scholarly journals Differential Effect of Population Density on Shape and Size of Cylindrical Red Beet Genotypes

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 804A-804
Author(s):  
I.L. Goldman
Keyword(s):  
Population Density ◽  
Differential Effect ◽  
Row Spacing ◽  
Low Density ◽  
Population Densities ◽  
Lower Yield ◽  
Red Beet ◽  
Length Width ◽  
Shape And Size

The use of cylindrically shaped red beet cultivars for production of processing beets has increased in recent years. Yield and shape of globe-shaped red beet cultivars are determined in part by population density and within-row spacing; thus, it is thought cylindrical cultivars are similarly affected by these factors. The objective of this investigation was to evaluate the effects of population density on shape and size of cylindrical red beet cultivars. Two F1 hybrids and two open-pollinated cultivars were planted in replicated trials consisting of three population densities during 1993 and 1994. Ten traits were measured on a randomly selected sample of beets from each plot. Averaged over genotypes, significant differences among densities were found for percent harvestable beets per plot, length × width, harvest weight, length, and mid-width. Average over genotypes, greater harvest weight, higher percentage of harvestable beets, and greater length, mid-width, and length × width values were found at low density. Average over densities, open-pollinated cultivars exhibited a greater degree of straightness along with lower yield, harvest weight, and percent harvestable beets than their hybrid counterparts. These data demonstrate population density has a differential effect on shape and size of cylindrical beet genotypes.

scholarly journals Differential Effect of Population Density on Shape and Size of Cylindrical Red Beet (Beta vulgaris L.) Genotypes

1995 ◽  
Vol 120 (6) ◽  
pp. 906-908 ◽  
Author(s):  
I.L. Goldman
Keyword(s):  
Population Density ◽  
Shape Index ◽  
Weight Percent ◽  
Width Ratio ◽  
Lower Yield ◽  
Red Beet ◽  
Length Width ◽  
Genotype Interaction ◽  
Bottom Width ◽  
Shape And Size

The effects of population density on shape and size of cylindrical red beet genotypes were evaluated in a field experiment during 1994 and 1995. Two F1 hybrids and two open-pollinated genotypes were planted in replicated trials consisting of three population densities. Yield, harvest weight, percent harvestable beets per plot, length, middle width, top width, bottom width, length × width, length to width ratio, and a shape index (SI) were measured on a sample of beet plants from each plot. The density × genotype interaction was nonsignificant for all 10 traits. Averaged over genotypes, significant differences among densities were found for harvest weight, percent harvestable beets per plot, length, middle width, and length × width. In general, greater harvest weights, a higher percentage of harvestable beets, and greater length, middle width, and length × width values were found at low density. Averaged over densities, significant differences among genotypes were measured for all 10 traits. The open-pollinated genotypes Cyndor and Cylindra exhibited lower yield, lower harvest weight, greater SI, and a higher percentage of harvestable beets than their hybrid counterparts. These data demonstrate that population density has a differential and significant effect on the shape and size of cylindrical beet genotypes.

Evaluation of row spacing and population density effects on grain sorghum over a range of northern Australian environments

1981 ◽  
Vol 21 (109) ◽  
pp. 210 ◽  
Author(s):  
GA Thomas ◽  
RJK Myers ◽  
MA Foale ◽  
AV French ◽  
B Hall ◽  
...  
Keyword(s):  
Population Density ◽  
Full Range ◽  
Moisture Stress ◽  
Grain Sorghum ◽  
Row Spacing ◽  
Root Pruning ◽  
Population Densities ◽  
Planting Dates ◽  
Wide Range ◽  
Growing Conditions

Fifteen experiments were conducted between 1976 and 1978 to determine the response of grain sorghum to row spacing and population density over a range of soil types, planting dates and seasonal conditions. One experiment was at Kununurra, Western Australia, and the rest were in southern and central Queensland. The trials virtually covered the full range of growing conditions likely to be experienced in the sorghum growing area. Narrow and standard single rows (0.33 m to 1.07 m spacings) yielded as well as or better than more widely spaced (1.50 to 4.27 m) single or twin rows (0.33 or 0.36 m apart) at equivalent population densities over a wide range of yield levels. Only at yield levels below 900 kg ha-l was there a trend for 2.00 or 2.13 m twin rows to outyield the 0.33 or 0.36 m single row spacing. Significant yield reductions resulted in a number of trials, at yield levels above 1600 kg ha-l, from the use of wide row spacings. Where there was severe water stress, grain yields were also reduced by high population densities (>150,000 plants ha-l), particularly at the 0.33 or 0.36 m row spacing. There was no evidence that response to row spacing differed between cultivars. In the one experiment where it was studied, root pruning had no effect on grain yield under conditions of ample moisture supply, but yield was reduced by root pruning of wide row sorghum (1.8 m spacing) under conditions of moisture stress.

EFFECTS OF ROW SPACING AND POPULATION DENSITY ON GRAIN SORGHUM PRODUCTION IN SOUTHERN ALBERTA

1976 ◽  
Vol 56 (1) ◽  
pp. 31-37 ◽  
Author(s):  
B. R. HEGDE ◽  
D. J. MAJOR ◽  
D. B. WILSON ◽  
K. K. KROGMAN
Keyword(s):  
Population Density ◽  
Grain Yield ◽  
Yield Components ◽  
Growing Season ◽  
Grain Sorghum ◽  
Row Spacing ◽  
Population Densities ◽  
Southern Alberta ◽  
Sorghum Production ◽  
Narrow Row

Row spacings of 18–72 cm and population densities of 75,000 to 346,000 plants/ha had no consistent effect on grain yield of two sorghum hybrids (Pride X4004 and Pride X4053) because of compensating variations within yield components. Grain yield per panicle increased as row spacing increased but this was offset by a decrease in panicles per plant and panicles per square meter. Grain yield per panicle, panicles per plant, and panicles per square meter decreased as population density increased. The choice of row spacing and population density in field production will, therefore, depend on convenience factors related to crop management. Evapotranspiration for the growing season was 179 mm in 1973 and 204 mm in 1974. Highest water use efficiencies occurred at the low population densities and narrow row spacings. There were differences between the two hybrids. Grain yield of Pride X4004 was greater than that of Pride X4053 because the former produced a greater number of seed-bearing tillers. Grain yield differences in Pride X4004 among the three experiments were due to differences in grain yield per panicle.

Experiments on Substrate Selection by Corophium Volutator (Pallas): Depth Selection and Population Density

1964 ◽  
Vol 41 (4) ◽  
pp. 677-687 ◽  
Author(s):  
P. S. MEADOWS
Keyword(s):  
Population Density ◽  
Substrate Selection ◽  
Corophium Volutator ◽  
Population Densities ◽  
Surface Population ◽  
Different Depths ◽  
High Level ◽  
Animal Size ◽  
Substrate Depth ◽  
Shape And Size

1. An apparatus is described for testing substrate-depth preferences of Corophium volutator (Pallas). 2. Corophium burrow in mud whatever its depth, if only one depth of mud is available. 3. If presented with muds of different depths, more animals burrow in the deeper muds. Very shallow muds, of 0.5 cm. depth, are particularly avoided. 4. Although preferring deeper muds, animals are persuaded to burrow in shallow muds when the surface population density in the deeper muds is at a high level (> 0.1 animals/cm.2). This would be explained by a pattern of territorial behaviour which shows itself only at relatively high population densities. 5. Analysis of the distribution of animals at low densities indicates some tendency towards gregariousness. 6. Because of the periodic tendency for animals to vacate their burrows and burrow elsewhere, more than 50% of burrows at very low surface-population densities (ca. 0.01 animals/cm.2) may be unoccupied. 7. Larger animals tend to be found in deeper muds. This would lead to substrate depth influencing the age structure of populations in the field. 8. Limitations imposed by the shape and size of the burrow, rather than animal size in itself, probably explain why animals avoid shallow muds and why larger animals are found in relatively deeper muds.

Contrasts in body size and growth suggest that high population density results in faster pace of life in Damaraland mole-rats (Fukomys damarensis)

2018 ◽  
Vol 96 (8) ◽  
pp. 920-927 ◽  
Author(s):  
K.T. Finn ◽  
D.M. Parker ◽  
N.C. Bennett ◽  
M. Zöttl
Keyword(s):  
Body Size ◽  
Population Density ◽  
Litter Size ◽  
Group Size ◽  
Growth Rates ◽  
High Population ◽  
Low Density ◽  
High Population Density ◽  
Population Densities ◽  
Study Sites

We studied the correlates of population density and body size, growth rates, litter size, and group size in Damaraland mole-rats (Fukomys damarensis (Ogilby, 1838)) at two study sites with contrasting population densities. Group size, litter size, and the probability of recapture were independent of study site. However, body size differed between the two study sites, suggesting that population density may affect life-history traits in social mole-rats. At the low-density site (0.13 groups/ha), individuals were significantly larger and subordinate males showed higher growth rates than at the high-density site (0.41 groups/ha), which may indicate that high population density in subterranean rodents enhances pace of life. The larger size of nonreproductive individuals at the low-density site could adapt individuals at lower population densities to larger dispersal distances.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

Population Densities Allowed Around Dutch SEVESO Establishments

2000 ◽  
Author(s):  
G. M. H. Laheij ◽  
B. J. M. Ale ◽  
J. G. Post
Keyword(s):  
Population Density ◽  
The Netherlands ◽  
Individual Risk ◽  
Population Densities ◽  
Planning Policy ◽  
Relative Contribution ◽  
Societal Risk ◽  
Dangerous Substances ◽  
The Individual ◽  
Uniform Population

Abstract In the Netherlands, the individual risk and societal risk are used in efforts to reduce the number of people exposed to the effect of an accident at an establishment with dangerous substances. To facilitate the societal risk planning policy an investigation was carried out for the Dutch SEVESO establishments to investigate the possibility of determining a generic uniform population density for the zone between the individual risk contours of 10−5 and 10−6 per year. The indicative limit for the societal risk at this density was not to be exceeded. Also there was to be enough space left for a significantly higher population density outside the individual risk contour of 10−6 per year. The RORISC methodology and the actual data for the 124 Dutch SEVESO establishments were used to determine the generic uniform population density. Based on the data available it can be concluded that the maximum allowed uniform population density in the zone between the individual risk contours of 10−5 and 10−6 per year is lower than one person per hectare. At this density there is no space left for a higher population density outside the individual risk contour of 10−6 per year. For uniform population densities the relative contribution to the societal risk has been found significant up to the individual risk contour of 10−7 per year.

Studies on some sources of variation in carrot root weight

1981 ◽  
Vol 96 (3) ◽  
pp. 549-556 ◽  
Author(s):  
P. J. Salter ◽  
I. E. Currah ◽  
Jane R. Fellows
Keyword(s):  
Population Density ◽  
Seedling Emergence ◽  
Size Variation ◽  
Root Weight ◽  
Low Density ◽  
Plant Variation ◽  
Sowing Depth ◽  
Seedling Size ◽  
Weight Variation ◽  
Root Size

SUMMARYFive investigations were carried out to determine the magnitude of root-size variation within crops of cv. Chantenay Supreme grown under competitive and non-competitive conditions, and to study possible sources of inter-plant variation.In the first experiment root-size variation from crops grown at a high population density (245 plants/m2) and at a low density (25 plants/m2) were compared over a 21-week period from sowing. The c.v.s of root weight were always higher from the high density than from the low density over the harvesting period from 11 to 21 weeks after sowing, and ranged from 74 to 94% and from 50 to 63%, respectively. A second study showed that even with a very low population density (3 plants/m2) the c.v. of root weight at harvest was 58%. The third study showed that 40% of the root weight variation was accounted for by the time of seedling emergence. The results of a pot experiment indicated that when the size of seed, sowing depth, rooting medium and time of seedling emergence were made as uniform as possible, a very uniform population of roots was produced with a c.v. of root weight of 32%. In the final field experiment when time of seedling emergence, seed size and spatial distribution of the plants were the experimental variables, the results confirmed the importance of variability in time of seedling emergence and seedling size in creating variation at an early stage of growth.The results of these studies indicate that competition per se was not a prime source of variation in root size but magnified any initial variation within the crop at the time of seedling establishment. The importance of this early establishment phase in determining the spread of root-size distribution within a crop is discussed together with the factors which influence the time of seedling emergence and seedling size.

scholarly journals Effects of population density on cauliflower crop (Brassica oleracea L. var. botrytis)

1981 ◽  
Vol 38 (1) ◽  
pp. 1-10
Author(s):  
Keigo Minami ◽  
Ricardo Victoria Fº
Keyword(s):  
Population Density ◽  
Brassica Oleracea ◽  
Plant Population ◽  
Population Densities ◽  
Plant Population Density ◽  
Brassica Oleracea L ◽  
Quality Weight

An experiment was carried out to study the effects of the following population densities cauliflowers (plants per ha): 20,833 (0.60 m x 0.80 m), 25,641 (0.60 m x 0.65 m), ....37.037 (0.60 m x 0.45 m) , 55.555 (.0.60 m x 0.30 m), and 111,111 (0,60 m x 0,15 m) ; variety Snow ball. It was concluded that the effects of plant population density are greater on curd quality (weight and size) than on production per ha. The best plant population density to produce cauliflowers curd for Brazil market is from 20,000 to 25,000 plants/ha while for mini-curd is above 55,000 plants/ha.

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