Effects of defoliation at different growth stages and in different grain-filling environments on the growth and yield of spring barley

The yield of spring barley grown outside was little affected by the removal of all fully expanded leaves during late tillering or early stem extension but was decreased by defoliation either earlier or later. Removal of all except the top two leaves when 50% of the ears were fully emerged also had relatively little effect on yield but damage was increased if only the flag leaf was retained, especially if the leaves apart from the flag leaf were removed 10 days earlier when the first awns were visible. Defoliation treatments, including those which had little effect on barley grown outside, generally had proportionately greater effects if the plants were moved to a warm glasshouse at the start of grain filling.     

Effects of a short-term p-hydroxybenzoic acid application on grain yield and yield components in different tiller categories of spring barley

The aim of these experiments was to evaluate how thresholds for phytotoxic substances obtained in seedling bioassays relate to yield losses or changes in yield components of mature barley crops after a short-term exposure to p-hydroxybenzoic acid. Under laboratory conditions a treatment with 1.81 mM p-hydroxybenzoic acid significantly reduced the radicle length of barley, whereas coleoptile elongation was less sensitive. The inhibition of the radicle length and coleoptile elongation was greater if the pH of the test solution was not buffered at pH 5.5. In a glasshouse trial the effect of p-hydroxybenzoic acid on the radicle and coleoptile elongation of spring barley was compared with the yield response after a three day exposure either during germination or at the double ridge stage of apex development. Applications of 0.72 mM, 1.44 mM and 3.62 mM p-hydroxybenzoic acid averaged over the treatments during germination or at the double ridge stage of development caused a yield reduction in the single ear weight of 5%, 13% and 19% in comparison with the control, respectively. The higher tiller categories in general showed a greater sensitivity towards an application of p-hydroxybenzoic acid and, therefore, could not compensate for the yield decrease of the main stem tiller. A single application of p-hydroxybenzoic acid either at germination or at the double ridge stage may cause yield losses, as reported from no-till systems or cereal monocultures. The data have implications for the interpretation of seedlings bioassays in allelopathic research and their applicability in estimating yield losses caused by phytotoxic substances. ei]Section editor: R Merckx     

Effects of fungicide treatments and variety on development, grain growth and yield of spring barley

The effects of four fungicide treatments for the control of mildew on spring barley were assessed in three field experiments, one in each of the years 1981, 1982, 1983. The fungicide treatments (+/ - triadimenol seed treatment and +/ - triadimefon foliar spray applied during early booting) were chosen to control mildew, and hence affect yield determining processes, at different times in the life of the crop. Two of the experiments also tested different nitrogen amounts and the third tested four varieties differing in their degree of mildew resistance. Mildew appeared too late to affect the production and survival of spikelets and shoots, but reduced average grain weight by reducing the rate of grain growth. Grains in the upper part of the ear had a considerably lower growth rate and final weight than grains in central and basal positions but there was no evidence that the effects of mildew on grain size depended upon grain position within the ear. Mildew incidence increased with increasing nitrogen and varietal susceptibility but there were few significant interactions between these factors and fungicide treatment for grain yield. The degree of mildew control achieved by the seed treatment varied with barley variety. Use of the two successive fungicide treatments did not yield more barley than use of either alone. Amongst varieties, grain positions within the ear and fungicide treatments there was a close correlation between rate of grain growth and final grain weight. Duration of grain growth was not related to rate of grain growth or final grain weight but was inversely correlated with mean temperature during the period of rapid grain growth. The temperature sums during the period of rapid grain growth were similar for the three years and it is suggested that a more precise knowledge of the relationships between mildew incidence, varietal susceptibility and rate of grain growth may enable more accurate predictions to be made about likely yield responses to fungicide treatments.     

Genotypic variation in silicon concentration of barley grain

Soluble silicon (Si) in foods and drinks has been suggested to have a protective effect against neurotoxicity of Al. We investigated the genotypic variation in Si concentration of barley grain, which has many uses including in livestock feeds, malts for beer and whisky, and some foods for human consumption. Two collections of barley, grown in the same field, were subjected to analysis; 274 standard varieties selected at the Barley Germplasm Center of the Research Institute for Bioresources, Okayama University (SV), and 135 varieties from the Barley Core Collection of Americans (BCCAM). The Si concentration of barley grain showed large variation, ranging from 0 (under detection) to 3600 mg kg^–1 in SV and from 0 to 3800 mg kg^–1 in BCCAM barleys. The Si concentration was much lower in hull-less barley than in hulled barley. The Si concentration of two-row barley was similar to that of six-row barley, suggesting that Si concentration is not affected by the number of spike rows. Si concentration also did not differ with the origin of the barley variety. More than 80% of total Si was localized in the hull. The Si concentration of the hull was between 15343 and 27089 mg kg^–1 in the varieties tested. A close correlation was obtained between the Si concentrations of barley grains harvested in different years, suggesting that the variation in Si concentration of barley grain is controlled genetically. These results provide fundamental data for breeding Si-rich cultivars.     

Fractions of barley spent grain as media for growth of probiotic bacteria

The application of the protein and polysaccharide fractions of barley spent grain as a basis of growth media for probiotic bacteria was studied. High values of biomass yield, cell viability, and organic acid production were observed in the variants of media containing the barley spent grain supplemented with lactose, ascorbic acid, yeast extract, and mineral salts. Cells of lactic acid bacteria and bifidobacteria had the typical rod-shaped morphology.     

Differential levels of mite infestation of wheat and barley in Czech grain stores

Abstract  While mites are able to utilize numerous food sources, the suitability of the food strongly influences population growth. The different suitabilities of various stored agricultural products will thus affect the level of infestation. In this study, we compared field mite infestation rates in two stored cereals: wheat and barley. We analyzed mite abundance, frequency and species composition in samples of grain obtained from 79 selected Czech grain stores. Stored barley seemed to be more vulnerable to mite attack than wheat, as we consistently found more infested samples, more species and higher mean and median mite abundance per sample in barley as compared to wheat. The mean mite abundance per sample were 55 and 506 individuals for wheat and barley, respectively. In barley, 10% of samples exceeded allergen risk threshold (i.e., 1 000 individuals per kg of grain). Altogether, 25 species were identified from approximately 35 000 individuals. The most frequently identified species were the same in wheat and barley, that is, Tydeus interruptus Sig Thor, Acarus siro L., Tarsonemus granarius Lindquist, Lepidoglyphus destructor (Schrank) and Tyrophagus putrescentiae (Schrank). Based on principal components analysis, we found a closer association of T. interruptus , T. putrescentiae , L. destructor and Cheyletus eruditus (Schrank) with barley samples, corresponding to the high frequency and abundance values of these mites. The probable reasons for the higher infestation, especially mite abundance in barley, are discussed in relation to the higher proportion of crushed parts, which may release favorable nutrient sources and amplify the abundance values.     

Effect of fungicides on mycorrhizal colonization and growth of onion

Summary Effect of five fungicidesviz Agrosan. Benlate, Captan, Ceresan and Plantavax on VA mycorrhizal symbiosis in onion was studied in a phosphorus deficient, sandy loam soil. Two levels of fungicides (2.5 g and 25 g/g soil) were applied to the soil. Agrosan, Benlate and Plantavax applied at 25 g/g soil reduced the mycorrhizal colonization significantly. All the fungicides, except Captan, applied at lower concentration reduced plant growth and P uptake. Captan applied at the lower concentration had no effect on mycorrhizal colonization, plant growth and P uptake, and when applied at higher concentration had least effect on plant growth compared to other fungicides.Contribution of U.A.S. Research project DR/AMB-1.     

Aspergillus flavus colonization and aflatoxin B1 formation in barley grain during interaction with other fungi

Colonization of barley grain by Aspergillus flavus and formation of aflatoxin B₁ in the presence of Penicillium verrucosum, Fusarium sporotrichioides, and Hyphopichia burtonii were studied over a three-week period in all combinations of 20 or 30 °C and 0.97, 0.95 or 0.90 a_w. Grain colonization was assessed initially by observing hyphal extension on the grain surface, using scanning electron microscopy, and then from the proportion of seeds infected and numbers of colony forming units (cfu) formed. Aflatoxin b¹ concentrations were determined by enzyme linked immunosorbent assay using a monoclonal antibody. These studies showed that interaction between A. flavus and other fungi in paired culture had different effects on both colonization and aflatoxin formation depending on the species involved and environmental conditions. Germination of A. flavus spores was unaffected by the presence of other species on the grain surface. Subsequently, three principal patterns of A. flavus colonization of barley grain were observed through the incubation period in the presence of other fungal species: (a) colonization unaffected by the presence of other species; (b) colonization initially slower in the presence of other species but later differing little from pure cultures; and (c) colonization adversely affected by the presence of other species. Five main patterns of aflatoxin B₁ production were observed relative to pure culture but with no consistent relationship with species, a_w, temperature or incubation period; (a) little changed; (b) increased slowly; (c) decreased; (d) enhanced; and (e, f) increased initially but later decreased to (e) the same level as in pure culture or (f) to less than in pure culture. Generally, production of aflatoxin B₁ by A. flavus was less than in pure culture but sometimes was changed only slightly by the presence of P. verrucosum, F. sporotrichioides or H. burtonii or was temporarily enhanced.     

Effect of glutathione on dormancy breakage in barley seeds

A striking relation has been shown between the increase of glutathione levels during dormancy breakage of barley seeds and the induction of germination by exogenous glutathione. These findings suggested that glutathione may play a crucial role in dormancy breakage.     

Abscisic acid in developing grains of wheat and barley genotypes differing in grain weight

Two genetically related wheat lines growing in cabinets were given different temperatures during grain filling, and abscisic acid (ABA) was measured in whole grains by gas chromatography with an electron-capture detector. Three genetically related barley lines grown in the field were assayed for ABA content in endosperm and embryo fractions separately by radiommunoassay.Maximum grain growth rate and final weight per grain of the two wheat lines differed by 50–60% at low temperature and 30–40% at high temperature. During grain development two peaks in ABA level were observed at low temperature but only one at high temperature. At times when differences in grain growth rate between genotypes and between temperature treatments were large, the corresponding differences in ABA concentration were small. In barley, one line (Iabo 14) had 30% heavier grains than the other two (Onice and Opale). Endosperm ABA concentrations showed no clear differences between genotypes until grain filling was nearly complete. Embryo ABA levels were up to 10-times greater than those in the endosperm, with Opale having significantly less ABA in the embryo than the other two cultivars.Our experiments did not provide evidence for a causal relationship between ABA levels during grain filling and grain growth rate or final weight.Abbreviations ABA Abscisic acid - DAA days after anthesis - DW dry weight - FW fresh weight     

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%.     

Effects of foliar applied benzyladenine on grain yield and grain protein in wheat (Triticum aestivum L.)

The effects of foliar applications of nitrogen and benzyladenine (BA) on grain yield and grain protein of wheat grown under field conditions were studied over 2 years with 5 cultivars at 2 locations. Nitrogen (N) at 20 kg.ha^–1, and BA at 100 or 800 mg.l^–1 were applied alone or combined at pre and post-anthesis; applications of BA at 8 mg.l^–1 were also made on individual ears in order to study the effect on cell number. Weekly determinations of the chlorophyll content of the flag leaf were conducted after anthesis to study leaf senescence. At harvest, yield, yield components and grain protein percentage were determined. N and BA applications delayed chlorophyll loss in the flag leaf, but modified neither yield nor yield components. Foliarly applied BA increased grain protein in four of the five cultivars tested. It is concluded that delay of the senescence induced by BA might allow more energy to be available for N uptake by the crop leading to an increase in grain protein.Research supported by a CAFPTA grant 1656/86 and by CONICET, PID 30017700/85.CONICETComisión de Investigaciones Cientificas de la Provincia de Buenos AiresInstituto de Fisiologia Vegetal     

Effects of powdery mildew on grain filling in spring barley in contrasting environments

Circumstantial evidence from field experiments at Rothamsted suggested that effects of powdery mildew on grain filling in spring barley may be determined partly by temperature during the grain-filling period. An experiment was, therefore, done which compared the effects of fungicides applied to control powdery mildew on grain filling in early- and late-sown spring barley plants kept either out-of-doors throughout their growth (‘cool’ environment) or under the same conditions until the start of grain filling and then transferred to a heated glasshouse (‘warm’ environment) until harvested. Fungicides that controlled mildew increased the total grain yield of the late-sown barley more than that of the early-sown and much more in the warm environment than in the cool. On average, the effect of the fungicides in the cool environment was to increase grain yield by 17·7%. Small increases in numbers of grains/ear (+ 3·4%) and thousand-grain weight (TGW) (+ 2·3%) contributed to this increase but it could be attributed principally to an average increase in numbers of ears/plant of 12·4%. Contrastingly, fungicides increased average grain yield in the warm environment by 58·2%. Effects of the fungicides on numbers of ears/plant (+ 27·8%) and on numbers of grains/ear (+ 4·5%) were not significantly different to those in the cool environment, and the much greater responses in the warm than in the cool environment could be attributed mostly to much larger effects on grain size (+ 19·2%) The greater benefits of the fungicides and, by implication, the greater damage done by powdery mildew in the warm than in the cool environment cannot, unequivocally, be attributed to differences in temperature during grain-filling because the two environments clearly differed in other ways and especially in light intensity. Nevertheless, the results obtained do illustrate the potential risks involved in using data obtained under one set of circumstances to predict what will happen in another, especially when environments differ as greatly as glasshouses and fields.     

Interactions between fungicide, plant growth regulator, nitrogen fertiliser applications, foliar disease and yield of winter barley

Leaf size and foliar disease in winter barley increased with increasing total amounts of nitrogen applied to the crop: flag leaf areas increased at an average of 10% per 35 kg N ha^-1 Nitrogen top dressing applied in mid-March (G.S. 31) resulted in larger leaves, more foliar disease, more straw, delayed ear emergence, fewer grains ear^-1 and less grain yield than nitrogen applied in mid-April (G.S. 31). Application of chlormequat at G.S. 30 gave a variable response, but overall it increased fertile stems m-² and crop yield and decreased crop height but had no significant effect on straw yield. Fungicide treatments suppressed foliar disease and improved yield. Yield responses were greater when plant growth regulator and mid-March nitrogen had been applied at sites where more disease prevailed than with April-applied nitrogen. In one of the field experiments, on cv. Sonja, delaying the main nitrogen application until April, without fungicide treatment, gave a similar yield to that provided by nitrogen in March with two or three fungicide sprays.     

Field studies on the regulation of abscisic acid content and germinability during grain development of barley: molecular and chemical analysis of pre-harvest sprouting

To investigate whether the regulation of abscisic acid (ABA) content was related to germinability during grain development, two cDNAs for 9-cis-epoxycarotenoid dioxygenase (HvNCED1 and HvNCED2) and one cDNA for ABA 8'-hydroxylase (HvCYP707A1), which are enzymes thought to catalyse key regulatory steps in ABA biosynthesis and catabolism, respectively, were cloned from barley (Hordeum vulgare L.). Expression and ABA-quantification analysis in embryo revealed that HvNCED2 is responsible for a significant increase in ABA levels during the early to middle stages of grain development, and HvCYP707A1 is responsible for a rapid decrease in ABA level thereafter. The change in the embryonic ABA content of imbibing grains following dormancy release is likely to reflect changes in the expression patterns of HvNCEDs and HvCYP707A1. A major change between dormant and after-ripened grains occurred in HvCYP707A1; the increased expression of HvCYP707A1 in response to imbibition, followed by a rapid ABA decrease and a high germination percentage, was observed in the after-ripened grains, but not in the dormant grains. Under field conditions, HvNCED2 showed the same expression level and pattern during grain development in 2002, 2003, and 2004, indicating that HvNCED2 expression is regulated in a growth-dependent manner in the grains. By contrast, HvNCED1 and HvCYP707A1 showed a different expression pattern in each year, indicating that the expression of these genes is affected by environmental conditions during grain development. The varied expression levels of these genes during grain development and imbibition, which would have effects on the activity of ABA biosynthesis and catabolism, might be reflected, in part, in the germinability in field-grown barley.     

Commercially available plant growth regulators and promoters modify bulk tissue abscisic acid concentrations in spring barley, but not root growth and yield response to drought

Field and lysimeter experiments were conducted in 2002 to investigate the effects of an antigibberellin growth regulator (Moddus, active ingredient trinexapac‐ethyl, Syngenta Crop Protection UK Ltd, Whittlesford, Cambridge, UK) and an auxin‐stimulating (Route, active ingredient zinc ammonium acetate, De Sangosse Ltd, Swaffham Bulbeck, Cambridge, UK) growth promoter on root growth, soil water extraction and the drought response of spring barley. The effects on root growth and distribution were investigated in the field. The effects on the drought response were studied in 1.2‐m‐deep lysimeters packed with a loamy sand subsoil and sandy loam topsoil. Lysimeters were located under a fixed rain shelter, and drought was imposed by withholding irrigation. In both field and lysimeter experiments, growth regulator/promoters were applied to cv. Optic at early tillering according to the manufacturers’ recommendations. After withholding irrigation from lysimeters at Zadoks growth stage (GS) 21 (37 days after sowing), 50% of the profile available water had been depleted by flag leaf emergence (GS 37/39; 62 days after sowing). Drought significantly reduced stem biomass at ear emergence (GS 59; 78 days after sowing) but not leaf or ear dry weight; this was before there was any significant reduction in leaf water potential or stomatal conductance to water vapour. The reduction in stem biomass may reflect a change in partitioning between shoot and root in response to soil drying. When averaged over growth regulator/promoter treatments, drought reduced grain yield by approximately 1 t ha^?1. This was associated with a reduction in both ears per m² and grains per ear. The mean grain weight was not reduced by drought, in spite of significant reductions in stomatal conductance and canopy lifespan post‐anthesis. Route, and to a lesser extent Moddus, significantly increased abscisic acid accumulation in the stem base of droughted plants, and there was some indication of a possible delay in stomatal closure in Route‐treated plants as the soil moisture deficit developed. However, there was no significant effect on the amount of soil water extracted or grain yield under drought. Similarly, in field experiments, neither Route nor Moddus significantly altered total root length, biomass or distribution. There is little evidence from these experiments or in the literature to support the use of antigibberellin or auxin‐simulating growth regulator/promoters to modify root growth and drought avoidance of spring barley.     

Effects of net blotch on growth and yield of spring barley

The effect of net blotch on the growth and yield of cv. Beatrice spring barley was examined in a greenhouse experiment. Separate inoculations at growth stages 21 and 34 reduced green leaf area, root weight, leaf sheath and stem weight and tiller number. The early inoculated plants, which responded and recovered more rapidly than later treated ones, suffered a loss in grain yield and this was related to the amount of disease, the loss in green leaf area and the reduction in unit leaf rate.