Agronomy and Resources and Environment, Tianjin Agricultural University, Tianjin 300384, China;2Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China;3Tianjin High-quality Agricultural Products Development Demonstration Center, Tianjin 301500, China;4.Tianjin Agricultural Development Service Center, Tianjin 300061, China

To investigate the effects of nitrogen application and harvest time on summer maize grain filling and dehydration, yield formation, and nitrogen use efficiency in thermal resource restricted area in the North China Plain, we adopted a two-factor randomized block area experiment design, one factor was nitrogen application rate per hectare [0 kg (N0), 120 kg (N120, 2021), 180 kg (N180), 240 kg (N240), 300 kg (N300), 360 kg (N360), and 450 kg (N450, 2020)], and another factor was harvest time [normal harvest (NH) and delayed harvest (DH)]. Dry matter accumulation (DM), grain filling and dehydration processes, grain yield (GY) and its components, nitrogen partial factor productivity (PFPN), and agronomic nitrogen utilization efficiency (ANUE) were investigated. Compared to the dry year (2020), DM, grain weight (GW), a%, respectively, resulting in GY, PFPN, and ANUE significantly reduced by 31.4%–58.3%, 27.2%–30.0%, and 2.9%–18.0%, respectively. Compared with N0, nitrogen application significantly enhanced DM, and GW were 14.6–82.1 mg grain–1higher than N0, while the maximum grain filling rate (max) and its weight increment (max) were enhanced by 0.2–3.4 mg (grain d)–1and 10.4–44.1 mg grain–1, meanwhile the time reachingmax(max) were earlier by 0.4–7.0 d. The GY of nitrogen application treatments were dramatically raised by 51.5%–169.5% than N0, and in the N240level it was the optimized nitrogen application. Compared with that of N180/N120,with the increase of nitrogen application rate, the PFPN and ANUE in two years were significantly reduced by 11.7%–57.9% and 2.5%–54.9%, 19.9%–52.6% and 4.9%–37.0%, respectively. Compared with NH treatment, the DM and GW of DH treatment were increased significantly by 0.8%–55.7% and 3.4%–79.3%, and dramatically reduced grain moisture content to 22.0%–27.9% at harvest stage. The GY, PFPN, and ANUE of DH treatment were remarkable higher than NH treatment by 10.6%–18.5%, 4.4%–26.8%, and 1.5%–48.6%, respectively. The linear plus platform model showed that the highest GY of DH treatment obtained to 12.0×103kg hm–2and 7.0×103kg hm–2, which were significantly higher than NH by 11.3%–12.6% , whereas the optimal nitrogen application rate were reached to 247 kg hm–2form 200–210 kg hm–2, increased by 13.9%–22.9%. In conclusion, in thermal resource restricted area in the North nd ear grains number (EGN) under rainy year (2021) were significant decreased by 16.3%–81.5%, 2.1%–28.1%, and 44.7%–47.4 China Plain, the nitrogen application rate could reduce to 200 kg hm–2and GY stabilized above 6.0×103–10.5×103kg hm–2under normal harvest time, meanwhile the nitrogen application rate could optimized to 240 kg hm–2and achieved higher GY above 8.0×103–12.0×103kg hm–2with higher PFPN and ANUE at 19.2–49.6 kg kg–1and 15.2–20.8 kg kg–1levels under delayed harvest. In conclusion, the results revealed that the theoretic support for reduced summer maize grain moisture content, achieving the production goal as grain machine harvesting, nitrogen reduction, high yield and high nitrogen use efficiency of summer maize in the North China Plain.

summer maize; rainfall year types; nitrogen application rate; harvest time; grain yield; nitrogen use efficiency

10.3724/SP.J.1006.2023.23014

本研究由國家自然科學(xué)基金項(xiàng)目(31701378)和國家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2017YFD0300410)資助。

This study was supported by the National Natural Science Foundation of China (31701378) and the National Key Research and Development Program of China (2017YFD0300410).

葛均筑, E-mail: gjz0121@126.com.

E-mail: m15222312583@126.com

2022-02-18;

2022-06-07;

2022-07-14.

URL: https://kns.cnki.net/kcms/detail/11.1809.S.20220713.1910.002.html

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).