Effect of seaweed concentrate on yield of nutrient-stressed tepary bean (Phaseolus acutifolius gray)

The effect of the seaweed concentrate Kelpak on the yield of the tepary bean (Phaseolus acutifolius L.) grown under conditions of varying nutrient supply was investigated. Kelpak significantly increased the yield of plants growing at all concentrations of nutrient supply by increasing bean weight rather than bean number. Kelpak also tended to increase the N concentration of the beans. The results suggest that Kelpak did not act simply as a fertilizer, but as some kind of biostimulant.     

Effect of seaweed concentrate on the growth and mineral nutrition of nutrient-stressed lettuce

The effects of the seaweed concentrate Kelpak on the growth and mineral nutrition of lettuce plants grown under conditions of varying nutrient supply were investigated. Kelpak significantly increased the yield and the concentration and amounts of Ca, K and Mg in the leaves of lettuce receiving an adequate supply of nutrients, but had little effect on nutrient stressed plants. Results are discussed in relation to the physiological mechanisms that have been proposed to explain the beneficial effects of seaweed concentrate on plants.author for correspondence     

Effect of seaweed concentrate on growth and development of the marigoldTagetes patula

The seaweed concentrate Kelpak, made fromEcklonia maxima, and applied as a foliar spray or a root drench at transplanting, improved both the vegetative and reproductive growth of marigolds. Of particular significance is that the overall production of seeds (fruits) was increased by as much as 50% in some instances. Very low concentrations of seaweed concentrate were not always effective, while the higher dosages decreased vegetative growth.     

Evidence for the presence of plant growth regulators in commercial seaweed products

Although seaweeds and various seaweed products have been utilized in agricultural practices for many years, the precise mechanism by which they elicit their beneficial growth responses is still not fully understood. The amount of mineral nutrients in commercial preparations cannot account for the magnitude of the responses. Some other factor, such as the presence of endogenous plant growth regulators is, therefore, thought to be involved. This paper reviews the literature supporting evidence for the occurrence of plant hormones in commercial seaweed preparations.abbreviations SWC seaweed concentrate - PGR plant growth regulator - GC-MS gas chromatography/mass spectrometry - ¹H-NMR proton nuclear magnetic resonance - HPLC high performance liquid chromatography     

Effect of seaweed concentrate on hydroponically grown spring barley

Spring barley (Hordeum vulgare cv. Triumph) was grown hydroponically over a 6-week period. Two treatments were incorporated either into the hydroponic solution or sprayed onto the plants at rates of 1 ml per 3 litres. The treatments applied were: (i) a seaweed concentrate prepared fromAscophyllum nodosum (L.) Le Jolis (marketed as Maxicrop Triple), (ii) a ‘Trace element’ treatment incorporating the micro and macro nutrients added to the seaweed extract base to produce the formulated product Maxicrop Triple and (iii) a control treatment. Irrespective of the mode of application, plants treated with Maxicrop Triple grew faster than plants under either of the two other treatments. Elevated growth rates were also found for the ‘Trace element’ treated plants when incorporated into the hydroponic solution. At the final harvest, plants with Maxicrop Triple incorporated into the hydroponic solution showed increases from 56–63% over the control treatment for the growth characteristics measured. ‘Trace element’-treated plants produced increases of between 25–45%. When the treatments were sprayed the effect was less pronounced. Maxicrop Triple increased growth characters by 35–38% and the ‘trace element’ treatment gave increases in the range of 2–13%.     

Effect of seaweed concentrate fromEcklonia maxima (Osbeck) Papenfuss onMeloidogyne incognita infestation on tomato

Seaweed concentrate (SWC), prepared fromEcklonia maxima, when applied as a soil drench to tomato seedlings, significantly increased plant growth and reduced infestation byMeloidogyne incognita. Foliar applied SWC had little effect on plant growth and increased nematode galling. Ashing SWC reduced the suppressive effect on nematode infestation. In anin vitro experiment, SWC lessened infestation of root-knot nematodes on excised roots of a susceptible cultivar of tomato. Application of the same concentrations of SWC to a nematode-resistant cultivar increased the number of egg masses.     

The effect of thidiazuron on the yield of wheat grown with varying nutrient supply

The effect of the synthetic cytokinin thidiazuron on the yield of wheat growing under conditions of varying nutrient supply was investigated. Applications of thidiazuron during the early growth stages of wheat promoted tillering but reduced yield. Applications of thidiazuron during flag leaf senescence had little effect on yield. However, the yield of plants was increased at all levels of nutrient supply by treating plants with paclobutrazol during the early growth stages followed by thidiazuron during flag leaf senescence. Yield increases were greatest in moderately nutrient stressed plants, but were accompanied by a reduction in the N concentration of the grain. Possible reasons for the interaction between thidiazuron and paclobutrazol in increasing the yield of wheat are discussed.     

Fast changes in growth rate and cytokinin content of the shoot following rapid cooling of roots of wheat seedling

Changes in the concentration of cytokinins were studied following root cooling. Simultaneously, the growth rate of the second leaf was monitored with a highly sensitive growth sensor attached to its tip. Cytokinins were separated by thin layer chromatography and immunoassayed using antibodies to zeatin riboside. The extension rate of the second leaf decreased within 15 minutes of cooling the nutrient medium from 24 °C to 4 °C. The concentration of cytokinins in shoots decreased with similar rapidity. In contrast cytokinins in roots increased slightly during the initial period of cooling before declining. The sharp decrease in cytokinin concentrations in shoots 15 minutes after cooling of roots may contribute to the abrupt inhibition of shoot growth.     

播期对春小麦生长发育及产量的影响

为了给陇中半干旱区春小麦高产栽培提供依据,2010年在甘肃定西进行了春小麦分期播种试验,并对不同播期条件下春小麦生长发育及产量形成进行了分析。结果表明:随着播期的推迟,春小麦播种-抽穗期日数减少、全生育期明显缩短;5月下旬之前,越早播种的春小麦LAI越大,5月下旬之后,播种愈晚春小麦LAI越大。早播春小麦LAI峰值靠前,晚播峰值滞后;6月下旬之前,播期早的春小麦叶绿素含量高于播期晚的,6月下旬之后播期愈早叶绿素含量下降愈快;不同播期春小麦群体生长率和净同化率在孕穗-抽穗期后差异显著,表现为3月18日播期最大,4月7日播期最小。各播期干物质累积在拔节期后表现为快速递增趋势。在拔节期前,早播处理的干物质积累速率较慢。随着播期的推迟,单株干物质最大积累速率出现时间提前,籽粒最大灌浆速率出现时间推迟,千粒重表现为先升后降;灌浆3个阶段各参数受播期影响比较显著;早播春小麦产量最高。     

Isolation and identification of cytokinins in a new commercial seaweed product made from Fucus serratus L.

Marine Adenine Cytokinins (MAC) is a new commercial seaweed product made from Fucus serratus L. Cytokinins were isolated from this extract by cation exchange, paper and high performance liquid chromatography. Cytokinins were detected and isolated by bioassay guided fractionation using the soybean callus assay. Trans-zeatin, dihydrozeatin and iso-pentenyladenosine were identified by GC-MS as being the dominant cytokinins present in MAC. This revised version was published online in August 2006 with corrections to the Cover Date.     

Changes in cytokinin and auxin concentrations in seaweed concentrates when stored at an elevated temperature

Two seaweed concentrates were made from the kelps Ecklonia maxima and Macrocystis pyrifera using a cell burst method. Cytokinin- and auxin-like activities were measured using the soybean callus and mungbean bioassays, respectively. Cytokinin-like activity was detected in both seaweed concentrates, being equivalent to approximately 50 μg L⁻¹ kinetin. Auxin-like activity was also detected in both concentrates with the E. maxima derived concentrate having higher biological activity, equivalent to 10⁻⁵–10⁻⁴ M indole-butyric acid. Two replicates of each concentrate were stored at 54 °C for 14 days to accelerate the effects of storage. Both fresh and stored samples of the two seaweed concentrates were analysed for their endogenous cytokinin and auxin content. The samples were purified using a combined DEAE-Sephadex octadecylsilica column and immunoaffinity chromatography based on wide-range cytokinin and IAA specific monoclonal antibodies. These extracts were analysed by HPLC linked to a Micromass single quadrupole mass spectrophotometer. Eighteen and nineteen different cytokinins were detected, respectively, in the two concentrates, with trans-zeatin-O-glucoside being the main cytokinin present. Accelerated storage of the concentrates caused an increase in the total cytokinin concentration with a large increase in the aromatic meta-topolin. Indole-3-acetic acid was the main auxin in both seaweed concentrates. Indole conjugates, including amino acid conjugates, were also quantified. The total auxin concentration decreased with accelerated storage for both concentrates. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effect of fulvic acid on the dose effect of selenite on the growth of wheat

The effect of fulvic acid on the dose effect of selenite has been studied by using the hydroponics culture of wheat in the presence of selenite and fulvic acid (FA). The bioavailability of Se was investigated by 5 morphological end points and 12 biological and biochemical end points at different phases of growth of wheat seedling and seed germination. The “platform” of the dose effect observed indicates that the presence of FA can have both the beneficial effects and antagonists on the toxicity of Se to a certain extent.     

The effect of fertilizer application on farming of the seaweed Undaria pinnatifida (Laminariales, Phaeophyta)

A slow-release ammonium phosphate fertilizer coated with porous plastic was tested on Undaria pinnatifida (Harvey) Suringar as a possible solution to the nutrient deficiency in seawater that causes quality and yield deterioration in seaweed farming. The yield of U. pinnatifida within the fertilized area was 17–40% greater than that of the control area (unfertilized area). In addition, two harvests were possible per season and the quality of harvested U. pinnatifida was also better than that outside the fertilizer diffusion area. The released NH₄-N did not increase the concentration of NH₄-N outside the farming area. Therefore, this fertilizer increased yield and improved quality without causing water pollution.     

Screening plant growth-promoting rhizobacteria for improving growth and yield of wheat

AIMS: Plant growth promoting rhizobacteria (PGPR) are commonly used as inoculants for improving the growth and yield of agricultural crops, however screening for the selection of effective PGPR strains is very critical. This study focuses on the screening of effective PGPR strains on the basis of their potential for in vitro auxin production and plant growth promoting activity under gnotobiotic conditions. METHODS AND RESULTS: A large number of bacteria were isolated from the rhizosphere soil of wheat plants grown at different sites. Thirty isolates showing prolific growth on agar medium were selected and evaluated for their potential to produce auxins in vitro. Colorimetric analysis showed variable amount of auxins (ranging from 1.1 to 12.1 mg l-1) produced by the rhizobacteria in vitro and amendment of the culture media with l-tryptophan (l-TRP), further stimulated auxin biosynthesis (ranging from 1.8 to 24.8 mg l-1). HPLC analysis confirmed the presence of indole acetic acid (IAA) and indole acetamide (IAM) as the major auxins in the culture filtrates of these rhizobacteria. A series of laboratory experiments conducted on two cv. of wheat under gnotobiotic (axenic) conditions demonstrated increases in root elongation (up to 17.3%), root dry weight (up to 13.5%), shoot elongation (up to 37.7%) and shoot dry weight (up to 36.3%) of inoculated wheat seedlings. Linear positive correlation (r = 0.99) between in vitro auxin production and increase in growth parameters of inoculated seeds was found. Based upon auxin biosynthesis and growth-promoting activity, four isolates were selected and designated as plant growth-promoting rhizobacteria (PGPR). Auxin biosynthesis in sterilized vs nonsterilized soil inoculated with selected PGPR was also monitored that revealed superiority of the selected PGPR over indigenous microflora. Peat-based seed inoculation with selected PGPR isolates exhibited stimulatory effects on grain yields of tested wheat cv. in pot (up to 14.7% increase over control) and field experiments (up to 27.5% increase over control); however, the response varied with cv. and PGPR strains. CONCLUSIONS: It was concluded that the strain, which produced the highest amount of auxins in nonsterilized soil, also caused maximum increase in growth and yield of both the wheat cv. SIGNIFICANCE AND IMPACT OF STUDY: This study suggested that potential for auxin biosynthesis by rhizobacteria could be used as a tool for the screening of effective PGPR strains.     

苗期刈割伤害对春小麦生长及产量的影响

通过1996年大田试验研究了黄土高原半干旱区春小麦苗期（三叶－心期）受到不同强度刈割伤害（模拟动物的采食）后的补偿作用,结果,在大田试验条件下,受轻度刈割（刈割一半叶面积,H0,H1）,春小麦的补偿效应大于受重度刈割（刈割全部叶面积T0,T1）春小麦的补偿效应,且都低于未受刈割处理（对照,CK0,CK1）,即CK0＞H0＞T0;CK1＞H1＞T1,刈割处理后,灌溉一次水（CK1,H1,T1）虽可增强其补偿能力,促进小麦的生长,但仍为低补偿。     

Modification of foliar solute concentrations by calcium in two species of wheat stressed with sodium chloride and/or potassium chloride

The effects of saline-stresses due to different salts on growth and on foliar solute concentrations in seedlings of two species of wheat that differed in salt tolerance. Triticum aestivum L. cv. Probred and Triticum turgidum L. (Durum group) cv. Aldura, were studied. Triticum aestivum is the more salt tolerant species. The salts used were NaCl, KCI, a 1:1 mixture of NaCI and KCI, and these same monovalent cation salts but mixed with CaCI₂ at a ratio of 2:1 on a molar basis of monovalent to divalent cation salts. Growth inhibition of both species was a function of media osmotic potentials. There was a small additional inhibition of growth if KCI replaced NaCI as the salinizing salt. CaCI₂ had little or no effect on growth inhibition beyond an osmotic effect except at the most severe stress level, i.e. when Ca²⁺ concentrations may be excessive. The amounts of water-soluble Ca²⁺ were about 10 times higher in leaves of plants grown in the presence of CaCI₂ than in its absence, but its concentrations even then were approximately 10% or less of those of the monovalent cations. Including CaCI₂ in growth media resulted in a reduction in the amount of Na⁺ in leaves compared to the amounts in plants grown at the same osmotic potential but in the absence of CaCI₂. Triticum aestivum was a better Na⁺-excluder than T. turgidum. With CaCI₂ in media, (Na⁺+ K⁺) remained relatively constant or increased by small amounts as media osmotic potentials décreased. In the absence of CaCI₂₊ (Na⁺+ K⁺) increased by large amounts when media osmotic potentials were at ?0.6 and ?0.8 MPa. It is concluded that the accumulation system in leaves for monovalent cations was under feed-back control, and that this control mechanism was inhibited by high media concentrations of Na⁺ and/or K⁺. Sucrose was present at a constant amount under all growth conditions. Proline started accumulating when (Na⁺+ K⁺) exceeded a threshold value of 200 μmol (g fresh weight)^?1. Its concentration was 5 to 13% of that portion of (Na⁺+ K⁺) that exceeded the threshold value.     

Interaction of salinity and enhanced ammonium and potassium nutrition in wheat

Wheat (Triticum aestivum L.) was grown to maturity in a pot experiment in a calcareous silty sand soil. N was applied at two levels as granulated N-P fertilizers, amended or not with nitrification inhibitors (1% and 5% DCD, 1% N-serve). Potassium as KCl was given at three levels of application. P was applied at a uniform rate. Two levels of salinity were obtained by using the soil as such (EC= 0.3 mmho/cm) and by adding NaCl to the same soil (EC=2.4 mmho/cm). 1% DCD and 1% N-serve treatments gave significantly higher wheat grain yields and N-uptake than the other ones. Nitrate content of leachates indicated a prevalent nitrate nutrition in the treatment without nitrification inhibitors. The 5% DCD treatment showed a yield depression. In the lower N level treatments, a significant yield increase, generated by 1% DCD and N-serve was found in the salinized soil as compared to the non-saline soil. Soil salinity reduced N-uptake when nitrification inhibitors were not present. In treatments having the inhibitors, N-uptake was equal or greater in the salinized than in the non saline soil. An enhanced ammonium nutrition increased the P uptake.     

Modelling potassium uptake by wheat (Triticum aestivum) crops

Spring wheat was grown in the field under deficient and sufficient levels of soil K and with high and low supplies of fertiliser nitrogen. Measurements were made of K uptake, soil nutrient supply parameters, root growth and, in solution culture, root influx parameters. Mechanistic models predicted uptake reasonably well under K-deficient conditions, but over-predicted uptake, by as much as 4 times, under K-sufficient conditions. The over-prediction was apparently due to poor characterisation of plant demand.     

The effect of soil strength on the yield of wheat

Although it is well-known that high soil strength is a constraint to root and shoot growth, it is not clear to what extent soil strength is the main physical stress that limits crop growth and yield. This is partly because it is difficult to separate the effects of soil drying and high soil strength, which tend to occur together. The aim of this paper is to test the hypothesis that for two different soil types, yield is closely related to soil strength irrespective of difference in soil water status and soil structure. Winter (Triticum aestivum L., cv. Hereward) and spring wheat (cv. Paragon) were grown in the field on two soils, which had very different physical characteristics. One was loamy sand and the other sandy clay loam; compaction and loosening treatments were applied in a fully factorial design to both. Crop growth and yield, carbon isotope discrimination, soil strength, water status, soil structure and hydraulic properties were measured. The results showed that irrespective of differences in soil type, structure and water status, soil strength gave a good prediction of crop yield. Comparison with previous data led to the conclusion that, irrespective of whether it was due to drying or compaction (poor soil management), soil strength appeared to be an important stress that limits crop productivity.