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1.
Amanda Black Ronald George McLaren Thomas Wilson Speir Lynne Clucas Leo Murtagh Condron 《Biology and Fertility of Soils》2014,50(4):685-694
The aim of this research was to identify and quantify gaps in currents methods and models for predicting the plant availability of selected nutrient and contaminant metals (Cu, Ni, Zn, Cd) in soil. This study investigated relationships between the relative solubility of Cu, Ni, Zn, and Cd determined by six extraction methods with short-term uptake by shoots and roots of wheat (Triticum aestivum). For Cu, Ni, and Cd, relationships between solubility and plant uptake were found to be different for shoots and roots, with Cu and Ni solubility being more closely correlated with root uptake compared with shoot uptake. Correlation coefficients for Cd concentrations in shoot and root tissue for all six solubility methods were poor (r 2?<?0.5), while corresponding results for Zn explained more than 50 % of shoot variation but less than 50 % of root variation. Soil Cu solubility explained up to 85 % of variation in root uptake compared with 42–55 % for shoot uptake. These results clearly demonstrated that purely chemical and passive diffusion mechanisms were inadequate predictors of Cd uptake by shoots and roots, together with Cu uptake by shoots. Thus further attempts at refining soil metal bioavailability assays based solely on chemical extraction without consideration of plant responses are unlikely to improve prediction of plant uptake. 相似文献
2.
Gezahegn Girma Melaku Gedil Charles Spillane 《Genetic Resources and Crop Evolution》2017,64(2):291-305
The high cost and supply shortage of seed yam propagules for planting are major constraints in yam production. In the water yam (Dioscorea alata L.), aerial tubers have potential as alternative sources of planting material. In this study, we investigated morphological, molecular and ploidy variation across multiple aerial tuber producing accessions of Dioscorea alata. Initial screening of over 800 accessions from the International Institute of Tropical Agriculture germplasm collection for aerial tuber production identified a subset (15 %) of accessions, which produced aerial tubers. The aerial tuber producing accessions (along with 18 non-aerial tuber accessions) were further characterized for phenotypic and ploidy variation. In addition, using SSR markers we characterized the genetic diversity amongst all of the aerial tuber producing accessions, along with six non-aerial tuber producing accessions. Multiple Correspondence Analysis (MCA) using morphological data grouped the accessions according to their aerial tuber production. The aerial tuber production characteristics of accessions were associated with phenotypic variables and ploidy levels. The MCA analysis revealed three main groups consisting of; Group 1) all non aerial tuber producing accessions (n = 15), hastate leaf shape, less or no anthocyanin pigmentation and diploid (2n = 2x = 40), Group 2) group with some aerial tuber producing accessions, different extent of anthocyanin pigmentation, sagittate leaf shape, mainly diploid (n = 44) and three triploid (2n = 3x = 60) and 3) a group where all individuals bear aerial tuber, cordate leaf shape, intermediate anthocyanin pigmentation and majority (n = 74) tetraploid (2n = 4x = 80) and three triploid individuals. Aerial tuber production may be subject to a genome dosage effect as an increase in aerial tuber production was associated with increased ploidy level. For instance, tetraploid plants produce more aerial tubers per sprout than either triploids or diploids. Principal coordinate analysis based on SSR markers using Jaccard’s coefficient also revealed distinct groups associated with the pattern of aerial tuber formation, leaf shape and anthocyanin pigmentation. Overall our study indicates the usefulness of combining SSR markers, ploidy level and phenotypic data for identification and classification of Dioscorea alata accessions according to their extent of aerial tuber production. 相似文献
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4.
The mechanisms of low cadmium (Cd) accumulation in sweet potato cultivars are obscure. In this study, seedlings of a low-Cd (Nan88, N88) and a high-Cd cultivar (Xiang 16, X16) were grown in Hoagland’s solution containing Cd concentrations of 0 (control), 1 (Cd1), and 10 µM (Cd10) for 20 days. We analyzed the Cd accumulation, root morphology and low molecular weight organic acids (LMWOAs) excreted by the root tips (RTs). The total root length (RL) and specific root length (SRL) in X16 were greater than those in N88 following Cd treatments. In the Cd1 treatment, RL and surface area for root diameter was ≤0.2 mm, and RTs in X16 were also greater than those in N88. LMWOAs excreted from the RTs initially increased and then decreased as Cd concentration increased. The RTs of N88 were more efficient at excreting organic acids than were those of X16. The low-Cd cultivar with lower RL and SRL displayed greater ability to excrete organic acids in Cd treatments, which can decrease Cd translocation from roots to shoots. Furthermore, root morphology and some LMWOAs released from the root tips played an important role in the differing rates of Cd accumulation in the two sweet potato cultivars. 相似文献
5.
《Soil Science and Plant Nutrition》2013,59(3):278-285
Abstract The effects of exogenous NaCl and silicon on ion distribution were investigated in two alfalfa (Medicago sativa. L.) cultivars: the high salt tolerant Zhongmu No. 1 and the low salt tolerant Defor. The cultivars were grown in a hydroponic system with a control (that had neither NaCl nor Si added), a Si treatment (1 mmol L?1 Si), a NaCl treatment (120 mmol L?1 NaCl), and a Si and NaCl treatment (120 mmol L?1 NaCl + 1 mmol L?1 Si). After 15 days of the NaCl and Si treatments, four plants of the cultivars were removed and divided into root, shoot and leaf parts for Na+, K+, Ca2+, Mg2+, Fe3+, Mn2+, Cu2+ and Zn2+ content measurements. Compared with the NaCl treatment, the added Si significantly decreased Na+ content in the roots, but notably increased K+ contents in the shoots and leaves of the high salt tolerant Zhongmu No.1 cultivar. Applying Si to both cultivars under NaCl stress did not significantly affect the Fe3+, Mg2+ and Zn2+ contents in the roots, shoots and leaves of Defor and the roots and shoots of Zhongmu No.1, but increased the Ca2+ content in the roots of Zhongmu No.1 and the Mn2+ contents in the shoots and leaves of both cultivars, while it decreased the Ca2+ and Cu2+ contents of the shoots and leaves of both cultivars under salt stress. Salt stress decreased the K+, Ca2+, Mg2+ and Cu2+ contents in plants, but significantly increased Zn2+ content in the roots, shoots and leaves and Mn2+ content in the shoots of both cultivars when Si was not applied. Thus, salt affects not only the macronutrient distribution but also the micronutrient distribution in alfalfa plants, while silicon could alter the distributions of Na+ and some trophic ions in the roots, shoots and leaves of plants to improve the salt tolerance. 相似文献
6.
Hossein Mozafari Zahra Asrar Mohammad Mehdi Yaghoobi Hassan Salari Mohammad Mozafari 《Journal of plant nutrition》2016,39(5):628-642
This study was carried out to evaluation of some nutrients accumulation including Ni (nickel), Fe (iron), Mg (magnesium), Cu (copper), Ca (calcium) as well as Ni translocation factor (TF) in three tomato cultivars grown hydroponically under treatments including L-histidine (His) and calcium chloride (CaCl2) (300 µM) exposed to nickel (II) sulfate (NiSO4) (150 and 300 µM) by ICP-OES (inductively coupled plasma atomic emission spectroscopy) analysis. Tomato cultivars included Cal-J N3, Early Urbana Y and. Results indicated that shoot Ni accumulation increased under Ni stress. Ca and His reduced root, shoot Ni content and Ni TF (translocation factor) under Ni stress in Petoearly CH cultivar. Ni stress also decreased root and shoot Ca, Fe, Mg and Cu while Ca and His improved the nutrients uptake, and inhibited Ni accumulation. Therefore, Ca and His alleviated adverse effects of Ni stress on nutrients in Petoearly CH cultivar. Beside, Ca and His interaction alleviate Ni stress by inhibition of Ni uptake and translocation as well as plant nutrition improvement in the tomato plants. 相似文献
7.
J. Obidiegwu E. Rodriguez E. Ene-Obong J. Loureiro C. Muoneke C. Santos M. Kolesnikova-Allen R. Asiedu 《Genetic Resources and Crop Evolution》2010,57(3):351-356
Dioscorea alata L. is a highly important crop, widely distributed in the humid and semi-humid tropics. Flow cytometry was used to determine the ploidy levels of 74 D. alata genotypes collected mainly from West African countries. Sixty three of the genotypes were found to be tetraploid, one was hexaploid and ten were octoploid. The high percentage of tetraploids together with the small percentage of hexaploid individuals and the absence of diploid individuals gives us some more clues on the possible origin of these species. No association between ploidy level and place of cultivation was found for the tested material. The obtained results represent important knowledge for enhancing the breeding methodologies and optimize germplasm management of this species. It also offers further insights to the phylogeny and evolution of Dioscorea species. 相似文献
8.
Phenylalanine ammonia-lyase activity (PAL, EC 4.3.1.5), total phenolics, soluble proteins, malondialdehyde and metals accumulation in four-week old chamomile (Matricaria chamomilla) plants cultivated in nutrient solution and exposed to low (3 μM) and high (60 and 120 μM) levels of cadmium (Cd) or copper (Cu) for 7 days were studied. High Cd concentrations had a stimulatory effect on PAL activity and soluble phenolics accumulation while high Cu doses decreased soluble proteins in the leaf rosettes. In the roots, extreme stimulatory effects of 60 and 120 μM Cu were observed on PAL activity, phenolics and malondialdehyde accumulation, while protein content was reduced by these Cu doses. Cd accumulation was higher in the leaf rosettes compared to copper, but the opposite was recorded in the roots. Taken together, the stimulatory effect of Cu on phenolic metabolism was recorded, even though high malondialdehyde accumulation may be an indication that phenolics was not sufficient to counteract reactive oxygen species formation thus leading to damage of membrane integrity. In comparison to Cd, Cu had more noticeable effect on the parameters studied to support its strong redox-active properties. These facts in correlation to antioxidative properties of phenolic metabolites are also discussed. 相似文献
9.
This study was designed to determine and compare root growth and nutritional responses of creeping bentgrass cultivars that differ in heat tolerance to differential, supraoptimal, shoot and root temperatures. Shoots and roots of ‘Penncross’ (heat sensitive) and ‘L‐93’ (heat tolerant) were exposed to four air/soil temperature regimes (20/20°C‐control, 20/35°C, 35/20°C, and 35/35°C) in water baths and growth chambers. Exposing roots to supraoptimal root temperature (35°C) while maintaining shoots at normal temperature (20°C) or particularly at 35°C reduced root fresh weight, root number, and contents of nitrogen (N), phosphorus (P), and potassium (K) in shoots and roots and accelerated root death for both cultivars. High root temperature had greater detrimental effects on root growth and nutrient element accumulation than high shoot temperature for both cultivars. A low root temperature at supraoptimal shoot temperature improved root growth, reduced root mortality; and increased N, P, and K contents in shoots and roots. Among the three nutrient elements, K was the most sensitive to changes in root temperature. L‐93 generally maintained higher fresh weight and number of roots and higher N, P, and K contents in shoots and roots, particularly K in roots, under high root (20/35°C) or shoot/root (35/35°C) temperatures. The results indicated that root growth and nutrient element accumulation, particularly of K, played an important role in creeping bentgrass tolerance to heat stress imposed on shoots by high air temperature or to roots by high soil temperatures. The enhanced root growth and nutrient element relations with a low root temperature at supraoptimal ambient temperatures could lead to the improved shoot growth in cool‐season grasses observed under these conditions. 相似文献
10.
Sedigheh Safarzadeh Abdolmajid Ronaghi Najafali Karimian 《Archives of Agronomy and Soil Science》2013,59(2):231-245
Heavy metal uptake, translocation and partitioning differ greatly among plant cultivars and plant parts. A pot experiment was conducted to determine the effect of cadmium (Cd) levels (0, 45 and 90 mg kg?1 soil) on dry matter yield, and concentration, uptake and translocation of Cd, Fe, Zn, Mn and Cu in seven rice cultivars. Application of 45 mg Cd kg?1 soil decreased root and shoot dry weight. On average, shoot and root Cd concentrations and uptake increased in all cultivars, but micronutrients uptake decreased following the application of 45 mg Cd kg?1. No significant differences were observed between 45 and 90 mg kg?1 Cd levels. On average, Cd treatments resulted in a decrease in Zn, Fe and Mn concentrations in shoots and Zn, Cu and Mn concentrations in roots. Differences were observed in Cd and micronutrient concentrations and uptake among rice cultivars. Translocation factor, defined as the shoot/root concentration ratio indicated that Cu and Fe contents in roots were higher than in shoots. The Mn concentration was much higher in shoots. Zinc concentrations were almost similar in the two organs of rice at 0 and 45 mg Cd kg?1. A higher Cd level, however, led to a decrease in the Zn concentration in shoots. 相似文献
11.
用土培试验研究了青菜的两个品种火青菜(Cu耐性品种)和四月慢(Cu敏感性品种)在重金属CuZn胁迫下的响应差异。结果表明不论是单Cu、单Zn处理还是CuZn复合处理,两个青菜品种的生物量、含水量和重金属含量均因所处理重金属浓度和品种的不同而表现出差异;对地上部含糖量的分析发现,Cu耐性品种火青菜积累可溶性糖的能力显著大于Cu敏感性品种四月慢积累可溶性糖的能力。CuZn复合处理较单一处理均增加两种青菜根中CuZn的积累,但对于地上部来说,CuZn处理浓度不同,青菜品种不同,其影响存在差异。 相似文献
12.
Immobilization of metals by two materials (zeolite, AZ, and a synthetic, carbonate-rich material, “slovakite”, SL) was tested in a pot experiment with two soils from urban areas of Sevilla and two soils affected by a mine spill. Barley (Hordeum vulgare L. Hispanic) was grown in the pots, and metal contents were measured after 31 days in shoots and roots. Available metal was estimated by extraction with CaCl2 (readily soluble), ethylenediaminetetraacetic acid (EDTA; plant available), a mixture of organic acids (soluble by root exudates), and glycine (bioaccessible by ingestion). Neither treatment caused significant differences on plant growth or metal contents of shoots, whereas roots contained more Cu in the SL treatments. Root Zn uptake was reduced in all cases, but reduction of Pb in roots was observed only in AZ treatments of the mine-spill soils. The effects on metal availability were often method-dependent. Decrease of CaCl2 data were observed only in the mine-spill soils. EDTA-soluble metals were clearly decreased by both materials. Bioaccessible Zn were decreased by either material in several cases (but not in the most heavily polluted soil), whereas Cu or Pb data were less conclusive. 相似文献
13.
A. K. Phurailatpam K. A. Geetha Satyabrata Maiti 《Genetic Resources and Crop Evolution》2018,65(6):1565-1570
Piper betle L. (betelvine) is a dioecious species which is a native of Central and South East Asia and it is cultivated in an area of about 50,000 ha in India. The basic chromosome number of this species is x?=?13. Only fragmented work has so far been reported on chromosome numbers and ploidy status. The extremely small size and high number of chromosomes, interclonal variability and very dense cytoplasmic contents make critical analysis difficult. In India, a large number of germplasm has been collected and assembled in All India Co-ordinated Research Project on Betelvine centers by sustained efforts of betelvine workers over a period of two and half decades. Hybridization work was also initiated and a few hybrids have been developed in India. But hybrid depression was noticed in most of the hybrids. Hence a study was undertaken to determine compatible ploidy level of available male and female germplasm using flow cytometry. Cytological studies conducted in a selected male cultivar revealed 2n?=?3x?=?39 and female cultivar it was 2n?=?4x?=?52 chromosomes and these cultivars were used as control samples in the flow cytometry analysis. Flow cytometric study showed that all male accessions were grouped within the same ploidy level (triploid) while all females were grouped in another ploidy group (tetraploid). The present study also gave explanation for the observed hybrid depression due to the possibility of aneuploid hybrid formation by the fusion of unbalanced gametes developed from the triploid male parents. Flow cytometry could thus be utilized for the rapid screening and earlier detection of the aneuploids in hybrid seedlings in the species. Separation of sexes by ploidy difference is also a new report in P. betle. 相似文献
14.
高铝低磷胁迫对胡枝子生长及矿质元素吸收的影响 总被引：1，自引：0，他引：1
限制酸性土壤作物生长的最重要、最普遍的因子是Al3+ 的毒害和 P 的缺乏.本文用溶液培养试验研究两种不同生态型的二色胡枝子在高Al低P胁迫下的矿质营养元素积累情况.试验表明,江西胡枝子比河北胡枝子更耐低 P 低 pH 的生长环境,但两者间耐Al性无显著差异;100 μm/L Al 处理显著地抑制了两种胡枝子对 Ca 的吸收,降低了根系 Mg 的积累量,对植株的 K、P、Fe、Zn、Cu 含量没有显著影响;低 P 处理没有显著降低两种胡枝子对 Ca、K、Fe、Zn、Cu 和江西胡枝子对 Mg 的吸收,但是低 P 处理显著降低了河北胡枝子对 Mg 的吸收和转运.二色胡枝子植株吸收的 Al 主要积累在根部,地上部分Al含量仅是根系的1% 左右. 相似文献
15.
Stan Cox Pheonah Nabukalu Andrew H. Paterson Wenqian Kong Susan Auckland Lisa Rainville Sheila Cox Shuwen Wang 《Genetic Resources and Crop Evolution》2018,65(2):387-390
A perennial version of grain sorghum [S. bicolor (L.) Moench] would create opportunities for greatly reducing tillage and preventing soil degradation. Efforts to select for perenniality and grain production among progeny of hybrids between S. bicolor (2n = 20) and the weedy tetraploid perennial S. halepense (L.) Pers. (2n = 40) are complicated in that F1 hybrids produced by diploid × tetraploid sorghum crosses are usually tetraploid. In 2013, a set of random pollinations between 19 diploid cytoplasmic male-sterile inbred lines and 43 tetraploid perennial plants produced 165 F1 hybrid plants, more than 75% of which had highly atypical plant, panicle, and seed phenotypes. Phenotypic segregation in F2 populations derived from atypical hybrids was also anomalous. Examination of mitotic metaphase cells in F1 or F2 root tips revealed that 129 of the 165 hybrids were diploid. Parentage of the diploid progenies was confirmed using simple-sequence repeat analysis. The mechanism by which diploid hybrids arise from diploid × tetraploid crosses is unknown, but it may involve either production of monohaploid (n = 10) pollen by the tetraploid parent or chromosome elimination during early cell divisions following formation of the triploid zygote. The ability to produce diploid germplasm segregating for S. bicolor and S. halepense alleles could have great utility, both for the development of perennial sorghum and for the improvement of conventional grain sorghum. 相似文献
16.
C. D. Foy 《Journal of plant nutrition》2013,36(10-11):1361-1380
Abstract Barley, Hordeum vulgare L., is extremely sensitive to excess soluble or exchangeable aluminum (Al) in acid soils having pH values below about 5.5. Aluminum tolerant cultivars are needed for use in rotations with potatoes which require a soil pH below 5.5 for control of scab disease. They are also potentially useful in the currently popular “low input, sustainable agriculture (LISA)”; in which liming even the plow layer of soil is not always possible or cost effective, or in situations where surface soils are limed but subsoils are acidic and Al toxic to roots. Ten barley cultivars were screened for Al tolerance by growing them for 25 days in greenhouse pots of acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic, typic Hapludult) treated with either 750 or 4000 μg?g‐1 CaCO3 to produce final soil pH values of 4.4 and 5.7, respectively. Based on relative shoot dry weight (weight at pH 4.4/weight at pH 5.7 X 100), Tennessee Winter 52, Volla (England), Dayton and Herta (Denmark) were significantly more tolerant to the acid soil than Herta (Hungary), Kearney, Nebar, Dicktoo, Kenbar and Dundy cultivars. Relative shoot dry weights averaged 28.6% for tolerant and 14.1% for sensitive cultivar groups. Comparable relative root dry weights were 41.7% and 13.7% for tolerant and sensitive cultivars, respectively. At pH 4.4, Al concentrations were nearly three times as high in shoots of sensitive cultivars as in those of the tolerant group (646 vs. 175 μg?g‐1), but these differences were reduced or absent at pH 5.7. At pH 4.4, acid soil sensitive cultivars also accumulated phosphorus concentrations that were twice as high as those in tolerant cultivars (1.2% vs. 0.64%). At pH 5.7, these P differences were equalized at about 0.7% for both tolerant and sensitive groups. At pH 4.4, shoots of the Al‐sensitive cultivar Nebar contained 1067 μg?g‐1 Al and 1.5% P. Concentrations of Al and P in the shoots of acid soil sensitive cultivars grown at pH 4.4 exceeded levels reported to produce toxicity in barley. The observed accumulation of such concentrations of Al and P in the shoots of plants grown under Al stress is unusual and deserves further study. 相似文献
17.
J. Martínez-Calvo M. Naval E. Zuriaga G. Llácer M. L. Badenes 《Genetic Resources and Crop Evolution》2013,60(1):233-241
Diospyros kaki Thunb. originated in Eastern Asia, as evidenced of its culture in China as early as several centuries B.C. In the seventh century, persimmon was introduced to Japan and later, in the fourteenth century to Korea. There is no information about persimmon culture in Europe until the seventeenth century, with the spread over the world occurring in the eighteenth century. The genus Diospyros contains more than 400 species, with levels of ploidy ranging from diploid (2n = 2x = 30) up to nonaploid (2n = 9x = 135). The primary economic crop species is Diospyros kaki Thunb., which is mainly hexaploid (2n = 6x = 90) and includes hundreds of cultivars. Although a relatively recent introduction in Europe, the species has adapted well, and the genetic diversity have been expanded with culture and selection for the past 200 years in the Mediterranean basin. These locally adapted cultivars were evaluated with cultivars from Asian origin in a germplasm collection established at IVIA in Valencia, Spain. In this paper 27 cultivars from the IVIA collection were studied by multivariate analysis, and 37 variables were analyzed using a Principal Components Analysis and cluster analysis following the method UPGMA. Studies on correlations and significance among variables identified the most relevant ones, and thus provided information for a future core collection. 相似文献
18.
Wellington Ronildo Clarindo Carlos Roberto Carvalho Eveline Teixeira Caixeta Andréa Dias Koehler 《Genetic Resources and Crop Evolution》2013,60(8):2253-2259
The supposedly first plant of the coffee cultivar “Híbrido de Timor” (HT) was found in 1927, being denoted as HT CIFC 4106. According to different researchers, this plant originated from a natural interspecific hybridation between Coffea arabica (4x = 44) and Coffea canephora (2x = 22). From HT CIFC 4106, other HT accessions were obtained and employed to establish germplasm banks in some countries. As HT has been widely used in Coffea breeding programs, this study aimed to characterize different HT accessions with regard to ploidy, nuclear DNA content and base composition. Based on these data, the ploidy of HT CIFC 4106 was determined, suggesting that this accession is an allotriploid formed from reduced reproductive cell of C. canephora and of C. arabica. All HT CIFC 4106 plants exhibited the same 2C-value, AT% and chromosome number, showing that vegetative propagation has enabled the multiplication and germplasm conservation of this cytotype since 1927. Further five analyzed HT accessions showed distinct nuclear 2C-value and AT%. Since HT CIFC 4106 has been considered the first HT, it is suggested that aneuploid reproductive cells of this HT originated the other plants. Considering that HT accessions are used in the development of C. arabica cultivars, the findings of this study are important for the design of strategies to obtain new cultivars for breeding programs. Moreover, these data represent the first step to understand the origin and genome evolution of the HT. 相似文献
19.
Gao Li-Li Wang Sheng-Feng Liu Zi-Fei Huang Jin-Sheng Hilman Liu Rong-Le 《Journal of plant nutrition》2016,39(7):1016-1025
The objectives were to determine whether two peanut cultivars show different tolerance to calcium (Ca) deficiency. The seedlings of cultivars LH11 and YZ9102 at first trifoliate leaf stage were transplanted in nutrient solution for 28 days with 0.01 and 2.0 mmol/L Ca treatments. Low Ca supply did not affect plant growth, root length and surface area of YZ9102, whereas decreased plant biomass, root length and surface area of LH11 seedlings that appeared necrosis in shoot tip. YZ9102 plant had higher Ca concentration and more Ca distribution to leaves than LH11. Under limited Ca condition, LH11 appeared net Ca2+ effluxes in the zones of 0.2 ～ 1.5 mm from root apex, while YZ9102 roots maintained net Ca2+ influxes. Peanut cultivar YZ9102 seedlings had longer roots and higher capacities of Ca uptake and Ca translocation to shoots than LH11, which might be account for higher tolerance to Ca deficiency compared with LH11. 相似文献
20.
J. Cambraia J.A. Pimenta M.M. Estevão R. Sant'Anna 《Journal of plant nutrition》2013,36(12):1435-1445
The effects of Al on nitrate uptake and on the activity of the nitrate reductase (NR) in two hybrid cultivars of sorghum (Sorghum bicolor (L.) Moench) differing in Al tolerance were studied. The nitrate uptake by intact root system was strongly reduced by Al in both cultivars, but mainly in the Al‐sensitive cultivar. The kinetic constants also changed in the presence of Al: Vmax decreased 98% and 71% and Km increased 267% and 42% in the Al‐sensitive and Al‐tolerant cultivar, respectively. Aluminum reduced the in vitro NR activity on the roots and shoots of both cultivars, especially of the Al‐sensitive cultivar. Aluminum added to the nutrient solution or to the reaction mixture, however, inhibited differentially the NR of the roots and shoots, indicating marked differences between the enzymes from these two tissues. Aluminum reduced the Vmax but did not affect the Km of nitrate activation of the shoot NR. Therefore, Al inhibition of the NR was non‐competitive and could not be reversed by increasing nitrate concentration. Aluminum not only reduced the nitrate uptake but also had a direct effect on the NR and consequently on nitrate reduction. A correlation between NR tolerance to Al and plant tolerance to Al was observed. 相似文献