Plant Arrangement Research Articles

Evaluation of the optimization effect of a combined constructed wetland with micro-polluted water sources

The research aimed to evaluate the eight-years purification performance of a large-scale combined constructed wetland (CW) improving micro-polluted water, to analyze problems occurring during long term operation and their causes, as well as to propose measures and suggestions for further optimization. The results shows that the average removal rates (RRs) of permanganate index (CODMn), ammonia nitrogen (NH4+-N), total nitrogen (TN) and total phosphorus (TP) were 4.39 % ± 12.64 %, 41.57 % ± 16.36 %, 32.61 % ± 23.36 % and 47.05 % ± 20.39 % during 2013–2020, respectively. Compared with other similar constructed wetlands, the removal rate of each pollution indicator was relatively low. The deep purification zone exhibited the best performance due to the long hydraulic retention time (HRT); the pretreatment zone had low capacity in removal of CODMn and TN; the emergent plant zone was significantly affected by the plant arrangement; the purification performance of submerged plant zone in the first three years was inefficient due to the difficult restore of submerged plants. The average RRs for CODMn, NH4+-N, TN, and TP after the optimization engineering were 2.54 ± 14.76 %, 39.62 ± 18.47 %, 31.86 ± 22.19 %, and 46.06 ± 21.02 %, respectively, indicating that the overall purification performance was not improved significantly. The analysis shows that influent concentrations, temperature, HRT and design of combined processes were key factors influencing the purification performance of CW. In the future, it is necessary to take targeted measures for the above key factors to improve the water quantity and quality assurance rate of drinking water sources, to ensure the drinking water health and safety.

Effects of the twin-row planter with subsoiling on soybean growth and yield in northern China

Twin-row ridge cultivation is widely used in soybean planting in northern China. In order to find the optimal parameters of soybean agronomy, the twin-row planter with subsoiling was designed. Field experiments were conducted to evaluate the effects of plant arrangements and cluster densities on soybean growth and grain yield under different tillage treatments. The experiment used a randomised complete block design consisting of 20 treatments in a 2×2×5 factorial arrangement. Two tillage treatments were inter-row subsoiling and no subsoiling. Each tillage treatment included the combination of plant arrangements (side-by-side arrangement and triangular arrangement) and cluster densities (one, two, three, four, and five plants). The variables measured included soil moisture content, seedling emergence, biomass accumulation and allocation, and grain yield. We have concluded that the performance of inter-row subsoiling treatment was much better than that of no subsoiling treatment. Meanwhile, the triangular arrangement and two plants per cluster were the best choices for soybean biomass accumulation and grain yield in northern China. This study provided a reference for the innovative design of the twin-row planter with subsoiling and the optimisation of soybean agronomy.

EFECTO DE UN BIOESTIMULANTE EN EL RENDIMIENTO DE FORRAJE DE TRITICALE (x Triticosecale) EN SIEMBRA ESCALONADA ASOCIADA CON HABA (Vicia faba)

<p><strong>Background.</strong> The associations of poaceae and fabaceae forage species are important to provide cattle with a balanced diet between proteins and carbohydrates; also to contribute to the sustainable management of soils. <strong>Objective</strong>. The objective of the research was to determine the effect of the natural biostimulant on the triticale forage components during staggered sowing associated with faba bean. <strong>Methodology</strong>. The research was carried out under a randomized complete block experimental design with three repetitions. The genetic material was a line of semi-late triticale and a local variety of faba bean. Applications of a biostimulant were made in two phenological of the triticale stages forage during the staggered sowing (0, 20 and 40 days after sowing the bean). The variables evaluated were percentage increase of foliar N in triticale, biomass in triticale and broad bean, green forage yield of triticale and faba bean, presence of <em>Rhizobium</em> nodules in faba bean and interspecific competition indices of the associated system. <strong>Implications</strong>. The establishment of a triticale-faba bean association requires certain planting arrangements, varieties and nutrition to avoid the effects of competition, which cause the dominance or displacement of any of the species. <strong>Conclusions</strong>. The application of biostimulant in triticale in the tillering stage 20 days after sowing the bean, the highest yield of triticale forage was found, allowing the increase in the concentration of foliar nitrogen (1.8%) and rhizobial nodules per plant (175.83) of broad bean; higher biomass (6.49 t ha<sup>-1</sup>) in triticale and higher amount of total forage (39.02 t ha<sup>-1</sup>). The competition indices indicate that the bean cultivation in association favors the total relative yield without showing aggressive behavior between crops (A = 0); triticale and faba bean share their competitive capacity (CR>1) according to staggered plantings with and without biostimulant in a certain phenological state of triticale.</p>

Improving quantity and quality of sugar beet yield using agronomic methods in summer cultivation

The effect of agronomic factors on the amount of water consumption and its productivity in arid and semiarid regions is very important. This study was conducted to diagnose agronomical procedures for increasing the yield and water productivity of sugar beet in two years (2016 and 2017). The experimental factors were: sowing date (spring and summer), planting arrangement (25–50 cm and 40–50 cm, double rows with a distance of 25 cm or 40 cm and a distance between each double row of 50 cm), and plant density (90, 120 and 160 thousand plant/ha). In the second year, the harvesting date, which consisted of conventional (October) and delayed (November), was added to the experiment. High temperature during and immediately after planting decreased emergence on the summer sowing date. The uniformity of roots and irrigation water productivity (WPirrig) in spring crops was higher than those of summer crops; meanwhile, on the summer sowing date, water consumption declined by 27% (and the sugar yield decreased intensively by 44%). Furthermore, planting arrangements of 25–50 resulted in better plant establishment and eventually increased the number of final plants. Besides, increasing plant density improved the uniformity of plants root. Sowing in summer compared to spring reduced root and sugar yield on a conventional harvesting date by about 40%. After 25 days’ delay in harvesting time on both sowing dates (by mean), root yield, sugar yield, and WPirrig, increased by about 14, 28 and 22%, respectively. In general, at moderate densities (about 120 000), planting arrangement 40–50 and at low densities (less than 90 000, which usually occurs on the summer sowing date), planting arrangement 25–50 is recommended to increase yield and WPirrig.

The Unique Ability of Fine Roots to Reduce Vegetated Coastal Dune Erosion During Wave Collision

Vegetated coastal sand dunes can be vital components of flood risk reduction schemes due to their ability to act as an erosive buffer during storm surge and wave attack. However, the effects of plant morphotypes on the wave-induced erosion process are hard to quantify, in part due to the complexity of the coupled hydrodynamic, morphodynamic, and biological processes involved. In this study the effects of four vegetation types on the dune erosion process under wave action was investigated in a wave flume experiment. Sand dune profiles containing real plant arrangements at different growth stages were exposed to irregular waves at water levels producing a collision regime to simulate storm impact. Stepwise multivariate statistical analysis was carried out to determine the relationship of above- and below-ground plant variables to the physical response. Plant variables included, among others, fine root biomass, coarse root biomass, above-ground surface area, stem rotational stiffness, and mycorrhizal colonization. Morphologic variables, among others, included eroded sediment volume, cross-shore area centroid shift, and scarp retreat rate. Results showed that vegetation was able to reduce erosion during a collision regime by up to 37%. Although this reduction was found to be related to both above- and belowground plant structures and their effect on hydrodynamic processes, it was primarily accounted for by the presence of fine root biomass. Fine roots increased the shear strength of the sediment and thus lowered erosional volumes and scarp retreat rates. For each additional 100 mg/L of fine roots (dry) added to the sediment, the erosional volume was reduced by 6.6% and the scarp retreat rate was slowed by 4.6%. Coarse roots and plant-mediated mycorrhizal colonization did not significantly alter these outcomes, nor did the apparent enhancement of wave reflection caused by the fine roots. In summary, fine roots provided a unique ability to bind sediment leading to reduced dune erosion.

Pengaturan Populasi Tanaman untuk Meningkatkan Produktivitas Padi pada Lahan Rawa Pasang Surut

Increasing rice productivity on tidal swamp area need to meet available and affordable technologies. Plant population arrangement through planting method is the one of the cultivation technology which not widely adopted yet by farmers in tidal swamp ecosystem. Farmers generally used scattered plant arrangement called hambur. The research was conducted on tidal swamp type B at Karang Agung’s Experimental Field and farmer’s field in Sukaraja Village, Tungkal Ilir District, Banyuasin Regency, South Sumatera, 2018. The experiment was arranged by using split plot design with three replications. The main plot was rice variety (consisted of Inpara-2 and Inpara-8) and sub plot was plant population consisted of [1] Farmer’s practice (hambur/scattered), [2] Legowo 2:1 (213.333 population/ha), [3]Jarwo ganda 1 (376.470 population/ha), and [4] Jarwo ganda 2 (571.428 population/ha). Plant population arrangement in tidal swamp area was significantly effected by location and variety. Legowo 2:1, jarwo ganda 1 and jarwo ganda 2 had significantly higher yield than hambur. Hambur showed higher panicle number per m2 but lower grain filling ability and grain number per panicle. Through plant population arrangement, farmers could reached higher yield and saving seed consumption. Meanwhile, Inpara-2 tended to be more adaptive to population arrangement than Inpara-8. The jarwo ganda 1 with 376,470 plant/ha showed the highest yields for the Inpara-2 variety. Furthermore, we need to identify simple mechanization to help farmer for sowing by adopt plant population arrangement in tidal swamp land

Tuber Production, Gas Exchange, and PAR (Incident On Leaf Surface) of Potato Cultivars in Response to the Planting Patterns and Drip Irrigation System

The performance of potato cultivars was evaluated using four planting arrangements and drip irrigation on some photosynthetic traits and tuber production and weight in Ardabil region, Iran during 2017–2018. The results showed that planting arrangement significantly affected tuber weight traits per plant, photosynthetic carbon dioxide source of leaf surface (C ref), photosynthetic active radiation of leaf surface (Q Leaf), atmospheric pressure (P), decomposed carbon dioxide of leaf surface (C ' an), decomposed water of leaf area (e ' an), and total exchanged carbon dioxide (ΔC) at 1% probability level. The highest amounts of photosynthetic traits (C ref) and (Q Leaf) in the Milva cultivar with the planting arrangement of four rows with a width of 150 cm were found to be 434.90 mg kg-1 and 10.85 μmol m-2 s-1, respectively, which increased by 17 mg kg-1 and 2.53 μmol m-2 s-1, respectively, compared to the control (two rows with a spacing of 150 cm with surface irrigation and a planting density of 53,333 plants per hectare) (R1). The high C ref resulted from removing the vacant space and from maximum use of resources. The increased Q Leaf is due to the zigzag placement of plants, received radiation level, and photosynthetically active radiation on the leaf surface. Considering acceptable changes in the studied traits, cultivating the Milva cultivar with a planting arrangement of four rows is recommended in the Ardabil region.

Planting Arrangement and Effects of Planting Density on Tropical Fruit Crops—A Review

With the growing importance of fruits as valuable food resources, attention has been paid in recent years to enhance productivity and quality. Increasing productivity per unit area through agronomic management is one of the important strategies to increase the production of fruit crops. Keeping this view, this review was undertaken to improve understanding of the planting arrangement and the effect of planting density on productivity and quality of fruit crops. This review will thus provide updated and in-depth information about the influence of planting density on yield and fruit quality, which will also be useful for the growers, consumers, exporters, and processing industry. In fruit crops, the effect of plant density and planting arrangement is well documented. From the review, it is understood that yield per unit area is the product of fruit yield plant−1 and the number of plants per unit area. Fruit size increases with a decreasing planting density, while total yield increases with an increasing density at a certain level. However, fruit quality decreases with an increasing planting density.

Agroforestry and Household Food Security Status among Small-Scale Farmers in Kubo South and Samburu Wards of Kwale County, Kenya

This study investigated the contributions of agroforestry to household food security in Kwale County. The study objectives were to determine the status of agroforestry, the status of household food security, and the relationship between agroforestry and household food security. Descriptive cross-sectional survey research design was applied, with multistage sampling procedure, which comprised of purposive and random sampling for selection of the study sites and respondents from different villages in Kubo south and Samburu wards, Kwale County. The sample size for the study comprised of 270 smallholders and 10 key informants. The study used a combination of instruments, namely, structured questionnaires, focus group discussions, observation, and interview schedules. Descriptive statistics and regression analysis were used to test relationship between agroforestry and household food security. The study found that 14.1 % were food secure, 2.96 % households mildly food insecure, 54.81 % were moderately food insecure and 27.41 % were severely food insecure. Majority of farmers practice agrosilvopastoral system of agroforestry due to the multiplicity of social, economic, and environmental benefits they derive from it. The results further indicated that challenges facing agroforestry farmers include poor access to credit, inadequate extension services, wildlife destruction, pests and diseases, and inadequate markets for agroforestry products. The study concludes that there is high level of food insecurity among smallholder farmers and recommends concerted efforts by county and national governments to intensify the practice of agroforestry, improvement of access to inputs for agroforestry, allocate more land for agroforestry practice, proper tree species selection, adoption of best agroforestry practices based on research, and suitable tree planting arrangements for improved household food security.

Response of Maize, Cotton, and Soybean to Increased Crop Density in Heterogeneous Planting Arrangements

The reduction of row spacing and increase of crop population density are important tools for maximizing crop yield. For this strategy to be effective, the crop population should not create intraspecific crop competition that penalizes yield. Thus, planting arrangements that increase light interception throughout the canopy without increasing row spacing might be needed to maintain yield. In this study, heterogeneous planting arrangements on evenly spaced rows were analyzed for maize (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max (L.) Merr.). Each crop had four planting arrangements: (1) normal density in all rows, considered the control, (2) doubled density in all rows, (3) a sequential arrangement of normal and tripled densities (each in every other row; NTNT), and (4) normal-tripled-tripled-normal (NTTN). Maize and cotton did not exhibit changes in growth and architecture when comparing uniform and variable planting arrangements. Soybeans were more adaptable and increased biomass production by 44% to 45% in variable arrangements. None of the crops showed differences in yield due to planting arrangement, so the use of rows with different densities might not be needed when using high densities to maximize yield.

Techno-economic analysis and Monte Carlo simulation for green hydrogen production using offshore wind power plant

With the growth of marine energy such as offshore wind power, hydrogen is a promising solution for the intermittence of renewable energy sources and long-distance transmission. Some demonstration projects of offshore hydrogen production are underway using wind power. However, comparative studies on novel options such as individual hydrogen production and transport to land from each wind turbine, have not advanced beyond conceptual suggestion. In this study, to determine the most economical method of connecting offshore wind power plants and hydrogen production facilities, a techno-economic analysis of three offshore wind power plant arrangements is presented, including distributed hydrogen production, centralized hydrogen production, and onshore hydrogen production. As a method for feasibility comparison, net present value calculation, sensitivity analysis, and Monte Carlo simulation are suggested and analysis results for three arrangements are presented. In particular, the results of the proton exchange membrane electrolysis system model that is developed in the previous study are applied in order to determine the hydrogen production efficiency. Calculated hydrogen production cost was 13.81, 13.85, 14.58 $/kgH2 for distributed case, centralized case, and onshore hydrogen production case, respectively. The analysis results show that distributed case has the most competitive case due to the absence of expensive High Voltage Direct Current cable and offshore substation. Sensitivity analysis shows it is necessary to maintain capacity factor.

Artificial Neural Network-Based Planting Arrangement of Smart City in Green Ecological Environment

The traditional urban planting arrangement is largely limited by the designer’s idea and has a high repetition rate and a low reference reuse rate. Therefore, a scientific and reasonable planting arrangement of the urban environment is necessary. In this work, research on planting arrangements in a smart city is carried out under green ecology and environment. Firstly, the planting arrangement is analyzed based on the structure, characteristics, and basic principles of the artificial neural network (ANN) model. ANN is frequently applied in pattern recognition, signal processing, system identification, and optimization. In the field of control, neural networks are used to deal with the nonlinearity and uncertainty of the control system and to approximate the identification function of the system. Secondly, the output value of the planting arrangement in the smart city is calculated according to the error backpropagation algorithm. During this period, the weight is adjusted according to the Hebb criterion, and the relevant statistical model of planting arrangement in the smart city is analyzed by ANN. Finally, suggestions on planting arrangements are given. The research shows that steamed bun-shaped plants have the largest total number in smart cities, followed by spherical and bush-like plants. Planting arrangement for spherical and palm or coconut-form plants is more frequent while planting arrangements for wind-shaped plants have a lower frequency. In terms of the importance of the planting arrangement, these 18 types of plants are very important for the green ecological environment in the smart city. Finally, suggestions on planting arrangements are given according to the research.

Exploring the Integration Between Colour Theory and Biodiversity Values in the Design of Living Walls

Designing green infrastructure in cities requires vegetation that has multiple outcomes and functions, particularly using plants that have both attractive visual or aesthetic features and high biodiversity values. Plantings that have high visual appeal are more highly valued by people and increase their feeling of wellbeing. Increasing biodiversity in cities is one of the major challenges facing urban planning and design. However, balancing biodiversity and aesthetic outcomes in urban planting design is complex, and to date there are few methods that can be used to guide plant selection. To address this knowledge gap, we investigated the use of a colour theory framework for planting arrangements to see if we could design vegetation that is highly aesthetic and has high biodiversity. We did this by configuring planting combinations for living walls in Malmö, Sweden, using principles based on Johannes Itten’s colour theories. The plant combinations on each wall were graphically arranged using (1) colour analysis of each plant and (2) design of the plant species into two colour schemes: light-dark colour concept and a complementary colour concept. For each species used in the compositions we created a biodiversity classification, based on its pollination value, “nativeness” and conservation value as a cultivar; and a plant visual quality classification, based on the performance from living walls studies. The graphical colour composition and interlinked biodiversity value were then compared to designs created with randomly selected plant species. The results showed that it is possible to design a living wall based on colour theory without compromising with biodiversity outcomes, namely species richness, pollination and the nativeness of the species. The results also indicate the potential application of this design approach to deliver greater aesthetic appreciation and enjoyment from plantings. While more work is needed, this study has shown that a theoretical colour framework can be a useful tool in designing green infrastructure to improve delivery of both cultural and regulatory ecosystem services.

Genetic variability and effect of plant arrangement on corn

One of the factors of great influence on the agronomic performance of corn plants is their population arrangement. In this respect, the objective of this work was to evaluate the effect of plant arrangement and genetic divergence in different corn genotypes. The study was conducted in the county of Mineiros-GO, Brazil. The soil is Quartzarenic Neosol (Entisol). The experimental design used was in random blocks in factorial 8x2, totaling 16 treatments corresponding to 8 corn genotypes (A8740, A8088, DKB290, DKB390, DKB177, P30F35, P30S31 and P3707) and 2 spacing between lines (0.45 m and 0.90 m), 4 repetitions. The soil preparation was done in the no-tillage system. At the end of the experiment, biometric and productivity variables were measured and analyzed using Softwares R and Genes. The analysis of variance revealed significance in the simple and main effects. Genetic divergence and the effect of plant arrangement on corn genotypes were observed, where the variables plant height, stem diameter and the thousand grain mass were the main characteristics that influenced yield. Among the analyzed genotypes, the growing of genetic material DKB390 is recommended in rows spaced at 0.45 or 0.90 m, as it has plants with ears of greater number of grains, thousand grain mass and yield, demonstrating its plasticity in adaptation to the proposed systems.

Close‐spaced plant arrangement optimizes castor biomass and seed yields in tropical fall–winter conditions

AbstractThe high seed yield and optimum harvesting of short‐height castor (Ricinus communis L.) genotypes have enabled its large‐scale cultivation and introduction in the Brazilian cropping systems. Thus, studies to optimize plant density are essential to adequate plant population since this is the key management to influence castor biomass and seed production. This study aimed to evaluate the influence of plant density by altering plant arrangement (i.e., spacing between and within rows) on growth, biomass production and partitioning, and seed yield of a castor cultivar in fall–winter cropping season. Field experiments were conducted over two seasons in southeastern Brazil. Two close‐spaced (0.45 × 0.23 m and 0.45 × 0.44 m) and a traditional (0.90 × 0.44 m) plant arrangements were tested. Plant arrangements influenced plant growth, biomass production and partitioning, and seed yield. Compared to the traditional layout, close‐spaced plant arrangements resulted in thinner basal stems and lower leaf area per plant, but increased leaf area index. The plant arrangement with higher plant density increased per‐unit area production of stem plus leaf biomass (43–48%), which also resulted in increased (24%) seed yield, compared to traditional layout. Although a greater amount of biomass was partitioned to reproductive organs in close‐spaced plant arrangements, this allocation was not enough to influence the harvest index. Therefore, the adaptive performance of short‐height castor adjusting biomass partitioning to maximize stem plus leaf biomass production and seed yield at close‐spaced plant arrangement demonstrated this to be a suitable option to cultivate in the Brazilian fall–winter season.

Desempenho produtivo de soja em diferentes manejos de espaçamento e densidade de plantas

The spatial arrangements of soybean plants appear as important variables, as adjustments to the spacing between the lines, as well as plant densities, can result in significant productivity gains. The objective of this study was to evaluate the productive performance of soybean in different spacing arrangements. No significant statistical difference was observed for the productivity variable, however, the economic analysis showed productivity gains (4.51sacks/ha -1) a gain of 7.2% R$/ha -1. Although this value does not represent a statistically significant value, for the rural producer it means a considerable monetary result, since for large properties this value increases gradually.

Trinexapac-ethyl application time in the crop corn agronomic performance grown under different plant arrangements

Reduced row spacing promotes more uniform spatial distribution of plants in the field. However, the adoption of reduced row spacing only is possible with smaller plants, which may be obtained with the use of plant growth regulator. This study aimed to evaluate the agronomic performance of the first corn crop with Trinexapac-ethyl applied at the different plant development stages and grown under different row spacing, with the same plant population. The experiments were arranged in a split-plot randomized block design with four replications, with row spacing for the plots (0.45 and 0.90 m) and Trinexapac-ethyl (TE) application time to subplots (control without application, at the V3, V6, V9 and V12 phenological stages). The Trinexapacethyl application time interacted with row spacings changing the growth and yield performance of the corn crop. For 0.45 m spacing Trinexapac-ethyl application at V12 and for 0.90 m spacing application at V9 and V12 reduced plant height and ear height. Trinexapac-ethyl application at V9 for both row spacings changed the plant architecture without changing the ear length and grain yield.

Maize yield in response to alternating low- and high-density rows of diverse hybrids

Production of rainfed summer crops like maize (Zea mays L.) must adapt to a changing climate and retain high productivity. Using diverse hybrids in the same stand is a simple way to adapt to unpredictable stresses during the growing season. However, some hybrids are available at a price premium and therefore their use needs to be cleverly incorporated in the system to balance cost and economic return. In a two-year study in Pennsylvania, we evaluated maize yield and economic return in response to combinations of two planting densities (4.6 and 8.9 plants m-2), two planting arrangements (rows with the same density or alternating rows of low and high density with medium overall density), and two hybrids (drought tolerant Aquamax and a non-drought tolerant Seedway hybrids), including mixtures of both density and hybrid. Both experimental years received adequate rainfall for production. Regression showed that increasing plant density by 1 plant m-2 increased biomass and grain yield by 2% in the density range tested. Using the Aquamax hybrid increased grain yield by 6% compared with Seedway in one of two years. However, economic analysis indicated lower returns when using the higher planting density. Using low density, or a medium density by alternating low and high-density rows, optimized economic output and yield. In 2019, mixing hybrids suppressed yield by reducing the number kernels per ear by 9% compared to pure hybrid stands, mostly for the Aquamax hybrid, which suggests that combining compatible hybrids is of primary importance in mixtures. In rotations highly dependent on maize yield, a combination of defensive agronomic tactics that keeps costs low and yield slightly below the attainable yield as proposed here may result in a resilient and profitable agricultural system adapted to a variable climate.

Yields of Promising Sugarcane Clones under Three Different Planting Arrangements

A field experiment was conducted at Kediri, East Java, to examine the influence of row spacing on the yield of five promising clones from August 2018-June 2020. The investigation was of a Split-Plot design with three replications. The main plot consisted of three planting arrangements: SR, single row spacing at 110 cm, DR1, double rows spacing 50+135 cm, and DR2, double rows spacing 50+170 cm. Sub-plots consisted of five promising clones and one check variety: MLG 5, MLG 9, MLG 14, MLG 52, MLG 55, and PS 881. The results suggest no overall significant effect of planting arrangement on sugar yield, though clones may vary. There are significant differences in yield between some clones. Wider rows, DR2, show the highest yield in tonnes of cane per hectare (TCH) in PC (153.94 t/ha) with a slight decrease (14%) in RC-1 due to reduced plant population. Sugar yield in tonnes of sugar per hectare (TSH) in various planting arrangements ranges from 12.26-13.99 t/ha in PC and 10.68-11.93 t/ha in RC-1. MLG 9 can be released as a new variety with high cane and sugar yields.

The contribution of plant spatial arrangement to bumble bee flower constancy.

Floral constancy of foraging bees influences plant reproduction. Constancy as observed in nature arises from at least four distinct mechanisms frequently confounded in the literature: context-independent preferences for particular plant species, preferential visitation to the same species as the previous plant visited (simple constancy), the spatial arrangement of plants, and the relative abundances of co-flowering species. To disentangle these mechanisms, we followed individual bee flight paths within patches where all flowering plants were mapped, and we used step selection models to estimate how each mechanism influences the probability of selecting any particular plant given the available plants in a multi-species community. We found that simple constancy was positive: bees preferred to visit the same species sequentially. In addition, bees preferred to travel short distances and maintain their direction of travel between plants. After accounting for distance, we found no significant effect of site-level plant relative abundances on bee foraging choices. To explore the importance of the spatial arrangement of plants for bee foraging choices, we compared our full model containing all parameters to one with spatial arrangement removed. Due to bees' tendency to select nearby plants, combined with strong intraspecific plant clumping, spatial arrangement was responsible for about 50% of the total observed constancy. Our results suggest that floral constancy may be overestimated in studies that do not account for the spatial arrangement of plants, especially in systems with intraspecific plant clumping. Plant spatial patterns at within-site scales are important for pollinator foraging behavior and pollination success.