玉米根系特征与其整体水分关系研究
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摘要
本研究以玉米(Zea mays L.)一组遗传材料杂交种户单四号(F1代)及其父本478(♂)、母本天四(♀)和F2代为试验对象，通过一系列溶液培养和干早盆盆栽试验，对玉米根系特征与其整体水分关系中的一些重要问题，诸如(1)玉米根系水力学特征与其整体水分关系；(2)玉米根系形态学特征与其表型抗旱性、水分利用效率的关系；(3)玉米单根水导与整株根系水导、总表面积与有效吸收面积的关系；(4)N、P营养影响玉米根系特征并调控其水分关系机制等进行了研究，取得了如下主要结论：
1．在溶液培养条件下研究了玉米根系水导(Root hydraulic conductivity,Lp_r)与其抗旱性间的关系，发现整株根系水导(Whole roots hydraulic conductivity,Lp_(wr))与品种抗旱性间具有显著的正相关关系，而单根水导(Signal root hydraulic conductivity,Lp_(sr))与抗旱性间无相关或相关不显著。F1代在正常水分和-0.2MPa的PEG胁迫下，其整株根系水导均最高，和父本478相比较，达到极显著水平，和母本天四比较，达到显著水平。而天四的单根水导最高。就是说，在水分亏缺下，F1代植株根系的开源能力最强。相反，在干旱胁迫下，F1代的气孔导度最小，和母本相比较达到显著水平，可见其节流能力也最强。这种水分利用上的开源节流能力可能正是F1代既抗旱又丰产的原因。干旱胁迫下，F1代和母本的叶渗透均降低，但和正常供水相比，母本下降最显著，说明母本的渗透调节能力最强，这便解释了母本整株根系水导低于F1代，气孔导度大于F1代，但其表型仍抗旱的缘故，只是产量低于F1代。整株根系水导与叶水势、叶片净光合速率、地上部干物质重、蒸腾速率、气孔导度间均成正相关关系。
2．在溶液培养条件下，研究了玉米根系单根水导与整株根系水导，总表面积(WRS)与有效吸收面积(ARS)间的关系。发现单根水导与整株根系水导间成非直线的正相关关系，随着环境的变化，根系发育状况和生理活性跟着变化，造成二者不同步。有效吸收面积ARS与根系总表面积WRS的比值具有品种间的差异。御旱型的抗旱品种(如杂交一代户单四号)其ARS/WRS值显著高于耐旱型品种(如母本天四)，前者的产量和耗水量也显著高于后者，但其水分利用效率也高。
3．在盆栽条件下，研究了玉米根系形态特征与其水分利用效率间的关系。发现水分利用效率具有显著的品种和处理间的差异。用水分利用效率与总根长，根系表面
积和根系生物量之间作回归分析发现，其趋势基本相同，均呈三次曲线关系。即
当根系生物量、总根长和表面积相对较小时，随着生物量、总根长和表面积的增
加，水分利用效率也增大。但当这些值增加到一定程度后，水分利用效率开始下
降。由于水分利用效率的提高有望将高产和节水结合起来，因此用水分利用效率
的高低可以反映根系特征的优化，进而有助于筛选高产且节水的玉米品种。
4.在人工气候室水培条件下，用PEG一6000模拟干旱胁迫(渗透势为一0.2Mpa)从单
根和整株根系两个层次上研究了水肥单因子及水肥交互作用与玉米根系水力学
导度间的关系。发现正常供水与水分胁迫下N、P亏缺均使玉米单根水导和整株
根系水导降低，但与N亏缺相比，P亏缺的植株具有较高的整株根系水导和较低
的单根水导。根系性状测定表明，水肥胁迫下玉米根系性状发生了可塑性变化，
造成整株根系干重、侧根数，根毛密度，总根长和总吸收面积的变化，而且这种
可塑性具有营养处理间的差异。与水氮胁迫相比，水磷胁迫下的植株具有较多的
侧根数和较大的根毛密度，从而增加了根系总吸收面积，具有较高的整株根系水
导。Hg抑制试验表明，P亏缺对水通道蛋白的影响大于N亏缺，所以低P处理
具有较低的单根水导。可见，N、P营养对单根水导和整株根系水导的影响不同，
两种营养作用的机理不同。水分胁迫下，施P主要可提高玉米单根水导，而施N
可增加玉米根系总吸收面积，总之都能提高玉米根系水导。而营养胁迫下，供水
可增加根长，减小气孔阻力，增大蒸腾。与水分或营养单因子胁迫相比，水肥双
因子胁迫对根系水导的影响更大，相反，水肥协同供应，能够显著地提高玉米的
根系水导。水肥双因子胁迫下的玉米植株，其根系水力学特征和形态学特征不只
是水分和营养单因子胁迫时效应的数学累加，水肥之间具有互作效应。
Using four maize genotype F1(HD4), ♂(478), ♀(TS) and F2 as materials, some important aspects in the root traits and whole water relations were studied under solution culture and plotted, including:
(1) relationship between root hydraulic conductivity(Lpr)of maize and its water status.
(2) Effect of maize root morphological traits on it's drought resistance and water use efficiency(WUE).
(3) Relationship between signal root hydraulic conductivity(Lpsr) and whole roots system hydraulic conductivity(Lpwr) of maize, as well as relationship between whole root surface area(WRS) and active root surface area (ARS).
(4) Mechanism of N, P nutrition regulate to water relation through affecting roots traits. The major conclusions are as the follows:
1 Solution culture method was used to study the relationship between Lpr and drought resistance. The results indicated that there is a significant positive co-relation between Lpwr and drought resistance, but no significant co-relation between Lpsr and drought resistance. Under both normal water supply and water stress by -0.2MPa PEG, Fl has a higher Lpwr while has a higher Lpsr, which means that Fl can maintain capacity of continually absorbing water from dry soil under water deficiency condition. At the same time, Fl has a lower Cs compared with other two genotypes, which means that Fl can effectively resist water transpiration under water deficiency. This capacity of exploring new source and blocking transpiration flow in water use maybe account for the Fl's higher drought resistance. However, under water deficiency, as a lower Vs, which means that it has higher osmotic adjustment attribute to its drought resistance. There is a significant positive co-relation between Lpw and leaf V s, Pn, Tr and C
s.
2 The relationship between Lpsr and Lpwr, relationship between WRS and ARS as well were studied under solution culture conditions. The results indicated that there is a positive but not linear relation between Lpsr and Lpwr. Whole root surface area (WRS) and active root surface area (ARS)are two different defmations , the former contribute to root bio-mass, and the later to roots' metabolism activity. There is a difference among genotype in ratio of ARS to WRS. The drought resistance genotype (such as Fl) has a significant higher ARS/WRS than that of drought tolerant genotype(such as $), the former has a
higher water use and WUE.
3 The relationship between root characteristics and WUE on maize was studied under plotted conditions. The result indicated that there is a remarkable difference in varieties and different treatments. Regressive analysis of WUE and total roots length, roots system surface area and its bio-mass present three times curve relation. Their trends were basically similar. Namely when roots bio-mass, total root length and root surface area were relative lower, with the increase of bio-mass, total roots length and area, the WUE increased too. However, when those parameters increased to certain value, the WUE began to drop.
4 Using artificial growth chamber, the relationship between water, fertilizer, also the reciprocations of them and maize root system hydraulic conductivity were studied from single root and whole root systems level under PEG-6000 simulating drought stress conditions. The results demonstrated that single root hydraulic conductivity and whole root system hydraulic conductivity were decreased under N, P deficit either water supply or water deficit. But the Lpwr was higher and Lpsr was lower under P deficit than N deficit. Moreover, root system properties took place plastic changes under water and fertilizer stress, including dry weight of whole root systems, lateral root numbers, root hair density, total roots length and absorbing area. And this kind of plasticity has difference of dealing with one of nutrition. Compared with water and nitrogen deficit, more lateral root and deeper root hair density under P stress can increase total root system absorbing area and Lpwr. Hg inhibition experiment indicated that
i
1．在溶液培养条件下研究了玉米根系水导(Root hydraulic conductivity,Lp_r)与其抗旱性间的关系，发现整株根系水导(Whole roots hydraulic conductivity,Lp_(wr))与品种抗旱性间具有显著的正相关关系，而单根水导(Signal root hydraulic conductivity,Lp_(sr))与抗旱性间无相关或相关不显著。F1代在正常水分和-0.2MPa的PEG胁迫下，其整株根系水导均最高，和父本478相比较，达到极显著水平，和母本天四比较，达到显著水平。而天四的单根水导最高。就是说，在水分亏缺下，F1代植株根系的开源能力最强。相反，在干旱胁迫下，F1代的气孔导度最小，和母本相比较达到显著水平，可见其节流能力也最强。这种水分利用上的开源节流能力可能正是F1代既抗旱又丰产的原因。干旱胁迫下，F1代和母本的叶渗透均降低，但和正常供水相比，母本下降最显著，说明母本的渗透调节能力最强，这便解释了母本整株根系水导低于F1代，气孔导度大于F1代，但其表型仍抗旱的缘故，只是产量低于F1代。整株根系水导与叶水势、叶片净光合速率、地上部干物质重、蒸腾速率、气孔导度间均成正相关关系。
2．在溶液培养条件下，研究了玉米根系单根水导与整株根系水导，总表面积(WRS)与有效吸收面积(ARS)间的关系。发现单根水导与整株根系水导间成非直线的正相关关系，随着环境的变化，根系发育状况和生理活性跟着变化，造成二者不同步。有效吸收面积ARS与根系总表面积WRS的比值具有品种间的差异。御旱型的抗旱品种(如杂交一代户单四号)其ARS/WRS值显著高于耐旱型品种(如母本天四)，前者的产量和耗水量也显著高于后者，但其水分利用效率也高。
3．在盆栽条件下，研究了玉米根系形态特征与其水分利用效率间的关系。发现水分利用效率具有显著的品种和处理间的差异。用水分利用效率与总根长，根系表面
积和根系生物量之间作回归分析发现，其趋势基本相同，均呈三次曲线关系。即
当根系生物量、总根长和表面积相对较小时，随着生物量、总根长和表面积的增
加，水分利用效率也增大。但当这些值增加到一定程度后，水分利用效率开始下
降。由于水分利用效率的提高有望将高产和节水结合起来，因此用水分利用效率
的高低可以反映根系特征的优化，进而有助于筛选高产且节水的玉米品种。
4.在人工气候室水培条件下，用PEG一6000模拟干旱胁迫(渗透势为一0.2Mpa)从单
根和整株根系两个层次上研究了水肥单因子及水肥交互作用与玉米根系水力学
导度间的关系。发现正常供水与水分胁迫下N、P亏缺均使玉米单根水导和整株
根系水导降低，但与N亏缺相比，P亏缺的植株具有较高的整株根系水导和较低
的单根水导。根系性状测定表明，水肥胁迫下玉米根系性状发生了可塑性变化，
造成整株根系干重、侧根数，根毛密度，总根长和总吸收面积的变化，而且这种
可塑性具有营养处理间的差异。与水氮胁迫相比，水磷胁迫下的植株具有较多的
侧根数和较大的根毛密度，从而增加了根系总吸收面积，具有较高的整株根系水
导。Hg抑制试验表明，P亏缺对水通道蛋白的影响大于N亏缺，所以低P处理
具有较低的单根水导。可见，N、P营养对单根水导和整株根系水导的影响不同，
两种营养作用的机理不同。水分胁迫下，施P主要可提高玉米单根水导，而施N
可增加玉米根系总吸收面积，总之都能提高玉米根系水导。而营养胁迫下，供水
可增加根长，减小气孔阻力，增大蒸腾。与水分或营养单因子胁迫相比，水肥双
因子胁迫对根系水导的影响更大，相反，水肥协同供应，能够显著地提高玉米的
根系水导。水肥双因子胁迫下的玉米植株，其根系水力学特征和形态学特征不只
是水分和营养单因子胁迫时效应的数学累加，水肥之间具有互作效应。
Using four maize genotype F1(HD4), ♂(478), ♀(TS) and F2 as materials, some important aspects in the root traits and whole water relations were studied under solution culture and plotted, including:
(1) relationship between root hydraulic conductivity(Lpr)of maize and its water status.
(2) Effect of maize root morphological traits on it's drought resistance and water use efficiency(WUE).
(3) Relationship between signal root hydraulic conductivity(Lpsr) and whole roots system hydraulic conductivity(Lpwr) of maize, as well as relationship between whole root surface area(WRS) and active root surface area (ARS).
(4) Mechanism of N, P nutrition regulate to water relation through affecting roots traits. The major conclusions are as the follows:
1 Solution culture method was used to study the relationship between Lpr and drought resistance. The results indicated that there is a significant positive co-relation between Lpwr and drought resistance, but no significant co-relation between Lpsr and drought resistance. Under both normal water supply and water stress by -0.2MPa PEG, Fl has a higher Lpwr while has a higher Lpsr, which means that Fl can maintain capacity of continually absorbing water from dry soil under water deficiency condition. At the same time, Fl has a lower Cs compared with other two genotypes, which means that Fl can effectively resist water transpiration under water deficiency. This capacity of exploring new source and blocking transpiration flow in water use maybe account for the Fl's higher drought resistance. However, under water deficiency, as a lower Vs, which means that it has higher osmotic adjustment attribute to its drought resistance. There is a significant positive co-relation between Lpw and leaf V s, Pn, Tr and C
s.
2 The relationship between Lpsr and Lpwr, relationship between WRS and ARS as well were studied under solution culture conditions. The results indicated that there is a positive but not linear relation between Lpsr and Lpwr. Whole root surface area (WRS) and active root surface area (ARS)are two different defmations , the former contribute to root bio-mass, and the later to roots' metabolism activity. There is a difference among genotype in ratio of ARS to WRS. The drought resistance genotype (such as Fl) has a significant higher ARS/WRS than that of drought tolerant genotype(such as $), the former has a
higher water use and WUE.
3 The relationship between root characteristics and WUE on maize was studied under plotted conditions. The result indicated that there is a remarkable difference in varieties and different treatments. Regressive analysis of WUE and total roots length, roots system surface area and its bio-mass present three times curve relation. Their trends were basically similar. Namely when roots bio-mass, total root length and root surface area were relative lower, with the increase of bio-mass, total roots length and area, the WUE increased too. However, when those parameters increased to certain value, the WUE began to drop.
4 Using artificial growth chamber, the relationship between water, fertilizer, also the reciprocations of them and maize root system hydraulic conductivity were studied from single root and whole root systems level under PEG-6000 simulating drought stress conditions. The results demonstrated that single root hydraulic conductivity and whole root system hydraulic conductivity were decreased under N, P deficit either water supply or water deficit. But the Lpwr was higher and Lpsr was lower under P deficit than N deficit. Moreover, root system properties took place plastic changes under water and fertilizer stress, including dry weight of whole root systems, lateral root numbers, root hair density, total roots length and absorbing area. And this kind of plasticity has difference of dealing with one of nutrition. Compared with water and nitrogen deficit, more lateral root and deeper root hair density under P stress can increase total root system absorbing area and Lpwr. Hg inhibition experiment indicated that
i
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41． Liao H(廖红)，Yan X L(严小龙)．Adaptive changes and genotypic variation for root architecture of common bean in response to phosphorus deficiency．Acta Botanica Sinica(in Chinese)(植物学报)， 2000，42(2) ：158-163
42． Liao H(廖红)，Ge ZH Y(戈振扬)，Yan X L(严小龙)．Ideal root architecture for phosphorus acquisition of plants under water and phosphorus coupled stresses：from simulation to application． Chinese Science Bulletin(科学通报)，2001，46(8) ：641-646
43． Lidia SAS, Rengel ZED, and Caixian TANG. The effect of Nitrogen nutrition on cluster root formation and proton extrusion by Lupinus albus. Ann Bot,2002, 89:435-442
44． Ligero F et al. Nitrate-and inoculation-enhanced ethylene biosynthesis in soybean roots as a possible mediator of nodulation control. J.Plant Physiol. 1999, 154:482-488
45． Lucas WJ. Application of microinjection techniques to plant nutrition. Plant Soil, 1997, 196:175-189
46． Lynch J and Brown KM. Ethylene and plant response to nutritional stress. Physiol. Plant,1997, 100:613-619
47． Ma Y X(马元喜)ed．The root of sweat(in Chinese)．Bei jing：Chinese Agricultural Press．2000
48． Mackay AD, Barber SA. Effect of soil moisture and phosphate level on root hair growth of corn roots. Plant Soil, 1985, 86: 321-331
49． Maggio A, Joly RJ.Effects of mercuric chloride on the hydraulic conductivity of tomato root systems. Evidence for a channel-mediated pathway. Plant Physiol, 1995,109:331-335
50． Mathesius U. Flavonoids induced in cells undergoing nodule organogenesis in white clover are regulators of auxin breakdown by peroxidase. J Exp Bot, 2001, 52(roots special issue):419-426
51． Miao G Y(苗果园)，Gao ZH Q(高志强)，et al．．Effect of water and fertilizer to root system and its correlation with tops in Wheat．Acta Agronomica Sinica(作物学报)，2002，28(4) ：445-450(in Chinese)
52． Miao G Y(苗果园)，Ju Q X(，Wang L ZH(王理忠)．Effect of P and K fertilizers on the yield of winter wheat in infertile arid land．Scientia Agricultura Sinica(中国农业科学)，1981，6：45-49(in Chinese)
53． Miao G Y(苗果园)，Yin J(尹钧)，et al．．Study on root growth of main crops in north China．Acta Agronomica Sinica(作物学报)，1998，24(1) ：1-6(in Chinese)
54． Mollier A and Pellerin S. Maize root system growth and development as influenced by phosphorus deficiency. J. Exp. Bot. 1999, 50:487-497
55． Morgan, J.A. The effect of N nutrition on the water relation and gas exchange characteristics of wheat, Plant Physiol, 1986, 80:52-58
56． Niemietz CA, Tyerman SD.Characterization of water channels in wheat root membrane vesicles. Plant Physiol, 1997,115:561-567
57． Orsel M, Filleur S, Fraisier V, et al. Nitrate transport in plants: Which gene and which control? J Exp Bot,2002, 53:825-833
58． Radin JW, Matthews MA.Water transport properties of cortical cells in roots of nitrogen-and phosphorus-deficient cotton seedlings. Plant Physiol, 1989,89:264-268
59． Radin, J.w. and Ackerson, R.C.Water relations of cotton plant under nitrogen deficiency: Stomatal conductance, photosynthesis and ABA accumulation during drought, Plant Physiol., 1981,67:115-119
60． Radin, J.w.. Stomatal responses to water stress and to ABA in phosphorus-deficient cotton plants. Plant Physiol., 1984,76:392-394
61． Radin, J.w., Atathews M A. Water transport properties of cortical cells in roots of nitrogen-and phosphorus-deficient cotton seedlings. Plant Physiol., 1989,89: 264-268
62． Radin, J.w., Boyer J S. Control of leaf expansion by nitrogen nutrition in sunflower plants: Role of hydraulic conductivity and tugor. Plant Physiol., 1982,69: 771-775
63． Radin, J.w., Eidenbock M R P. Hydraulic conductance as a factor limiting expansion of phosphorus-deficient cotton plants. Plant Physiol., 1984,75: 372-377
64． Richard Parsons and Sunley RJ. Nitrogen nutrition and the role of root-shoot nitrogen signaling particularly in symbiotic systems. J Exp Bot, 2001,52(roots special issue):435-443
65． Robinson D. The response of plants to non-uniform supplies of nutrients. New Phytol, 1994, 127:635-674
66． Ruize-Medrano R, Xoconostle-Cazares B and Lucas WJ. Phloem long-distance transport of CmNACP mRNA: implications for supracellular regulation in plants. Development,\999, 126:4405-4419
67． Ryan CA. The systemin signaling pathway: differential activation of plant defensive genes. Biochim. Biophys. Acta, 2000,1477:112-121
68． Ryser P, Verduyn B and Lambers H. Phosphorus allocation and utilization in three grass species with contrasting response to N and P supply. New Phytol, 1997, 137:293-302
69． Schmidt W and Schikora A. Different pathways are involved in phosphate and iron stress-induced alterations of root epidermal cell development. Plant Physiol, 2001, 125:2078-2084
70． Schmidt W, Tittel J, and Schikora A. Role of hormones in the induction of iron deficiency responses in Arabidopsis roots. Plant Physiol.2000, 122:1109-1118
71． Schultze M and Kondorosi A. Regulation of symbiotic root nodule development. Ann. Rev. Genet, 1998,32:33-57
72． Shan L(山仑)．Study of water relations and increase agricultural production in Chinese North-West Area．Plant Physiol Commun(植物生理学通讯)，1983，5：7-10(in Chinese)
73． Shan L(山仑)，Sun J B(孙纪斌)et al．A study on production and water use of main crops in southern Ningxia Hilly Area．Scientia Agricultura Sinica(中国农业科学)，1988，21(20：9-16(in Chinese)
74． Shao M-A(邵明安)，Yang W-Z(杨文治)，Li Y-S(李玉山)．Mathematical model of soil moisture absorption by plant roots．Acta Pedol Sin(土壤学报)，1987，4：295-305(in Chinese)
75． Siefritz F, Tyree MT, Lovisoko C, Schubert A, and Kaldenhoff R.PIP 1 plasma membrane aquaporins in tobacco: from cellular effects to function in plants. Plant Cell, 2002,10． 1105/tpc.000901
76． Skene KR. Cluster roots: model experimental tools for key biological problems. J Exp Bot, 2001,52(roots special issue):479-485
77． Skene KR. Cluster roots: some ecological considerations. Journal of 'Ecology, 1998, 86:1060-1064
78． Skinner R H, Radin J W. The effect of phosphorus nutrition on water flow through the apoplastic bypass in cotton roots. J. Exp. Bot., 1994,45(273) : 423-428
79． Snapp S, Koide R and Lynch J. Exploitation of localized phosphorus-patches by common bean roots. Plant Soil, 1995, 177,211-218
80． Steudle E.Water uptake by roots: effects of water deficit. J Exp Bot,2000a,51 (Special Issue): 1531-1542
81． Steudle E.Water uptake by plant roots: an integration of views. Plant Soil, 2000b,26:45-56
82． Steudle E.The cohesion-tension mechanism and the acquisition of water by plant roots. Annu. Rev. Plant Physiol. Plant Mol. Biol,2001, 52:847-75
83． Sun H G(孙海国)，Zhang F S(张福锁)．Growth response of wheat roots to phosphorus deficiency． Acta Botanica Sinica(in Chinese)(植物学报)，2000，42(9) ：913-919
84． Tazawa M, Sotou E, and Shibasaka M. Onion root water transport sensitive to water channel and K+ channel inhibitors. Plant Cell Physiol, 2001,42:28-36
85． Tester M and Leigh RA. Partitioning of nutrient transport processes in roots. J Exp Bot, 2001, 52(roots special issue):445-457
86． Thompson GA and Schulz A. Macromolecular trafficking in the phloem. Trends Plant Sci, 1999,4: 354-360
87． Trull MC et al. The response of wild-type and ABA mutant Arabdopsis thaliana plants to phosphorus starvation. Plant cell Environ, 1997, 20:85-92
88． Tyerman SD, Bohnert HJ , Maurel C, Steudle and Smith JAC. Plant aquaporins: their molecular biology, biophysics and significance for plant water relations. J Exp Bot,1999, 50:1055-1071
89． Wang SH-T(王韶唐)．Plant water use efficiency(WUE)and agricultural production in dry land． Agricultural Research in the Arid Areas(干旱地区农业研究)，1987，2：67-80(in Chinese)
90． Watt M and Evans JR. Proteoid roots, Physiology and development. Plant Physiol 1999,121:317-323
91． Whiting SN. Leake JR, McGrath SP and Baker AJM. Positive response to Zn and Cd by roots of the Zn and Cd hyperaccumulator Thlaspi caerulescens. New Phytol, 2000, 145:199-210
92． Williamson LC, Ribrioux SPCP et al. Phosphate availability regulates root system architecture in Arabidopsis. Plant Physiol, 2001,126:875-882
93． Wissuwa M and Ae N. Genotypic differences in the presence of hairs on roots and gynophores of peanuts (Arachis hypogaea L.)and their significance for phosphorus uptake. J Exp .Bot,2001, 52:1703-1710
94． Xian CW and Zwiazek JJ. Mercuric chloride effects on root water transport in aspen seedlings. Plant Physiol, 2000, 121 :939-946
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96． Xu M(徐萌)，Shan L(山仑)．Effects of inorganic nutrition on the water status and osmotic adjustment of spring wheat under different water conditions．Acta Botanica Sinica(植物学报)， 1992，34(8) ：596-602(in Chinese)
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104． Zhang WH, and Tyerman SD Inhibition of water channels by HgC12 in intact wheat root cells. Plant Physiol, 2000,120:849-858
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24． Fang-Qing Guo, Rong-Chen Wang, and Crawford MM. The Arabidopsis dual-affinity nitrate transporter gene AtNRTl.1(CHL1) is regulated by auxin in both shoots and roots. J Exp Bot, 2002, 53: 835-848
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28． Forde BG. The role of long-distance signaling in plant responses to nitrate and other nutrients. J Exp Bot, 2002, 53:39-43
29． Ge ZY, Rubio G and Lynch JP. The importance of root gravitropism for inter-root competition and phosphorus acquisition efficiency: results from a geometric simulation model. Plant Soil, 2000, 218:159-171
30． Genoud T and Metraux JP. Crosstalk in plant cell signaling: Structure and function of the genetic network. Trends Plant Sci, 1999, 4:503-507
31． Gilbert GA, Knight JD et al. Proteoid root development of phosphorous deficient lupin is mimicked by auxin and phosphonate. Ann.Bot.2000, 85:921-928
32． Gilroy S and Jones DL. Through form to function: root hair development and nutrient uptake. Trends Plant Sci,2000, 5:56-60
33． Gordon AJ, .James SL and Minchin FR. Short-term metabolic responses of soybean root nodules to nitrate. J Exp Bot, 2002, 53:423-428
34． Gould SF. Proteoid root mats bind surface materials in Hawkesbury Sandstone biomantles. Australian Journal of Soil Research, 1998a, 36:1019-1031
35． Gould SF. Proteoid root mats stabilize Hawkesbury Sandstone biomantles following fire. Australian Journal of Soil Research, 1998b, 36:1033-1043
36． Hoarau J, Barthes L, Bousser A, Deleens E, Prioul JL.Effect of nitrate on water transfer across roots of nitrogen pre-starved maize seedlings.Planta, 1996,200:405-415
37． Hodge A, Robinson D, Griffiths BS and Fitter AH. Why plants bother: root proliferation results in increased nitrogen capture from an organic patch when two grasses compete. Plant Cell Environ, 1999,22: 811-820
38． Huang M B(黄明斌)，Dong C Y(董翠云)．An improved technique for measuring root radial hydraulic conductivity．Acta Botanica Sinica(植物学报)，2000，42(9) ：927-930(in Chinese)
39． Li H P(李海波)，Xia M(夏铭)，Wu P(吴平)．Effect of phosphorus deficiency stress on rice lateral root growth and nutrient absorption．Acta Botanica Sinica(in Chinese)(植物学报)， 2001，43(11) ：1154-1160
40． Li J Y(李继云)，Liu X D(刘秀娣)，Zhou W(周伟)et al．Study on crop breeding new technology about efficiently utilizing nutrient in soil．Chinese science(B)(中国科学B)，1995，25(1) ：41-48
41． Liao H(廖红)，Yan X L(严小龙)．Adaptive changes and genotypic variation for root architecture of common bean in response to phosphorus deficiency．Acta Botanica Sinica(in Chinese)(植物学报)， 2000，42(2) ：158-163
42． Liao H(廖红)，Ge ZH Y(戈振扬)，Yan X L(严小龙)．Ideal root architecture for phosphorus acquisition of plants under water and phosphorus coupled stresses：from simulation to application． Chinese Science Bulletin(科学通报)，2001，46(8) ：641-646
43． Lidia SAS, Rengel ZED, and Caixian TANG. The effect of Nitrogen nutrition on cluster root formation and proton extrusion by Lupinus albus. Ann Bot,2002, 89:435-442
44． Ligero F et al. Nitrate-and inoculation-enhanced ethylene biosynthesis in soybean roots as a possible mediator of nodulation control. J.Plant Physiol. 1999, 154:482-488
45． Lucas WJ. Application of microinjection techniques to plant nutrition. Plant Soil, 1997, 196:175-189
46． Lynch J and Brown KM. Ethylene and plant response to nutritional stress. Physiol. Plant,1997, 100:613-619
47． Ma Y X(马元喜)ed．The root of sweat(in Chinese)．Bei jing：Chinese Agricultural Press．2000
48． Mackay AD, Barber SA. Effect of soil moisture and phosphate level on root hair growth of corn roots. Plant Soil, 1985, 86: 321-331
49． Maggio A, Joly RJ.Effects of mercuric chloride on the hydraulic conductivity of tomato root systems. Evidence for a channel-mediated pathway. Plant Physiol, 1995,109:331-335
50． Mathesius U. Flavonoids induced in cells undergoing nodule organogenesis in white clover are regulators of auxin breakdown by peroxidase. J Exp Bot, 2001, 52(roots special issue):419-426
51． Miao G Y(苗果园)，Gao ZH Q(高志强)，et al．．Effect of water and fertilizer to root system and its correlation with tops in Wheat．Acta Agronomica Sinica(作物学报)，2002，28(4) ：445-450(in Chinese)
52． Miao G Y(苗果园)，Ju Q X(，Wang L ZH(王理忠)．Effect of P and K fertilizers on the yield of winter wheat in infertile arid land．Scientia Agricultura Sinica(中国农业科学)，1981，6：45-49(in Chinese)
53． Miao G Y(苗果园)，Yin J(尹钧)，et al．．Study on root growth of main crops in north China．Acta Agronomica Sinica(作物学报)，1998，24(1) ：1-6(in Chinese)
54． Mollier A and Pellerin S. Maize root system growth and development as influenced by phosphorus deficiency. J. Exp. Bot. 1999, 50:487-497
55． Morgan, J.A. The effect of N nutrition on the water relation and gas exchange characteristics of wheat, Plant Physiol, 1986, 80:52-58
56． Niemietz CA, Tyerman SD.Characterization of water channels in wheat root membrane vesicles. Plant Physiol, 1997,115:561-567
57． Orsel M, Filleur S, Fraisier V, et al. Nitrate transport in plants: Which gene and which control? J Exp Bot,2002, 53:825-833
58． Radin JW, Matthews MA.Water transport properties of cortical cells in roots of nitrogen-and phosphorus-deficient cotton seedlings. Plant Physiol, 1989,89:264-268
59． Radin, J.w. and Ackerson, R.C.Water relations of cotton plant under nitrogen deficiency: Stomatal conductance, photosynthesis and ABA accumulation during drought, Plant Physiol., 1981,67:115-119
60． Radin, J.w.. Stomatal responses to water stress and to ABA in phosphorus-deficient cotton plants. Plant Physiol., 1984,76:392-394
61． Radin, J.w., Atathews M A. Water transport properties of cortical cells in roots of nitrogen-and phosphorus-deficient cotton seedlings. Plant Physiol., 1989,89: 264-268
62． Radin, J.w., Boyer J S. Control of leaf expansion by nitrogen nutrition in sunflower plants: Role of hydraulic conductivity and tugor. Plant Physiol., 1982,69: 771-775
63． Radin, J.w., Eidenbock M R P. Hydraulic conductance as a factor limiting expansion of phosphorus-deficient cotton plants. Plant Physiol., 1984,75: 372-377
64． Richard Parsons and Sunley RJ. Nitrogen nutrition and the role of root-shoot nitrogen signaling particularly in symbiotic systems. J Exp Bot, 2001,52(roots special issue):435-443
65． Robinson D. The response of plants to non-uniform supplies of nutrients. New Phytol, 1994, 127:635-674
66． Ruize-Medrano R, Xoconostle-Cazares B and Lucas WJ. Phloem long-distance transport of CmNACP mRNA: implications for supracellular regulation in plants. Development,\999, 126:4405-4419
67． Ryan CA. The systemin signaling pathway: differential activation of plant defensive genes. Biochim. Biophys. Acta, 2000,1477:112-121
68． Ryser P, Verduyn B and Lambers H. Phosphorus allocation and utilization in three grass species with contrasting response to N and P supply. New Phytol, 1997, 137:293-302
69． Schmidt W and Schikora A. Different pathways are involved in phosphate and iron stress-induced alterations of root epidermal cell development. Plant Physiol, 2001, 125:2078-2084
70． Schmidt W, Tittel J, and Schikora A. Role of hormones in the induction of iron deficiency responses in Arabidopsis roots. Plant Physiol.2000, 122:1109-1118
71． Schultze M and Kondorosi A. Regulation of symbiotic root nodule development. Ann. Rev. Genet, 1998,32:33-57
72． Shan L(山仑)．Study of water relations and increase agricultural production in Chinese North-West Area．Plant Physiol Commun(植物生理学通讯)，1983，5：7-10(in Chinese)
73． Shan L(山仑)，Sun J B(孙纪斌)et al．A study on production and water use of main crops in southern Ningxia Hilly Area．Scientia Agricultura Sinica(中国农业科学)，1988，21(20：9-16(in Chinese)
74． Shao M-A(邵明安)，Yang W-Z(杨文治)，Li Y-S(李玉山)．Mathematical model of soil moisture absorption by plant roots．Acta Pedol Sin(土壤学报)，1987，4：295-305(in Chinese)
75． Siefritz F, Tyree MT, Lovisoko C, Schubert A, and Kaldenhoff R.PIP 1 plasma membrane aquaporins in tobacco: from cellular effects to function in plants. Plant Cell, 2002,10． 1105/tpc.000901
76． Skene KR. Cluster roots: model experimental tools for key biological problems. J Exp Bot, 2001,52(roots special issue):479-485
77． Skene KR. Cluster roots: some ecological considerations. Journal of 'Ecology, 1998, 86:1060-1064
78． Skinner R H, Radin J W. The effect of phosphorus nutrition on water flow through the apoplastic bypass in cotton roots. J. Exp. Bot., 1994,45(273) : 423-428
79． Snapp S, Koide R and Lynch J. Exploitation of localized phosphorus-patches by common bean roots. Plant Soil, 1995, 177,211-218
80． Steudle E.Water uptake by roots: effects of water deficit. J Exp Bot,2000a,51 (Special Issue): 1531-1542
81． Steudle E.Water uptake by plant roots: an integration of views. Plant Soil, 2000b,26:45-56
82． Steudle E.The cohesion-tension mechanism and the acquisition of water by plant roots. Annu. Rev. Plant Physiol. Plant Mol. Biol,2001, 52:847-75
83． Sun H G(孙海国)，Zhang F S(张福锁)．Growth response of wheat roots to phosphorus deficiency． Acta Botanica Sinica(in Chinese)(植物学报)，2000，42(9) ：913-919
84． Tazawa M, Sotou E, and Shibasaka M. Onion root water transport sensitive to water channel and K+ channel inhibitors. Plant Cell Physiol, 2001,42:28-36
85． Tester M and Leigh RA. Partitioning of nutrient transport processes in roots. J Exp Bot, 2001, 52(roots special issue):445-457
86． Thompson GA and Schulz A. Macromolecular trafficking in the phloem. Trends Plant Sci, 1999,4: 354-360
87． Trull MC et al. The response of wild-type and ABA mutant Arabdopsis thaliana plants to phosphorus starvation. Plant cell Environ, 1997, 20:85-92
88． Tyerman SD, Bohnert HJ , Maurel C, Steudle and Smith JAC. Plant aquaporins: their molecular biology, biophysics and significance for plant water relations. J Exp Bot,1999, 50:1055-1071
89． Wang SH-T(王韶唐)．Plant water use efficiency(WUE)and agricultural production in dry land． Agricultural Research in the Arid Areas(干旱地区农业研究)，1987，2：67-80(in Chinese)
90． Watt M and Evans JR. Proteoid roots, Physiology and development. Plant Physiol 1999,121:317-323
91． Whiting SN. Leake JR, McGrath SP and Baker AJM. Positive response to Zn and Cd by roots of the Zn and Cd hyperaccumulator Thlaspi caerulescens. New Phytol, 2000, 145:199-210
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