不同供Zn水平下HCO3^-对小麦幼苗生长和活性氧代谢的影响

采用营养液培养法,研究了不同pH条件下高浓度HCO3^-(10mmol／L)在缺Zn和正常供Zn时对小麦幼苗生长,尤其是对活性氧自由基代谢的影响。结果表明,在酸性或碱性营养液中,HCO3^-在缺Zn时均显著降低小麦根系生长量,正常供Zn时HCO3^-对后者的影响则不明显。缺Zn条件下,HCO3^-在pH为6的营养液中使小麦根系和叶片中活性氧产生速率分别上升9．9％和3．9％,在pH为8的营养液中分别上升10．9％和5．7％;正常供Zn时HCO3^-虽使根系和叶片中活性氧产生速率增加,但幅度有所降低。缺Zn时HCO3^-大幅度降低小麦根系中POD、CAT、SOD3种保护酶的活性,而正常供Zn在一定程度上则能缓解HCO3^-对小麦根系组织中膜脂的过氧化作用。正常供Zn与缺Zn相比,后者显著增加小麦根系和叶片中的自氧化速率。     

不同磷效率小麦品种对缺磷胁迫反应的比较

在营养液培养条件下,以根据相对产量为指标筛选出的6个不同磷效率的小麦(Triticum aestivum L.)品种为材料,对其苗期在缺磷条件下生长、根冠磷含量及其分配,以及叶片韧皮部汁液中磷浓度等进行了比较研究.结果表明,缺磷抑制植株地上部生长,但刺激根系生长,导致植株根/冠比增加.无论在供磷或缺磷条件下,磷高效品种的根冠生长速率都低于磷低效品种.缺磷导致植株体内的磷含量下降与根系相比,地上部磷含量的下降速率更快.但在缺磷条件下,不同磷效率的小麦品种根冠间的磷分配变化没有差异.研究发现,在正常供磷条件下,磷高效小麦品种的叶片韧皮部汁液中磷浓度较低,而磷低效品种的叶片韧皮部汁液中磷浓度较高.但开始缺磷后,磷高效品种的叶片韧皮部汁液中的磷浓度下降较慢,使其相对磷浓度较高.缺磷后1 0天,磷低效品种叶片韧皮部汁液中的磷浓度为供磷对照的35.9%,而磷高效品种叶片韧皮部汁液中的磷浓度为供磷对照的59%.     

不同磷效率小麦品种对缺磷胁迫反应的比较

在营养液培养条件下,以根据相对产量为指标筛选出的6个不同磷效率的小麦(Triticum aestivum L.)品种为材料,对其苗期在缺磷条件下生长、根冠磷含量及其分配,以及叶片韧皮部汁液中磷浓度等进行了比较研究。结果表明,缺磷抑制植株地上部生长,但刺激根系生长,导致植株根／冠比增加。无论在供磷或缺磷条件下,磷高效品种的根冠生长速率都低于磷低效品种。缺磷导致植株体内的磷含量下降与根系相比,地上部磷含量的下降速率更快。但在缺磷条件下,不同磷效率的小麦品种根冠间的磷分配变化没有差异。研究发现,在正常供磷条件下,磷高效小麦品种的叶片韧皮部汁液中磷浓度较低,而磷低效品种的叶片韧皮部汁液中磷浓度较高。但开始缺磷后,磷高效品种的叶片韧皮部汁液中的磷浓度下降较慢,使其相对磷浓度较高。缺磷后10天,磷低效品种叶片韧皮部汁液中的磷浓度为供磷对照的35．9％,而磷高效品种叶片韧皮部汁液中的磷浓度为供磷对照的59％。     

缺锌和HCO_3~-处理对诸葛菜和油菜有机酸特征的影响

以诸葛菜和油菜为材料,水培环境下设置4个不同的缺锌和碳酸氢根离子胁迫处理,分别为+Zn0(含Zn且不加HCO3-的处理组),+Zn10(含Zn且加10 mmol·L-1HCO3-的处理组),-Zn0(缺Zn且不加HCO3-的处理组)和-Zn10(缺Zn且加10 mmol·L-1HCO3-的处理组),利用离子色谱法分析了4个处理的两种植物幼苗器官(根、茎、叶)及根系分泌物中的有机酸特征。结果表明:(1)高浓度碳酸氢根离子处理显著增加了两种植物器官及根系分泌的有机酸总量,尤其是在缺锌和高浓度碳酸氢根离子双重胁迫下(-Zn10处理),诸葛菜器官和根系分泌的有机酸比油菜更敏感,草酸、柠檬酸和苹果酸是诸葛菜器官和根系分泌物中的优势酸,这三种有机酸的含量分别占其有机酸总量的75%及以上;(2)叶片是两种植物有机酸产生的主要器官,有机酸的含量和分配比例从地上部分(叶和茎)到地下部分(根)减少;(3)两种植物器官和根系分泌物中的有机酸变化趋势一致,叶片中有机酸主要来源于暗呼吸过程和光呼吸过程,其他器官和根系分泌物中的有机酸主要来源于暗呼吸过程;(4)诸葛菜对缺锌和高浓度碳酸氢根离子的适应能力强于油菜,为诸葛菜的喀斯特适生性和低锌和高浓度碳酸氢根离子环境(如喀斯特环境)的生态修复提供了理论依据。     

供锌条件下碳酸钙对小麦幼苗生长和锌吸收的影响

通过营养液培养试验,研究了供Zn条件下添加CaCO₃对3种基因型冬小麦（远丰998、中育6号、小偃22）幼苗生长及Zn吸收的影响.结果表明,供Zn和添加CaCO₃对小麦幼苗生长量和根冠比均无显著性影响,3种基因型小麦间亦无显著性差异;添加CaCO₃诱发了小麦叶片失绿黄化.无论供Zn还是不供Zn,添加CaCO₃对3种基因型小麦根、茎、叶各部分的Zn含量及累积量均无显著性影响;与不供Zn处理相比,供Zn会大幅度地提高根、茎、叶的Zn含量和累积量,供Zn使3种基因型小麦植株Zn含量分别增加80.0%、104.8%和139.6%,缺Zn敏感型小麦远丰998植株Zn含量和累积量的增加幅度远小于不敏感型小麦中育6号和小偃22.供Zn和添加CaCO₃对小麦幼苗根、茎、叶中P含量均无显著影响,但远丰998小麦根、茎、叶3部分的P含量均明显低于其它两种非敏感型小麦.供Zn使小麦根、茎、叶3部分的P/Zn大幅度降低,添加CaCO₃也使P/Zn呈现降低的趋势.不供Zn条件下添加CaCO₃能诱发小麦失绿黄化,但Zn吸收量未降低.表明在水培条件下,高含量CaCO₃对小麦Zn吸收并未产生明显的抑制作用.     

氯化镉胁迫下葡萄根、叶内源一氧化氮和活性氧的生成

以‘泽香’葡萄扦插苗为试材,在水培条件下,研究了氯化镉(CdCl2)处理下葡萄根系和叶片内源一氧化氮(NO)、活性氧(ROS)的生成规律,以及根系丙二醛(MDA)含量与根系活力的变化.结果表明:在0～1 mmol.L-1范围内,随着CdCl2处理浓度的增加,葡萄扦插苗根系和叶片NO含量、一氧化氮合酶(NOS)活性和根系活力先升高后下降;CdCl2浓度为0.01mmol.L-1时,根系NO含量和NOS活性分别提高51%和63%,超过0.1 mmol.L-1时则显著下降;CdCl2浓度为0.01和0.05 mmol.L-1时,叶片NO含量和NOS活性显著提高.0.5和1.0 mmol.L-1的CdCl2处理显著提高了根系O2.-产生速率、H2O2含量和MDA含量;同浓度CdCl2处理下,叶片中O2.-产生速率明显低于根系O2.-,而H2O2含量明显高于根系.     

P、Zn在小麦细胞内的积累、分布及交互作用的研究

报道了小麦无性系细胞在含有3个P水平(0.5、1.5、3.5mmol·L^-1)和2个Zn水平(0、60μmol·L^-1)的M.S培养液中,细胞对P、Zn的积累、分布特性及交互作用的研究.P和Zn在细胞内的积累分别随外施P、Zn浓 度的提高而提高.与缺Zn比较,加Zn处理能抑制培养7d细胞中P的含量.营养液中0.5～1.5mmol·L^-1 P能促进细胞的含Zn量,但高P处理即抑制细胞的含Zn量.小麦细胞壁固定了细胞83.9%～88.3%的P,而外施P浓度越高,则细胞壁中P分配的比例越大.在供Zn条件下,细胞壁截留了细胞中一半以上的Zn(52.0～60.5%).小麦液泡中P和Zn的含量较少,分别为2.2%～3.8%和10.6%～30%.     

镉胁迫对平邑甜茶脂肪酸构成及脂质过氧化的影响

以平邑甜茶幼苗为试材,研究了镉胁迫下幼苗叶片和根系膜脂肪酸构成、活性氧、脂氧合酶和丙二醛含量的变化.结果表明：氯化镉处理后7～12 h,脂肪酸种类及其相对含量变化最为明显.处理后7 h,叶片和根系脂肪酸不饱和水平升至最高,含量分别达8282%和7243%;叶片可检测到的脂肪酸在处理后12 h由11种增至14种,根系则在处理17 h后由4种增至6种.O₂^.-产生速率在处理3 h、H₂O₂含量在处理7 h时升至最高,丙二醛含量和脂氧合酶活性则随着处理时间的延长逐渐增加.镉胁迫通过诱导活性氧和脂氧合酶来改变平邑甜茶脂肪酸构成,并引起脂质过氧化;镉处理12 h前,脂质过氧化是活性氧和脂氧合酶的共同结果;但处理12 h后,脂质过氧化加剧主要在于脂氧合酶活性的持续增加.     

小麦-蚕豆间作对根系分泌低分子量有机酸的影响

通过盆栽试验收集了不同生育期单作和间作小麦、蚕豆的根系分泌物,用HPLC分析了根系分泌物中低分子量有机酸的含量和种类.结果表明: 小麦-蚕豆间作显著提高了有机酸的分泌量,在小麦分蘖期(57 d)、孕穗期(120 d)和灌浆期(142 d),间作使小麦根系有机酸分泌量分别提高155%、35.6%和92.6%;在蚕豆分枝期(57 d)和籽粒膨大期(142 d),间作使蚕豆根系有机酸分泌量提高87.4%和38.7%.小麦-蚕豆间作改变了根系分泌物中有机酸的种类,与单作小麦相比,在分蘖期,间作小麦根系分泌物中增加了乳酸;在拔节期(98 d),间作小麦根系分泌物中增加了柠檬酸,但未检测到乙酸;在蚕豆分枝期,间作蚕豆根系分泌物中增加了乙酸,但未检测到乳酸;在蚕豆籽粒膨大期,间作蚕豆根系分泌物中增加了乳酸.小麦-蚕豆间作提高了小麦根系有机酸的分泌速率,在小麦孕穗期,间作小麦分泌柠檬酸、富马酸的速率是单作小麦的179和184倍;在小麦灌浆期,间作小麦分泌乳酸的速率是单作的2.53倍.总之,小麦-蚕豆间作增加了有机酸的分泌量,改变了根系分泌物中有机酸的种类,提高了小麦根系有机酸的分泌速率.     

水培硝态氮浓度对冬小麦幼苗氮代谢的影响

以Hoagland营养液为培养基质,以冬小麦为试材,动态测定高(含NO3--N15mmol·L-1)、中(含NO3--N7.5mmol·L-1)、低(含NO3--N2.5mmol·L-1)三种氮水平处理条件下硝态氮的吸收和累积、硝酸还原酶活性、铵态氮含量、小麦吸氮量及根系活力,分析不同供氮水平对冬小麦硝态氮吸收、还原、转运的影响,探讨不同供氮条件下,植物地上、地下部分硝态氮代谢的变化。结果表明:水培条件下,营养液NO3-的消耗量、pH变化、植株全氮以及根系活力均能较好地反映不同氮水平对植株硝态氮代谢的影响;高氮条件下植物体内NO3-进一步同化较中氮弱,冬小麦植株积累了较多的NO3-,而非过多的吸收营养液中的NO3-。不同氮浓度处理下,NO3-的供应与植株NRA间无相关关系,根系与地上部的变化曲线不同;NO3-供应浓度高时,植物地上部是主要同化部位;低浓度时根部是主要同化部位。虽然NO3-是一种安全的氮源,但供应过高则抑制体内硝态氮进一步同化,而供应过低,植物吸收NO3-量不足、根系活力下降,不利于小麦幼苗氮素营养。     

Dry matter production and distribution of zinc in bread and durum wheat genotypes differing in zinc efficiency

Six bread wheat (Triticum aestivum cvs. Kiraç-66, Gerek-79, Aroona, ES 91-12, ES-14 and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes were grown under controlled environmental conditions in nutrient solution for 20 days to study the effect of varied supply of Zn (0 to 1 µM) on Zn deficiency symptoms in shoots, root and shoot dry matter production, and distribution of Zn in roots and shoots.Visual Zn deficiency symptoms, such as whitish-brown lesions on leaves, appeared rapidly and severly in durum wheats, particularly in Kiziltan-91 and Durati. Among the durum wheats, BDMM-19 was less affected by Zn deficiency, and among the bread wheats Kiraç-66, ES 91-12, Aroona and Gerek-79 were less affected than ES-14 and Kirkpinar.Under Zn deficiency, shoot dry matter production was decreased in all genotypes, but more distinctly in durum wheat genotypes. Despite severe decreases in shoot growth, root growth of all genotypes was either not affected or even increased by Zn deficiency. Correspondingly, shoot/root dry weight ratios were lower in Zn-deficient than in Zn-sufficient plants, especially in durum wheat genotypes.The distinct differences among the genotypes in sensitivity to Zn deficiency were closely related with the Zn content (Zn accumulation) per shoot but not with the Zn concentration in the shoot dry matter. On average, genotypes with lesser deficiency symptoms contained about 42% more Zn per shoot than genotypes with severe deficiency symptoms. In contrast to shoots, the Zn content in roots did not differ between genotypes. Shoot/root ratios of total Zn content were therefore greater for genotypes with lesser deficiency symptoms than for genotypes with severe deficiency symptoms (i.e. all durum wheat genotypes).The results suggest that the enhanced capacity of genotypes for Zn uptake and translocation from roots to shoot meristems under deficient Zn supply might be the most important factor contributing to Zn efficiency in wheat genotypes. The results also demonstrate that under severe Zn deficiency, Zn concentration in the shoot dry matter is not a suitable parameter for distinguishing wheat genotypes in their sensitivity to Zn deficiency.     

氮素形态和铁营养对玉米苗期生长及体内铁分布的影响

以玉米(Zea mays)品种‘豫玉-22’为材料,采用营养液培养方法,研究了低铁和正常供铁条件下供应不同形态氮素对玉米苗期生长及体内铁分布的影响。结果表明:(1)与低铁介质相比,常铁介质增加了各氮素处理玉米幼苗的株高、地上部干重、全株干重,降低了根冠比,其中硝态氮处理表现得尤其突出;与供应硝态氮(NO3--N)相比,增施铵态氮(1/2 NO3--N 1/2 NH4 -N,NH4 -N)能明显促进低铁介质中玉米生长,但在常铁介质下作用不明显。(2)相比于低铁介质,正常供铁显著提高了相应处理玉米新叶叶绿素含量及净光合速率;2种供铁介质中,NH4 -N处理的新叶叶绿素含量以及净光合速率均高于其它氮素处理。(3)相比于低铁介质,正常供铁处理总体上增加了玉米各部分活性铁含量和全铁含量,对NO3--N处理的新叶活性铁含量增加尤其明显;2种供铁介质中,NH4 -N均有利于提高新叶活性铁含量和植株地上部全铁含量。(4)玉米新叶活性铁含量不仅与其叶绿素含量显著正相关(r=0.979**),也与叶片净光合速率显著正相关(r=0.950**)。研究发现,供铁状况显著影响玉米新叶的叶绿素含量及其净光合速率且与供氮形态存在互作;供应铵态氮有利于提高缺铁条件下玉米新叶活性铁含量,增强玉米植株的光合能力,进而促进其正常生长。     

Improved nitrogen nutrition enhances root uptake, root-to-shoot translocation and remobilization of zinc ((65) Zn) in wheat

This study focussed on the effect of increasing nitrogen (N) supply on root uptake and root-to-shoot translocation of zinc (Zn) as well as retranslocation of foliar-applied Zn in durum wheat (Triticum durum). Nutrient solution experiments were conducted to examine the root uptake and root-to-shoot translocation of (65) Zn in seedlings precultured with different N supplies. In additional experiments, the effect of varied N nutrition on retranslocation of foliar-applied (65) Zn was tested at both the vegetative and generative stages. When N supply was increased, the (65) Zn uptake by roots was enhanced by up to threefold and the (65) Zn translocation from roots to shoots increased by up to eightfold, while plant growth was affected to a much smaller degree. Retranslocation of (65) Zn from old into young leaves and from flag leaves to grains also showed marked positive responses to increasing N supply. The results demonstrate that the N-nutritional status of wheat affects major steps in the route of Zn from the growth medium to the grain, including its uptake, xylem transport and remobilization via phloem. Thus, N is a critical player in the uptake and accumulation of Zn in plants, which deserves special attention in biofortification of food crops with Zn.     

Factors affecting formation of cluster roots in Myrica gale seedlings in water culture

The effect of nutrient deficiency, aeration, phosphorus supply, and nitrogen source on the formation of cluster (proteoid) roots was examined in Myrica gale seedlings growing in water culture. Only the omission of phosphorus resulted in the formation of significant numbers to cluster roots when plants were grown in a number of 1/4 strength Hoagland's solutions, each lacking one mineral nutrient. Aeration shortened the time required for cluster root formation and increased the percentage of plants forming cluster roots. The proportion of the root system comprised of cluster roots decreased as the phosphorus concentration in the solution increased and no cluster roots formed in solutions containing 8 mg P/L. Phosphorus supply also affected total plant biomass, proportion of biomass comprising nitrogen-fixing nodules, shoot:root ratio, phosphorus concentration in the leaves and phosphorus content of the plants. The plants showed luxury consumption of phosphorus and were able to produce large amounts of biomass utilizing only stored phosphorus.Nitrogen source also affected cluster root formation. Urea-fed plants produced cluster roots more quickly and devoted a substantially larger proportion of root growth to cluster roots than did nitrate-fed plants. The longest cluster root axes were produced in nitrate-fed plants supplied with no phosphorus and the shortest were in urea-fed plants at 4 mg P L^–1.Four methods for expressing the extent of cluster root formation were examined and it was concluded that cluster roots as a proportion of total fine root dry weight is preferable in many cases. Formation of cluster roots in response to phosphorus deficiency coupled with previously demonstrated traits allows Myrica gale to adapt to a wide range of soil conditions.     

Alleviation of Zn toxicity by low water availability

Heavy metal contamination and drought are expected to increase in large areas worldwide. However, their combined effect on plant performance has been scantly analyzed. This study examines the effect of Zn supply at different water availabilities on morpho‐physiological traits of Quercus suber L. in order to analyze the combined effects of both stresses. Seedlings were treated with four levels of zinc from 3 to 150 µM and exposed to low watering (LW) or high watering (HW) frequency in hydroponic culture, using a growth chamber. Under both watering regimes, Zn concentration in leaves and roots increased with Zn increment in nutrient solution. Nevertheless, at the highest Zn doses, Zn tissue concentrations were almost twice in HW than in LW seedlings. Functional traits as leaf photosynthetic rate and root hydraulic conductivity, and morphological traits as root length and root biomass decreased significantly in response to Zn supply. Auxin levels increased with Zn concentrations, suggesting the involvement of this phytohormone in the seedling response to this element. LW seedlings exposed to 150 µM Zn showed higher root length and root biomass than HW seedlings exposed to the same Zn dose. Our results suggest that low water availability could mitigate Zn toxicity by limiting internal accumulation. Morphological traits involved in the response to both stresses probably contributed to this response.     

Effect of zinc nutrition on salinity-induced oxidative damages in wheat genotypes differing in zinc deficiency tolerance

Zinc deficiency and salinity are well-documented soil problems and often occur simultaneously in cultivated soils. Usually, plants respond to environmental stress factors by activating their antioxidative defense mechanisms. The antioxidative response of wheat genotypes to salinity in relation to Zn nutrition is not well understood. So, we investigated the effect of Zn nutrition on the growth, membrane permeability and sulfhydryl group (–SH groups) content of root cells and antioxidative defense mechanisms of wheat plants exposed to salt stress. In a hydroponic experiment, three bread wheat genotypes (Triticum aestivum L. cvs. Rushan, Kavir, and Cross) with different Zn-deficiency tolerance were exposed to adequate (1 μM Zn) and deficient (no Zn) Zn supply and three salinity levels (0, 60, and 120 mM NaCl). The results obtained showed that adequate Zn nutrition counteracted the detrimental effect of 60 mM NaCl level on the growth of all three wheat genotypes while it had no effect on the root and shoot growth of ‘Rushan’ and ‘Kavir’ at the 120 mM NaCl treatment. At the 0 and 60 mM NaCl treatments, Zn application decreased root membrane permeability while increased –SH group content and root activity of catalase (CAT) and superoxide dismutase (SOD) in ‘Rushan’ and ‘Kavir’. In contrast, Zn had no effect on the root membrane permeability and –SH group content of ‘Rushan’ and ‘Kavir’ exposed to the 120 mM NaCl treatment. At all salinity levels, ‘Cross’ plants supplied with Zn had lower root membrane permeability and higher –SH group content compared to those grown under Zn-deficient conditions. At the 0 and 60 salinity levels, Zn-deficient roots of Kavir and Rushan genotype leaked significantly higher amounts of Fe and K than the Zn-sufficient roots. In contrast, at the 120 mM treatment, Zn application had no effect or slightly increased Fe and K concentration in the root ion leakage of these wheat genotypes. For ‘Cross’, at all salinity levels, Zn-deficient roots leaked significantly higher amounts of Fe and K compared with the Zn-sufficient roots. The differential tolerance to salt stress among wheat genotypes examined in this study was related to their tolerance to Zn-deficiency, –SH group content, and root activity of CAT and SOD. Greater tolerance to salinity of Zn-deficiency tolerant genotype ‘Cross’ is probably associated with its greater antioxidative defense capacity.     

缺磷胁迫对小麦根细胞周期蛋白基因cyc1At表达的影响

用液培方法研究了缺磷胁迫对小麦(TriticumaestivumL.)根系生长的影响。结果表明,随着介质磷水平的提高,小麦根轴长度和植株生长素浓度均降低。在低磷条件下用生长素极性运输抑制剂三碘苯甲酸(TIBA)处理后,小麦的根轴长度明显降低,表明生长素参与了缺磷小麦根轴生长的调控。缺磷小麦根部生长素浓度的提高诱导了细胞周期蛋白基因cyclAt的表达,促进了根分生组织细胞的分裂并驱动了根的生长。     

Root Respiration and Carbohydrate Status of Two Wheat Genotypes in Response to Hypoxia

To investigate root respiration and carbohydrate status in relationto waterlogging or hypoxia tolerance, root respiration rateand concentrations of soluble sugars in leaves and roots weredetermined for two wheat (Triticum aestivum L.) genotypes differingin waterlogging-tolerance under hypoxia (5% O₂) and subsequentresumption of full aeration. Root and shoot growth were reducedby hypoxia to a larger extent for waterlogging-sensitive Coker9835. Root respiration or oxygen consumption rate declined withhypoxia, but recovered after 7 d of resumption of aeration.Respiration rate was greater for sensitive Coker 9835 than fortolerant Jackson within 8 d after hypoxia. The concentrationsof sucrose, glucose and fructose decreased in leaves for bothgenotypes under hypoxia. The concentration of these sugars inroots, however, increased under hypoxia, to a greater degreefor Jackson. An increase in the ratio of root sugar concentrationto shoot sugar concentration was found for Jackson under hypoxicconditions, suggesting that a large amount of carbohydrate waspartitioned to roots under hypoxia. The results indicated thatroot carbohydrate supply was not a limiting factor for rootgrowth and respiration under hypoxia. Plant tolerance to waterloggingof hypoxia appeared to be associated with low root respirationor oxygen consumption rate and high sugar accumulation underhypoxic conditions.Copyright 1995, 1999 Academic Press Oxygen consumption rate, sugar accumulation, Triticum aestivum L., waterlogging tolerance     

稻、麦根系H~ 的分泌与介质磷水平的关系

水稻、小麦根系H~ 的分泌量随供磷水平的降低而增加,并存在明显的昼夜变化。在自然光照下H~ 分泌量随光强度增加而增多,同时强光比黑暗时H~ 分泌对磷供应水平更为敏感。磷供应不足还诱导水稻根系柠檬酸分泌量增加,而苹果酸则差异不明显。难溶性磷的溶解率与根系H~ 和柠檬酸分泌所导致的根际pH下降有密切联系。因此,在有效磷不足的条件下可明显提高稻、麦根际土壤中难溶性磷的利用率,其中丰产型小麦和粳稻品种对土壤中磷利用的根际效应更为显著。