張 鴻, 朱從樺, 李其勇, 李星月, 郭 展, 鄭家國, 李旭毅**

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灌溉方式和施氮量對直播稻氮素和水分利用的影響*

張 鴻1, 朱從樺1, 李其勇1, 李星月1, 郭 展1, 鄭家國2, 李旭毅2**

(1. 四川省農(nóng)業(yè)科學(xué)院植物保護(hù)研究所/農(nóng)業(yè)部西南作物有害生物綜合治理重點實驗室 成都 610066; 2. 四川省農(nóng)業(yè)科學(xué)院作物研究所 成都 610066)

為研究不同灌溉方式和施氮量對直播稻的光合生產(chǎn)、干物質(zhì)積累、氮素利用、水分利用和稻谷產(chǎn)量的影響, 采用裂區(qū)試驗設(shè)計, 主區(qū)因素為品種: ‘德香4103’和‘金農(nóng)絲苗’, 副區(qū)因素為3種灌溉方式: 淺水灌溉、輕干濕交替灌溉和重干濕交替灌溉, 副副區(qū)因素為4個施氮量: 0 kg(N)·hm-2、120 kg(N)·hm-2、180 kg(N)·hm-2、240 kg(N)·hm-2, 分析測定直播稻的干物質(zhì)積累量、氮素積累量和利用率、水分利用率和產(chǎn)量等指標(biāo)。結(jié)果表明: 灌溉方式和施氮量對直播稻氮素利用和產(chǎn)量形成的影響存在顯著的互作效應(yīng)。與淺水灌溉相比, 輕干濕交替灌溉處理下‘德香4103’和‘金農(nóng)絲苗’抽穗期劍葉凈光合速率、拔節(jié)—抽穗期干物質(zhì)積累量、結(jié)實期莖葉氮素轉(zhuǎn)運量、成熟期籽粒中氮素積累量、氮素農(nóng)藝效率和氮肥回收效率顯著增加; 抽穗期葉面積指數(shù)、拔節(jié)前干物質(zhì)積累量、成熟期莖葉氮素積累量顯著降低。施氮量對‘德香4103’和‘金農(nóng)絲苗’氮素積累量、氮素利用效率、產(chǎn)量的影響存在差異。淺水灌溉處理中, 與無氮相比, ‘德香4103’和‘金農(nóng)絲苗’施氮后產(chǎn)量分別提高31.79%~48.77%和29.72%~45.36%; 施氮量超過180 kg·hm-2后, ‘德香4103’的產(chǎn)量顯著下降, 而‘金農(nóng)絲苗’相應(yīng)指標(biāo)卻無顯著變化。輕干濕交替灌溉處理中, 與無氮相比, ‘德香4103’和‘金農(nóng)絲苗’施氮后產(chǎn)量分別提高32.58%~61.10%和36.49%~48.45%; 施氮量超過180 kg·hm-2后‘德香4103’的產(chǎn)量無顯著變化, 氮肥回收效率、氮素農(nóng)藝效率均顯著下降, ‘金農(nóng)絲苗’的產(chǎn)量和干物質(zhì)積累量無顯著變化, 成熟期氮素積累量顯著提高。重干濕交替灌溉處理中, 與無氮相比, ‘德香4103’和‘金農(nóng)絲苗’施氮后產(chǎn)量分別提高37.01%~42.88%和30.11%~42.63%; 施氮量超過180 kg·hm-2后, ‘德香4103’和‘金農(nóng)絲苗’的產(chǎn)量無顯著變化; 但‘德香4103’成熟期氮素積累量顯著增加, ‘金農(nóng)絲苗’氮素積累量卻無顯著增加, 兩個品種氮素農(nóng)藝效率均顯著降低。綜上所述, 輕干濕交替灌溉更適合于直播稻高產(chǎn)、節(jié)水、高效栽培, 其中‘德香4103’產(chǎn)量在輕干濕交替灌溉下施純氮240 kg·hm-2處理最高, ‘金農(nóng)絲苗’產(chǎn)量在輕干濕交替灌溉下施純氮180 kg·hm-2處理最高。

水稻; 直播; 灌溉方式; 施氮量; 干物質(zhì)積累; 氮素利用; 水分利用; 產(chǎn)量

干旱是影響水稻豐產(chǎn)性最為突出的因素之一, 水稻節(jié)水栽培技術(shù)和抗旱能力提升被廣大科研工作者所重視[1-5]。近年來, 干濕交替灌溉技術(shù)在中國和東南亞國家得到快速推廣和延伸[6]。適度的水分脅迫有利于提高土壤通氣性, 增加土壤細(xì)菌、放線菌活性和數(shù)量, 促進(jìn)水稻根系生長[7], 提高土壤中部分酶活性及水稻根系氧化力和滲透調(diào)節(jié)物質(zhì)含量[4], 促進(jìn)水稻對輕度水分脅迫產(chǎn)生適應(yīng)性變化, 同時提高葉片氣孔導(dǎo)度、蒸騰速率和凈光合速率[8], 提高水稻產(chǎn)量[9], 降低耗水量, 提高水分生產(chǎn)率, 改善稻米品質(zhì)[10]。以往對干濕交替灌溉技術(shù)方面的研究缺少水分精確化控制, 加之該技術(shù)在不同生態(tài)區(qū)的適應(yīng)程度也不盡一致, 所以使得其對產(chǎn)量的影響結(jié)果并未達(dá)成共識[1,3,11]。為此, 在本試驗區(qū)進(jìn)一步開展干濕交替灌溉過程中水分控制程度研究能夠為水稻節(jié)水穩(wěn)產(chǎn), 甚至增產(chǎn)提供理論依據(jù)。

氮是水稻正常生長發(fā)育過程中必不可少的元素, 不同的氮肥施用方式[12]、施用量[13]、氮素形態(tài)[14]等均會對氮肥利用產(chǎn)生不同影響。水、氮在作物生產(chǎn)中往往是相互制約、相互協(xié)同的, 水氮互作在移栽稻上研究較多, 主要集中于干物質(zhì)生產(chǎn)、稻米品質(zhì)[10]、生理性狀[15-16]、產(chǎn)量、氮代謝酶、氮、磷、鉀的吸收[17]等方面, 主要結(jié)論是: 水、氮肥對水稻產(chǎn)量、部分生理指標(biāo)、氮吸收利用、氮代謝酶、根系特征、干物質(zhì)量等有顯著的互作效應(yīng)[15,18-19]。近年來, 隨著栽培方式多樣化, 直播稻推廣逐年受到重視, 直播面積、直播比例在不同地區(qū)均有較大發(fā)展。直播水稻具有用工少、勞動強(qiáng)度低、成本低等優(yōu)點, 順應(yīng)了輕簡化栽培發(fā)展的需求, 且與移栽稻相比, 直播稻播期推遲, 營養(yǎng)生長期縮短, 在利用溫光資源表現(xiàn)出一些不同的生育特征[20]。因此, 加強(qiáng)對直播稻栽培研究顯得十分重要。從播期、施肥、水分、氮肥運籌等方面對直播稻的產(chǎn)量、氮素吸收、養(yǎng)分積累利用、品質(zhì)、光合特性、生理指標(biāo)等開展了一系列研究[20-23], 但直播稻生產(chǎn)中水、氮互作效應(yīng)鮮見報道。本研究重在探索水氮互作對直播稻光合物質(zhì)及干物質(zhì)生產(chǎn)積累、產(chǎn)量及其構(gòu)成因素的影響, 以及直播稻的氮素吸收利用特點, 以探索直播稻水肥調(diào)控機(jī)理, 明確最優(yōu)水氮管理模式, 為高效養(yǎng)分管理和發(fā)展節(jié)水豐產(chǎn)型直播稻生產(chǎn)提供理論基礎(chǔ)和實踐依據(jù)。

1 材料與方法

1.1 試驗設(shè)計

試驗于2013年在四川省德陽市綿竹市孝德鎮(zhèn)金星村進(jìn)行。試驗田塊為砂壤土, 排灌方便, 前茬為冬閑田。土壤有機(jī)質(zhì)為23.40 g·kg-1、速效氮61.01 mg·kg-1、速效磷10.41 mg·kg-1、速效鉀70.42 mg·kg-1、全氮1.70 g·kg-1、全磷0.82 g·kg-1、全鉀18.32 g·kg-1。

試驗采用3因素裂區(qū)試驗設(shè)計, 主區(qū)為品種, 副區(qū)為灌溉方式, 副副區(qū)為施氮量。2個供試品種: ‘德香4103’(超級稻, 全生育期150 d)和‘金農(nóng)絲苗’(超級稻, 全生育期142 d)。3種灌溉方式: 淺水灌溉(W1), 2葉一心至成熟期保持1~3 cm水層; 輕干濕交替灌溉(W2), 播種后第64 d開始, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時(用中國科學(xué)院南京土壤研究所生產(chǎn)的真空表式土壤負(fù)壓計測定土壤水勢), 再灌水2~3 cm, 如此循環(huán); 重干濕交替灌溉(W3), 播種后64 d起每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán)。4個施氮量: 0 kg(N)·hm-2(N0)、120 kg(N)·hm-2(N120)、180 kg(N)·hm-2(N180)、240 kg(N)·hm-2(N240)。

4月5日采用水直播, 播種時進(jìn)行人工劃行均勻播種(芽谷), 播種量折干種為22.5 kg·hm-2, 播種行距為30 cm。播后出苗前進(jìn)行化學(xué)除草, 3葉一心期進(jìn)行人工定苗, ‘德香4103’和‘金農(nóng)絲苗’定植密度分別為3.0×l05株·hm-2和4.5×l05株·hm-2。氮、磷、鉀肥為尿素、過磷酸鈣、氯化鉀。氮肥中基肥占30%, 斷奶肥(1葉一心)占20%, 分蘗肥(4葉一心)占20%, 穗肥(倒3葉)占30%。P2O5和K2O施用量分別為90 kg·hm-2和180 kg·hm-2, 其中磷肥全作基肥施用, 鉀肥分基肥和拔節(jié)肥兩次施用, 各占50%。小區(qū)面積5 m×3 m=15 m2, 3次重復(fù), 小區(qū)間作埂(40 cm寬)覆膜, 其余田間管理同當(dāng)?shù)卮竺娣e生產(chǎn)田塊。

1.2 測定項目與方法

1.2.1 水分利用率

記錄全生育期各小區(qū)的降雨量, 記錄每一次灌溉量和排水量, 計算水分利用率。

1.2.2 干物質(zhì)積累和植株葉面積指數(shù)(LAI)

于拔節(jié)期、抽穗期及成熟期, 按各小區(qū)平均莖蘗數(shù)各取代表性植株1行(長度為1 m), 去根后分為葉、莖鞘、穗, 于105 ℃殺青30 min, 75 ℃烘至恒重后稱重。其中, 在抽穗期用美國生產(chǎn)的CID-203葉面積儀測定葉面積, 并計算葉面積指數(shù)(LAI)。

1.2.3 植株氮積累量

利用1.2.2中的干物質(zhì)樣品, 粉碎后過60目篩, 采用H2SO4-H2O2消化, 采用半微量凱氏定氮法測定各部位含氮量, 計算植株氮積累量。

1.2.4 凈光合速率

于抽穗期, 選擇晴天上午9:00—11:30, 用美國生產(chǎn)的LI-6400便攜式光合儀, 測定劍葉光合速率(n), 人工控制條件: CO2濃度為400 μmol·mol-1, 溫度為30 ℃, 光照強(qiáng)度為1 000 μmol·m-2·s-1。每小區(qū)測定5片, 重復(fù)測定3次。

1.2.5 考種與計產(chǎn)

于成熟期每小區(qū)調(diào)查2行(每行長度為4 m)稻株穗數(shù), 計算單位面積穗數(shù); 并取接近于平均穗數(shù)的植株1行(長度為2 m), 考查穗數(shù)、實粒數(shù)、空殼數(shù)、結(jié)實率、千粒重等產(chǎn)量構(gòu)成因素。去邊行及雜株按實收面積計產(chǎn)。

1.2.6 參數(shù)計算

氮素收獲指數(shù)=成熟期單位面積植株籽粒氮素積累量/植株氮素總積累量 (1)

結(jié)實期莖鞘(葉)氮素表觀轉(zhuǎn)移量(kg)=抽穗期莖鞘(葉)氮積累量-成熟期莖鞘(葉)氮積累量 (2)

結(jié)實期氮素表觀轉(zhuǎn)移率(kg×kg-1)=莖鞘(葉)氮素表觀轉(zhuǎn)移量/抽穗期莖鞘(葉)氮積累量 (3)

結(jié)實期轉(zhuǎn)移的氮對籽粒的貢獻(xiàn)率(kg×kg-1)=結(jié)實期莖葉氮素表觀轉(zhuǎn)移總量/成熟期籽粒氮積累量 (4)

氮素干物質(zhì)生產(chǎn)效率(kg·kg-1)=單位面積干物質(zhì)量/單位面積植株氮積累量 (5)

氮素稻谷生產(chǎn)效率(kg·kg-1)=單位面積籽粒產(chǎn)量/單位面積植株氮積累量 (6)

氮肥農(nóng)藝效率(kg·kg-1)=(施氮肥區(qū)產(chǎn)量-不施氮肥區(qū)產(chǎn)量)/施氮量 (7)

氮肥吸收利用效率(%)=(施氮區(qū)植株總吸氮量-空白區(qū)植株總吸氮量)/施氮量×100% (8)

水分利用率(kg·kg-1)=籽粒產(chǎn)量/(降雨量+灌水量-排水量) (9)

1.3 數(shù)據(jù)分析

采用DPS 7.05軟件進(jìn)行試驗數(shù)據(jù)分析, 最小顯著差法LSD檢驗平均數(shù), Origin 2017作圖。

2 結(jié)果與分析

2.1 灌溉方式和施氮量對直播稻產(chǎn)量及其構(gòu)成的影響

表1可見, 直播條件下水稻品種間產(chǎn)量差異極顯著, 表現(xiàn)為常規(guī)稻品種‘金農(nóng)絲苗’顯著高于雜交稻品種‘德香4103’, 有效穗、群體穎花量及結(jié)實率等產(chǎn)量性狀的顯著提高是‘金農(nóng)絲苗’在直播條件下表現(xiàn)出明顯產(chǎn)量優(yōu)勢的關(guān)鍵。同時, 各水氮處理對不同品種產(chǎn)量的影響均達(dá)極顯著水平, 且互作效應(yīng)極顯著。其中, ‘德香4103’產(chǎn)量以W2N240處理最高, ‘金農(nóng)絲苗’產(chǎn)量以W2N180處理最高。灌溉方式僅對有效穗和結(jié)實率的影響極顯著, 表現(xiàn)為有效穗隨灌水量的減少而顯著降低, W3處理結(jié)實率顯著低于W1、W2處理。施氮量對各產(chǎn)量性狀的影響均達(dá)極顯著, 表明施氮量對直播稻每穗粒數(shù)、群體穎花量及千粒重的影響高于灌溉方式, 但其與品種對有效穗的影響存在顯著的互作效應(yīng), 品種和灌溉方式對每穗粒數(shù)的影響存在極顯著的互作效應(yīng)。

除有效穗隨施氮量的增加而顯著提高外, 對其余產(chǎn)量構(gòu)成因素的影響因品種、灌溉方式而異?！孪?103’在常規(guī)灌溉方式下隨施氮量的增加, 每穗粒數(shù)先增加后減少, 群體穎花量呈增加趨勢, 結(jié)實率降低, 千粒重?zé)o顯著變化; 在輕、重干濕交替灌溉方式下隨施氮量的增加, 每穗粒數(shù)和群體穎花量呈增加趨勢, 而結(jié)實率和千粒重則反之?！疝r(nóng)絲苗’在常規(guī)灌溉方式下隨施氮量的增加, 每穗粒數(shù)減少, 群體穎花量增加, 千粒重先增加后減少; 在輕干濕交替灌溉方式下, 每穗粒數(shù)先增加后減少, 千粒重降低, 群體穎花量增加; 在重干濕交替灌溉方式下, 每穗粒數(shù)先增加后減少, 群體穎花量增加, 千粒重?zé)o顯著變化。此外, W1和W2灌溉方式下施氮量對該品種的結(jié)實率影響不顯著。

2.2 灌溉方式和施氮量對直播稻抽穗期光合物質(zhì)生產(chǎn)的影響

灌溉方式和施氮水平均顯著影響直播稻抽穗期葉面積指數(shù)(圖1), 各品種LAI隨灌水量的降低而顯著減少, 隨施氮水平的提高而顯著增加。灌溉方式和施氮水平對直播稻品種抽穗期劍葉光合速率的影響因品種而異?！孪?103’表現(xiàn)為劍葉光合速率隨灌水量的降低先增后減, 隨施氮量的增加而提高; 而‘金農(nóng)絲苗’在兩種交替灌溉方式下增加施氮量均能顯著提高抽穗期劍葉光合速率(圖2)。這表明灌溉方式和施氮水平對兩個直播稻品種光合生產(chǎn)的影響存在差異。

2.3 灌溉方式和施氮量對直播稻干物質(zhì)積累的影響

從表2看, 灌溉方式和施氮量對直播稻干物質(zhì)積累的影響因品種的不同存在顯著差異。對‘德香4103’而言, 相比重干濕交替灌溉, 常規(guī)灌溉方式下有利于拔節(jié)前以及抽穗后干物質(zhì)積累量的增加, 從而提高最終生物產(chǎn)量, 但收獲指數(shù)顯著降低; 采用干濕交替灌溉后減少灌溉水量有利于提高拔節(jié)至抽穗期間的干物質(zhì)積累量, 但灌溉水量過少拔節(jié)前及抽穗后干物質(zhì)積累量會減少, 導(dǎo)致生物量降低。不同灌溉方式下適當(dāng)增施氮肥實現(xiàn)干物質(zhì)積累量提高的途徑并不一致, 表現(xiàn)為常規(guī)灌溉和重干濕交替灌溉方式下適當(dāng)增施氮肥(施氮量分別為180 kg·hm-2和240 kg·hm-2)有利于提高抽穗后干物質(zhì)積累量, 輕干濕交替灌溉方式下適當(dāng)增施氮肥(240 kg·hm-2)有利于提高拔節(jié)至抽穗、抽穗后干物質(zhì)積累量。對‘金農(nóng)絲苗’而言, 常規(guī)灌溉和輕干濕交替灌溉方式下最終生物產(chǎn)量顯著高于重干濕交替灌溉方式, 二者最終生物產(chǎn)量優(yōu)勢分別在于拔節(jié)前和拔節(jié)至抽穗期干物質(zhì)積累量的提高; 常規(guī)灌溉和輕干濕交替灌溉方式下適當(dāng)增施氮肥(施氮量分別為240 kg·hm-2和180 kg·hm-2)有利于增加拔節(jié)前及抽穗后干物質(zhì)積累量; 而重干濕交替灌溉方式下適當(dāng)增施氮肥(施氮量為240 kg·hm-2)有利于提高拔節(jié)前及抽穗后干物質(zhì)積累量, 最終生物產(chǎn)量和收獲指數(shù)提高。這表明直播稻灌溉方式改變后, 各生育階段干物質(zhì)積累對最終生物產(chǎn)量的貢獻(xiàn)存在差異。

表1 灌溉方式和施氮量對不同品種直播稻產(chǎn)量及產(chǎn)量構(gòu)成的影響

W1: 2葉一心至成熟期保持1~3 cm水層; W2: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán)。同列不同小寫字母表示同一品種不同灌溉方式和施氮量組合差異顯著(<0.05)。*和**分別表示在0.05和0.01水平上差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage. Different lowercase letters in the same column indicate significant differences at 0.05 level among different interaction combinations of irrigation managements and nitrogen rates of a variety. * and ** mean significant differences at 0.05 and 0.01 levels, respectively.

圖1 灌溉方式和施氮量對不同品種直播稻抽穗期葉面積指數(shù)的影響

W1: 2葉一心至成熟期保持1~3 cm的水層; W2: 播種后第64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán); N0: 不施用氮肥; 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。不同小寫字母表示同一灌溉方式下, 不同施氮量間差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage; N0: no nitrogen fertilizer; N120: N rate was 120 kg·hm-2; N180: N rate was 180 kg·hm-2; N240: N rate was 240 kg·hm-2. Different lowercase letters indicate significant differences at 0.05 level among different nitrogen rates under the same irrigation management.

圖2 灌溉方式和施氮量對不同品種直播稻抽穗期劍葉光合速率的影響

W1: 2葉一心至成熟期保持1~3 cm的水層; W2: 播種后第64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán); N0: 不施用氮肥; 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。不同小寫字母表示同一灌溉方式下, 不同施氮量間差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage; N0: no nitrogen fertilizer; N120: N rate was 120 kg·hm-2; N180: N rate was 180 kg·hm-2; N240: N rate was 240 kg·hm-2. Different lowercase letters indicate significant differences at 0.05 level among different nitrogen rates under the same irrigation management.

表2 灌溉方式和施氮量對不同品種直播稻干物質(zhì)積累的影響

W1: 2葉一心至成熟期保持1~3 cm水層; W2: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán)。同列不同小寫字母表示同一品種不同灌溉方式和施氮量組合差異顯著(<0.05)。*和**分別表示在0.05和0.01水平上差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage. Different lowercase letters in the same column indicate significant differences at 0.05 level among different interaction combinations of irrigation managements and nitrogen rates of a variety. * and ** mean significant differences at 0.05 and 0.01 levels, respectively.

2.4 灌溉方式和施氮量對直播稻氮素積累及轉(zhuǎn)運的影響

由表3可知, 不同灌水處理除對莖鞘轉(zhuǎn)運量無顯著影響外, 灌水和施氮處理對氮素積累、轉(zhuǎn)運均有顯著或極顯著影響, 且對抽穗期、成熟期氮素積累量、葉片轉(zhuǎn)運量、穗部氮增加量具有極顯著的互作效應(yīng)。兩品種抽穗期氮素積累量存在顯著差異, ‘金農(nóng)絲苗’顯著高于‘德香4103’, 且水氮處理對兩個品種氮素積累量影響趨勢存在差異。‘德香4103’抽穗期及成熟期氮素積累量分別隨灌水量減少先升高后降低和降低趨勢, 隨施肥量增加而顯著升高。‘金農(nóng)絲苗’抽穗期氮素積累量隨灌水量減少而呈下降趨勢, 其成熟期氮素積累量受灌水量影響與‘德香4103’成熟期氮素積累量變化趨勢相同?！疝r(nóng)絲苗’抽穗期及成熟期氮素積累量隨施氮量增加而提高, 與‘德香4103’表現(xiàn)一致。兩個直播稻收獲指數(shù)均隨灌水量減少而增大, 隨施肥量增加而減小。灌水處理對兩個直播稻的葉片、莖鞘氮素轉(zhuǎn)運量及穗部氮增加量影響一致, 均隨灌水量增加而呈先升后降的趨勢, 在輕干濕交替灌溉處理下, 3個指標(biāo)均達(dá)最大值, 說明適度水分脅迫促進(jìn)了氮素向穗部轉(zhuǎn)移。在輕干濕交替灌溉處理中, ‘德香4103’在N180處理下葉片、莖鞘氮素轉(zhuǎn)運量及在N240穗部氮增加量均顯著高于其余施氮處理, 而‘金農(nóng)絲苗’則在N240處理下顯著高于其余施氮處理, 說明對氮素轉(zhuǎn)運、利用存在品種差異。兩個直播稻的葉片轉(zhuǎn)運率、莖鞘轉(zhuǎn)運率、氮轉(zhuǎn)運貢獻(xiàn)率在各個水氮處理下表現(xiàn)相同, 均隨灌水量減少而提高, 隨施氮量增加而降低。

從圖3可知, 成熟期不同部位的氮素積累量存在差異?！孪?103’莖鞘、葉片氮素積累量隨灌水量減少而減少(N240處理除外), 隨施氮量增加而增加; 籽粒氮素積累量隨灌水量減少而呈先上升后下降的趨勢, 在輕干濕交替灌溉下, N120、N180、N240均高于其余兩個灌水處理?！疝r(nóng)絲苗’莖鞘氮素積累量隨灌水量減少先上升后下降, 隨施氮量增加而增加, 在輕干濕交替灌溉下, N120、N180、N240處理高于其他兩個灌水處理; 葉片氮素積累量隨灌水量減少而減少, 隨施氮量增加而增加; 籽粒氮素積累量隨灌水量減少而先上升后下降, 隨施氮量增加而增加, 在輕干濕交替灌溉下, N120、N180處理氮素積累高于其他處理。說明輕干濕交替灌溉增加了成熟期穗部氮素積累量。

圖3 灌溉方式和施氮量對成熟期莖、葉、籽粒氮素積累的影響

W1: 2葉一心至成熟期保持1~3 cm的水層; W2: 播種后第64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán); N0: 不施用氮肥; 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。不同小寫字母表示同一灌溉方式下, 不同施氮量間差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage; N0:no nitrogen fertilizer; N120: N rate was 120 kg·hm-2; N180: N rate was 180 kg·hm-2; N240: N rate was 240 kg·hm-2. Different lowercase letters indicate significant differences at 0.05 level among different nitrogen rates under the same irrigation management.

2.5 灌溉方式和施氮量對直播稻氮素利用和水分利用率的影響

從表4可知, 不同灌水和氮肥處理對水稻氮素干物質(zhì)生產(chǎn)效率、氮素稻谷生產(chǎn)效率、氮素農(nóng)藝效率、氮肥回收效率、水分利用率影響均達(dá)顯著水平, 且互作效應(yīng)顯著?！孪?103’氮素生產(chǎn)效率隨灌水量減少而先上升后下降, 隨施氮量增加而降低; ‘金農(nóng)絲苗’氮素生產(chǎn)效率隨灌水量減少而增加, 在不同灌溉處理下, 其氮素生產(chǎn)效率均隨施氮量增加而降低。說明不同品種氮素生產(chǎn)效率存在差異。兩個直播稻氮素農(nóng)藝效率及氮肥回收效率均隨灌水量增加而呈先上升后下降趨勢, 不同施氮處理對其影響存在差異; 各灌水處理下, 高施氮處理降低了氮素農(nóng)藝效率及氮肥回收效率。中低施氮水平下, 相比淹灌, 輕干濕交替處理提高了‘德香4103’的氮素農(nóng)藝效率及氮肥回收效率; 在重干濕交替處理下兩個品種氮素農(nóng)藝效率及氮肥回收效率均隨施氮量增加而降低, 表明在各個灌水處理下, 高施氮量反而降低了氮素農(nóng)藝效率及氮肥回收效率?！孪?103’和‘金農(nóng)絲苗’的水分利用率隨著灌水量的增加而降低, 隨著施氮量的增加而增加。此外, 在輕干濕交替處理下, ‘德香4103’在N180處理下、‘金農(nóng)絲苗’在N120處理下氮肥回收效率均顯著高于其他處理。

3 討論

根系是植株吸收水分及養(yǎng)分的重要器官。有研究表明, 控制灌溉可不同程度提高水稻根系活力、最長根長、根直徑、根體積[24], 提高稻基農(nóng)田土壤酶活性、微生物量碳氮[25], 改善水稻根際土壤環(huán)境, 加快水稻根系泌氧, 促進(jìn)根系生長[26], 同時還提高氮代謝酶活性[27], 促進(jìn)對氮素吸收、轉(zhuǎn)運、利用。本研究表明, 輕干濕交替灌溉處理促進(jìn)了直播稻氮素吸收、積累, 同時促進(jìn)了葉片、莖鞘氮素轉(zhuǎn)運量, 但葉片轉(zhuǎn)運率、莖鞘轉(zhuǎn)運率、氮素轉(zhuǎn)運貢獻(xiàn)率不及重干濕交替灌溉處理?？梢钥闯? 直播稻受水分脅迫越重時, 氮素吸收越受影響, 穗部氮素則主要靠葉片、莖鞘部等營養(yǎng)器官向穗部轉(zhuǎn)運來保證, 這與王紹華等[18]研究結(jié)果一致。從施氮量來看, 氮肥用量較低時, 直播稻氮素積累量少, 但其葉片、莖鞘轉(zhuǎn)運率更高, 氮轉(zhuǎn)運貢獻(xiàn)率亦更高。水、氮兩因素對氮素積累及轉(zhuǎn)運過程中受施氮量影響比灌水處理更大。輕干濕交替灌溉處理能提高氮素農(nóng)藝效率及氮肥回收效率, 但氮素生產(chǎn)效率因品種影響存在差異, 水分脅迫降低了‘德香4103’氮素生產(chǎn)效率, 而提高了‘金農(nóng)絲苗’氮素生產(chǎn)效率。施氮量越高反而降低了氮素生產(chǎn)效率, 可能是高施氮量雖然增加了氮素積累, 但莖、葉氮素向穗部轉(zhuǎn)運降低, 在營養(yǎng)器官中滯留較多, 產(chǎn)生了較大的浪費[18]。輕干濕交替灌溉處理下, 適度提高氮肥用量可以提高氮素農(nóng)藝效率及回收效率, 但差異不明顯, 過高則會降低氮素生產(chǎn)效率, 且重干濕交替灌溉下, 施氮量增加降低了氮素利用效率。

有研究表明, 干濕交替灌溉有利于提高水稻劍葉光合速率, 且在抽穗期提高氮肥用量(180~270 kg·hm-2)可增加劍葉光合速率[28]。本研究結(jié)果與此一致, 輕干濕交替灌溉提高了抽穗期劍葉光合速率, 且其隨施氮量增加而呈上升趨勢。同時, 灌水量減少顯著降低了LAI, 但施氮水平提高可顯著增加LAI。施氮對產(chǎn)量及其構(gòu)成因素均有極顯著影響, 灌水對有效穗、結(jié)實率及產(chǎn)量有極顯著影響, 施氮量影響大于灌水。水氮互作效應(yīng)對直播稻產(chǎn)量、結(jié)實率影響顯著。孫永健等[15]指出水氮互作對穗粒數(shù)、產(chǎn)量有顯著影響, 而在本研究結(jié)果中, 水氮互作對結(jié)實率及產(chǎn)量產(chǎn)生了顯著影響, 可能是不同品種在不同環(huán)境下對水氮互作響應(yīng)存在差異。說明在本研究中水氮互作下產(chǎn)量的提高來源是結(jié)實率的顯著提升。付景等[11]研究表明, 輕干濕交替灌溉處理可以提高抗氧化酶活性, 提高超級稻根系中細(xì)胞分裂素(Z+ZR)和吲哚-3-乙酸(IAA)含量, 在生理基礎(chǔ)上對不利環(huán)境做出響應(yīng), 最終提高結(jié)實率, 促進(jìn)產(chǎn)量提高。在輕干濕交替灌溉處理下, 結(jié)實率、產(chǎn)量均高于其余兩個灌水處理, 適度水分脅迫促進(jìn)了直播稻產(chǎn)量提高, 但在施氮水平上產(chǎn)量高峰出現(xiàn)存在品種差異, 在此處理下, ‘德香4103’在N240、‘金農(nóng)絲苗’在N180下達(dá)最高產(chǎn)量。在輕度水分脅迫下, 適當(dāng)增加施氮量可以提高產(chǎn)量, 達(dá)到“以肥調(diào)水”的目的, 但不同品種對氮肥耐性有差異。因此, 針對不同品種的耐肥力, 可采用輕干濕交替灌溉并依據(jù)品種特性合理施用氮肥, 施用量在180~270 kg·hm-2之間, 提高氮素農(nóng)藝效率及回收效率, 可達(dá)到高產(chǎn)高效。

表4 灌溉方式和施氮量對不同品種直播稻氮素利用、水分利用率的影響

W1: 2葉一心至成熟期保持1~3 cm水層; W2: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-15 kPa時, 再灌水2~3 cm, 如此循環(huán); W3: 播種后64 d至成熟期, 每次灌水2~3 cm, 當(dāng)土壤水勢(soil)為-30 kPa時, 再灌水2~3 cm, 如此循環(huán)。同列不同小寫字母表示同一品種不同灌溉方式和施氮量組合差異顯著(<0.05)。*和**分別表示在0.05和0.01水平上差異顯著。W1: soil surface water layer was kept at 1-3 cm from 2.1 leaves to maturity; W2: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-15 kPa from 64 days after sowing to mature stage; W3: soil surface water layer was added to 2-3 cm when the soil water potential (soil) reached-30 kPa from 64 days after sowing to mature stage. Different lowercases letters in the same column indicate significant differences at 0.05 level among different interaction combinations of irrigation managements and nitrogen rates of a variety. * and ** mean significant difference at 0.05 and 0.01 levels, respectively.

4 結(jié)論

灌溉方式和施氮量對直播稻氮肥利用效率及產(chǎn)量形成存在顯著互作效應(yīng), 合理安排灌溉方式和施氮量可以實現(xiàn)直播稻產(chǎn)量、氮肥利用效率和水分利用率同步提高。從節(jié)水增產(chǎn)的角度, 輕干濕交替灌溉更適合于直播稻高產(chǎn)、節(jié)水、高效栽培, 且‘德香4103’配合施純氮240 kg·hm-2處理產(chǎn)量、氮素利用率和水分利用率最高, ‘金農(nóng)絲苗’配合施純氮180 kg·hm-2處理產(chǎn)量、氮素利用率和水分利用率最高。

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Effect of irrigation management and nitrogen rate on nitrogen and water utilization of direct-seeded rice*

ZHANG Hong1, ZHU Conghua1, LI Qiyong1, LI Xingyue1, GUO Zhan1, ZHENG Jiaguo2, LI Xuyi2**

(1. Institute of Plant Protection, Sichuan Academy of Agricultural Sciences / Key Laboratory of Integrated Pest Management on Crops in Southwest, Ministry of Agriculture, Chengdu 610066, China; 2. Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China)

Direct-seeded rice has advantages of less labor, lower labor strength and cost. But it meantime has different development characteristics from the transplanted rice. It is necessary to investigate the cultivation and growth of direct-seeded rice. In this study, a field experiment was conducted to investigate the effects of irrigation managements and nitrogen application rates on nitrogen and water utilization and yield of direct-seeded rice. In the experiment, a split-split plot design was set with rice varieties (‘Dexiang 4103’ and ‘Jinnongsimiao’) as the main factor, irrigation managements (shallow water irrigation, alternate irrigation with wetting and moderate drying, alternate irrigation with wetting and severe drying) as the sub-plot factor, and N rate (0 kg·hm-2, 120 kg·hm-2, 180 kg·hm-2and 240 kg·hm-2) as the split-split plot factor. The photosynthetic rate, dry matter accumulation, nitrogen utilization, water utilization and yield of direct-seeded rice were measured at different growth stages. There was a significant interaction between irrigation management and N rate on nitrogen utilization, water utilization and yield of direct-seeded rice. Compared with the shallow water irrigation, the net photosynthetic rate at jointing stage, dry matter accumulation at jointing-heading stage, nitrogen transport amounts of stems and leaves at mature stage, nitrogen accumulation of grains at maturity stage, nitrogen agronomic efficiency and nitrogen fertilizer recovery efficiency were significantly increased in the alternate irrigation with wetting and moderate drying; however, the leaf area index at heading stage, dry matter accumulation before jointing and nitrogen accumulation in stems and leaves at mature stage were significantly decreased. The effect of N rates on nitrogen accumulation, nitrogen utilization efficiency and yield of ‘Dexiang 4103’ and ‘Jinnongsimiao’ were different. Under the shallow water irrigation, compared with nitrogen free treatment, the yields of ‘Dexiang 4103’ and ‘Jinnongsimiao’ increased by 31.79%-48.77%, 29.72%-45.36%, respectively, under treatments of applying nitrogen fertilizer. But with the N rate increase (higher than 180 kg·hm-2), the yield of ‘Dexiang 4103’ was significantly decreased, and the corresponding indicators of ‘Jinnongsimiao’ were not significantly changed. Under the alternate irrigation with wetting and moderate drying, compared with nitrogen free treatment, the yields of ‘Dexiang 4103’ and ‘Jinnongsimiao’ increased by 32.58%-61.10%, 36.49%-48.45%, respectively, under treatments of applying nitrogen fertilizer. When N rate was more than 180 kg·hm-2, for ‘Dexiang 4103’, the yield was not significantly changed, nitrogen fertilizer recovery efficiency, the nitrogen agronomic efficiency decreased with the increase of N rate. For ‘Jinnongsimiao’, the yield, dry matter accumulation not changed significantly, and the nitrogen accumulation at maturity stages increased significantly. Under the alternate irrigation with wetting and severe drying, compared with nitrogen free treatment, the yields of ‘Dexiang 4103’ and ‘Jinnongsimiao’ increased by 37.01%-42.88%, 30.11%-42.63%, respectively, under the treatments of applying nitrogen fertilizer. When N rate was more than 180 kg·hm-2, the yield of two cultivars was not changed significantly, their nitrogen agronomic efficiency decreased with the N rate increaseing. The nitrogen accumulation of ‘Dexiang 4103’ at maturity stage increased significantly and that of ‘Jinnongsimiao’ was not changed significantly with N rate increasing. In summary, alternate irrigation with wetting and moderate drying was more suitable for high yield, water saving and high efficiency cultivation of direct-seeded rice. Furthermore, the highest yields of ‘Dexiang 4103’ and ‘Jinnongsimiao’ were observed under N rates of 240 kg·hm-2and 180 kg·hm-2, respectively.

Rice; Direct seeding; Irrigation management; Nitrogen rate; Dry matter accumulation; Nitrogen utilization; Water utilization; Yield

, E-mail: lixuyi_2005@sohu.com

Apr. 18, 2017;

Jun. 30, 2017

10.13930/j.cnki.cjea.170334

S511

A

1671-3990(2017)12-1802-13

李旭毅, 主要從事水稻栽培生理研究。E-mail: lixuyi_2005@sohu.com

張鴻, 主要從事高效栽培和農(nóng)產(chǎn)品綠色生產(chǎn)研究。E-mail: zhh503@163.com

2017-04-18

2017-06-30

* This study was supported by the National Key Research and Development Program of China (SQ2017YFNC050029), Sichuan Province Financial Innovation Ability Promotion Special Fund (2016GYSH-008, 2016GYSH-013) and Sichuan Science and Technology Support Program (2014NZ0008).

* 國家重點研發(fā)計劃項目(SQ2017YFNC050029)、四川省財政創(chuàng)新能力提升工程專項資金項目(2016GYSH-008, 2016GYSH-013)和四川省科技支撐計劃項目(2014NZ0008)資助