Effects Of Sampling Date Research Articles

Establishing rhizoma peanut–bahiagrass mixtures

AbstractRhizoma peanut (RP;Arachis glabrataBenth.) is a perennial legume with ability to persist and spread in mixtures with C4grasses. Most RP establishment studies focus on its use as a monoculture hay crop, and more information is needed on establishment strategies for RP–grass mixtures. The objectives of this study were to compare techniques for establishing RP–grass mixtures and quantify their effects on RP shoot emergence, frequency of occurrence (percentage of quadrats containing RP shoots), percentage ground cover, and RP shoot and root‐rhizome biomass. Treatments were (a) RP planted in monoculture (MRP; control), (b) RP planted simultaneously with bahiagrass (Paspalum notatumFlügge; RP‐BG), or (c) RP strip planted into existing bahiagrass pasture following removal of bahiagrass sod strips (Strip). There was no treatment or sampling date effect on RP shoot density (29.5 shoots m–2) during 10 wk after spring planting. By October, RP ground cover was greater for Strip (43%) than MRP (32%) and for MRP than RP‐BG (18%), and Strip and MRP had greater RP frequency than RP‐BG (82, 72, and 58%, respectively). Strip and MRP (1.39 and 1.10 Mg ha–1, respectively) had greater year‐of‐planting RP shoot mass than RP‐BG (0.52 Mg ha–1), but root‐rhizome biomass was not affected by treatment. Measures of establishment success for Strip generally were equal or superior to MRP, and Strip is a viable option for establishing RP–grass mixtures. Weed competition reduced RP establishment success in RP‐BG relative to the other treatments because herbicides tolerated by both bahiagrass seedlings and emerging RP shoots are unavailable.

Monitoring soil organic matter on grassland farms: An exploratory analysis

To meet the goals of the Climate Agreement, policy makers consider incentivizing soil carbon sequestration by carbon credits to offset greenhouse gas emissions from agriculture, industry and other sectors. Therefore, the interest in monitoring soil organic matter dynamics is growing rapidly, yet factors affecting the precision of the monitoring results are rarely quantified. We used the rhetorical scheme “The seven circumstances” to structure the methodological aspects of setting up a soil organic matter (SOM) monitoring program. The rhetorical scheme was applied during four years on two grass-based dairy farms in the Netherlands to assess in detail: conversion of SOM weight concentrations to SOM stocks (HOW), the effect of soil depth and the integration of scales field vs. farm (WHERE), and the effect of sampling date and sampling frequency on SOM estimates (WHEN). We found that all three circumstances affect conclusions on SOM stocks or SOM dynamics strongly. Considerable variation was found in the relationship between soil bulk density and SOM weight concentration (i.e. pedotransfer curves) among fields, depth and literature reference equations. Therefore, preferably a site specific pedotransfer curve should be used when comparing SOM stocks based on SOM weight concentrations across sites. Large differences in trends of SOM stock changes over time were found between fields and sampling depths. We conclude that a sampling depth in grassland soils up to 60 cm may be relevant to capture the dynamics in deeper layers. Furthermore, for quantitative underpinning of carbon payment schemes, the whole farm should be monitored rather than a few fields as trends between fields are highly variable.

The synchrony of cover crop decomposition, enzyme activity, and nitrogen availability in a corn agroecosystem in the Midwest United States

Cover cropping is commonly associated with increased soil microbial activity and soil health. Cover cropping in the Upper Mississippi River Basin has increased rapidly in the last decade due to the demonstrated ability that cover crops can increase soil health and decrease nitrate losses in tile-drained fields. One reason cover cropping is not adopted in the Midwest United States is the lack of knowledge on the synchrony of cover crop residue nitrogen (N) release and corn N demand. Therefore, the overarching goal of this research was to investigate soil enzyme activity and inorganic N availability during the decomposition period of common winter cover crops. Objectives were: i) to determine if soil enzyme activity (β-glucosidase and urease) is influenced by different cover crops (cereal rye (CR), hairy vetch (HV), and HV/CR mixture) and tillage systems (reduced tillage and no-tillage residue management) during the residue decomposition period, and ii) to determine the relationship between soil enzyme activity, inorganic N availability, and critical corn growth stages during cover crop decomposition. Cover crops in this study were selected due to contrast in residue carbon (C):N ratios, their commonality among regional farmers, and their differences in physiology. Spring tillage and no-tillage were investigated because of the differing levels of soil disturbance and residue incorporation. Enzyme activities were quantified at seven sampling dates following cover crop termination from April-October during the 2016 and 2017 corn growing seasons. Results revealed significant effects of sampling date (p < 0.001) and cover crop treatment (p < 0.05) on soil β-glucosidase activity and significant interaction effects between sampling date and cover crop treatment (p < 0.05) on potential soil urease activity. Tillage had a significant impact on soil β-glucosidase (p < 0.001) and urease (p < 0.05) activities in 2017, with higher activity observed in the no-tillage soil. These findings indicate that enzyme activity fluxes can be observed in agroecosystems one year after introducing conservation practices, such as cover crops and no-tillage. Greater than 50 % of C release from cover crop residue occurred from corn emergence to tasseling, and significantly greater β-glucosidase activity for CR-based treatments during corn peak N demand did not result in more soil inorganic N. This indicates a loss of plant-available N from the agroecosystem, which could be attributed to N immobilization by the soil microbial community. This study demonstrates a need to develop adaptive N fertilization management for corn that can overcome the potential impact of N immobilization during peak corn N demand following CR.

Seasonal abundance and development of the Asian longhorned beetle and natural enemy prevalence in different forest types in China

Seasonal abundance and population development of the Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), and prevalence of its natural enemies were studied on Hankow willow (Salix matsudana Koidz.) at an urban forest site (Anci) and a rural forest site (Tangerli) in Hebei province in northern China from June to October, 2002. Overall, ALB abundance was significantly lower in the urban forest in Anci than in the rural forest in Tangerli. Population density ranged from 0 to 1.0 pupae/branch, 0.1 to 0.7 adults/tree, 0.1 to 9.2 eggs/branch, and 5.9 to 18.4 larvae/branch at Anci, and 0.1 to 0.9 pupae/branch, 0.1 to 1.6 adults/tree, 0 to 22.9 eggs/branch, and 5.0 to 34.1 larvae/branch at Tangerli, respectively. A significant effect of sampling date was observed for all ALB life stages. Significantly fewer 3rd and 4th size class larvae were found in the urban forest at Anci compared to the rural forest at Tangerli. Prevalence of the gregarious larval-pupal ectoparasitoid Dastarcus helophoroides (Fairmaire) (= D. longulus) (Coleoptera: Bothrideridae) did not differ between Anci and Tangerli, but percent parasitism differed among sampling dates and peaked in June at 32.8±7.4% at Anci and 12.0±3.5% at Tangerli. Parasitism was lowest in August in Tangerli and September in Anci when most ALB larvae were at an early stage of development. The mean D. helophoroides clutch size was 5.67±0.37 parasitoids per ALB larva or pupa and did not differ between the two sites or among sample dates. Similar ALB population densities and D. helophoroides parasitism were also found at two supplemental study sites in Tianjin city (Yangcun and Xiaoxitian) where samples were only taken in June 2002. A localized epizootic of B. bassiana was observed on immature stages of ALB at Tangerli in July, resulting in an average infection rate of 2.4%. Differences in ALB population development and natural enemy prevalence between urban and rural forest site, and the potential of D. helophoroides and other natural enemies in the management of A. glabripennis are discussed.

Use of response surface methodology for the assessment of changes in the volatile composition of Moscato bianco (Vitis vinifera L.) grape berries during ripening

The changes in the volatile composition of Moscato bianco grapes were evaluated during ripening. Grape berries were sampled for five weeks (16–20 °Brix) and sorted for each date in ten density classes (1.05–1.12g/cm3). The highest total concentration of free terpenes was found at 19.3 °Brix; however, total concentration of the bound fraction increased significantly throughout ripening. Response surface methodology was used to assess the simultaneous effect of sampling time and berry density on the volatile composition, which was satisfactorily fitted to regression models for some key terpene compounds. Total free and bound terpenes were more affected by grape density than by sampling date. The same behaviour was observed for free and bound linalool and bound nerol, whereas the stronger effect of sampling date was exhibited for bound t-rose oxide, c-rose oxide and geraniol. The results showed that the sampling strategy impacted strongly on the aroma quality of berries.

Effect of Dietary Supplementation of Spirulina (Arthrospira Platensis) and Thyme (Thymus Vulgaris) on Serum Biochemistry, Immune Response and Antioxidant Status of Rabbits

Abstract Growing rabbits’ (42 rabbits/group, 3 rabbits/cage, 14 cages/treatment) diet was supplemented with 5% Spirulina (Arthrospira platensis) and 3% thyme (Thymus vulgaris L.) powder single (S or T) and in combination (ST) between 35 and 77 days of age. On day 0 (weaning at 35 days of age) 14 rabbits were vaccinated with 100 μg/animal ovalbumin to provoke immune response. Blood samples were taken on days 0, 14, 28 and 42 of the experimental period. Sampling dates significantly influenced total protein, albumin, glucose, cholesterol, urea, creatinine concentration and enzyme (AST, ALT, GGT) activities, with a significant age × diet interaction in the case of TP and CREA. There was a significant increase in ALT (+45 and 74%) and GGT (+87 and 102%) activity after immunisation. While Spirulina and thyme significantly ameliorated the rise in AST activity, their effect was inefficient in the case of GGT. Spirulina, both single and in combination showed a tendency in higher IgG level as compared to control (P&lt;0.05). No significant effect of sampling date or treatment on phagocytic activity or secretory IgA was demonstrable (P&gt;0.05). Higher MDA concentration was measured in the red blood cells of S, T and ST animals, while no other significant diet effect on the antioxidant parameters was detected, however, significant sampling date × diet interaction was found in the case of GPx activity. Plasma GGT (increase by 19-66%) was inversely associated with GSH (decrease by 66-113%) between days 0 to 42 of the experimental period (r=-0.57, P&lt;0.05). It can be concluded that Spirulina supplementation alone resulted in higher IgG production, but none of the phytobiotics, at the dose used, affected significantly the antioxidant status of blood.

Tillage, seasonal and depths effects on soil microbial properties in black soil of Northeast China

Tillage practice can alter the content and distribution of soil organic matter by burying crop residue and soil disturbance, which would impact soil microbial properties. The objective of the present study was to evaluate the effects of tillage practices (no tillage, NT; ridge tillage, RT; mouldboard plow, MP) and sampling date (April, June, September) on soil microbial properties at different soil depths. Soil core samples were taken at 0–5, 5–10 and 10–20cm depths from a long-term tillage experiment site (initiated in 2001) in black soils in northeast China. Microbial biomass and extractable organic C were determined using by chloroform-fumigation-extraction method. Microbial abundance and community structure were determined using the phospholipid fatty acid (PLFA) method. Principal response curve (PRC) analysis revealed the magnitude of the effect of sampling date on the PLFA relative abundance decreased with depth within the tilled layer, whereas increased with depth for tillage practice. Microbial biomass carbon, abundance and the F/B ratio varied with the variation in available substrates at the 0–5cm depths. NT and RT improved microbial abundance (total, fungal and bacterial abundance) in the 0–5cm depth soil, but they did not contribute to a higher F/B ratio in the 0–5cm depth soil, and had a lower F/B ratio than MP in the deeper soils below 5cm depth. These results demonstrated that long-term conservation tillage practice has potential for improving microbial properties in surface soil, but may not cause a shift of microbial community structure in Northeast China.

Effects of cultivar and grazing initiation date on fall-grown oat for replacement dairy heifers

Fall-grown oat has shown promise for extending the grazing season in Wisconsin, but the optimum date for initiating grazing has not been evaluated. Our objectives for this project were (1) to assess the pasture productivity and nutritive value of 2 oat cultivars [Ogle and ForagePlus (OG and FP, respectively)] with late-September (EG) or mid-October (LG) grazing initiation dates; and (2) to evaluate growth performance by heifers grazing these oat forages compared with heifers reared in confinement (CON). A total of 160 gravid Holstein heifers (80 heifers/yr) were assigned to 10 research groups (8 heifers/group). Mean initial body weight was 509±40.5 kg in 2013 and 517±30.2 kg in 2014. Heifer groups were assigned to specific pastures arranged as a 2×2 factorial of oat cultivars and grazing initiation dates. Grazing heifer groups were allowed to strip-graze oat pastures for 6 h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Main effects of oat cultivar and sampling date interacted for forage characteristics in 2013, but not in 2014. During 2013, oat forage mass increased until early November before declining in response to freezing weather conditions, thereby exhibiting linear and quadratic effects of sampling date, regardless of oat cultivar. Similar trends over time were observed in 2014. For 2013, the maximum forage mass was 5,329 and 5,046 kg/ha for FP and OG, respectively, whereas the mean maximum forage mass for 2014 was 4,806 kg/ha. ForagePlus did not reach the boot stage of growth during either year of the trial; OG matured more rapidly, reaching the late-heading stage during 2013, but exhibited only minor maturity differences from FP in 2014. For 2013, average daily gain for CON did not differ from grazing heifer groups (overall mean=0.63 kg/d); however, average daily gain from FP was greater than OG (0.68 vs. 0.57 kg/d), and greater from EG compared with LG (0.82 vs. 0.43 kg/d). For 2013, advantages in average daily gain for heifers grazing FP pastures were likely related to the greater energy density of FP oat throughout the fall that reached a maximum of 68.8% total digestible nutrients on November 27 compared with only 63.7% for OG on October 10. During 2014, average daily gain from CON exceeded all grazing heifer groups (0.81 vs. 0.57 kg/d), and average daily gain from EG again exceeded LG (0.70 vs. 0.44 kg/d). These results suggest that delaying grazing until mid-October will consistently suppress heifer growth performance, particularly if rapidly maturing cultivars are used.

Seasonal influence of climate manipulation on microbial community structure and function in mountain soils

Microbial communities drive soil organic matter (SOM) decomposition through the production of a variety of extracellular enzymes. Climate change impact on soil microbial communities and soil enzymatic activities can therefore strongly affect SOM turnover, and thereby determine the fate of ecosystems and their role as carbon sinks or sources.To simulate projected impacts of climate change on Swiss Jura subalpine grassland soils, an altitudinal soil transplantation experiment was set up in October 2009. On the fourth year of this experiment, we measured microbial biomass (MB), microbial community structure (MCS), and soil extracellular enzymatic activities (EEA) of nine hydrolytic and oxidative extracellular enzymes in the transplanted soils on a seasonal basis.We found a strong sampling date effect and a smaller but significant effect of the climate manipulation (soil transplantation) on EEA. Overall EEA was higher in winter and spring but enzymes linked to N and P cycles showed higher potential activities in autumn, suggesting that other factors than soil microclimate controlled their pool size, such as substrate availability. The climate warming manipulation decreased EEA in most cases, with oxidative enzymes more concerned than hydrolytic enzymes. In contrast to EEA, soil MB was more affected by the climate manipulation than by the seasons. Transplanting soils to lower altitudes caused a significant decrease in soil MB, but did not affect soil MCS. Conversely, a clear shift in soil MCS was observed between winter and summer. Mass-specific soil EEA (EEA normalized by MB) showed a systematic seasonal trend, with a higher ratio in winter than in summer, suggesting that the seasonal shift in MCS is accompanied by a change in their activities. Surprisingly, we observed a significant decrease in soil organic carbon (SOC) concentration after four years of soil transplantation, as compared to the control site, which could not be linked to any microbial data.We conclude that medium term (four years) warming and decreased precipitation strongly affected MB and EEA but not MCS in subalpine grassland soils, and that those shifts cannot be readily linked to the dynamics of soil carbon concentration under climate change.

Seasonal variation of circulating plasma carotenoids in Mediterranean Great Tit males Parus major

Capsule Mediterranean Great Tits showed a marked increase in levels of circulating carotenoids during moult and autumn.Aims To study seasonal variation in plasma carotenoid content during a whole annual cycle for Great Tits Parus major inhabiting a Mediterranean woodland.Methods We used a sample of 71 adult male Great Tits captured in NE Spain during a whole year. Data were organized into four seasons (winter, breeding, moult and autumn). We sampled blood to extract plasma. Carotenoid plasma concentrations were analysed by High-performance liquid chromatography (HPLC).Results Lutein and zeaxanthin content varied seasonally, with a marked increase in levels during moult and autumn. Within the moulting period, levels increased gradually as the season progressed. This pattern differed significantly from that previously described in northern European populations, where high values appear mainly in the breeding season. Carotenoid concentrations (lutein: 1.2 ± 0.25, zeaxanthin: 0.07 ± 0.03 µg mL−1) were also lower than in northern Europe.Conclusion Mediterranean Great Tits show a very different pattern of circulating carotenoids and lower levels than northern European populations. The increasing pattern of carotenoid availability found within the moulting period raises the need to control for the effect of sampling date when analysing data on carotenoid concentrations at different times of year.

Diurnal pollen tube growth rate is slowed by high temperature in field-grown Gossypium hirsutum pistils

For Gossypium hirsutum pollination, germination, and pollen tube growth must occur in a highly concerted fashion on the day of flowering for fertilization to occur. Because reproductive success could be influenced by the photosynthetic activity of major source leaves, we hypothesized that increased temperatures under field conditions would limit fertilization by inhibiting diurnal pollen tube growth through the style and decreasing subtending leaf photosynthesis. To address this hypothesis, G. hirsutum seeds were sown on different dates to obtain flowers exposed to contrasting ambient temperatures while at the same developmental stage (node 8 above the cotyledons). Collection and measurement were conducted at 06:00, 09:00, 12:00, 15:00, and 18:00 h on August 4 (34.6 °C maximum air temperature) and 14, 2009 (29.9 °C maximum air temperature). Microclimate measurements included photosynthetically active radiation, relative humidity, and air temperature. Pistil measurements included pistil surface temperature, pollen germination, pollen tube growth through the style, fertilization efficiency, fertilized ovule number, and total number of ovules per ovary. Subtending leaf measurements included leaf temperature, photosynthesis, and stomatal conductance. Under high temperatures the first measurable pollen tube growth through the style was observed earlier in the day (12:00 h) than under cooler conditions (15:00 h). Also, high temperature resulted in slower pollen tube growth through the style (2.05 mm h −1) relative to cooler conditions (3.35 mm h −1), but there were no differences in fertilization efficiency, number of fertilized ovules, or ovule number. There was no effect of sampling date on diurnal photosynthetic patterns, where the maximum photosynthetic rate was observed at 12:00 h on both dates. It is concluded that, of the measured physiological and reproductive processes, pollen tube growth rate showed the greatest sensitivity to high temperature under field conditions.

Short-term dynamics of soil carbon, microbial biomass, and soil enzyme activities as compared to longer-term effects of tillage in irrigated row crops

Biol Fertil Soils (2009) 46:65–72 DOI 10.1007/s00374-009-0400-0 SHORT COMMUNICATION Short-term dynamics of soil carbon, microbial biomass, and soil enzyme activities as compared to longer-term effects of tillage in irrigated row crops Daniel Geisseler & William R. Horwath Received: 6 March 2009 / Revised: 1 May 2009 / Accepted: 5 May 2009 / Published online: 25 August 2009 # The Author(s) 2009. This article is published with open access at Springerlink.com Introduction The effects of disturbance on soil quality are difficult to determine because soil is inherently variable and physical and chemical soil properties change too slowly to reflect recent management history. Microbial and biochemical soil properties have been suggested as early and sensitive indicators of changes in soil quality as they manifest themselves over shorter timescales and are central to the ecological function of a soil (Karlen et al. 1994; Bandick and Dick 1999). Soil enzyme activities in particular are increasingly used as indicators of soil quality because of their relationship to decomposition and nutrient cycling, ease of measurement, and rapid response to changes in soil management (Dick 1994; Dilly et al. 2003). In a long-term study, Kandeler et al. (1999) found that enzyme activities were significantly increased in the top 10 cm of the profile after only 2 years of minimum and reduced tillage compared to conventional tillage. In contrast, significant effects of tillage treatments on microbial biomass, nitrogen (N) mineralization, and potential nitrification were not observed until after 4 years. Soil disturbance, however, is only one of the many factors affecting soil microbial and biochemical properties. Seasonal fluctuations in soil moisture, temperature, and substrate availability can also have large effects on microbial biomass and activity. Franzluebbers et al. (1994) found that soil microbial biomass carbon (C mic ) changed significantly during the cropping season in all crop sequences D. Geisseler (*) : W. R. Horwath Department of Land, Air, and Water Resources, University of California, Davis, PES Building, 1 Shields Ave, Davis, CA 95616, USA e-mail: djgeisseler@ucdavis.edu and tillage regimes under investigation. Bausenwein et al. (2008) also reported significant effects of sampling date on C mic and enzyme activities under minimum tillage. These observations raise the question of whether microbial and biochemical properties are affected by too many factors and fluctuate too much during the course of a season to be sensitive indicators of tillage-induced effects on soil quality. In general, conservation tillage (CT) practices leave a significant amount of plant residue on the soil surface. This results in an increased soil organic matter content in the topsoil, which in turn leads to higher microbial biomass and activity. This increase in organic matter content in the topsoil however is often offset with a decrease in lower soil layers (Dick 1992; Omidi et al. 2008). Franzluebbers (2002) suggested using changes in soil organic C with depth rather than the total amount of soil organic C in the profile as indicators of tillage-induced effects on soil properties. The stratification ratio, calculated by dividing the value for a soil property in the topsoil by its value in the subsoil, could not only be a more sensitive way to measure tillage-induced changes, but it also normalizes for differ- ences in climatic conditions and soil types between study sites. Because surface organic matter is essential to erosion control and water infiltration, the degree of stratification is directly linked to soil quality (Franzluebbers 2002). The objective of this study was to compare short-term dynamics of soil C, microbial biomass, and soil enzyme activities with longer-term effects of tillage in irrigated row crops in order to determine how environmental factors affect the use of these properties as sensitive indicators of tillage-induced changes in soil quality. A field trial was designed to test the following hypotheses: (1) enzyme activities and microbial biomass N (N mic ) respond more rapidly to differences in tillage treatments than total soil C.

Soluble Solids, Acidity, Canopy Fruit Distribution, and Disease Susceptibility of Selected Grape Cultivars in Quebec

ABSTRACT Twenty grapevine genotypes (‘Chancellor’, ‘Delisle’, ‘ES-6–12–28’, ‘ES-4–7–25’, ‘GR-7’, ‘Hibernal’, ‘Sabrevois’, ‘Kay Gray’, ‘Lucie Kuhlmann’, ‘Michurinetz’, ‘Okanagan Riesling’, ‘Prairie Star’, ‘St. Croix’, ‘St. Pepin’, ‘Seyval Noir’, ‘Seyval Blanc’, ‘SV-18–307’, ‘Vandal-Cliche’, ‘Vidal Blanc’, and ‘Siegerrebe’) were evaluated under different winter protection methods in Frelighsburg, Quebec, Canada. The effects of these methods on soluble solids, acidity, fruit canopy distribution, and susceptibility to diseases were evaluated. Significant differences in juice composition was observed among the tested cultivars, and a significant interaction was observed between cultivar and sampling date, indicating that the effects of sampling date and cultivar are not independent. SSC/acid ratio increased with a corresponding decrease in acidity and the hardy and semi-hardy cultivars Lucie Kuhlmann, Michurinetz, and Geneva Red produced the highest °Brix values. None of the tender cultivars had values exceeding 19.5 °Brix. A decrease in acidity was observed for all cultivars as ripening progressed except for ‘Seyval Blanc’, ‘St. Pepin’, ‘St. Croix’, and ‘SV-18307’, which showed little or no reduction in acidity during the last three sampling dates. Under the climatic conditions observed in this study, ‘Prairie Star’, ‘ES-4–7–25’, ‘Geneva Red’, ‘St. Pepin’, ‘Delisle’, ‘ES-6–12–28’, ‘Vandal Cliche’, ‘Kay Gray’, ‘Lucie Kuhlmann’, ‘Okanagan Riesling’, and ‘SV-18–307’ had acceptable SSC and TA values. No clusters were observed at a wire level above 175 cm in any of the winter protection systems. In the M1 and M2 treatments, almost all the cultivars produced the highest proportion of clusters at a height of 80 to 125 cm and minimum fruit clusters close to the ground. Unlike the M1 and M2 methods, the M3 winter protection approaches produced a wide distribution of fruit in the canopy. ‘Michurinetz’ had the highest powdery mildew infection, followed by ‘Siegerrebe’ and ‘Lucie Kuhlmann’, whereas ‘Prairie Star’, ‘ES 4–7–25’, ‘St. Croix’, ‘St. Pepin’, ‘Vandal Cliche’, ‘Hibernal’, ‘Okanagan Riesling’, and ‘Seyval Noir’ exhibited low susceptibility. No powdery mildew symptoms were noted in ‘Sabrevois’, ‘Delisle’, ‘Kay Gray’, ‘ES-6–12–28’, ‘Chancellor’, ‘SV-18307’, or ‘Seyval Blanc’.

ZOYSIAGRASS (ZOYSIA SPP.) RESISTANCE TO FALL ARMYWORM (SPODOPTERA FRUGIPERDA): POLYPHENOLS AND FLAVONOIDS ¿ COMPONENTS OF RESISTANCE

ZOYSIAGRASS (ZOYSIA SPP.) RESISTANCE TO FALL ARMYWORM (SPODOPTERA FRUGIPERDA): POLYPHENOLS AND FLAVONOIDS ¿ COMPONENTS OF RESISTANCE

Production and Quality of Forage and Economics of Grazing a Hay Meadow in the Spring

AbstractAn experiment was conducted to determine the effects of spring grazing on forage DM production and nutritive value, as well as the economics of spring grazing a flood-irrigated hay meadow. Two vegetation types were present: predominantly ‘Garrison’ fcreeping foxtail (Alopecurus arundinanceus Poir) and a complex mixture with both introduced and native species. With use of cages, samples of ungrazed and grazed treatments were collected before and after grazing and also in August. Eighty-eight Angus × Gelbvieh rotationally-crossed heifers (average BW = 361.3 kg) were allowed to graze from May 27 to June 8 at 5.4 heifers/ha. A sampling date effect (P < 0.0001) occurred for forage DM production. Forage DM production was not different (P = 0.90) between native species and creeping foxtail. Also, grazing treatment did not alter (P = 0.23) forage DM production. Vegetation types were not different (P . 0.19) in ash, NDF, ADF, and CP, but creeping foxtail was greater (P = 0.02) in in vitro DM digestibility than the native species group. The loss of 12,025kg of forage due to early grazing treatment, at a hay price of $0.0772/kg, resulted in a replacement hay value of $928. Forage plants were able to adequately recover from grazing despite atypical environmental conditions; however, expected improvements in quality did not occur with the early grazing treatment. It is concluded that although spring grazing by beef heifers did not affect forage production and most indices of forage quality, less harvestable nutrients in late summer were more costly than feeding harvested forage or renting pasture for the spring-grazing period.

Effects of sampling date, gender, and tick burden on peripheral blood cells of captive and wild tuatara (Sphenodon punctatus)

The aims of this study were: (1) to examine changes in immune parameters in tuatara (Sphenodon punctatus) sampled three times between winter and spring and (2) to examine the possible effects of gender and tick burden on peripheral blood cells. The three blood samples were taken from each of two male and two female captive tuatara at 4‐ to 6‐week intervals from July through October 2003. A single blood sample was also obtained from each of 39 wild tuatara captured on Stephens Island in October of the same year. For each blood sample of captive and wild tuatara, total leukocyte and erythrocyte counts were made with the aid of a haemacytometer and differential leukocyte counts were made from Giemsa stained blood smears. Among captive tuatara, counts of total leukocytes (WBC), heterophils, and lymphocytes varied between samples but with an insignificant increase from winter into spring. Wild tuatara had lower numbers of erythrocytes (RBC) compared with captive tuatara, accompanied by a larger number of erythrocyte precursors, more so in wild females than males. In wild tuatara, an increase in total leukocytes (WBC) was associated with tick burden.

Maternal micronutrient status and decreased growth of Zambian infants born during and after the maize price increases resulting from the southern African drought of 2001–2002

To investigate the effects on maternal micronutrient status and infant growth of the increased maize prices that resulted from the southern African drought of 2001-2002. Longitudinal cohort study. A maternal and child health clinic in Lusaka, Zambia. Maternal and infant health and nutrition data and maternal plasma were being collected for a study of breast-feeding and postpartum health. Samples and data were analysed according to whether they were collected before (June to December 2001), during (January 2002 to April 2003) or after (May 2003 to January 2004) the period of increased maize price. Season and maternal HIV status were controlled for in analyses. Maize price increases were associated with decreased maternal plasma vitamin A during pregnancy (P = 0.028) and vitamin E postpartum (P = 0.042), with the lowest values among samples collected after May 2003 (vitamin A: 0.96 micromol l(-1), 95% confidence interval (CI) 0.84-1.09, n = 38; vitamin E: 30.8 micromol mmol(-1) triglycerides, 95% CI 27.2-34.8, n = 64) compared with before January 2002 (vitamin A: 1.03 micromol l(-1), 95% CI 0.93-1.12, n = 104; vitamin E: 38.9 micromol mmol(-1) triglycerides, 95% CI 34.5-43.8, n = 47). There were no significant effects of sampling date on maternal weight, haemoglobin or acute-phase proteins and only marginal effects on infant weight. Infant length at 6 and 16 weeks of age decreased progressively throughout the study (P-values for time of data collection were 0.51 at birth, 0.051 at 6 weeks and 0.026 at 16 weeks). The results show modest effects of the maize price increases on maternal micronutrient status. The most serious consequence of the price increases is likely to be the increased stunting among infants whose mothers experienced high maize prices while pregnant. During periods of food shortages it might be advisable to provide micronutrient supplements even to those who are less food-insecure.

Ergovaline concentration in perennial ryegrass infected with a lolitrem B‐free fungal endophyte in north‐west Spain

Ergovaline concentrations in two perennial ryegrass genotypes (EI 19 and EI24) infected with one lolitrem B‐free fungal endophyte were determined over a 3‐year period at two different locations in north‐west Spain. There was a significant sampling date effect over 3 years and two locations (P < 0.05). The mean ergovaline concentrations ranged from 0.06 ppm in early spring to 0.57 ppm in June. EI19 genotype had significantly (P < 0.05) higher ergovaline concentrations (0.37 ppm, SE = 0.09) than EI24 genotype (0.33 ppm, SE = 0.08) only at one location in year 2000. Under north‐west Spanish conditions, ergovaline levels obtained in this study were not so high to reach values potentially toxic for animals. The results presented in this paper suggest that agriculturally useful ryegrass endophyte associations can be developed free from lolitrem B, and which do not accumulate excessive concentrations of ergovaline.

Date and Plant Community Effects on Elk Sedge Forage Quality

Elk sedge (Carex geyeri Boott) is one of the most important livestock and big game forages in many areas of the western U.S. It is one of the most prominent forage species in the diets of cattle and elk utilizing forested rangelands. Despite its acknowledged ecological and economical importance, very little is known about the factors influencing the forage quality of elk sedge. Effects of sampling date, plant community, and their interaction on the neutral detergent fiber, acid detergent fiber, and crude protein levels of elk sedge are reported for samples collected at the Starkey Experimental Forest and Range and the Bridge Creek Wildlife Management Area, both in northeastern Oregon, during January, April, July, and October of 1997 and 1998. Neutral detergent fiber levels in elk sedge were lowest in mid-October (average = 71.3%) and highest in mid-July (average = 76.1%). Acid detergent fiber was lowest in elk sedge collected in mid-October (average = 37.3%) and highest in mid-July (average = 39.0%) and mid-January (average = 39.2%). Elk sedge from the Douglas-fir/ninebark community was lowest in acid detergent fiber (average= 38.1%). Crude protein was highest (average = 8.0%) in mid-July elk sedge samples and lowest (average = 5.7%) in mid-January samples. Elk sedge from the ponderosa pine/fescue community was lowest in crude protein (average = 5.9%). All forage quality parameters exhibited variability between years. Although sampling date and plant community effects were detected, the forage quality of elk sedge appeared relatively stable compared to other native forages. A more intensive spring sampling campaign is needed to characterize the relationship between elk sedge phenology and forage quality dynamics. DOI:10.2458/azu_jrm_v56i1_clark

Date and plant community effects on elk sedge forage quality

Elk sedge (Carex geyeri Boott) is one of the most important livestock and big game forages in many areas of the western U.S. It is one of the most prominent forage species in the diets of cattle and elk utilizing forested rangelands. Despite its acknowledged ecological and economical importance, very little is known about the factors influencing the forage quality of elk sedge. Effects of sampling date, plant community, and their interaction on the neutral detergent fiber, acid detergent fiber, and crude protein levels of elk sedge are reported for samples collected at the Starkey Experimental Forest and Range and the Bridge Creek Wildlife Management Area, both in northeastern Oregon, during January, April, July, and October of 1997 and 1998. Neutral detergent fiber levels in elk sedge were lowest in mid-October (average = 71.3%) and highest in mid-July (average = 76.1%). Acid detergent fiber was lowest in elk sedge collected in mid-October (average = 37.3%) and highest in mid-July (average = 39.0%) and mid-January (average = 39.2%). Elk sedge from the Douglas-fir/ninebark community was lowest in acid detergent fiber (average= 38.1%). Crude protein was highest (average = 8.0%) in mid-July elk sedge samples and lowest (average = 5.7%) in mid-January samples. Elk sedge from the ponderosa pine/fescue community was lowest in crude protein (average = 5.9%). All forage quality parameters exhibited variability between years. Although sampling date and plant community effects were detected, the forage quality of elk sedge appeared relatively stable compared to other native forages. A more intensive spring sampling campaign is needed to characterize the relationship between elk sedge phenology and forage quality dynamics.