Chemical alteration in wheat (Triticum aestivum) shoot induced by mefluidide and defoliation

Mefluidide [N-2(2,4-dimethyl-5-((trifluoromethyl)sulfonyl)amino)phenyl)acetamide] was applied to winter wheat (Triticum aestivum) to determine the alterations in shoot chemical composition and the value of the changes to a wheat-based forage system in field and controlled-environment chamber experiments. Mefluidide, applied at rates between 0.1 and 0.25 kg/ha during full tiller stage (Feekes stage 4), slowed down the rate of cellulose deposition in wheat shoot and reduced neutral-detergent fiber fractions. Mefluidide decreased the rate of nitrogen decline with advancing maturity of treated plants when compared to untreated ones. Mefluidide also reduced cellulose deposition and maintained high nitrogen contents in regrowth shoot tissues in addition to the effect produced by mechanical defoliation. Mefluidide, applied during jointing stage (stage 5), also retarded wheat maturation as the chemical maintained shoot chemical characteristics equivalent to those of earlier stages of development. Mefluidide did not alter significantly shoot chemical composition when applied at boot stage (stage 10), compared to untreated wheat. Based on the experimental results, mefluidide may be a management tool to alter timing of plant development. The delay in maturation and maintenance of vegetative quality longer into the spring attained with mefluidide may suggest a beneficial role of the chemical in a dual-purpose wheat production system that favors forage utilization.Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Influence of mefluidide on growth,development, and cell wall digestibility of sorghum

Application of mefluidide (N-[2,4-dimethyl-5-([(trifluoromethyl)sulfonyl]amino) phenyl]acetamide) inhibits plant development in perennial grasses. This study examined the effect of mefluidide on the morphological development and digestibility of sorghum. In the greenhouse, 5.9 × 10^–5 g active ingredient (a.i.) plant^–1 applied at the seedling, eight-leaf and boot stages reduced mean plant height 70%, 59%, and 2%, respectively. Heights were also reduced 14%, 15% and 35% by 5.9 × 10^–8, 5.9 × 10^–7 and 5.9 × 10^–6 gram a.i. plant^–1 applied at the eight-leaf stage. Field application of 0.26 or 0.52 kg ha^–1 mefluidide at either the eight-leaf or flagleaf stage reduced mean plant height of all cultivars. Basal tiller numbers increased 319% 28 d, and dry matter production was reduced 65% 42 d following mefluidide application at the eight-leaf stage. Treated stems were 34% higher and treated leaves were 7% higher in cellulase dry matter digestibility than control plants following mefluidide application at the eight-leaf stage. These results indicate that mefluidide application to vegetative stages in sorghum may enhance the forage value of the plants while it inhibits normal plant growth.     

Comparative efficacy of two controlled-release gypsy moth mating disruption formulations

The effects of aerial applications of the gypsy moth sex pheromone, disparlure, on mating disruption and suppression of growth of populations of the gypsy moth, Lymantria dispar (L.), were investigated. Two formulations of disparlure, plastic laminate flakes applied in a single application and polymethacrylate beads applied in two applications, were compared in two separate tests conducted in 1993 and 1994. The beads were applied in two applications spaced 2 weeks apart because preliminary tests had indicated that they released pheromone too rapidly to maintain adequate emission rates throughout the period of male flight. In 1993, the flakes were applied at a rate of 50 g a.i./ha, and the beads were applied at a rate of 15 g a.i./ha for each application. In 1994, the flakes were applied at a rate of 75 g a.i./ha and the beads were applied at rates of 32.5 and 42.5 g a.i./ha for the two applications. Beads with larger average particle size were used in 1994 to prolong disparlure release. The treatments applied in 1993 resulted in >97% reduction in mating and >82% suppression of population growth in the following year. Because of a 1995 collapse of gypsy moth populations in the vicinity of the tests, reliable population growth data were not available for the treatments applied in 1994, but significant mating disruption did occur under both treatments. Based on measurements of residual disparlure after field aging, the flakes released 32 and 48% of their disparlure content during the 6 weeks of male moth flight in 1993 and 1994, respectively. The smaller beads used in 1993 released 75% of their disparlure content, and the larger beads used in 1994 released 52% of their disparlure content, during the 6 weeks of male flight. The biological efficacy data suggest that the bead and flake formulations, as applied in these tests, have similar effects on gypsy moth mating disruption and subsequent population growth. Based on the observed release rates from both 1993 and 1994, a single application of the beads would provide emission rates equal to or greater than those provided by the flakes when applied at an equal dose.     

Carbon Dioxide Exchange Rate and Chlorophyll Content of Turfgrasses Treated with Flurprimidol or Mefluidide

Plant growth regulators (PGRs) are being used increasingly for high maintenance turf production. A greenhouse and growth chamber study was conducted to determine the effect of two PGRs, mefluidide and flurprimidol, on the carbon dioxide exchange rate, chlorophyll content, and specific leaf weight of annual bluegrass and creeping bentgrass. Rate-response and time course studies were conducted. In the rate-response study, increasing flurprimidol rates caused a linear decrease in the carbon dioxide exchange rate (CER). Mefluidide had no effect on the CER in the rate-response experiment but did cause a significant drop in the CER at 4 and 8 days after treatment (DAT) in the time course study. Both PGRs increased chlorophyll content at 16 DAT in the time course study. In the rate-response study, chlorophyll content displayed a quadratic response to an increasing mefluidide rate. The 0.28 kg ha⁻¹ rate of mefluidide increased the chlorophyll content to 46 μg cm⁻² from 21.5 μg cm⁻² for control plants. Both PGRs increased specific leaf weight, although for flurprimidol the effect was significant only at the 0.1 level of probability. PGRs decreased the CER and increased the chlorophyll content and specific leaf weight for both species tested. The physiologic effects measured were short lived, and so the physiologic significance of these changes is difficult to determine without further research. Received September 19, 1996; accepted January 22, 1997     

The effect of chlormequat chloride formulated with choline chloride on the height and yield of winter wheat

Twenty-one field trials were conducted on commercial crops of winter wheat from 1976 through to 1978, with a mixture of 460 g chlormequat chloride and 320 g choline/litre at rates ranging from 0.67 kg to 2.07 kg of chlormequat chloride/hectare. The mean increase in grain yield in the absence of lodging following treatment with chlormequat chloride was 0.31 t/ha, with a greater yield increase where lodging occurred on untreated controls. Chlormequat chloride when applied in mixture with carbendazim fungicide usually resulted in yield increases which were less than the sum of the increases from the two products applied separately. Yield increases following the use of chlormequat chloride were usually greater when used in a traditional system of wheat growing than when used in the Laloux system. Effects of chlormequat chloride on crop height were poorly determined in the dry season of 1976 but there were consistent reductions up to 1.15 kg a.i./ha in 1977. Crop height was reduced by 1.61 kg of chlormequat chloride/ha in 1978.     

Effect of coupled reduced irrigation and nitrogen fertilizer on soil mite community composition in a wheat field

Groundwater and nitrogen fertilizer overuse severely threatens crop productions; thus, current ecological agriculture requires low irrigation and nitrogen fertilizer inputs. The effects of combined reduced irrigation and nitrogen fertilizer addition on soil organism (e.g., mite) community and biodiversity remain poorly understood. We analyzed soil mite community composition, wheat grain yield, and soil characteristics in a 10‐year manipulation experiment with two levels of irrigation (reduced and conventional irrigation) and five nitrogen fertilizer levels (0, 70, 140, 210, and 280 kg N/ha). Reduced irrigation (20% reduction, from 280 to 220 mm) and nitrogen fertilizer (25% reduction, from 280 to 210 kg N/ha) addition did not significantly influence soil mite community and wheat yield. The relative abundances of fungivores and predators showed negative quadratic relationships with wheat yield, while that of plant parasites showed a positive relationship. The relationships between soil mite trophic groups and wheat yield revealed that we can evaluate the impacts of reduced irrigation and nitrogen fertilizer addition from the perspective of soil fauna. Soil mite community composition was altered by soil abiotic factors prior to reduced irrigation and nitrogen fertilizer addition. Overall, moderate reductions of irrigation and nitrogen fertilizer may not threaten to soil mite community and diversity or decrease crop production; in contrast, such reductions will benefit mite community development and the sustainable agriculture.     

Relationship between Mefluidide Treatment and Abscisic Acid Metabolism in Chilled Corn Leaves

Mefluidide, N-(2,4-dimethyl-5[([trifluoromethyl]sulfonyl) amino] phenyl)acetamide, a synthetic plant growth regulator, was capable of triggering an increase in endogenous free abscisic acid content when corn (Zea mays L.) plants were grown in a nonstress, day/night, temperature regime (26°C) with sufficient moisture supply. The relevance of such an abscisic acid increase prior to chilling exposure and the water relations during chilling are discussed in reference to the mefluidide protection of the chilled corn plants.     

Evaluation of the pear ester kairomone as a formulation additive for the granulovirus of codling moth (Lepidoptera: Tortricidae) in pome fruit

(E,Z) -2,4-decadienoate (pear ester) is a larval kairomone for the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Orchard studies were conducted in 2005 and 2006 in apple, Malus domestica Borkhausen, and pear, Pyrus communis L., to evaluate a 5% active ingredient (AI), microencapsulated formulation of pear ester (PE-MEC) as an insecticidal additive for the codling moth granulovirus (CpGV). Although CpGV applied at 5-15-d intervals at commercial rates (2.2 X 10(12)-10(13) granules per ha) killed the majority (82-94%) of larvae found inside infested fruit, it did not eliminate significant damage, i.e., 30-92% fruit injury at harvest versus 51-82% in controls. PE-MEC treatments had significant but inconsistent results in our tests. In apple (mixed cultivars), PE-MEC (3.7-4.7 g [AI] /ha) plus CpGV reduced the percentage of fruit injured during the second but not the first larval generation, compared with CpGV alone, but there no was no additional population reduction (live larvae collected from infested fruit and tree bands). In 'Bartlett' pear, PE-MEC (3.7 g [AI] /ha) plus CpGV significantly increased larval mortality and reduced deep fruit entries at harvest over CpGV alone in 2006, but similar improvements were not observed in 2005 when a lower rate (1.5 g [AI] /ha) was tested. Surprisingly, compared with untreated controls, the PE-MEC formulation alone also reduced fruit injury (mid-season in Bartlett) and larval survivorship inside infested fruit at harvest (2006 apple tests and both years in Bartlett). Although pear ester seems amenable as a kairomonal adjuvant for use with insecticides, our inconsistent data with CpGV in apple and pear suggest practical improvements in formulation and application strategies (e.g., to optimize and maintain attractive release rates) are needed.     

Bean leaf beetle (Coleoptera: Chrysomelidae) management for reduction of bean pod mottle virus

Bean pod mottle virus (BPMV) is a management concern for soybean, Glycine max (L.), producers in the North Central states because it can cause yield loss and reduce seed quality by induction of seed coat mottling. The main vector of BPMV is the bean leaf beetle, Cerotoma trifurcata (Forster). An experiment was conducted in 2000 and 2001 at two locations in northwestern and central Iowa to test three insecticide treatments for suppression of bean leaf beetles, and subsequently, BPMV. Treatments of insecticide applications with lambda-cyhalothrin were 1) a single early-season application (23 g [AI] /ha) (2.5 oz/acre) at the VE-VC soybean developmental stage; 2) two early-season applications, the first the same as treatment 1 and a second at the same rate 9-13 d later; 3) a single early-season application the same as treatment 1, followed by a mid-season application (28 g [AI] /ha (3.2 oz/acre) at approximately R2 (flowering, near 15 July); and 4) an unsprayed control. Application of lambda-cyhalothrin after soybean emergence and again as first-generation bean leaf beetles emerged in northwestern Iowa in 2000 (treatment 3) significantly reduced beetle densities through mid-season, BPMV field incidence by 31.5%, and seed coat mottling by 31.2%, compared with the unsprayed control. Similar effects were measured at the same location when insecticide was applied twice at early season (treatment 2). Yield was 453.7 kg/ha (6.74 bu/acre) greater in treatment 2 and 525.20 kg/ha (7.80 bu/acre) greater in treatment 3 than in the unsprayed control at the northwestern site in 2000. At both locations in 2001 fewer treatment effects were observed, which was likely related to lower beetle populations in that year. Early-season insecticide sprays targeted at overwintered beetles on VC-VE reduced the initial population of vector insects and may have contributed to a lower first-generation population because of reduced overwintered beetle oviposition. In 1 year at one location there was a benefit to an additional mid-season insecticide spray, although effectiveness of spraying at this time could vary based on the magnitude of the vector population.     

Some effects of applied sodium and potassium chloride on yellow rust in winter wheat

In glasshouse experiments with plants in pots, applications of potassium chloride to the soil at 0.5 g/plant, 4 days before inoculation with Puccinia striiformis, decreased the severity of yellow rust on several winter wheat cultivars in comparison with untreated plants. Conversely, yellow rust was encouraged by applications of sodium nitrate. Sodium chloride in solution (8.6 g/l) reduced yellow rust when applied to the soil at the rate of 20 ml/plant but not when it was sprayed on to the leaves. In small-plot field experiments, sodium and potassium chlorides applied to the soil as dry powders in the spring at rates of 376, 1130 or 2260 kg/ha, significantly decreased the severity of yellow rust on most of the winter wheat cvs examined at each rate. The chlorides at these rates did not adversely affect the overall growth or yield in the absence of yellow rust.     

Sensitivity of the Entomogenous Fungus Beauveria bassiana to Selected Plant Growth Regulators and Spray Additives

Mefluidide was the only one of four plant growth regulators that caused little to no significant inhibition of in vitro germination and growth of the entomogenous fungus Beauveria bassiana. Silaid, paclobutrazol, and flurprimidol significantly inhibited germination and growth. Mortality of fall armyworm, Spodoptera frugiperda, resulting from B. bassiana was significantly reduced when larvae were exposed to conidia plus soil treated with paclobutrazol. Larval mortality resulting from conidia plus soil treated with mefluidide did not differ significantly from mortality resulting from untreated conidia. Triton CS-7 was the only one of eight spray adjuvants that significantly inhibited germination of B. bassiana conidia.     

Influence of Poultry Litter Applications on Nematode Communities in Cotton Agroecosystems

The effects of the application of poultry litter at 0.0, 6.7, 13.4, and 20.1 tons/ha on population changes during the growing season on nematode communities were evaluated in two cotton production fields in North Carolina. Numbers of bactivorous nematodes increased at midseason in response to the rate at which litter was applied but decreased with increasing litter application rates at cotton harvest. Numbers of fungivores at cotton harvest were related positively to the rate of litter applied, and this affected a positive increase in the fungivore-to-bacterivore ratio at this sampling date. The rate at which poultry litter was applied resulted in an increase in the bacterivore to plant-parasite ratio, and this corresponded with increased cotton lint yield. Trophic diversity was increased by litter application rate at cotton harvest at one location but not at another. The plant-parasite maturity index was greater consistently at one site than at a second site where the Hoplolaimus columbus population density was above the damage threshold for cotton. The population density of H. columbus was suppressed with increasing rates of poultry litter application, but other plant-parasitic nematodes were affected marginally.     

Development of selective aphicide treatments for integrated control of summer aphids in winter wheat

Field experiments on the use of recommended and reduced application rates of aphicides for control of summer aphid infestations on winter wheat have been done at five sites each year from 1990 to 1992. The experiment compared sprays of pirimicarb at recommended rate (140g a.i. ha^-1) and reduced rate (25 g a.i. ha^-1) and of alphacypermethrin at recommended rate (15 g a.i. ha^-1) and one third recommended rate (5 g a.i. ha^-1), each applied either at flag leaf emergence or at flowering. Aphid infestations were allowed to develop naturally and were measured at critical growth stages. In 1990, overwintered aphid infestations, together with established populations of parasitoids, were detected at four of the five sites when the first assessment was made in April. Parasitoids provided sufficient aphid control to prevent yield loss at two sites, without pesticide applications. At three sites both aphicides gave similar levels of control and yield response at both recommended and reduced application rates. In 1991 and 1992 no overwintered aphids were detected in the crops and aphid infestations developed much later. Aphicide applications gave significant yield responses at four sites in 1992. Recommended rates gave better control of aphids than reduced rates. There was no significant difference in the yield response obtained with different rates of aphicide.     

Winter nitrogen fertilization of loblolly pine seedlings

Loblolly pine (Pinus taeda L.) seedlings were nitrogen fertilized during winter in a bare root forest tree nursery located in the coastal plain of the southeastern United States. Total application rates were 0, 50, 100, and 200 kg/N/ha applied in split applications 4 weeks apart in January and February. Seedlings were lifted and outplanted in March, 4 weeks after the second fertilization and measured at 3 and 6 months after outplanting. No seedling morphological differences were encountered at the time of lifting and outplanting although seedling shoot nitrogen content was 28% greater in the highest fertilization treatment compared to the check. Shoot nitrogen concentrations fell after outplanting regardless of treatment, decreasing from an average of 1.51% across all treatments at the time of planting to 0.64% at 6 months after planting. When measured at 6 months after outplanting, seedling dry weight and height growth after planting was shown to increase by 12% and 24%, respectively, for the high nitrogen treatment. This and other studies across a variety of sites have found positive post-outplanting seedling growth response after nutrient loading in the nursery.     

Influence of adjuvants and plant growth regulators on herbicide performance in honey mesquite

Addition of surfactant I (trimethylnonylpolyethoxyethanol) or surfactant II (4-isopropenyl-1-methyl-cyclohexane) at 1.0 and 0.6% (v/v) of the spray solution enhanced the phytotoxicity of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), the triethylamine salt of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid}, picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid)] applied at 0.14 kg ae/ha to greenhouse-grown honey mesquite (Prosopis glandulosa Torr.). Application of benazolin [4-chloro-2-oxo-3(2H)-benzothiazolacetic acid] increased the phytotoxicity of all herbicides, but ethephon [(2-chloroethyl)phosphonic acid] and mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide} were usually ineffective. Clopyralid + picloram, triclopyr, or 2,4,5-T applied in 1:1 combinations at 0.07 + 0.07 kg/ha were usually equally or more effective than any one of the herbicides applied alone at 0.14 kg/ha. Adjuvants did not enhance the phytotoxicity of picloram, triclopyr, or 2,4,5-T on field-grown honey mesquite but sometimes did with clopyralid.     

Short-term immobilisation and crop uptake of fertiliser nitrogen applied to winter wheat: effect of date of application in spring

Previous studies on the fate of fertiliser nitrogen applied to winter wheat in temperate climates have shown that nitrogen (N) applied early, at tillering for wheat, was less efficiently taken up than N applied later in the growth cycle. We examined the extent to which the soil microbial N immobilisation varied during the wheat spring growth cycle and how microbial immobilisation and plant uptake competed for nitrogen. We set up a pulse-15N labelled field experiment in which N was applied at eight development stages from tillering (beginning of March) to anthesis (mid-June). Each application was 50 kg N ha-1 as 15N labelled urea except for the first application which was 25 kg N ha-1. The distribution of fertiliser 15N in shoots, roots, mineral and organic soil N was examined by destructive sampling 7 and 14 days after each 15N pulse. The inorganic 15N pool was almost depleted by day 14. The N uptake efficiency increased with later applications from 45% at tillering to 65% at flowering. N immobilisation was rather constant at 13–16% of N applied, whatever the date of application. The increase in plant 15N uptake resulted in an increase in the total 15N recovery in the plant-soil system (15N in soil +15N in plant), suggesting that gaseous losses were lower at the later application dates.     

Movement of simazine in runoff water and weed control from citrus orchard as affected by reduced rate of herbicide application

Simazine (6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine) and diuron (N'-(3,4-dichlorophenyl)-N,N-dimethylurea) are applied as pre-emergence herbicides to control weeds in over 45,000 hectare of citrus in the San Joaquin Valley of California. Growers usually apply 2.0 kg active ingredient (ai) ha(-1) simazine and 2.0 kg ai ha(-1) diuron together in the fall and winter seasons. Surface water and groundwater contamination, ecological, and health damage have led to increased regulatory attention and a search for changes in current weed management practices. Reduced application rate of simazine on runoff losses generated by simulated rainfall was studied in experiment 1. Treatments included a control without herbicide application and application of herbicides at 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1). Three generated runoff events were produced using simulated rainfall with 540 l water. For each simulated rainfall event, the simazine concentration in runoff water was greatest at the first volumetric sampling interval, decreasing gradually in subsequent samples. Simazine concentration in runoff water for the three runoff events was undetectable for the control treatment. For the first simulated rainfall event, simazine concentrations in runoff water averaged 0.55, 1.07, 1.27, and 2.12 mg l(-1) for treatments receiving 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1) herbicide application, respectively; simazine concentration in runoff water from the second event one week later averaged 0.16, 0.27, 0.36, and 0.58 kg ai ha(-1) and two weeks later the concentration was reduced to 0.05, 0.10, 0.14 and 0.22 mg l(-1), respectively. Total simazine mass recovered in runoff water from the three simulated rainfall events was estimated approximately 13.8, 26.3, 32.3 and 53.8 g ha(-1) for the treatments receiving herbicide application at 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1), respectively. Field evaluation of weed density showed that pre-emergence herbicides applied at reduced rates (1.0 and 1.25 kg ai ha(-1)) were as effective as the standard rate (2.0 kg ai ha(-1)) for weed control in experiment 2.     

Barrier spraying to control the malaria vector Anopheles albimanus: laboratory and field evaluation in the Dominican Republic

Abstract. To develop a new strategy for control of exophilic/exophagic malaria vectors which rest on peridomestic foliage, Anopheles albimanus was used for laboratory bioassays of mosquito adulticides applied to various vegetation types. Of the three classes of insecticide tested, the pyrethroid (permethrin at 112 g/ha) showed greater foliar persistence than either the carbamate (bendiocarb at 340g/ha) or the organophosphorus compound (malathion at 277g/ha). Field evaluation of barrier spraying against An.albimanus was evaluated in rural villages of southwest Dominican Republic during 1989. The pyrethroid deltamethrin was sprayed aerially for ultra-low volume application at treatment rates of 17-19ga.i./ha in a radius of 500m around two villages. An.albimanus were monitored by light-traps and human bait collections at both treated villages, compared with two similar untreated villages, up to 9 nights post-treatment. Densities of female An.albimanus were significantly reduced in the sprayed villages for at least 8 or 9 nights. Further evaluation of barrier spraying is recommended to determine optimal pyrethroid formulations and applications rates, their impact on non-target fauna and efficacy against malaria transmission.     

Selenium in Australia: selenium status and biofortification of wheat for better health.

Selenium (Se) is an essential micronutrient for humans and animals, but is deficient in at least a billion people worldwide. Wheat (Triticum aestivum L.) is a major dietary source of Se. The largest survey to date of Se status of Australians found a mean plasma Se concentration of 103 microg/l in 288 Adelaide residents, just above the nutritional adequacy level. In the total sample analysed (six surveys from 1977 to 2002; n = 834), plasma Se was higher in males and increased with age. This study showed that many South Australians consume inadequate Se to maximise selenoenzyme expression and cancer protection, and indicated that levels had declined around 20% from the 1970s. No significant genotypic variability for grain Se concentration was observed in modern wheat cultivars, but the diploid wheat Aegilops tauschii L. and rye (Secale cereale L.) were higher. Grain Se concentrations ranged 5-720 microg/kg and it was apparent that this variation was determined mostly by available soil Se level. Field trials, along with glasshouse and growth chamber studies, were used to investigate agronomic biofortification of wheat. Se applied as sodium selenate at rates of 4-120 g Se/ha increased grain Se concentration progressively up to 133-fold when sprayed on soil at seeding and up to 20-fold when applied as a foliar spray after flowering. A threshold of toxicity of around 325 mg Se/kg in leaves of young wheat plants was observed, a level that would not normally be reached with Se fertilisation. On the other hand sulphur (S) applied at the low rate of 30 kg/ha at seeding reduced grain Se concentration by 16%. Agronomic biofortification could be used by food companies as a cost-effective method to produce high-Se wheat products that contain most Se in the desirable selenomethionine form. Further studies are needed to assess the functionality of high-Se wheat, for example short-term clinical trials that measure changes in genome stability, lipid peroxidation and immunocompetence. Increasing the Se content of wheat is a food systems strategy that could increase the Se intake of whole populations.     

Postanthesis remobilisation and losses of nitrogen in wheat in relation to applied nitrogen

A ¹⁵N leaf feeding technique was used to measure the extent of remobilisation and loss of nitrogen (N) that had been accumulated prior to anthesis in wheat plants that received three rates of N fertilizer. Uptake of postanthesis N to the heads was reduced as the quantity of applied N was increased. This reduction of postanthesis N uptake did not affect the quqntity of N in the heads because the loss of preanthesis accumulated N was reduced and the extent of remobilised preanthesis N increased at higher rates of N application. At the lowest rate of N application the increase in ¹⁵N in the heads of fertile shoots arose chiefly from the remobilisation of N in the stem supporting the head. At higher rates of N application this source of N was increasingly supplemented by N remobilised from infertile tillers and roots.