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The increasing intrusion of weed species into alpine regions is an alarming threat to native floras because their strong and deep root systems cause a scarcity of nutrients to native alpine plant species. Considering the sensitive nature of alpine ecosystems, integrated weed management may be a means of preventing invasive species from going out of control. The present study investigated the allelopathic effect of Elsholtzia strobilifera on the germination and growth characteristics of Himalayan knotweed (Koenigia polystachya, syn. Polygonum polystachyum) under both field and laboratory conditions. The germination of seeds under laboratory conditions was studied by using different dilutions of hydrosol and aqueous extracts derived from E. strobilifera. In our field study, seedlings of K. polystachya were planted together with E. strobilifera in their natural habitat at a nursery. The study indicates that the seed germination and morphological parameters of seedlings were significantly inhibited by different dilutions of hydrosol and extract (reduction by 83–96% and 62–73%, respectively). In field conditions, significant inhibition in the morphological characteristics of K. polystachya was observed when grown in association with E. strobilifera. The results reveal that E. strobilifera has a significant allelopathic effect on K. polystachya. Based on the results of the present study, it can be concluded that growing plants of E. strobilifera around K. polystachya may be a novel approach to curbing the spread of the latter and suppressing the population of this species in ecologically sensitive alpine or other endangered areas. [ABSTRACT FROM AUTHOR]

Abstract Roots are crucial in plant adaptation through the exudation of various compounds which are influenced and modified by environmental factors. Buckwheat root exudate and root system response to neighbouring plants (buckwheat or redroot pigweed) and how these exudates affect redroot pigweed was investigated. Characterising root exudates in plant–plant interactions presents challenges, therefore a split-root system which enabled the application of differential treatments to parts of a single root system and non-destructive sampling was developed. Non-targeted metabolome profiling revealed that neighbour presence and identity induces systemic changes. Buckwheat and redroot pigweed neighbour presence upregulated 64 and 46 metabolites, respectively, with an overlap of only 7 metabolites. Root morphology analysis showed that, while the presence of redroot pigweed decreased the number of root tips in buckwheat, buckwheat decreased total root length and volume, surface area, number of root tips, and forks of redroot pigweed. Treatment with exudates (from the roots of buckwheat and redroot pigweed closely interacting) on redroot pigweed decreased the total root length and number of forks of redroot pigweed seedlings when compared to controls. These findings provide understanding of how plants modify their root exudate composition in the presence of neighbours and how this impacts each other’s root systems.

The functioning and upkeep of trophic chains in ecosystems, as well as the patterns and processes that shape biodiversity in the world, have all been attributed mostly to interactions between plants and animals. Wild plants play a very critical role by harboring the flagship species as native insect pollinators. Isodon coetsa is a suitable model to study differences in pollinator foraging behavior since it produces a large number of flowers that provide both nectar and pollen. Very few studies on understanding the diversity of flower visitors of Isodon plants have been performed. Our study recorded a total of 50 species of insects belonging to 36 genera, 18 families and 5 orders as the flower visitors of I. coetsa plants. Six functional groups of flower visiting insects were recorded during the present study viz. bees, vespids, butterflies, flies, beetles and bugs. Hymenoptera, Diptera and Lepidoptera were the most flower visiting insects recorded. Overall our study demonstrates the taxonomic diversity of insect flower visitors in a non-crop wild plant. Our results on ethological studies show functional synchronization of selected bee species in terms of flower handling time and overall visitation rates. Temporal variations of different insect flower visitors during the peak blooming time concludes the variation on the resource usage. On the avenue of resource utilization pattern of overall insect visitors, the majority were found to be dependent on nectar (61.54%) whereas the remaining gets both the nectar and pollen (38.46%). This observation depicts the role of I. coetsa in the local ecosystem as an essential resource provider to maintain local insect flower visitor diversity. [ABSTRACT FROM AUTHOR]

The structure of pollination networks is critical to ecosystem stability and functioning. We investigated pollinator-plant interactions to understand the foraging preference and develop pollination networks in a semi-arid rangeland of different grazing management categories in Tanzania. Along three line transects, each measuring 100 m, in each of the four grazing management categories (private and communal enclosures, wet and dry season grazing areas), we laid out three quadrats measuring 5 m x 5 m (25 m2,) located 30 m apart. We recorded insects visiting flowering plants for two consecutive days in each quadrat every week at each site from April to May, in 2019 and 2020. Aspilia mossambicensis received the most significant proportion of insect visitors (28%), followed by Justicia debile (21%). The mean protein concentration in sampled pollen varied significantly between plant species (χ² = 25.9, P = 0.001), with Solanum incanum containing the highest concentration (299.3 ± 0.68) g/100 g. We did not notice any correlation between honey bee visitation and protein concentration in pollen (r = −0.471, P = 0.239) nor with fatty acids concentration (r = 0.253, P = 0.546). When comparing pollinator-plant network properties including connectance, nestedness, robustness, number of links, modularity, network diversity and linkage density across rangeland management, we found that the private enclosure contained significantly larger networks than the communal enclosure, the dry and the wet season grazing sites. We conclude that particularly private enclosures are vital to promote pollination networks in our studied rangeland system as they include important pollinator forage plants.

ABSTRACT Perennial ryegrass is one of the most important food sources in animal production. However, several pests affect this crop, and one of the primary control strategies is the symbiotic relationships between ryegrass endophyte fungi. This fungus produces alkaloids that exhibit toxic activity against arthropods. Furthermore, the effect of fungi may extend to higher trophic levels, including predators (spiders and/or insects), decreasing their abundance and diversity. Given the importance of spiders and insects as predators, whether the symbiotic interaction between perennial ryegrass and endophyte fungus reduces the abundance and diversity of predators pose an important question. To address this question, natural enemies in perennial ryegrass were collected and analyzed over a year, and the percentage of endophyte fungus was evaluated by the presence of hyphae from two ryegrass cultivars, Jumbo (E-) and Alto AR1 (E+). We observed an 80% endophyte infection rate for (E+) and 0% for (E-). Moreover, 222 individual spiders corresponding to 10 families were identified in both perennial ryegrasses, including 209 individuals for (E-) and 13 for (E+). The most abundant spider family was Lycosidae, representing 71.17% of the total spiders. In addition, 65 insects were collected, corresponding to 6 families, with Carabidae being the most abundant. Furthermore, the Simpson index indicated the dominance of the family Lycosidae. Overall, spider and insect abundance and diversity were reduced in (E+), suggesting a negative effect of the endophyte on predator populations.

Previous studies have shown that plant–pollinator mutualistic interactions experience highly interannual variation. Given that pollinators often move across multiple plant species, the plant–plant interactions that take place via heterospecific pollen (HP) transfer may also vary temporally, which could have important implications for floral evolution and community assembly. Here, we evaluated the interannual variation in plant–pollinator networks and plant–plant heterospecific pollen transfer (HPT) networks of a subalpine meadow community in Southwest China for three consecutive years. The interactions largely varied among years for both network types. The composition of donor-species HP deposited on the plants varied less than did the visit composition of the pollinators, suggesting that HP could be transferred from identical donor species to recipient species through different shared pollinators among years. The plant species were at more similar positions in the HPT network than they were in the plant–pollinator network across years. Moreover, the more generalized plant species in the plant–pollinator network tended to export their pollen grains and more strongly influence HPT. We evaluated the relatively stable structure of the HPT network compared with the plant–pollinator network, which represents an important step in the integration of plant–pollinator and plant–plant interactions. [ABSTRACT FROM AUTHOR]

Among numerous soil problems, metals or trace elements (TEs) accumulation is one of the significant agronomic tasks which have extremely threatened food safety. Due to these, soil agronomists in recent times have also raised concerns over metal pollution, which indeed are obnoxious, disturbing the agricultural ecosystems and agricultural crops. Because metals are not biodegradable, they can survive in the environment, enter the food chain via crop plants, and accumulate in the human body through bio- magnification. Once harmful metals have accumulated over specifically permitted thresholds, they negatively impact microbiota density, composition, physiological activity, soil dynamics, and fertility, leading ultimately to a decrease in wheat production via the food chain, human and animal health. Overall wheat growth and yield decrease with an increasing quantity of TES. So, land contamination must be remedied as soon as possible. Phytoremediation is an environmentally benign strategy that could be a cost-effective solution to revegetate trace metal-polluted soil. Certain microorganisms, particularly those belonging to the plant growth-promoting rhizobacteria (PGPR) group, have been identified as having the unique property of metal tolerance and exhibiting unique plant growth-promoting potentials in order to reduce the magnitude of metal-induced changes. By delivering macro and micronutrients and secreting active biomolecules such as extracellular polymorphic substances (EPS), melanin, and metallothionein (MTs), such metal-tolerant PGPR have shown varying favorable impacts on wheat productivity in soils even contaminated with TEs. In this review, we explore the mechanisms by which metals are taken up, and their effect on plant growth, translocation, and detoxification in plants. We concentrate on the ways used to improve phytostabilization and phytoextraction efficiencies, such as genetic engineering, microbe-assisted, and chelate-assisted procedures. [ABSTRACT FROM AUTHOR]

Plants exhibit various behaviors of growth and allocation that play an important role in plant performance and social interaction as they grow together. However, it is unclear how Cucumis sativus plants respond to different neighbors. Here, we performed 5 neighbor combinations with C. sativus as the focal species. The selected materials of C. sativus responded to neighbors and exhibited different behavior strategies in a species-specific manner. All competition treatments reduced the growth of C. sativus seedlings to a certain extent, but only the Eruca sativa neighbor treatment reached a significant level in total root length and shoot biomass. Compared with growing under solitary conditions, focal plants avoided, tended to and did not change their allocation to their nearby plants. The larger the biomass of their neighbors, the stronger the inhibition of the focal plants. In addition, no significant correlations between growth and allocation variables were found, suggesting that growth and allocation are two important aspects of C. sativus behavioral strategies. Our findings provide reference and support for agricultural production of C. sativus, but further research and practice are still needed. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Among the weeds that interfere with the growth and development of sweet sorghum, beggar ticks stands out, because it has a high competitive capacity for the available resources. This study aims to compare the competitive ability of sweet sorghum (Sorghum bicolor (L.) Moench) against hairy beggarticks (Bidens pilosa L.), as a function of cultivar and plant proportion. Experiments were conducted in a greenhouse in a completely randomized design with four replications and six treatments. Treatments were arranged in replacement series in the proportions of 100:0, 75:25, 50:50, 25:75, and 0:100% (sorghum:weed) equivalent to 20:0, 15:5, 10:10, 5:15 and 0:20 plants per pot with 8 dm3 capacity of sweet sorghum (cultivars ‘BRS 506’, ‘BRS 509’ or ‘BRS 511’) against hairy beggarticks. Fifty days after emergence, plant leaf area (LA), aboveground dry mass (DM), photosynthesis (A), and transpiration rates (E) were measured. Competitive ability was analyzed by using the graphical analysis method and building diagrams based on total and relative productivity. Competitiveness, clustering coefficient, and aggressiveness were also determined. Sorghum cultivars, in general, showed losses independently of the proportion of hairy beggarticks. Statistical analysis showed small differences in competitive ability among sorghum cultivars; ‘BRS 509’ was also demonstrated to be slightly more competitive than ‘BRS 506’ and ‘BRS 511’ against hairy beggarticks. This, however, is unlikely to provide a competitive advantage for ‘BRS 509’ in production fields, and hairy beggarticks should be efficiently controlled early in the crop cycle to avoid productivity losses, independently of the sorghum cultivar.

The root microbiota plays a crucial role in plant performance. The use of microbial consortia is considered a very useful tool for studying microbial interactions in the rhizosphere of different agricultural crop plants. Thus, a consortium of 3 compatible beneficial rhizospheric Pseudomonas strains previously isolated from the avocado rhizosphere, was constructed. The consortium is composed of two compatible biocontrol P. chlororaphis strains (PCL1601 and PCL1606), and the biocontrol rhizobacterium Pseudomonas alcaligenes AVO110, which are all efficient root colonizers of avocado and tomato plants. These three strains were compatible with each other and reached stable levels both in liquid media and on plant roots. Bacterial strains were fluorescent tagged, and colonization-related traits were analyzed in vitro , revealing formation of mixed biofilm networks without exclusion of any of the strains. Additionally, bacterial colonization patterns compatible with the different strains were observed, with high survival traits on avocado and tomato roots. The bacteria composing the consortium shared the same root habitat and exhibited biocontrol activity against soil-borne fungal pathogens at similar levels to those displayed by the individual strains. As expected, because these strains were isolated from avocado roots, this Pseudomonas -based consortium had more stable bacterial counts on avocado roots than on tomato roots; however, inoculation of tomato roots with this consortium was shown to protect tomato plants under high-temperature stress. The results revealed that this consortium has side beneficial effect for tomato plants under high-temperature stress, thus improving the potential performance of the individual strains. We concluded that this rhizobacterial consortium do not improve the plant protection against soil-borne phytopathogenic fungi displayed by the single strains; however, its inoculation can show an specific improvement of plant performance on a horticultural non-host plant (such as tomato) when the plant was challenged by high temperature stress, thus extending the beneficial role of this bacterial consortium. [ABSTRACT FROM AUTHOR]

It is well established that plants can communicate with each other under different stressful conditions through (signals, cues, and rhizosphere interactions). Numerous studies have been conducted to find how plants respond to different neighbors at various points of genetic affiliation. Contrasting results and lack of molecular evidence in species recognition studies have made this topic more curious and complex. Some plant species compete more vibrantly for below-ground resources when an encounter with neighboring unrelated conspecifics as compared to related conspecifics (kin recognition). Some species increase competition when interacting with related and unrelated conspecifics (niche partitioning); some species do not show any change in the above/below ground allocation pattern. In this review, we attempt to provide a research background of species recognition in plants and plant communication, the current state of knowledge, and future perspectives. It has been established that species identification and communication between plants exist through many mediums like damage induced warnings, call for predators, root secretion, and volatile signaling. We found that most of the research has been executed in a controlled environment with a continuous supply of nutrients and water; more field studies should be conducted to assess the behavior of related/non-related conspecifics. Furthermore, not many studies have focused on kin related plant communication via volatile signals, protein interaction and cues. [ABSTRACT FROM AUTHOR]

Facilitative interactions occur between the plants in intercropping systems, however, the underlying allelopathy mechanisms are poorly understood. We determined the effects of potato-onion (Allium cepa var. agrogatum Don.) intercrop on root morphology of tomato (Lycopersicon esculenum L.) through volatile organic compounds (VOCs). There were four treatments as (i) Tomato/tomato without VOCs interaction (-TT), (ii) Tomato/tomato with VOCs interaction (+TT, control), (iii) Potato-onion/tomato without VOCs interaction (-OT) and (iv) Potato-onion/tomato with VOCs interaction +(OT) in glasshouses. As compared to tomato, VOCs from potato-onion significantly increased the number of root tips total length but decreased the root diameter of tomato, however significantly the increase the tomato root length (0-0.5 mm mean diameter). These results indicated that the tomato root morphology has influenced by aboveground secreted VOCs from neighboring plants in potato-onion intercropping system. [ABSTRACT FROM AUTHOR]

In a general way, galling insects can induce only one gall morphotype on the host plant species. However, some taxa of galling insects such as Eriococcidae can induce sexually dimorphic galls on the same host. In the present study, Lopesia mataybae (Diptera: Cecidomyiidae) induced two gall morphotypes on the leaflets of Matayba guianensis (Sapindaceae), a rare evidence of sexual dimorphism in galls induced by Cecidomyiidae. We investigated the adult emergence of galling insects and the morphological, histological, and histochemical attributes of the gall morphotypes. Both gall morphotypes showed the galling insect in the larval or pupal stage, and the insect adult emergence from different morphotypes was sexually distinct. Galls occupied by females (Globoid) were significantly larger (average height = 4.67 mm. S = 0.43/average width = 4.59 mm. S = 0.70) than galls occupied by males (cylindrical) (average height = 2.95 mm. S = 0.46/average width = 2.34 mm. S = 0.45). Both gall types were composed of elongated cells in the inner cortex and rounded cells in the outer cortex of the vessel-like structure. The globoid galls showed 42 cell layers (14 of them cylindrical, S = 3.86; 28 rounded, S = 5.89) and cylindrical galls showed 29 layers. There were no differences between morphotypes in the histochemical compounds detected. We have shown here significant morphological and histological differences between male and female galls possibly due to the different nutritional requirements of Lopesia mataybae sexes. Therefore, the expression of sexual dimorphism in gall morphotypes may be associated with developmental pathway differentiation between the sexes of L. mataybae. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciencias Agricolas is the property of University of Narino, Faculty of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plants exhibit various behaviors of growth and allocation that play an important role in plant performance and social interaction as they grow together. However, it is unclear how Cucumis sativus plants respond to different neighbors. Here, we performed 5 neighbor combinations with C. sativus as the focal species. The selected materials of C. sativus responded to neighbors and exhibited different behavior strategies in a species-specific manner. All competition treatments reduced the growth of C. sativus seedlings to a certain extent, but only the Eruca sativa neighbor treatment reached a significant level in total root length and shoot biomass. Compared with growing under solitary conditions, focal plants avoided, tended to and did not change their allocation to their nearby plants. The larger the biomass of their neighbors, the stronger the inhibition of the focal plants. In addition, no significant correlations between growth and allocation variables were found, suggesting that growth and allocation are two important aspects of C. sativus behavioral strategies. Our findings provide reference and support for agricultural production of C. sativus, but further research and practice are still needed.

• Plant distribution in dunes could be determined by soil salinity and phosphorus. • Plant performance may be influenced by the interactions they establish. • Ambrosia chamissonis is a competitive species in the extreme of the stress gradient. • Ammophila arenaria depend on facilitation to inhabit highly stressful areas. • Coastal dune plants do not always follow the stress gradient hypothesis. Coastal dunes are unique ecosystems distributed worldwide. They share coastline-to-inland abiotic stress gradients determining their plant´s spatial distribution and biological interactions. Ambrosia chamissonis and Ammophila arenaria dominate coastal dunes in Chile, but there is scarce ecological information about their interactions and spatial distribution. The aim of this study was to characterize the coexistence of these two species and to evaluate the effect of stress gradients on their spatial distribution and performance. The study was carried out in three coastal dunes of the Ñuble Region, Chile; two dunes in which each species dominates and one in which they coexist. In each dune, sampling sites were defined along study transects perpendicular to the coast, where both soil characteristics (pH, salinity, contents of water, organic matter, nitrogen, phosphorus, and potassium) and biological variables of each species (cover, height, water content, content of foliar macronutrients) were measured. Variation of each abiotic variable with the distance from the high tide level was correlated to determine environmental stress gradients. A Canonical Correspondence Analysis (CCA) was performed to determine soils characteristics that better explained changes in plant abundance. The Relative Interaction Intensity index was calculated from biological variables and compared intraspecifically to determine dominant interactions along the dunes. Our results showed two soil stress gradients (soil salinity and available potassium) which decreased inland and may define in part, the spatial distribution of the species, as shown by the CCA. Our results support the idea that dune plants do not always follow the stress gradient hypothesis suggesting a modification of the hypothesis. [ABSTRACT FROM AUTHOR]

Spatial arrangement is a key factor in maintaining community yield and stability via regulating component intra-/interspecific competition in an alpine climate environment. A 2-yr field trial was conducted on the Qinghai Tibetan Plateau, including cross row (S&#95;C), double row (S&#95;D), single row (S&#95;R), broadcast (M&#95;B), dependent row (M&#95;D) and independent row (M&#95;I). Our results showed that S&#95;C could avoid intraspecific competition by reasonable spatial arrangement, which favored the dominant component growth (1st year: leaf; 2nd year: stem and reproductive organ). For mixed communities, RII (relative interaction intensity) implied that interspecific competition also embodied on dominant component, and higher Elymus nutans component advantages seriously limited Onobrychis viciifolia's components growth in the 2nd year. More details displayed that E. nutans in M&#95;B or M&#95;D produced the maximum system yield via increasing leaf investment at the initial stages and stem investment after July 2019. Besides, M&#95;I possessed lower component numbers than M&#95;B and M&#95;D in the unit area. PCA analysis revealed that component numbers or biomasses changed synchronously, besides the E. nutans of S&#95;C, M&#95;B, and M&#95;D presented significant discrepancies compared to other treatments in September 2019, which verified the effect of sowing patterns on component growth (P < 0.05), but O. viciifolia in different sowing patterns was similar in the 2nd year. Considering the adaptability and production for the environment of the Qinghai Tibetan Plateau, S&#95;C is recommended for the promoted effect on component biomasses. M&#95;B and M&#95;D, with the merit of spacing utilization as well as higher resistance to variation in seasonal growth conditions via optimizing interspecific relationships for mixed communities, are adapted for increasing yield via component harvesting. Our results unveiled the potential of optimizing spatial usage efficiency via controlling component growth characteristics and stressed the importance of dynamic change of dominant components to enhance forage system production in alpine regions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nitrogen (N) is the important nutrition that regulatory plant functioning and environmental stability of invasive plant species under flooding (F) conditions. Little information clarifies the role of nitrogen enrichment and flooding on the invasive plant functional traits and competition with native competitors. Plant functional traits play an essential role in the successful growth of plants under different environmental conditions. Therefore, greenhouse pots experiment was conducted with invasive plant species (Wedelia trilobata, WT), and its native competitor (Wedelia chinensis, WC) in monoculture and cocultivation culture, along with flooding and nitrogen enrichment conditions. Considering the impact of flooding (F) and nitrogen (N) on an individual basis, the plant physiological traits of WC were nonsignificant compared to that of WT. However, in the combination of flooding × additional nitrogen (F.N, F.2N), plant physiological traits of WT were comparatively higher than those of WC, especially in cocultivation. In flooding × additional nitrogen (F.N and F.2N), better phenotypic plasticity at different plant traits makes WT more dominant in resource competition over WC. In conclusion, improved functional traits of WT under nitrogen enrichment and flooding conditions enhanced its competitiveness over native competitors.

Plant competition and deer browsing are two main factors which limit tree recruitment. We examined natural tree-recruitment processes under continuous-tree-cover management. Changes in plant communities and tree regeneration were monitored over an eight-year period at two different sites in a temperate hardwood forest in the North-East of France. We used paired control plot (unfenced areas, free access to deer) and exclosures (fenced areas, excluding deer) at both sites. Shade-tolerant browsing-tolerant opportunistic species (beech, Fagus sylvatica at site 1 and bramble, Rubus spp. at site 2) were present in low numbers at the beginning of the study. We found that these species used a sit-and-wait strategy, waiting for opportunities to proliferate (thinning and deer exclusion). In the exclosure at site 1, beech proliferate slowly. In the exclosure at site 2, bramble proliferated enough during the first two growing seasons to prevent tree recruitment. Thus, fencing encouraged beech sapling or bramble growth, and this growth in turn was detrimental to the richness and diversity of the plant community. The two study cases presented show that both plant competition and deer browsing can be problematic for tree recruitment. Our results further suggest that excluding deer is not sufficient to enhance the growth of browse-sensitive and moderately shade-tolerant tree species such as oaks (Quercus petraea and Q. robur).

Aims: Soils are known to be significant sources of atmospheric nitric oxide (NO), a key compound in atmospheric chemistry. NO is a key regulating substance for inter- and intra-species signalling and competition and affects plant growth and soil microbial metabolisms. However, little is known about NO concentration in soils and production of NO in the soil profile. Methods: Here we report on soil NO concentrations down to 65 cm soil depth and soil surface flux measurements over a 15 months period in subdaily resolution. This is supplemented by information on aerobic and anaerobic NO production in various soil layers of a spruce stand in SW Germany. Results: NO concentrations showed a clear seasonality with highest concentrations of up to 800 nmol mol−1 (or part per billion in volume mixing ratio; ppbv) at the interface between the organic Of-Oh sub-layers in the summer. NO concentrations in the mineral subsoil (−65 cm) were approx. One order of magnitude lower than in the organic layer. Dynamic changes of soil NO concentrations were closely correlated with soil surface NO fluxes. Differences in soil NO concentrations across the soil profile reflected differences in aerobic and anaerobic NO production potential. Conclusion: The importance of such high NO concentrations for soil microbial and plant physiological processes remains unclear, but should be addressed in future research in order to improve our understanding of microbe-microbe and plant-microbe interactions. [ABSTRACT FROM AUTHOR]

Ultraviolet filters (UVFs) added to sunscreens (SS) are emerging contaminants in marine environments due to their adverse effects on organisms and ecosystems. UVFs have also been detected in beach-dune systems, but their influence on resident organisms has not been explored yet. Native plants are fundamental components of coastal dunes, and these ecologically/economically important systems are currently among the most threatened globally. Thus, understanding whether UVFs may act as threats to dune plants is crucial. This field study evaluated and compared the effects of titanium dioxide nanoparticles (nTiO 2), one of the inorganic UVFs most commonly added to sunscreens, and those of a commercial sunscreen product containing it (SS-nTiO 2) on the performance of adult dune plants of a native (Thinopyrum junceum) and a non-native invasive species (Carpobrotus sp. pl.) and their competitive interactions at environmentally realistic concentrations. The effects of nTiO 2 , SS-nTiO 2 and of a sunscreen product containing just organic UVFs (SS-OF) on early life stages of T. junceum were also examined. Ti bulk content in sand and plants at the study site ranged from 970 to 1069 mg kg−1 and from 2 to 7.9 mg kg−1, respectively. Thinopyrum junceum adult plants periodically exposed during the summer season to seawater contaminated by SS-nTiO 2 produced less biomass than un-exposed plants and nTiO 2 exposed plants. nTiO 2 and SS-nTiO 2 reduced the capacity of T. junceum to control the spread of Carpobrotus. Both SS-nTiO 2 and SS-OF reduced seedling emergence in T. junceum whereas nTiO 2 did not. These results demonstrated that the periodical exposures of native dune plants to sunscreens could reduce their establishment success and growth and favor invasive plant spread potentially resulting in community structure changes. They also emphasize the need to assess the phytotoxicity not only of single UVFs but especially that of complete sunscreen products to design more eco-friendly formulations in the future. [Display omitted] • UVF and sunscreen (SS) are pollutants of emerging concern for coastal environments. • UVF nTiO 2 alone did not affect the growth of dune plants. • SS containing nTiO 2 reduced the growth of a native plant. • nTiO 2 and SS-nTiO 2 reduced native plant ability to control invasive plant spread. • SS-nTiO 2 and SS containing organic filters reduced native plant seedling emergence. [ABSTRACT FROM AUTHOR]

It is unclear how interspecific resource competition affects crop leaf senescence in association with nitrogen (N) remobilization and overyielding in semiarid intercropping systems. To address this issue, maize intercropped with soybean (weakly competitive species) and wheat (strongly competitive species) was examined across three consecutive years to explore the effects of resource competition on maize relative and absolute yield gain, leaf senescence traits, N remobilization and physiological activities in a typical semiarid site. High yield (171.8 g plant−1), relative yield (0.63) and net effect (0.99 t ha−1) of maize were observed in the maize soybean intercropping system, while the opposite trend was found in the maize wheat intercropping systems. Overall, maize benefited from intercropping with soybean but was negatively affected by intercropping with wheat. Interestingly, both intercropping systems significantly delayed the onset time of maize leaf senescence by approximately 5–20 days and prolonged the senescence duration by approximately 8–18 days. Intercropping with soybean increased maize leaf dry matter remobilization from 7.3 to 12.5 g per plant−1 and reduced N remobilization from 0.81 to 0.45 g plant−1, respectively. However, when intercropped with wheat, dry matter and N remobilization of maize leaves were decreased, at 4.8 and 0.13 g plant−1, respectively. Therefore, excessive delay and prolonged leaf senescence reduced leaf dry matter translocation and N to the grain which impaired yield formation. Our findings provided novel insights into the physiological mechanism of overyielding from the perspective of leaf senescence traits and remobilization function in the semiarid intercropping systems. [Display omitted] • Interspecific competition affects leaf senescence traits and N remobilization in maize. • Interspecific competition delayed the onset time and the duration of leaf senescence. • High competitiveness promoted physiological vigor in leaves, which promotes C&N remobilization. • Leaf senescence as affected by resource competition provides new insights into overyielding. [ABSTRACT FROM AUTHOR]

Aims: Invasive plants often modify soil biota to benefit their own fitness over native species, and create a positive plant-soil feedback (PSF). Rhizosphere effect (RE), the alterations of decomposition processes by living roots and associated rhizodeposits, may act as a mechanism that contributes to the positive PSF via accelerating litter decomposition and subsequent soil nutrient turnover. However, the relative effects attributable to litter quality versus plant composition and edaphic conditions on RE remain unclear. Methods: A reciprocal translocation decomposition experiment was conducted in a screenhouse with root litter from an invasive (Flaveria bidentis) and a native species (Bidens maximowicziana) in two types of soils (one dominated by the invasive species and another by the native species) with four plantings (two monocultures, one mixture with both species, and one without living plants). We examined the performance of invasive and native species responses to different soils (PSF) and quantified the RE on litter decomposition. Results: PSF and RE were dependent on whether focal species grew in the monocultures or mixture, and interspecific competition ameliorated negative PSF of F. bidentis when it competed with a weaker competitor. All RE values associated with B. maximowicziana litter under the monocultures were positive, whereas F. bidentis litter exhibited neutral to negative REs, mainly depending on the soil type examined. The RE values in the invaded soil were significantly greater than those in the native soil under the monocultures. However, mixture planting tended to decrease REs on decomposition, which in turn feedback to host plant by affecting soil N availability and microbial composition. Conclusions: Our study showed that innate differences between the two litters in terms of their decomposability and edaphic conditions are likely to exert a much greater impact in controlling litter decomposition. Importantly, rhizosphere-mediate belowground process has the potential to be an important contributor to plant-interaction outcomes. [ABSTRACT FROM AUTHOR]

Background and aims: Each genotype within species has a particular combination of root morphological and/or physiological traits to adapt to phosphorus-limited environments, which can lead to its unique plant fitness and competitive ability. Yet, how the various phosphorus environments affect the competition between genotypes remains obscure.Methods: Two maize (Zea mays L.) genotypes (XY335 and HMY, bred in nutrient-rich and nutrient-poor environments, respectively) were grown in monoculture and mixture in phosphorus-limited soil with homogeneous or heterogeneous supply patterns and inorganic (Pinorg) or organic phosphorus (Porg) forms.Results: In homogeneous Pinorg and Porg environments, XY335 had higher root length and surface area, but lower mycorrhizal colonization and the acid phosphatase and phytase activities in the rhizosphere, than HMY. In heterogeneous phosphorus environments, XY335 had higher root proliferation than HMY. The root trait divergence influenced the competition in mixture: XY335 had a competitive advantage compared to HMY under heterogeneous phosphorus conditions, whereas HMY exhibited a stronger competitive ability in homogeneous phosphorus treatments; these reverse trends were more significant in the Porg than Pinorg treatments.Conclusions: The results suggested the importance of root physiological traits in homogeneous phosphorus-limited soil environments, whereas P acquisition strategy based on root morphological traits favours heterogeneous phosphorus supply. [ABSTRACT FROM AUTHOR]

Abstract The suitable phytomanaging of mine tailings not only requires an improvement of soil fertility but also the assessment of the biotic interactions between the selected plant species. This study aimed to evaluate the effect of an organic amendment on the response of two plant species of contrasting habit, a tree, Pinus halepensis and a grass, Piptatherum miliaceum growing on a metal(loid)-contaminated substrate collected from mine tailings. Pots containing single plant individuals or their combination, with and without organic amendment (at 10% rate), were established and grown in a greenhouse for 13 months. Plant biomass, foliar ionome, leaf δ15N and metal(loid) concentrations were measured at the end of the experiment. The amendment alleviated P deficiency in the substrate and strongly stimulated biomass production by both plant species (10-fold for pine; 90-fold for the grass), leading to more balanced N/P ratios in leaves (especially for the grass). Co-culture with the grass negatively affected pine growth, decreasing total biomass and leaf δ15N values and inducing severe N deficiency (leaf N/P ratio<10). In contrast, co-culture with pine improved the nutrient status and growth of the grass, but only under non-amended conditions. Needle metal(loid) concentrations in P. halepensis were affected by both amendment addition and co-culture with the grass. High biomass growth with low metal(loid) concentrations in P. miliaceum leaves for the amended treatment makes this grass species suitable for the phytomanagement of metal(loid) polluted tailings, since it achieves high biomass production together with low concentrations of metal(loid)s in edible/senescent parts. Highlights • Co-culture modulated plant performance in amended treatments. • Co-culture with the grass P.miliaceum negatively affected pine (P.halepensis) growth. • P.miliaceum showed higher competitive ability when co-cultured with P.halepensis. [ABSTRACT FROM AUTHOR]

Abstract Point process statistics provides valuable tools for many ecological studies, where 'points' are commonly determined to represent the locations of plants or animals and 'marks' are additional items such as species or size. In the statistical analysis of marked point patterns, various correlation functions are used such as the mark variogram or the mark correlation function. Often the interpretation of these functions is not easy and the non-spatial ecologist is in need of support. In order to make the analysis of spatial point patterns more accessible to ecologists, we introduced and tested a new graphical method, the mark-mark scatterplot. This plot visualises the marks of point pairs of inter-point distances r smaller than some small distance r max. We tested the application of the mark-mark scatterplot by reconsidering three quite different tree patterns: a pattern of longleaf pine trees from the southern US which was strongly influenced by fires, a tropical tree pattern of the species Shorea congestiflora from Sri Lanka and a Scots pine pattern from Siberia (Russia). The new method yielded previously undetected cause-effect information on mark behaviour at short inter-point distances and thus improved the analysis with mark correlation functions as well as complemented the information they provided. We discovered important new correlations in clusters of trees at close proximity. The application of the mark-mark scatterplot will facilitate the interpretation of point process summary statistics and will make point process analysis more accessible to ecologists not specialized in point process statistics. Highlights • The mark-mark scatterplot fills an important gap in preparing and interpreting the analysis of spatial point patterns. • We re-visited three published spatial data analyses and added significant new information. • The mark-mark scatterplot allows a more comprehensive understanding and validation of spatial analyses. • The new tool makes spatial summary statistics more intelligible and trustworthy for ecologists. [ABSTRACT FROM AUTHOR]

The sole and integrated effects of N rates and cropping patterns on grain yield advantage (a-c), and carbon emission efficiency advantage (d-f). Notes: CEE, the carbon emission efficiency; N1-150, N2-225, and N3-300 represented three N levels of 150, 225 and 300 kg ha−1, respectively. [Display omitted] • Soybean intercropped with wheat or maize promoted LER, showing plant facilitation. • Plant facilitation increased LER and reduced nitrogen application by increasing NUE. • Facilitation promoted carbon emission (CE) with C&N degradation enzyme activity. • Wheat-maize intercropping showed opposite trend due to interspecific competition. • Plant facilitation increased carbon emission efficiency (yield/CE) but lowered N application. It is critical to reduce carbon (C) emission and nitrogen (N) input in agroecosystems under a changing climate. If crop diversification is introduced, interspecific plant–plant interactions as an effective pathway may achieve this goal. However, the related process and its mechanism are poorly understood. A two-year field study was conducted to explore the effects of intercropping systems including soybean-maize, soybean- wheat and maize-wheat on the land equivalent ratio (LER), nitrogen use efficiency (NUE), seasonal carbon emission, and soil properties in a typical semiarid environment. Three N rates (N1: 150 kg ha−1, N2: 225 kg ha−1, N3: 300 kg ha−1) were applied. The result indicated that the intercropping with soybean significantly increased system productivity with LER > 1, showing a typical plant–plant facilitation. However, the LER of maize–wheat intercropping was significantly lower than 1, representing interspecific competition. With the increasing N rate, the productivity of monoculture wheat or maize was evidently promoted. Particularly, the productivity under N2 and N3 remained at a similar level due to interspecific facilitation. This trend was mechanically driven by the improved N uptake (NLER > 1) and NUE under the presence of interspecific facilitation. Critically, interspecific facilitation was observed to promote carbon emissions (CE) by 4.0%-6.3%, since root input, microbial activities and the C&N decomposition enzyme activities were significantly enhanced. To say, interspecific facilitation evidently enhanced carbon emission efficiency (Yield/CE) whereas interspecific competition turned to lower it. To sum up, plant facilitation improved crop productivity and carbon emission efficiency by reducing N input. Our findings provided a new insight into the exploration of green solution in terms of reducing emissions and increasing efficiency, as well as lowering N fertilizer application in the natural and agricultural ecosystems. [ABSTRACT FROM AUTHOR]

Given the growing interest in ecological intensification directed towards sustainable crop production, a study was conducted to assess the biological and production response of pea intercropped with spring wheat or linseed under various growing conditions. The experiment was conducted in 2009–2011 on a Haplic Phaeozem soil in the western part of Poland. Intercropping of pea significantly reduced the green area index and the normalized difference vegetation index values, but growing pea with linseed caused a significant increase in the number of nodes with pods, pods per stem, and seeds per stem. Intercropping with wheat increased the seed number per pod. Seed inoculation with Nitragina significantly increased the number of pea pods and seeds per stem. Wheat intercropped with pea, with inoculation and foliar fertilization, attained significantly lower straw weight and spike length. Intercropping of linseed significantly reduced the features of the yield structure. Bacterial inoculation increased the production potential of pea at the expense of the supporting plants.

Entomopathogenic fungi from the genus Beauveria (Vuillemin) play an important role in controlling insect populations and have been increasingly utilized for the biological control of insect pests. Various studies have reported that Beauveria bassiana (Bals.), Vuill. also has the ability to colonize a broad range of plant hosts as endophytes without causing disease but while still maintaining the capacity to infect insects. Beauveria is often applied as an inundative spore application, but little research has considered how plant colonization may alter the ability to persist in the environment. The aim of this study was to investigate potential interactions between B. bassiana and Zea mays L. (maize) in the rhizosphere following inoculation, in order to understand the factors that may affect environmental persistence of the fungi. The hypothesis was that different isolates of B. bassiana have the ability to colonize maize roots and/or rhizosphere soil, resulting in effects to the plant microbiome. To test this hypothesis, a two-step nested PCR protocol was developed to find and amplify Beauveria in planta or in soil; based on the translation elongation factor 1-alpha (ef1α) gene. The nested protocol was also designed to enable Beauveria species differentiation by sequence analysis. The impact of three selected B. bassiana isolates applied topically to roots on the rhizosphere soil community structure and function were consequently assessed using denaturing gradient gel electrophoresis (DGGE) and MicroRespTM techniques. The microbial community structure and function were not significantly affected by the presence of the isolates, however, retention of the inocula in the rhizosphere at 30 days after inoculation was enhanced when plants were subjected to intensive wounding of foliage to crudely simulate herbivory. The plant defense response likely changed under wound stress resulting in the apparent recruitment of Beauveria in the rhizosphere, which may be an indirect defensive strategy against herbivory and/or the result of induced systemic susceptibility in maize enabling plant colonization.

Root competition for below-ground resources between edible plants may provide for long-term sustainability of agriculture systems. Intercropping can be more productive than a pure crop due to taking advantage of the morphological differences between species. In pure cropping, all biophysical interactions between plants occur through soil conditions. In intercropping, competition for water and nutrients is of major importance, but if the roots of one species occupy the zone just underneath the roots of the other crop, they can better use the resources of the root zone of the crop. The root system demonstrates a high degree of plasticity in its development in response to local heterogeneity of the soil profile and plant density. This study aimed at determining: (i) the morphological characteristics of the root systems of linseed, pea and vetch depending on the method of sowing; (ii) the root distribution in various soil types and at different soil profile depths (0–15 cm, 15–30 cm). Two three-year field experiments were conducted on two soil types in south Poland: soil A – Luvic Phaeozem (s1) and soil B – Eutric Cambisol (s2). These results show that linseed was more aggressive toward both legumes in mixture, but it produced lower yield compared to pure cropping. The environmental stress of plants in mixtures increased the relative weight of roots, which resulted in decreasing the root-shoot ratio (RSR).

Bioaccumulation of heavy metals can be affected by various crop-weed interactions in agroecosystems. An experiment was conducted to evaluate the role of belowground interaction of soybean and purslane (Portulaca oleracea L.) weed on cadmium (Cd) uptake and its allocation to soybean grains. The experimental treatments included two cropping systems (mono and mixed culture), two salinity levels (0% and 0.5% NaCl) and three levels of Cd in soil (control; 3 and 6 mg Cd/kg). Results showed that the promoting effect of salinity on Cd uptake by soybean and Cd allocation to grains was enhanced in the presence of purslane compared to the absence of neighbour plant. This could be due to increasing Cd-mobilization within the shared rhizosphere of plants. In the non-saline soil decreasing uptake and grain allocation of Cd in co-planted soybean was associated with enhancing of purslane Cd uptake and the depletion of Cd in soil solution. Therefore, it can be concluded that co-planted purslane can alter the uptake of cadmium to the neighboring soybean plants; its effect may be influenced by soil environmental conditions such as salinity.

Understanding how ecological networks are organised over the course of an organism’s lifetime is crucial for predicting the dynamics of interacting populations and communities across temporal scales. However, most studies so far considered only one life history stage at a time, such as adult, when studying networks of interacting species. Therefore, knowledge about how multiple life history stages affect the development and stability of plant–plant association networks is lacking. We measured the understory adult plant community and the soil seed bank across a plant age gradient of the nurse shrub Retama sphaerocarpa in an arid ecosystem in Spain. Using a multilayer network approach, we built adult understory–nurse and seed bank–nurse networks and analysed how network nestedness, species’ role, and species specificity varied between them and with nurse plant age. We found that seed bank and adult understory networks changed depending on nurse plant age in two different ways. With increasing nurse plant age, adult understory networks became significantly more nested than seed bank networks. The nested architecture of seed bank networks was therefore a poor predictor of adult understory network nestedness. The contribution and specificity of species to network nestedness increased with increasing nurse plant age more in the adult understory than in seed bank networks, despite high species turnover. Our data show that life history and ontogeny affect the development of plant–plant association networks. Niche construction and environmental filtering along nurse ontogeny seem pivotal mechanisms structuring adult understory networks while the assembly of seed bank networks seems rather stochastic. We highlight the importance of mature plant communities for maintaining rare species populations and supporting the stability of ecological communities through time. [ABSTRACT FROM AUTHOR]

Given the growing interest in ecological intensification directed towards sustainable crop production, a study was conducted to assess the biological and production response of pea intercropped with spring wheat or linseed under various growing conditions. The experiment was conducted in 2009-2011 on a Haplic Phaeozem soil in the western part of Poland. Intercropping of pea significantly reduced the green area index and the normalized difference vegetation index values, but growing pea with linseed caused a significant increase in the number of nodes with pods, pods per stem, and seeds per stem. Intercropping with wheat increased the seed number per pod. Seed inoculation with Nitragina significantly increased the number of pea pods and seeds per stem. Wheat intercropped with pea, with inoculation and foliar fertilization, attained significantly lower straw weight and spike length. Intercropping of linseed significantly reduced the features of the yield structure. Bacterial inoculation increased the production potential of pea at the expense of the supporting plants. [ABSTRACT FROM AUTHOR]