Initial Relative Growth Rate Research Articles

Growth and form of giant sequoia (Sequoiadendron giganteum) in a plantation spacing trial after 28 years

Giant sequoia is a famously massive and long-lived tree endemic to the Sierra Nevada of California, whose persistence is threatened by a changing climate and an altered disturbance regime. One approach for protecting threatened species is to incorporate them into working landscapes. In a forestry context, the objectives of a working landscape include the production of timber and the storage of carbon. Given its potential for rapid growth, an understanding of the growth-density relationships for giant sequoia is a necessity for planning future management for these common management objectives. To investigate the effect of initial planting density on both individual tree and stand level characteristics, we used repeated measures data from a 28-year-old giant sequoia spacing trial. After 28 years, survival among all spacing treatments was high (>98%). Individual bole volume increased with greater growing space allocated per tree. Although initial relative growth rates based on bole volume differed among spacing treatments, relative growth rates were similar after 21 years. At the stand level, total stand volume was similar across all spacing treatments after 28 years. However, wider spacing treatments exhibited higher amounts of merchantable volume. After 28 years, stands of giant sequoia sequestered approximately 92.2 Mg ha−1 across all spacing treatments. Our results show that giant sequoias are able to produce merchantable timber at a young age and sequester large amounts of carbon in a relatively short amount of time, supporting that giant sequoia is a promising candidate species for planting for timber production as well as carbon sequestration.

Organic Fertilizers and Biofertilizers to Improve Growth, Yield and Nutrient Quality of Soybean (Glycine max L.)

Soybean (Glycine max L.) is one of the major legume crops cultivated in the dryzone of Sri Lanka. Most farmers use excess amounts of synthetic fertilizer to increase the yield of soybean and this causes serious health and environmental problems. Organic and biofertilizers can be used as an alternative, is a reliable solution for avoid the many of problems of synthetic fertilizer. The microbial consortium in the soil is critical to improve soil quality in agricultural fields. Organic residue recycling is becoming an increasingly important aspect of environmentally sound sustainable agriculture. Interactions of organic fertilizers with soil microorganisms are complex and improve the growth and yield of crops in tropical soil. The present study was conducted to find the effectiveness of organic and biofertilizers as an alternative to chemical fertilizer on growth yield and nutritional quality of soybean. A pot experiment was carried out in plant house at Faculty of Applied Sciences Mihintale, dryzone of Sri Lanka. Treatments were field soil only (T0), field soil and 5% biochar (T1), field soil and 5% cow dung (T2), field soil, 2.5% biochar and 2.5% cow dung (T3), field soil, 5% biochar and Bradyrhizobium (T4), field soil, 5% biochar and mycorrhizae (T5), field soil, 5% cow dung and Bradyrhizobium (T6) field soil, 5% cow dung and mycorrhizae (T7), field soil and synthetic fertilizer (T8), field soil, 2.5% cow dung 2.5% biochar and synthetic fertilizer (T9), field soil, 5% cow dung, mycorrhizae and Bradyrhizobium (T10), field soil, 5% biochar, mycorrhizae and Bradyrhizobium (T11). The treatments were tested in a Completely Randomized Block Design (CRBD) with six replicates. Considering the growth, significantly high (p<0.05) initial relative growth rate, number of leaflets, root dry weight, shoot dry weight, nodule dry weight was observed in T9, the addition of 2.5% cow dung, 2.5% biochar and synthetic fertilizer. Soybean yield such as number of pods and dry weight of 100 seeds were significantly high (p<0.05) in T10, the addition of field soil, 5% cow dung, mycorrhizae and Bradyrhizobium. Higher seed protein percentage was observed in T10, fat percentage in T4 and crude fiber percentage in T8 treatments. It can be concluded that yield and nutrient quality of soybean can be enhanced by the application of organic and biofertilizers together. This provides optimism for applying organic and biofertilizers on sustainable agricultural practices in dryzone of Sri Lanka. Keywords: Biofertilizers, Organic fertilizers, Glycine max, Growth, Yield, Nutrient quality

QualiTree, a virtual fruit tree to study the management of fruit quality. II. Parameterisation for peach, analysis of growth-related processes and agronomic scenarios

In this paper, QualiTree, a fruit tree model designed to study the management of fruit quality, and developed and described in a companion paper (Lescourret et al. in Trees Struct Funct, 2010), was combined with a simple light-interception sub-model, and then parameterised and tested on peach in different situations. Simulation outputs displayed fairly good agreement with the observed data concerning mean fruit and vegetative growth. The variability over time of fruit and vegetative growth was well predicted. QualiTree was able to reproduce the observed response of trees to heterogeneous thinning treatments in terms of fruit growth. A sensitivity analysis showed that the average seasonal growth rates of the different organs were sensitive to changes to the values of their respective initial relative growth rates and that stem wood was the tree organ the most affected by a change in the initial relative growth rates of other organs. QualiTree was able to react to simulated scenarios that combined thinning and pest attacks. As expected, thinning intensity and the percentage damage caused by pests significantly affected fruit yield and quality traits at harvest. These simulations showed that QualiTree could be a useful tool to design innovative horticultural practices.

Effects of Cattle Slurry on the Growth Potential and Clover Proportion of Organically Managed Grass-Clover Leys

The growth potential of grass-clover leys as influenced by cattle slurry application and clover content was studied in field experiments during three growing seasons at four locations. A grassland growth model was used to quantify growth potential and to separate the influence of weather variables from factors related to the plant stand. Application of cattle slurry increased the initial relative growth rate ( R s ), on average from 0.21 to 0.23 g g -1 day -1 of the spring growth. In regrowth the effect of cattle slurry was less pronounced. The effect of cattle slurry declined with increasing R s of the unfertilized treatment and rose with increasing rate of ammonium N applied by the slurry. The positive response to cattle slurry application on R s was unaffected by the clover proportion in the spring growth, while in regrowth it tended to diminish with increasing clover proportion. A rising clover proportion enhanced the growth potential of the ley in both growth periods. In spring growth, highest R s was found at an average clover content of approximately 55%, while in regrowth R increased linearly with the clover content. On average, slurry application reduced the clover proportion of dry matter yield by 7%-units in spring growth and 13%-units in regrowth.

Improved growth and water use efficiency of cherry saplings under reduced light intensity

Cherry (Prunus avium L.) saplings were grown under natural sunlight (controls) or moderate shading (up to 30%, depending on the incident light intensity and the hour of the day). Reduced light intensity increased the dry mass of each of the plant components studied. Consequently, the total dry mass of shaded plants was significantly greater than that of controls at the end of the growing season. However, the diurnal trend in the level of photosynthesis (per unit of leaf area) of shaded plants was similar to the controls in August, but lower in September. As the growing season proceeded, reduced photosynthetic rates, thinner mesophyll and larger specific leaf area in the shaded plants indicated that leaf development had adapted to shaded conditions throughout the growing season. It is suggested that increased growth of shaded plants was caused by a higher initial relative growth rate and a greater whole‐plant photosynthesis. Shading consistently reduced transpiration over the season, therefore improving water use efficiency of shaded leaves. Our results suggest that a moderate reduction in light intensity can be a useful method for improving growth and saving water in hot and dry environments.

Modelling Asymmetrical Growth Curves that Rise and then Fall: Applications to Foliage Dynamics of Sugar Beet (Beta vulgarisL.)

Abstract This paper discusses the derivation and fitting of three empirical models with turning points for describing the growth of plant components, such as shoot weight, leaf area and root length, that typically rise and then fall during the course of the growing season. The models (Models I, II and III) have analytical solutions and may be viewed as extensions of the Gompertz, Richards and Chanter growth equations. They differ by having an additional parameter which, following a sigmoidal rise of the dependent variable, determines subsequent net rate of decline. The models were fitted to sequential measures of foliage cover of sugar beet crops grown in the UK during 1980–1991. It was important that this could be done with relative ease using standard statistical procedures. Partial linear transformations of two of the models, with one non-linear parameter remaining, are described; these were useful for estimating initial values for the parameters. All three models described the data well, although the fitting of Model II invariably failed to converge. For Models I and III common and separate parameters, amongst years, were estimated relating to date of emergence, initial relative growth rate, maximum cover attained and rate of late season decline of foliage cover. The reduction in the residual mean square on fitting separate, rather than common, parameters was usually significant. The models accommodate several biological processes that yield similar shapes. This is demonstrated for Model I, in relation to its formulation and to effects of small perturbations in the values of the parameters on the shape of the curves. Model I, the simplest of the three models tested, has good fitting properties, and in practice was best suited to describing foliage cover dynamics of sugar beet.

The impact of elevated CO2 on growth and photosynthesis in Agrostis canina L. ssp. monteluccii adapted to contrasting atmospheric CO2 concentrations.

The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric CO2 concentrations (C a). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2 transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2 (350 and 700 μmol mol-1) in nutrient-rich soil. Seasonal mean C a at the source of the plant material ranged from 610 to 451 μmol CO2 mol-1, derived from C4 leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2 enrichment stimulated the growth of all populations. However, plants originating from elevated C a exhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2 concentrations and a positive relationship was found between RGR and C a at the seed source. Seed weight was positively correlated with C a, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol CO2 mol-1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol CO2 mol-1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high C a exhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2 saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2 treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no difference in Rubisco content between populations or CO2 treatments. These findings suggest that long-term adaptation to growth at elevated CO2 may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic capacity for photosynthesis.

Maternal Phenotypic Effects Due to Soil Nutrient Levels and Sink Removal in Arabidopsis thaliana (Brassicaceae)

Three levels of soil nutrients and systematic removal of racemes and siliques, intended to reduce reproductive sink size, induced maternal effects in a genetically uniform, inbred accession of Arabidopsis thaliana ecotype Col-0. Soil nutrient levels but not trimming treatments caused significant differences in maternal plant weight and number of seeds per silique. Trimming and increased soil nutrient level resulted in larger seeds. Germination rates were significantly affected only by the trimming main effect, while there were no significant effects on germination percentage. At 14 and 19 d harvest dates, soil nutrient level treatments resulted in significant differences in offspring aerial biomass, but this effect was nonsignificant at 24, 29, and 34 d harvest dates. The effect of trimming on offspring aerial biomass was significant at all harvest dates. No significant soil nutrient level × trimming interaction was observed on any harvest date. Phenotypic correlations among aerial biomass at each harvest date and seed weight of the six offspring classes were highly significant. Analyses of variance for germination and biomass data adjusted for seed weight showed no significant differences due to soil nutrient level, trimming, or their interaction, indicating that maternal effects influencing these variables were determined by seed weight. Relative growth rates were estimated from changes in biomass over time. The negative correlation between initial relative growth rate and rate of change of the relative growth rate was highly significant (R = -0.99; P < 0.01).

Maternal phenotypic effects due to soil nutrient levels and sink removal in Arabidopsis thaliana (Brassicaceae)

Three levels of soil nutrients and systematic removal of racemes and siliques, intended to reduce reproductive sink size, induced maternal effects in a genetically uniform, inbred accession of Arabidopsis thaliana ecotype Col‐0. Soil nutrient levels but not trimming treatments caused significant differences in maternal plant weight and number of seeds per silique. Trimming and increased soil nutrient level resulted in larger seeds. Germination rates were significantly affected only by the trimming main effect, while there were no significant effects on germination percentage. At 14 and 19 d harvest dates, soil nutrient level treatments resulted in significant differences in offspring aerial biomass, but this effect was nonsignificant at 24, 29, and 34 d harvest dates. The effect of trimming on offspring aerial biomass was significant at all harvest dates. No significant soil nutrient level × trimming interaction was observed on any harvest date. Phenotypic correlations among aerial biomass at each harvest date and seed weight of the six offspring classes were highly significant. Analyses of variance for germination and biomass data adjusted for seed weight showed no significant differences due to soil nutrient level, trimming, or their interaction, indicating that maternal effects influencing these variables were determined by seed weight. Relative growth rates were estimated from changes in biomass over time. The negative correlation between initial relative growth rate and rate of change of the relative growth rate was highly significant (R = ‐0.99; P &lt; 0.01).

Divergent Selection for Growth in Japanese Quail Under Split and Complete Nutritional Environments.: 6. Differential Body Weights in Reciprocal Crosses

Growth patterns were investigated in reciprocal crosses of quail lines divergently selected for 4-wk BW. In Experiment 1, quail from two sets of high lines (H), and two sets of low lines (L), and their reciprocal crosses (HL and LH) from Generation 23 breeders were reared intermingled and fed a 28% CP diet. Individual BW data were collected weekly through 9 wk. Experiment 2 involved only reciprocal cross progeny (HL, LH) from Generation 26 breeders with quail placed in divided decks of battery brooders to allow collection of feed intake and feed efficiency (FE) data. Feed intake data were collected from 0 to 38 days and BW data from 0 to 69 days. Quail from the LH cross were significant1ly (P < .05) larger than quail from the HL cross from 0 to 14 days and 0 to 69 days in Experiments 1 and 2, respectively. Initial BW differences were expected because of the large egg size difference between H and L line dams; however, persistent BW differences were not anticipated. Initial feed intake was greater (25%) for LH than HL quail; however, when adjusted for BW, HL quail consistently consumed more feed per gram of BW than LH quail. Feed efficiencies were not significantly different for the two genotypes; however, smaller HL quail tended to have superior FE after 2 wk of age. Initial relative growth rates were 17 to 38% higher in HL quail; however, after Week 2 absolute gain was essentially identical for the reciprocal crosses.

A Comparative Study of the Growth and Morphology of Eight Grass Species from Habitats with Different Nutrient Availabilities

1. To find out which properties enable plant species to dominate in nutrient-poor habitats and which properties benefit species in nutrient-rich habitats, we studied the growth and morphology of eight perennial grass species from habitats with contrasting soil fertilities in a pot experiment under controlled conditions in a glasshouse. 2. The species were grown under nutrient-poor and nutrient-rich conditions. Ranked from the least responsive to the most responsive to the supply of nutrients they were: Festuca ovina, F. rubra, Anthoxanthum odoratum, F. arundinacea, Alopecurus pratensis, F. pratensis, Arrhenatherum elatius, Lolium perenne. 3. The response correlated positively with the Ellenberg nitrogen number of the species. No differences in initial relative growth rate were found between the species, but after 4 weeks the plant dry weight increased with increasing nitrogen number as a result of variation in embryo plus endosperm weight. 4. Species characteristic of nutrient-rich hayfields are taller and show a more homogeneous vertical distribution of photosynthetic area than the species from nutrient-poor habitats, which have most of their leaf area below 15 cm. Species from the nutrient-poor habitats allocated less dry matter to the roots and consequently more to the shoot, than species from nutrient-rich conditions. However, leaf and root morphology seem to be most clearly adapted to the habitat. 5. Species from nutrient-rich habitats have a higher specific leaf area (SLA) than species from nutrient-poor habitats, while species from nutrient-poor habitats had more root length per unit root weight (SRL) than species from nutrient-rich habitats.

Seed Size Variation and Its Effects on Seedling Growth in Agropyron psammophilum

Seed size variation and its effects on germination and seedling growth were examined in seeds collected from a population of Agropyron psammophilum on a sand dune system along Lake Erie. Seed size varied from 0.8 to 5.1 mg per seed. Total germination of seeds was not affected by seed size, but large seeds germinated significantly faster than did small seeds. The leaf area and absolute dry weight of 10-20-d-old seedlings from large seeds were significantly higher than those from small seeds. These differences disappeared in seedlings harvested 30 and 40 d after emergence owing to a higher initial relative growth rate in seedlings from small seeds but reappeared in seedlings harvested 50 and 60 d after emergence. The relative growth rate of seedlings from both small and large seeds decreased with time. However, the rate of decrease was greater in seedlings from small seeds, which eventually resulted in seedlings of smaller size than those from large seeds at later stages of development.

Comparative responses of the Savanna grasses Cenchrus ciliaris and Themeda triandra to defoliation.

Two perennial tussock grasses of savannas were compared in a glasshouse study to determine why they differed in their ability to withstand frequent, heavy grazing; Cenchrus ciliaris is tolerant and Themeda triandra is intolerant of heavy grazing. Frequent defoliation at weekly intervals for six weeks reduced shoot biomass production over a subsequent 42 day regrowth period compared with previously undefoliated plants (infrequent) in T. triandra, but not in C. ciliaris. Leaf area of T. triandra expanded rapidly following defoliation but high initial relative growth rates of shoots were not sustained after 14 days of regrowth because of reducing light utilising efficiency of leaves. Frequently defoliated plants were slower in rate of leaf area expansion and this was associated with reduced photosynthetic capacity of newly formed leaves, lower allocation of photosynthate to leaves but not lower tiller numbers. T. triandra appears well adapted to a regime where defoliation is sufficiently infrequent to allow carbon to be fixed to replace that used in initial leaf area expansion. In contrast, C. ciliaris is better adapted to frequent defoliation than is T. triandra, because horizontally orientated nodal tillers are produced below the defoliation level. This morphological adaptation resulted in a 10-fold higher leaf area remaining after defoliation compared with similarly defoliated T. triandra, which together with the maintenance of moderate levels of light utilising efficiency, contributed to the higher leaf area and shoot weight throughout the regrowth period.

Report on discussion of paper by P. J. H. Sharpe.

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The growth of the young coconut palm (Cocos nucifera L.). I. The role of the seed and of photosynthesis in seedling growth up to 17 months of age

The growth of coconut seedlings and the changes occurring within the seed were studied over a period of 17 months from the germination of the coconuts. Removal of the husk prior to germination made possible an estimate of the endosperm content of each seed and also permitted the exact date of germination to be observed. Seedlings were grown with a non-limiting supply of water and nutrients; 63 seedlings were harvested on each of 10 occasions to enable a growth analysis to be made. A high initial relative growth rate, arising through contributions by the endosperm, fell at 4 months to a level which remained roughly constant to 17 months. By 4 months the haustorium had reached its full size, but thereafter the relative contribution from the endosperm via the haustorium was much diminished. Between 4 and 15 months a gradual change over to full dependence on photosynthesis took place. By 17 months less than 10% of the endosperm remained in the nut. The rate of leaf production was constant with time, but the leaf area increased almost exponentially. There was some indication of a positive relationship between net assimilation rate and solar radiation. Some conclusions are drawn concerning cultural methods with young coconuts.