Volvariella-treated Eucalyptus sawdust stimulates wheat and onion growth

Conversion of sawdust, a major waste generated by the timber industry, to an agricultural supplement was explored. Beds made with a mixture of Eucalyptus sawdust and soil reduced the chlorophyll content and the growth rate of wheat seedlings. However, following treatment with Volvariella volvaceae and urea, the sawdust in growth beds enhanced both the chlorophyll content and growth of wheat seedlings. Application of treated sawdust to soil increased the biomass of both bulb and foliage of onion. This represents a small beginning in the conversion of an industrial solid waste into a soil conditioner for enhancing agricultural productivity.     

Silicon Improves the Tolerance of Wheat Seedlings to Ultraviolet-B Stress

Enhanced ultraviolet-B (UV-B) irradiation is one of the most important abiotic stresses that could influence the growth and physiological traits of plants. In this work, we reported the effects of silicon on the growth and physiological characteristics of wheat seedlings (Triticum aestivum L. cv Hengmai5229) subject to UV-B stress. Treatments with silicon significantly increased total biomass and chlorophyll (a + b) content, and reduced malondialdehyde (MDA) content and the rate of superoxide radical (O₂⁻) production in wheat seedlings subjected to UV-B stress. Silicon treatments also induced an increased in soluble sugar, anthocyanins, and flavonoid content. Leaf silicon concentration increased with the increasing of silicon supply to soil. Positive correlations were found in leaf silicon concentration with total biomass, chlorophyll (a + b), proline, and soluble protein content, respectively. MDA content and the rate of O₂⁻ production were negatively correlated with leaf silicon concentration in seedlings. The results demonstrated that silicon alleviated the damage caused by UV-B on wheat seedlings to some extent by the increase in antioxidant compounds content and leaf silicon concentration.     

Effects of Selenium on Wheat Seedlings Under Drought Stress

The paper reports the effects of selenium (Se) supply on growth and some physiological traits of wheat (Triticum aestivum L. cv Shijiazhuang NO. 8) seedlings exposed to drought stress. The growth and physiological responses of seedlings were different depending on the Se concentration. The higher (3.0 mg Se kg⁻¹) and lower amount used (0.5 mg Se kg⁻¹) did not significantly affect on biomass accumulation. Treatments with 1.0 and 2.0 mg Se kg⁻¹ promoted biomass accumulation of wheat seedlings. Treatments at 1.0, 2.0, and 3.0 mg Se kg⁻¹ significantly increased root activity, proline content, peroxidase (POD), and catalase (CAT) activities, carotenoids (Car) content, chlorophyll content, and reduced malondialdehyde (MDA) content of wheat seedlings. Lower Se treatment did not significantly effect on chlorophyll content and MDA content, although it also increased some antioxidant index (proline and Car content, POD and CAT activities) in wheat seedlings. These results suggest that optimal Se supply is favorable for growth of wheat seedlings during drought condition.     

Evaluation of different lignocellulosic substrates for the production of cellulases and xylanases by the basidiomycete fungi <Emphasis Type="Italic">Bjerkandera adusta</Emphasis> and <Emphasis Type="Italic">Pycnoporus sanguineus</Emphasis>

Agricultural waste products are potential resources for the production of a number of industrial compounds, including biofuels. Basidiomycete fungi display a battery of hydrolytic enzymes with prospective use in lignocellulosic biomass transformation, however little work has been done regarding the characterization of such activities. Growth in several lignocellulosic substrates (oak and cedar sawdust, rice husk, corn stubble, wheat straw and Jatropha seed husk) and the production of cellulases and xylanases by two basidiomycete fungi: Bjerkandera adusta and Pycnoporus sanguineus were analyzed. Growth for P. sanguineus was best in rice husk while corn stubble supported the highest growth rate for B. adusta. Among the substrates tested, cedar sawdust produced the highest cellulolytic activities in both fungal species, followed by oak sawdust and wheat straw. Xylanolytic activity was best in oak and cedar sawdust for both species. We found no correlation between growth and enzyme production. Zymogram analysis of xylanases and cellulases showed that growth in different substrates produced particular combinations of protein bands with hydrolytic activity.     

Cadmium stress in wheat seedlings: growth,cadmium accumulation and photosynthesis

Seedlings of wheat (Triticum aestivum L.) cultivars Jing 411, Jinmai 30 and Yangmai 10 were exposed to 0, 10, 20, 30, 40 or 50 μM of CdCl₂ in a solution culture experiment. The effects of cadmium (Cd) stress on wheat growth, leaf photon energy conversion, gas exchange, and Cd accumulation in wheat seedlings were investigated. Gas exchange was monitored at 3, 9, 24 days after treatment (DAT). Growth parameters, chlorophyll content, leaf chlorophyll fluorescence, and Cd concentration in shoot and root were measured at 24 DAT. Seedling growth, gas exchange, chlorophyll content, chlorophyll fluorescence parameters were generally depressed by Cd stress, especially under the high Cd concentrations. Cd concentration and accumulation in both shoots and roots increased with increasing external Cd concentrations. Relationships between corrected parameters of growth, photosynthesis and fluorescence and corrected Cd concentrations in shoots and roots could be explained by the regression model Y = K/(1 + exp(a + bX)). Jing 411 was found to be Cd tolerant considering parameters of chlorophyll content, photosynthesis and chlorophyll fluorescence in which less Cd translocation was from roots into shoots. The high Cd concentrations were in shoots and roots in Yangmai 10 which has been found to be a relative Cd tolerant cultivar in terms of most growth parameters.     

Zinc Extraction potential of two common crop plants,Nicotiana tabacum and Zea mays

White spruce [Picea glauca (Moench) Voss] seedlings were inoculated with Hebeloma crustuliniforme and treated with 25 mM NaCl to examine the effects of salinized soil and mycorrhizae on root hydraulic conductance and growth. Mycorrhizal seedlings had significantly greater shoot and root dry weights, number of lateral branches and chlorophyll content than non-mycorrhizal seedlings. Salt treatment reduced seedling growth in both non-mycorrhizal and mycorrhizal seedlings. However, needles of salt-treated mycorrhizal seedlings had several-fold higher needle chlorophyll content than that in non-mycorrhizal seedlings treated with salt. Mycorrhizae increased N and P concentrations in seedlings. Na levels in shoots and roots of salt-treated mycorrhizal seedlings were significantly lower and root hydraulic conductance was several-fold higher than in non-mycorrhizal seedlings. A reduction of about 50% in root hydraulic conductance of mycorrhizal seedlings was observed after removal of the fungal hyphal sheath. Transpiration and root respiration rates were reduced by salt treatments in both groups of seedlings compared with the controls, however, both transpiration and respiration rates of salt-treated mycorrhizal seedlings were as high as those in the non-mycorrhizal seedlings that had not been subjected to salt treatment. The reduction of shoot Na uptake while increasing N and P absorption and maintaining high transpiration rates and root hydraulic conductance may be important resistance mechanisms in ectomycorrhizal plants growing in salinized soil.     

Effect of osmotic stress and sodium nitroprusside pretreatment on proline metabolism of wheat seedlings

Effect of osmotic stress and sodium nitroprusside (SNP, NO donor) pretreatment on growth and proline metabolism of wheat seedlings was investigated. Polyethylene glycol 6000 treatment for 2, 4 and 6 d could be termed as mild, moderate and severe stress, respectively, according to decrease in the relative water content. Severe osmotic stress significantly decreased the growth and photochemical efficiency, and increased proline content due to activation of its synthesis. 0.2 mM SNP pretreatment enhanced growth of wheat seedlings, increased variable to maximum fluorescence ratio (F_v/F_m) and fluorescence yield, while decreased proline content. However, 2 mM SNP retarded the seedlings growth and chlorophyll a fluorescence, and increased proline accumulation. Our results showed that NO might be involved in the regulation of osmotic stress in a concentration-dependent manner.     

Responses of Wheat Seedlings to Exogenous Selenium Supply Under Cold Stress

Dose-dependent effects of selenium on growth and physiological trait of wheat seedlings (Triticum aestivum L. cv Han NO.7086) exposed to cold stress are reported. Responses of seedlings were different depending on the Se concentration. The treatments with 0.5 and 1.0 mg Se kg⁻¹ significantly increased biomass and chlorophyll content of seedlings. However, the treatments at 2.0 and 3.0 mg Se kg⁻¹ only induced an evident increase in chlorophyll content and did not promote biomass accumulation of seedlings. Antioxidant compounds content (anthocyanins, flavonoids, and phenolic compounds) and antioxidant enzymes’ activities (peroxidase and catalase) increased by different Se treatments, while only the treatment with 1.0 mg Se kg⁻¹ induced a significant reduce in malondialdehyde content and the rate of superoxide radical production of wheat seedlings. The results of this study demonstrated that Se supply could increase antioxidant capacity of seedlings, and optimal Se supply reduced production of free radicals, membrane lipid peroxidation, and promoted biomass accumulation.     

Protective role of selenium in wheat seedlings subjected to enhanced UV-B radiation

Selenium (Se) is beneficial for some plants and is able to increase resistance and antioxidant capacity of plants subjected to stressful environment. In this work, the effects of enhanced ultraviolet-B (UV-B) radiation, Se supply, and their combination on growth and physiological traits of wheat (Triticum aestivum L., cv. Han NO.7086) seedlings were studied. The objective was to elucidate whether Se could alleviate the expected adverse effects of UV-B stress on seedlings. UV-B treatment caused a marked decline in growth parameters and total chlorophyll content and changed biomass allocation between aboveground and underground parts, which led to an increase in the root/shoot ratio. UV-B treatment also increased MDA content and the rate of superoxide radical (O₂^·−) production, although it increased some antioxidant (proline, phenolic compounds, and flavonoids) content and activity of antioxidant enzymes (peroxidase, superoxide dimutase, catalase (CAT)). Se treatment only increased total chlorophyll content and CAT activity. Compared with UV-B treatment alone, the combined treatment with UV-B and Se induced a significant increase in the biomass, total chlorophyll content, antioxidant content, and activity of antioxidant enzymes, and an evident decrease in MDA content and the rate of O₂^·− production. The results of this study demonstrated that Se alleviated the damage caused by UV-B to wheat seedlings to some extent by increasing antioxidant enzyme activity and antioxidant content.     

Composted sewage sludge can improve the physiological properties of<Emphasis Type="Italic">Betula schmidtii</Emphasis> grown in tailings

We investigated how the application of composted sewage sludge to tailings affects the physiological response of woody plants growing on abandoned coal-mining sites. Twenty seedlings ofBetula schmidtii were transplanted to pots containing various combinations of artificial soil plus nursery soil, tailings, composted soil, or tailings amended with composted soil. Dry weights, shoot to root ratios, relative growth rates (RGR), chlorophyll content and fluorescence, and carbohydrate concentrations were assessed at the end of the experiment. Growth responses differed significantly among soil types. For example, dry weights were greatest for seedlings grown in composted soil and smallest for plants raised in pure tailings. Shoot to root ratios were higher for seedlings in composted soil compared with those in either tailings or nursery soil. Leaf chlorophyll content was twice as high for seedlings from composted soil than for those in the nursery soil or tailings; chlorophyll fluorescence (Fv/Fm) was lower for seedlings in either nursery soil or tailings than for those in composted soil. In contrast, plants grown in either nursery soil or tailings had higher starch concentrations in their stems, whereas the carbohydrate allocation of seedlings in composted soil was highest in the leaves, followed by stems and roots. Overall, the carbohydrate content was highest in the leaves, except for seedlings treated with tailings. Therefore, we believe that composted soil can improve the physiological and biochemical properties of trees growing in tailings when appropriate nutrients are supplemented.     

茶多酚对盐胁迫下小麦幼苗叶片生理特性的影响

以春小麦"陇春30号"为实验材料,主要研究了150 mmol/L NaCl和不同浓度(25 mg/L和100 mg/L)茶多酚(tea polyphenols, TP)单独或复合处理对小麦幼苗叶片叶绿素含量、叶绿素荧光参数及过氧化氢(H₂O₂)产生等生理特性的影响。结果表明:(1)150 mmol/L NaCl单独处理导致小麦幼苗叶片叶绿素含量及光适应下实际光量子产量[actual light quantum yield,Y(II)]、光化学淬灭(photochemical quenching, qP)、光合电子传递效率(photosynthetic electron transfer efficiency, ETR)均降低,非光化学淬灭(non-photochemical quenching, NPQ)增大;TP单独处理不影响这些指标。(2)盐胁迫诱导细胞壁过氧化物酶(cell wall-peroxidase, cw-POD)、二胺氧化酶(diamine oxidase, DAO)和多胺氧化酶(polyamine oxidase, PAO)...     

Effect of Morpholine Systemic Fungicides on the Chloroplast Pigments of Wheat and Maize

Abstract

The growth, chlorophyll and carotenoid contents of wheat and maize seedlings as influenced by a soil drench of 250 μM of tridemorph or fenpropimorph, were studied. It was found that the length of the shoot, primary leaf, and root, as well as the leaf area were significantly reduced in the fungicide treated seedlings. Although the dry matter percentage was higher in the treated seedlings as compared to the control, the fresh or dry weight per shoot remained lower in the fungicide treated seedlings. The chloroplast pigments in the treated seedlings of both crops were unaffected, suggesting that the fungicides had no significant effect on the chlorophyll or carotenoid biosynthesis.     

Pb2+胁迫对两种小麦幼苗生理特性影响的研究

以两种小麦西旱2号和宁春4号幼苗为供试材料,研究了不同浓度Pb(NO₃)₂处理对其叶绿素含量、抗氧化酶活性及渗透性调节物等生理特性的影响。结果发现,两种小麦在低浓度铅处理下幼苗叶片叶绿素含量及超氧化物歧化酶（SOD）活性均无显著变化,而高浓度铅胁迫使其叶绿素a（Chla）、叶绿素b（Chlb）及叶绿素总量明显减少,但SOD活性显著升高,且相同浓度铅胁迫对小麦宁春4号幼苗叶片叶绿素的破坏作用明显强于对西旱2号的作用;不同浓度硝酸铅处理诱导两种小麦幼苗过氧化氢酶（CAT）、过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）活性升高,但不影响丙二醛（MDA）含量;此外,Pb²⁺处理使小麦幼苗叶片脯氨酸含量升高,此效应具有浓度依赖性,但铅处理不影响可溶性糖相对含量。结果表明,铅胁迫对两种小麦幼苗叶片叶绿素造成了破坏,却不同程度诱导抗氧化酶活性及脯氨酸含量升高,即表现出较强的抗氧化能力和渗透调节能力,增强了小麦对铅的耐受性,因而胁迫诱导两种小麦叶片MDA含量变化与对照比无显著性差异。     

混料设计优化黑木耳菌丝生长的农业剩余物配方

【背景】菌林矛盾日益突出,农业剩余物资源丰富,可作为食用菌栽培主要基质。【目的】筛选出适合黑木耳菌丝生长的农业剩余物配方。【方法】以大豆秸秆、油菜秸秆、玉米秸秆、花生秸秆、小麦秸秆和杂木屑等6种基质为原料,运用单纯形格子法进行配方设计,分析不同基质交互作用对黑木耳菌丝生长速率、菌丝生长指数、漆酶酶活、多酚氧化酶酶活和纤维素酶酶活的影响。【结果】在这些农业剩余物基质中,大豆秸秆基质最适合黑木耳菌丝生长,其次是油菜秸秆。3种主料共同作用可以优化出最适合黑木耳菌丝生长的基质配比。【结论】最终优化出一个适合黑木耳菌丝生长的农业剩余物配方：杂木屑49.4%、油菜秸秆16.4%、大豆秸秆12.2%、麦麸20%、蔗糖1%、CaSO₄ 1%。本研究为“以草代木”栽培黑木耳提供了理论基础。     

The effect of soil compaction on germination and early growth of Eucalyptus albens and an exotic annual grass

Most agricultural land has been compacted to some degree by heavy machinery or livestock trampling. This legacy is expected to influence the success of tree seedling recruits in farmland areas where natural regeneration is being encouraged. We investigated the impact of soil compaction on seedlings of a woodland eucalypt (Eucalyptus albens) and an annual grass competitor (Vulpia myuros) in a laboratory experiment. Replicate soil cores were created at five bulk density levels; 1.0, 1.1, 1.2, 1.3 or 1.4 Mg m^?3 with a soil water content of 20%. The depth of root penetration declined linearly with increasing bulk density, resulting in a decrease in root depth of around 75% in the most compacted soil compared with the least compacted soil for both species. Shoot length and primary root length did not vary between soil bulk density levels for either species, but seedlings responded to increasing levels of compaction with oblique (non‐vertical) root growth. Results suggest that young seedlings of both E. albens and V. myuros will be more susceptible to surface drying in compacted than uncompacted soils and therefore face a greater risk of desiccation during the critical months following germination. Any competitive advantage that V. myuros may have over E. albens is not evident in differential response to soil compaction.     

Effect of NaCl,water stress or both on gas exchange and growth of wheat

Responses of wheat (Triticum aestivum L.) to various concentrations of NaCl and levels of drought were followed. With the rise of NaCl or drought, or NaCl and drought together, growth was retarded. The water content of shoots and roots was mostly unchanged. The chlorophyll and carotenoid contents were increased in plants subjected to salinity or drought or both. Only high salinity level induced a considerable decrease in net photosynthetic rate (P_N) and dark respiration rate (R_D). P_N and R_D were decreased with the decrease of soil moisture content. The content of Na⁺ in the shoots and roots of wheat plants increased with increasing salinity or decreasing soil moisture content or both treatments. Considerable variations in the content of K⁺, Ca²⁺ or Mg²⁺ were induced by the NaCl, drought or both treatments.     

Soil transfers from valley oak (Quercus lobata Nee) stands increase ectomycorrhizal diversity and alter root and shoot growth on valley oak seedlings

 Soils from valley oak (Quercus lobata Nee) riparian areas of the Cosumnes River Nature Conservancy Preserve near Sacramento, California were added to growth medium of valley oak seedlings grown in a greenhouse or in agricultural fields at Cosumnes which probably once supported valley oak trees and are now replanted with native riparian vegetation or allowed to revegetate naturally. Agricultural field soil from the Cosumnes River Preserve was presumed to be low or lacking in ectomycorrhizal inoculum. The study was designed to (1) determine whether valley oak stand soil transfer could cause mycorrhizal infection on valley oak seedlings in an agricultural field and in a greenhouse, (2) describe ectomycorrhizal morphological types formed on valley oak seedlings, and (3) determine whether seedling growth is enhanced more by transfer of natural valley oak stand soil than agricultural field soil. In the field study, transfer of forest soil increased average ectomycorrhizal diversity (2.4 types) more than transfer of agricultural field soil (1.2 types). Valley oak seedlings were responsive to ectomycorrhizal infection in the field study. With increase in mycorrhizal infection there was an increase in shoot growth at the expense of root growth. In the greenhouse study, both percent mycorrhizal infection and mycorrhizal diversity were increased more by transfer of oak forest and woodland soils than agricultural field soil. Eight morphotypes occurred on seedlings in forest and woodland soils but only three morphotypes in agricultural soil. This result strongly suggests that the agricultural field also harbors ectomycorrhizal propagules but forest and woodland soils support a more abundant and diverse ectomycorrhizal flora. Accepted: 17 August 1997     

栓皮栎幼苗对土壤干旱胁迫的生理响应

以栓皮栎一年生盆栽苗为实验材料,采用称重控水的方法,设置不同土壤水分胁迫梯度,系统分析其幼苗在不同干旱胁迫条件下的生理生化响应特征,以探索栓皮栎耐旱特性.结果显示:(1)栓皮栎幼苗叶片中3种保护酶(SOD、POD、CAT)活性在对照(CK,土壤相对含水量19.5％～21.5％)条件下保持稳定,而中度干旱(T2,9.5％～11.5％)和重度干旱(T3,5.5％～7.5％)条件下,随着胁迫时间的延长呈先增高后降低的趋势,且变化的幅度在不同胁迫强度下存在差异.(2)在整个干旱胁迫过程中,各胁迫处理叶片丙二醛(MDA)含量均呈上升趋势,不同胁迫强度的变化幅度不同;叶片中的可溶性蛋白含量和根系活力随着干旱胁迫程度的增强呈先增高后降低的趋势.(3)栓皮栎幼苗叶片的脯氨酸含量随着干旱胁迫时间的延长表现出先增加后降低的趋势;叶片叶绿素a、叶绿素b、总叶绿素含量以及叶绿素a/b值均呈逐渐降低的趋势.研究表明,栓皮栎幼苗在短期和轻度干旱胁迫下通过提高自身的保护酶活性、增加可溶性蛋白和脯氨酸含量、提高根系活力等来抵御干旱环境的伤害,从而表现出较强的耐旱特性;而在重度干旱胁迫条件下,栓皮栎幼苗自我调节能力丧失,体内代谢紊乱,导致保护酶活性、可溶性蛋白、脯氨酸含量和根系活力等下降,从而受到干旱伤害.     

Mycorrhizal inoculant alleviates salt stress in<Emphasis Type="Italic"> Sesbania aegyptiaca</Emphasis> and<Emphasis Type="Italic"> Sesbania grandiflora</Emphasis> under field conditions: evidence for reduced sodium and improved magnesium uptake

A field experiment was conducted to examine the effect of the arbuscular mycorrhizal fungus Glomus macrocarpum and salinity on growth of Sesbania aegyptiaca and S. grandiflora. In the salt-stressed soil, mycorrhizal root colonisation and sporulation was significantly higher in AM-inoculated than in uninoculated plants. Mycorrhizal seedlings had significantly higher root and shoot dry biomass production than non-mycorrhizal seedlings grown in saline soil. The content of chlorophyll was greater in the leaves of mycorrhiza-inoculated as compared to uninoculated seedlings. The number of nodules was significantly higher in mycorrhizal than non-mycorrhizal plants. Mycorrhizal seedling tissue had significantly increased concentrations of P, N and Mg but lower Na concentration than non-mycorrhizal seedlings. Under salinity stress conditions both Sesbania sp. showed a high degree of dependence on mycorrhizae, increasing with the age of the plants. The reduction in Na uptake together with a concomitant increase in P, N and Mg absorption and high chlorophyll content in mycorrhizal plants may be important salt-alleviating mechanisms for plants growing in saline soil.     

The effect of calcium on the production of ethylene and abscisic acid by fungus Fusarium culmorum and by wheat seedlings infected with that pathogen

Wheat seedlings infected and non-infected with Fusarium culmorum were grown on mediums with different content of calcium (0, 2, 4, 8 mM). It was found that the higher the content of calcium in the medium, the greater the amounts of ethylene produced in both non-infected and infected wheat seedlings, whereas the level of ABA in their tissues was decreased. Taking into consideration the fact that ethylene inhibits, whereas ABA stimulates the growth and development of Fusarium culmorum, it may be assumed that the production of ethylene increased under the influence of calcium and the decreased level of ABA in wheat seedlings causes the reduction growth and development of pathogen and as a result it lowers the degree of infection of wheat seedlings by this fungus. Thus, on the base of the obtained results it may be concluded that the inhibiting influence of calcium on injurying the wheat seedlings by Fusarium culmorum may be caused by the influence of this cation on the hormone balance in the plant.