Search

Haskap (Lonicera caerulea L.) is a relatively new berry crop in North America, and little research exists regarding its postharvest storage characteristics or storage life. Postharvest changes in berry quality, and principal factors limiting storage life at 1.1 °C and 95% relative humidity, were evaluated up to 14 days for three cultivars in 2019 and up to 28 days for six cultivars in 2020. Containerized berries were periodically assessed for soluble solids content (SSC), skin rupture force (SRF) (both 2019 and 2020) and flesh firmness, titratable acidity (TA), and Brix/acid ratio (B/A) (2020 only). External appearance was also evaluated both years, revealing berry shrivel as the primary factor negatively impacting visual appeal, followed distantly by low incidence of spoilage later in storage. All cultivars exhibited relatively constant postharvest SSC and decreasing SRF, flesh firmness, and TA (resulting in increasing B/A ratio). Postharvest quality differed slightly between years; relative SRF was consistent among cultivars while SSC was not. Some cultivars had a portion of shriveled berries at harvest, pointing to a need for cultivar-specific harvest indices. Mean days to slight shrivel for individual berries varied among cultivars evaluated, ranging from 7.5–21.9 d postharvest, with mean weight loss ranging from 1.2%–1.6% at this stage. Combined with group marketability estimates — set at a threshold of 10% severely shriveled berries — we estimate a storage life of 7–10 d for fresh haskaps. Additional research is needed to delineate maturation physiology and optimize harvest timing.

Here, we document the first record for Montana of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), a major agricultural and nuisance pest in many parts of the world. The insect was found overwintering in a private residence in January 2021 in Billings (Yellowstone Co.). A preliminary survey of sites in Billings from May to October 2021 confirmed the presence of H. halys within a radius of at least 11 km from the January detection. Putatively overwintering H. halys and adult bugs found across the city of Billings in the summer suggest the insect may have been present in the area prior to 2021. Surveys conducted in various regions of the state between 2013 and 2020 reported no detections of H. halys. Yellowstone Co. was previously surveyed in 2017, indicating the species likely arrived between 2018 and 2020 or was present before 2018 at densities too low to be detected. The summary of presence and absence records we provide herein is valuable for future monitoring and management efforts of this economically important species.The publisher's final version of this work can be found at https://doi.org/10.1093/jipm/pmac024. Deposited by shareyourpaper.org and openaccessbutton.org. We've taken reasonable steps to ensure this content doesn't violate copyright. However, if you think it does you can request a takedown by emailing help@openaccessbutton.org.

Downy brome (Bromus tectorum L., syn. cheatgrass) is a winter annual grass that invades North American cropping, forage, and rangeland systems. Control is often difficult to achieve, because B. tectorum has a large seedbank, which results in continuous propagule pressure. Pyrenophora semeniperda (Brittlebank and Adam) Shoemaker, a soilborne fungal pathogen, has been investigated as a biological control for B. tectorum, because it can kill seeds that remain in the seedbank, thereby reducing propagule pressure. Temperature influences P. semeniperda and has not been investigated in the context of seeds collected from different B. tectorum locations, that may vary in susceptibility to infection. We compared the effects of temperature (13, 17, 21, 25 C) and B. tectorum seed locations (range, crop, subalpine) with different mean seed weights on infection rates of P. semeniperda using a temperature-gradient table. Infection differed by seed location (P < 0.001) and temperature (P < 0.001), with lighter-weight seeds (i.e., range and subalpine) more susceptible to P. semeniperda infection. Infection increased as temperature increased and was higher at 21 C (66.7 ± 6.7%) and 25 C (73.3 ± 6.0%). Germination was affected by seed location (P < 0.001) and temperature (P = 0.019). Germination was highest for the crop seed location (45.4 ± 4.2%) and overall decreased at higher temperatures (21 and 25 C). Our results suggest that B. tectorum seeds from a crop location are less affected by P. semeniperda than those from range and subalpine locations. Moreover, this demonstrates a temperature-dependent effect on all populations.

This is the peer reviewed version of the following article: [Carr, P.M., Boss, D.L., Chen, C., Dafoe, J.M., Eberly, J.O., Fordyce, S., Hydner, R.M., Fryer, H.K., Lachowiec, J.A., Lamb, P.F., et al. (2020). Warm‐season forage options in Northern Dryland Regions. Agronomy Journal.], which has been published in final form at https://doi.org/10.1002/agj2.20261. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions: https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html#3. Deposited by shareyourpaper.org and openaccessbutton.org. We've taken reasonable steps to ensure this content doesn't violate copyright. However, if you think it does you can request a takedown by emailing help@openaccessbutton.org.

Wheat streak mosaic, caused by Wheat streak mosaic virus (WSMV; family Potyviridae), is the most important and common viral disease of wheat (Triticum aestivum L.) in the Great Plains of North America. WSMV is transmitted by the wheat curl mite (WCM; Aceria tosichella). We evaluated how mean daily temperatures, cumulative growing degree-days, day of the year, and surrounding alternative host identity affected WCM infestation and WSMV infection of wheat from late summer through early autumn in Montana, United States. Cumulative growing degree-days, warm mean daily temperatures (i.e., >10°C), and surrounding alternative hosts interacted to alter risk of WCM infestation and WSMV infection. Wheat surrounded by Bromus tectorum L. and preharvest volunteer wheat had WCM infestation and WSMV infection rates of 88% in years when the mean daily temperature was 15°C in October, compared with 23% when surrounded by bare ground, and

Research/Limitations/Implications: This research allows one to build their own customized hospitality robot under U.S. $2,000. Given the cost of building the robot, it has limitations on the hospitality tasks it can perform. It can navigate on flat surfaces, has limited vision and speech processing capabilities and has a battery life not exceeding an hour. Furthermore, it does not have any robotic manipulators or tactile processing capabilities.

Plant genotype, age, size, and environmental factors can modify susceptibility and tolerance to disease. Understanding the individual and combined impacts of these factors is needed to define improved disease management strategies. In the case of Wheat streak mosaic virus (WSMV) in winter wheat, yield losses and plant susceptibility have been found to be greatest when the crop is exposed to the virus in the fall in the central and southern Great Plains. However, the seasonal dynamics of disease risk may be different in the northern Great Plains, a region characterized by a relatively cooler fall conditions, because temperature is known to modify plant–virus interactions. In a 2-year field study conducted in south-central Montana, we compared the impact of fall and spring WSMV inoculations on the susceptibility, tolerance, yield, and grain quality of 10 winter wheat varieties. Contrary to previous studies, resistance and yields were lower in the spring than in the fall inoculation. In all, 5 to 7% of fall-inoculated wheat plants were infected with WSMV and yields were often similar to uninoculated controls. Spring inoculation resulted in 45 to 57% infection and yields that were 15 to 32% lower than controls. Although all varieties were similarly susceptible to WSMV, variations in tolerance (i.e., yield losses following exposure to the virus) were observed. These results support observations that disease risk and impacts differ across the Great Plains. Possible mechanisms include variation in climate and in the genetic composition of winter wheat and WSMV across the region.

The Northern Great Plains of the United States and Canada have seen an increase in pulse crops like pea, lentil, and chickpea acreage in dryland and irrigated systems. Rotating pulse crops into cereal crop production systems could reduce the demand for nitrogen fertilizer due to the symbiotic relationship with nitrogen fixing bacteria called diazotrophs. Legume-diazotroph relationships are well studied, but little is known about the free-living bacteria of the bulk soil in the legume-cereal rotation systems. Here we determine the community structure of the overall (16S) and diazotroph (nifH) soil microbiome in pulse-cereal rotations across the state of Montana. Many variables influenced the microbial community structure, but and among them, irrigation caused a significant shift in the composition of the communities and co-occurrence network topology. Interestingly, the diazotrophic communities in dryland soil are more robust and contain more generalist compared to irrigated soils. Co-occurrence networks support the identification of different diazotrophic keystone taxa such as Firmicutes in irrigated and Proteobacteria in dryland soils. Linking farm management practices and crop productivity with microbial community structure dynamics is an initial step in establishing a knowledge base for farmers to exploit the soil microbiota to maintain healthy soil for crop production.

Management of vector-borne plant viruses requires understanding how abiotic (e.g., resource availability) and biotic (e.g., virus–vector interactions) factors affect disease via effects on epidemiological parameters that drive disease spread. We conducted two complementary experiments using Wheat streak mosaic virus (WSMV): (i) a field study to determine the effects of nitrogen (N) fertilization on winter wheat (Triticum aestivum L.) susceptibility to WSMV infection and (ii) a growth chamber study to evaluate the effects of N and carbon dioxide (CO2) enrichment on population growth rates of the wheat curl mite (WCM), the vector of WSMV, and whether the effects of nutrient addition on WCM reproduction were modified by WSMV infection. The relationship between N fertilization and plant susceptibility to WSMV infection was nonlinear, with infection rates increasing rapidly as soil nitrate increased from 0 to 20 ppm and more gradually at higher nitrate concentrations. In the growth chamber study, N fertilization increased WCM population growth rates when the vectors transmitted WSMV but had the opposite effect on nonviruliferous mites. CO2 enrichment had no observable effects on WCM populations. These results suggest that, whereas the spread of WSMV is facilitated by N addition, increases in atmospheric CO2 may not directly alter WCM populations and WSMV spread.

The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at sNN=200 GeV for harmonics n=1–4 in the pseudorapidity range |η

In this paper, we present a parallel tool for partitioning open-source relational databases. This tool is implemented with the goal of improving the performance and scalability of the relational databases. The tool provides a command line interface implemented in C and SQL and has been tested on both MySQL and PostgreSQL databases. The databases can be partitioned by the tool using the range, hash, or key partitioning schemes. To evaluate the performance gain from the developed partitioning tool, we tested our tool with each partitioning scheme using Select and Join queries on a real-world database - the homo_sapiens_core_92_38 database from the Ensembl genome browser.

One of the greatest virus disease threats to wheat production in the Great Plains of the USA is Wheat streak mosaic virus (WSMV). Breeding programs have developed wheat varieties that are resistant or tolerant to WSMV infection, but these characteristics are climate dependent, and may also vary by WSMV isolate. We tested 10 spring and nine winter wheat (Triticum aestivum) varieties and two barley (Hordeum vulgare) varieties for resistance and tolerance to one WSMV isolate over four years. In spring wheat and barley, there were year by cultivar interactions in terms of resistance and tolerance. However, in winter wheat, yield losses due to WSMV were relatively consistent across years and varieties. Additionally, we tested the impacts of three WSMV isolates individually and in a mixture on twelve, two, and twelve varieties of spring wheat, barley, and winter wheat, respectively. Resistance and tolerance varied by isolate and cultivar, but there were no isolate by cultivar interactions. For spring wheat and barley, yield impacts were greater for two of the three single isolates than for the isolate mixture, whereas in winter wheat, the isolate mixture caused greater yield losses than the individual isolates. Overall, the results indicate that resistance and tolerance phenotypes were influenced by environmental conditions and by WSMV isolate or combination of isolates, suggesting that cultivar screening should be conducted over multiple years and with multiple virus isolates.

Summary Understanding how weed communities assemble as a function of biotic and abiotic filters and transform through time has important implications for the sustainable management of agronomic systems. In a three-year study, we evaluated weed community responses to lucerne (Medicago sativa, perennial) vs. continuous spring wheat (Triticum aestivum, annual, CSW) and weed management practices where weeds in the CSW system were managed with three contrasting approaches (herbicide, tillage or sheep grazing). Our results indicated no differences in weed diversity between the perennial and annual crops or across the different management practices in CSW. However, there were differences in weed community composition. Lucerne, with the exception of the establishing year, impeded the growth and reproduction of several annual weeds, including Amaranthus retroflexus, Thlaspi arvense, Lamium amplexicaule and Chenopodium album, but favoured perennial broad-leaved weeds such as Taraxacum officinale and Cirsium arvense. The replacement of herbicide treatments in pre-plant and post-harvest in CSW with soil tillage or sheep grazing selected for different weed communities beyond the second year of establishment. The weed species driving the differences in CSW systems were Androsace occidentalis, more common in CSW managed chemically; Asperugo procumbens, more common in CSW managed with tillage; and T. officinale and Lactuca serriola, more common in CSW managed with sheep grazing. Understanding how cropping systems modify weed communities is a necessary step to shift from reactive weed control programmes to predictive management strategies.

Plant species-specific effects on soil biota and their impacts on subsequent plant growth, i.e. plant-soil feedbacks (PSFs, henceforth), are major drivers in natural systems but little is known about their role in agroecosystems. We investigated the presence and magnitude of PSFs in two contrasting agricultural settings and tested the importance of species identity and phylogenetic relationships in determining PSFs. We compared PSFs that developed from an intensified agricultural site and a nearby non-cultivated pasture. Four weed and seven crop species were grown in soil inoculated with either biologically active or sterilized soils from each system. Four crop response species were grown to estimate PSFs. PSFs were species-specific. The identity of currently- and previously-planted species and their interactions explained over 80 % of the variation in feedbacks. Biota from the intensified agricultural site produced negative feedbacks in three of the four response species. Phylogenetic relationships partially explained PSFs. PSFs can alter crop growth and may be altered by agricultural practices. The species-specific effect to soil biota should be taken into account when assessing the extent to which crop and weed species could influence subsequent plant growth.

In this paper, we present a high-level tool for partitioning open-source relational databases, thereby, enhancing their performance and scalability. The tool is implemented using Java and SQL, and has been tested on both MySQL and PostgreSQL databases. Our tool can be used through an interactive interface (both command-line interface and web-interface are supported ) and can help in automatically partitioning a given database using hash, key or range partitioning schemes. We evaluated the performance of the Select and Join queries before and after partitioning two real-world datasets - the U.S Department of Agriculture (USDA) food products database, and the Sloan Digital Sky Survey (SDSS) database. The results of this evaluation are presented in this paper. We also discuss the difference in performance of the queries before and after partitioning, and show the impact of the selection of different partitioning schemes - hash, key, range - on the performance of the queries. In some cases, a significant increase in query performance - up to 57% - is observed by partitioning the database tables appropriately.

Organic agricultural production has become a major economic and cultural force. However, in water-limited environments the tools used for weed control and nutrient supply, namely tillage and cover crops, may not be environmentally or economically sustainable as tillage damages soil and cover crops use valuable water. Thus, a major challenge has been finding appropriate ways to minimize tillage and terminate cover crops while still controlling weeds and obtaining cover crop ecosystem services. One approach to achieve this is through the economically viable integration of crop and livestock enterprises to manage weeds and terminate cover crops. In this article we (1) review research needs and knowledge gaps in organic agriculture with special focus on water-limited environments; (2) summarize research aimed at developing no-till and reduced tillage in organic settings; (3) assess approaches to integrate crop and livestock production in organic systems; and (4) present initial results from a project assessing the agronomic and weed management challenges of integrated crop-livestock organic systems aimed at reducing tillage intensity in a water-limited environment. The goal of eliminating tillage in water-limited environments remains elusive, and more research is needed to successfully integrate tactics, such as cover crops and livestock grazing to increase organic farm sustainability.

Summary Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2-, 3- and 4-year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3- and 4-year rotation systems than in the 2-year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life-history processes associated with soil seedbanks.

The environment in which a plant grows (maternal environment) can affect seed viability, germination, and dormancy. We assessed the effects of maternal environment on wild oat seed viability, germination, dormancy, and pathogen infection by collecting and analyzing wild oat seed from above and below a barley canopy at three field sites in Montana. The viability of wild oat seed collected below a crop canopy was consistently less than it was for seed from the overstory but varied among sites and years. Reductions in viability because of relative canopy position ranged from 10% to 30%. Effects of position relative to crop canopy on weed seed germination/dormancy rates varied by site and suggest that the direction and magnitude of the effects of maternal environment on dormancy depend on environmental conditions. These effects may be driven by crop competition or by changes in seed pathogen pressure or both. Seven species each of fungi and bacteria were isolated from wild oat seeds. The only fungi causing reductions in seed viability (15%) was isolated from understory seeds, and several bacteria from both overstory and understory sources reduced seed germination. Results suggest that, in addition to the known weed-suppressive effects of using taller or earlier emerging varieties of crops, such crops can reduce weed spread through effects on weed seed demography because weeds growing beneath the crop canopy produce a reduced amount of viable seed that is less likely to germinate in the following year.

Summary In winter wheat systems in the Northern Great Plains of the United States, Bromus tectorum and wheat streak mosaic virus (WSMV) commonly co-occur. While independent effects of these pests on wheat yields have been well documented, to our knowledge, no study has investigated whether WSMV modifies interactions between wheat and B. tectorum. Furthermore, the impact that environmental stressors such as nutrient availability have on these interactions has not been addressed. We conducted a randomised split-plot field study over 2 years to investigate the effects of WSMV and nitrate (N) availability on winter wheat suppression of Bromus tectorum. The study included four N treatments (10–19, 20–31, 31–84, and 85– 207 kg ha 1 ) and two WSMV treatments (mechanically inoculated or control). Increasing soil N increased the susceptibility of wheat to WSMV infection. In 2009, wheat in the lowest and highest N levels had 24% and 65% of plants infected respectively. However, regression analysis indicated that interactive effects of wheat competition, N and WSMV did not play a consistent role in B. tectorum growth. Specifically, the effect of both wheat density and distance from row on B. tectorum biomass remained constant across inoculation treatments, suggesting that wheat inoculated with WSMV suppressed B. tectorum as effectively as healthy wheat. Furthermore, wheat had a greater impact on B. tectorum growth in higher N environments, even though incidence of WSMV infection in wheat was highest. Overall, our results suggest that WSMV infection may not change the ability of wheat to suppress B. tectorum.

Summary Over-winter mortality, that is, winterkill, reduces cereal crop competitive ability and yield. While management and environmental variables are known to affect winterkill, the extent to which weeds contribute to increased winterkill is largely unknown. Winter annual weeds may increase winterkill through resource competition and by increasing incidence of and damage from plant pathogens that cause winterkill. We evaluated the impact of summer annual (Avena fatua) and winter annual (Bromus tectorum) weeds on the over-winter survival rate of winter wheat over three winters, during which plots were covered with snow. Pink snow mould (Microdochium nivale), a winterkill pathogen known to infect B. tectorum and winter wheat, was common in wheat stands. In weed-free treatments, mortality rates were initially near zero, but increased by nearly 45% in each subsequent winter, presumably due to an increase in snow mould disease in continuously cropped winter wheat. Whereas A. fatua infestation had no impact on crop survival rates, winter wheat survival in B. tectorum-infested plots was 50% less than the weed-free control in the second and third years of this study. Among B. tectorum-infested plots, winter wheat over-winter survival declined with increasing weed seed produced in the previous summer. Overall, this study demonstrated that winter annual weed infestations can reduce crop stand densities below replanting thresholds by reducing fall-sown cereal winter survival. The effects of winter annual weeds on winter wheat may be meditated by increased proliferation of snow mould disease.

Objective To study the phyto-constituents present in some selected medicinally important pteridophytes from the Western Ghats, India. Methods The dried and powered leaves materials (50 g) were extracted successively with 250 mL of petroleum ether, ethyl acetate, methanol, chloroform, acetone, benzene and water by using Soxhlet extractor for 8 h at a temperature not exceeding the boiling point of the solvent. The aqueous extracts were filtered using Whattman filter paper (No.1) and then concentrated in vacuum at 40°C using Rotary evaporator. The residues obtained were stored in a freezer −70°C until further tests. Phytochemical screening of the extracts was carried out according to the standard methods. Results The present study screened the phytochemical properties of ten plants with sixty six extracts and showed varied degree of phyto-constituents present. The presence or absence of the phyto-constituents depended upon the solvent medium used for extraction and the physiological property of individual taxa. Conclusions From these results, it can be concluded that the ten plants extracts may be used as broad-spectrum antimicrobial, bioactive agent after extensive investigation.

Objective To examine the phyto-constituents of Adiantum caudataum (A. caudataum), Adiantum latifolium (A. latifolium), Adiantum lunulatum (A. lunulatum), Christella dentata (C. dentate) and Christella parasitica (C. parasitica), to provide chemical marker and find inter- specific variation between the medicinally important genuses. Methods The dried and powered leaves materials (50 g) were extracted successively with 250 mL of petroleum ether, ethyl acetate, methanol, chloroform, acetone, benzene and water by using Soxhlet extractor for 8 h at a temperature not exceeding the boiling point of the solvent. The aqueous extracts were filtered using Whattman filter paper (No.1) and then concentrated in vacuum at 40 °C using Rotary evaporator. The residues obtained were stored in a freezer −70 °C until further tests. Phytochemical screening of the extracts was carried out according to the standard methods. Results A total of five plants and 30 extracts were examined for the phytochemical screening. The crude extracts of A. caudataum, A. latifolium, A. lunulatum, C. dentata and C. parasitica showed varied degree of phyto-constituents with reference to solvents of the plant extracts. A total of three plants and 18 extracts were examined for the phytochemical screening A. caudataum, A. latifolium, A. lunulatum. The steroid is totally absent in the tested extracts of A. lunulatum. Similar to that caoboxylic acid also absent in A. caudatum and Coumarin showed its presence only in A. caudatum. A total of two plants and twelve extracts were examined for the phytochemical properties of Christella. Of which phenol is present in 11 extracts tested. Steroid is present only in one extract of C. parasitica and coumarin is present only in C. parasitica five extracts. Conclusions The present study result provids a simple and cheap tool (Chemical marker) for the characterization and identification of the medicinally important taxa. With the help the phytochemical screenings we can find inter- specific variation between the medicinally important genuses and easily we can differentiate the Adiantum and Christella genuses.

Objective To evaluate the phytochemical properties of Azolla pinnata R. Br., Marsilea minuta L. and Salvinia molesta Mitch. Methods The dried and powered leaves materials (50 g) were extracted successively with 250 mL of petroleum ether, ethyl acetate, methanol, chloroform, acetone, benzene and water by using Soxhlet extractor for 8 h at a temperature not exceeding the boiling point of the solvent. Phytochemical screening of the extracts was carried out according to the standard methods. Results Out of eighteen tested extracts, eighteen extracts showed the presence of phenolics. Next to that, fourteen extracts were illustrated their existence of tannin. Ten extracts showed the occurrence of carbohydrates in the crude extracts of the selected plants. Steroid and saponin are present in eight extracts, next to that xanthoprotein is present in six extracts, followed by flavonoid and protein which are present in five extracts. Carboxylic acid showed its presence only in two extracts. Conclusions From the results, it can be concluded that the three plants extracts show the presence of many bioactive compounds after extensive investigation. We recommend further research on these plants to quantify the concentration of these compounds. Further work will accentuate the isolation and characterization of active principles responsible for bio-efficacy and bioactivity.

Damping-off disease can cause severe stand loss and reduce seedling vigour of kabuli chickpea (Cicer arietinum L.). While Pythium spp. are thought to be the primary cause of damping-off in chickpea, diversity and pathogenicity of other genera have not been widely explored. In surveys of three Montana fields of chickpea affected by damping-off, Fusarium spp. were isolated from 83% of the seeds tested, and were more common than the other taxa recovered, namely Pythium and Rhizopus. Fusarium spp. were identified to species using morphological characters and sequence analysis of two loci, the internal transcribed spacer (ITS) region of ribosomal DNA and the translation elongation factor (TEF) 1-α gene. Consistently identified species were F. oxysporum Schltdl. and F. redolens Wollenw. While discrepancies between identification methods made the identity of other isolates unclear, Fusaria infecting chickpea were diverse and varied across sites. The pathogenicity of eight isolates to kabuli chickpea was...

Tropical forests include a diversity of habitats, which has led to specialization in plants. Near Iquitos, in the Peruvian Amazon, nutrient-rich clay forests surround nutrient-poor white-sand forests, each harboring a unique composition of habitat specialist trees. We tested the hypothesis that the combination of impoverished soils and herbivory creates strong natural selection for plant defenses in white-sand forest, while rapid growth is favored in clay forests. Recently, we reported evidence from a reciprocal-transplant experiment that manipulated the presence of herbivores and involved 20 species from six genera, including phylogenetically independent pairs of closely related white-sand and clay specialists. When protected from herbivores, clay specialists exhibited faster growth rates than white-sand specialists in both habitats. But, when unprotected, white-sand specialists outperformed clay specialists in white- sand habitat, and clay specialists outperformed white-sand specialists in clay habitat. Here we test further the hypothesis that the growth-defense trade-off contributes to habitat specialization by comparing patterns of growth, herbivory, and defensive traits in these same six genera of white-sand and clay specialists. While the probability of herbivore attack did not differ between the two habitats, an artificial defoliation experiment showed that the impact of herbivory on plant mortality was significantly greater in white-sand forests. We quantified the amount of terpenes, phenolics, leaf toughness, and available foliar protein for the plants in the experiment. Different genera invested in different defensive strategies, and we found strong evidence for phylogenetic constraint in defense type. Overall, however, we found significantly higher total defense investment for white-sand specialists, relative to their clay specialist congeners. Furthermore, herbivore resistance consistently exhibited a significant trade-off against growth rate in each of the six phylogenetically independent species-pairs. These results confirm theoretical predictions that a trade-off exists between growth rate and defense investment, causing white-sand and clay specialists to evolve divergent strategies. We propose that the growth-defense trade-off is universal and provides an important mechanism by which herbivores govern plant distribution patterns across resource gradients.

Objective To examine the secondary metabolites present in the leaf extracts of Rhododendron arboreum Sm. ssp. nilagiricum (Zenker) Tagg. Methods Phytochemical screening of the leaf extract was done to determine the phytochemical constituents in the various solvents studied. Results The phytochemical study carried out on the leaf extracts of R. arboreum Sm. ssp. nilagiricum (Zenker) Tagg. confirm the existence of secondary metabolites such as phenols, saponins and tannins. Conclusions The study suggests that the leaf extracts of R. arboreum Sm. ssp. nilagiricum (Zenker) Tagg. can be best utilized in developing bioactive compounds against pathogenic infection.

Variation among plant species in the number of associated herbivore and pathogen species is predicted to fit a species-area relationship in which the area or biomass embodied by a plant species is a function of individual size and geographic range size. This hypothesis is tested using published estimates of geographic range, individual size, and species richness of fungal pathogens for 490 plant species occurring in the United States and controlling for sampling intensity and phylogenetic effects. The number of pathogens found on a plant species increases with the metrics of area and/or habitat diversity of plant species, and their effects are similar between gymnosperm and angiosperm lineages. The strength of this pattern across a diverse set of plant lineages suggests that accumulation and persistence of pathogen species on plant species are governed by similar processes among temperate plants.

Este estudio es una investigación comprensiva de la especialización por hábitat en plantas de los bosques tropicales y del papel de los herbívoros. Pusimos a prueba la hipótesis de que la alta presión de herbivorismo en los bosques tropicales intensifica las diferencias a lo largo de gradientes edáficos y causa una especialización por hábitat de escala más fina en las plantas. El sistema de estudio fue el mosaico de suelos sobre arena blanca pobres en nutrientes y de suelos de arcilla ricos en nutrientes en la Amazonía peruana. Planteamos la hipótesis de que el suelo empobrecido de arena blanca crea una fuerte presión selectiva hacia defensas de las plantas. Una alta inversión en defensas influye negativamente en el crecimiento, y de este modo las especies de arena blanca muy bien defendidas deberían ser superadas competitivamente en tipos de suelos más fértiles. Al mismo tiempo, plantas sin una inversión alta en defensas deberían estar excluidas por los herbívoros de los bosques sobre arena blanca. Inventarios en diferentes hábitats revelaron que la especialización edáfica es un patrón común en muchos grupos de árboles tropicales. Más aún, la especialización edáfica ha jugado un papel importante en la diversificación de las Burseraceas en la Amazonía, habiéndose producido especializaciones para cada tipo de suelo, muchas veces e independientemente. En relación con el papel de los herbívoros, descubrimos que los especialistas de arena blanca tienen una mayor resistencia a los herbívoros, y una tasa de crecimiento más baja. De este modo, los herbívoros acentúan las diferencias de los hábitats y, por tanto, incrementan las probabilidades de que la heterogeneidad edáfica produzca especialización por hábitat.

Objective To examine the phytochemicals present in the pericarp of Crataeva magna (C. magna) (Lour.) DC. which is used as a traditional medicine by the inhabitants of Kanyakumari district. Methods Phytochemical screening of the pericarp was done to determine the secondary metabolites in various solvents studied. Results The phytochemical screening on the pericarp of C. magna (Lour.) DC. proved the presence of phytochemicals such as phenols, saponins and tannins. Conclusions The findings of the present study recommended that the pericarp of C. magna (Lour.) DC. have potential antimicrobial compounds that may be of use for developing plant based drugs for various ailments.