The effect of a mixture of seed-borne Microdochium nivale var. majus and Microdochium nivale var. nivale infection on Fusarium seedling blight severity and subsequent stem colonisation and growth of winter wheat in pot experiments

Greenhouse experiments were conducted in order to determine the impact of seed-borne Microdochium nivale var. nivale and var. majus inoculum, and seed treatment with a carboxin+thiram mixture, on the development of seedling blight, and on subsequent stem colonisation and growth of winter wheat (cv. Cadenza). Experiments were conducted at temperatures favourable (3°C) and unfavourable (22°C) to M. nivale. Seed-borne inoculum resulted in seedling blight symptom development when plants were grown at 3°C, but not when plants were grown at 22°C. For seedlings grown at 3°C, plants arising from heavily blighted seedlings developed more severe symptoms of stem colonisation, when compared with those arising from seedlings from carboxin+thiram treated seeds. In addition, the vigour of such plants (assessed by determining the number of tillers and ears per plant, stem length, green leaf area, dry weight and yield) was also significantly lower than for plants arising from carboxin+thiram treated seeds. Microdochium nivale var. majus and var. nivale appeared to have little effect on plant vigour from seedlings grown at 22°C. This is the first recorded incidence of seedling blight affecting subsequent plant growth. Microdochium nivale var. majus and var. nivale stem colonisation increased from growth stage (GS) 40–49 to harvest in plants raised from seedlings grown at both temperatures. Microdochium nivale var. majus and var. nivale were isolated from the second node at GS 40–49 and the third node at harvest of plants from seedlings grown at 3°C. For plants from seedlings raised at 22°C, M. nivale var. majus and var. nivale were isolated from the first node at GS 40–49 and the second node at harvest. Carboxin+thiram seed treatment decreased the extent and severity of stem colonisation on plants from seedlings grown at 22°C.     

Influence of long-term conservation tillage on soil and rhizosphere microorganisms

 In long-term field experiments on sandy loam and loamy sand soils, the influence of conservation and conventional tillage on soil and rhizosphere microorganisms was studied. Conservation tillage stimulated rhizosphere bacteria on winter wheat, winter barley, winter rye and maize in different soil layers. Particularly the populations of Agrobacterium spp. and Pseudomonas spp. were increased. On the sandy loam, N₂ fixation and nodulation of pea plants were significantly increased. No influence of different soil tillage was determined on the colonization of the rhizosphere by mycorrhiza and saprophytic fungi. Stubble residues infected with Gaeumanomyces graminis were infectious for a longer time on the soil surface than after incorporation into the soil. Received: 10 March 1998     

Phytodiversity for Metals in Plants Grown in Urban Agricultural Lands Irrigated with Untreated City Effluent

In developing countries, farmers use effluent as a source of irrigation and nutrients and the government takes this practice as a viable option for disposal. Sewage samples have hazardous electrical conductivities (EC), sodium adsorption ratios (SARs), and residual sodium carbonate (RSC) for irrigation, but metals were close to upper permissible limits. The EC of saturated soil paste extract (EC_e) ranged from 2.18 to 4.02 dS m^–1 and soil SAR 7.72 to 16.00 in soils 0.2 m deep. Average cadmium (Cd), nickel (Ni), lead (Pb), zinc (Zn), and copper (Cu) in soils ranged from 0.02 to 0.13, 0.00 to 4.45, 2.27 to 4.57, 0.71 to 13.76, and 3.17 to 10.37 mg kg^–1, respectively. Plants acquired metal contents greater than in raw sewage or soils. The wide biodiversity regarding metals in shoots of natural and planted vegetation that receives raw sewage is of practical significance. It seems imperative to study under controlled conditions various plants' metal tolerance and mechanisms of metal partitioning among plant parts.     

Amino acid composition and chemical evaluation of protein quality of cereals as affected by insect infestation

A significant decrease in essential amino acids of wheat, maize and sorghum was observed due to grain infestation caused by mixed populations ofTrogoderma granarium Everts andRhizopertha dominica Fabricius (50:50). Non-essential amino acids were also adversely affected. Among the essential amino acids, maximum reduction was found in methionine, isoleucine and lysine in infested wheat, maize and sorghum grains, respectively. Lysine, with lowest chemical score in uninfested and infested grains of three cereals, is the first limiting amino acid. Insect infestation caused significant (p<0.05) reduction in the chemical score of all the essential amino acids, yet did not change the position of first and second limiting amino acids in wheat and sorghum. However, in case of maize, isoleucine became the second limiting amino acid. Infested grains also showed substantial reduction in essential amino acid index, calculated biological value and requirement index.     

Productivity of organic and conventional arable cropping systems in long-term experiments in Denmark

A field experiment comparing different arable crop rotations was conducted in Denmark during 1997–2008 on three sites varying in climatic conditions and soil types, i.e. coarse sand (Jyndevand), loamy sand (Foulum), and sandy loam (Flakkebjerg). The crop rotations followed organic farm management, and from 2005 also conventional management was included for comparison. Three experimental factors were included in the experiment in a factorial design: 1) crop rotation (organic crop rotations varying in use of whole-year green manure (O1 and O2 with a whole-year green manure, and O4 without), and a conventional system without green manure (C4)), 2) catch crop (with and without), and 3) manure (with and without). The experiment consisted of three consecutive cycles using four-course rotations with all crops present every year, i.e. 1997–2000 (1st cycle), 2001–2004 (2nd cycle), and 2005–2008 (3rd cycle). In the 3rd cycle at all locations C4 was compared with two organic rotations, i.e. O2 and O4. The O2 rotation in the third cycle included spring barley, grass-clover, potato, and winter wheat, whereas C4 and O4 included spring barley, faba bean, potato, and winter wheat. For the O2 rotation with green manure there was a tendency for increased DM yield over time at all sites, whereas little response was seen in N yield. In the O4 rotation DM and N yields tended to increase at Foulum over time, but there was little change at Flakkebjerg. The DM yield gap between organic and conventional systems in the 3rd cycle varied between sites with 34–66% at Jyndevad, 21–44% at Foulum, and 32–52% at Flakkebjerg. The inclusion of grass-clover resulted in lower cumulated yield over the rotation than the treatment without grass-clover. The use of manure reduced the DM yield gap between conventional and organic systems on an average by 15 and 21%-points in systems with and without grass-clover, respectively, and the use of catch crops reduced the yield gap by 3 and 5%-points in the respective systems. Across all crops the agronomic efficiency of N in manure (yield benefit for each kg of mineral N applied) was greater in O4 compared with O2 for all crops.     

Variations of DON Content in Grain during Wheat Tempering at Different Temperatures

[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two naturally Fusarium-infested wheat samples Youmai 3 and Yangmai 14 were selected as experimental materials. Tempering was carried out at different temperature(15, 25 and 35 ℃) for 48 h. During tempering, wheat grain samples were collected every 8 h. DON contents in tempered grain were measured by HPLC coupled with UV detector. [Result] For Youmai 3, DON contents were in the ranges of 3.94-12.49, 4.26-6.11 and 3.41-7.91 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 32ndhour at 15 ℃, the 8thhour at 25 ℃ and the 32ndhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 175.1%, 27.5% and 7.2%, respectively. For Yangmai 14, DON contents were in the ranges of 0.55-1.56, 0.39-0.77 and 0.57-3.17 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 24thhour at 15 ℃, the 40thhour at 25 ℃ and the 48thhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 94.5% at 15 ℃ and 456.1% at 35 ℃, respectively, whereas it was decreased by 35.0% at 25 ℃. From the point of view of reducing DON level, 15 ℃ was not reasonable for the tempering of both wheat cultivars, and tempering at 35 ℃ for 16 h and tempering at 25 ℃ for 24 h appeared to be desirable for Youmai 3 and Yangmai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.     

Long-term effects of potassium fertilization on yields and fertility status of calcareous soils of south-west France

A long-term field experiment was conducted near Toulouse (south-west France) to verify to what extent increasing fertilizer dressings would increase yields on calcareous soils in a cereals-oilseeds-legumes rotation. Over a 25-year period, withholding K significantly depressed yield once; K inputs affected the total amount of K absorbed at flowering, without subsequent effects on yields.

Exchangeable K content on non-fertilized plots declined slightly over the experimental period, but without reaching levels expected from nutrient balance estimates. Annual applications of K equal to average offtake in grain were adequate to maintain available soil K content at its initial value.

Potassium release kinetics for the exchangeable fraction, evaluated from Ca-resin extraction, clearly discriminated between fertilized and non-fertilized treatments. Both soils exhibited similar patterns for diffusion-controlled K release. These results highlight the role of K reserves readily available in illite-rich calcareous soils and demonstrate the importance of cultural residues in K fertility management.     

Tillage intensity effects on soil properties and crop yields in a long-term trial on morainic loam soil in southeast Norway

Many tillage studies focus primarily on grain crops, whereas other important agricultural crops receive little attention. This paper presents yield results for various crops grown in the tenth to sixteenth year of a long-term tillage trial on loam soil in southeast Norway. Traditional plough tillage was compared with deep and shallow tine cultivation and with minimum tillage, and the residual effects of tillage were measured in the seventeenth and eighteenth years. Soil bulk density, air permeability and other soil conditions were found to be favourable for crop growth on all treatments in the tenth year. The yield levels of cereals (Hordeum vulgare L., Triticum aestivum L. and Avena sativa L.) and potatoes (Solanum tuberosum L.) showed consistent increases of 2–8% with declining tillage intensity, whereas yields of fodder beet (Beta vulgaris L.) were highest after plough tillage. The latter result was thought to be due to lower soil temperatures under reduced tillage. Yields of brassica crops were greatly affected by tillage intensity, owing to a marked reduction of clubroot (Plasmodiophora brassicae Wor.) infection with reduced tillage. Average yields for these crops were 23%, 52% and 59% higher with deep tine cultivation, shallow tine cultivation and minimum tillage, respectively, than with plough tillage. The effects were particularly dramatic in the case of fodder rape (Brassica napus L. ssp. oleifera Sinsk. f. biennis Reichb.) and cabbage (Brassica oleracea L. var. capita L.). Liming raised the yields of some brassica crops but did not influence the effect of tillage.

Soil acidity was measured twice during the trial period and again in the second residual year, and showed values which were 0.1–0.3 pH units lower with reduced tillage than with plough tillage. This rules out the conclusion that the effect of tillage on clubroot was associated directly with acidity. Positive residual effects of reduced tillage systems were found on the yields of both brassicaceous and gramineous crops. Reduced tillage intensity may thus be recommended for all crops studied, with the exception of fodder beet, on morainic loam soils of southeast Norway.     

A Simple Method for Quantitative Estimation of Rhizosphere pH along Root Axes through Visualization

Abstract

Rhizosphere pH is known to be strongly influenced by nitrogen sources and plant species. We have evaluated whether the exposure of the shoot to light affects the pH changes in the rhizosphere of legumes and cereals in the presence of different forms of nitrogen (ammonium, nitrate or both). The pH changes in the rhizosphere were quantified as apparent proton fluxes by image analysis of agar gel containing a pH indicator, in which the root was embedded. In the presence of ammonium or ammonium nitrate, the rhizosphere was alkalized under dark conditions and acidified under light conditions in both cowpea and sorghum. This implied that, in the presence of ammonium, acidification of the rhizosphere is induced by exposure of shoot to light. In the presence of nitrate, both plants alkalized their rhizospheres in the dark, whereas in the light cowpea acidified its rhizosphere although sorghum alkalized it. Light-induced acidification, in the presence of nitrate, was also found in chickpea and adzuki bean, but not in maize. We found, that a particular part of the root axis strongly acidifies the rhizosphere in response to the exposure of shoot to light, especially in legumes. We conclude that rhizosphere pH is strongly affected by the light conditions encountered by the shoot, and the pH changes in response to the light locally along the root axis.     

Biological evaluation of the protein nutritional value in the diets of rats based on cereals and the yeast Yarrowia lipolytica growing on industrial glycerol

Abstract

The aim of this study was to evaluate the influence of the yeast Yarrowia lipolytica growing on industrial glycerol on the protein nutritional value of cereal grains. We prepared six isonitrogenous diets. Three diets were based on cereal grains (wheat, barley, or triticale) plus the yeast Y. lipolytica (consisting of 60% cereal protein and 40% yeast protein). For comparison, three diets were prepared in which the only sources of protein were wheat, barley, or triticale. The tested yeast Y. lipolytica has 46.7% crude protein in dry matter, is rich in lysine (6.22 g/16 gN) and threonine (4.18 g/16 gN), but contains little methionine (1.44 g/16 gN). In our experiment, diets consisting of 40% Y. lipolytica protein +60% wheat, barley, or triticale protein had higher (p<0.01) protein efficiency ratio and net protein ratio than diets based on cereals only. Cereal+yeast diets also have higher biological value and true digestibility (significantly for barley+yeast and triticale+yeast, at p<0.05) compared with diets based only on cereals.