Late Flowering Stage Research Articles

Influence of different Sinorhizobium meliloti inocula on abundance of genes involved in nitrogen transformations in the rhizosphere of alfalfa (Medicago sativa L.)

Inoculation of leguminous seeds with selected rhizobial strains is practised in agriculture to ameliorate the plant yield by enhanced root nodulation and nitrogen uptake of the plant. However, effective symbiosis between legumes and rhizobia does not only depend on the capacity of nitrogen fixation but also on the entire nitrogen turnover in the rhizosphere. We investigated the influence of seed inoculation with two indigenous Sinorhizobium meliloti strains exhibiting different efficiency concerning plant growth promotion on nitrogen turnover processes in the rhizosphere during the growth of alfalfa. Quantification of six target genes (bacterial amoA, nirK, nirS, nosZ, nifH and archaeal amoA) within the nitrogen cycle was performed in rhizosphere samples before nodule formation, at bud development and at the late flowering stage. The results clearly demonstrated that effectiveness of rhizobial inocula is related to abundance of nifH genes in the late flowering phase of alfalfa. Moreover, other genes involved in nitrogen turnover had been affected by the inocula, e.g. higher numbers of amoA copies were observed during flowering when the more effective strain had been inoculated. However, the respective gene abundances differed overall to a greater extent between the three plant development stages than between the inoculation variants.

Effects of Elevated Atmospheric Carbon Dioxide Concentration on Silica Deposition in Rice (Oryza sativa L.) Panicle

The effects of elevated carbon dioxide concentration ([CO2]) on silica deposition on husk epidermis of rice (Oryza sativa L. cv. Akitakomachi) during the flowering stage were investigated in this study. The study was motivated by the concept that the rice yield maybe affected by global warming as a result of elevated [CO2] environment since sterility of rice is related to the panicle silica content that influences transpiration, and elevated [CO2] could affect plant transpiration. Silica deposition analysis was focused on the flowering stage of the rice crop grown hydroponically under two [CO2] conditions: 350 μmol mol-1 (ambient) and 700 μmol mol-1 (elevated). Silica deposition on the husk epidermis from three parts of the panicle at four flowering stages were examined using a scanning electron microscope (SEM) combined with an energy dispersive X-ray microanalyzer (EDX). The results demonstrated that elevated [CO2] significantly suppressed silica deposition on the husk epidermis at the lower part of the panicle, and at the early flowering stage when 1/3 of the panicle emerged from the leaf sheath. In the transverse section analysis of the husk, silica deposition on the husk epidermis under elevated [CO2] was less than that under ambient [CO2] at the late flowering stage. The less silica deposition observed on the husks at the late flowering stage under elevated [CO2] might be related to the suppressed transpiration from the panicle by elevated [CO2] found in a previous study.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Glyphosate Application Timing and Rate for Annual Ryegrass (Lolium Multiflorum) Cover Crop Desiccation

Annual ryegrass has been proposed as a cover crop in the corn–soybean cropping systems of the U.S. Midwest because of its low seed cost, rapid establishment, contribution to soil quality, weed suppressive abilities, and susceptibility to common broad-spectrum herbicides. However, cover crops can reduce the subsequent main crop yield by creating unfavorable germination and emergence conditions, harboring pests, and if not controlled, competing with the main crop. This study, conducted in Illinois, Oregon, and Tennessee, investigated the efficacy of glyphosate for annual ryegrass winter cover crop removal. Glyphosate at 415, 830, and 1,660 g ae/ha was applied to annual ryegrass at late tiller, second node, boot, and early flowering stages. Annual ryegrass control was consistently maximized with the highest glyphosate rate applied at the boot or early flower stage. Annual ryegrass biomass was generally the lowest with the highest rate of glyphosate applied at the earlier stages. Overall, no single application timing at any glyphosate rate provided complete control or biomass reduction of the annual ryegrass cover crop. A sequential herbicide program or a glyphosate plus a graminicide tank-mix probably will be needed for adequate annual ryegrass stand removal. Nomenclature: Glyphosate; annual ryegrass Lolium multiflorum L. LOLMU; corn, Zea mays L.; soybean, Glycine max (L.) Merr.

Wheat response to N2 fixed by faba bean (Vicia faba L.) as affected by sulfur fertilization and rhizobial inoculation in semi‐arid Northern Ethiopia

AbstractNitrogen fixation in faba bean (Vicia faba cv. Mesay) as affected by sulfur (S) fertilization (30 kg S ha–1) and inoculation under the semi‐arid conditions of Ethiopia was studied using the 15N‐isotope dilution method. The effect of faba bean–fixed nitrogen (N) on yield of the subsequent wheat crop (Triticum aestivum L.) was also assessed. Sulfur fertilization and inoculation significantly (p < 0.05) affected nodulation at late flowering stage for both 2004 and 2005 cropping seasons. The nodule number and nodule fresh weighs were increased by 53% and 95%, relative to the control. Similarly, both treatments (S fertilization and inoculants) significantly improved biomass and grain yield of faba bean on average by 2.2 and 1.2 Mg ha–1. This corresponds to 37% and 50% increases, respectively, relative to the control. Total N and S uptake of grains was significantly higher by 59.6 and 3.3 kg ha–1, which are 76% and 66% increases, respectively. Sulfur and inoculation enhanced the percentage of N derived from the atmosphere in the whole plant of faba bean from 51% to 73%. This corresponds to N2 fixation varying from 49 to 147 kg N ha–1. The percentage of N derived from fertilizer (%Ndff) and soil (%Ndfs) of faba bean varied from 4.3% to 2.8 %, and from 45.1% to 24.0%, corresponding to the average values of 5.1 and 47.9 kg N ha–1. Similarly, the %Ndff and %Ndfs of the reference crop, barley, varied from 8.5 % to 10.8% and from 91.5% to 89.2%, with average N yields of 9.2 and 84.3 kg N ha–1. Soil N balance after faba bean ranged from 13 to 52 kg N ha–1. Beneficial effects of faba bean on yield of a wheat crop grown after faba bean were highly significant, increasing the average grain and N yields of this crop by 1.11 Mg ha–1 and 30 kg ha–1, relative to the yield of wheat grown after the reference crop, barley. Thus, it can be concluded that faba bean can be grown as an alternative crop to fallow, benefiting farmers economically and increasing the soil fertility.

Evaluation of Potassium Compared to Other Osmolytes in Relation to Osmotic Adjustment and Drought Tolerance of Chickpea Under Water Deficit Environments

ABSTRACT Line source sprinkling irrigation system was used to evaluate potassium (K) and other major osmolytes (sugars, proline, total amino nitrogen, and potassium) in respect with differential yielding capabilities of two groups of chickpea varieties (BR group with brown-red seed and PY group with pale yellow seed) under water deficit. Leaf water relation parameters, osmolytes, and total osmotic potential at full turgor (Ψπ 100) were studied at early flowering (EF), late flowering (LF), and early fruiting (Eft) stages. Of the osmolytes, K accumulated in the highest amount (35 to 55% of the total Ψπ 100) in chickpea leaves regardless of growth stages and varietal groups. Varietal groups showed substantial accumulation of SPN (sugars + proline + amino nitrogen) and K with the increase in soil moisture stress irrespective of growth stages, the BR group proving to be a better accumulator of the osmolytes than PY group in most cases. However, the contribution of SPN to total Ψπ 100 increased, while that of K decreased generally with increasing soil moisture stress, particularly at Eft stage. The OA capacity of BR varieties increased, while that of PY varieties decreased significantly at EF and LF stages along the line source moisture gradient. However, potassium-contribution to OA decreased largely with the increase in water deficit and crop age. In fact, it contributed negligibly to OA at the Eft stage in case of both the varietal groups. Osmotic parameters, namely, total OA and Ψπ 100 as well as Ψπ 100 due to SPN and K, correlated linearly (P ≤ 0.05 or P ≤ 0.01) with seed yield, relative water content, and drought tolerance efficiency under water deficit, indicating their significant role in drought tolerance of the crop. Since BR varieties proved generally superior to PY varieties regarding all the osmotic parameters, the superior yielding capability of BR to PY varieties (26–30% yield benefit under water deficit), could be ascribed to the favorable effect of osmotic parameters on the sustenance of crop yield under water deficit. Thus, chickpea varieties could be selected for improved drought tolerance on the basis of total OA, Ψπ 100 and Ψπ 100, due to osmolytes. Moreover, the Ψπ 100, due to K, could prove as a good selecting tool; however, further research is required to know if the chickpea varieties with high efficiency of K accumulation across the growth stages are able to withstand water deficit more efficiently.

Foliar application of lipo-chitooligosaccharides (Nod factors) to tomato (Lycopersicon esculentum) enhances flowering and fruit production

Lipochitooligosaccharides (LCO) or Nod factors, which are rhizobia-produced signal molecules, induce deformation of legume root hairs. In addition to triggering legume plant nodulation, Nod factors influence cell division and promote somatic embryo generation in non-legume plants. This suggested to us the potential of using LCO to stimulate the development of tomato flowers and fruit. This study indicated that the foliar application o f LCO to tomato plants during the appropriate stages increased flower numbers and early fruiting in greenhouse trials. Flower stimulation by LCO occurred 1-2 wk after application and fruit numbers increased 2-4 wk after application. The accelerated flowering and fruiting resulted in an increase in tomato fruit yield. The most effective concentration of LCO was 50 ng per plant applied twice in the greenhouse, initially during the early flowering stage and again in the late flowering stage. A field trial in 2002 indicated that the optimal LCO application concentration was 10 ng per plant applied at the early flowering stage, which increased fruit yield and number by up to 29.8 and 29.4%, respectively. When plants received a second LCO application at the early fruiting stage, the fruit yield increased, but most were unmarketable green fruits. Analyses of yield data showed that the yield increase in field-grown tomatoes was due to an increase in the fruit number per plant, but not to individual fruit weight or fruit size. The average weight per fruit due to the treatment was not different from the control. A second field trial, carried out in 2003, showed that a foliar application of LCO at 50 ng per plant produced the best tomato yield. Our studies indicate that an LCO foliar application to tomatoes in the range of 10-50 ng per plant can increase early flowering and fruiting, which results in improved fruit yield. Key words: early flowering, foliar application, fruiting, growth promotion, lipo-chitooligosccharides, tomato yield

Mapping Ridolfia segetum patches in sunflower crop using remote sensing

Summary Ridolfia segetum is a frequent umbelliferous weed in sunflower crops in the Mediterranean basin. Field and remote sensing research was conducted in 2003 and 2004 over two naturally infested fields to determine the potential of multispectral imagery for discrimination and mapping of R. segetum patches in sunflower crops. The efficiency of the four wavebands blue (B), green (G), red (R) and near‐infrared (NIR), selected vegetation indices and the spectral angle mapper (SAM) classification method were studied using aerial photographs taken in the late vegetative (mid‐May), flowering (mid‐June) and senescence (mid‐July) crop growth stages. Discrimination efficiency of R. segetum patches in sunflower crops is consistently affected by their phenological stages, in this order: flowering > senescence > vegetative. In both fields, R. segetum patches were efficiently discriminated in mid‐June, corresponding to the flowering phase, by using the waveband G, the ratio R/B or SAM with overall accuracies ranging from 85% to 98%. The application of the median‐filtering algorithm to any of the classified images improved the accuracy. Our results suggest that mapping R. segetum weed patches in sunflower to implement site‐specific weed management techniques is feasible with aerial photography when images are taken from 8 to 10 weeks before harvesting.

Genetic variability of principal isoflavones in red clover

Isoflavones, known for their health benefits, are abundant in red clover (Trifolium pratense L.). Total isoflavone concentrations can be 30 times that of soybean, indicating that red clover is a good source of nutraceutical and functional food ingredients. In this study, tissue samples of 13 red clover cultivars were taken at two growth stages (late-bud stage and late-flowering stage) to determine the concentration of individual isoflavones using HPLC. Individual isoflavone concentrations and total isoflavone concentration differed significantly according to red clover cultivar. We found significant genetic variability for total isoflavone concentration and individual isoflavone concentrations; these differences were not related to ploidy level (diploid vs. tetraploid). Broad-sense heritability (H = genetic variance/total variance) ranged from 0 to 83% and was influenced by isoflavone type and sampling date. The results of this study suggest that there is significant genetic variability for isoflavone concentrations among currently available red clover cultivars. Key words: Trifolium pratense L., biochanin A, formononetin, growing stages, broad-sense heritability

The spatio-temporal distribution dynamics of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Coleoptera: Curculionidae), and its larval parasitoids in canola in western Canada

Distribution patterns of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae), and its larval parasitoids were investigated in commercial fields of spring canola (Brassica rapa L. and Brassica napus L.) in southern Alberta, Canada, from 2002 to 2004 in relation to developmental stages of its host plants. Adult weevils invaded fields along one or more fronts when crops were in bud to early flower. Significant clustering of adults along field edges in early stages of invasion was followed by more homogeneous distributions as canola reached the mid to late flowering and pod enlargement stages. Larval weevil distributions, as indicated by exit holes in siliques at the end of the season, were often aligned spatially with adult distributions, but they did not coincide in all regions of the fields. The primary ectoparasitoid species attacking weevil larvae comprised Necremnus tidius (Walker) (Hymenoptera: Eulophidae), and Trichomalus lucidus (Walker), Chlorocytus sp., and Pteromalus sp. (Hymenoptera: Pteromalidae). Parasitism rates increased from 0.1 to 5.0% over the three years of study. Parasitoid distributions were often, but not consistently, spatially associated with high densities of C. obstrictus larvae. Lack of close spatial alignment of parasitoids and their hosts probably reflects low parasitoid numbers in comparison with an abundant resource of weevil larvae, and a lack of co-evolutionary history between host and parasitoids. Some parasitoids invaded fields early in host plant development, at the same time that weevils invaded. Unfortunately the synchronous invasions of host and parasitoids indicate that insecticidal applications to reduce adult weevil infestations may be detrimental to these beneficial species.

<I>In vitro</I> degradability and gas production parameters of Sericea lespedeza (<I>Lespedeza cuneata</I>) mixed with varying types and levels of roughages

Sericea lespedeza (Lespedeza cuneata) regrowth was harvested at early (ELP) or late (LLP) flowering stages, mixed with varying types and levels of roughage and fermented for 72 h in vitro, using the gas production (GP) technique. The roughage : lespedeza ratios were 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. The roughages included maize stover harvested at grain milk (MM) or dry (MD) stages and veld grass hay (GH). The crude protein (CP) content of ELP, LLP, MM, MD and GH were 187, 97, 48, 29 and 34 g/kg dry matter (DM), respectively. The corresponding NDF values were 283, 589, 696, 73.3 and 665 g/kg DM. Degradability was slightly higher in MM as compared to MD and GH (means 704.9 vs. 676.6 and 685.0 g/kg, respectively) between ELP rations. The roughages had similar but lower degradability in LLP rations (means 633.4, 632.6 and 631.1 g/kg for MM, MD and GH, respectively). Increased proportion of ELP and LLP resulted in decreased degradability in all the roughages. Microbial yield was similar among roughages in ELP rations, but the roughages differed in microbial yield among LLP rations whereby GH had the highest value and MD the lowest. Increased proportion of ELP elicited an increase in microbial yield but increasing LLP had no effect (range 135.0 – 264.8 g/kg among ELP and 143.4 – 295. 9 g/kg among LLP rations). Roughage type affected GP with MD and GH having the lowest and highest values, respectively. The values ranged from 167.4 – 209.8 and 160.4 – 221.0 mL among ELP and LLP rations, respectively. There was a decrease in GP as the proportion of ELP or LLP increased and roughage type x supplement level interaction had effect. The ratio of degradability to GP, i.e. the partitioning factor (PF) ranged from 3.43 – 4.74 and 3.13 – 4.23 among ELP and LLP rations, respectively, whereby GH had highest and MD lowest values. The rate of GP from soluble fraction was not affected, but that of the fibre fraction differed among the roughages in ELP rations whereby GH had lower rate than MM and MD (mean 0.023 vs. 0.026 and 0.025, respectively). The lag time (lt) tended to be reduced as ratio of ELP increased (range 1.83 to 6.59 h). In LLP rations, roughage type, supplementation level, roughage type x supplementation level interactions affected lt. The GH had the longest and MM had the shortest lt among the roughages (range 0.88 – 9.61 h), and likewise lt reduced as ratio of LLP increased. The results indicate that the various nutritive attributes considered are differentially influenced by lespedeza type and level, roughage type and the interactions among these aspects, hence the importance of their implications in formulating ruminant diets. The results indicate that when using roughages with similar quality as those studied, lespedeza ratio of 40 - 60% of DM consumed can be beneficial. South African Journal of Animal Science Vol. 36(2) 2006: 111-121

Wheat Responses in Semiarid Northern Ethiopia to N2 Fixation by Pisum Sativum Treated with Phosphorous Fertilizers and Inoculant

Nitrogen fixation (N2) by leguminous crops is a relatively low-cost alternative to N fertilizers for smallholder farmers in Africa. Nitrogen fixation in pea (Pisum sativum L. cv. Markos) as affected by phosphorus (P) fertilization (0, 30 kg P ha−1) and inoculation (uninoculated and inoculated) in the semiarid conditions of Northern Ethiopia was studied using the 15N isotope dilution method and locally adapted barley (Hordeum vulgare L. cv. Bureguda) as reference crop. The effect of pea fixed nitrogen (N2) on yield of the subsequent wheat crop (Triticum aestivum L.) was also assessed. Phosphorus and inoculation significantly influenced nodulation at the late flowering stage and also significantly increased P and N concentrations in shoots, and P concentration in roots, while P and N concentrations in nodules were not affected. Biomass, pods m−2 and grain yield responded positively to P and inoculation, while seeds pod−1 and seed weights were not significantly affected by these treatments. Phosphorus and inoculation enhanced the percentage of N derived from the atmosphere in the whole plant ranging from 53 to 70%, corresponding to the total amount of N2 fixed varying from 55 to 141 kg N ha−1. Soil N balance after pea ranged from − 9.2 to 19.3 kg N ha−1 relative to following barley, where barley extracted N on the average of 6.9 and 62.0 kg N ha−1 derived from fertilizer and soil, respectively. Beneficial effects of pea fixed N2 on yield of the following cereal crop were obtained, increasing the average grain and N yields of this crop by 1.06 Mg ha−1 and 33 kg ha−1, respectively, relative to the barley–wheat monocrop rotation. It can be concluded that pea can be grown as an alternative crop to fallow, benefiting farmers economically and increasing the soil fertility.

Isoflavone Profiles of Red Clovers and Their Distribution in Different Parts Harvested at Different Growing Stages

The isoflavone compositions and concentrations in the leaf, flower, petiole, and stem of 13 red clover cultivars were studied using high-performance liquid chromatography coupled with a diode array and a mass spectrometric detector with negative electrospray ionization. Different cultivars showed significantly different concentrations of individual and total isoflavones. The leaf contained the highest overall concentration, followed by the stem, petiole, and flower. Biochanin A and formononetin were the predominant isoflavones in all cultivars and all parts, along with eight other minor aglycones, daidzein, genistein, glycitein, irilone, orobol, pratensein, pseudobaptigenin, and prunetin, and four minor malonylglycosides, genistein-7-glucoside-6' '-malonate, orobol-7-glucoside-6' '-malonate, formononetin-7-glucoside-6' '-malonate, and biochanin A-7-glucoside-6' '-malonate. The isoflavone compositions and concentrations were also found to be different between red clover parts harvested at the early bud stage and the late flowering stage. Sample storage and handling prior to analysis were also found to be important. Samples in this study were kept at -5 degrees C for a few days before being freeze-dried and were found to contain mainly the aglycones of isoflavones. This may actually be an advantage in that "natural" and more bioactive isoflavones can be obtained without using chemical hydrolysis. Findings in this study therefore provide important information for developing isoflavone-rich red clovers and for optimizing harvest timing and choosing the right part of the red clover plant.

Hyperspectral Characteristics of Canopy Components and Structure for Phenological Assessment of an Invasive Weed

Spectral reflectance values of four canopy components (stems, buds, opening flowers, and postflowers of yellow starthistle (Centaurea solstitialis)) were measured to describe their spectral characteristics. We then physically combined these canopy components to simulate the flowering stage indicated by accumulated flower ratios (AFR) 10%, 40%, 70%, and 90%, respectively. Spectral dissimilarity and spectral angles were calculated to quantitatively identify spectral differences among canopy components and characteristic patterns of these flowering stages. This study demonstrated the ability of hyperspectral data to characterize canopy components, and identify different flowering stages. Stems had a typical spectral profile of green vegetation, which produced a spectral dissimilarity with three reproduction organs (buds, opening flowers, and postflowers). Quantitative differences between simulated flower stages depended on spectral regions and phenological stages examined. Using full-range canopy spectra, the initial flowering stage could be separated from the early peak, peak, and late flowering stages by three spectral regions, i.e. the blue absorption (around 480 nm) and red absorption (around 650 nm) regions and NIR plateau from 730 nm to 950 nm. For airborne CASI data, only the red absorption region and NIR plateau could be used to identify the flowering stages in the field. This study also revealed that the peak flowering stage was more easily recognized than any of the other three stages.

Wrinkled petals and stamens 1, is required for the morphogenesis of petals and stamens in Lotus japonicus

Although much progress has been made in understanding how floral organ identity is determined during the floral development, less is known about how floral organ is elaborated in the late floral developmental stages. Here we describe a novel floral mutant, wrinkled petals and stamens1 (wps1), which shows defects in the development of petals and stamens. Genetic analysis indicates that wps1 mutant is corresponding to a single recessive locus at the long arm of chromosome 3. The early development of floral organs in wps1 mutant is similar to that in wild type, and the malfunction of the mutant commences in late developmental stages, displaying a defect on the appearance of petals and stamens. In the mature flower, petals and stamen filaments in the mutant are wrinkled or folded, and the cellular morphology under L1 layer of petals and stamen filaments is abnormal. It is found that the expression patterns of floral organ identity genes are not affected in wps1 mutants compared with that of wild type, consistent with the unaltered development of all floral organs. Furthermore, the identities of epidermal cells in different type of petals are maintained. The histological analysis shows that in wps1 flowers all petals are irregularly folded, and there are knotted structures in the petals, while the shape and arrangement of inner cells are malformed and unorganized. Based on these results, we propose that Wps1 acts downstream to the class B floral organ identity genes, and functions to modulate the cellular differentiation during the late flower developmental stages.

The effect of MCPA and paclobutrazol on flowering, berry set, biomass production, tuber yield and quality of potato

The effects of MCPA and paclobutrazol on potato (Solanum tuberosum L.) flowering, berry formation, dry matter production and allocation, tuber yield and quality were investigated under greenhouse and field conditions at the Experimental Farm of the University of Pretoria. Both MCPA and paclobutrazol were applied during early and full bud stage at rates of 0, 5.6,11.2, and 16.9 mg a.i. plant−1. Regardless of rates and stages of application MCPA and paclobutrazol prevented flowering and completely inhibited berry set. MCPA did not affect the number, yield, specific gravity and dry matter content of the tubers. Without affecting the number of tubers initiated, paclobutrazol increased tuber yield, specific gravity and dry matter content. MCPA decreased assimilate partitioning to the stems. Paclobutrazol treatment at early flower bud stage resulted in higher tuber yield than spraying during late flower bud stage. Paclobutrazol decreased assimilate partitioning to the leaves, stems, and roots while it increased partitioning to the tubers. A single foliar spray of MCPA or paclobutrazol at the early flower bud stage at a rate of 250g a.i. ha−1 reduced flower formation and completely inhibited berry set.

Determination of nutritive value of leaves of a native grown shrub, Glycyrrhiza glabra L. using in vitro and in situ measurements

In this study, the nutritive values of the leaves of Glycyrrhiza glabra L., a native grown shrub, hand harvested from three plots established in the experimental field at prebud, mid and late flower stages were evaluated in terms of the chemical composition, in vitro gas production, and in situ dry matter (DM) and crude protein (CP) degradation. Gas production, DM and CP disappearance were determined at 0, 3, 6, 12, 24, 48, 72 and 96 h and their kinetics were described using the equation y = a + b(1 − e − ct ). Maturity had a significant effect on the chemical composition, gas production, metabolizable energy (ME), DM and CP degradability of the leaves of G. glabra L. Neutral detergent fiber (NDF), acid detergent fiber (ADF) and condensed tannin (CT) contents increased with increasing maturity whereas the crude protein decreased. Gas production, DM, CP disappearance and estimated parameters also decreased with increasing maturity. CP, ADF and CT contents ranged from 16.19 to 26.93%, from 20.74 to 29.07% and from 1.57 to 10.83%, respectively. The potential gas production and ME ranged from 65.34 to 72.12 ml/0.200 g of DM and from 10.14 to 12.12 MJ/kg DM, respectively. The effective DM degradability (EDMD) and effective CP degradability (ECPD) ranged from 58.70 to 70.59% and from 57.32 to 73.72%. Gas production, DM and CP disappearance, and estimated parameters of the leaves of G. glabra L. harvested at prebud stage were significantly higher than those harvested at mid and late flower stages. Gas production, DM and CP disappearance, and estimated parameters were negatively correlated with NDF, ADF and CT, whereas they are positively correlated with CP. G. glabra L. harvested at the proper stage of maturity offers considerable potential as a high quality forage for ruminant during critical period in the semi arid and arid regions.

Seed size as an indicator of seed quality: a case study of Primula veris

Seed size is a widely accepted measure of seed quality, because many earlier studies have shown that large seeds have high seedling survival, growth and establishment. We tested whether ovule loss increases size of the remaining seeds and whether such size increase affects seedling establishment. We removed all except one flower from inflorescences of Primula veris L. (Primulaceae), a perennial hemicryptophyte herb, at a late stage of flowering. Flower removal (FR) increased seed size by 33% compared to the control plants. We then divided the seeds within each treatment to small, middle-sized and large seeds and carried out a sowing experiment in the field. Within each experimental group, seedling establishment was positively associated with seed size. However, despite size differences, seeds from the FR and control groups had the same seedling establishment probability. Seeds from FR plants had a higher seedling emergence in May than those from control plants, but the number of seedlings alive per sowing plot in the late summer was the same in both experimental groups. Increase in seed mass after partial FR thus did not enhance seedling performance, although seed size variation due to other causes was positively correlated with seedling establishment. Further studies are needed to show whether plastic changes of seed size are usually adaptive or not.

Activity of microorganisms in the rhizosphere of herbicide treated and untreated transgenic glufosinate-tolerant and wildtype oilseed rape grown in containment

An experiment was carried out with plants grown in containment in order to determine potential effects on metabolically active microbial populations as well as on soil enzyme activities in the rhizosphere of genetically modified Basta-tolerant oilseed rape. Transgenic as well as isogenic wild-type plants were grown in combination with the associated herbicide Basta (active ingredient glufosinate) or the herbicide Butisan S (active ingredient metazachlor), respectively. In control treatments, weeds were mechanically removed. Rhizosphere soil was sampled at the early and late flowering stage as well as at senescence. RNA was isolated and 16S rRNA was amplified by reverse transcription and PCR. Amplicons were subjected to denaturating gradient gel electrophoresis in order to generate community fingerprints of metabolically highly active bacteria. Additionally, RNA was hybridized with group-specific probes. Furthermore, bacterial biomass and activities of invertase, alkaline phosphatase, urease and arylsulfatase were determined. Results showed that oilseed rape rhizosphere bacteria were affected by the genetic modification as well as by the herbicide application, however, these effects were minor compared to the influence of the plant growth stage. At senescence, invertase, urease and alkaline phosphatase activities were significantly enhanced in the rhizospheres of transgenic plants as compared to wild-type plants propably due to an altered root exudation in comparison to the wildtype plant. Dot blot hybridizations indicated altered activities and/or abundances of various phylogenetic groups at all sampling times. The transformation process may have unintentionally altered the physiology of plants (e.g. root exudation) leading to changes in rhizosphere community structures and bacterial activities.

Effect of foliar fungicide application timing on the control of bean anthracnose in the navy bean ‘Navigator’

Bean anthracnose, caused by Colletotrichum lindemuthianum, can severely reduce bean yield and seed quality. A 2-year field study at two sites in southern Manitoba examined the effect of the timing of foliar applications of the fungicide pyraclostrobin (Headline® 250 EC) on the control of bean anthracnose in navy bean (Phaseolus vulgaris) ‘Navigator’. Single and (or) sequential applications of pyraclostrobin at a rate of 0.1 kg active ingredient (a.i.)/ha were made at four growth stages. Single applications of pyraclostrobin, at either 3 to 5 trifoliolate leave stage, early flowering (40% bloom), late flowering (80% bloom), or 10 days after flowering, reduced disease development in the crop canopy, but had inconsistent effects on pod infection, seed discoloration, and yield. Sequential applications of pyraclostrobin at the early and late flowering stages usually resulted in the lowest disease severity on all parts of the plant and in the highest yield. Sequential applications of pyraclostrobin at the late flowering stage and 10 days after flowering were less effective in reducing anthracnose severity and seed discoloration than the earlier sequentialapplication treatment. Both sequential-application treatments of pyraclostrobin had similar yields. Under Manitoba growing conditions, seed-borne infection by C. lindemuthianum resulted in yield reductions that ranged from 15.2% to 32.1% in the untreated bean plots.