Zinc‐boron interaction effects in oilseed rape

The interaction effect of applied zinc (Zn) and boron (B) on early vegetative growth and uptake of Zn and B by two oilseed rape (canola) (Brassica napus L.) genotypes was investigated in a sand culture experiment under controlled environmental conditions. Two genotypes (Yickadee and Dunkeld) were grown at three Zn levels (0.05, 0.25, and 2.0 mg kg^‐1 soil) and two B levels (0.05 mg kg^‐1 soil and 0.5 mg kg^‐1 soil). Dunkeld produced significantly higher shoot and root dry matter than Yickadee at low Zn and low B supply indicating the superiority of Dunkeld over Yickadee for tolerance to both low Zn and low B supply. Chlorophyll content of fresh leaf tissue was increased significantly by an increase in Zn and B supply. Zinc deficiency enhanced B concentration in younger and older leaves. Boron concentration was higher in older leaves than in the younger leaves irrespective of B deficiency and sufficiency indicating immobility of B in two oilseed rape genotypes tested. Zinc concentration was higher in younger leaves than in the older leaves indicating mobility of Zn. An increased supply of Zn enhanced B uptake under high boron supply only. Zinc uptake in Dunkeld was enhanced significantly with an increased rate of B supply under high Zn supply, while the effect was not significant in Yickadee. Dunkeld proved to be more efficient in Zn and B uptake than Yickadee.     

Dissolution of slag fertilizers in a paddy soil and Si uptake by rice plant

Abstract

Maize (Zea mays L.) cv. Ganga 2 was grown in refined sand at three levels of copper: deficient (0.00065 mg L^-1), adequate (0.065 mg L^-1), and excess (6.5 mg L^-1), each at three levels, deficient (0.00065 mg L^-1), adequate (0.065 mg L^-1), and excess (6.5 mg L^-1) of zinc. Excess Cu magnified the zinc deficiency effects in maize by lowering further the biomass, the concentration of leaf Zn, activities of carbonic anhydrase, aldolase, and ribonuclease and intensified the visible foliar symptoms of Zn deficiency. The effects of Cu deficiency, low dry weight, the concentration of leaf Cu and activities of cytochrome oxidase and polyphenol oxidase were enhanced by excess Zn. Synergism was observed between combined deficiency of Cu and Zn and Cu or Zn deficiency, because the depression in the parameters characteristic of Cu or Zn deficiency was more pronounced when both Cu and Zn were deficient than when Cu or Zn was deficient. Antagonism was observed in some parameters between combined excess of Cu and Zn and Cu or Zn excess. Dry weight was decreased further when both Cu and Zn were in excess than when either Cu or Zn was in excess. After the infiltration of Cu and Zn together to the leaf discs from deficient Cu-deficient Zn treatment, the increase in the concentration of leaf Zn and the activities of aldolase, carbonic anhydrase, polyphenol oxidase, and cytochrome oxidase was more pronounced than after the infiltration of Cu or Zn singly. Discontinuance of excess Zn supply from the excess Zn-deficient Cu treatment increased the concentration of leaf Cu and activities of polyphenol oxidase and cytochrome oxidase and lowered the concentration of Zn. Similarly the discontinuance of excess Cu supply from the leaf discs in the “excess Cu-deficient Zn” treatment increased the leaf Zn concentration and the activities of carbonic anhydrase and aldolase.     

Varietal tolerance to Zinc deficiency in wheat and barley grown in chelatorbuffered nutrient solution and its effect on uptake of Cu,Fe, and Mn

Tolerance to zinc (Zn) deficiency was examined for three wheat (Triticum aestivum L.) and three barley (Hordeum vulgare L.) varieties grown in chelator‐buffered nutrient solution. Four indices were chosen to characterize tolerance to Zn deficiency: (1) relative shoot weight at low compared to high Zn supply (“Zn efficiency index”), (2) relative shoot to root ratio at low compared to high Zn supply, (3) total shoot uptake of Zn under deficient conditions, and (4) shoot dry weight under deficient conditions. Barley and wheat exhibited different tolerance to Zn deficiency, with barley being consistently more tolerant than wheat as assessed by all four indices. The tolerance to Zn deficiency in the barley varieties was in the order Thule=Tyra>Kinnan, and that of wheat in the order Bastian=Avle>Vinjett. The less tolerant varieties of both species accumulated more P in the shoots than the more tolerant varieties. For all varieties, the concentrations of Mn, Fe, Cu, and P in shoot tissue were negatively correlated with Zn supply. This antagonism was more pronounced for Mn and P than for Cu and Fe. Accumulation of Cu in barley roots was extremely high under Zn‐deficient conditions, an effect not so clearly indicated in wheat.     

INFLUENCE OF IRON-CHELATES ON TRACE ELEMENT UPTAKE FROM TWO CALCAREOUS SOILS AND THE ACTIVITY OF OXYGEN-SCAVENGING ENZYMES IN LETTUCE

A pot experiment was carried out to determine the ability of lettuce (Lactuca sativa cv. ‘Waldmann's dark green’) to acquire iron (Fe) from Fe-ethylenediaminedisuccinic acid [EDDS, both as an isomeric mixture, EDDS(mix), and (S,S)-EDDS], Fe-ethylenediaminetetraacetic acid (EDTA) and Fe-ethylenediimonobis(2-hydroxyphenyl)acetic acid (EDDHA) in two calcareous soils and consequent effect on the activity of reactive oxygen species scavenging enzymes. Probably due to the rapid biodegradation of [S,S]-EDDS, EDDS(mix) provided Fe to lettuce more efficiently. Iron-EDDS(mix) and Fe-EDDHA were equally efficient in increasing Fe concentration in lettuce. The activity of superoxide dismutase (SOD) was not affected by Fe deficiency and the activity of copper (Cu) and zinc (Zn) containing SOD (Cu/ZnSOD) was dependent on lettuce Zn concentration. Ascorbate peroxidase and guaiacol peroxidase activities were increased by Fe-EDDHA, probably due to the steady supply of Fe. Physiologically active Fe pool for lettuce was equally provided by Fe-EDDS(mix) and Fe-EDTA.     

Growth,Mineral Composition,and Biochemical Changes of Broad Bean as Affected by Sodium Chloride and Zinc Levels and Sources

Plants grown in salt‐affected soils may suffer from limited available water, ion toxicity, and essential plant nutrient deficiency, leading to reduced growth. The present experiment was initiated to evaluate how salinity and soil zinc (Zn) fertilization would affects growth and chemical and biochemical composition of broad bean grown in a calcareous soil low in available Zn. The broad bean was subjected to five sodium chloride (NaCl) levels (0, 10, 20, 30, and 40 m mol kg^?1 soil) and three Zn rates [0, 5, and 10 mg kg^?1 as Zn sulfate (ZnSO₄) or Zn ethylenediaminetetraaceticacid (EDTA)] under greenhouse conditions. The experiment was arranged in a factorial manner in a completely randomized design with three replications. Sodium chloride significantly decreased shoot dry weight, leaf area, and chlorophyll concentration, whereas Zn treatment strongly increased these plant growth parameters. The suppressing effect of soil salinity on the shoot dry weight and leaf area were alleviated by soil Zn fertilization, but the stimulating effect became less pronounced at higher NaCl levels. Moreover, rice seedlings treated with ZnSO₄ produced more shoot dry weight and had greater leaf area and chlorophyll concentration than those treated with Zn EDTA. In the present study, plant chloride and sodium accumulations were significantly increased and those of potassium (K), calcium (Ca), and magnesium (Mg) strongly decreased as NaCl concentrations in the soil were increased. Moreover, changes in rice shoot Cl^?, Na⁺, and K⁺ concentrations were primarily affected by the changes in NaCl rate and to a lesser degree were related to Zn levels. The concentrations of Cl^? and Na⁺ associated with 50% shoot growth suppression were greater with Zn‐treated plants than untreated ones, suggesting that Zn fertilization might increase the plant tolerance to high Cl^? and Na⁺ accumulations in rice shoot. Zinc application markedly increased Zn concentration of broad bean shoots, whereas plants grown on NaCl‐treated soil contained significantly less Zn than those grown on NaCl‐untreated soil. Our study showed a consistent increase in praline content and a significant decrease in reducing sugar concentration with increasing salinity and Zn rates. However, Zn‐treated broad bean contained less proline and reducing sugars than Zn‐untreated plants, and the depressing impact of applied Zn as Zn EDTA on reducing sugar concentration was greater than that of ZnSO₄. In conclusion, it appears that when broad bean is to be grown in salt‐affected soils, it is highly advisable to supply plants with adequate available Zn.     

Zinc nutrition affects alfalfa responses to water stress and excessive moisture

The interactive effect of applied zinc (Zn) and soil moisture on early vegetative growth of three alfalfa (lucerne) (Medicago sativa L.) varieties was investigated in a sand‐culture pot experiment to test whether there is link between Zn nutrition and soil moisture stress or excessive moisture tolerance in alfalfa plants. Three varieties (Sceptre, Pioneer L 69, and Hunterfield) with differential Zn efficiency (ability of a variety to grow and yield well in a Zn deficient soil is called a Zn‐efficient variety) were grown at two Zn levels (low Zn supply: 0.05 mg Zn kg^‐1 of soil, adequate Zn supply: 2.0 mg Zn kg^‐1 of soil) and three levels of soil moisture (soil moisture stress: 3% soil moisture on soil dry weight basis; adequate soil moisture: 12% soil moisture on soil dry weight basis; excessive soil moisture: 18% soil moisture on soil dry weight basis) in a Zn deficient (DTPA Zn: 0.06 mg kg^‐1 soil) siliceous sand. Zinc treatments were applied at planting, while soil moisture treatments were applied three weeks after planting and continued for two weeks. Plants were grown in pots under controlled temperature conditions (20°C, 12 h day length; 15°C, 12 h night cycle) in a glasshouse. Plants grown at low Zn supply developed Zn deficiency symptoms, and there was a severe solute leakage from the leaves of Zn‐deficient plants. Adequate Zn supply significantly enhanced the leaf area, leaf to stem ratio, biomass production of shoots, and roots, succulence of plants and Zn concentration in leaves. At low Zn supply, soil moisture stress and excessive moisture treatments significantly depressed the shoot dry matter, leaf area and leaf to stem ratio of alfalfa plants, while there was little impact of soil moisture treatments when supplied Zn concentration was high. The detrimental effects of soil moisture stress and excessive soil moisture under low Zn supply were less pronounced in Sceptre, a Zn‐efficient alfalfa variety compared with Hunterfield, a Zn‐inefficient variety. Results suggest that the ability of alfalfa plants to cope with water stress and excessive soil moisture during early vegetative stage was enhanced with adequate Zn nutrition.     

Zinc uptake kinetics in the low and high‐affinity systems of two contrasting rice genotypes

Rice (Oryza sativa L.) cultivars differ widely in their susceptibility to zinc (Zn) deficiency. The physiological basis of Zn efficiency (ZE) is not clearly understood. In this study, the effects of Zn‐sufficient and Zn‐deficient pretreatments on the time and concentration‐dependent uptake kinetics of Zn were examined at low (0–160 nM) and high Zn supply levels (0–80 μM) in two contrasting rice genotypes (Zn‐efficient IR36 and Zn‐inefficient IR26). The results show that ⁶⁵Zn²⁺ influx rate was over 10 times greater for the Zn‐deficient pretreatment plants than for the Zn‐sufficient pretreatment plants. At low Zn supply, significant higher ⁶⁵Zn²⁺ influx rates were found for the Zn‐efficient genotype than for the inefficient genotype, with a greater difference (over three‐fold) at Zn supply > 80 nM in the Zn‐deficient pretreatments. At high Zn supply levels, however, a difference (2.5‐fold) in ⁶⁵Zn²⁺ influx rate between the two genotypes was only noted in the Zn‐deficient pretreatments. Similarly, the ⁶⁵Zn²⁺ accumulation in the roots and shoots of Zn‐efficient IR36 pretreated with Zn‐deficiency were sharply increased with time and higher than that in the Zn‐inefficient IR26 with an over four‐fold difference at 2 h absorption time. However, with Zn‐deficient pretreatments, the Zn‐efficient genotype showed a higher shoot : root ⁶⁵Zn ratio at higher Zn supply. Remarkable differences in root and shoot ⁶⁵Zn²⁺ accumulation were noted between the two genotypes in the Zn‐deficiency pretreatment, especially at low Zn level (0.05 μM), with 2–3 times higher values for IR36 than for IR26 at an uptake time of 120 min. There appear to be two separate Zn transport systems mediating the low and high‐affinity Zn influx in the efficient genotype. The low‐affinity system showed apparent Michaelis–Menten rate constant (K_m) values ranging from 10 to 20 nM, while the high‐affinity uptake system showed apparent K_m values ranging from 6 to 20 μM. The V_max value was significantly elevated in IR36 and was 3–4‐fold greater for IR36 than for IR26 at low Zn levels, indicating that the number of root plasma membrane transporters in low‐affinity uptake systems play an important role for the Zn efficiency of rice.     

不同供Zn量对三种小麦基因型幼苗生长和养分吸收的影响

采用溶液培养方法,研究了不同供Zn量(0、0.5、104、0.mg/L,分别用Zn0、Zn0.5、Zn10、Zn40表示)对三种亲缘关系很远的半冬性小麦基因型郑麦9023、陕512、西农979幼苗生长发育及Zn、Fe、Mn吸收的影响,以期为筛选耐高锌的小麦基因型提供理论依据。结果表明,不供Zn时小麦幼苗未出现缺Zn症状;Zn0.5对小麦的正常生长影响较小。三种基因型小麦的幼苗在过量供Zn(Zn10、Zn40)时均受到严重伤害:抑制小麦分蘖、根系及地上部生长,叶片叶绿素SPAD值显著降低,小麦植株尤其是根部的耐性指数降低;施入的Zn的转运率显著降低,却大大提高了小麦植株尤其是根部的Zn含量和吸收量,但Zn10时幼苗体内Zn含量和吸收量大于Zn40,且Zn10比Zn40更能在根部积累Zn。Zn与Fe的吸收在根部似乎表现为互助作用,而地上部表现为颉颃作用;Zn与Mn之间表现出强烈的颉颃作用。过量供Zn时以西农979耐性指数最大,Zn转运率最高,植株体内的Fe、Mn含量也高。总之,供Zn量为通常配方的51～0倍时对小麦幼苗的生长尚无明显影响;1002～00和4008～00倍时则能对小麦幼苗造成严重伤害,三种供试小麦基因型中以西农979对过量Zn毒害的耐性最强。     

Effect of Pyrite Application on Wheat-Maize Growth and Nutrient Uptake Under Diverse Soil Conditions

Zinc (Zn) and phosphorus (P) deficiency is a common nutritional problem for the production of many crops in semi-arid Mediterranean region of Turkey. This problem results in the application of increasing amounts of fertilizers. Minerals (such as pyrite) including iron (Fe) and sulfur (S) can decrease soil pH may be a critical factor in crop production under low supply of Zn and P in calcareous and clay soils. The aim of this research was to determine the effect of pyrite application on wheat-maize-wheat growth, P and Zn concentration with three successive pot experiments. Bread (Seri-82) (Triticum durum L.) durum (Kunduru) wheat (Triticum aestivum L.), and maize (Zea mays L.) RX 788 hybrid was grown in Zn and P-deficient calcareous soils from Central Anatolian Sultanönü and Çukurova Karaburun. Plants were grown under greenhouse conditions at five rates of pyrite (0, 0.5, 1, 1.5, and 2 g pyrite kg^?1 soil) in three consecutive experiments. Pyrite application increased shoot dry matter production of wheat and maize. With time effect of pyrite on plant growth and nutrient uptake was more. In accordance with growth data, pyrite application enhanced P and Zn concentration of plants, especially under Zn deficient Sultanönü soil then Karaburun soil. Plants grown in Karaburun soil had more P and Zn concentration than grown in Sultanönü soil. The results obtained indicate that pyrite can be used as a zinc fertilizer sources for gramine plants such as wheat and maize.     

DO MAIZE AND PEPPER PLANTS DEPEND ON MYCORRHIZAE IN TERMS OF PHOSPHORUS AND ZINC UPTAKE?

Nutrient deficiency, especially zinc (Zn) and phosphorus (P), is a common nutritional problem for the production of some crops in Turkey. This problem results in the application of increasing amounts of several fertilizers. Mycorrhizal inoculation or the indigenous potential of mycorrhizae in the soil is a critical factor in crop production under low supply of Zn and P. The effects of selected mycorrhizal inoculation on growth and Zn and P uptake of maize and green pepper were investigated in Zn- and P-deficient calcareous soils from Central Anatolia. Soils were sterilized by autoclaving and plants were grown for 7 weeks in pots under greenhouse conditions with inoculation of two selected arbuscular mycorrhizal (AM) species (Glommus moseea and G. etunicatum) at three rates of P (0, 25, 125 mg P kg^?1 soil) and two rates of Zn (0 and 5 mg Zn kg^?1soil). Without mycorrhizal inoculation, shoot and root dry matter production were severely affected by P and Zn deficiencies, and supply of adequate amounts of P and Zn significantly enhanced plant growth. When the soil was inoculated with mycorrhizal inoculation, the increasing effects of P and Zn fertilization on plant growth remained less pronounced. In accordance with growth data, mycorrhizae inoculation enhanced P and Zn concentration of plants, especially under low supply of P and Zn. The results obtained indicate that maize and green pepper are highly mycorrizal–dependent (MD) plant species under both low P and Zn supply and mycorrhizae play an essential role in P and Zn nutrition of plants in P and Zn-deficient soils. Although addition of P and Zn increased plant growth and plants are mycorrhizal dependent on P and Zn nutrition however dependence is much more dependent on P nutrition.     

Diagnosis of zinc deficiency in peanut (Arachis hypogaea L.) by plant analysis

Abstract

Critical values of zinc (Zn) concentration in young leaves Here established for the diagnosis of Zn deficiency in peanut by examining the relationship of Zn concentration in leaves to shoot dry matter (DM) at two growth stages of plants grown in pots of Zn deficient sand at seven levels of Zn supply (0, 67, 133, 200 267, 533, and 1067 μg Zn/kg soil). Zinc deficient peanut accumulated reddish pigments in stems, petioles and leaf veins in addition to the more common symptoms of Zn deficiency in plants. Zinc concentrations increased with increasing Zn supply in the blades of the youngest fully expanded leaf (YFEL) and in the blades of the leaves immediately older (YFEL+1) and younger (YFEL‐1) than it: they also increased with increasing Zn supply in the petioles of the YFEL+1 and YFEL and in the basal stem internode but their Zn concentrations Here always much lower than those in the blades. Critical Zn concentrations in the blades of the YFEL and YFEL+1 Here 8–10 mg Zn/kg DM at early pegging and mid pod filling: values for YFEL‐1 were similar but more variable. The blade of the YFEL is recommended for diagnosis of Zn deficiency in peanut and 8–10 mg Zn/kg DM as its critical value.     

Differences in shoot growth and zinc concentration of 164 bread wheat genotypes in a zinc‐deficient calcareous soil

Abstract

A greenhouse experiment was carried out to study severity of the zinc (Zn) deficiency symptoms on leaves, shoot dry weight and shoot content and concentration of Zn in 164 winter type bread wheat genotypes (Triticunt aestivum L.) grown in a Zn‐deficient calcareous soil with (+Zn=10 mg Zn kg^?1 soil) and without (‐Zn) Zn supply for 45 days. Tolerance of the genotypes to Zn deficiency was ranked based on the relative shoot growth (Zn efficiency ratio), calculated as the ratio of the shoot dry weight produced under Zn deficiency to that produced under adequate Zn supply. There was a substantial difference in genotypic tolerance to Zn deficiency. Among the 164 genotypes, 108 genotypes had severe visible symptoms of Zn deficiency (whitish‐brown necrotic patches) on leaves, while in 25 genotypes Zn deficiency symptoms were slight or absent, and the remaining genotypes (e.g., 31 genotypes) showed mild deficiency symptoms. Generally, the genotypes with higher tolerance to Zn deficiency originated from Balkan countries and Turkey, while genotypes originating from the breeding programs in the Great Plains of the United States were mostly sensitive to Zn deficiency. Among the 164 wheat genotypes, Zn efficiency ratio varied from 0.33 to 0.77. The differences in tolerance to Zn deficiency were totally independent of shoot Zn concentrations, but showed a close relationship to the total amount (content) of Zn per shoot. The absolute shoot growth of the genotypes under Zn deficiency corresponded very well with the differences in tolerance to Zn deficiency. Under adequate Zn supply, the 10 most Zn‐ inefficient genotypes and the 10 most Zn‐efficient genotypes were very similar in their shoot dry weight. However, under Zn deficiency, shoot dry weight of the Zn‐efficient genotypes was, on average, 1.6‐fold higher compared to the Zn‐inefficient genotypes. The results of this study show large, exploitable genotypic variation for tolerance to Zn deficiency in bread wheat. Based on this data, total amount of Zn per shoot, absolute shoot growth under Zn deficiency, and relative shoot growth can be used as reliable plant parameters for assessing genotypic variation in tolerance to Zn deficiency in bread wheat.     

Biofortification of Durum Wheat with Zinc Through Soil and Foliar Applications of Nitrogen

Increasing zinc (Zn) concentration of cereal grains is a global challenge to alleviate Zn deficiency‐related health problems in humans caused by low dietary Zn intake. This study investigated the effects of soil‐ and foliar‐applied nitrogen (N) and Zn fertilizers on grain Zn accumulation of durum wheat (Triticum durum) grown on a Zn‐deficient soil. In addition, localization of Zn and protein within durum wheat grain was studied by using Bradford reagent for protein and dithizone (diphenyl thiocarbazone) for Zn. Grain Zn concentration was greatly enhanced by soil or foliar applications of Zn. When Zn supply was adequately high, both soil and foliar N applications improved grain Zn concentration. Consequently, there was a significant positive correlation between grain concentrations of Zn and N, when Zn supply was not limiting. Protein and Zn staining studies showed co‐localization of Zn and protein within grain, particularly in the embryo and aleurone. Results indicate that N and Zn fertilization have a synergistic effect on grain Zn concentration. Possibly, increasing N supply contributes to grain Zn concentration by affecting the levels of Zn‐chelating nitrogenous compounds or the abundance of Zn transporters. Our results suggest that nitrogen management can be an effective agronomic tool to improve grain Zn concentration.     

Morphology and physiology of zinc‐stressed mulberry plants

The aim of this study was to induce symptoms of zinc deficiency and Zn excess and to relate the generation of reactive oxygen species (ROS) and the altered cellular redox environment to the effects of Zn stress in mulberry (Morus alba L.) cv. Kanva‐2 plants. The antioxidative responses of Zn‐stressed mulberry plants were studied by determining malondialdehyde content (MDA, a measure of lipid peroxidation) as indicator of oxidative damage and the ratio of dehydroascorbate (DHA) to ascorbic acid (AsA) as an index of the cellular redox state. The Zn‐deficiency effects appeared as faint paling and upward cupping of the young emerging leaves. The paling intensified with time, and affected leaves finally developed necrotic spots. At advanced stage of Zn deficiency, newly emerged leaves were spindle‐shaped, pale, and small in size. Apart from their stunted appearance, the plants supplied excess Zn did not show any specific visible symptom. Leaf water status of mulberry plant was affected in Zn‐stressed plants. Deficient leaves had decreased water potential (Ψ) and specific water content (SWC), contained less tissue Zn, less chloroplastic pigments, and high tissue Fe and Mn concentrations. However, excess supply of Zn was found to increase Ψ and decrease tissue Fe. Both hydrogen peroxide and MDA accumulated in leaves of Zn‐stressed plants. While the concentration of DHA did not vary in Zn‐deficient leaves, it was increased in leaves of plants supplied excess Zn. The ratio of the redox couple (DHA to AsA) was increased both in Zn‐deficient or Zn‐excess plants. The activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7), and ascorbate peroxidase (EC 1.11.1.11) increased in Zn‐stressed plants. The results suggest that deficiency or excess of Zn aggravates oxidative stress through enhanced generation of ROS and a disturbed redox homeostasis in mulberry plants.     

Influence of Gyttja on Shoot Growth and Shoot Concentrations of Zinc and Boron of Wheat Cultivars Grown on Zinc‐Deficient and Boron‐Toxic Soil

Abstract

Greenhouse experiments were carried out to study the influence of gyttja, a sedimentary peat, on the shoot dry weight and shoot concentrations of zinc (Zn) and boron (B) in one bread wheat (Triticum aestivum L., cv. Bezostaja) and one durum wheat (Triticum durum L., cv. Kiziltan) cultivar. Plants were grown in a Zn‐deficient (DTPA‐Zn: 0.09 mg kg^?1 soil) and B‐toxic soil (CaCl₂/mannitol‐extractable B: 10.5 mg kg^?1 soil) with (+Zn = 5 mg Zn kg^?1 soil) and without (?Zn = 0) Zn supply for 55 days. Gyttja containing 545 g kg^?1 organic matter was applied to the soil at the rates of 0, 1, 2.5, 5, and 10% (w/w). When Zn and gyttja were not added, plants showed leaf symptoms of Zn deficiency and B toxicity, and had a reduced growth. With increased rates of gyttja application, shoot growth of both cultivars was significantly enhanced under Zn deficiency, but not at sufficient supply of Zn. The adverse effects of Zn deficiency and B toxicity on shoot dry matter production became very minimal at the highest rate of gyttja application. Increases in gyttja application significantly enhanced shoot concentrations of Zn in plants grown without addition of inorganic Zn. In Zn‐sufficient plants, the gyttja application up to 5% (w/w) did not affect Zn concentration in shoots, but at the highest rate of gyttja application there was a clear decrease in shoot Zn concentration. Irrespective of Zn supply, the gyttja application strongly decreased shoot concentration of B in plants, particularly in durum wheat. For example, in Zn‐deficient Kiziltan shoot concentration of B was reduced from 385 mg kg^?1 to 214 mg kg^?1 with an increased gyttja application. The results obtained indicate that gyttja is a useful organic material improving Zn nutrition of plants in Zn‐deficient soils and alleviating adverse effects of B toxicity on plant growth. The beneficial effects of gyttja on plant growth in the Zn‐deficient and B‐toxic soil were discussed in terms of increases in plant available concentration of Zn in soil and reduction of B uptake due to formation of tightly bound complexes of B with gyttja.     

Effects of sulfur supply on soybean plants exposed to zinc toxicity

Application of most waste or by‐product material increases the zinc (Zn) concentration in soils markedly. This investigation was conducted to determine if enhanced sulfur (S) supplied as sulfate (SO₄) would modify the toxic effects of excess Zn. Soybean (Glycine max [L.] Merf. cv. Rarisorri) was grown for two weeks in nutrient solutions containing ranges in Zn (0.8 to 80 μM) and S (0.02 to 20 mM). Root and shoot conditions were observed, dry weights measured, and Zri concentration determined. Zinc‐toxicity symptoms started about one week after transplanting young plants to nutrient solutions. Symptoms including chlorosis, especially in the trifoliate leaves, and change in orientation of unifoliate leaves were mild in 20 μM‐, intermediate in 40 μM‐, and severe in 80 μM Zn‐containing solutions. Dry weight was reduced in plants exposed to 20, 40, and 80 μM Zn. Plants grown in 40 μM Zn and 20 mM S survived longer than those grown in lower S concentrations and showed alleviation of the chlorosis in trifoliate leaves. The change in the orientation of the unifoliate leaves due to Zn toxicity, however, was not affected by S. Zinc contents in shoots grown at toxic Zn levels were higher in 20 mM‐ than in lower S‐containing nutrient solutions. High S supply (20 mM) increased Zn translocation from roots to shoots. Besides increasing the Zn translocation from roots to shoots, it seems that S nutrition may also be a factor helping the plants to cope with high levels of Zn in their tissues.     

螯合–缓冲营养液培养条件下添加外源锌对小麦幼苗生长和TaZIPs基因表达的影响

[目的]研究外源供锌对小麦幼苗根系发育、光合作用、金属离子平衡以及锌铁转运蛋白ZIP基因的表达,以期深入了解小麦的锌营养作用机理.[方法]采用水培试验方法,供试材料为冬小麦'百农207',试验共设置了5个锌(Zn)浓度处理:0?(Zn0)、0.05?(Zn0.05)、0.25?(Zn0.25)、1.0?(Zn1.0)和...     

不同水分状况下施锌对玉米生长和锌吸收的影响

选择潮土(砂壤)和土(粘壤)两种质地不同的土壤,进行盆栽试验,研究不同土壤水分条件下施锌对玉米生长和锌吸收的影响。结果表明,施锌显著增加了玉米植株根、茎、叶以及整株干物质重;缺锌条件下玉米植株根冠比、根叶比和根茎比趋向增大。施锌显著提高了玉米植株各器官中锌的浓度和吸收量,并明显促进锌向地上部运移。干旱胁迫抑制了玉米植株生长,根冠比、根茎比、根叶比增大;随着土壤水分供应增加,植株生长加快,各器官生物量以茎和叶增加大于根。水分胁迫下,在潮土上玉米叶片中锌浓度上升;在土上叶片中锌浓度下降。但增施锌后,根和茎锌浓度增加幅度较大,叶片增加幅度较小;施锌和水分胁迫对根和茎锌浓度的交互作用极显著。水分胁迫下,玉米植株对锌的吸收总量减少。水分胁迫和锌肥施用对玉米叶片、茎锌吸收量的交互作用十分显著,但对根锌吸收量的交互影响不显著。     

Zinc deficiency alters soybean susceptibility to pathogens and pests

Inadequate plant nutrition and biotic stress are key threats to current and future crop yields. Zinc (Zn) deficiency and toxicity in major crop plants have been documented, but there is limited information on how pathogen and pest damage may be affected by differing plant Zn levels. In our study, we used soybean plants as a host, a soybean pest, and three soybean pathogens to determine whether plant Zn levels change pest and disease assessments. Two soybean cultivars were grown in sand culture with a soluble nutrient solution that ranged from Zn‐deficient to toxic. Detached leaves from these plants were either inoculated with Aphis glycines, the soybean aphid, Xanthomonas axonopodis pv. glycines, a bacterium that causes bacterial pustule, Sclerotinia sclerotiorum, the necrotrophic fungus responsible for stem rot, or Phakopsora pachyrhizi, a biotrophic obligate pathogen that causes soybean rust. There were significant (P < 5%) effects on aphid colonization, positive counts for bacterial pustule, S. sclerotiorum leaf area affected, and numbers of rust lesions associated with the Zn treatments. Plants grown with the physiologically optimal levels of Zn (2 µM) had less (P < 5%) soybean aphids cm^?2 leaflet than plants grown without Zn, at 0.1× Zn (0.2 µM), or at 100× Zn fertilization (200 µM). Plants grown with the normal fertilization of Zn or 100× Zn had fewer (P < 5%) positive counts for bacterial pustule and less lesion area affected by S. sclerotiorum than plants grown without Zn or fertilized with 0.1× Zn. For soybean rust, plants grown with the physiologically optimal fertilization of Zn or 100× Zn had higher (P < 5%) lesions cm^?2 on leaflets from plants grown without Zn or fertilized with 0.1× Zn. These results indicate different Zn nutrition levels in soybean significantly affected aphid and disease development.     

Nutritional Alleviation of Zinc-Induced Iron Deficiency in Indian Mustard and the Effects on Zinc Phytoremediation

ABSTRACT

Indian mustard (Brassica juncea Czern) is a promising species for the phytoextraction of zinc (Zn), but the effectiveness of this plant can be limited by iron (Fe) deficiency under Zn-contaminated conditions. Our objectives were to determine the effects of root-applied Fe and Zn on plant growth, accumulation of Zn in plant tissues, and development of nutrient deficiencies for B. juncea. In the experiment, B. juncea was supplied 6 levels of iron ethylenediamine dihydroxyphenylacetic acid (Fe-EDDHA; 0.625 to 10.0 mg L^?1) and two levels of Zn (2.0 and 4.0 mg L^?1) for 3 weeks in a solution-culture experiment. Nutrient solution pH decreased with decreasing supply of Fe and increasing supply of Zn in solution, indicating that B. juncea may be an Fe-efficient plant. If plants were supplied 2.0 mg Zn L^?1, plant growth was stimulated by increases in Fe supply, but plant growth was not influenced by Fe treatments if plants were supplied 4.0 mg Zn L^?1. Zinc concentration in roots and shoots was suppressed by increasing levels of Fe in solution. Leaf concentrations of Cu, Mn, and P were suppressed also as Fe supply in solutions increased. Iron additions to the nutrient solution were not effective at increasing the Zn-accumulation potential of B. juncea unless plants were supplied the higher level of Zn in solution culture. Even under these conditions, Fe additions were effective only if supplied at low levels in solution culture (1.25 mg Fe L^?1). Results suggest that Fe fertility has limited potential for enhancing Zn phytoextraction by B. juncea, even if plants suffer a suppression in growth from Fe deficiency.