The diagnosis and recommendation integrated system (DRIS) for diagnosing the nutrient status of grassland swards: I. Model establishment

Herbage analysis offers a definitive means of determining the N, P, K and S status of perennial ryegrass swards. Unfortunately, the results of such analyses can be difficult to interpret, simply because the minimum or 'critical' concentration of a nutrient in plant tissue for optimum growth, varies both with crop age and with changes in the concentrations of other nutrients. The Diagnosis and Recommendation Integrated System (DRIS) could help to improve the reliability of such interpretations. Diagnoses made using DRIS are based on relative rather than on absolute concentrations of nutrients in plant tissue, and as such should be comparatively independent of crop age.The aim of this study was to establish and test DRIS methodology for high-yielding perennial ryegrass swards. Because of prohibitive costs, setting up a whole new series of field experiments to evaluate DRIS model parameters for perennial ryegrass was out of the question. Instead, the diagnostic norms and associated coefficients of variation for the model were evaluated using data from a single (large) multi-factorial glasshouse experiment.Of the nutrient ratios selected to form the diagnostic norms, K/N and S/N had the clearest physiological rationale, whereas those involving Ca and Mg in combination with N, P, K and S appeared to have little physiological basis. It was reasoned, though, that because Ca and Mg uptake by plants are largely passive processes (ultimately governed by plant growth), the DRIS indices for these nutrients, together reflected the degree to which growth may be limited by non-nutritional (environmental) factors relative to nutritional ones. Both indices were combined to form a single reference (Rⁱ) index. Without such an internal reference, plant growth could be limited by multiple nutrient deficiencies, and yet N, P, K and S indices might all be close to, or equal to zero (i.e. the optimum), simply because the absolute concentrations of each nutrient (while low) had been in the correct state of balance. Moreover, by effectively using Ca and Mg as internal reference parameters in DRIS, 'nutrient concentrations' which previously formed the basis of the critical value approach, were essentially incorporated into the DRIS model, thus combining the strengths of the two diagnostic approaches; the only difference being that Ca and Mg, and not dry matter, were the internal references against which the levels of the major nutrients were compared.     

Diagnosis and Recommendation Integrated System Assessment of the Nutrients Limiting and Nutritional Status of Tomato

Tomato is an important field crop, and nutritional imbalances frequently reduce its yield. Diagnosis and Recommendation Integrated System (DRIS), uses ratios for nutrient deficiency diagnosis instead of absolute concentration in plant tests. In this study, local DRIS norms for the field tomatoes were established and the nutrient(s) limiting tomatoes yield were determined. Tomato leaves were analyzed for nutrients, to identify nutritional status using the DRIS approach. One hundred tomatoes fields were selected from Chatter Plain Khyber Pakhtunkhwa and the Sheikupura Punjab Pakistan. The first fully matured leaf was sampled, rinsed, dried and ground for analyzing P, K, Ca, Mg, Cu, Fe, Mn and Zn using an Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP AES). Plant tissue N and S were measured by the combustion method. The tomatoes yields were recorded at each location. The data were divided into high-yielding (≥3.79 kg/10 plant) and low-yielding (<3.79 kg/10 plant) populations and norms were computed using standard DRIS procedures. High-yielding plant population had a statistically greater mean S and Fe than the low-yielding population. The average balance index, the sum of functions, for S and Fe were −11.04 and −5.17 which reflected deficiency of S and Fe. Plant nutrients norms established may optimize plant nutrition in field tomatoes for high yield.     

Assessment of nutrient deficiencies in maize in nutrient omission trials and long-term field experiments in the West African Savanna

Low soil fertility is one of the main constraints to crop production in the West African savanna. However, the response of major cereals to fertilizer applications is often far below the potential yields. Low fertilizer efficiency, inadequacy of current fertilizer recommendations, and the ignorance of nutrients other than N, P, and K may limit crop production. Nutrient limitations to maize production were identified in on-farm trials in Togo and in several long-term experiments in Nigeria and Benin. Maize ear leaf samples were analyzed for macro and micro-nutrients, and the Diagnosis and Recommendation Integrated Systems (DRIS) was applied to rank nutrients according to their degree of limitation to maize. In the on-farm trials, both yield and DRIS results indicated that, when N is supplied, P limited maize production in all fields, reducing yields by 31% on average. Sulfur was limiting in 81% of the fields and was responsible for an average yield reduction of 20%. In the long-term experiments where N, P, and K had been annually applied, Ca and Mg indices were strongly negative, indicative of deficiency. Zn indices were negative in all trials. Despite N-fertilizer additions, N indices remained negative in some of the long-term experiments, pointing to low efficiency of applied fertilizers. There was a direct link between DRIS indices and the management imposed in the different experiments, indicating that DRIS is a useful approach to reveal nutrient deficiencies or imbalances in maize in the region.     

DRIS evaluation of persimmon (Diospyrus kaki L.)

The leaf macroelement profile of fruiting shoots of persimmon was characterized by a modified diagnostic and recommendation integrated system (DRIS), using SLW as a primary determinant of leaf mineral content. Leaf N, P, Ca, and Mg content was positively and linearly correlated with SLW when expressed on leaf area basis (g mm^–2). Potassium had a negative and higher correlation to SLW when expressed on %DW basis. Mineral ratios relevant for the DRIS analysis were calculated using all four possible combinations of Area (A) and Weight (W) expressions (A/A, A/W, W/A and W/W) and correlated with leaf SLW. The particular expressions chosen for the DRIS analysis were based on their highest correlation to SLW and included N/K, P/K and Ca/Mg, based on the A/W expression of the respective nutrients and the reciprocal expression (W/A) for all other ratios. Derivation of DRIS norms were based on the mineral profile of highly exposed shoots (SLW of 15.0±0.3 mg cm^–2). Calculated indices of gradually less exposed shoots (SLW of 3.8–18.9 mg cm^–2) revealed a strong exponential imbalance of N, K and P (increasingly positive) vs Ca and Mg (increasingly negative). The calculated Nutritional Imbalance Index (NII) value of leaves decreased exponentially as shoot leaf SLW decreased. The modified DRIS analysis detected successfully a distinct mineral profile of highly vigorous fruiting water shoots, as compared to regular fruiting shoots of comparable SLW.     

Evaluation of monitoring traps with novel bait for navel orangeworm (Lepidoptera: Pyralidae) in California almond and pistachio orchards

Experiments conducted in three almond, Prunus dulcis (Rosales: Rosaceae), orchards and three pistachio, Pistacia vera (Sapindales: Anicardiaceae), orchards in 2009 and 2010, and determined that sticky bottom wing traps baited with ground pistachio mummies, or a combination of ground pistachio plus ground almond mummies, trapped more adult female navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), than did traps baited with ground almond mummies alone. During both years of this study, 2.9 and 1.8 more moths were caught in traps baited with pistachio mummies compared with traps baited with almond mummies in almond orchards and pistachio orchards, respectively. Also, traps located in pistachio orchards caught 5.9 and 8.3 times more navel orangeworm than were trapped from almond orchards in 2009 and 2010, respectively. Implications for use of this novel baited trap in almond and pistachio orchard integrated pest management programs are discussed.     

Seasonal population dynamics of Draeculacephala minerva (Hemiptera: Cicadellidae) and transmission of Xylella fastidiosa

The grass sharpshooter, Draeculacephala minerva Ball (Hemiptera: Cicadellidae), is a very common and often abundant grass-feeding leafhopper in California. Its population dynamics and ability to transmit Xylella fastidiosa were monitored over a 2-yr period in California's San Joaquin Valley. Collections of individuals from natural populations in irrigated pastures and alfalfa, Medicago savita L. fields adjacent to X. fastidiosa-infected almond (Prunus spp.) orchards indicated the occurrence of three discrete generations per year that peaked during the summer. Population densities varied significantly among experimental field survey sites. Insects captured on intercepting mesh traps, yellow sticky cards, and UV-light traps indicated local movement of these insects into and surrounding X. fastidiosa-infected, almond orchards. Local movement and seasonal transmission of X. fastidiosa from infected almonds to Catharanthus roseus (L.) G. Don indicated that this insect may be partly responsible for the slow spread of almond leaf scorch now recently observed in California's San Joaquin Valley.     

Seasonal abundance of Draeculacephala minerva and other Xylella fastidiosa vectors in California almond orchards and vineyards

Almond leaf scorch (ALS) disease is caused by the bacterium Xylella fastidiosa and transmitted by xylem-feeding insects. Reports of increased incidence of ALS-diseased trees in California prompted surveys in three almond [Prunus dulcis (Mill.) D. A. Webb]-growing regions, from June 2003 to September 2005, to determine insect vector species composition and abundance. For comparison, sampling in and near vineyards in the San Joaquin Valley, California, also was completed. Sampling in or near almond orchards collected >42,000 Cicadomorpha of which 4.8% were xylem feeders, including 1912 grass sharpshooter, Draeculacephala minerva Ball; five Xyphon fulgida Nottingham; and a single spittlebug, Philaenus spumarius L. The most abundant vector was D. minerva. Season-long sampling indicated that D. minerva was a year-round resident in and/or near almonds in the Sacramento Valley, but not in the San Joaquin Valley. Similarly, D. minerca was rare in vineyards in the San Joaquin Valley, but was abundant in irrigated pastures near vineyards. D. minerva was most frequently collected along orchard margins, and peak densities were observed in summer, the period of time when bacterial titers are reported to increase in infected trees. Screening of D. minerva for presence of X.fastidiosa found that 1.1% of insects collected near almond orchards and 4.5% of insects collected from pastures tested positive. The X. fastidiosa subspecies and genotype detected in insects collected from orchards matched those collected from ALS-diseased almond trees in the same orchard. Of the few X. fulgida and P. spumarius collected, none tested positive for X. fastidiosa. Results are discussed with respect to X. fastidiosa vector control and detection methods.     

Nutrient cycling and foliar status in an urban pine forest in Athens, Greece

The nutrient cycling and foliar status for the elements Ca, Mg, K, N, P, S, Fe, Mn, Zn and Cu were investigated in an urban forest of Aleppo pine (Pinus halepensis) in 2004 in Athens, Greece in order to draw conclusions on the productivity status and health of the ecosystem. The fluxes of bulk and throughfall deposition were characterized by the high amounts of Ca, organic N and sulfate S. The magnitude of the sulfate S fluxes indicated a polluted atmosphere. The nutrient enrichment in throughfall was appreciable for ammonium N, P and Mn. The mineral soil formed the largest pool for all the elements followed by the forest floor, trunk wood and trunk bark. The understory vegetation consisting of annual plants proved important for storing N, P and K. Compared to current year needles of Aleppo pine in remote forests of Spain, the needles of the Aleppo pine trees in Athens had significantly higher concentrations of Ca, N, P and Cu and significantly lower concentrations of Mg and Zn. The soil had a high concentration of calcium carbonate and accordingly high pH values. When all inputs to the forest floor were taken into account, the mean residence time of nutrients in the forest floor followed the order Fe > Mn > Cu > Ca > Mg > P > Zn > N > K > S.     

The Binding Mechanisms and Inhibitory Effect of Intravenous Anesthetics on AChE In Vitro and In Vivo: Kinetic Analysis and Molecular Docking

Inhibitors of acetylcholinesterase (AChE), which have an important role in the prevention of excessive AChE activity and β-amyloid (Aβ) formation are widely used in the symptomatic treatment of Alzheimer's disease (AD). The inhibitory effect of anesthetic agents on AChE was determined by several approaches, including binding mechanisms, molecular docking and kinetic analysis. Inhibitory effect of intravenous anesthetics on AChE as in vitro and in vivo have been discovered. The midazolam, propofol and thiopental have shown competitive inhibition type (midazolam > propofol > thiopental) and Ki values were found to be 3.96.0 ± 0.1, 5.75 ± 0.12 and 29.65 ± 2.04 µM, respectively. The thiopental and midazolam showed inhibition effect on AChE in vitro, whereas they showed activation effect in vivo when they are combined together. The order of binding of the drugs to the active site of the 4M0E receptor was found to be midazolam > propofol > thiopental. This study on anesthetic agents that are now widely used in surgical applications, have provided a molecular basis for investigating the drug-enzyme interactions mechanism. In addition, the study is important in understanding the molecular mechanism of inhibitors that are effective in the treatment of AD.

     

Are San Jose scale (Hom., Diaspididae) pheromone trap captures predictive of crawler densities?

Abstract: Abundance of San Jose scale (SJS), Quadraspidiotus perniciosus (Comstock), adult males and crawlers were monitored with pheromone traps checked weekly and associated sticky tape traps monitored biweekly, respectively, in commercial almond orchards in Kern County, California, USA, during 1999 and 2000. Regression analysis was used to determine if SJS crawler abundance could be predicted from SJS males captured on pheromone traps. No significant relationship (P > 0.05) was indicated for any generation or for all SJS captured for the season in 1999. With greater replication in 2000, statistically significant relationships were indicated for the first generation (r = 0.727; F = 25.712; P < 0.0001; n = 25) and for all generations (r = 0.777; F = 63.239; P < 0.0001; n = 25). An additional orchard in 2000 was divided into 18 1.21‐ha plots with different treatments applied. A statistically significant relationship was indicated for the first generation (r = 0.507; F = 11.769; P = 0.0016; n = 36) and second generation (r = 0.436; F = 7.972; p = 0.0079; n = 36). These results suggest that relative densities of SJS crawlers on sticky tapes can be estimated using SJS male trap captures for the first generation, and that this approximation is appropriate for whole orchards or for subplots within orchards as small as 1.21‐ha.     

Effects of Selenium-Enriched Yeast Improved Aflatoxin B1-Induced Changes in Growth Performance,Antioxidation Capacity,IL-2 and IFN-γ Contents,and Gene Expression in Mice

Sixty Kunming mice were randomly assigned into three groups. Mice in a control group were fed a basal diet, while mice in AFB1 group and AFB1-Se group were fed the basal diet supplemented with 250 μg/kg AFB1 or the basal diet supplemented with 250 μg/kg AFB1 and 0.2 mg/kg selenium as selenium-enriched yeast, respectively. On day 30 of the experiment, growth performance, glutathione peroxidase (GSH-Px) activities, total antioxidant capacity (T-AOC) levels, and malondialdehyde (MDA) contents in liver, interleukin-2 (IL-2), and interferon-γ (IFN-γ) contents in serum, and cytochrome P3a11 (Cyp3a11), IL-2, IFN-γ, and GSH-Px1 mRNA levels in liver were determined. The results showed that final weights, weight gains, T-AOC levels, GSH-Px1, and IFN-γ mRNA levels in AFB1-Se group and control group were higher or significantly higher than those in AFB1 group (P < 0.05 or P < 0.01), respectively. Body length gains in AFB1 group were lower than those in the control group (P < 0.05), while there was no significant difference between the AFB1-Se and control groups (P > 0.05). IL-2 contents and liver IL-2 mRNA levels in AFB1-Se group were significantly higher than those in the AFB1 group and control group (P < 0.01), and IL-2 contents in the control group were also significantly higher than those in the AFB1 group (P < 0.01). IFN-γ contents in AFB1-Se group and AFB1 group were significantly higher than those in control group (P < 0.01), while IFN-γ contents in AFB1-Se group were significantly lower than those in AFB1 group (P < 0.01). Cyp3a11 mRNA levels in AFB1-Se group and AFB1 group were significantly higher than those in the control group (P < 0.01). The results indicated that selenium-enriched yeast could partly reduce the toxicity induced by AFB1 in mice, including improving growth performance, antioxidation capacity, IL-2 and IFN-γ contents, and enhancing IL-2, IFN-γ, and GSH-Px1 mRNA levels.

     

Enterocin M and Sage Supplementation in Post-weaning Rabbits: Effects on Growth Performance,Caecal Microbiota,Fermentation and Enzymatic Activity

The effects of enterocin (Ent) M and sage extract applied separately and in combination were investigated. EntM (E 50 μL/animal/day in water) and sage extract (S 10 μL/animal/day in water) were applied individually and in combination (E+S) to rabbits during 21 days of treatment. The rabbits’ growth was not significantly influenced by the additives. Lower feed conversion (FC) was noted in the experimental groups compared with controls, with the lowest data detected in E. The antimicrobial activity of EntM was noted (in E+S: lactic acid bacteria—P < 0.01; in E, E+S: enterococci, enterobacteria—P > 0.05; in E: clostridia—P > 0.05). The most significant changes in fermentation between weaned and older rabbits were noted in amylolytic activity at day 21 (E P < 0.05; E + S P < 0.05); prolonged reduction effect of sage extract on amylolytic activity was observed. The activity of cellulase, pectinase and xylanase was higher in older than in younger animals. Decrease in lactic acid and volatile fatty acids was noted during EntM administration, with significant effect on propionic acid concentration (E P < 0.05; E+S P < 0.001). The sage extract reduced propionic acid (S P < 0.001) and butyric acid levels (S P < 0.05) and increased the concentrations of butyric, iso-valeric, valeric, caproic acids and lactic acid (P < 0.001). It seems to be that EntM and sage supplementation may improve the economy of rabbit farms (increased FC) and the health status of rabbits (reduction of spoilage microbiota, enhanced enzymatic activities in caecum).

     

Expression of cellular protective proteins SIRT1, HSP70 and SOD2 correlates with age and is significantly higher in NK cells of the oldest seniors

Magnesium (Mg) and calcium (Ca) are the principal essential elements involved in endothelial cell homeostasis. Extracellular changes in the levels of either alter endothelial contraction and dilatation. Consequently Mg and Ca imbalance is associated with a high risk of endothelial dysfunction, the main process observed during acute aortic dissection (AAD); in this clinical condition, which mainly affects elderly men, smooth muscle cell alterations lead to intimal tears, creating a false new lumen in the media of the aorta. AAD patients have a high risk of mortality as a result of late diagnosis because often it is not distinguished from other cardiovascular diseases. We investigated Mg and Ca total circulating levels and the associated pro-inflammatory mediators in elderly AAD patients, to gain further information on the pathophysiology of this disorder, with a view to suggesting newer and earlier potential biomarkers of AAD. Total circulating Mg and Ca levels were both lower in AAD patients than controls (p < 0.0001). Using Ca as cut-off, 90% of AAD patients with low Ca (<8.4 mg/dL) came into the type A classification of AAD. Stratifying AAD according to this cut-off, Mg was lower in patients with lower total Ca. Compared to controls, both type A and B AAD patients had higher levels of all the pro-coagulant and pro-inflammatory mediators analyzed, including sP-sel, D-dimer, TNF-α, IL-6, and CRP (p < 0.05). Dividing types A and B using the Stanford classification, no significant differences were found (p > 0.05) The levels of both ICAM-1 and EN-1 were lower in AAD than in a control group (p < 0.0001 and p < 0.05 respectively). These findings suggest that low Mg and Ca in AAD elderly patients may contribute to altering normal endothelial physiology and also concur in changing the normal concentrations of different mediators involved in vasodilatation and constriction, associated with AAD onset and severity.     

Sedimentary Organic Carbon and Nitrogen Sequestration Across a Vertical Gradient on a Temperate Wetland Seascape Including Salt Marshes,Seagrass Meadows and Rhizophytic Macroalgae Beds

Coastal wetlands are key in regulating coastal carbon and nitrogen dynamics and contribute significantly to climate change mitigation and anthropogenic nutrient reduction. We investigated organic carbon (OC) and total nitrogen (TN) stocks and burial rates at four adjacent vegetated coastal habitats across the seascape elevation gradient of Cádiz Bay (South Spain), including one species of salt marsh, two of seagrasses, and a macroalgae. OC and TN stocks in the upper 1 m sediment layer were higher at the subtidal seagrass Cymodocea nodosa (72.3 Mg OC ha⁻¹, 8.6 Mg TN ha⁻¹) followed by the upper intertidal salt marsh Sporobolus maritimus (66.5 Mg OC ha⁻¹, 5.9 Mg TN ha⁻¹), the subtidal rhizophytic macroalgae Caulerpa prolifera (62.2 Mg OC ha⁻¹, 7.2 Mg TN ha⁻¹), and the lower intertidal seagrass Zostera noltei (52.8 Mg OC ha⁻¹, 5.2 Mg TN ha⁻¹). The sedimentation rates increased from lower to higher elevation, from the intertidal salt marsh (0.24 g cm⁻² y⁻¹) to the subtidal macroalgae (0.12 g cm⁻² y⁻¹). The organic carbon burial rate was highest at the intertidal salt marsh (91 ± 31 g OC m⁻² y⁻¹), followed by the intertidal seagrass, (44 ± 15 g OC m⁻² y⁻¹), the subtidal seagrass (39 ± 6 g OC m⁻² y⁻¹), and the subtidal macroalgae (28 ± 4 g OC m⁻² y⁻¹). Total nitrogen burial rates were similar among the three lower vegetation types, ranging from 5 ± 2 to 3 ± 1 g TN m⁻² y⁻¹, and peaked at S. maritimus salt marsh with 7 ± 1 g TN m⁻² y⁻¹. The contribution of allochthonous sources to the sedimentary organic matter decreased with elevation, from 72% in C. prolifera to 33% at S. maritimus. Our results highlight the need of using habitat-specific OC and TN stocks and burial rates to improve our ability to predict OC and TN sequestration capacity of vegetated coastal habitats at the seascape level. We also demonstrated that the stocks and burial rates in C. prolifera habitats were within the range of well-accepted blue carbon ecosystems such as seagrass meadows and salt marshes.

     

Concentrations and resorption patterns of 13 nutrients in different plant functional types in the karst region of south-western China

Background and Aims

Elucidating the stoichiometry and resorption patterns of multiple nutrients is an essential requirement for a holistic understanding of plant nutrition and biogeochemical cycling. However, most studies have focused on nitrogen (N) and phosphorus (P), and largely ignored other nutrients. The current study aimed to determine relationships between resorption patterns and leaf nutrient status for 13 nutrient elements in a karst vegetation region.

Methods

Plant and soil samples were collected from four vegetation types in the karst region of south-western China and divided into eight plant functional types. Samples of newly expanded and recently senesced leaves were analysed to determine concentrations of boron (B), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), N, sodium (Na), P, sulphur (S) and zinc (Zn).

Key Results

Nutrient concentrations of the karst plants were lower than those normally found in other regions of China and the rest of the world, and plant growth was mainly limited by P. Overall, four nutrients revealed resorption [N (resorption efficiency 34·6 %), P (48·4 %), K (63·2 %) and Mg (13·2 %)], seven nutrients [B (–16·1 %), Ca (–44·0 %), Cu (–14·5 %), Fe (–205·5 %), Mn (–72·5 %), Mo (–35·6 %) and Zn (–184·3 %)] showed accumulation in senesced leaves and two nutrients (Na and S) showed no resorption or accumulation. Resorption efficiencies of K and Mg and accumulation of B, Ca, Fe and Mn differed among plant functional types, and this strongly affected litter quality. Resorption efficiencies of N, P and K and accumulation of Ca and Zn increased with decreasing concentrations of these nutrients in green leaves. The N:P, N:K and N:Mg ratios in green leaves predicted resorption proficiency for N, K and Mg, respectively.

Conclusions

The results emphasize the fact that nutrient resorption patterns strongly depend on element and plant functional type, which provides new insights into plant nutrient use strategies and nutrient cycling in karst ecosystems.     

Geometry and bone mineral density determinants of femoral neck strength changes following exercise

Physical exercise induces spatially heterogeneous adaptation in bone. However, it remains unclear where the changes in BMD and geometry have the greatest impact on femoral neck strength. The aim of this study was to determine the principal BMD-and-geometry changes induced by exercise that have the greatest effect on femoral neck strength. Pre- and post-exercise 3D-DXA images of the proximal femur were collected of male participants from the LIFTMOR-M exercise intervention trial. Meshes with element-by-element correspondence were generated by morphing a template mesh to each bone to calculate changes in BMD and geometry. Finite element (FE) models predicted femoral neck strength changes under single-leg stance and sideways fall load. Partial least squares regression (PLSR) models were developed with BMD-only, geometry-only, and BMD-and-geometry changes to determine the principal modes that explained the greatest variation in neck strength changes. The PLSR models explained over 90% of the strength variation with 3 PLS components using BMD-only (R² > 0.92, RMSE < 0.06 N) and 8 PLS components with geometry-only (R² > 0.93, RMSE < 0.06 N). Changes in the superior neck and distal cortex were most important during single-leg stance while the superior neck, medial head, and lateral trochanter were most important during a sideways fall. Local changes in femoral neck and head geometry could differentiate the exercise groups from the control group. Exercise interventions may target BMD changes in the superior neck, inferior neck, and greater trochanter for improved femoral neck strength in single-leg stance and sideways fall.

     

三倍体毛白杨叶片营养DRIS诊断

采用L1645正交设计法对造林后的三倍体毛白杨进行了施肥试验,运用DRIS诊断法对其叶片营养元素进行了研究.结果表明,以造林第3年7～10月份三倍体毛白杨叶片N、P、K元素浓度测定值为依据,成功制定了DRIS图解法及指数法的营养诊断标准,经检验取得了较高的诊断正确率.三倍体毛白杨叶片N、P、K三元素浓度最佳比值范围为N/P=19.116±1.270;N/K=3.054±0.289;K/P=6.356±0.651.DRIS诊断标准分别经各月份林木叶片养分元素浓度回代检验,林木N、P、K需肥次序与实际施肥量基本一致,其中以9月份林木各处理为例,诊断正确率达到了80%以上.3年生三倍体毛白杨林木对N、P、K需求次序为N>K>P,与DRIS诊断结果一致.运用DRIS法诊断得到的三倍体毛白杨叶片养分浓度最佳比值范围将为三倍体毛白杨的合理施肥,大面积推广提供科学依据.     

Comparison of the volatile emission profiles of ground almond and pistachio mummies: Part 1 – Addressing a gap in knowledge of current attractants for navel orangeworm

Over the years various tissues of almond and pistachio have been evaluated for their ability to attract the navel orangeworm moth, a major insect pest in California tree nut orchards. Almond meal, which typically consists of ground almond kernels, is a monitoring tool for navel orangeworm populations in almond and pistachio orchards. Recently, ground pistachio and almond mummies have been re-visited in field trapping studies for their potential to attract navel orangeworm moths. Surprisingly, the volatile profiles of these two systems have not been reported. The objective of this study was to survey and then compare and contrast the volatile profiles of both ground almond and pistachio mummies over the course of a week. Principal component analysis (PCA) of the headspace volatiles showed a distinct difference between ground almond and pistachio mummies. The volatile emission profile of the almond mummies remained consistent over the one-week period, albeit in low content and composition; whereas the profile of the pistachio mummies changed over time as shown by PCA. Seven compounds were identified as being common volatiles to both matrices. These data may help explain results from recent navel orangeworm field trapping studies using almond and pistachio mummies, as well as with the formulation of future synthetic blends.     

Pollen collection by honey bee hives in almond orchards indicate diverse diets

Almond is one of the world's most economically valuable crops and many varieties require cross pollination for optimal fruit set. For this reason, western honey bee (Apis mellifera L.) hives are often placed in almond orchards. However, little is known about the usage of almond and other pollen sources by individual hives during almond bloom. Here, we investigated the timing, identity and quantity of pollen collection associated with almond floral abundance and spatial location of individual hives by sampling 440 individual pollen tray samples and counting 45,072 pollen grains from 13,200 pollen pellets collected from 80 individual hives across the flowering season in Victoria, south-eastern Australia. A large proportion of hives collected non-almond pollen in addition to almond pollen (63/80 = 79%). The weight of almond pollen collected by the hives at each sampling time was positively related to the number of concurrently open almond flowers. However, non-almond pollen richness and abundance was not related to the number of almond flowers but had a positive relationship with the weight of almond pollen collected. There was no relationship between the distance among hives and identity of pollen collected. Yet, three plant families in the study area were found to account for a high percentage of the non-almond pollen collected, Euphorbiaceae, Fabaceae and Asteraceae. Understanding crop and non-crop pollen collection could inform honey bee diet needs and identify the plant species of importance to inform best practice bee management during almond flowering.     

Improvement of almond production using Bombus terrestris (Hymenoptera: Apidae) in Mediterranean conditions

Almond trees are one of the most important crops in the Balearic Islands. The pollination of almonds is limited to the activity of insects, and cross‐pollination is necessary for fruit development. Currently, honey bees and wild bee populations are declining considerably due to multiple causes, such as the use of pesticides, diseases and habitat loss. An alternative to increase the almond production is the use of commercial pollinators. In this long‐term (3 years) study, the effect of the introduction of Bombus terrestris colonies on almond production was evaluated in two orchards. Two experimental designs were carried out to study the best management of this pollinator. For 2 years, all bumble bee colonies were placed in the middle of the plot and during the last year, the bumble bee colonies were distributed homogenously in the plot. Fruit set and the foraging behaviour of bumble bees during the blossoming period was determined, and the effect of different environmental variables on the visitation rate of bumble bees was assessed by means of a generalized linear mixed model (GLMM). Moreover, for the first time, the spatial distribution of fruit set was evaluated. Our results show that fruit set was significantly higher in the fields where B. terrestris had been introduced than in the control plots. This increased production resulted in a positive economic balance for the farmer. Moreover, bumble bees showed to prefer trees in a southwest orientation that were close to their colony. The activity of bumble bees showed to be significantly influenced by wind speed (the higher the speed the more flowers are visited by B. terrestris) and time after flowering (visitation rate decreased with days after flowering). In order to improve its management and obtain the highest possible almond production, it is important to understand the activity and behaviour of this pollinator.