提高現(xiàn)代超級稻產(chǎn)量潛力的栽培生理研究途徑探討

顧駿飛陳穎 毛倚琦

（揚(yáng)州大學(xué)江蘇省作物遺傳生理國家重點(diǎn)實(shí)驗(yàn)室培育點(diǎn)/糧食作物現(xiàn)代產(chǎn)業(yè)技術(shù)協(xié)同創(chuàng)新中心，江蘇揚(yáng)州225009；第一作者：gujf@yzu.edu.cn）

提高現(xiàn)代超級稻產(chǎn)量潛力的栽培生理研究途徑探討

顧駿飛陳穎 毛倚琦

（揚(yáng)州大學(xué)江蘇省作物遺傳生理國家重點(diǎn)實(shí)驗(yàn)室培育點(diǎn)/糧食作物現(xiàn)代產(chǎn)業(yè)技術(shù)協(xié)同創(chuàng)新中心，江蘇揚(yáng)州225009；第一作者：gujf@yzu.edu.cn）

水稻籽粒灌漿期同化物供應(yīng)不足會導(dǎo)致籽粒灌漿不充分，從而影響產(chǎn)量，這種現(xiàn)象在大穗型、高庫容的現(xiàn)代超級稻品種中尤為明顯，直接限制了超級稻品種產(chǎn)量潛力的發(fā)揮。灌漿期水稻同化物的供給主要來源于花前同化物的積累與花后同化物的合成，它們均依賴于冠層群體光合能力。因此，加強(qiáng)相關(guān)過程的生理生態(tài)研究對揭示制約現(xiàn)代超級稻產(chǎn)量潛力的關(guān)鍵性因素具有重要意義。作者綜述了相關(guān)領(lǐng)域的研究進(jìn)展，并從葉片光合生理、冠層光氮匹配和根-冠水分平衡等方面，對提高現(xiàn)代超級稻產(chǎn)量潛力的栽培生理途徑進(jìn)行了探討。同時(shí)，作者總結(jié)了模型分析在綜合栽培生理認(rèn)識、發(fā)現(xiàn)超級稻產(chǎn)量潛力限制性因子及其生理機(jī)制等方面的作用。

光合作用；產(chǎn)量潛力；冠層光氮匹配；根-冠水分平衡

現(xiàn)代超級稻品種穗型大，穗粒數(shù)多，有極高的庫容，產(chǎn)量潛力能夠達(dá)到1 000 kg/667m2以上[1]。但是在實(shí)際生產(chǎn)中，以江蘇為例，超級稻單產(chǎn)只在600~700 kg/667 m2之間，且表現(xiàn)出灌漿不充分、結(jié)實(shí)率低，影響了產(chǎn)量潛力的發(fā)揮。超級稻品種的結(jié)實(shí)率往往比常規(guī)稻品種低10%以上[2]?，F(xiàn)代超級稻品種灌漿不充分、結(jié)實(shí)率低，主要原因是灌漿期同化物的供給不充分所造成。要是能突破灌漿期同化物供應(yīng)的瓶頸，將有望進(jìn)一步提高我國超級稻的產(chǎn)量。

灌漿期水稻同化物的供給主要來源于兩個(gè)方面（圖1）：一是花前累積的同化物，它們來源于花前冠層群體的光合，主要以非結(jié)構(gòu)性碳水化合物的形式貯存在莖鞘中，對產(chǎn)量的貢獻(xiàn)為30%左右[3-4]；二是花后冠層群體的光合，其中劍葉光合對產(chǎn)量貢獻(xiàn)較大。以下將分別從葉片光合與冠層光合角度來分析提高水稻凈同化力的限制性因子。

1 葉片光合作用

光合作用是指綠色植物通過葉綠素吸收光能，同化CO2和H2O，制造有機(jī)物并釋放O2的過程，根據(jù)是否需要光的參與，分為光反應(yīng)和暗反應(yīng)兩個(gè)過程。在光反應(yīng)過程中，類囊體上的電子傳遞鏈捕獲和利用光能，合成暗反應(yīng)需要的能量ATP和還原劑NADPH。光反應(yīng)形成的ATP和NADPH供給暗反應(yīng)同化CO2形成碳水化合物。在暗反應(yīng)中，CO2受體為1,5-二磷酸核酮糖（RuBP），在核酮糖二磷酸羧化酶（Rubisco）等一系列酶的作用下，CO2被還原成磷酸丙糖3-磷酸甘油醛（3-GAP）。磷酸丙糖不能直接透過葉綠體內(nèi)膜，其必需由磷酸運(yùn)轉(zhuǎn)器與Pi對等交換才能出入葉綠體。當(dāng)Pi不足或長期光照時(shí)，磷酸丙糖會在葉綠體內(nèi)積累，形成淀粉粒。

因此在低光強(qiáng)下，囊體上的電子傳遞受限，影響ATP的合成，從而影響RuBP再生（RuBP再生限制）；在飽和光強(qiáng)下，暗反應(yīng)關(guān)鍵酶Rubisco的數(shù)量與活性，及反應(yīng)底物CO2的濃度是限制光合作用的最關(guān)鍵因素（Rubisco羧化限制）；在長期光照下，大量形成的光合產(chǎn)物需要借助葉綠體被膜上的磷酸運(yùn)轉(zhuǎn)器及時(shí)運(yùn)轉(zhuǎn)出葉綠體，此時(shí)光合速率受細(xì)胞質(zhì)中無機(jī)磷運(yùn)轉(zhuǎn)速率限制（磷酸丙糖運(yùn)轉(zhuǎn)限制）[5-6]。根據(jù)葉片光合的限制性因子，國內(nèi)外學(xué)者開展了很多研究，希望突破葉片光合限制，提高同化物的供給，例如，通過提高Rubisco活化酶（RCA）的活性來改善Rubisco活性[7]，通過提高Rubisco酶對CO2（相對于O2）的專一性（Sc/o）來改善Rubisco活性[8]，降低光呼吸損耗[9]，過表達(dá)SBPase基因改善RuBP的再生能力[10-11]，通過增加細(xì)胞色素b6f復(fù)合體含量提高葉綠體電子傳遞[12]，引入藍(lán)細(xì)胞的CO2濃縮機(jī)制來提高反應(yīng)底物CO2濃度[13]，過表達(dá)水通道蛋白NtAQP1提高葉肉導(dǎo)度從而提高反應(yīng)底物CO2濃度[14-15]，將高效的C4途徑引入水稻來消除光合作用的氧抑制[16]。但是將這些分子生物學(xué)成果運(yùn)用于水稻的大田生產(chǎn)中，預(yù)計(jì)需要15年甚至更長的時(shí)間[16-17]。針對大田生產(chǎn)中廣泛使用的粳型超級稻品種沈農(nóng)265和農(nóng)家旱稻品種毫格勞，我們對它們及它們雜交組合后代進(jìn)行了遺傳與生理分析，發(fā)現(xiàn)氣孔與葉肉導(dǎo)度是高光強(qiáng)下影響光合最主要的限制性因子[18-19]。Adachi等[20-22]研究發(fā)現(xiàn)，水稻品種Takanari干物質(zhì)積累比水稻品種Koshihikari高20%~30%，主要是因?yàn)門akanari根系具有較高的導(dǎo)水率，能夠維持高的葉片水勢，保持氣孔開發(fā)，有較高的氣孔導(dǎo)度。Yang等[23]也發(fā)現(xiàn)，目前大田高氮肥施用條件下氮素利用效率降低是由于水稻根系導(dǎo)水率低，吸水能力不足，氣孔開放程度低，氣孔導(dǎo)度小所致。因此，如何通過栽培措施調(diào)節(jié)根系、根系-葉片水分平衡，提高氣孔導(dǎo)度，可能是提高水稻光合能力的一個(gè)潛在的靶標(biāo)。

圖1 提高現(xiàn)代超級稻產(chǎn)量潛力的栽培生理途徑分解

2 冠層光合作用

相對于葉片光合，冠層群體的光合與水稻干物質(zhì)的積累、同化物的供應(yīng)聯(lián)系更緊密[24]。冠層結(jié)構(gòu)大大提高了作物光能利用效率。對于水稻等C3作物葉片來說，當(dāng)光合有效輻射（Photosynthetically active radiation, PAR）達(dá)到700~1 000μmol/（m2·s）時(shí)，葉片的光合值達(dá)到上限，光合能力不再隨著光強(qiáng)的提高而增加，稱為光飽和點(diǎn)。而當(dāng)光合有效輻射增加到2 000μmol/（m2s），冠層光合仍然沒有達(dá)到飽和，此時(shí)，冠層光合是葉片光合的3倍[25-26]。這是因?yàn)槌斯趯禹敳康墓怙柡腿~（如劍葉等），冠層內(nèi)陰影部分70%的葉片能夠吸收占總光能30%的散射光與漫射光，貢獻(xiàn)冠層約50%的光合能力[27]。因此，研究整個(gè)冠層的光合生理生態(tài)對水稻的干物質(zhì)積累非常重要。合理的冠層結(jié)構(gòu)歷來受到國內(nèi)外育種和栽培生理專家的重視與關(guān)注[24，28-29]。相關(guān)研究普遍認(rèn)為，莖葉夾角小、直立葉片構(gòu)成的冠層有利于群體受光，對群體光合作用和物質(zhì)生產(chǎn)有利。但在水稻高產(chǎn)實(shí)踐中發(fā)現(xiàn)，基于株型選擇的，具有矮稈、直立葉片等特性的新株型（New type plant-NTP）水稻品種的產(chǎn)量往往比基于產(chǎn)量選擇的超級稻品種的產(chǎn)量低[29]，說明人們對群體冠層結(jié)構(gòu)和功能的認(rèn)識仍然是片面的，不系統(tǒng)的，需要深入理解作物高產(chǎn)群體冠層結(jié)構(gòu)的生理生態(tài)基礎(chǔ)及其與光溫等生態(tài)因子的匹配機(jī)理。

3 提高冠層光合作用的途徑

光是綠色植物進(jìn)行光合作用的能量來源。優(yōu)良的冠層結(jié)構(gòu)有利于光在群體中的分布，有利于群體受光。除了光的分布，氮素作為Rubisco酶與葉綠體的重要組成部分，它在冠層中的分布也是限制植物體內(nèi)物質(zhì)合成的關(guān)鍵因素[30-32]。和光一樣，氮素在冠層內(nèi)的分布也呈現(xiàn)頂部高、基部低的梯度分布。這種氮素的梯度分布相對于均勻分布，冠層光合提高了20%[33]，這種現(xiàn)象被認(rèn)為是植物對外界光環(huán)境的適應(yīng)，是為了提高冠層光合同化力和氮素利用效率[33-35]。但是通常冠層中氮素的分布并不是最優(yōu)的[36-38]，Hikosaka等[39]通過研究發(fā)現(xiàn)，如果能夠調(diào)控冠層中的氮素分布，使之與光的分布一致，達(dá)到最優(yōu)，冠層光合能額外再提高20%。Dingkuhn等[40]在1991年就提出，優(yōu)化冠層氮的分布（即加大氮素的分布梯度差，增加上部葉片含氮量，減少下部葉片含氮量）應(yīng)該作為育種中的重要選擇靶標(biāo)。但是，氮素在冠層中的分布調(diào)控機(jī)理非常復(fù)雜，除了光強(qiáng)外，也受其他因素調(diào)控，如環(huán)境中紅光/遠(yuǎn)紅光比例[41]、植株體內(nèi)激素[42]、葉齡[32]、庫源關(guān)系[31]等。在栽培調(diào)控措施方面，Hikosaka等[34，43-44]的研究表明，高施氮水平能夠改善氮素與光的梯度分布，但是受發(fā)育時(shí)期影響[45]。而Sinclair等[46-47]卻持不同觀點(diǎn)，認(rèn)為氮肥水平對光、氮的分布沒有影響。因此，在生產(chǎn)中栽培措施能否優(yōu)化光、氮分布，充分利用植株體內(nèi)氮素與光合效率空間梯度特點(diǎn)，實(shí)現(xiàn)作物群體光合效率的最大化，值得深入探討。鑒于冠層光合的復(fù)雜性，冠層中的光、氮分布及其對冠層光合的貢獻(xiàn)研究常常借助于模型模擬分析[27，39，48-50]。同時(shí)，植物冠層群體是動態(tài)變化的，苗期葉片的快速生長與冠層結(jié)構(gòu)的建成，有利于光的有效截獲和花前干物質(zhì)的積累[40，51]。開花后作物氮素吸收、分配與植株體內(nèi)氮素代謝影響著冠層光合持續(xù)期長短及其與光溫資源的合理匹配，最終決定品種產(chǎn)量潛力是否能充分發(fā)揮。以往的作物模型研究結(jié)果[50，52]為定量評價(jià)這些因子對提高超級稻產(chǎn)量潛力的影響打下了很好的基礎(chǔ)。

綜上所述，作者建議從葉片光合生理（光合電子傳遞、Rubisco酶含量與活性、氣孔與葉肉導(dǎo)度、葉綠體發(fā)育狀況、磷酸丙糖運(yùn)轉(zhuǎn)等）、冠層光氮匹配（冠層光氮分布、氮素代謝、激素調(diào)控等）和根-冠水分平衡（根莖葉木質(zhì)部發(fā)育、根系導(dǎo)水率、水通道蛋白表達(dá)等）這幾個(gè)方面開展下一步研究，并在此基礎(chǔ)上利用模型分析方法為輔助，揭示現(xiàn)代超級稻品種實(shí)現(xiàn)產(chǎn)量潛力的關(guān)鍵制約因素及其生理調(diào)控基礎(chǔ)，并提出相應(yīng)的栽培調(diào)控手段。

[1]央廣網(wǎng).農(nóng)業(yè)部通報(bào)：“超級稻”畝產(chǎn)已過千公斤[EB/OL].http:// china.cnr.cn/NewsFeeds/201410/t20141010_516575617.shtml.

[2]Yang J，Zhang J.Grain-filling problem in‘super’rice[J].JExp Bot, 2010,61:1-5.

[3]Gebbing T,Schnyder H.Pre-anthesis reserve utilization for protein and carbohydratesynthesis in grainsofwheat[J].PlantPhysiol,1999, 121:871-878.

[4]TakaiT,Fukuta Y,Shirawa T,etal.Time-relatedmappingofquantitative trait loci controlling grain-flling in rice[J].JExp Bot,2005, 56:2 107-2 118.

[5]Farquhar GD,von Caemmerer S,Berry JA.A biochemicalmodel of photosynthetic CO2assimilation in leaves of C3species[J].Planta, 1980,149:78-90.

[6]von Caemmerer S,FarquharG,Berry J.BiochemicalmodelofC3photosynthesis[C]//Laisk A,Nedbal L,Govindjee G,etal.Photosynthesis in silico:Understanding complexity frommolecules toecosystems. Dordrecht,The Netherlands:Springer,2009:209-230.

[7]Kumar A,Li C,Portis Jr A R.Arabidopsis thaliana expressing a thermostable chimeric Rubisco activase exhibits enhanced growth and higher rates of photosynthesis atmoderately high temperatures [J].Photosynth Res,2009,100:143-153.

[8]Raines C A.Increasing photosynthetic carbon assimilation in C3plants to improve crop yield:current and future strategies Photosynthesis[J].Plantphysiol,2011,155:36-42.

[9]Kebeish R,Niessen M,Thiruveedhi K,etal.Chloroplastic photorespiratory bypass increases photosynthesis and biomass production in Arabidopsis thaliana[J].NatBiotechnol,2007,25:593-599.

[10]Miyagawa Y,TamoiM,Shigeoka S.Overexpression of a cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphosphatase in tobacco enhances photosynthesis and growth[J].Nat Biotechnol,2001,19: 965-969.

[11]Stitt M,Lunn J,Usadel B.Arabidopsis and primary photosynthetic metabolism-more than the icing on the cake[J].Plant J,2010,61: 1 067-1 091.

[12]YamoriW,TakahashiS,Makino A,etal.The rolesof ATPsynthase and the cytochrome b6/f complexes in limiting chloroplast electron transportand determining photosynthetic capacity[J].Plant Physiol, 2011,155:956-962.

[13]Lieman-Hurwitz J,Rachmilevitch S,Mittler R,etal.Enhanced photosynthesis and growth of transgenic plants thatexpress ictB,a gene involved in HCO3-accumulation in cyanobacteria[J].PlantBiotechnol J,2003,1:43-50.

[14]Flexas J,Ribas-CarbóM,Hanson D T,et al.Tobacco aquaporin NtAQP1 is involved in mesophyll conductance to CO2in vivo[J]. Plant J,2006,48:427-439.

[15]Sade N,Gebretsadik M,Seligmann R,et al.The role of tobacco Aquaporin1 in improvingwater useefficiency,hydraulic conductivity,and yield production under salt stress[J].Plant Physiol,2010, 152:245-254.

[16]von Caemmerer S,Quick W P,Furbank R T.The developmentof C4rice:currentprogressand future challenges[J].Science,2012,336: 1 671-1 672.

[17]Sheehy JE,Ferrer A B,Mitchell P L,etal.How the rice crop works and why itneedsanew engine[C]//Sheehy JE,Mitchell PL,Hardy B,eds.Charting new pathways to C4rice,Los Ban~os,Philippines: InternationalRice Research Institute,2008:3-26.

[18]Gu J,Yin X,Struik PC,etal.Using chromosome introgression lines to map quantitative trait loci for photosynthesis parameters in rice（Oryza sativa L.）leavesunder droughtand wellwatered field conditions[J].JExp Bot,2012,63:455-469.

[19]Gu J,Yin X,Stomph T J,et al.Physiological basis of genetic variation in leafphotosynthesisamong rice（Oryza sativa L.）introgression linesunder droughtand well-watered conditions[J].JExp Bot,2012, 63:5 137-5 153.

[20]Adachi S,Baptista L Z,Sueyoshi T,et al.Introgression of two chromosome regions for leaf photosynthesis from an indica rice into the genetic background ofa japonica rice[J].JExp Bot,2014,65:2 049-2 056.

[21]Adachi S,Tsuru Y,Nito N,etal.Identification and characterization of genomic regions on chromosomes 4 and 8 that control the rate ofphotosynthesisin rice leaves[J].JExp Bot,2011,62:1927-1938.

[22]Taylaran R D,Adachi S,Ookawa T,etal.Hydraulic conductance as well as nitrogen accumulation plays a role in the higher rate of leaf photosynthesis of themost productive variety of rice in Japan[J].J Exp Bot,2011,62:4 067-4 077.

[23]Yang X,LiY,Ren B,etal.Drought-induced rootaerenchyma formation restrictswater uptake in rice seedlings supplied with nitrate[J]. PlantCell Physiol,2012,53:495-504.

[24]Long SP,Zhu X,Naidu SL,etal.Can improvement in photosynthesis increase crop yields?[J].Plant,Celland Environ,2006,29:315-330.

[25]Zhu XG,Song Q,Ort D R.Elements of a dynamic systemsmodel of canopy photosynthesis[J].CurrOpin PlantBiol,2012,15:237-244.

[26]Evans JR.Improving photosynthesis[J].Plant Physiol,2013,162: 1 780-1 793.

[27]Song Q,Zhang G,Zhu X G.Optimal crop canopy architecture to maximise canopy photosynthetic CO2uptake under elevated CO2-a theoreticalstudyusingamechanisticmodelof canopy photosynthesis [J].FunctPlantBiol,2013,40:108-124.

[28]Duvick DN.Genetic ratesofgain in hybridmaize yieldsduring the past40 years[J].Maydica,1977,22:187-196.

[29]Peng S,Khush GS,Virk P,etal.Progress in ideotypebreeding to increase rice yield potential[J].Field Crop Res,2008,108:32-38.

[30]Grindlay D JC.Towards an explanation of crop nitrogen demand based on theoptimization of leafnitrogen per unit leafarea[J].JA－gric Sci,1997,128:377-396.

[31]DreccerM F,SlaferGA,RabbingeR.Optimization ofverticaldistribution of canopy nitrogen:an alternative trait to increase yield potential inwinter cereals[J].JCrop Prod,1998,1:47-77.

[32]Hikosaka K.Leafcanopy asadynamic system:ecophysiology and optimality in leaf turnover[J].Ann Bot,2005,95:521-533.

[33]Hirose T,Werger M JA.Maximizing daily canopy photosynthesis with respect to the leaf nitrogen allocation pattern in the canopy[J]. Oecologia,1987,72:520-526.

[34]Hikosaka K,Terashima I,Katoh S.Effectsof leafage,nitrogen nutrition and photon flux density on the distribution of nitrogen among leavesofa vine（Ipomoea tricolor Cav.）grown horizontally toavoid mutualshadingof leaves[J].Oecologia,1994,97:451-457.

[35]Drouet JL,Bonhomme R.Do variations in local leaf irradiance explain changes to leaf nitrogen within row maize canopies?[J].Ann Bot,1999,84:61-69.

[36]Pons T L,Schieving F,Hirose T,et al.Optimization of leaf nitrogen allocation for canopy photosynthesis in Lysimachia vulgaris[C]//H Lambers,M L Cambridge,H Konings,et al.Causes and consequencesof variation in growth rate and productivity of higher plants. The Hague,TheNetherlands:SPBAcademic,1989:175-186.

[37]Anten N,Schieving F,Werger M.Patterns of light and nitrogen distribution in relation towhole canopy carbon gain in C3and C4monoand dicotyledonousspecies[J].Oecologia,1995,101:504-513.

[38]Yin X,Lantinga EA,Schapendonk A H CM,etal.Some quantitative relationships between leaf area index and canopy nitrogen contentand distribution[J].Ann Bot,2003,91:893-903.

[39]Hikosaka K.Optimalnitrogen distributionwithin a leafcanopy under direct and diffuse light[J].Plant Cell Environ,2014,37:2 077-2 085.

[40]Dingkuhn M,Penning de Vries FW T,De Datta SK,etal.Concepts foranew plant type for directseeded flooded tropical rice[C].//InternationalRice Research Institute.Directseeded flooded rice in the Tropics.Los Ban~os,Philippines,1991:17-38.

[41]Rousseaux M,Hall A,Sánhez R.Light environment,nitrogen content,and carbon balance of basal leaves of sunflower canopies[J]. Crop Sci,1999,39:1 093-1 100.

[42]Boonman A,Prinsen E,Gilmer F,et al.Cytokinin import rate as a signal for photosynthetic acclimation to canopy light gradients[J]. PlantPhysiol,2007,143:1 841-1 852.

[43]GrindlayD JC,Sylvester-Bradley R,ScottRK.The relationship between canopygreen areaand nitrogen in the shoot[J]//G Lemaire,IG Burns,eds.Diagnostic Procedures for Crop NManagement.Poitiers, France:INRA,1995,82:53-60.

[44]L. o.tscher M,Stroh K,Schnyder H.Vertical leaf nitrogen distribution in relation to nitrogen status in grassland plants[J].Ann Bot,2003, 92:679-688.

[45]DreccerM F,Van Oijen M,Schapendonk A H CM,etal.Dynamics of vertical leaf nitrogen distribution in a vegetative wheat canopy: impacton canopy photosynthesis[J].Ann Bot,2000,86:821-831.

[46]Sinclair TR,Shiraiwa T.Soybean radiation-use efficiency as influenced by nonuniform specific leaf nitrogen distribution and diffuse radiation[J].Crop Sci,1993,33:808-812.

[47]Milroy SP,BangeM P,Sadras VO.Profilesof leafnitrogen and light in reproductive canopiesof cotton（Gossypium hirsutum）[J].Ann Bot,2001,87:325-333.

[48]Prieto JA,Louarn G,Perez Pena J,etal.A leafgasexchangemodel thataccounts for intra-canopy variability by considering leafnitrogen content and local acclimation to radiation in grapevine（Vitis vinifera L.）[J].PlantCellEnviron,2012,35:1 313-1 328.

[49]Chen TW,Henke M,de Visser PH,etal.What is themost prominent factor limiting photosynthesis in different layersofa greenhouse cucumber canopy?[J].Ann Bot,2014,114:677-688.

[50]Gu J,Yin X,Stomph T J,etal.Can exploiting natural genetic variation in leaf photosynthesis contribute to increasing rice productivity? A simulation analysis[J].PlantCell Environ,2014,37:22-34.

[51]Richards R A.Selectable traits to increase crop photosynthesis and yield ofgrain crops[J].JExp Bot,2000,51:447-458.

[52]Gu J,Yin X,Zhang C,etal.Linkingecophysiologicalmodellingwith quantitative genetics to supportmarker-assisted crop design for improved yieldsof rice（Oryza sativa）under droughtstress[J].Ann Bot, 2014,114:499-511.

Approaches to Improve Yield Potential of Super-rice from a Crop Physiological Perspective

GU Junfei,CHEN Ying,MAO Yiqi
（Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops,Yangzhou University,Yangzhou,Jiangsu 225009,China;1st author:gujf@yzu.edu.cn）

Rice yield production is limited by the carbohydrate supply during grain-filling,which is unable to fill the large number of florets of rice plants,especially in the newly bred super-ricewith numerous spikelets in a panicle.During grain-filling stage,carbohydrate supply depends on carbon from two sources:current photosynthetic assimilates and pre-stored assimilates in culms and leaf sheaths of rice plants.It is necessary to conduct the ecophysiological study on the sources of carbohydrate supply,which would enhance our understanding of limitations to yield potential inmodern super-rice.The author summarized recent progresses in this field, and proposed that yield potential ofmodern‘super’rice could be improved by exploring ecophysiological properties of leaf photosynthesis,interaction of light and nitrogen distribution within canopy,and the relationship between root water uptake and leaf water potential.In the end,the author emphasized the role ofmodelling in integrating crop physiological knowledge to find the limitations to realizing super-rice yield potential and its physiological basis.

photosynthesis;yield potential;light and nitrogen distribution within canopy;relationship between root water uptake and leafwater potential

S511.048

：A

：1006-8082（2017）03-0001-05

2016－11－20

國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃（“973”計(jì)劃）（2015CB150400）；國家自然科學(xué)基金（31501254）；江蘇省自然科學(xué)基金（BK20140480）；中國博士后基金（2014M550312,2015T80590）；江蘇省高校自然科學(xué)基金（14KJB210007）