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1.
Wheat cultivars differ widely in manganese (Mn) efficiency. To investigate the reasons for different Mn efficiencies, a pot experiment with soil, a solution‐culture experiment, and model calculations were carried out. The pot experiment was conducted with wheat (Triticum aestivum L. cvs. PBW 373, PBW 154, PBW 343, PBW 138, and Triticum durum L. cvs. PBW 34 and PDW 233) grown in a screen house in India. The soil was a loamy sand with pH 8.1, DTPA‐extractable Mn 1.62 mg (kg soil)–1, and initial soil solution Mn concentration (CLi) of 0.19 μM. When fertilized with 50 mg Mn (kg soil)–1, CLi increased to 0.32 μM. At CLi 0.19 μM, wheat cv. PBW 373 produced 74% of its maximum shoot dry weight (SDW) with 64% of its maximum root length (RL), while cv. PDW 233 produced only 25% of its maximum SDW with 11% of its maximum RL. The other wheat cultivars were between these extremes. Manganese deficiency caused a reduction in shoot growth, but more strongly reduced root growth. The low Mn efficiency of T. durum cv. PDW 233 was related to a strong depression of its root growth. Manganese influx was similar for all cultivars. In solution culture below 1 μM Mn, under controlled climate‐chamber conditions, Mn influx was linearly related to Mn concentration. Both the efficient cv. PBW 343 and the inefficient cv. PDW 233 had a similar influx. Uptake kinetic parameters from the solution experiment together with soil and plant parameters from the pot experiment were used in a mechanistic nutrient‐uptake model. Calculated values of Mn influx for wheat grown in soil were 55% to 74% of measured values. A sensitivity analysis showed that increasing CLi or the slope of the uptake isotherm by about 30% would be enough to reach the observed influx. The results of this research indicate that an increase of Mn solubility by microbial or chemical mobilization would increase Mn uptake. But on the other hand, no chemical mobilization would be required to increase Mn uptake if the plant improved its uptake kinetics. Low Mn efficiency of some wheat cultivars was related to their reduced root growth at low soil Mn supply.  相似文献   

2.
Poor zinc (Zn) nutrition of wheat is one of the main causes of poor human health in developing countries. A field experiment with no zinc and foliar zinc application (0.5% ZnSO4.7H2O) on bread wheat (8), durum wheat (3), and triticale (4) cultivars was conducted in a randomized block design with three replications in 2 years. The experimental soil texture was loamy sand with slightly alkalinity. The grain yields of bread wheat, triticale, and durum wheat cultivars increased from 43.6 to 56.4, 46.5 to 51.6, and 49.4 to 53.5 t ha?1, respectively, with foliar application of 0.5% ZnSO4.7H2O. The highest grain yield was recorded by PBW 550 (wheat), TL 2942 (triticale), and PDW 291 (durum), which was 5.22, 4.24, and 4.56% and significantly higher over no zinc. Foliar zinc application increased zinc in bread wheat, triticale, and durum wheat cultivars grains varying from 31.0 to 63.0, 29.3 to 61.8, and 30.2 to 62.4?mg kg?1, respectively. So, agronomic biofortification is the best way which enriching the wheat grains with zinc for human consumption.  相似文献   

3.
《Journal of plant nutrition》2013,36(12):2677-2688
ABSTRACT

Under field conditions, wheat cultivar PBW 343 produced 1.5 times higher grain yield than PDW 233, when grown on low manganese (Mn) soil. To explain the differences in Mn efficiency a pot experiment was conducted using Mn deficient Typic ustochrept loamy sand soil treated with 0, 50, and 100?mg?Mn?kg?1 soil. In no-Mn treatment, both the wheat cultivars showed Mn deficiency symptoms and cultivar PBW 343 produced 30% of the maximum dry matter yield (DMY) attained at high Mn supply, while PDW 233 produced only 18% of its maximum DMY after 40 days of growth. With application of 50?mg?Mn?kg?1 soil, the DMY significantly increased to 87% and 50% of the maximum for PBW 343 and PDW 233, respectively. These results indicate that aestivum cultivar PBW 343 was more Mn efficient than durum cultivar PDW 233. Manganese efficient cultivar PBW 343 had a lower internal Mn requirement than PDW 233 because at the same shoot Mn concentration PBW 343 produced more DMY. The root growth of both wheat cultivars was similar at sufficient Mn supply, the root length (RL)?:?DMY ratio being equal. At decreasing Mn supply root growth was depressed more strongly than shoot growth, the inhibition being more severe in Mn inefficient cultivar PDW 233, indicating the importance of root system size for Mn efficiency between these two wheat cultivars. A nutrient uptake model closely described Mn influx in both the cultivars, indicating that calculated concentration profiles were realistic and that chemical mobilization of Mn in the rhizosphere was not responsible for higher Mn efficiency of PBW 343. Calculated concentration profiles showed that in soil not fertilized with Mn, initial soil solution Mn concentration of 0.23?µM decreased to only 0.21?µM at the root surface after 27 days of uptake. This 7.4% decrease in Mn concentration at the root surface indicated that roots could not decrease Mn concentration to a lower value which would have caused higher transport of Mn to root surface and hence resulted in higher Mn influx.  相似文献   

4.
Wheat genotypes display differential tolerance to manganese (Mn) deficiency. Growing Mn-efficient cultivars in Mn deficient soil could be effective in improving yields. A pot experiment was conducted with eight genotypes grown in Mn deficient soil treated with 0 (no Mn fertilizer) and 50 ppm (50 mg Mn kg?1soil applied as mangansese sulfate monohydrate (MnSO4.H2O) Mn. The genotypes were classified on the basis of grain yield and grain physiological efficiency as efficient and responsive (SAMNYT 410, GLUPRO 200, PBW 621, and BW 9178), efficient and nonresponsive, inefficient and responsive (HD 2967), and inefficient and nonresponsive (PDW 314, PDW 291, and PBW 636). The genotypes in different groups differed in morphophysiological characteristics; efficient and responsive genotypes recorded more leaf area, higher SPAD index, higher Fv/Fm ratio, and longer roots than inefficient and nonresponsive. Efficient and responsive genotypes are desirable by farmers, whereas inefficient and responsive genotypes in a breeding program for their Mn-responsive characteristics.  相似文献   

5.
Abstract

Cultivars of triticale, wheat, and rye were grown with different N‐fertilizer rates and sampled at various maturity stages in 1975 to 1977. ‘6TA 131’ triticale, ‘Arthur’ wheat, and ‘Abruzzi’ rye were used as checks. Increasing N fertilizer rates increased dry matter and N accumulation in the above‐ground plant parts. However, after flowering losses of dry matter and N from the plants increased with N fertilizer rates. Triticale and rye generally absorbed more N from the soil than wheat. Triticale and wheat straw had higher P concentrations than rye. The head/straw concentration ratios were: triticale and rye>wheat for P, wheat>triticale and rye for K while Ca and Mg ratios were triticale>wheat>rye.  相似文献   

6.
Field experiments were conducted to study the response of cotton genotypes (G. arboreum Bt cv. RCH 650 BGII; non-Bt cv. F 2228; G. herbaceum cv. FDK 124) and wheat and triticale genotypes (T. aestivum cv. PBW 622; T. durum cv. PDW 314; triticale cv. TL 2908) to direct and residual B application (0, 0.5, 1.0, and 2.0 kg B ha?1 as borax) using a Typic Ustrochrept, neutral, noncalcareous, loamy sand and B-deficient soil. A significant response of 218 and 231 kg ha?1 in seed cotton yield was recorded with an application of 1.0 kg B ha?1 to cotton and 2.0 kg B ha?1 to wheat. A significant response of 152 kg ha?1 grain yield of wheat was observed with the application of 0.5 kg B ha?1 to wheat, while no residual effect of B was observed when B was applied to cotton. On the basis of agronomic and B uptake efficiency, genotypes of cotton (RCH 650 BG II > FDK 124 > F 2228) and wheat (PDW 314> TL 2908> PBW 621) responded differentially to B application, thus indicating that yield of Bt cotton and durum wheat will be reduced more than the other cultivars under B deficiency.  相似文献   

7.
Effects of varied irrigation and zinc (Zn) fertilization (0, 7, 14, 21 kg Zn ha‐1 as ZnSO47.H2O) on grain yield and concentration and content of Zn were studied in two bread wheat (Triticum aestivum), two durum wheat (Triticum durum), two barley (Hordeum vulgare), two triticale (xTriticosecale Wittmark), one rye (Secale cereale), and one oat (Avena sativa) cultivars grown in a Zn‐deficient soil (DTPA‐extractable Zn: 0.09 mg kg‐1) under rainfed and irrigated field conditions. Only minor or no yield reduction occurred in rye as a result of Zn deficiency. The highest reduction in plant growth and grain yield due to Zn deficiency was observed in durum wheats, followed by oat, barley, bread wheat and triticale. These decreases in yield due to Zn deficiency became more pronounced under rainfed conditions. Although highly significant differences in grain yield were found between treatments with and without Zn, no significant difference was obtained between the Zn doses applied (7–21 kg ha‐1), indicating that 7 kg Zn ha‐1 would be sufficient to overcome Zn deficiency. Increasing doses of Zn application resulted in significant increases in concentration and content of Zn in shoot and grain. The sensitivity of various cereals to Zn deficiency was different and closely related to Zn content in the shoot but not to Zn amount per unit dry weight. Irrigation was effective in increasing both shoot Zn content and Zn efficiency of cultivars. The results demonstrate the existence of a large genotypic variation in Zn efficiency among and within cereals and suggest that plants become more sensitive to Zn deficiency under rainfed than irrigated conditions.  相似文献   

8.
Spring wheat (Triticum aestivumL.) is the major crop species grown in south-western Australia and no responses of wheat to applied calcium (Ca) have been obtained in field experiments though responses have been obtained in glasshouse pot studies for wheat grown on the predominantly sandy acidic soils of the region. Since the mid 1990s canola (oilseed rape, Brassica napus L.) has been grown in rotation with wheat and has often developed symptoms of Ca deficiency when grown on sandy acidic soils in the field. The Ca requirement of canola in these soils is not known and was measured and compared with Ca requirements of wheat in the glasshouse study reported here when 5 amounts of Ca (0–630 mg Ca/pot), as calcium sulfate, were applied.

Application of Ca did not affect shoot production of wheat but increased grain yields by about 25% and 50 mg Ca/pot was required to produce 90% of the maximum grain yield. Two canola cultivars were grown, and both showed no shoot yield responses to applied Ca at early growth (GS1.5). However, at flower bud visible (GS3.5) shoots of triazine tolerant canola cv. ‘Karoo’ showed about 17% increase to applied Ca and required ～47 mg Ca/pot to produce 90% of the maximum yield, while corresponding values for cv. ‘Outback’ were 42% and 185 mg Ca/pot. Both canola cultivars showed large seed (grain) yield responses to applied Ca. Canola cv. ‘Outback’ produced no grain when no Ca was applied and showed ～ 97% increase to applied Ca and required about 462 mg Ca/pot to produce 90% of the maximum grain yield. The triazine tolerant cv. ‘Karoo’ produced about 22% of the maximum grain yield when no Ca was applied, showed approximately 78% grain yield response to applied Ca and required about 475 mg Ca/pot to produce 90% of the maximum grain yield. However, to produce 50% of the maximum grain yield, cv. ‘Outback’ required 250 mg Ca/pot while cv. ‘Karoo’ required about 100 mg Ca/pot. The grain yield response curve for cv. ‘Karoo’ was exponential and that for cv. ‘Outback’ was sigmoid so differences in the response curves were largest when small amounts of Ca were applied and decreased as more Ca was applied. Evidently canola cultivars differ in their ability to access soil and applied Ca providing opportunity to breed and select cultivars efficient at accessing soil and applied Ca. For both wheat and canola the concentration of Ca in dried shoots increased as more Ca was applied and, for each amount of Ca applied, the concentration of Ca in shoots decreased as plants matured. Both canola cultivars consistently had larger concentrations of Ca in shoots than wheat, either when no Ca was applied and for each amount of Ca applied, suggesting canola roots were better able to access soil and applied Ca than wheat roots. The Ca concentration in young wheat (GS15) and canola (GS1.5) shoots that was related to 90% of the maximum grain yield (critical Ca concentration) was 0.33% for wheat and 2.5% for both canola cultivars.  相似文献   

9.
In a greenhouse experiment, wheat cultivars PDW 291, PBW 550, and TL 2908 were grown in alkaline sandy-loam soil treated with sodium selenate at 0, 2, and 4 mg selenium (Se) kg?1 soil. Selenate-treated wheat plants accumulated greater Se in roots, stems, leaves, and grains and showed growth retardation, snow-white chlorosis, decreased shoot length and chlorophyll, and reduced leaf area and produced less number of grains as compared to control plants. Maximum reduction in these parameters was observed in selenate-treated TL 2908 plants and most of the plants died before maturity with almost no grain formation with 4 mg Se kg?1 soil. Selenium accumulation resulted in decreased reducing sugar, starch, and protein contents in grains whereas total free amino acids increased significantly in all the three cultivars. Selenium accumulation in wheat showed metabolic disturbances and its accumulation in grains was beyond toxic levels, thus making it unfit for consumption.  相似文献   

10.
Using six bread wheat genotypes (Triticum aesttvum L. cvs. Dagdas‐94, Gerek‐79, BDME‐10, SBVD 1–21, SBVD 2–22 and Partizanka Niska) and one durum wheat genotype (Triticum durum L. cv. Kunduru‐1149) experiments were carried out to study the relationship between the rate of phytosiderophore release and susceptibility of genotypes to zinc (Zn) deficiency during 15 days of growth in nutrient solution with (1 μM Zn) and without Zn supply. Among the genotypes, Dagdas‐94 and Gerek‐79 are Zn efficient, while the others are highly susceptible to Zn deficiency, when grown on severely Zn deficient calcareous soils in Turkey. Similar to the field observations, visual Zn deficiency symptoms, such as whitish‐brown lesions on leaf blades occurred first and severely in durum wheat Kunduru‐1149 and bread wheats Partizanka Niska, BDME‐10, SBVD 1–21 and SBVD 2–22. Visual Zn deficiency symptoms were less severe in the bread wheats Gerek‐79 and particularly Dagdas‐94. These genotypic differences in susceptibility to Zn deficiency were not related to the concentrations of Zn in shoots or roots. All bread wheat genotypes contained similar Zn concentration in the dry matter. In all genotypes supplied adequately with Zn, the rate of phytosiderophore release was very low and did not exceed 0.5 μmol/48 plants/ 3 h. However, under Zn deficiency the release of phytosiderophores increased in all bread wheat genotypes, but not in the durum wheat genotype. The corresponding rates of phytosiderophore release in Zn deficient durum wheat genotype were 1.2 umol and in Zn deficient bread wheat genotypes ranged between 8.6 μmol for Partizanka Niska to 17.4 umol for SBVD 2–22. In Dagdas‐94, the most Zn efficient genotype, the highest rate of phytosiderophore release was 14.8 umol. The results indicate that the release rate of phytosiderophores does not relate well with the susceptibility of bread wheat genotypes to Zn deficiency. Root uptake and root‐to‐shoot transport of Zn and particularly internal utilization of Zn may be more important mechanisms involved in expression of Zn efficiency in bread wheat genotypes than release of phytosiderophores.  相似文献   

11.
ABSTRACT

A greenhouse experiment with four bread wheat [Triticum aestivum L.] genotypes, ‘Rushan,’ ‘Kavir,’ ‘Cross,’ and ‘Falat,’ and a durum wheat [Triticum durum L.] genotype, ‘Dur-3,’ at two zinc (Zn) rates (0 and 15 mg Zn kg?1 dry soil) and four salinity levels (0, 60, 120, and 180 mM NaCl) was conducted. After 45 d of growth, the shoots were harvested, and Zn, iron (Fe), potassium (K), sodium (Na), and cadmium (Cd) concentrations were determined. In the absence of added Zn, visual Zn deficiency symptoms were observed to be more severe in ‘Dur-3’ and ‘Kavir’ than in other genotypes. The effect of Zn deficiency on shoot dry matter was similar to its effect on visual deficiency symptoms, such that shoot growth was most depressed in ‘Kavir’ and ‘Dur-3.’ At the 180 mM treatment, Zn fertilization had no effect on shoot dry matter of genotypes. Genotypes with high Zn efficiency had greater shoot Zn content than genotypes with low Zn efficiency. In the absence of added Zn, the Dur-3, and ‘Cross’ genotypes had the highest and lowest Cd concentrations, respectively. Application of Zn had a positive effect on salt tolerance of plants.  相似文献   

12.
Nineteen bush bean cultivars were screened for tolerance to excess Mn in nutrient solution and sand culture experiments. Seven‐day‐old seedlings were treated with full strength Hoagland No. 2 nutrient solution containing different Mn concentrations for 12 days in the greenhouse.

Cultivars showing the greatest sensitivity to Mn toxicity were ‘Wonder Crop 1’ and ‘Wonder Crop 2'; those showing the greatest tolerance were ‘Green Lord’, ‘Red Kidney’ and ‘Edogawa Black Seeded’.

Leaf Mn concentration of plants grown in sand culture was higher than that for plants grown in solution culture. The lowest leaf Mn concentration at which Mn toxicity symptoms developed, was higher in tolerant than in sensitive cultivars. The Fe/Mn ratio in the leaves at which Mn toxicity symptoms developed, was higher in the sensitive cultivars than in the tolerant ones.

We concluded that Mn tolerance in certain bush bean cultivars is due to a greater ability to tolerate a high level of Mn accumulation in the leaves.  相似文献   


13.
Carbon isotope discrimination (Δ) has been proposed as physiological criterion to select C3 crops for yield and water use efficiency. The relationships between carbon isotope discrimination (Δ), water use efficiency for grain and biomass production (WUEG and WUEB, respectively) and plant and leaf traits were examined in 20 Iranian wheat genotypes including einkorn wheat (Triticum monococcum L. subsp. monococcum) accessions, durum wheat (T. turgidum L. subsp. durum (Desf.) Husn.) landraces and bread wheat (T. aestivum L. subsp. aestivum) landraces and improved cultivars, grown in pots under well-watered conditions. Carbon isotope discrimination was higher in diploid than in hexaploid and tetraploid wheats and was negatively associated with grain yield across species as well as within bread wheat. It was also positively correlated to stomatal frequency. The highest WUEG and grain yield were noted in bread wheat and the lowest in einkorn wheat. Einkorn and bread wheat had higher WUEB and biomass than durum wheat. WUEG and WUEB were significantly negatively associated to Δ across species as well as within bread and durum wheat. The variation for WUEG was mainly driven by the variation for harvest index across species and by the variation for Δ within species. The quantity of water extracted by the crop, that was closely correlated to root mass, poorly influenced WUEG. Environmental conditions and genetic variation for water use efficiency related traits appear to highly determine the relationships between WUEG and its different components (water consumed, transpiration efficiency and carbon partitioning).  相似文献   

14.
Manganese (Mn) deficiency is a widespread problem on the alkaline soils, particularly for durum wheat (Triticum turgidum L. var. durum), which is more sensitive than either bread wheat or barley. The existence of considerable genetic variation in current germplasm of durum wheat (a relative yield of 58% in Stojocri 2 compared to 15% in check cv Yallaroi) and the development of a consistent selection criterion (Mn content of 35‐day‐old seedlings) has made breeding for Mn efficiency feasible. The development of Mn‐efficient durum wheat would be facilitated if the mode of inheritance was well understood. F1 hybrid, F2, and F2‐derived families from a cross between Stojocri 2 (moderately efficient) and Hazar (inefficient) were studied under controlled‐environment conditions. F1 hybrid was intermediate to the parents, indicating incomplete dominance and dependence on external Mn concentration. Analysis of 110 F2 and 220 F3 single plants (including 20 F2‐derived F3 families) showed that the observed variance was in agreement with the expected variance of a population segregating for two genes. Chi‐square analysis of the segregation ratios of F3 families also supported the digenic segregation hypothesis. Currently Stojocri 2 is used in a breeding program for the transfer of Mn efficiency to commercial varieties, by backcrossing (two backcrosses retain about 88% of recurrent parent genotype).  相似文献   

15.
Durum wheat (Triticum turgidum L. var durum) is a species that accumulates cadmium (Cd). Durum wheat cultivars differ in their absorption ability of Cd; therefore, identifying and selecting genetic material with low Cd accumulation reduces human exposure to this toxic element. In the present study, Cd concentration was evaluated in three Chilean durum wheat cultivars (Llareta-INIA, Corcolén-INIA, and Lleuque-INIA) grown in four Chilean locations with varying concentrations of Cd in soils. The objective of this study was to evaluate the response of these durum wheat cultivars to different doses of cadmium in terms of grain yield; Cd concentration in different plant tissues (grain, straw, roots); soil Cd concentration was also evaluated. Results show that grain yield was not affected by soil Cd; differences in Cd concentration in plant tissues were generally associated with location, cultivar, and soil Cd concentration. Grain Cd concentration in all three cultivars was classified in the low accumulation category for this metal; ‘Lleuque-INIA’ noted as having a very low accumulation.  相似文献   

16.
Two‐dimensional isoelectric focusing (IEF) × PAGE gels were used to compare the endoproteolytic (gelatinase) activities of germinated barley with those of bread and durum wheat, rye, triticale, oat, rice, buckwheat, and sorghum. Barley was used as the standard of comparison because its endoproteinase complement has been studied previously in the greatest detail. The characteristics of the grain proteases were appraised from their migration patterns and by how they were affected by pH levels. All of the germinated grains contained multiple enzyme activities and their separation patterns and pH levels were at least similar to those of barley. The proteinases of the bread and durum wheats, rye, oat, and sorghum were most similar to those of barley, whereas the other grains provided more varied patterns. The rice and buckwheat proteinases developed much more slowly than those of the other grains. The activity patterns of the triticale resembled those of the parents, wheat and rye, but the triticale contained many more activities and higher overall proteolytic activities than any of the other species. These results should be applied to scientific or commercial procedures with caution because grains contain potent endogenous proteinase inhibitors that could inactivate some of these enzymes in various tissues or germination stages.  相似文献   

17.
夏越  沈仁芳  马建锋  车景 《土壤》2023,55(6):1207-1215
锰是植物生长发育所必需的微量营养元素，缺锰会导致植株矮小，叶片黄化，发育不良等，严重时可致植株死亡。水稻和小麦是我国主要的粮食作物，但种植在有效锰含量不同的土壤中；水稻主要种植在锰有效性高的南方酸性土壤中，小麦主要种植在有效锰含量低的北方石灰性土壤中。为探究水稻和小麦响应缺锰的差异及其机理，本研究采用水培法比较了水稻和小麦苗期在缺锰和加锰处理条件下的生长情况以及植株各部位元素含量和分配情况，并采用绝对定量法比较了小麦和水稻中锰转运基因的表达水平。研究结果表明，与供锰充足的植株相比，缺锰三周严重抑制水稻的生长，而不影响小麦的生长；在缺锰条件下，小麦根到地上部的转运率比供锰充足时提高了16.4%；相反，水稻体内锰从根到地上部的转运率降低了7.5%；苗期小麦根中TaNRAMP2的绝对表达量是水稻OsNRAMP2的3.8-5.1倍。这些结果表明，小麦比水稻更耐缺锰胁迫，这可能与NRAMP2在小麦中的高表达有关。  相似文献   

18.
Root uptake of lipophilic zinc-rhamnolipid complexes   总被引：1，自引：0，他引：1  
This study investigated the formation and plant uptake of lipophilic metal-rhamnolipid complexes. Monorhamnosyl and dirhamnosyl rhamnolipids formed lipophilic complexes with copper (Cu), manganese (Mn), and zinc (Zn). Rhamnolipids significantly increased Zn absorption by Brassica napus var. Pinnacle roots in (65)Zn-spiked ice-cold solutions, compared with ZnSO4 alone. Therefore, rhamnolipid appeared to facilitate Zn absorption via a nonmetabolically mediated pathway. Synchrotron XRF and XAS showed that Zn was present in roots as Zn-phytate-like compounds when roots were treated with Zn-free solutions, ZnSO4, or Zn-EDTA. With rhamnolipid application, Zn was predominantly found in roots as the Zn-rhamnolipid complex. When applied to a calcareous soil, rhamnolipids increased dry matter production and Zn concentrations in durum (Triticum durum L. cv. Balcali-2000) and bread wheat (Triticum aestivum L. cv. BDME-10) shoots. Rhamnolipids either increased total plant uptake of Zn from the soil or increased Zn translocation by reducing the prevalence of insoluble Zn-phytate-like compounds in roots.  相似文献   

19.
Plant genotypes differ in their capacity to grow in soils with low manganese (Mn) availability. The physiological mechanisms underlying differential tolerance to Mn deficiency are poorly understood. To study the relationship between Mn content in soil, plant genotypes, and rhizosphere microorganisms in differential Mn efficiency, two wheat (Triticum aestivum L.) cultivars, RAC891 (tolerant to Mn deficiency) and Yanac (sensitive), were grown in a Mn‐deficient soil to which 5, 10, 20 or 40 mg Mn kg–1 were added. The shoot dry matter of both cultivars increased with increasing Mn addition to the soil. At all soil Mn fertilizer levels, the tolerant RAC891 had a greater shoot dry matter and a higher total shoot Mn uptake than the sensitive Yanac. The concentration of DTPA‐extractable Mn in the rhizosphere soil of RAC891 at Mn20 and Mn40 was slightly lower than in the rhizosphere of Yanac. The population density of culturable microorganisms in the rhizosphere soil was low (log 6.8–6.9 cfu (g soil)–1) in both cultivars and neither Mn oxidation nor reduction were observed in vitro. To assess the non‐culturable fraction of the soil microbial community, the ribosomal intergenetic spacer region of the bacterial DNA in the rhizosphere soil was amplified (RISA) and separated in agarose gels. The RISA banding patterns of the bacterial rhizosphere communities changed markedly with increasing soil Mn level, but there were no differences between the wheat cultivars. The bacterial community structure in the rhizosphere was significantly correlated with the concentration of DPTA‐extractable Mn in the rhizosphere, fertilizer Mn level, shoot dry matter, and total shoot Mn uptake. The results obtained by RISA indicate that differential tolerance to Mn deficiency in wheat may not be related to changes in the composition of the bacterial community in the rhizosphere.  相似文献   

20.
Analysis and research on the nutrition of some Australian native plants as well as diagnostic analysis of failed native plant gardens reinforces the view that manganese (Mn) availability is a major factor in the edaphology and cultivation of Australian native species. Yellow Kandosol soils on sandstone show a unique endemic floral assemblage. These soils show low total soil Mn levels of only 20–30 mg/kg. Despite this, endemic species such as Eucalyptus haemastoma and Acacia suaveolens show greater foliar Mn levels (around 291 and 389 mg/kg, respectively) than iron (Fe) levels, with Fe/Mn ratios as low as 0.14 and 0.27. During pot trial work on artificial soils created from crushed sandstone and green waste compost that were designed to research phosphorus (P) and calcium (Ca) nutrition, some interesting data on Mn uptake were collected. Levels of foliar Mn as high as 1250 and 389 mg/kg, respectively, accumulated in E. haemastoma and A. suaveolens when soils were artificially acidified to pH 4.7 (CaCl2) using ferrous sulfate. These Mn levels were associated with visible toxicity symptoms in foliage of E. haemastoma but not in A. suaveolens. Foliar Mn in both species showed a strong inverse correlation (R2 > 0.93) with soil pH. Previous research has shown that eucalypts from this floral assemblage are prone to Mn toxicity when grown in conditions of high soil Mn availability. Diagnostic analysis of soils and foliage for a client with horticultural problems in a native plant landscape showed severe chlorosis in a wide range of native species due to Mn deficiency induced by neutral soil pH (around 7.0 in CaCl2). Such soil pHs are considerably greater than those of the plant’s natural distribution. Despite apparently elevated soil P and the appearance of what looked like P toxicity, foliar P levels were not sufficiently elevated to conclude acute P toxicity but rather simple and severe Mn deficiency. The work suggests that induced Mn deficiency and toxicity may be underdiagnosed problems in the cultivation of many Australian native plants.  相似文献   

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