Effects of Field Application of Tebuconazole on Yield, Yield Components and the Mycotoxin Content of Fusarium-infected Wheat Grain

Winter wheat cultivar Basalt was artificially inoculated with Fusarium culmorum at the end of anthesis and treated with the systemic fungicide tebuconazole (Folicur^®) a few days before and/or after inoculation. Check plots remained uninoculated and unsprayed. Head infections, yield, yield components and the percentage of Fusarium‐ infected kernels were determined. Artificial Fusarium inoculation lowered yield significantly by 24.2‐45.0%. Any fungicide treatment saved yield, thousand grain weight and kernel numbers per head. Pre‐infectional application of tebuconazole was superior to application carried out post‐infection. Moreover, the fungicide controlled deoxynivalenol (DON) synthesis in the field to a considerable extent, and enabled good control of Fusarium head blight, glume blotch and the percentage of Fusarium‐infected kernels. The levels of Fusarium kernel infection after harvest clearly reflected the DON content of w heat grain.     

冬大麦花后穗部氮素积累的特征分析及动态模拟

以扬饲麦3、扬饲麦1和扬农啤2号等3个大麦品种为供试材料，构建了冬大麦花后穗部氮素积累的动态模型，即Richards方程W=A／（1＋be^-kt）^m,定量分析表明，方程的积累速率参数k和形状参数m相对稳定，分别取值0．240481和0．364499．终极积累量A与大麦花前穗部氮含量N呈幂函数关系．A=0．0034e^127.79N；初值参数b与大麦花前穗部氮含量N呈指数函数关系．b=le-24N^-14,978．运用苏啤3号的实测结果对模型进行了检验．结果表明，大麦花后穗部氮积累的模拟值和实测值的绝对误差都在7mg／株以内，误差最小为0．066mg／株，最大的为6．321mg／株；平均差平方和的根值（Root mean square error，RMSE）在5mg／株之内，最大为4．768mg／株，最小为2．058mg／株．模拟值与实测值间显示出较好的一致性．     

The Effects of Grain Nitrogen and Applied Nitrate on Growth, Photosynthesis and Protein Content of the First Leaf of Barley Cultivars

Five cultivars of barley with widely differing grain nitrogencontents were compared. In the absence of exogenous nitratesupply plants grown from high nitrogen grain showed a more rapidleaf emergence, greater leaf size, especially of the first leaf,higher photosynthetic rate and greater total souble proteinand Fraction 1 protein content of the first leaf, than plantsgrown from low nitrogen grain. However, early supply of nitrateto plants grown from low nitrogen grain enabled these to performas well as those from grain with a high nitrogen content. Regressionanalysis showed that Fraction 1 content of the first leaf isclosely correlated with grain nitrogen which exerts a progressivelygreater effect on content of this protein as application ofexogenous nitrate is delayed. The more rapid photosyntheticrate of plants grown with high nitrogen, and the consequentgreater rate of dry matter accumulation, is attributable mainlyto effects of nitrogen availability on leaf area and much lessto effects on leaf protein.     

Genetics of Powdery Mildew Resistance in Barley

A comprehensive, critical review on the present knowledge regarding the genetics of resistance of barley to the powdery mildew fungus is presented. The review deals with six kinds of resistance: Race-specific resistance; Mlo resistance; partial resistance; induced resistance; passive resistance; and non-host resistance. Most of the sections are subdivided into: phenotype of the interaction; resistance mechanisms; and genetics. A distinction is made between three groups of genes involved in the defense of plants to diseases: those that serve exclusively to mediate resistance; those that are mobilized to strengthen the plants' defense; and those that serve exclusively functions other than disease defense, but may bring about resistance. The more than 200 gene symbols assigned to race-specific mildew resistance genes over time are summarized and revised to 85 symbols that may be considered valid.     

Effects of Strigolactones on Grain Yield and Seed Development in Rice

Journal of Plant Growth Regulation - Strigolactones (SLs) are well known as a class of endogenous phytohormones that regulate tiller bud outgrowth. Reduction of inorganic phosphate (Pi) induces the...     

Grain Yield of Pennisetum americanum Adjusts to Nitrogen Supply by Changing Rates of Grain Filling and Root Uptake of Nitrogen

Coaldrake, P. D., Pearson, C. J. and Saffigna, P. G. 1987. Grainyield of Pennisetum americanum adjusts to nitrogen supply bychanging rates of grain filling and root uptake of nitrogen.–J.exp. Bot 38: 558–566. Pearl millet (Pennisetum americanum(L.)Leeke) was grown in containers at three constant rates of nitrogensupply or with the nitrogen supply increased from the lowestto the highest rate during panicle differentiation or at anthesis.We measured the rate and duration of nitrogen and dry weightgain by individual grains and nitrogen (¹⁵N) uptake by rootsand its distribution during grain filling. The total amountsof nitrogen and dry weight in all grain per plant at the lowestnitrogen supply were 8% and 14% respectively of plants growncontinuously at the highest rate of nitrogen. This was becauselow rates of nitrogen supply reduced grain number, mean grainweight and the nitrogen content of each individual grain. Theamino acid composition of the grain protein was affected onlyslightly by nitrogen treatments. Rates of grain growth were sensitive to nitrogen supply whereasthe duration of nitrogen movement to the grain was not. Nitrogenuptake by roots continued throughout grain filling; rates ofuptake per g root in plants given least nitrogen were one-halfthose of plants given the highest amount of nitrogen. A changefrom lowest to highest nitrogen supply at panicle differentiationincreased the uptake of nitrogen by roots and the rates of growthof individual grains, to the rates observed in plants whichhad been supplied continuously with the highest nitrogen. Whenthe change in supply was made at anthesis there was rapid movementof nitrogen into the plant but this was not translated intomore rapid grain growth. Key words: Nitrogen supply, Pennisetum americanum, grain yield, root uptake     

The Effect of Applications of a Synthetic Cytokinin on Shoot Dominance and Grain Yield in Spring Barley

Spring barley cv Ark Royal was grown in pots in the open, andsoil drenches containing 6-benzyl-aminopurine were repeatedlyapplied during the pre-heading phase starting either ‘early’when the main shoot apex had reached the glume primordium stage,during tillering, or ‘later’ at the anther primordiumstage, at the start of stem elongation Although grain yield was unaffected by the ‘late’cytokinin treatments, it was increased by up to 57 per centby the ‘early’ treatments. The increase was dueto greater grain yields of the smaller shoots of each plantthere was no effect on the yields of the two largest shootsor on the total number of fertile shoots The increased grain yield of these smaller shoots was attributableto increased weights of their individual kernels, especiallyin the basal and distal parts of the ears such that a greateruniformity of kernel size within the ear was achieved Thus the cytokinin treatment increased uniformity both betweenshoots and between spikelets within the ears Hordeum vulgare L, spring barley, cytokinin, 6-benzylaminopunne, shoot dominance, harvest index, grain yield     

Consequences of Wheat Breeding on Nitrogen and Phosphorus Yield, Grain Nitrogen and Phosphorus Concentration and Associated Traits

Several studies have analysed the effects of wheat breedingon dry matter accumulation and partitioning, but little hasbeen done to understand the effects on nutrient economies. Theobjective of this study was to identify the changes producedby wheat breeding in the economy of nitrogen and phosphorusunder field conditions. Two experiments were carried out withseven genotypes (including a commercial hybrid) representingdifferent eras of plant breeding. Wheat breeding has increased grain nitrogen and phosphorus yieldbut total absorbed nutrients have not shown any trend duringthis century. The main attribute closely related to the increasein grain nitrogen and phosphorus yields was their harvest indices.The higher nutrient partitioning in the newer cultivars wasassociated with lower grain nitrogen and phosphorus concentrationsin their grains. Therefore, there was a negative effect of geneticimprovement in grain nitrogen and phosphorus concentrations.The main cause for the decreased concentration of these nutrientsin the grains of the modern cultivars appeared to be a dilutionby an even more increased dry matter partitioning. It is suggestedthat future breeding should be aimed to select for higher nitrogenuptake as a way to increase the level of this nutrient in grain.Copyright1995, 1999 Academic Press Triticum aestivum L., wheat breeding, genetic improvement, nitrogen, phosphorus, wheat, grain nitrogen concentration, grain phosphorus concentration     

Effects of Nitrogen Deficiency on the Absorption of Nitrate and Ammonium by Barley Plants

When young barley plants which had been supplied with nitratewere deprived of this source of N, an enhanced capacity forabsorption of either nitrate or ammonium ions developed, reachinga maximum in about 3 d under the particular experimental conditionsused. The net uptake rate of either nutrient was then approximatelythree times that in plants which had received nitrate throughout.Likewise, withholding external N from plants previously growingwith ammonium caused a 2.4-fold increase in their subsequentcapacity to absorb that ion, compared with control plants grownwith an uninterrupted ammonium supply. Accelerated nitrate uptakein N-starved plants was not accompanied by additional phosphateor sulphate absorption, but the plants had the capacity to absorbmore potassium, whether or not ammonium was also present inthe solution. Indirect evidence from analyses of root tissuesuggests that these responses to mild N-stress may depend onsome property of an N fraction which does not include nitrateor ammonium. Hordeum vulgare, barley, nitrogen, ammonium, nitrate, N-deficiency, absorption     

Effects of Radiation and Temperature on Tiller Survival, Grain Number and Grain Yield in Winter Wheat

Effects of the environment on shoot survival were studied inwinter wheat cv. Avalon grown in microplots at a density of247 plants m^–2. The incident radiation and mean temperaturewere altered during one of three periods of between 14 and 29d duration, the first (P1) starting at the end of tiller productionand the last (P3) finishing near the end of the tiller deathphase, about three weeks before anthesis. Plants were giventemperature and radiation treatments in growth rooms in twoexperiments and extra light outdoors in a third experiment:they were at other times grown outdoors. Increasing radiation by between 60 and 100 per cent during P1had negligible effects on shoot number; during P2 it alwaysdelayed tiller death but increased final ear number in onlyone experiment; during P3 it consistently increased ear numberby up to 100 m^–2. Increased radiation always increasedcrop dry weight immediately after treatment but only sometimesdid this increase persist to maturity. Grain dry weight wasincreased by treatment during P3 of one experiment. Increasingthe temperature by 4 C decreased shoot number, usually onlytemporarily, by hastening death of some tillers. Warmer temperaturesdecreased crop growth after, but not during, treatment and decreasedgrain dry weight. Radiation and temperature rarely interacted. Variation in grain yield within and between experiments relatedwell to variation in number of grains m^–2, which in turnrelated to variation in ear dry weight at anthesis. Triticum aestivum L., wheat, radiation, temperature, tillers, grain yield, grain number     

Distribution of the Products of Photosynthesis between Powdery Mildew and Barley

The photosynthetic assimilation of ¹⁴CO₂ has been studied in healthy and mildew-infected barley. The parasite was separated from the host by removing the mycelium with a camel's hair brush. The ethanol soluble metabolites of the parasite, infected host and healthy host were extracted, separated by paper chromatography and individually identified. From this work it appears that there is a rapid movement of label from host to parasite mainly in the form of sucrose which is then quickly metabolized into many compounds. The majority is converted into mannitol, and lesser amounts are converted into trehalose, arabitol, aspartic acid, and glutamic acid. In conidia the major carbon reserve is arabitol instead of mannitol, with lesser amounts of trehalose and mannitol.

Photosynthetic uptake of ¹⁴CO₂ by the complex decreases steadily after inoculation as compared with healthy leaves. However, the ethanol soluble metabolites of the infected host tissue differ only slightly from those of healthy host tissue. The major differences are a slight decrease in the amount of sucrose and increases in malic acid and serine.

     

Metabolism of Ammonium Ion and Glutamate in Relation to Nitrogen Supply and Utilization during Grain Development in Barley

Changes in the activity of a number of enzymes concerned with amino acid synthesis and metabolism were recorded for the endosperm, testa pericarp, and embryo of developing barley (Hordeum distichum L.) grains. Both glutamate-pyruvate transaminase and glutamate-oxaloacetate transaminase activities were present in all tissues and at all ages examined. Glutamate dehydrogenase activity was largely confined to endosperm while glutamine synthetase activity was mainly in the testa pericarp.     

Effects of Induced Resistance on Disease Severity/Yield Relations in Mildewed Barley

Field experiments showed that the treatment of winter barley with microbial metabolites produced by a Bacillus subtilis strain led to increased yields in spite of a remaining mildew infection. Disease severity/yield relations obtained on a single tiller basis for either mildew infection at EC 75 or area under disease progress curve (AUDPC) were negatively correlated for untreated plants (R²= 89%, 94%) while this relation did not exist for inducer-treated ones (R²= 10%, 13%). Despite an increasing infection density. yields of main tillers of inducertreated plants were not decreased. On the other hand area under green leaf area curve (AUGLAC) showed a higher correlation with grain yield (R²= 89%) of inducer-treated plants. Possible explanations for the mitigated damaging effect of powdery mildew were expected in carbohydrate metabolism. especially carbohydrate formation and translocation. Assimilation rates of flag leaves of inducer-treated barley with similar infection densities to those of untreated plants were increased over a prolonged period and even exceeded those of non infected ones. In inducer-treated plants the export of ¹⁴CO₂ from flag leaves into ears remained unimpaired by mildew infection and the allocation of assimilates to grains was highest at late stages of grain filling. Obviously plants were stimulated by inducer treatments to compensate for the damaging effect of powdery mildew and to tolerate mildew infection without yield loss.