薛欣欣， 李嵐?jié)?魯劍巍， 李小坤， 任 濤， 叢日環(huán)， 周 鸝

(華中農(nóng)業(yè)大學資源與環(huán)境學院, 農(nóng)業(yè)部長江中下游耕地保育重點實驗室, 武漢 430070)

利用功能葉片鉀含量作為水稻鉀營養(yǎng)診斷指標的可行性研究

薛欣欣， 李嵐?jié)?魯劍巍*， 李小坤， 任 濤， 叢日環(huán)， 周 鸝

(華中農(nóng)業(yè)大學資源與環(huán)境學院, 農(nóng)業(yè)部長江中下游耕地保育重點實驗室, 武漢 430070)

水稻; 功能葉; 鉀素營養(yǎng); 診斷指標

作物化學分析診斷是一種傳統(tǒng)且最為常用的營養(yǎng)診斷方法，與土壤診斷、無損診斷等方法相比，能夠更直觀、精確地反映作物營養(yǎng)狀況，并且在較長一段時間內(nèi)仍將是作物營養(yǎng)診斷的主要手段[1-2]。有學者指出作物出現(xiàn)缺乏癥狀時的養(yǎng)分含量較穩(wěn)定，受養(yǎng)分來源的影響較小，因此作物化學分析診斷具有普遍意義[3]。

本研究在前人成果的基礎上，選擇了水稻主莖從上往下的第二功能葉作為全生育期鉀素營養(yǎng)的診斷部位。一方面考慮到該葉位的葉片樣品采集方便，對水稻植株損傷較?。涣硪环矫鎰t考慮到該葉位的葉片以全展開葉的狀態(tài)存在于整個生育期。本研究在田間試驗的基礎上，探討利用水稻功能葉片作為水稻鉀素營養(yǎng)診斷指標的可行性，旨在為水稻鉀肥的合理施用提供科學依據(jù)。

1 材料與方法

1.1 試驗設計

田間試驗于2012年5月至9月在湖北省蘄春縣向橋鄉(xiāng)進行。供試水稻品種為兩優(yōu)6326，土壤為花崗片麻巖母質發(fā)育的砂壤性水稻土。土壤基礎理化性狀： pH 5.0，有機質含量36.1 g/kg，全氮2.0 g/kg，速效磷2.1 mg/kg，速效鉀36.0 mg/kg，緩效鉀114.2 mg/kg。試驗設K2O 0、60、120、180、240、300和360 kg/hm27個鉀肥處理，分別用K0、K60、K120、K180、K240、K300和K360表示。為避免生育期間追施鉀肥對水稻植株鉀含量變化曲線的影響，因此鉀肥作基肥一次性施入；氮肥按N 180 kg/hm2分3次施用，分別為基肥50%、分蘗肥25%和穗肥25%；磷肥按P2O590 kg/hm2作基肥一次性施入。水稻種植采用大田育秧、移栽的方式，秧田肥料用量按N 57 kg/hm2，P2O526 kg/hm2和K2O 30 kg/hm2施用；移栽密度為25.5×104/hm2，單株/穴，秧苗生長良好。試驗采用隨機區(qū)組排列，小區(qū)面積4 m×7.5 m，3次重復。其他栽培管理措施同常規(guī)大田。

1.2 樣品采集及分析

第二功能葉的采集 于水稻分蘗初期(移栽后10 d)、分蘗盛期(移栽后20 d)、有效分蘗臨界期(移栽后31天)、拔節(jié)期(移栽后44 d)、孕穗期(移栽后58 d)、齊穗期(移栽后68 d)分別在各小區(qū)采集代表性植株6株，將主莖從上到下的第二功能葉進行收集，105℃殺青30min，70℃烘干至恒重，記錄各時期的干重，磨碎、過篩后測鉀。成熟期取未采樣的1/2小區(qū)進行測產(chǎn)，單打單收記錄各小區(qū)稻谷產(chǎn)量。

植物樣品鉀含量用1 mol/L的HCl振蕩浸提2 h，過濾、稀釋、火焰光度計測定[19]。

1.3 相關計算公式及方法

1)二次加平臺(quadratic plus plateau)鉀肥肥效模型[20]：

y=a+bx+cx2(x

y=p(x≥m)

式中：y為稻谷產(chǎn)量(kg/hm2)，x為鉀肥用量(K2O kg/hm2)，a為截距，b為直線回歸系數(shù)，c為二次回歸系數(shù)，m為二次型曲線與平臺的交點，p為平臺產(chǎn)量(kg/hm2)。

2)鉀含量診斷指標的建立方法(圖1)： 首先擬合施鉀量和稻谷產(chǎn)量的肥效方程，按最佳產(chǎn)量的100%、95%、90%、85%等進行分級；擬合第二功能葉鉀含量與產(chǎn)量的回歸方程；將各級臨界產(chǎn)量值代入回歸方程中求出對應的第二功能葉鉀含量臨界值，最終建立鉀素營養(yǎng)診斷指標。

圖1 功能葉鉀含量診斷指標建立方法Fig.1 Method of establishing the diagnosis index of the functional leaf potassium content

1.4 數(shù)據(jù)處理

數(shù)據(jù)分析和繪圖運用Microsoft Excel、Origin 8.0、SPSS 17.0和SAS統(tǒng)計軟件進行。

2 結果與分析

2.1 鉀肥用量對稻谷產(chǎn)量的影響

圖2 鉀肥用量對水稻產(chǎn)量的影響及鉀肥肥效模型Fig.2 Effect of potassium application rates on the grain yield and the potassium fertilizer efficiency model[注(Note)： 圖中不同字母表示施肥處理間差異達到5%顯著水平 Different letters indicate significant at 5% level between treatments.]

2.2 鉀肥用量對第二功能葉鉀含量的影響

圖3 水稻第二功能葉鉀含量的變化特征Fig.3 Temporal variations of the K contents of the 2nd functional leaves of rice at different growth stages under different K application rates[注(Note)： IT—分蘗初期Initiation of the tillering stage; AT—分蘗盛期Active tillering stage; ET—有效分蘗臨界期Effective tillering critical stage; J—拔節(jié)期Jointing stage; B—孕穗期Booting stage; F—齊穗期Full heading stage.]

2.3 第二功能葉鉀含量與稻谷產(chǎn)量和鉀肥用量的相關性分析

第二功能葉鉀含量與稻谷產(chǎn)量和鉀肥用量相關分析結果(表1)表明，第二功能葉鉀含量與稻谷產(chǎn)量的關系適合用對數(shù)方程擬合，各時期的相關系數(shù)均達極顯著水平(P<0.01)；鉀肥用量和第二功能葉鉀含量的關系則適合用一元二次方程擬合，除分蘗盛期顯著相關外(P<0.05)，其余各時期均達極顯著相關(P<0.01)。由此可以看出，第二功能葉鉀含量可以準確地預測稻谷產(chǎn)量水平和反映鉀肥施用水平，適合作水稻鉀營養(yǎng)的診斷部位。

表1 第二功能葉鉀含量與稻谷產(chǎn)量和鉀肥用量的相關系數(shù)(R2)

注(Note): * 和** 分別表示相關系數(shù)達5%和1%顯著水平 Indicate the correlation coefficients are significant at the 5% and 1% levels, respectively. DAT—Days after the transplanting.

圖4 第二功能葉鉀含量和稻谷產(chǎn)量的關系Fig.4 Relationship between the potassium contents of the 2nd functional leaves and the grain yields of rice at different stages[注(Note)： IT—分蘗初期Initiation of the tillering stage; AT—分蘗盛期Active tillering stage; ET—有效分蘗臨界期Effective tillering critical stage; J—拔節(jié)期Jointing stage; B—孕穗期Booting stage; F—齊穗期Full heading stage. * 和** 分別表示相關系數(shù)達5%和1%顯著水平Indicate the correlation coefficients are significant at the 5% and 1% levels, respectively. DAT—Days after the transplanting.]

生育時期Growthstage移栽后天數(shù)DAT(d)最佳產(chǎn)量相對值(%)Relativevalueofoptimumyield<858590909595100≥100分蘗初期Initiationofthetilleringstage10<0．980．981．151．151．341．341．57≥1．57分蘗盛期Activetilleringstage20<1．071．071．301．301．581．581．92≥1．92有效分蘗臨界期Effectivetilleringcriticalstage31<1．231．231．561．561．981．982．51≥2．51拔節(jié)期Jointingstage41<1．441．441．731．732．092．092．52≥2．52孕穗期Bootingstage58<0．970．971．141．141．331．331．56≥1．56齊穗期Fullheadingstage68<0．940．941．091．091．271．271．48≥1．48

注(Note): DAT—Days after the transplanting.

2.4 第二功能葉鉀含量作為鉀營養(yǎng)診斷指標的建立

由產(chǎn)量結果可知，本研究所設置的鉀肥梯度為水稻鉀素診斷提供了可行性(圖2)?；貧w分析結果表明，第二功能葉鉀含量和產(chǎn)量適合用對數(shù)方程擬合(圖4)。根據(jù)圖1所示的植株鉀含量診斷指標建立方法，經(jīng)計算得到第二功能葉鉀含量分級指標(表2)。若以最佳產(chǎn)量的95%為臨界值標準，當?shù)诙δ苋~鉀含量在分蘗初期、分蘗盛期、有效分蘗臨界期、拔節(jié)期、孕穗期和齊穗期分別低于1.34%、1.58%、1.98%、2.09%、1.33%和1.27%時，則需要追施鉀肥以避免水稻植株因缺鉀而導致減產(chǎn)。

3 討論

3.1 第二功能葉鉀含量的變化及差異

3.2 第二功能葉作為鉀素診斷指標的可行性分析

水稻從分蘗期到齊穗期對鉀素的需求占整個生育期的80%以上[23-24]，掌握該階段的水稻鉀素營養(yǎng)狀況對作物正常生長及產(chǎn)量形成具有重要的意義。本文研究發(fā)現(xiàn)各生育期的第二功能葉鉀含量與產(chǎn)量和施鉀量相關關系極顯著；從取樣原則上來講，第二功能葉存在于整個生育期，而且該葉位葉片容易獲取并對作物的損壞程度小。綜上所述，以水稻主莖第二功能葉作為分蘗期到齊穗期的營養(yǎng)診斷部位是可行的。施用效果顯著為鉀營養(yǎng)診斷提供了可靠的保證。陳新平等[25]認為，在對肥效模型進行評價時，應該從模型的擬合程度和推薦施肥量的節(jié)省程度兩方面綜合考慮。本研究用二次加平臺模型進行擬合的程度遠高于其他模型，而且節(jié)省鉀肥；通過肥效方程以及第二功能葉鉀含量的回歸方程，建立了營養(yǎng)診斷指標，既節(jié)約鉀資源，又保證較高的經(jīng)濟產(chǎn)出。

本研究闡明了以功能葉片鉀含量作為鉀營養(yǎng)診斷指標的可行性，初步建立了該試驗條件下各生育期水稻植株鉀營養(yǎng)診斷指標；然而該研究結果是否受種植品種、種植時期及氣候環(huán)境等諸多因素的影響，仍需進行深入研究。

4 結論

3)第二功能葉鉀含量作為植株鉀營養(yǎng)診斷指標的操作性較強，且能夠精準地預測稻谷產(chǎn)量水平。若以95%為產(chǎn)量臨界值標準，在該試驗條件下，當?shù)诙δ苋~鉀含量在分蘗初期、分蘗盛期、有效分蘗臨界期、拔節(jié)期、孕穗期和齊穗期分別低于1.34%、1.58%、1.98%、2.09%、1.33%和1.27%時，則水稻植株處于鉀素缺乏水平，需要補充鉀肥以維持正常的鉀素需求。

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Feasibility study of using potassium content of functional leaves of rice as potassium diagnostic index

XUE Xin-xin, LI Lan-tao, LU Jian-wei*, LI Xiao-kun, REN Tao, CONG Ri-huan, ZHOU Li

(CollegeofResourcesandEnvironment,HuazhongAgriculturalUniversity/KeyLaboratoryofArableLandConservationofMiddleandLowerReachesofYangtzeRiver,MinistryofAgriculture,Wuhan430070,China)

【Objectives】 Plant tissue is widely used for the diagnose of plant nutrient status. The second functional leaf from the top of rice is easy sampled, with negligible injury to rice growth, and will not absciss during the whole growth stages. The feasibility of using the potassium content in the 2nd functional leaf as rice nutrition diagnosis method was studied. 【Methods】 A field experiment was conducted with different K2O application rates of 0, 60, 120, 180, 240, 300 and 360 kg/ha. The potassium contents in the 2nd functional leaf were tested at different growth periods and the grain yields were weighed. Regression analysis was performed to evaluate the relationship between the potassium contents in the 2nd functional leaf and the grain yields and K application rates. 【Results】 The grain yields are significantly different under different K application rates. A quadratic plus plateau model well descriped the significant relationship between K application rates and the grain yield, satisfies the requirement of potassium status diagnosis. The potassium contents of the 2nd functional leaves was increased significantly with the increase of the K application rates. The K contants of the 2nd functional leaves was in range of 0.85%-2.72% from the beginning of the tillering stage to the full heading stage and reach the highest values at the jointing stage. The correlation analysis shows that the potassium content of the 2nd functional leaves were significantly correlated with the grain yield and potassium application rates (P<0.05). The yields are classified as five ranks, i.e., <85%, 85%-90%, 90%-95%, 95%-100% and >100% of the maximum yield. The corresponding K contents of the 2nd functional leaves were calculated according to the regression equation. When the 95% of optimal yield was set as the critical yield, the calculated K contents were 1.34%, 1.58%, 1.98%, 2.09%, 1.33% and 1.27% at initial tillering, active tillering, effective tillering, jointing, booting and full heading stages, respectively.【Conclusions】 The potassium content of the 2nd functional leaves are significantly related to the K2O application rates and yields, so, is suitable to be used as the potassium status diagnosis index at the different rice development periods. If the 95% of optimum yield is set as the critical yield level, rice would be found potassium deficiency when the 2nd functional leaf contents are below 1.34%, 1.58%, 1.98%, 2.09%, 1.33% and 1.27% at the tillering stage, active tillering stage, effective tillering critical stage, jointing stage, booting stage and full heading stage, respectively.

rice; functional leaf; potassium status; diagnostic index

2014-01-02 接受日期： 2014-05-04

公益性行業(yè)(農(nóng)業(yè))科研專項 (201203013)；中央高?；究蒲袠I(yè)務費專項(2013PY113)；長江學者和創(chuàng)新團隊發(fā)展計劃項目(IRT1247)資助。

薛欣欣(1986—)， 男， 陜西咸陽人， 博士研究生， 主要研究作物養(yǎng)分管理方面的研究。E-mail: xuexinxin.2010@webmail.hzau.edu.cn * 通信作者 Tel: 027-61379276, E-mail: lunm@mail.hzau.edu.cn

S158.3； S511.01

A

1008-505X(2015)02-0492-08