Explain Differences In Growth Research Articles

Understanding the factors influencing the growth of Zelkova abelicea in browsing exclosures

The growth of Zelkova abelicea (Lam.) Boiss. (Ulmaceae), a tree species endemic to the island of Crete (Greece), was studied within 31 fenced plots protected from browsing during three years after fencing across the entire distribution range of the species. Potential geographic, edaphic, climatic and physiognomic factors that could influence shoot elongation and height increase were investigated for each plot. We found that trees grew twice as much within the same period of time in western and central Crete compared to trees from eastern Crete. In addition, taller trees grew more than shorter individuals. Although some variation was found within the soil parameters, and particularly sites situated on slopes were distinguishable from sites situated in flat dolines, none of the soil parameters was found to be significant in explaining growth differences amongst Z. abelicea trees of different mountain ranges. Precipitation and temperature were interpolated for each plot from an existing network of 49 weather stations on Crete. Our analyses showed that the plots were distributed along a longitudinal, westwards increasing gradient in precipitation as well as along an altitudinal gradient in temperature. Our analyses revealed that geographical position on the island, precipitation in June and initial tree height were significant in explaining spatial differences in Z. abelicea growth. Our results underline the importance of spring and early summer climatic conditions in determining Z. abelicea growth and highlight differences throughout the island.

Do biomass partitioning and growth efficiency contribute to growth heterosis in inter-specific hybrid larchLarix x eurolepis?

AbstractHybrid larch (Larix decidua x L.kaempferi) is a fast growing species with high potential for reforestation outside the native range of European larch. Its superiority over its parents is well documented but still today little is known about the genetic background of heterosis and even less about the physiological mechanisms supporting it. In this paper, we hypothesize that a different allocation of biomass and/or growth efficiency could explain growth differences between larch species. To examine heterosis sensu stricto, we used a subset of progeny from an intra−/inter-specific diallel-mating design represented by connected pedigrees from the three species (Hybrid larch, European larch and Japanese larch). Six years after planting, we harvested the trees, excavated roots and measured dry weights of above- and belowground parts. The best allometric relationships were determined for predicting the biomass of each compartment. Heterosis for stem volume exceeded 108 per cent and 81 per cent for total tree biomass over mid-parent values. Hybrid superiority was visible for all biomass compartments and particularly for needles and branches, so that aboveground biomass heterosis reached 2.5 times that for the roots. In addition to a greater biomass, the hybrid benefited from a modified allocation of biomass with a slightly higher proportion of branch and needle biomasses and a reduced proportion of root biomass. Hybrid and European larches had a significantly greater growth efficiency than Japanese larch. Whereas the differential of productivity between European and Japanese larch did not increase with size, it greatly increased for hybrids with fine root mass increase. A heavier crown, a reduced proportion of root biomass and greater root efficiency in hybrid larch should enhance photosynthesis and reduce root respiration cost, providing more carbon-based resources for use in stem wood production. Implications for breeding are briefly discussed.

Canopy Size and Light Use Efficiency Explain Growth Differences between Lettuce and Mizuna in Vertical Farms.

Vertical farming is increasingly popular due to high yields obtained from a small land area. However, the energy cost associated with lighting of vertical farms is high. To reduce this cost, more energy efficient (biomass/energy use) crops are required. To understand how efficiently crops use light energy to produce biomass, we determined the morphological and physiological differences between mizuna (Brassica rapa var. japonica) and lettuce (Lactuca sativa ‘Green Salad Bowl’). To do so, we measured the projected canopy size (PCS, a morphological measure) of the plants throughout the growing cycle to determine the total amount of incident light the plants received. Total incident light was used together with the final dry weight to calculate the light use efficiency (LUE, g of dry weight/mol of incident light), a physiological measure. Plants were grown under six photosynthetic photon flux densities (PPFD), from 50 to 425 µmol m−2 s−1, for 16 h d−1. Mizuna and lettuce were harvested 27 and 28 days after seeding, respectively. Mizuna had greater dry weight than lettuce (p < 0.0001), especially at higher PPFDs (PPFD ≥ 125 µmol m−2 s−1), partly because of differences in the projected canopy size (PCS). Mizuna had greater PCS than lettuce at PPFDs ≥ 125 µmol m−2 s−1 and therefore, the total incident light over the growing period was also greater. Mizuna also had a higher LUE than lettuce at all six PPFDs. This difference in LUE was associated with higher chlorophyll content index and higher quantum yield of photosystem II in mizuna. The combined effects of these two factors resulted in higher photosynthetic rates in mizuna than in lettuce (p = 0.01). In conclusion, the faster growth of mizuna is the result of both a larger PCS and higher LUE compared to lettuce. Understanding the basic determinants of crop growth is important when screening for rapidly growing crops and increasing the efficiency of vertical farms.

Explaining growth differences across firms: The interplay between innovation and management practices

This paper provides first empirical evidence of the joint effects that innovation strategies and human resource management practices exert on firm growth. It shows that investing in technology and implementing performance-based pay policies are both positively associated with a significant turnover, employment and labor productivity growth premium. However, their joint adoption does not necessarily sum the two effects. In particular, for firms strongly relying on R&D as a lever for product and process upgrading, the estimated effect of having in place monetary incentive mechanisms is null or even negative. Job enlargement and employee empowerment policies, instead, are not found to directly impact on growth, independently of the innovation strategy pursued by firms.

A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda

Previous work indicates that Pinus taeda L. grows faster and has a higher carrying capacity when grown outside its native range. We were interested in examining the hypotheses that growth, light use efficiency (volume growth and absorbed photosynthetically active radiation relationship, LUE) and volume growth per unit heat sum is the same for native and exotic plantations. To test these hypotheses, we installed a common garden experiment where the same six genetic entries of P. taeda (four clonal varieties, one open pollinated family and one control mass pollinated family) were planted at three densities (618, 1235, and 1853 stems ha−1) with three or four replications at three sites (Virginia (VA), and North Carolina (NC) in the United States and Paraná State in Brazil (BR)). The VA and BR sites were outside the native range of P. taeda. After five years of growth, the BR site had larger trees and stand scale basal area and volume were increasing faster than the other sites. Site did not affect LUE but density and genetic entry did. The sites were at different latitudes but the average photosynthetically active radiation at the top of the canopy was similar for the years when all sites were operational, likely because the BR site receives more rain annually and the cloudiness associated with the rain may have reduced available light. We estimated an hourly heat sum where the daytime temperature was between 5 and 38 °C, hours where vapor pressure deficit exceeded 1.5 kPa and days following nights where nighttime temperatures were less than 0 °C were excluded. Site was significant for the cumulative volume and heat sum relationship, for a given level of cumulative degree hours the sites ranked BR > VA > NC in cumulative volume. The different growth per unit of degree hours for each site indicated that something other than the heat sum was causing the observed difference in growth. Other factors including respiration and extreme climatic conditions may contribute to growth differences per unit degree hour and including these differences in the analysis would require a more detailed modeling effort to examine. The sites used in this study are ideally suited to continue testing additional hypotheses to explain the different growth between native and exotic P. taeda plantations because they have the same genotypes at all sites and consequently eliminate differences in genetics as a potential explanation for observed growth differences.

Explaining Growth Differences Across Firms: The Interplay between Innovation and Management Practices

This paper provides first empirical evidence of the joint effects that innovation strategies and human resource management practices exert on firm growth. By exploiting unique information from a large sample of Italian manufacturing firms in the very recent years, it shows that investing in technology and implementing performance-based pay policies are both positively associated with a significant turnover, employment and labor productivity growth premium. However, their joint adoption does not necessarily sum the two effects. In particular, performance-based rewards boost the growth of non innovating firms and of firms pursuing relatively simple innovation strategies, centered around the acquisition of new machinery, equipment and software. For firms strongly relying on R&D as an additional lever for product and process upgrading, the estimated effect of having in place such incentive mechanisms is null or even negative.

Differential gene expression and SNP association between fast- and slow-growing turbot (Scophthalmus maximus)

Growth is among the most important traits for animal breeding. Understanding the mechanisms underlying growth differences between individuals can contribute to improving growth rates through more efficient breeding schemes. Here, we report a transcriptomic study in muscle and brain of fast- and slow-growing turbot (Scophthalmus maximus), a relevant flatfish in European and Asian aquaculture. Gene expression and allelic association between the two groups were explored. Up-regulation of the anaerobic glycolytic pathway in the muscle of fast-growing fish was observed, indicating a higher metabolic rate of white muscle. Brain expression differences were smaller and not associated with major growth-related genes, but with regulation of feeding-related sensory pathways. Further, SNP variants showing frequency differences between fast- and slow-growing fish pointed to genomic regions likely involved in growth regulation, and three of them were individually validated through SNP typing. Although different mechanisms appear to explain growth differences among families, general mechanisms seem also to be involved, and thus, results provide a set of useful candidate genes and markers to be evaluated for more efficient growth breeding programs and to perform comparative genomic studies of growth in fish and vertebrates.

Long chain polyunsaturated fatty acid supplementation in infancy increases length- and weight-for-age but not BMI to 6 years when controlling for effects of maternal smoking

Long chain polyunsaturated fatty acids (LCPUFA) are added to infant formula but their effect on long-term growth of children is under studied. We evaluated the effects of feeding LCPUFA-supplemented formula (n=54) compared to control formula (n=15) throughout infancy on growth from birth-6 years. Growth was described using separate models developed with the MIXED procedure of SAS® that included maternal smoking history and gender. Compared to children fed control formula, children who consumed LCPUFA supplemented formula had higher length-/stature-/and weight-for-age percentiles but not body mass index (BMI) percentile from birth to 6 years. Maternal smoking predicted lower stature (2–6 years), higher weight-for-length (birth-18 months) and BMI percentile (2–6 years) independent of LCPUFA effects. Gender interacted with the effect of LCPUFA on stature, and the relationship between smoking and BMI, with a larger effect for boys. Energy intake did not explain growth differences. A relatively small control sample is a limitation.

Fiscal Policy And Economic Growth: The Effect of Fiscal Volatility

&lt;p class="MsoNormal" style="text-align: justify; margin: 0in 0.6in 0pt 0.75in;"&gt;&lt;span style="font-family: Times New Roman; font-size: x-small;"&gt;This paper investigates the effect of fiscal policy on economic growth.&lt;span style="mso-spacerun: yes;"&gt;&amp;nbsp; &lt;/span&gt;Unlike the literature on growth that emphasizes the level and the nature of fiscal parameters, this paper focuses on the effect of fiscal volatility on economic growth.&lt;span style="mso-spacerun: yes;"&gt;&amp;nbsp; &lt;/span&gt;The literature on growth ignores the micro-economic instability associated with frequent changes of fiscal policy. The empirical results of this paper indicate that the effect of fiscal policy on economic growth is inconclusive.&lt;span style="mso-spacerun: yes;"&gt;&amp;nbsp; &lt;/span&gt;Most of the fiscal policy parameters commonly used in the growth literature had failed to explain growth differences across countries.&lt;span style="mso-spacerun: yes;"&gt;&amp;nbsp; &lt;/span&gt;However, when fiscal policy instability variables are used in the growth equation, almost all of the variables are significantly and negatively correlated with economic growth.&lt;/span&gt;&lt;/p&gt;

Leaf area duration in natural range and exotic Pinus taeda

Exotic Pinus taeda L. plantations may be more productive than native ones. Several hypotheses may explain this difference; however, process models with a light-interception-driving variable cannot test these hypotheses without foliage display first being quantified in native and exotic trees. We quantified leaf area duration in North Carolina, USA (natural), and Gobernador Virasoro, Argentina (exotic), with no additional nutrients and optimum fertilizer treatments. More (60%–100%) foliage was displayed but for a shorter (∼86 fewer days) time per fascicle in the exotics than in the naturals. Study inference was limited, with only one native and one exotic site. However, while the sites were markedly different in soils, climate, resource availability, and genetics, and we observed significant differences in fascicle display and longevity, most fascicles at both sites survived two growing seasons: the one in which they were produced and the subsequent one. This robust finding indicates it would be reasonable to use two growing seasons for fascicle longevity in process modeling to test hypotheses explaining growth differences in native and exotic loblolly. Fertilization had no effect on any exotic tree parameter, but it increased natural tree fascicle number (24%) and length (30%).

First-year growth and recruitment of coastal largemouth bass (Micropterus salmoides): spatial patterns unresolved by critical periods along a salinity gradient

Although critical periods often explain first-year growth and recruitment patterns of young fishes, isolated subpopulations in spatially heterogeneous environments can be influenced by distinct factors, preventing critical periods from explaining growth and recruitment for the overall population. When we explored first-year growth and recruitment variability of largemouth bass (Micropterus salmoides) along an upstream–downstream gradient in the Mobile–Tensaw Delta, Alabama, USA, growth was consistently faster at sites closest to or within brackish habitats in 2002 and 2003, despite different abiotic conditions between years. Energetic content of food consumed by faster-growing fish, particularly those furthest downstream, was greater than that for slower-growing fish. Although the timing of the switch to piscivory did not explain growth differences, the degree of piscivory was important. Hatch date had no influence on growth differences and consequently did not affect fall condition, overwinter survival, or age-1 recruitment. Contrary to several studies in freshwater systems at this latitude, first-winter mortality was neither size-selective nor excessive, and largemouth bass continued to grow through the winter. These results demonstrate that early growth can vary substantially among subpopulations in spatially heterogeneous environments and that these differences are not necessarily explained by the same factors thought to be important for freshwater largemouth bass populations.

Institutional differences as sources of growth differences

Until recently, most studies investigating the determinants of growth failed to incorporate the importance of institutions into the empirical analysis. This paper highlights the importance of institutions on growth and development and evaluates the empirical results on the effect of institutions on growth and investment. It provides ample evidence that the institutional environment in which an economic activity takes place is an important determinant of economic growth. This paper uses alternative measures of institutional quality to capture the role of institutions in explaining growth differences across countries. When these institutional variables are incorporated into the core regression equations as additional explanatory variables in two different sample periods, both samples yield similar results. The empirical results reveal that countries with high levels of economic growth are characterized by high levels of economic freedom and judicial efficiency, low levels of corruption, effective bureaucracy, and protected private property.

Armenia: The Road to Sustained Rapid Growth-Cross-Country Evidence

This study examines the growth determinants and the economic policy challenges that Armenia faces to sustain the rapid growth of the past two years. The paper also seeks to answer the following two questions: Why has Armenia performed relatively better than other transition economies? What are the roles of macroeconomic policies and the level of financial intermediation in explaining growth differences? The paper also draws upon past cross-country experiences by estimating panel regressions on the determinants of growth to make predictions for the Armenian economy.

Armenia: The Road to Sustained Rapid Growth, Cross-Country Evidence

This study examines the growth determinants and the economic policy challenges that Armenia faces to sustain the rapid growth of the past two years. The paper also seeks to answer the following two questions: Why has Armenia performed relatively better than other transition economies? What are the roles of macroeconomic policies and the level of financial intermediation in explaining growth differences? The paper also draws upon past cross-country experiences by estimating panel regressions on the determinants of growth to make predictions for the Armenian economy.

Abscisic acid concentration, root pH and anatomy do not explain growth differences of chickpea (Cicer arietinum L.) and lupin (Lupinus angustifolius L.) on acid and alkaline soils

The ABA concentrations of leaves, roots, soils and transport fluids of chickpea and lupin plants growing in acid (pH=4.8) and alkaline (pH=8.0) soils and an acid soil with an alkaline subsoil and an alkaline soil with an acid subsoil were measured with the aim of explaining the poor growth of narrow-leafed lupins in alkaline soil. The ABA concentration in the leaves was higher in lupin than chickpea, but did not differ when the plants were grown in alkaline compared to acid soil. The ABA concentration of the roots and xylem sap of lupin did not differ significantly when grown in acid or alkaline soil. Chickpea roots and xylem sap had, however, lower ABA concentrations in acid soil. The ABA concentration in the soil solution was higher in the acid than in the alkaline soil. Roots of lupin and chickpea showed no suberization of the hypodermis or exodermis whether grown aeroponically or hydroponically and the pH of the cytoplasm did not change significantly when root cells of lupin and chickpea were exposed to external pHs of 4.8 or 8.0. The chickpea roots had greater suberization of the endodermal cells adjacent to radial xylem rays and maintained a slightly higher vacuolar pH than lupin in both acid and alkaline external media, but these small differences are insufficient to explain the reductions in lupin growth in alkaline soil.

Political instability, policy uncertainty, and economic growth: An empirical investigation

This paper elaborates upon the effect of political stability on economic growth using a novel approach. Unlike the literature on growth that emphasizes the turnover of decision makers, this paper focuses on the volatility of economic policies as the relevant indicator of stability. The literature on growth ignores the microeconomic instability associated with frequent changes of government policies. The empirical results of this paper indicate that the effect of political instability on economic growth is not conclusive. Most of the commonly used proxies for political instability have failed to explain growth differences across countries. The political instability indices have no significant effect on growth when a reasonable set of core variables is also included in the regression equation. The results also show that almost all of the policy uncertainty variables are significantly and negatively correlated with economic growth. However, the instability of economic policies has no significant impact on the accumulation of capital.

Productivity Growth Reconsidered

Productivity growth reconsidered Nicholas Crafts This paper reviews European experience in productivity advance since the war in the light of new growth theory, rent-seeking and catch-up explanations of growth performance. The evidence is analysed using a mixture of regression analysis, case studies and a modified form of growth accounting. Policy implications are derived relating both to Western and Eastern Europe in the 1990s. It is argued that the concentration of new growth theory on factor accumulation proves of only limited use in explaining growth differences within the OECD and that it is crucial to investigate rent-seeking and institutional differences as well In particular, it is important not to exaggerate the role of physical investment in explaining why growth rates differ. Similarly, it is stressed that catching-up of advanced countries by followers is by no means an automatic process and has proceeded unevenly. Recent ideas in growth economics are shown to require urgent revision of traditional growth accounting analysis. Supply-side policy including institutional design is seen as the key to rapid catch-up but political constraints in this area are highlighted. Accordingly, the policy recommendations in the paper emphasize the role of pre-commitment through international agreements as an important growth-promoting factor in 1990s Europe.

A comparison of the personality type dimensions of the 1987 Inc. 500 company founders/CEOs with those of slower-growth firms

A popular misconception holds that most new businesses experience similar growth stages of start-up, rapid growth, maturity, and decline. Yet, business statistics show that only a small number of firms grow into large organizations. A few experience some growth, but the majority have such small growth that they provide only a marginal income to the founder. While market conditions impact on the growth of the firm, they do not explain growth differences when they occur under similar market conditions. In this paper, the authors have compared psychological type preferences of founders/CEOs of fast-growth firms with those of slow-growth firms under the assumption that differences in psychological preferences, as they relate to gathering, assimilating, and processing information, would have an impact on the strategic or growth orientation of the firm. The results are based on the administration of the Myers-Briggs Type Indicator to the founders/cofounders of 143 firms included in the 1987 Inc. 500 list of the fastest-growing private companies in the United States and the comparison of these results with those of an earlier study of 150 founders/CEOs of successful, yet slower growing firms. The primary personality traits under consideration were an individual's preferred method of gathering information from the environment, making decisions, and drawing conclusions from the information. The results indicate that founders of rapid-growth firms have psychological preferences that are significantly different from those of their slower-growth counterparts. Growth oriented founders prefer an intuitive approach or consideration of future possibilities when gathering information, and a thinking or planned and organized approach to drawing conclusions. These preferences represent those facets most frequently used in strategic or growth planning. Investors in new firms that place importance on the capabilities and orientations of the management team as an evaluation criteria are currently limited to consideration of past experiences. An awareness of the management team's experiences can provide an indication of management ability, but unless their experience involves management of growth, the information related to growth propensities or orientations is limited. A measure of a person's preferences in gathering, assimilating, and processing information can indicate their desires for strategic and/or growth planning. Hence, investors may have another tool that can be used in the investment decision making process. In addition, government policy makers may have the opportunity for increased effectiveness in assistance programs by recognizing that the needs and preferences of founders of rapid-growth companies are significantly different from those of their slower-growing counterparts, and that these differences should be considered in the development of assistance programs.

Among-Population Variability of Fish Growth: I. Influence of the Quantity of Food Consumed

We assessed the relationship between in situ fish growth and food consumption for a series of yellow perch (Perca flavescens) populations that exhibited a 1.8 to 10-fold range in growth rates on a weight basis. Perch from 12 populations (lakes) and three year–classes (I +, II +, and III +) were sampled at 3–4 wk intervals from late May to late September 1985. On each occasion, water temperature profile and daily ration were determined. Among-lake water temperature differences were minimal (of the 12 lakes studied 10 had mean water temperatures of 19.0 ± 1 °C) and could not explain growth differences. Food consumption covered a four-fold range within each age–class and varied significantly among populations but not among age–classes. Food consumption explained a significant proportion of among-population variability in perch growth rates only for age I + fish (r2 = 0.52). We argue that other factors such as prey type, prey availability, and fish community descriptors are important determinants of among-population growth variability in the lakes we studied, and by implication, in other systems.