摘要:

Six sorghum [Sorghum bicolor(L.) Moench] genotypes with varying tolerance to Al were grown in greenhouse experiments with acid Cecil sandy clay loam (clayey, Kaolinitic, thermic, Typic Hapludults) at pH 4.4 with and without vesicular‐arbuscular mycorrhizal (VAM) fungus [Glomus deserticola(Trappe, Bloss, and Menge)]. The effects of VAM colonization on mineral element uptake and sorghum genotype tolerance to Al were investigated. Sorghum genotypes maintained their tolerance or susceptibility to acid soil conditions even when plants were colonized with VAM. Mycorrhizal and nonmycorrhizal plants had similar shoot N, P, S, K, Ca, Mg, Al, Mn, Fe, Zn, and Cu contents, except for one genotype (SC283). SC283 had lower mineral element contents in mycorrhizal compared to nonmycorrhizal plants. Soil Al availability may have reduced VAM colonization of sorghum roots and VAM activity in the soil.

ISSN:0010-3624    

DOI:10.1080/00103628809367984

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effects of the vesicular‐arbuscular mycorrhizal (VAM) fungusGlomus deserticola(Trappe, Bloss, and Menge) on growth and mineral element uptake of sorghum [Sorghum bicolor(L.) Moench] were investigated in greenhouse experiments with acid Cecil sandy clay loam (clayey, kaolinitic, thermic, Typic Hapludults) at five pH values (4.1 to 5.8). Control experiments consisted of sterile VAM inocula. Dry matter yields and mineral element uptake were markedly depressed at pH 4.1, were relatively high at pH 4.5, and remained fairly constant from pH 4.5 to 5.8 in mycorrhizal plants. Dry matter yields, root lengths, and mineral element contents of nonmycorrhizal plants increased as soil pH increased, and these characteristics were similar to mycorrhizal plants only after the soil was above pH 5.0 to 5.5. Mycorrhizal plants had higher total and efficiency uptake of mineral elements (shoot element content/root dry matter ratio) than nonmycorrhizal plants. Available Al in acid soils may have been detrimental to VAM infection with sorghum roots and for VAM fungal activity at low soil pH.

ISSN:0010-3624    

DOI:10.1080/00103628809367985

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effects of acidity and high levels of Al upon the growth of four strains ofBradyrhizobium japonicumwere compared in three strongly acidic soil extracts and in liquid defined medium. In all media the times for the strains to increase in cell density by a factor of 50,000 (i.e., become slightly turbid) increased as pH was decreased in treatments that included pH values of 6.7, 5.1, 4.8, and 4.6. Addition of 15 or 25 μM Al at pH 4.8 produced no detrimental effects in all media, whereas addition of 50 μM Al adversely affected the growth ofB. japonicumat pH 4.6. At a given concentration of total AlB. japonicumin general grew as well in defined medium as in soil extract media which would be expected to contain organic Al‐detoxifying agents. Growth curves indicated that the growth reduction by acidity and Al toxicity in the turbidity studies was the result of sustained decreased growth rates and not simply the result of an initial lag period.

ISSN:0010-3624    

DOI:10.1080/00103628809367986

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Field experiments were conducted with alfalfa (Medicago sativaL. var Peace) planted on a soil with pH 5.8. Granular inoculant was applied with the seed, below the seed or beside the row, or liquid inoculant was applied beside the row. The inoculants were prepared withRhizobium melilotiNRG‐61 which had been selected for low‐pH tolerance. Forage yield, nodule numbers and weight, and inoculant strain occupancy of nodules were measured. Granular inoculant applied with or below the seed resulted in greater than 87% of the nodules occupied by strain NRG‐61 and increased nodule numbers and weight and forage yield when the moisture conditions for germination and plant establishment were favorable. Under moisture limiting conditions, the inoculant had little effect. The use of granular or liquid inoculant banded beside the row after crop establishment was not effective in improving nodulation nor increasing forage yield.

ISSN:0010-3624    

DOI:10.1080/00103628809367987

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Aluminum (Al) toxicity is an important growth‐limiting factor for plants in many acid soils. The problem is not always economically correctable with conventional liming practices. But plant species and genotypes within species differ widely in tolerance to excess Al, and some of these differences are genetically controlled. Hence, an alternative or supplemental approach to the problem is to select or breed plant genotypes having greater tolerance to Al. A plant genetic approach has great potential for solving difficult soil fertility problems such as Al toxicity in acid subsoils. An important part of this approach is the determination of plant genetic, physiological and biochemical mechanisms by which plants tolerate mineral stress. Better understanding of stress tolerance mechanisms could lead to the development of more tolerant plants and more effective liming and fertilization practices for plants already in use. The objective of this presentation is to discuss our state of knowledge concerning the range of plant tolerance to excess Al, genetic control of tolerance and release of Al‐tolerant germplasm, and plant physiological and biochemical characteristics associated with differential Al tolerances among genotypes within species.

ISSN:0010-3624    

DOI:10.1080/00103628809367988

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The root system of alfalfa (Medicago sativaL.), known for extreme sensitivity to Al toxicity, has been observed to penetrate acid subsoil horizons high in exchangeable Al. In our previous studies we noted that root penetration into acid subsurface horizons occurred where lime had been surface applied under both no‐till and conventional tillage management systems. In order to more fully understand this seeming contradiction, the present study was undertaken. It was hypothesized that exchangeable Al may not be an adequate indicator of the activity of Al in solution and consequently the potential toxicity to the plant may be over estimated.

ISSN:0010-3624    

DOI:10.1080/00103628809367989

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Studies were conducted to determine mineral element concentrations in leaves of sorghum [Sorghum bicolor(L.) Moench] genotypes that were tolerant and susceptible to acid soil conditions, and to assess imbalances and changes in mineral elements in these genotypes grown at 60 (relatively severe Al stress, pH 4.1) and 40% (less severe Al stress, pH 4.6) Al saturation on an acid ultisol in Colombia, South America. Leaf concentrations of S, K, Al, Mn, and Fe were lower and concentrations of Ca and Si were higher in tolerant genotypes when plants were grown at 40 compared to 60% Al saturation. Susceptible genotypes had higher dry matter yield and leaf concentrations of Ca and Si, and lower concentrations of Mg, Al, Mn, Fe, and Zn when plants were grown at 40 compared to 60% Al saturation. At 60% Al saturation tolerant genotypes had higher dry matter yields and concentrations of Ca and Si and lower concentrations of P, S, Al, and Fe than susceptible genotypes. At 40% Al saturation, tolerant genotypes had higher dry matter yield and lower concentration of N, P, and S than susceptible genotypes. The largest changes in growth and mineral element concentrations were for susceptible genotypes grown at 60 compared to 40% Al saturation. The elements to show the greatest amount of change were increases in Ca and Si and decreases in Al, Mn, and Fe when plants were grown at 40 compared to 60% Al saturation.

ISSN:0010-3624    

DOI:10.1080/00103628809367990

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Sorghum [Sorghum bicoior(L.) Moench] genotypes show large differences in dry matter and yield when grown on many tropical acid soils. The objective of this study was to determine differences in mineral element concentrations in sorghum genotypes grown on an acid oxisol limed with 2 and 6 Mg dolomitic limestone ha‐1in Colombia, South America. Fifty genotypes showed differences in dry matter yield and concentrations of P, K, Ca, Mg, S, Si, Al, Mn, Cu, and Zn. Liming did not change low, high, and mean leaf concentrations of P, K, Mg, S, and Cu for the genotypes. Concentrations of Al, Mn, and Fe in the genotypes were higher in leaves of plants grown at 2 (pH 4.5 and 62% AT saturation) than at 6 Mg lime ha‐1(pH 4.8 and 34% Al saturation). At the 6 Mg ha‐1lime rate, leaf concentrations of Ca and Si increased. Silicon may have reduced the effects of toxic Al, and possibly toxic Fe. Genotypes showed sufficient variability in mineral element concentrations that selection for improved values of these traits appears feasible.

ISSN:0010-3624    

DOI:10.1080/00103628809367991

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Concrete lysimeters were filled with a Hebert sandy loam (pH 5.2, 1.5% Organic Carbon) and 5 rooted cuttings of either Augusta (ME3) or Chignecto (508) lowbush blueberries (Vaccininm angnst‐ifoliumAit.) were planted into each lysimeter in July, 1982. Fertility treatments were applied annually (1983–1985) in 3 replicates for each of the 2 clones. Amendments were Control, Fertilizer (500 kg/ha of 10–10–10), Dairy Manure and Green Manure; the manures were applied at the equivalent of 50 kg N/ha. Leach‐ates were collected from spring to late fall 1983–1985. Leachates and stem, leaf and root tissue samples were collected and analysed for macro‐ and micronutrients. Soil samples from two depths were collected and extracted for available macronutrients, pH and OC. There were significant differences throughout the plant in the tissue nutrient content between cultivars due to treatments. A consistent observation was the reduced level of Mg and increased level of Mn in plants treated with Fertilizer, which related to the lower soil pH induced by the Fertilizer. Soil fertility characteristics varied between treatments and the soil sampling depth. Soil fertility was a reflection of the nutrient content of the amendments applied over the three year period.

ISSN:0010-3624    

DOI:10.1080/00103628809367992

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Internal bark necrosis (IBN), a disorder that stunts tree growth, was examined in 18 ‘Delicious’ apple (Malus domesticaBorkh.) orchards with histories of IBN in the Okanagan Valley of British Columbia. Leaves were sampled from 3 to 6 trees in each orchard and a composited soil sample was collected from the 5–20 cm depth beneath the same trees. The orchards were classed for IBN bark symptoms as none, moderate and severe. Leaf and soil B levels were in the adequacy range; IBN was therefore attributed to Mn toxicity. IBN was not related to rootstocks which varied within each IBN class. Tree ages averaged 12 and 4 years, respectively, for the none and severe IBN classes. Leaf Mn increased from 67 to 233 to 306 mg kg‐1in association with none to moderate to severe IBN symptoms. Severity of IBN was not associated with leaf Ca. IBN showed little or no relationship with soil pH, 0.02 M CaCl2‐Mn or exchangeable bases, even though they differed widely between orchards. Correlation coefficients between leaf Mn or leaf Ca and soil properties were not higher than 0.57 (P <0.05). The effectiveness of lime applications in several of these orchards, usually on the soil surface, for correcting IBN is discussed.

ISSN:0010-3624    

DOI:10.1080/00103628809367993

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor