Optimum plant population densities for lupin (Lupinus angustifolius L.) in the wheatbelt of Western Australia

1994 ◽  
Vol 34 (4) ◽  
pp. 491 ◽  
Author(s):  
RJ French ◽  
K McCarthy ◽  
WL Smart
Keyword(s):  
Western Australia ◽  
Plant Population ◽  
Lupinus Angustifolius ◽  
Yield Potential ◽  
Asymptotic Model ◽  
Population Densities ◽  
Data Set ◽  
Optimum Density ◽  
Wide Range ◽  
The Relationship

Lupin (Lupinus angustifolius L.) seed yields at various plant population densities were studied in 33 separate experiments throughout the wheatbelt of Western Australia between 1987 and 1990. The experiments were designed to test the hypotheses that optimum plant population densities for lupins vary between environments and between cultivars. Another objective was the development of a framework for sowing rate recommendations from a large data set derived from sowing rate experiments. Two types of equation were fitted to each data set by nonlinear regression: one described an asymptotic response, the other a response where yield reached a maximum but declined at higher densities. The second type of equation was used to describe a data set if the residual mean square was significantly lower than for the asymptotic equation. In all, 122 individual responses were fitted, of these only 13 were not adequately described by the asymptotic model. Optimum density was chosen according to an economic criterion (when marginal revenue from an increase in plant population density equalled marginal cost). This was equivalent to choosing the point where the slope of the response curve was 0.004 t.m2/ha.plant (equivalent to 0.4 g/plant). Optimum density ranged from 14 to 138 plants/m2 and was linearly related to yield potential, which we defined as either the asymptotic yield value, or the maximum yield for responses that did not approach an asymptote. Yield potential ranged from 0.13 to 4.1 t/ha. The relationship between optimum density and yield potential was the same for cvv. Danja, Gungurru, and Yorrel, and for a reduced branching breeding line (75A/329). It was also the same on soils classified as good or poor for lupins. We suggest that the relationship between optimum density and yield potential will be useful in determining target plant densities for lupins under a wide range of conditions in Western Australia, and that the techniques should prove useful in producing recommendations from density experiments in other agricultural regions.

Plant density response and optimum crop densities for canola (Brassica napus L.) in Western Australia

2016 ◽  
Vol 67 (4) ◽  
pp. 397 ◽  
Author(s):  
R. J. French ◽  
M. Seymour ◽  
R. S. Malik
Keyword(s):  
Brassica Napus ◽  
Western Australia ◽  
Maximum Yield ◽  
Yield Potential ◽  
High Yield ◽  
Yield Response ◽  
Asymptotic Model ◽  
Brassica Napus L ◽  
Optimum Density ◽  
Crop Density

In 24 experiments conducted across a range of agricultural environments in Western Australia between 2010 and 2014 canola (Brassica napus L.) grain yield response to crop density was adequately described by an asymptotic model (where yield approaches but never quite reaches a ceiling at very high density) in 101 out of 112 individual responses; in the other 11 yield reached a maximum and declined slightly at higher densities. Seed oil was more likely to increase than decrease with increasing density but the effect was always small; less than 1% oil over the range of densities tested. Increasing density also suppressed annual ryegrass (Lolium rigidum (L.) Gaud.) head numbers in six experiments where it was measured, especially at densities below 20 plants/m². Economic optimum densities ranged from 7 to 180 plants/m², with a median of 32.2. Mean optima in low and medium rainfall zones (growing season rainfall <300 mm) were about 25, 30, and 75 plants/m² respectively for glyphosate-tolerant (Roundup Ready), hybrid triazine-tolerant (TT), and open-pollinated TT cultivars, assuming open-pollinated TT cultivars were grown from farm-saved seed. There was little difference between optimum densities for hybrid and open-pollinated glyphosate-tolerant cultivars, and optima in the high rainfall zone were about 10 plants/m² higher than in low and medium rainfall zones. Yield at optimum density was greater than 90% of maximum yield in 74% of cases. The economic penalty for not achieving the optimum density with hybrids was usually small if the deviation was less than 10 plants/m², and with open-pollinated TT cultivars was small even 50-60 plants/m² below the optimum. The penalty was usually greater for deviations below than above the optimum in medium and high yield potential environments (yield potential >1000 kg/ha). Predicted optima were more sensitive to seed cost and field establishment (the proportion of viable seeds that become established) than grain price or seed size over the range of values expected in Western Australian agriculture. Field establishment varied from 0.3 to 1 and was higher at low target densities and for hybrid compared with open-pollinated cultivars, with a median of 0.585 at a target density of 40 plants/m². We identified improving field establishment of canola as an important research priority.

Yield potential of reduced-branching lupins (Lupinus angustifolius) on sandy soils in a short season environment

1986 ◽  
Vol 37 (6) ◽  
pp. 611 ◽  
Author(s):  
J Hamblin ◽  
R Delane ◽  
A Bishop ◽  
J Gladstones
Keyword(s):  
Sandy Soils ◽  
Lupinus Angustifolius ◽  
Water Holding Capacity ◽  
Yield Potential ◽  
Wide Range ◽  
Short Season ◽  
Water Holding

Experiments that compare the yield potential of reduced branching narrow-leafed lupins with that of the conventional branched types show that on sandy soils of low water-holding capacity in a short season environment, reduced-branching lupins have a higher yield potential than current cultivars. The yield potential of these new types appears to be maintained over a wide range of environmental yield levels. L. angustifolius was higher yielding than L. albus or L. cosentinii genotypes of similar maturity.

Comparative Response of Conventional and Quality Protein Maize Hybrids to High Population Densities in the Southern Guinea Savanna of Nigeria

2013 ◽  
Vol 2 (1) ◽  
Author(s):  
O B Bello
Keyword(s):  
Grain Yield ◽  
Plant Density ◽  
Plant Population ◽  
Yield Potential ◽  
High Yield ◽  
Quality Protein Maize ◽  
Population Densities ◽  
Higher Plant ◽  
Guinea Savanna ◽  
Plant Densities

Optimum plant population is very important in enhancing high and stable grain yield especially in quality protein maize (QPM) production. A field trial was therefore conducted to compare the performance of six hybrids (three each of QPM and normal endosperm) at three population densities using a split-plot design at the sub-station of the Lower Niger River Basin Development Authority, Oke-Oyi, in the southern Guinea savanna zone of Nigeria during the 2010 and 2011 cropping seasons. Plant population -1 densities (53,333, 66,666, and 88,888 plants ha ) constituted the main plots and the six hybrids were assigned to the subplots, replicated three times. Our results showed a differential response of maize -1 hybrids to high densities, with plant populations above 53,333 plants ha reduced grain yield, and this is more pronounced in QPM than normal endosperm hybrids. This is contrary to the results observed in many other countries. This might be that the hybrids were selected in low yield potential area at low plant densities, and hence not tolerant to plant density stress. It may also be due to low yield potential of the experimental site, which does not allow yield increases at high plant densities. Though normal endosperm hybrids 0103-11 and 0103-15 as well as QPM Dada-ba were superior for grain yield among -1 the hybrids at 53,333 plants ha , hybrid 0103-11 was most outstanding. Therefore, genetic improvement of QPM and normal endosperm hybrids for superior stress tolerance and high yield could be enhanced by selection at higher plant population densities.

scholarly journals Persistence of dry matter yield among New Zealand perennial ryegrass (Lolium perenne L.) cultivars: insights from a long-term data set

2015 ◽  
Vol 77 ◽  
pp. 177-184 ◽  
Author(s):  
D.F. Chapman ◽  
P.D. Muir ◽  
M.J. Faville
Keyword(s):  
New Zealand ◽  
Perennial Ryegrass ◽  
Dry Matter ◽  
Heading Date ◽  
Early Years ◽  
Grass Species ◽  
Data Set ◽  
High Performing ◽  
Wide Range ◽  
The Relationship

Persistence of herbage yield is an important productivity trait of grass species and cultivars in New Zealand pastures. However, relatively little is known about genetic variation in this trait, principally because few studies comparing yield have continued beyond 3 years. This paper reports results from a comparison of 25 perennial ryegrass cultivars representing a wide range of functional types and genetic backgrounds conducted under sheep grazing in a summer-dry environment. Dry matter (DM) yield was measured for the first 3 years after sowing, then again in years seven and eight post-sowing, and in year ten post-sowing. Endophyte DNA fingerprinting conducted mid-way through year seven confirmed that, with one exception, ryegrass populations remained true-to-type in the cultivars sown with novel endophyte strains. The cultivar effect on DM yield was statistically significant in all measurement periods. Differences in yields among cultivars in years seven and eight were significantly and positively correlated with yield differences in years one to three (r=0.685 to 0.831 depending on which year contrasts were used). Thus, high-performing cultivars in the early years of the trial were also generally highperforming cultivars in years seven and eight, and vice-versa, indicating a high degree of yield stability in perennial ryegrass cultivars. Yield differences did not appear to be related to differences in cultivar heading date, ploidy, endophyte status, or genetic background. The relationship between yield in year ten and yields in years one to three was much weaker (r=0.392) than the relationship in years seven and eight. Possible reasons for this are discussed. Keywords: Perennial ryegrass; traits; persistence

A comparison of the relationship between measured acoustic response and porosity in carbonates across different geologic periods, depositional basins, and with variable mineral composition

2018 ◽  
Vol 6 (2) ◽  
pp. T245-T256
Author(s):  
Beth Vanden Berg ◽  
Christophe Nussbaumer ◽  
Amy Noack ◽  
John Thornton ◽  
Ralf J. Weger ◽  
...  
Keyword(s):  
Carbonate Platform ◽  
Order Estimate ◽  
Michigan Basin ◽  
Limited Data ◽  
Data Set ◽  
Paradox Basin ◽  
Great Bahama Bank ◽  
Wide Range ◽  
Basic Relationship ◽  
The Relationship

Recent work has shown that there is a predictable inverse relationship between laboratory-measured sonic velocity response and porosity in carbonates, which can be reasonably approximated using the empirical Wyllie time-average equation (WTA). The relationship was initially identified in late Cretaceous to Cenozoic age samples collected from the Great Bahama Bank and the Maiella Platform, an exhumed Cretaceous carbonate platform in Italy. We have compared older carbonate samples from different basins and different geologic ages to determine the applicability of this relationship and subsequent correlations to key petrophysical properties to other carbonate basins and other geologic time periods. The data set used for the comparison shows this relationship to be relatively consistent in other depositional basins (Michigan Basin, Paradox Basin) and with samples from older geologic periods (Pennsylvanian, Ordovician, and Mississippian). However, this basic relationship is also observed to vary significantly within a reservoir system and within a depositional basin in samples from different geologic periods (e.g., Silurian- versus Ordovician-age rocks in the Michigan Basin). Although the empirical WTA can generally be applied as a first-order estimate across a wide range of sample ages in carbonates, limited data suggest the relationship between velocity and porosity to be moderately more complex. For instance, in unconventional carbonate reservoirs characterized by predominantly micro- to nanoscale porosity, it is observed that the WTA should be applied as an upper data boundary. In addition, this study has shown that the relationship to the dominant pore type is less direct than in a macropore system in which it can be assumed that the dominant pore type also has the greatest effect on the effective permeability.

Response of kabuli chickpea (Cicer arietinum L.) to sowing rate in Mediterranean-type environments of south-western Australia

2003 ◽  
Vol 43 (1) ◽  
pp. 87 ◽  
Author(s):  
K. L. Regan ◽  
K. H. M. Siddique ◽  
L. D. Martin
Keyword(s):  
Seed Yield ◽  
Western Australia ◽  
Seed Weight ◽  
Plant Density ◽  
Unit Area ◽  
Mechanical Damage ◽  
Strong Relationship ◽  
Yield Potential ◽  
Asymptotic Model ◽  
Plant Densities

The effect of sowing rate (60–320 kg/ha) on the growth and seed yield of kabuli chickpea (cv. Kaniva) was assessed at 11 sites for 4 seasons in the cropping regions of south-western Australia. The economic optimum plant density and yield potential were estimated using an asymptotic model fitted to the data and calculating the sowing rate above which the cost of additional seed was equivalent to the revenue that could be achieved from the extra seed yield produced, assuming a 10 and 50% opportunity cost. On average for all sites and seasons, plant densities ranged from 10 plants/m2 when sown at 60 kg/ha to 43�plants/m2 when sown at 320 kg/ha. Assuming a mean seed weight of 400 mg and a germination of 80%, then on average 75% of viable seeds sown (or 60% of sown seeds) established as plants. The poor establishment rates are thought to be associated with reduced viability caused by mechanical damage, storage conditions, fungal infection in the soil, and unfavourable seed bed moisture and temperatures. In general, there was a positive relationship between sowing rate and seed yield. Seed yield increases at higher sowing rates were mainly associated with the greater number of plants per unit area. There were fewer pods per plant at higher sowing rates, but there were more pods per unit area. Changing the sowing rate had little effect on mean seed weight and the number of seeds per pod. The economic optimum plant density varied from 8 to 68 plants/m2, depending on the location, but the mean (27�plants/m2) was within the range currently recommended in southern Australia (25–35 plants/m2). Due to the low establishment rates observed in this study, we estimate a sowing rate greater (160–185 kg/ha) than currently suggested (110–160 kg/ha) to achieve this density. There was a strong relationship between economic optimum plant density and seed yield potential (r2 = 0.66, P<0.01), which allows an estimation of the most profitable sowing rate, depending on the seed yield potential of the site. For most crops yielding about 1.0 t/ha in southern Australia, a plant density of 25 plants/m2 is most profitable, while in higher-yielding situations (>1.5 t/ha) plant densities >35�plants/m2 will produce the most profit.

Optimum plant density of desi chickpea (Cicer arietinum L.) increases with increasing yield potential in south-western Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 1017 ◽  
Author(s):  
R . J. Jettner ◽  
S. P. Loss ◽  
K. H. M. Siddique ◽  
R. J. French
Keyword(s):  
Seed Yield ◽  
Western Australia ◽  
Field Experiments ◽  
Plant Density ◽  
Yield Potential ◽  
Asymptotic Model ◽  
Physical Damage ◽  
Plant Populations ◽  
Plant Seed ◽  
Plant Densities

The response of chickpea (cv. Tyson) seed yield to sowing rate (30–180 kg/ha) was examined in 18 field experiments across 3 years in south-western Australia. The economic optimum plant density was estimated at each site by fitting an asymptotic model to the data and calculating the point where the cost of extra seed equalled the return from additional seed yield, allowing a 10% opportunity cost for the extra investment. When averaged across all sites and seasons, plant densities varied from 14 plants/m2 when sown at 30 kg/ha to 84 plants/m2 when sown at 180 kg/ha. Therefore, only about 54% of seeds sown established into viable plants, even though the germination test of the seed was about 80%. The poor establishment rate is thought to be mainly due to physical damage to the seed during transport and sowing, as well as unfavourable seed-bed moisture and temperature conditions. At most experimental sites the seed yield of desi chickpea responded positively to an increase in sowing rate up to about 120 kg/ha. Increased yields at high sowing rate can be directly attributed to large plant populations. Although in many cases the number of pods per plant, seed size, and harvest index were reduced at high plant populations, increased plant density compensated for these effects and seed yield tended to increase. There was a good relationship between economic optimum plant density and yield potential derived in this study (r2 = 0.497, P< 0.001) and this improves the ability of desi chickpea producers to select the most profitable sowing rate, depending upon their yield potential. These results suggest that the optimum plant density is 50 plants/m2 for most chickpea crops in south-western Australia yielding about 1.0 t/ha, whereas in high-yielding situations (>1.5 t/ha), plant densities >70 plants/m2 produce the most profit. Although not observed in these experiments, high plant densities can exacerbate fungal diseases, and hence, reduced plant densities are desirable in disease-prone situations. Differences in sowing rate responses may be expected between Tyson and new large-seeded cultivars such as Heera and Sona, which have longer branches and more open canopy, or kabuli types, and this deserves further investigation.

Determinants of species abundance in the Quaternary vertebrate fossil record

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 537-546 ◽  
Author(s):  
Samuel T. Turvey ◽  
Tim M. Blackburn
Keyword(s):  
Body Mass ◽  
Species Abundance ◽  
Ecological Factors ◽  
General Applicability ◽  
Data Set ◽  
Terrestrial Vertebrate ◽  
Wide Range ◽  
Holocene Record ◽  
Independent Calibration ◽  
The Relationship

Species abundance data are of vital importance in paleontology, but fossil accumulations invariably represent a biased subset of original source communities. Efforts to quantify taphonomic biases are typically prevented by a lack of independent data on the ecological composition of prehistoric faunas. However, analysis of the continental Holocene record can provide a rare opportunity for independent calibration of fossil abundance patterns. We analyzed a comprehensive data set available for the Holocene avifauna of Sweden to investigate the relationship between species abundance in the recent fossil and zooarchaeological records and in prehistoric source communities, and to characterize the importance of different ecological factors in determining terrestrial vertebrate fossil abundances. The number of assemblages in which species occurred was compared with modern-day species abundance, annual residence, body mass, and ecological realm. Modern-day abundance is only one of several significant predictors of fossil abundance; the strongest predictor is body mass, and Holocene species abundance can be interpreted as a measure of species abundance in source communities for a given size class only. Our study represents one of the only direct attempts to quantify species abundance biases between fossil faunas and source communities, and has general applicability for a wide range of terrestrial vertebrate faunas.

scholarly journals The relationship between self-employment and unemployment in the long-run

2016 ◽  
Vol 43 (3) ◽  
pp. 358-379 ◽  
Author(s):  
George Saridakis ◽  
Miguel Angel Mendoza ◽  
Rebeca I. Muñoz Torres ◽  
Jane Glover
Keyword(s):  
Design Methodology ◽  
Structural Breaks ◽  
Panel Cointegration ◽  
Data Set ◽  
Content Type ◽  
Self Employment ◽  
Long Run ◽  
Wide Range ◽  
Short Run ◽  
The Relationship

Purpose – Although a lot of research has been done on the link between self-employment and unemployment, often focusing on the short-run of the relationship, the long-run association between the two variables has not received adequate attention. The paper aims to discuss these issues. Design/methodology/approach – In this paper the authors examine the long-run relationship between self-employment and unemployment using panel cointegration methods allowing for structural breaks and covering a wide range of European OECD countries using the COMPENDIA data set over the period 1990-2011. Findings – The findings indicate that a long-run relationship between self-employment and unemployment exist in the panel, but the cointegrating coefficients are unstable. Originality/value – The estimates finds positive and statistically significant long-run association between self-employment and unemployment exists for more than 50 per cent of the countries included in the sample after the break. For the rest of the countries the authors find either negative or statistically insignificant association.

scholarly journals Definition of Optimal Maize Seeding Rates Based on the Potential Yield of Management Zones

Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 911
Author(s):  
Adriano Adelcino Anselmi ◽  
José Paulo Molin ◽  
Helizani Couto Bazame ◽  
Lucas de Paula Corrêdo
Keyword(s):  
Low Cost ◽  
Plant Population ◽  
Yield Potential ◽  
Specific Yield ◽  
Population Densities ◽  
Potential Yield ◽  
Site Specific ◽  
Management Zones ◽  
Soil Attributes ◽  
Maize Hybrids

The decision on crop population density should be a function of biotic and abiotic field parameters and optimize the site-specific yield potential, which can be a real challenge for farmers. The objective of this study was to investigate the yield of maize hybrids subjected to variable rate seeding (VRS) and in differentiated management zones (MZs). The experiment was conducted between 2013 and 2015 in a commercial field in the Central-West region of Brazil. First, MZ were delineated using the K-means algorithm with layers involving soil electrical conductivity, yield maps from previous years, and elevation. Seven maize hybrids at five seeding rates were evaluated in the context of each MZ and the cause-and-effect relationship with soil attributes was investigated. Optimal yields were obtained for crop population densities between 70,000 plants ha−1 and 80,000 plants ha−1. Hybrids which perform well under higher densities are key in achieving positive results using VRS. The plant population densities that resulted in maximum yields were obtained for densities at least 27% higher than the recommended seeding rates. The yield variance between MZs can be explained by the variance in soil attributes, while the yield variance within MZs can be explained by the variance in plant population densities. The study shows that on-farm experimentation can be key for obtaining information concerning yield potential. The management by VRS in different MZs is a low-cost technique that can reduce input application costs and optimize yield according to the site-specific potential of the field.

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