Interplant Spacing Research Articles

Plant Identification in Mosaicked Crop Row Images for Automatic Emerged Corn Plant Spacing Measurement

Image processing algorithms for individual corn plant and plant stem center identification were developed. These algorithms were applied to mosaicked crop row image for automatically measuring corn plant spacing at early growth stages. These algorithms utilized multiple sources of information for corn plant detection and plant center location estimation including plant color, plant morphological features, and the crop row centerline. The algorithm was tested over two 41 m (134.5 ft) long corn rows using video acquired two times in both directions. The system had a mean plant misidentification ratio of 3.7%. When compared with manual plant spacing measurements, the system achieved an overall spacing error (RMSE) of 1.7 cm and an overall R2 of 0.96 between manual plant spacing measurement and the system estimates. The developed image processing algorithms were effective in automated corn plant spacing measurement at early growth stages. Interplant spacing errors were mainly due to crop damage and sampling platform vibration that caused mosaicking errors.

Optimal spacing for double-skin roofs

Double-skin design is known as an effective way to reduce the building's solar heat gain. In this study, inclined parallel plates with upper plate heated by a lighting system are used to simulate double-skin roofs exposed to solar irradiation. Heat transfer experiments were carried out for different inter-plate spacing and different inclined angles. In some of our test runs, a radiant barrier is also installed on top of bottom plate to further cut down the building's heat gain. The Nusselt numbers reduced from our test data are consistently matched with Azevedo and Sparrow's correlation. The optimal inter-plate spacing, when the most heat gain is blocked out, can be directly obtained from our test data which is very close to the sum of both plate's thermal boundary layer thicknesses.

Precipitation pulses and soil CO2 flux in a Sonoran Desert ecosystem

AbstractPrecipitation is a major driver of biological processes in arid and semiarid ecosystems. Soil biogeochemical processes in these water‐limited systems are closely linked to episodic rainfall events, and the relationship between microbial activity and the amount and timing of rainfall has implications for the whole‐system carbon (C) balance. Here, the influences of storm size and time between events on pulses of soil respiration were explored in an upper Sonoran Desert ecosystem. Immediately following experimental rewetting in the field, CO2 efflux increased up to 30‐fold, but generally returned to background levels within 48 h. CO2 production integrated over 48 h ranged from 2.5 to 19.3 g C m−2 and was greater beneath shrubs than in interplant spaces. When water was applied on sequential days, postwetting losses of CO2 were only half a large as initial fluxes, and the size of the second pulse increased with time between consecutive events. Soil respiration was more closely linked to the organic matter content of surface soils than to rainfall amount. Beneath shrubs, rates increased nonlinearly with storm size, reaching an asymptote at approximately 0.5 cm simulated storms. This nonlinear relationship stems from (1) resource limitation of microbial activity that is manifest at small time scales, and (2) greatly reduced process rates in deeper soil strata. Thus, beyond some threshold in storm size, increasing the duration or depth of soil moisture has little consequence for short‐term losses of CO2. In addition, laboratory rewetting across a broad range in soil water content suggest that microbial activity and CO2 efflux following rainfall may be further modified by the routing and redistribution of water along hillslopes. Finally, analysis of long‐term precipitation data suggests that half the monsoon storms in this system are sufficient to induce soil heterotrophic activity and C losses, but are not large enough to elicit autotrophic activity and C accrual by desert shrubs.

Flash Furnace Off-Gas Cooling in a Plate Column: Reduction of Pressure Drop by Column Design Modification

In the early 1990s, the Inco SO2 abatement project which aimed at a 60% reduction in SO2 emissions from the Copper Cliff Smelter included the installation of two new flash furnaces (the first in 1991 and the second in 1993). The flash furnace off-gas is cooled and cleaned through two new Monsanto Dynawave gas cleaning systems that replaced the traditional venturi scrubbing system. It was discovered that the flash furnace production capacity is often limited by the capacity of the gas cleaning system. The key task is to reduce the pressure drop in the system. The froth column which cools the gas from about 85 to 25 °C is responsible for the largest pressure drop in the gas cleaning system. Initially, the column was fitted with 22 plates, but in 1994, both #1 and #2 froth columns were modified by reducing the number of plates in each column from 22 to 18 and increasing the interplate spacing on the lower plates. With recent increasing demand for more throughput in the flash furnaces, excessive pressure drops have again become a limiting factor. In 2005, further modifications of the froth columns were made on the basis of recent data and estimates of the actual volume flows of gas within the column. The bottom plate (#18) of each column was removed and two small deflector baffles were added to reduce liquor entrainment at the bottom of the column. These modifications have reduced the overall gas pressure drops by just under 20% leading to a much improved operation of the gas cleaning system.

The gas holdup in a multiphase reciprocating plate column filled with carboxymethylcellulose solutions

Gas holdup was investigated in a gas-liquid and gas-liquid-solid reciprocating plate column (RPC) under various operation conditions. Aqueous carboxymethyl cellulose (sodium salt, CMC) solutions were used as the liquid phase, the solid phase was spheres placed into interplate spaces, and the gas phase was air. The gas holdup in the RPC was influenced by: the vibration intensity, i.e., the power consumption, the superficial gas velocity, the solids content and the rheological properties of the liquid phase. The gas holdup increased with increasing vibration intensity and superficial gas velocity in both the two- and three-phase system. With increasing concentration of the CMC PP 50 solution (Newtonian fluid), the gas holdup decreased, because the coalescence of the bubbles was favored by the higher liquid viscosity. In the case of the CMC PP 200 solutions (non-Newtonian liquids), the gas holdup depends on the combined influence of the rheological properties of the liquid phase, the vibration intensity and the superficial gas velocity. The gas holdup in the three-phase systems was greater than that in the two-phase ones under the same operating conditions. Increasing the solids content has little influence on the gas holdup. The gas holdup was correlated with the power consumption (either the time-averaged or total power consumption) and the superficial gas velocity.

REDUCTION OF SCOUR AROUND A BRIDGE PIER BY MULTIPLE COLLAR PLATES

ABSTRACT Scour around a bridge pier is one of the major possible causes of the hydraulic failures of a bridge. A typical sediment-water-structure interaction at the upstream junction of the bridge pier initiates a vortex system, the primary vortex of which is responsible for local scour around the pier. The growth of the primary vortex can be arrested by retaining it on a rigid surface as on a collar plate. A number of experiments covering various sizes of collar plates were carried out in an effort to minimize scour around a bridge pier. A collar plate of size three times the diameter of the circular pier, D or larger when placed at the average bed level assures 100% scour reduction while a collar plate of size 2D placed 0.1D below the bed does not allow scour depth to go beyond it. Anticipating degradation of general bed level, a group of multiple collar plates of smaller size were employed at the laboratory scale to reduce the scour considerably. A group of three collar plates of size 1,5D having an inter-plate spacing Cs of D/6 with the middle plate placed at the average bed level reduces scour by 83% in comparison to the scour depth of an unprotected pier. The composite device, apart from being axis symmetric, is highly suited to degrading river beds.

Rendimento e qualidade de cultivares de pepino para processamento em função do espaçamento de plantio

Avaliou-se o rendimento e a qualidade de cultivares de pepino para processamento em diferentes espaçamentos de plantio, em experimento em Petrolina (PE), de abril a julho/99. O delineamento experimental utilizado foi de blocos casualizados sendo os tratamentos dispostos no esquema fatorial 5 x 3, compreendendo cinco cultivares (Calypso, Eureka, Supremo, Vlaspik e Vlasset) e três espaçamentos entre plantas (0,20; 0,30 e 0,50 m) com três repetições. A parcela experimental foi composta de quatro linhas de 3,0 m espaçadas de 1,00 m, com duas plantas por cova, sendo as duas linhas centrais consideradas como área útil. Verificou-se efeitos lineares negativos na produtividade com o incremento do espaçamento entre plantas para as cultivares Vlaspik, Vlasset e Eureka, e efeitos quadráticos com pontos de mínima e máxima produtividade para as cultivares Calypso e Supremo. As maiores massas frescas de frutos foram observadas nas cultivares Vlaspik (35,44 g/fruto) e Vlasset (35,07 g/fruto) que não apresentaram diferenças entre si. Observou-se efeito linear positivo com o aumento do espaçamento entre plantas no número de frutos por planta para as cultivares Vlaspik, Vlasset e Supremo. Para as cultivares Calypso e Eureka constataram-se efeitos quadráticos com pontos de máximo número de frutos por planta. Na classificação de frutos comerciais não verificou-se efeitos significativos dos tratamentos.

Efeito de densidade de plantas na produtividade de cultivares de pepino para processamento tipo "cornichon"

O objetivo deste trabalho foi avaliar a produtividade de cultivares de pepino para processamento, tipo "cornichon", semeadas em diferentes espaçamentos. O experimento foi desenvolvido em Petrolina, PE, no período de abril a julho de 1999. Foram estudadas as cultivares para processamento Calypso, Eureka, Prêmio, Vlaspik e Vlasset e os espaçamentos entre plantas de 0,20, 0,30 e 0,50 m, em sistema rasteiro. Os tratamentos foram arranjados no esquema fatorial 5x3, em delineamento de blocos ao acaso, com três repetições. A parcela experimental foi composta de quatro linhas de 3,0 m, com espaços entre elas de 1,0 m, duas plantas por cova, e área útil constituída pelas linhas centrais. O incremento do espaçamento entre plantas teve efeitos lineares negativos na produtividade das cultivares Vlaspik, Vlasset e Prêmio. As menores produtividades das cultivares Calypso e Eureka ocorreram sob espaçamento, respectivamente, de 0,50 e 0,46 m. Os maiores valores de massa de matéria fresca dos frutos foram observados nas cultivares Vlasset (6,94 g/fruto) e Eureka (6,82 g/fruto) que não apresentaram diferenças entre si. Observaram-se efeitos lineares positivos do aumento do espaçamento entre plantas no número de frutos por planta em todas as cultivares. As cultivares apresentaram uma variação de 12,18 a 15,10% de frutos tipo 3 (5,0 a 5,5 cm de comprimento), tendo as cultivares Vlaspik (15,10%), Eureka (14,50%) e Calypso (13,60%) apresentado as maiores proporções, sem diferirem entre si.

Effects of Rashig rings placed in interplate spaces and the rheological properties of the liquid phase on power consumption in a gassed reciprocating plate column

The power consumption in a gassed reciprocating plate column with Rashig rings placed in interplate spaces increases with both increasing vibration intensity and content of solid particles but decreases with increasing the superficial gas velocity, regardless of the rheological properties of the liquid phase. Under the same operating conditions, the power consumption is higher when the column is filled with a non-newtonian liquid than with distilled water.

Commonness and Long‐Term Survival in Fragmented Habitats:Primula elatioras a Study Case

Abstract:In Flanders (northern Belgium), populations ofPrimula elatior( Primulaceae), an obligately outcrossing long‐lived perennial herb, are widely distributed in fragmented ancient deciduous forests. We used 15 allozyme loci to investigate population genetic variation and structure ofP. elatiorand quantified reproductive success in the form of fruit and seed production. Based on a sample of nine populations from Flemish forests, we related these variables to population size, density (interplant spacing within populations), and isolation. With only four polymorphic loci, the levels of genetic variation within populations were low compared with those of other species with similar life‐history traits. Small populations had significantly fewer alleles per locus than large populations but maintained high levels of heterozygosity. No effect of plant density was found on genetic variation within populations. Genetic differentiation among populations was low, indicating moderate levels of gene flow. Isolation by distance was observed, however, and small populations appeared to be more differentiated than large populations. These findings suggest genetic drift as a cause of loss of variation and divergence. Population size and plant density were correlated but affected fruit and seed production differently. A reduced seed production was found in small populations. Fruit abortion increased at high plant densities as a result of biparental inbreeding and neighborhood genetic structure. Our results indicate that being common is not a guarantee of long‐term survival in fragmented habitats. Conservation efforts must include widely distributed species so as to prevent population collapses and consequent species decline. Forest management has to take into consideration the preservation of the herbaceous layer and avoid logging practices that damage populations of forest herbs.

Gas holdup in a gassed reciprocating plate column with rashig rings placed in interplate spaces

AbstractThe gas holdup is studies in a gassed reciprocating plate column with the addition of the Rashig rings placed in each interplate space. The gas holdup generally increases with increasing the vibration speed, the superficial gas velocity, and the solids concentration in the range of operating conditions applied. Independently of the solids concentration, the gas holdup is correlated with the power consumption and the superficial gas velocity. The Rashig rings are shown to have more effective dispersion action than the polypropylene spheres under the same other operating conditions.

The influence of Rashig rings and the rheological properties of the liquid phase on the pressure drop at the bottom of a reciprocating plate column

The pressure drop at the column bottom, filled with a Newtonian (distilled water) or non-Newtonian (aqueous solution of carboxymethylcellulose, sodium salt, CMC, 1 %) liquid, in the presence of Rashig rings, made of aluminum (0.8 cm in diameter), regularly distributed in the interplate spaces (volume content of the solid phase: up to 3.2 %) was studied. The average and total pressure drop at the column bottom increased with increasing vibration speed and content of the solid particles, but decreased with increasing superficial gas velocity, indepentently of the rheological properties of the liquid phase. The pressure drop at the column bottom filled with the non-Newtonian liquid was found to be higher than that in the case of distilled water.

Productivity, economics and nitrogen-use efficiency of sweet corn (Zea mays saccharata) as influenced by planting geometry and nitrogen fertilization

A field experiment was conducted during rainy season of 2007 and 2008 at Wadura, Sopore, to study the effect of crop geometry (60 cm 15 cm, 60 cm 20 cm, 60 cm 25 cm, 60 cm 30 cm) and nitrogen levels (0, 30, 60, 90, 120 and 150 kg N/ha) on yield, yield attributes, nitrogen use efficiency, crop productivity, economics and nitro- gen balance of sweet corn ( Zea mays saccharata Sturt). Plant height, weight of green cobs, number of kernel/cob, 1,000-kernel weight and kernel recovery increased as the inter-plant spacing was increased from 15 to 30 cm, while the number of cobs/ha, plant dry weight and bareness increased with a decrease inter-plant spacing from 30 cm to 15 cm. The maximum cob yield was recorded at 60 cm 20 cm spacing which was higher than 60 cm 25 cm planting geometry. A decrease in planting spacing from 60 cm 20 cm to 60 cm 15 cm caused 33.2% reduc- tion in cob yield. The kernel yield and crop productivity, crop profitability, net returns, nitrogen uptake and nitrogen use efficiency were also higher at 60 cm 20 cm planting spacing. Increasing nitrogen levels upto 120 kg/ha showed marked improvement in plant height, plant dry weight, number of cobs/ha, number of kernels/cob, 1000- kernel weight, green cob weight and kernel recovery, which consequently improved the yield and return. While Barrenness in cobs also declined with increasing nitrogen levels. Highest nitrogen uptake, total availability and ac- tual residual soil nitrogen contents were observed at 150 kg N/ha. Increasing nitrogen levels progressively re- duced agronomic and physiological nitrogen use efficiency. A level of 125.7 kg N/ha was found to be economic optimum with green cob yield of 14.21 t/ha and a response of 7.55 t/ha. The response to optimum level of N was found to be 60.09 kg green cob/kg N applied. Hence, crop geometry of 60 cm 20 cm with nitrogen level of 120 kg/ha should be adopted to obtain the maximum green cob yield and net profit from sweet corn in Kashmir valley.

Two-dimensional instability study of a thermoacoustic prime-mover

A numerical model aimed at investigating the development of instability in a thermoacoustic prime-mover is presented. It is based on a discretization of the two-dimensional compressible Navier–Stokes equations, and does not rest on the plane pressure wave assumption. The computational domain is made of a single stack interplate space extended up to both resonator ends. The working gas is assumed to be initially at rest, and a longitudinal temperature gradient is enforced. The linear instability properties of the system are then given by the eigenmodes of the discretized evolution operator linearized in the vicinity of the above basic state. Temporal growth rate and oscillation frequency are thus obtained for all thermoacoustic modes, and the prime-mover instability onset is determined as a function of the various parameters (mainly temperature gradient magnitude and mean pressure). As far as linear instability is concerned, this formulation is attractive, since it avoids any direct numerical simulation and any problem involved by the presence of two very different time scales.

Instability in a thermoacoustic prime-mover: A numerical approach

A numerical model aimed at investigating the development of instability in a thermoacoustic prime-mover is presented. It is based on a discretization of the two-dimensional compressible Navier–Stokes equations, and does not rest on the plane pressure wave assumption. The computational domain is made of a single stack interplate space extended up to both resonator ends. The working gas is assumed to be initially at rest, and a longitudinal temperature gradient is enforced. The linear instability properties of the system are then given by the eigenmodes of the discretized evolution operator linearized in the vicinity of the above basic state. Temporal growth-rate and oscillation frequency are thus obtained for all thermoacoustic modes, and the prime-mover instability onset is determined as a function of the various parameters (mainly temperature gradient magnitude and mean pressure). As far as linear instability is concerned, this formulation is attractive, since it avoids any direct numerical simulation and any problem involved by the presence of two very different time scales.

A comparison of bumblebees’ movements in uniform and aggregated distributions of their forage plant

Summary1. Movements by bumblebees Bombus lapidarius were studied in arrays of plants of oil‐seed rape Brassica napus cv Westar. In the arrays, plants were arranged into either a uniformly dispersed configuration or a patchily dispersed configuration.2. Progress across an array was measured as the distance bumblebees had moved away from an original plant location after eight subsequent, successive plant visits. Movements were analysed in units of both metres and inter‐plant spaces. In both units, bumblebees progressed more slowly across patchily dispersed arrays.3. Plant dispersion had a detectable effect on certain components of bees’ individual inter‐plant moves (e.g. move length in metres) but not on others (e.g. mean turning angle). In some cases, the effects of aggregation on the components of individual moves were probably too small to detect statistically and only emerged in their cumulative effect on bees’ progress.4. Over short sequences of plant visits, bumblebees revisited plants rarely, but the frequency of revisits was almost twice as high in patchy arrays as in uniform arrays, and economic penalties may result from foraging among highly aggregated plants.5. The effects of plant dispersion on pollinator movements detected in this study are unlikely to have a major impact on pollen transfer in B. napus because differences in pollinator progress only emerged after several successive inter‐plant flights away from a potential pollen source, by which time the limited extent of pollen carryover in this species means that fertilisations from the source plant would be very rare.

The influence of plant spacing on density-dependent versus frequency-dependent spore transmission of the anther smut Microbotryum violaceum.

The anther smut fungus Microbotryum violaceum is a pollinator-transmitted plant disease. As for other vector-borne diseases, frequency-dependent transmission patterns are predicted, in contrast to the density-dependent transmission of passively spread diseases. Frequency dependence will, however, only arise if vectors compensate for varying plant spacings. To test this assumption, we set up experimental populations of the host plant, Silene latifolia, with varying disease density (number of diseased plants per plot) and frequency (proportion of plants diseased), and three different plant spacings. We measured spore deposition on healthy flowers in these plots on two dates. Spore deposition decreased considerably from the first to the second census, perhaps related to the concomitant decrease in inflorescence sizes of diseased plants. At our first census, spore deposition rates varied with disease frequency, and the effect of frequency depended on plant spacing. While spore deposition was positively frequency dependent at the 1.5-m inter-plant spacing, no effect of disease frequency was found at a spacings of 0.5 m or 3 m. Nor was there an effect of disease density on spore deposition at the first census. At the later census, on the other hand, spore deposition increased almost significantly with increasing disease density (P = 0.08). This difference in deposition pattern together with a significant decrease in spore receipt indicates changes in pollinator spectrum and/or activity. The correlation of spore numbers among flowers within plants, an indication for intra-plant moves by vectors, was significant at 0.5 m and 1.5 m but not at 3 m. Floral traits and sex of individual plants influenced the number of spores they received. On the first census date, spore deposition increased with increasing inflorescence size in female but not in male plants. On the second census date, neither sex nor number of open flowers had an effect on spore receipt. None of the experimental plants became infected, however, probably because of the unusually hot and dry weather.

The Effect of Nutrients and Spacing on Neighbor Relations in Cardamine pensylvanica

I used a one-dimensional hierarchical design to determine the effect of local versus long-distance neighbors on the growth and reproduction of the annual weed, Cardamine pensylvanica. I measured the response of target plants to the presence or absence of neighbors at the first- and second-nearest neighbor positions and to the overall spatial pattern (clumped, even, or random) of neighbors. In addition, I investigated how variation in interplant spacing and nutrient levels combined with neighbor effects to influence the growth and reproduction of C. pensylvanica. How plants were affected by their neighbors depended upon nutrient levels, plant spacing, and the number of first- and second-position neighbors. Under low nutrient conditions and the closest spacing (0.5 cm), plant growth was so restricted that individual neighbor effects were overshadowed by the overall density effect. At the intermediate spacing (1.0 cm), both the first and the second neighbors influenced fruit number, but at the farthest spacing (1.5 cm) only the first neighbor was significant. Under high nutrient conditions, at all three spacings, first neighbors significantly affected biomass and fruit number, but there were differences among the spacing treatments in how target plants were affected by neighbors. Furthermore, under high nutrients there was a significant global pattern x first neighbor interaction. C. pensylvanica grown in the clumped global pattern with no neighbors at the first position produced significantly more fruit than did plants under any of the other global x neighbor combinations. Although long-distance interactions were only important under special circumstances, their effect was dramatic (an almost two-fold increase in fruit production). This study represents the first experimental test of the assumptions underlying the use of cellular automata models to model plant population dynamics. The results support the basic assumption of cellular automata models, i.e., that nearest neighbor interactions explain most of the variation in growth of plants. However, they also show that under certain conditions long-distance interactions also can have a great influence on the local neighbor effects. Before cellular automata models are extensively applied to model plant populations, further empirical work is needed to determine how competitive relationships among plants change with environmental conditions.

Response of the soil nematode community in a shortgrass steppe to long-term and short-term grazing

Nematode abundance and community structure were used to determine if grazing by cattle was a disturbance to soil. Soil samples were collected in bare ground, interplant spaces and under Bouteloua gracilis (H.B.K.) Lag. ex Griffiths (blue grama) in the arid shortgrass steppe of Colorado. Grazing treatments were long-term grazed (GG), long-term ungrazed (UU), short-term grazed (UG) and short-term ungrazed (GU). Long-term treatments were fifty-five years old. The short-term treatments were either grazed (GU) or ungrazed (UG) from 1939–1991, and then ungrazed or grazed for 2 years, from 1992–1994. Bacterial feeding nematodes and plant parasitic nematodes were the dominant nematode trophic groups. Grazing treatments had no effect on nematode absolute abundances, but did influence the percent contribution of fungal feeding nematodes. Total nematodes were higher in the under-plant locations, as were all trophic groups except omnivores and predators which had similiar densities in both locations. However, on a percentage basis, community composition was similar except for omnivores which were higher in the interplant location. These results suggest that grazing has no effect on belowground biota in the shortgrass steppe, with the exception of fungal feeding nematodes.

Effect of Sowing Spacing on Vegetative Growth, Dry Matter Production, and Peanut Pod Yield

Abstract Peanut growth and pod yield are influenced by sowing spacing and plant density. Production and distribution of dry matter on peanut cultivars sown in different spacings and densities and their relationships with pod and kernel yields were assessed. The factors evaluated were two cultivars (Florman INTA, virginia-type “runner” and Colorado Irradiado, valencia-type erect), three interrow spacings (IRS) (0.70, 0.50, and 0.30 m) and two interplant spacings (IS) (0.06 and 0.12 m). The 12 treatments were disposed in a factorial arrangement of 2×3×2 and a randomized block design with three replications. Weeds were controlled with Imazetapir (100 g ai/ha) and also hand weeded while leaf spot control was done with Fluzilasole (60 g ai/ha). Sowing spacings did not affect phenologic stage duration, but the differences observed were due to the cultivar. Vegetative growth was sensitive to spacings effect. At an individual plant level, dry matter and leaf area decreased significantly because of the greater intraspecific competition produced by the shortening of distances between rows (from 0.70 to 0.30 m) and between plants (from 0.12 to 0.06 m) and the corresponding density increase from 12 to 56 plants/m2. However, at a population level, most compact spacings produced more dry matter per surface and leaf area index. This also is related to the lesser time required for plants at these spacings to achieve a radiation interception higher than 90%. Dry matter distribution did not vary with sowing spacings. The number of branches per plant was reduced with the increase of density. The effect was greater in the late maturing cultivar. The most compact sowing spacings (0.30×0.06, 0.50×0.06 and 0.30×0.12 m) produced higher pod and kernel yield/ha than those less dense. This response is based upon the significant correlations between the dry matter and number of branches per surface area, and leaf area index and pod yield.