Relative Competition Intensity Research Articles

Videoconferencing continuance and business trip reduction in the post-pandemic age

Videoconferencing (VC) software was widely adopted by organizations during the COVID-19 pandemic to maintain business communication during the suspension of business travel. In the post-pandemic age, will organizations continue to use VC software, and how will VC continuance influence the number of business trips? We conceptualize business travel as a communication problem and conduct an empirical study to investigate the use of VC during the COVID-19 pandemic and its impact on future business travel. We identify the technology–organization–environment framework as a theoretical tool to guide our research design. Using a sample of business managers in Hong Kong and the United States and the seemingly unrelated regression methodology, we identify the relative advantage, top management, and competition intensity factors that support VC continuance and business trip reduction in the post-pandemic age. This study enhances research on information systems continuance and provides practical implications for business trip planning.

Sexual competition and light regimes interactively affect dimorphism and competitiveness of opposite sexes in Populus yunnanensis

Light, as the most important energy and environmental signal, exerts crucial impacts on plant-plant interactions and the composition of plant communities. However, little attention has been paid to understanding how females and males respond to sexual competition under different light conditions. In this study, we investigated morphological and physiological parameters between two sexes of Populus yunnanensis under intra- and intersexual competition in two light regimes, i.e., full light and shading conditions (equal to 55% full light). Under full-light conditions, males grown under intersexual competition exhibited greater above-ground biomass accumulation, specific leaf area (SLA), root-to-shoot ratio (R/S), non-structural carbohydrate (NSC) utilization efficiency, and a higher ability to maintain the balance of nitrogen (N) and phosphorus (P) content compared to females. These eco-physiological responses confer males with a competitive advantage over females under sufficient light conditions. In contrast, there were no significant sex-specific differences in biomass accumulation and relative competitive intensity (RCI) values under shade treatment. Under shading, the opposite sexes of P. yunnanensis exhibited mutual suppression of each other to varying degrees, showing similar competitive potential. These results demonstrate that the performance of plants in terms of morphology and physiology is strongly affected by patterns of sexual competition and light regimes. The asymmetry in sexual competition might be a crucial factor influencing the biased sex ratio of P. yunnanensis in natural habitats.

Cool semi‐arid cropping treatments alter Avena fatua's performance and competitive intensity

AbstractIntroductionMultiple herbicide‐resistant Avena fatua L. is common in the Northern Great Plains, USA. This prevalence and the ecological impacts of tillage in this semi‐arid agricultural region have created a need for integrated weed management, with a specific knowledge gap in using annual forage crops and targeted grazing for A. fatua suppression.Materials and MethodsA 2‐year study in central Montana, USA, assessed A. fatua performance (aboveground biomass, stem density and seed production) in response to seven cropping treatments: (1–4) tall and short spring wheat cultivars crossed with high and low seeding rates, (5–6) annual forage mixture terminated using sheep grazing and simulated haying and (7) tilled fallow. Avena fatua's competitive intensity in wheat and the annual forage mixture was determined using a relative competition intensity index.ResultsAvena fatua performance was lowest in tilled fallow, although stem density and seed production did not differ from the grazed annual forage treatment. Response variables were lower in the forage treatments compared with the wheat treatments, and there were no differences among the four fully crossed wheat treatments. Separate analysis of the wheat treatments indicated lower A. fatua biomass and stem density when wheat was sown at a higher rate with no impact of wheat height. Avena fatua competition impacted wheat and forage crops but was more intense for wheat.ConclusionTillage was the most effective treatment at reducing A. fatua performance, but annual forage mixtures can be used to resist A. fatua invasion (reduced A. fatua competitive intensity) and limit its performance after invasion. We conclude that crop sequences that combine higher cash crop (wheat) seeding rates and competitive annual forage mixtures may be utilized to manage A. fatua invaded systems, thereby reducing heavy reliance on tillage in the US Northern Great Plains and similar semi‐arid regions.

The interspecific competition of tree plants in the presence of AM fungi and litter facilitates root morphological development and nutrition when compared with intraspecific competition.

Arbuscular mycorrhizal (AM) fungi can affect plant growth by regulating competition. Nutrient-deficient karst habitats contain abundant plants that compete for nutrients through interspecific or intraspecific competition, involving the nutritional transformation of litter decomposition. However, how plant competition in the presence of AM fungi and litter affects root development and nutrition remains unclear. A potted experiment was conducted, including AM fungus treatment with or without Glomus etunicatum, the competition treatment concerning intraspecific or interspecific competition through planting Broussonetia papyrifera and Carpinus pubescens seedlings, and the litter treatment with or without the mixture of B. papyrifera and C. pubescens litter leaves. The root morphological traits were analyzed, and nitrogen (N), phosphorus (P), and potassium (K) were measured. The results showed that AM fungus differently affected the root morphological development and nutrition of both competitive plants, significantly promoting B. papyrifera roots in the increase of dry weight, length, volume, surface area, tips, and branches as well as N, P, and K acquisitions regardless of litter addition. However, there was no apparent influence for C. pubescens roots, except for the diameter in the interspecific competition with litter. The root dry weight, length, volume, surface area, and tips of B. papyrifera under two competitive styles were significantly greater than C. pubescens regulated by AM fungus, presenting significant species differences. The responses of the relative competition intensity (RCI) on root morphological and nutritional traits indicated that AM fungus and litter both asymmetrically alleviated more competitive pressure for B. papyrifera than C. pubescens, and the interspecific competition facilitated more root morphological development and nutrition utilization by endowing B. papyrifera root superiority relative to C. pubescens compared with the intraspecific competition. In conclusion, interspecific competition is more beneficial for plant root development and nutrition than intraspecific competition in the presence of AM fungus and litter via asymmetrically alleviating competitive pressure for different plants.

High interspecific competitiveness of the invasive plant Xanthium italicum Moretti severely reduces the yield and quality of Carthamus tinctorius L.

Safflower is an annual herb of Compositae, which has great economic value. To explore the impact of invasive weed Xanthium italicum Moretti on the economic crop safflower, field experiments were conducted, the growth-related characters and the relative intensity of competition between the two species was explored. The results showed that under monoculture conditions, the stem height, crown width, stem diameter and the biomass of X. italicum root, stem and leaves were 1.14, 1.96, 1.82, 4.42, 4.21 and 3.99 times as high as those of safflower, respectively. When the two species coexisted, the growth related characters of X. italicum were further significantly improved, while the growth related characters of safflower were significantly decreased. When coexisted with X. italicum, the corolla biomass, hydroxysafflor yellow A content of corolla, seed yields, 100-seed weight, and seed oil content of safflower in the interplanted treatment 90.04%, 33.11%, 63.89%, 40.58%, and 25.61% lower than those in the monocultured treatment, respectively. Relative yield (RY) and Competitive balance index (CB) of X. italicum and safflower showed that the interspecific competitiveness of X. italicum was significantly higher than that of safflower. Under the competitive inhibition of X. italicum, not only the vegetative growth, but also the reproductive growth, yield, and quality of the economic organs of safflower were significantly negatively impacted. Together, our findings provide important scientific basis for evaluating the invasion risks and consequences of safflower’s cropland ecosystem by X. italicum.

Hyperspectral remote sensing to assess weed competitiveness in maize farmland ecosystems

Weed competition causes serious economic losses to maize production. Timely and accurate assessment of pressure from competition is crucial for ecological weed management. In this work, we apply hyperspectral remote sensing (HRS) technology to conduct a competitive experiment in Harbin, China, in 2021, with 5-leaf maize as the study target. A weed competition assessment method that combines comprehensive competition indices (CCI) and deep learning is proposed. For the comprehensive competition assessment, the relationship between different weed competitive pressures (Levels 1–5) and changes in the structural and physiological information of maize was analyzed. The accumulative/transient competition indices CCI-A and CCI-T were designed for accurate quantification. The results showed that parameters such as plant height, stalk thickness and nutrient elements of maize decreased with increasing competition level. Parameters, such as stomatal conductance and transpiration rate, showed a fluctuating change of increasing and then decreasing with increasing competition level. Compared with the traditional relative competitive intensity (RCI), the standard deviation of CCI is 0.303 and 0.499. The dispersion effect of CCI is better and more suitable for quantifying the competition response. HRS images combined with 3D-CNN model were then applied to reveal the spectral response to different weed competition pressures (Levels 1–5) and to make early predictions of weed competition. The first-order derivative showed that the spectral reflectance exhibited significant differences at 520–525 nm peak, 570–655 nm trough, and near 700 nm red edge. For hyperspectral spatial-spectral features, the 3D-CNN model is proposed for prediction of competing indices CCI. In addition, the VIP method is used to select the characteristic wavelengths. The 3D-CNN model achieves a prediction accuracy of RMSE = 0.106 and 0.152 using 13 feature bands, which can accurately quantify the subtle changes in competition indices. Overall, this study shows that the combination of CCI and deep learning can provide a multivariate and comprehensive assessment of weed competition pressure.

Rhizospheric Bacillus-Facilitated Effects on the Growth and Competitive Ability of the Invasive Plant Ageratina adenophora.

The rhizospheric microbial community affects the population establishment of invasive plants in introduced areas, among which Bacillus has numerous functions in promoting plant growth. This study isolated and enriched the Bacillus community in the rhizospheric soil of the invasive plant Ageratina adenophora and the native accompanying plant Rabdosia amethystoides. The effects of these rhizospheric Bacillus communities on the growth and competition of A. adenophora and R. amethystoides were evaluated in pot experiments. The results showed that the number and diversity of Bacillus in the rhizospheric soil of A. adenophora were higher than those of R. amethystoides (A. adenophora: 122 strains in soil, 16 Bacillus taxa; R. amethystoides: 88 strains in soil, 9 Bacillus taxa). After Bacillus inoculation of A. adenophora in a pot experiment, Bacillus idriensis, Bacillus toyonensis and Bacillus cereus were accumulated in the rhizospheric of A. adenophora, which significantly increased the nitrate nitrogen (NO3–-N) content in the soil and the total carbon and nitrogen concentrations in A. adenophora in the mixed treatment. The selective accumulation of Bacillus enhanced the competitive advantage of A. adenophora over the native accompanying plant; the corrected index of relative competition intensity of A. adenophora-inoculated Bacillus reached double that of the uninoculated treatment, and the growth of native plants was greatly suppressed under mixed planting. Our study confirmed that invasion of A. adenophora can lead to the accumulation of specific Bacillus taxa in the rhizospheric soil, which in turn can increase the competitive advantage of A. adenophora.

Agency or Wholesale? The Role of Retail Pass-Through

With the rapid growth of e-commerce, agency selling is currently gaining popularity among online retailers (e-tailers). Prior research implicitly abstracts away cross-brand pass-through under traditional wholesale selling (i.e., how the retail price of another brand adjusts to changes in a given brand’s wholesale price) and suggests that a shift to agency selling benefits e-tailers but harms suppliers. As an important counterweight to this result, we discover that an e-tailer’s choice regarding selling format is critically moderated by retail pass-through behavior. On the one hand, agency selling can improve channel efficiency compared with wholesale selling. On the other hand, the relative intensity of supplier competition between these two selling formats is ambiguous. We show that the existing result applies only for a nonnegative cross-brand pass-through rate (e.g., under linear demands); otherwise (e.g., under multiplicative or exponential demands), the opposite may hold. Interestingly, we find that the conflict over the preference of selling format may not arise, and that all channel members could be better off with wholesale selling. Compared with the case of Bertrand competition, the e-tailer is even more likely to adopt wholesale selling under Cournot competition. Finally, under agency selling with an endogenous commission fee, we advise caution regarding the seemingly innocuous normalization of suppliers’ marginal costs. Surprisingly, suppliers may benefit from higher marginal costs. Overall, our findings not only shed light on the theory of agency selling but also provide a plausible explanation for the observation that wholesale selling continues to prevail in online markets. This paper was accepted by Eric Anderson, marketing.

Drought may be beneficial to the competitive advantage of Amaranthus spinosus

Abstract Drought can affect the growth and soil enzyme activities of invasive alien plants (IAPs). It is imperative to evaluate the competitive advantage of IAPs compared with that of the native species and the activities of soil enzymes under drought. This study aimed to evaluate the competitive advantage of the IAP Amaranthus spinosus that originated from tropical America compared with the native Chinese species A. tricolor and the activities of soil enzymes under drought. A competitive co-culture of A. spinosus and A. tricolor was established using a planting basin experiment. The two species were treated with different levels of drought, i.e. (i) the control; (ii) a light level of drought and (iii) a heavy level of drought. The functional traits, osmotic adjustment and the activities of antioxidant enzymes of the two species, as well as soil pH and electrical conductivity, contents of soil microbial biomass carbon and the activities of soil enzymes were determined. The relative competition intensity and relative dominance of A. spinosus were greater than those of A. tricolor under drought. Drought may provide an advantage to the competitive advantage of A. spinosus. Soil water-soluble salt content and sucrose hydrolytic power of A. spinosus were greater than those of A. tricolor under drought. The ability of A. spinosus to grow in soil with higher levels of water-soluble salt contents and sucrose hydrolytic power under drought may aid in its acquisition and utilization of nutrients.

Effects of Soil Heterogeneity and Species on Plant Interactions

Plant interactions are central in driving the composition and structure of plant populations and communities. Soil heterogeneity and species identity can modulate such interactions, yet require more studies. Thus, a manipulative experiment was done where three soil heterogeneity levels were developed by mixing local soil and sand in three different ratios (i.e., soil:sand ratio = 2:8, 5:5, and 8:2), and three typical species (i.e., Festuca elata, Bromus inermis, and Elymus breviaristatus) were used in different combinations. Soil heterogeneity was assumed to affect plant interactions, which were in turn modified by species. Plant height was applied as an indicator for plant interactions. Relative competition intensity (RCI) was used to quantify plant interactions, where RCI was applied as a ratio of monoculture and mixture performance. Results showed that soil heterogeneity and soil heterogeneity × species significantly affected the RCI in mixtures compared with plant individuals growing alone (i.e., RCI1). However, species as a single factor did not affect RCI1. Moreover, species and soil heterogeneity × species significantly affected the RCI in mixtures compared with two individuals growing together (i.e., RCI2), and the difference between RCI1 and RCI2 (i.e., RCIdiff). Soil heterogeneity significantly affected RCI2 of F. elata. This study suggests that soil heterogeneity could buffer the stability of plant populations by modifying plant interactions, which would subsequently drive plant establishment. To explore the underlying mechanisms of such patterns, further studies considering more species and plant traits are needed.

Soil Water Availability Changes in Amount and Timing Favor the Growth and Competitiveness of Grass Than a Co-dominant Legume in Their Mixtures.

The grasslands on the semi-arid Loess Plateau of China are expected to be particularly responsive to the size and frequency changes of extreme precipitation events because their ecological processes are largely driven by distinct soil moisture pulses. However, the plant growth and competitiveness of co-dominant species in response to the changes in the amount and timing of soil water are still unclear. Thus, two co-dominant species, Bothriochloa ischaemum and Lespedeza davurica, were grown in seven mixture ratios under three watering regimes [80 ± 5% pot soil capacity (FC) (high watering), 60 ± 5% FC (moderate watering), and 40 ± 5% FC (low watering)] in a pot experiment. The soil water contents were rapidly improved from low to moderate water and from moderate to high water, respectively, at the heading, flowering, and maturity stages of B. ischaemum, and were maintained until the end of the growing season of each species. The biomass production of both species increased significantly with the increased soil water contents, particularly at the heading and flowering periods, with a more pronounced increase in B. ischaemum in the mixtures. The root/shoot ratio of both species was decreased when the soil water availability increased at the heading or flowering periods. The total biomass production, water use efficiency (WUE), and relative yield total (RYT) increased gradually with the increase of B. ischaemum in the mixtures. The relative competition intensity was below zero in B. ischaemum, and above zero in L. davurica. The competitive balance index calculated for B. ischaemum was increased with the increase of the soil water contents. Bothriochloa ischaemum responded more positively to the periodical increase in soil water availability than L. davurica, indicating that the abundance of B. ischaemum could increase in relatively wet seasons or plenty-rainfall periods. In addition, the mixture ratio of 10:2 (B. ischaemum to L. davurica) was the most compatible combination for the improved biomass production, WUE, and RYTs across all soil water treatments.

Effects of nitrogen regulation and strip intercropping on faba bean biomass, nitrogen accumulation and distribution, and interspecific interactions

AbstractEffects of nitrogen fertilization on the accumulation and distribution of biomass and plant nitrogen content in intercropped faba beans, together with its impact on the interspecific interactions between faba bean and wheat has not been well studied. Here, we have used a logistic model to analyze the cropping systems (i.e., monocropped faba bean, monocropped wheat, and faba bean intercropped with wheat) by evaluating the effects of different levels of nitrogen application on the dynamic changes in biomass and nitrogen accumulation, along with the interspecific interaction. Using monocropped and intercropped faba beans in field experiments spanning two years, we found that nitrogen application increased both monocropped and intercropped faba bean yields. The yield of intercropped faba beans was greatest at the lower nitrogen input for two consecutive years. Nitrogen application increased the biomass and nitrogen accumulation in both monocropped and intercropped faba beans. The simulation parameters that increased were maximum nitrogen accumulation (A') and maximum accumulation rate (R'max) while the initial cumulative rate (r') decreased. Compared with monocropping, intercropped faba bean–wheat showed increased yield and biomass accumulation, along with a significantly increased initial growth rate (r) and a maximum instantaneous growth rate (Rmax). Intercropping reduced stem and leaf biomass and the nitrogen distribution ratio while increasing the pod content. In the early intercropped faba bean growth stage, there was no competition for nutrients or any kind of yield advantage, while in the later stages, the nutrient competitiveness of intercropping was stronger than the intraspecific competition, showing the advantages of intercropping on biomass and yield (i.e., relative crowding coefficient [K] >1, relative interspecific competitiveness [RC] >0, and relative competition intensity [RCI] <0). In summary, nitrogen application of 45 kg ha–1 could be the desired amount that maximizes the nutrient competition and interspecific advantages in the middle and late stages of faba bean growth when intercropped, thus contributing to the yield.

Nitrogen Uptake, Not Transfer of Carbon and Nitrogen by CMN, Explains the Effect of AMF on the Competitive Interactions Between Flaveria bidentis and Native Species

Rhizophagus intraradices, one of the common arbuscular mycorrhizal fungi (AMF) grown in the roots ofFlaveria bidentis, facilitates the invasion of this exotic plant species into China. However, it is still unknown whether nutrient transfer through the common mycorrhizal networks (CMN) between this exotic species and the native species enhances the competitive growth ofF. bidentisover the native species. To elucidate this question and the related mechanism, an isotopic labeling technique was used to test the transfer of carbon (C) and nitrogen (N) by CMN. Native species likeSetaria viridisandEclipta prostratawere selected to compete withF. bidentisin a polyvinyl chloride (PVC) box. Two competitive groups (F. bidentis-S. viridisandF. bidentis-E. prostrata), three treatments (monoculture ofF. bidentis, the mixture ofF. bidentisand the native plant, and the monoculture of the native plant), and two levels of AMF (presence or absence) were assigned. Results showed that the corrected index of relative competition intensity (CRCI) ofF. bidentisin the presence of AMF < 0 suggests that the competition facilitated the growth ofF. bidentiswith eitherS. viridisorE. prostrata. The reason was that the inoculation ofR. intra radicessignificantly increased the C and N contents ofF. bidentisin the mixtures. However, the effects ofR. intra radiceson the two native species were different: negative effect on the growth ofS. viridisand positive effect on the growth ofE. prostrata. The change of N content inS. viridisorE. prostratawas consistent with the variation of the biomass, suggesting that the N uptake explains the effects ofR. intraradiceson the competitive interactions betweenF. bidentisand the two native species. Moreover, the transfer of C and NviaAMF hyphal links did occur betweenF. bidentisand the native species. However, the transfer of C and N by the CMN was not positively related to the competitive growth ofF. bidentis.

Waterlogging tolerance of the invasive plant Aegilops tauschii translates to increased competitiveness compared to Triticum aestivum

In the cultivation of wheat (Triticum aestivum L.), waterlogging has been identified as one of the most important limiting factors. It affects the overall global wheat production as well as that for the People’s Republic of China. Aegilops tauschii Coss., so far known as the main malignant weed in the wheat fields but it is unclear whether its invasiveness and competition with wheat would be affected by waterlogging. To study this, we conducted a controlled pot experiment using the De Wit replacement method. Monocultured and mixed experimental setups of A. tauschii and wheat were performed to study the effects of 0 (control), 5, 10, 15, 20 and 25 days of water stress treatments on A. tauschii growth and its competition with wheat. The results showed that in terms of morphological characteristics, the height increase of A. tauschii plants showed strong water tolerance. While the leaf area and total biomass were significantly affected by water flooding stress. In terms of physiological characteristics, A. tauschii exhibited high superoxide dismutase (SOD) activity, which promptly removed active oxygen free radicals generated by water flooding stress. This activity reduced the accumulation of thiobarbituric acid (TBARS) in the plant, and thus exhibited stronger water tolerance than wheat. In addition, regarding phenotypic plasticity, the mean plasticity index (PI) values of most morphological and physiological parameters of A. tauschii were close to those of wheat. Yet the PI values of plant height and root biomass were significantly higher than those of wheat. It indicates that the waterlogging tolerance to A. tauschii may be related to the high values of some particular traits. Finally, with the prolonged waterlogging treating time, the relative yield (RY) value of A. tauschii was always greater than 1, while for wheat, the RY value was less than 1. In addition, the competitive balance (CB) value of A. tauschii was greater than 0 and its relative competitive intensity (RCI) was less than 0. This shows that the short-term waterlogging stress changed the competition relationship between A. tauschii and wheat. In it wheat was suppressed and the competitiveness of A. tauschii was enhanced. In summary, A. tauschii have a certain degree of tolerance to waterlogging, and short-term waterlogging would promote its competition with wheat, which is expected to increase its invasion potential.

The Nutrient Status of Plant Roots Reveals Competition Intensities in Rubber Agroforestry Systems

Controversial competition theories may confuse the current understanding of belowground plant competition and thus result in incorrect diagnoses and mitigation strategies for nutrient competition. As such, the management of nutrient competition is a major challenge in the application and development of rubber agroforestry systems (AFSs). To explore the effects of plant competition on the nutrient status of rubber AFSs, this study measured the carbon, nitrogen, and phosphorus concentrations of the litter and soil and in plant leaves, stems, and roots from five rubber plantations (i.e., rubber monocultures and rubber mixed with cocoa, coffee, tea, and Flemingia macrophylla (Willd.) Merr., 1910)). The relative competition intensity indexes were calculated to evaluate the competition intensity of each mixed-species system, and Bayesian networks were established to investigate the linkage effects of interspecific competition for nutrients. This study demonstrated that rubber trees had weak competition with cocoa trees, moderate competition with F. macrophylla and tea trees, and intense competition with coffee trees. With the increase in competition intensity, the negative effects of interspecific competition on soil gradually offset the improvement in soil nutrients achieved with intercropping. Nitrogen and phosphorous translocation from the stems to the roots was enhanced by competition. However, enhanced nutrient allocation to roots may have led to insufficient nitrogen and phosphorous supplies in plant leaves. The quality of the litter therefore decreased because the nutrient status of fallen leaves determines the initial litter conditions. Such consequences may reduce the release of nutrients from the litter to the soil and thus increase soil nutrient depletion. This study revealed that competition effects were most obvious for the root nutrient status, followed by the stem and leaf nutrient statuses. Moreover, this study further demonstrated that the nutrient concentration of plant roots can better indicate the intensity of nutrient competition than the nutrient concentration of other plant organs.

Impact of Pricing Practice Management on Performance and Sustainability of Supermarkets in the Urban Area of Enugu State, Nigeria

Consumer shopping behavior is becoming increasingly polarized, which has an impact on price decisions, and the performance and sustainability of supermarkets. This study sets out to empirically determine the impact that pricing practice management has on the performance and sustainability of supermarkets in the urban area of Enugu State, Nigeria. The study explicitly attempts to ascertain the impact of value-informed pricing practice, competition-informed pricing practice, and cost-informed pricing practice on supermarkets’ performance and sustainability in urban Enugu. The paper also examines the impact of adopting three different pricing practices when the relative product advantage and/or competitive intensity are/is moderating variable(s). With a population of 100 supermarkets, 48 responded to the questionnaire. A multiple regression analysis was utilized to test the hypothesis formulated for the study. The study found that the adoption of a value-informed pricing practice, competition-informed pricing practice, and cost-informed pricing practice by management has no significant impact, negatively significant impact, and positively significant impact, respectively, on supermarkets’ performance and sustainability in urban Enugu. The study also found that the impact of the three pricing practices on performance and sustainability of supermarkets in the urban area of Enugu State, changes significantly when relative product advantage and/or competitive intensity are/is moderating variable(s). Amongst others, this study recommends that the management of supermarkets should carry out an internal and external environmental assessment of a product before deciding on the appropriate pricing practice to adopt for that product. Critical consideration should be given to the relative product advantage and the competitive intensity of the product. Moreover, the adopted pricing practice must be situated within the overall performance objective of the firm in such a way that resources are optimized, and the maximum value attained.

Agency or Wholesale? The Role of Retail Pass-Through

With the rapid growth of e-commerce, agency selling is currently gaining popularity among online retailers (e-tailers). Prior research implicitly abstracts away cross-brand pass-through under traditional wholesale selling (i.e., how the retail price of another brand adjusts to changes in a given brand's wholesale price) and suggests that a shift to agency selling benefits e-tailers but harms suppliers. As an important counterweight to this result, we discover that an e-tailer's choice regarding selling format is critically moderated by retail pass-through behavior. On the one hand, agency selling can improve channel efficiency compared to wholesale selling. On the other hand, the relative intensity of supplier competition between these two selling formats is ambiguous. We show that the existing result applies only for a nonnegative cross-brand pass-through rate (e.g., under linear demands); otherwise (e.g., under multiplicative or exponential demands), the opposite may hold. Interestingly, we find that the conflict over the preference of selling format may not arise, and that all channel members could be better off with wholesale selling. Compared to the case of Bertrand competition, the e-tailer is even more likely to adopt wholesale selling under Cournot competition. Finally, under agency selling with an endogenous commission fee, we advise caution regarding the seemingly innocuous normalization of suppliers' marginal costs. Surprisingly, suppliers may benefit from higher marginal costs. Overall, our findings not only shed light on the theory of agency selling but also provide a plausible explanation for the observation that wholesale selling continues to prevail in online markets.

Plant-plant interactions and resource dynamics of Abies fabri and Picea brachytyla as affected by phosphorus fertilization

Although extensive research has been conducted on the temporal dynamics of plant-plant interactions, little is known about the effect of phosphorus (P) availability. In this study, Abies fabri and Picea brachytyla seedlings were collected from the late-stage Hailuogou glacier retreat area and grown under different P regimes (control and P fertilization) from year 2015 to 2016 in a common garden experiment to investigate whether plant-plant interactions are modulated by P availability. We found that P fertilization affected the relative competition intensity (RCI). Under control conditions in 2015, the growth of A. fabri was facilitated by the presence of P. brachytyla. Under P fertilization, the facilitative effect was more intensive: the leaf, stem and total biomass of A. fabri significantly increased under interspecific interaction compared with intraspecific interaction, but no effect was found in P. brachytyla. RCI showed similar tendencies both in 2015 and 2016. In addition, plant-plant interactions and P fertilization caused temporal variation in C, N, P and non-structural carbohydrate (NSC) contents. The growth of A. fabri greatly benefited from the presence of P. brachytyla when exposed to P fertilization and showed higher biomass, and C, N, P and NSC accumulations. Our results demonstrated interactive effects between environmental conditions (i.e. P availability) and plant-plant interactions that are closely related to resource accumulation.

Silver nanoparticles reduced the invasiveness of redroot pigweed.

The differences in the growth performance between invasive species and native species might paly a key role in the effective invasion. The extensive use of silver nanoparticles (AgNPs) has created the concern of their release into environment. Thus, the possible effects of AgNPs on the growth performance of invading agents are critical to better illustrate the underlying mechanisms for effective invasion. This study aimed to assess the impacts of AgNPs with different concentrations [200 and 400 mg kg (soil)-1] and particle sizes (30 and 70 nm) on the growth performance and competitive ability of well known invasive Amaranthus retroflexus L. (redroot pigweed) and native A. tricolor L. (red amaranth). It was observed that the growth characteristics and supporting ability of redroot pigweed were significantly lower than those of amaranth. Results of the relative competitive intensity index and the relative dominance index also revealed that redroot pigweed exhibited lower competitive ability compared to red amaranth, especially under AgNPs. It can be assumed that the poor growth performance and competitive ability of redroot pigweed might prevent its invasiveness under AgNPs. The supporting ability, leaf photosynthetic area, leaf growing ability, leaf resource use efficiency and acquisition capability, and growth competitiveness of the two plant species were found to be significantly reduced under AgNPs. AgNPs with 30 nm at 400 mg kg (soil)-1 triggered more toxicity on the supporting ability and growth competitiveness of the two plant species than AgNPs with 30 nm at 200 mg kg (soil)-1. In addition, AgNPs with 30 nm imparted high toxicity on the leaf growing ability of red amaranth than AgNPs with 70 nm. However, the particle size of AgNPs did not address significant effects on the growth performance of redroot pigweed. Ag+ solution exhibited stronger toxicity on the supporting ability and leaf growing ability of the two plant species than AgNPs.

Increasing soil age drives shifts in plant-plant interactions from positive to negative and affects primary succession dynamics in a subalpine glacier forefield

The stress gradient hypothesis predicts that plant-plant interactions switch between facilitation (positive) and competition (negative) along environmental gradients, with facilitation being more common under high abiotic stress conditions relative to more moderate abiotic stress conditions. Our aim was to reveal, whether the interactions between Populus purdomii Rehder and Salix rehderiana Schneider switch from positive to negative during the early stages of primary succession in the Gongga Mountain glacier retreat region. We also investigated, whether soil age is a major driving factor for the transformation of interactions between neighboring plants. We analyzed differences between intraspecific interactions and interspecific interactions of Populus and Salix under 20- and 40-year-old soil conditions, including plant biomass accumulation and allocation, nutrient absorption and utilization, relative competition intensity, non-structural carbohydrates, foliar carbon and nitrogen isotope composition, mesophyll cell ultrastructure, soil microbial biomass and community structure, extracellular enzyme activities, and soil organic carbon (SOC), soil total nitrogen (TN), soil ammonium (NH4+-N), and soil nitrate (NO3−-N) contents. We found that P. purdomii and S. rehderiana growing under interspecific interactions had greater contents of aboveground dry matter, belowground dry matter and total dry matter compared to intraspecific interactions in 20-year-old soil. Furthermore, in 40-year-old soil conditions, the phospholipid fatty acid (PLFA) analysis showed that Populus and Salix exposed to interspecific interactions exhibited lower amounts of gram-positive bacteria, fungi (18,1 ω9c) and actinomycetes, and lower levels of total PLFAs than those growing under intraspecific interactions. The redundancy analysis (RDA) results demonstrated that soil N was the most important parameter contributing to the composition of microbial communities. In addition, the 15N stable isotope labeling method showed that Populus and Salix growing under interspecific interactions had higher foliage δ15N derived from NO3− (δ15N-NO3−) than those growing under intraspecific interactions in 20-year-old soil. In summary, our results demonstrated that Populus-Salix interactions exhibited positive effects on survival in 20-year-old soil. Conversely, under 40-year-old soil conditions, Populus-Salix interactions presented negative effects in relation to nutrients and elimination by neighboring plants. Moreover, soil age is a major driving factor for plant-plant interactions that shift from positive to negative with an increasing soil age in the Gongga Mountain glacier forefield. In all, our results support the stress gradient hypothesis. Our findings improve understanding of plant-plant interactions and plant-soil feedbacks during the early stages of soil development, and of the construction of vegetation communities.