Aluminum tolerances of two snapbean cultivars related to organic acid content evaluated by high‐performance liquid chromatography

High‐performance liquid chromatography (HPLC) was used to determine aluminum (Al)‐induced changes in organic acid (OA) concentrations of Al‐tolerant ‘Dade’ and Al‐sensitive ‘Romano’ snapbean cultivars. Two week old ‘Dade’ and ‘Romano’ snapbean were grown in 1/5‐strength Steinberg nutrient solution for 10 days and then subjected to 0, 2, 4, 6, and 8 mg L^‐1 Al treatments at pH 4.5 for an additional 3–15 days. Current studies confirmed earlier findings that the Dade cultivar was significantly more tolerant to Al than the Romano variety. Organic acid analyses were performed on extracts of root and leaf, and on stem exudates. The organic acids were separated on an ion exclusion column using a mobile phase of 0.01 N H₃PO₄. Individual OA were quantified with a variable wavelength detector operating at 210 nm. Aluminum stress tended to reduce the concentrations of citric, malonlc, malic, glycolic, fumaric, and acetic acids in the roots and increased the OA concentrations in stem exudates. In the presence or absence of Al stress, the Al tolerant Dade cultivar contained higher OA concentrations than did the Al‐sensitlve Romano. Aluminum stress reduced total OA levels in root extracts from Al‐sensltive Romano plants to a greater extent than in those of the Al‐tolerant Dade. Malic and citric acid concentrations were decreased more than those of the other organic acids examined. Results indicate that the Al‐tolerant Dade snapbean cultivar has a higher potential for Al‐chelation and detoxification than does the Al‐sensitive Romano. Hence, an Al‐chelation mechansism may be involved in differential Al tolerance within this species.     

Tolerance of barley cultivars to an acid,aluminum‐toxic subsoil related to mineral element concentrations in their shoots

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.     

Response of wheat cultivars to different soil nitrogen and moisture regimes: II. Nitrogen up‐take,partitioning and influx 1

Nitrogen (N) is one of the major mineral nutrients required for growth and development of plants. Soil water availability, N concentration at the root surface and the ability of plants to absorb N are the most important factors that affect N uptake and partitioning. The objective of this study was to use greenhouse and growth chamber environments to investigate how two contrasting water regimes (stress and nonstress) and different soil N concentrations affect the uptake and distribution of N among different plant parts of three cultivars of wheat (Triticum aestivum L.) at different stages of development Results showed that at the beginning of stem elongation and under non N limiting conditions, there was a high and positive correlation between shoot dry matter production and shoot N content. Under N deficient soils that received different N rates, shoot N content was more related to shoot N concentration than to dry matter. Root growth and N content of the ‘Saada’ cultivar were negatively affected by high soil N concentration. Under mild water stress or nonstressed conditions, N uptake by the shoot increased with increased soil N in all cultivars. Overall, severe water stress masked the effect of N supply, and decreased N uptake in the case of ‘Merchouch 8’ and ‘Saada’. Root N content was not affected by water stress but increased when N was supplied. At anthesis and after rewatering plants from boot stage to anthesis, the plants fully recovered, and those that were water stressed, increased their N absorption to a rate much higher than those that were stressed. Nitrogen influx (NI) decreased with water stress, but increased more with increased soil N under well watered conditions than under stress. “Merchouch 8’ had higher NI than ‘Saada’. From this study we can conclude that the effect of N supply on N content was masked by severe water stress, and ‘Nesma’ was less sensitive to this stress. At anthesis, plants that were previously water stressed increased their rate of N uptake during the recovery. Root N was not affected by water stress but increased when soil N was increased.     

Acid phosphatase activity and vesicular‐arbuscular mycorrhizal infection associated with roots of four wheat cultivars

Acid phosphatase activity and vesicular‐arbuscular mycorrhizal (VAM) infection associated with four spring wheat genotype roots were investigated. Plants were grown in a typic low P volcanic soil with and without P‐fertilizer addition and harvested at 21, 42, 63, 84 and 96 days. Results show that phosphatase activity, expresed as ug p‐nitrophenol released per g dry root, decreased from 21 to 96 days in all cultivars. Conversely, trends of VAM infection were similar in all genotypes being higher in P added plants at 63 days after sown. This opposite effects may be viewed as alternative and/or complementary adaptations for P‐uptake by plants growing in low nutrient situations. It was concluded that one of the ways of P‐alleviation in wheat growing in our volcanic soils might be the search of genotypes having high biochemical and/or biological root activities.     

Spatial variation of soil test phosphorus and potassium,oxalate‐extractable iron and aluminum,phosphorus‐retention index,and organic carbon content in soils of Western Australia

Abstract

Spatial variation of bicarbonate soil test phosphorus (P) and bicarbonate soil test potassium (K) was studied by measuring soil test values for 40 individual soil samples collected from random locations within eight uniform 100 m by 100 m field sites in south‐western Australia. In addition, for five of the sites, spatial variation of the three P sorption indices (ammonium oxalate extractable iron, ammonium oxalate extractable aluminum, and the P retention index) and of organic carbon (C) was measured for 20 individual soils samples. Spatial variation was found to be large, with coefficient of variation (CV) exceeding 20% in most cases, and 50% in some cases. It is therefore essential to collect an adequate number of soil samples from uniform areas in paddocks in order to provide a representative composite sample to measure the soil properties.     

Tolerance of durum wheat lines to an acid,aluminum‐toxic subsoil

Durum wheat, Triticum durum Desf., is reportedly more sensitive to aluminum (Al) toxicity in acid soils than hexaploid wheat, Triticum aestivum L. em. Thell. Aluminum‐tolerant genotypes would permit more widespread use of this species where it is desired, but not grown, because of acid soil constraints. Durum wheat germplasm has not been adequately screened for acid soil (Al) tolerance. Fifteen lines of durum wheat were grown for 28 days in greenhouse pots of acid, Al‐toxic Tatum subsoil at pH 4.5, and non‐toxic soil at pH 6.0. Aluminum‐tolerant Atlas 66 and sensitive Scout 66 hexaploid wheats were also included as standards. Based on relative shoot and root dry weight (wt. at pH 4.5/wt. at pH 6.0 X 100), durum entries differed significantly in tolerance to the acid soil. Relative shoot dry weight alone was an acceptable indicator of acid soil tolerance. Relative dry weights ranged from 55.1 to 15.5% for shoots and from 107 to 15.8% for roots. Durum lines PI 195726 (Ethiopia) and PI 193922 (Brazil) were significantly more tolerant than all other entries, even the Al‐tolerant, hexaploid Atlas 66 standard. Hence, these two lines have potential for direct use on acid soils or as breeding materials for use in developing greater Al tolerance in durum wheat. Unexpectedly, the range of acid soil tolerance available in durum wheat appears comparable to that in the hexaploid species. Hence, additional screening of durum wheat germplasm for acid soil (Al) tolerance appears warranted. Durum lines showing least tolerance to the acid soil included PI 322716 (Mexico), PI 264991 (Greece), PI 478306 (Washington State, USA), and PI 345040 (Yugoslavia). The Al‐sensitive Scout 66 standard was as sensitive as the most sensitive durum lines. Concentrations of Al and phosphorus were significantly higher in shoots of acid soil sensitive than in those of tolerant lines, and these values exceeded those reported to cause Al and phosphorus (P) toxicities in wheat and barley.     

Distribution of DTPA‐extractable Fe,Zn, and cu in soil particle‐size fractions

Abstract

To examine the distribution of DTPA‐extractable Fe, Zn, and Cu in clay, silt, and sand fractions; surface soils were collected from cultivated fields of North Dakota, South Dakota, West Virginia, Iowa, Ohio, and Illinois. Clay, silt, and sand fractions were separated after sonic dispersion of soil water suspension and analyzed for DTPA‐extractable Fe, Zn, and Cu. In general, clay had the highest and sand the lowest amount of DTPA‐extractable metals. Consequently, clay had the highest and sand the lowest intensity and capacity factors for these metals since DTPA micronutrient test measures both these factors.     

Ozone tolerances of soybean cultivars and near‐isogenic lines in a fumigation chamber

Ozone (O₃) toxicity is a potential yield‐limiting factor for soybean (Glycine max L. Merr.) in the United States and worldwide. The most economical solution to the problem is to use O₃‐tolerant cultivars. Thirty‐four cultivars and 87 near‐isogenic lines (NILS) of soybean were screened for O₃ tolerance in a fumigation chamber (250 ppb for three hrs). Most tolerant cultivars tested were ‘Cloud’, ‘T‐276’, ‘T263’, and ‘Kindu’. Moderately tolerant cultivars included ‘Davis’, ‘T‐210’, and ‘Elton’. Most sensitive cultivars were ‘Corsoy 79’, ‘Noir’, and ‘Midwest’. The original ‘Clark’ cultivar was not tested, but ‘Clark 63’ tended to be more tolerant than ‘Harosoy’. The aluminum (Al)‐tolerant ‘Perry’ cultivar also tended toward greater O₃ tolerance than the Al‐sensitive ‘Chief’, as observed earlier. Our rankings of ‘Hark’ as moderately sensitive and ‘Davis’ as moderately tolerant are also in agreement with earlier reports. Among NILS, the order of O₃ tolerance was generally Williams>Clark>Harosoy, but differences were also observed within these parental groups. For example, L68–560 was more tolerant than some other NILS of ‘Harosoy’. ‘L76–1988’ appeared more tolerant to O₃ than other NILS of ‘Williams’, but all ‘Williams’ NILS were more tolerant than most NILS of ‘Harosoy’ and ‘Clark’. Ozone‐tolerant and ‐sensitive soybean cultivars or NILS identified in our study may be useful tools in studies on mechanisms of 03 tolerance and differential 03 tolerances in plants and in the development of ameliorative measures.     

Sensitivity of soft red winter wheat cultivars to chlorate‐induced toxicity

The use of chlorate as a nitrate analogue to screen soft red winter wheat (Triticum aestivum L.) cultivars for differences in nitrate reductase activity (NRA) was studied by adding potassium chlorate to a hydroponic nutrient solution in which wheat seedlings were growing. After 14 days, leaf symptoms indicating chlorate‐induced toxicity were rated. It was hypothesized that wheat plants which were susceptible to chlorate‐induced toxicity reduced chlorate and nitrate more rapidly than did resistant plants. In experiments testing the potential of this assay, wheat and barley (Hordeum vulgare L.) cultivars previously reported to have low NRA were less susceptible to chlorate‐induced toxicity than were cultivars reported to have high NRA. The assay was used to screen 15 soft red winter wheat cultivars for differences in sensitivity to chlorate‐induced toxicity. Variable toxic reactions were observed both among and within the cultivars. To determine whether the within‐cultivar variation was environmental or genetic, single plant selections for contrasting chlorate response were made, and bulked progeny were rescreened. In eight of 15 cultivars, the contrasting selections were different for chlorate‐induced toxic response, indicating heterogeneity for this trait within these eight cultivars. These chlorate‐selected lines may also be near‐isogenic lines for NRA. Seedling screening of wheat for chlorate response may be useful for identification of high NRA breeding lines.     

Influence of soil particle size and grinding on bray‐2 extractable phosphorus

Abstract

The influence of soil particle size and soil fine grinding on Bray‐2 extractable phosphorus (Bray‐2P) was studied. Air‐dried and 2‐mm mesh‐sieved soil was separated into six particle size classes: <0.075, 0.075–0.106, 0.106–0.25, 0.25–0.425, 0.425–0.85, and 0.85–2 mm. The lowest amounts of Bray‐2P were found in the 0.425–0.85 and 0.85–2 mm fractions and the highest in <0.075 mm fraction. When ground for 3 min, the amount of Bray‐2P increased in the fractions larger than 0.25 mm, whereas it decreased in the fractions smaller than 0.25 mm. In the large fraction (0.425–0.85 mm), grinding for 1 to 3 min led to an increase in the amount of Bray‐2P, but grinding for 9 to 18 min caused a decrease. In contrast, in the small fraction (<0.075 mm), the amount of Bray‐2P decreased by grinding for 1 min. The large and small fractions that were ground absorbed P in proportion to the grinding time during the extraction‐filtration period.     

Mehlich‐1‐ and DTPA‐extractable lead in soils in relation to soil properties

Abstract

Mehlich‐1 and DTPA extractants are frequently used to predict metal availability in soils. Metal extractability by the acid or chelate extractant reflects the metal characteristics and metal‐soil interactions. In this study, samples of eight topsoils from the southeastern United States were incubated with added lead (Pb) at the rate of 40 mg#lbkg^‐1. After five months in the greenhouse, Mehlich‐1 and DTPA extractants were employed to extract Pb in both metal‐amended and natural soils. For the natural soils, Pb concentration in the DTPA extractant was always higher than that in the Mehlich‐1 extractant. This indicates that the DTPA chelate extractant is able to dissolve some Pb in soils which is not solubilized by protons. The negative correlation found between Mehlich‐1‐extractable Pb and soil clay content might result from two mechanisms: i) strong association between Pb and soil surfaces, or ii) readsorption of Pb during extraction. None of the correlations between DTPA‐extractable Pb and soil properties was significant, suggesting that the DTPA‐extractable Pb is not heavily dependent on soil properties. The DTPA extractant showed a high ability to solubilize Pb in the natural soils possibly due to a high affinity of Pb for soil organic matter.     

Effect of PCMBS on calcium‐ or aluminum‐induced curvature in roots of two watermelon cultivars

Unilateral application of calcium (Ca) or aluminum (Al) in agar to the primary roots of watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] cultivars ‘Dixielee’ and ‘Mirage’ induced root curvature. Root curvature induced by Al was greater than that induced by Ca in both cultivars. PCMBS inhibited Al‐induced root curvature in both cultivars, but had no effect on Ca‐induced curvature. The inhibition of curvature indicated that PCMBS reduced Al uptake. ‘Dixielee’ was more responsive to PCMBS than was ‘Mirage’.     

Agronomic effectiveness of phosphate rock and superphosphate for aluminum‐tolerant and non‐tolerant sorghum cultivars

Abstract

About 35% of soils in Venezuela are acid and low in available phosphorus (P). To solve this problem farmers lime and apply phosphate fertilizers to the soils, but both lime and fertilizers are expensive. A good alternative to overcome soil acidity is the use of aluminum (Al)‐tolerant cultivars. The objective of this study was to test the hypothesis, by use of a pot experiment, that sorghum cultivars tolerant to Al toxicity are able to use P from phosphate rock more efficiently than are susceptible cultivars. Three sorghum (Sorghum bicolor L. Moench) cultivars, Chaguaramas III (Ch), AI‐tolerant, Decalb D59 (D59), and Pioneer 8225 (Pi), both Al‐susceptible, were grown in the greenhouse for 20 and 35 days in two acid soils fertilized with 0 and 100 mg P kg^‐1 as triple superphosphate (SP) and Riecito phosphate rock (PR). Santa Maria soil was very low in available P (2 mg kg^‐1) and highly saturated in Al saturation (64.5%) and Pao soil was higher in available P (20 mg kg^‐1) and low in Al saturation (6.5%). Chaguaramas dry matter production, P uptake and root length was higher in Santa Maria soil as compared with Pi and D59 when grown with both SP and PR fertilization. Chaguaramas response to PR in Pao soil was not as good as in Santa Maria soil. The results of our experiment suggest that Al‐tolerant Ch is able to utilize P from PR more efficiently in soils like Santa Maria than Al‐susceptible cultivare Pi and D59.     

Effect of extractable zinc,phosphorus, and soil ph on zinc concentrations in leaves of field‐grown corn

Abstract

The variability in corn yield responses to applications of Zn fertilizer appears to be associated with several complex soil and climatic factors that affect the availability of endogenous soil Zn to the crop under specific conditions. Among the soil chemical properties that influence availability of endogenous Zn are soil pH, organic matter content, and extractable P. Over a period of several years, soil and plant analysis data were collected from 54 field experiments, field trials, and diagnostic visits to producer's fields. These data were subjected to multiple regression analysis, resulting in an equation: Zn_leaf = 37.14 + 1.513 Zn_st ‐4.04 pH_st ‐ 1.791 ln(P_st/100) where Zn_st, pH_st, and P_st were 0.1N HC1 extractable soil Zn (kg/ha), 1:1 soil‐water pH, and Bray's 1 extractable soil P (kg/ha), respectively. These factors accounted for 67% of variation in leaf Zn, which was a large portion of the variability in Zn_leaf considering that climatic conditions, management levels, and varietal differences were uncontrolled in most instances. Using the previously published critical level in the leaf opposite and below the ear as 17 μg Zn/g, these data can be used to set required soil test levels of Zn at different levels of extractable P and soil pH. Inadequate levels of extractable Zn would range from 2.5 (at pH 6.0, P = 70 kg/ha) to, 9.5 kg/ha (at pH 7.5, P = 420 kg/ha).     

Evaluation of soil extractants to estimate available micronutrients under wheat‐field conditions

Abstract

Three extracting reagents were evaluated by correlation analyses to provide the best index of Zn, Cu, Mn and Fe availability to wheat (Triticum aestivum L.) plants growing under open field conditions. Twenty one soils were selected to obtain the widest range in properties of soils of the land wheat cultivated. The magnitude of the extractive power varied in the following order: 6NHCl ? EDTA + NH₄OA_C, pH4.65 > DTPA‐TEA, pH 7.3. The mild extractants, EDTA and DTPA, gave the same order of removal of micronutrients being Zn < Cu < Fe < Mn. The acid extractant was on the contrast more effective on Cu and Fe with respect to Zn and Mn, respectively. Wheat concentrations of Zn, Mn and Fe were significantly correlated to soil micronutrients. Highly significant relationships were found for Zn extracted by DTPA solution (r = 0.737***) and for Mn and Fe extracted by EDTA solution (r = 0.710*** and r = 0.564**). Plant Zn and Mn were also well predicted by the acid extraction. The absence of correlation for plant Cu vs. soil Cu occurred probably because of wheat concentrations almost constant, ranging from 5.0 to 8.0 mg/kg.     

Seasonal levels of water‐extractable cations and anions in soil under blight‐affected and healthy citrus trees

Abstract

Soil samples were collected under blight‐affected and healthy citrus trees at 30‐day intervals for 24 months, at 20‐to 50‐cm depth. Analyses of water extracts (1:1 soil: water) for K, Ca, Mg, Na, SO₄, and Cl showed few differences in cations, but lower anion levels under blighted trees. The cation/anion ratio was significantly higher under blight‐affected trees. Samples collected once at different locations in the same time period showed the same differences. In one location, K was lower and Na higher under healthy trees than under blight‐affected trees, in others K was higher too.     

Relationship of ryegrass growth to extractable phosphorus in acidic soil amended with phosphate rock,coal combustion by‐product,limestone, and cellulose

Abstract

An improved management of phosphorus (P) is crucial for increasing crop production and improving environmental quality of acid infertile soils. Laboratory analyses and greenhouse experiments were conducted to evaluate effects of phosphate rock (PR), coal combustion by‐product (BP), limestone, and cellulose application on the relationship between soil test P and crop growth in acidic soil. Application of PR, BP, limestone, and cellulose increased soil pH, exchangeable calcium (Ca) and magnesium (Mg), and extractable P, and decreased free aluminum (Al) ion in the acid soil. Addition of BP or limestone increased P availability efficiency [PAE, mg dry matter yield (DMY) of plant per mg soil extractable P by Olsen‐P procedure] and P utilization efficiency (PUE, mg DMY of plant per mg P in the plant). There was significant positive correlation between the PAE and BP rates applied alone (r²=O.979, p<0.01) or with either PR (r²=0.972, p<0.01) or PR plus cellulose (r²=0.985, p<0.01). The PUE of ryegrass was significantly correlated with BP rates alone (r²=O.957, p<0.01) or with either PR (r²=0.906, p<0.01) or PR plus limestone (r²=O.699). The increase in PAE and PUE of ryegrass caused by BP and limestone reflected more plant root growth from increased availability of Ca and Mg and higher soil pH.     

Yield of iron‐sprayed and non‐sprayed strawberry cultivars grown on high ph calcareous soil

Abstract

Iron (Fe) deficiency chlorosis (FeDC) results in extensive reduction in yield of strawberry (Fragaria x ananassa Duch.) grown on high pH calcareous soils. Three cultivars differing in response to FeDC were grown on a high pH (8.2) calcareous soil (25.4% calcium carbonate equivalent in surface 20 cm) in the field (Choueifat, coastal area of Lebanon) to determine the effects of FeDC on fruit yield of cultivars sprayed with FeEDDHA [ferric ethylene‐diiminobis (2‐hydroxyphenyl) acetate]. The unsprayed plots were used as a control. No significant interaction (P<0.05) between cultivars x FeEDDHA spray treatment, and no significant differences (P<0.05) between one and two FeEDDHA spray(s)/week treatment was noted for visual FeDC, fruit number, and fruit yield. Sprayed cultivars once a week produced higher yields than unsprayed ones; overall increases were 33% (13% for ‘Motto’, 30% for ‘Chandler’, and 56% for ‘Douglas'). Even though only slight FeDC was noted on the ‘Motto’ cultivar receiving no Fe EDDHA spray, fruit yields were increased when sprayed with FeEDDHA. However, significant increases in yield for ‘Chandler’ and ‘Douglas’ cultivars with severe FeDC ratings were rioted when sprayed with FeEDDHA.     

Generation means analysis of traits related to lodging using two crosses of durum × emmer wheat

Genetic Resources and Crop Evolution - Lodging is one of the most important factors that affect wheat final yield. Emmer [Triticum turgidum subsp. dicoccum (Schrank ex Schübl.) Thell.] is a...