Comparison of growth traits between abundant and uncommon forms of a non-native vine, Dolichandra unguis-cati (Bignoniaceae) in Australia

summaryThree groups of species (21 herbaceous monocotyledons, 22 herbaceous dicotyledons and 16 woody dicotyledons), including representatives of a wide range of natural habitats and life forms in inland Britain, were grown in the seedling phase in a resource‐rich controlled environment and assessed over a 14‐day period (21 d in the case of woody species). Mean values of relative growth rate (RGR), unit leaf rate (ULR), leaf area ratio (LAR), leaf weight fraction (LWF), specific leaf area (SLA), and the root‐shoot allometric coefficient were derived.In herbaceous species, the grand mean RGR was 0.20 d−1 comparable to values previously recorded. For woody species, the mean was 0.09 d−1. An existing assumption linking high RGR to high allocation to photosynthetic biomass was upheld by comparisons made between groups. Within groups, however, no pattern of this kind could be demonstrated.When photosynthetically active radiation was increased from 125 to 250 μmol m−2 s−1, ULR was increased almost pro rata. The parallel response in RGR was only slight, being offset by considerable reductions in LAR. The apparent mean quantum yield for photosynthesis in herbaceous species (whole‐plant d. wt basis) was 0–60 g mol−1.There was no significant dependence of RGR on ULR in any of the three groups of species, although the absolute magnitude of ULR declined in the order: herbaceous monocotyledons > herbaceous dicotyledons > woody dicotyledons. In all three groups, RGR was strongly dependent upon LAR but no differences emerged in absolute scale of LAR. The absolute scale of mean LWF decreased from herbaceous to woody species, but the dependence of LAR on LWF strengthened. Groups showed no systematic differences in magnitude of SLA, but the correlation of LAR with SLA was strong throughout.Multiple regression showed that the leading determinants of RGR were ULR and SLA in herbaceous species and LWF in woody species. Principal components analyses (PCA) on each of the three groups explained at least 77% of variation and agreed closely with an optimal (non‐hierarchical) classification. Only six cluster ‘types’ were recognized out of the 16 theoretically possible combinations of ‘high’ or ‘low’ values of the four growth parameters. Strong evidence of evolutionary trade‐offs emerged, most strikingly in that high RGR was never seen in combination with low SLA. The morphological/physiological types identified by an all‐groups PCA separated woody from the herbaceous species, but dicotyledons were almost congruent with the monocotyledons.The non‐growth‐analytical attributes most strongly correlated with mean RGR were percentage yield at a low level of mineral nutrients, leaf nitrogen concentration, and seed weight. It was concluded that mean RGR plays a central role in the identification of pathways of evolutionary specialization in herbaceous species.

Growth responses of Nymphoides indica seedlings and vegetative propagules along a water depth gradient

Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Australia. This investigation aimed to evaluate and compare germination behavior and occurrence of polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from the short pod form exhibited significantly higher germination rates and higher occurrence of polyembryony than those from the long pod form. Seeds from the long pod form did not germinate at the lowest temperature of 10/20°C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate. Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed form in Australia, while the long pod form is confined to a few localities. The results have implication in predicting future ranges of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed.

The relationships between relative growth rate and its components across 11 submersed macrophytes were examined in a short-term experimental study. Plants were grown in identical conditions in pots that were submersed in tanks. The average values for relative growth rate ranged from 17.4 to 94.5 mg g−1 d−1. The net assimilation rate, based on the increase in plant dry weight per unit leaf area in a fixed time, varied fivefold among species and showed a strong, positive correlation with relative growth rate. The leaf area ratio, leaf mass ratio, and specific leaf area were not significantly correlated with the relative growth rate, although these parameters were important in the adaptive responses of macrophytes to environmental stress. These results suggest that the physiological components (net assimilation rate) would be the main determinant of relative growth rate in submersed macrophytes, which highlights the importance of net assimilation rate in explaining differences in macrophyte species performance in freshwater habitat.

Growth analysis of nine multipurpose woody legumes native from southern Mexico

The study investigated the impact of the interaction between soybean and rhizobia on the assimilation apparatus functioning and biomass accumulation in different soybean lines with varying photoperiod sensitivity. Nearly isogenic lines (NILs) of soybean were used, with genes E1, E2, and E3 in different allelic states: Clark (e1E2E3), L80-5879 (E1e2e3), L63-3117 (e1e2E3), and L71-920 (e1e2e3). The experimental group for each line was treated with Bradyrhizobium japonicum 634b. Plants were grown under natural long-day conditions (16 hours). Growth indicators of the studied lines, such as relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and specific leaf area (SLA), were analyzed, as well as the content of chlorophylls A and B in the V3 and V5 developmental stages. The results demonstrate that the influence of rhizobia on the functioning of the assimilation apparatus and biomass accumulation depends on the soybean line genotype. In the study, RGR, which characterizes the biomass accumulation rate, has similar trends to those observed with NAR, characterizing the assimilation apparatus's functioning. However, each line showed its own tendencies. For instance, in the short-day variety Clark, under bacterial influence, the value of RGR and NAR decreased. Additionally, LAR and SLA values indicated a reduction in the total photosynthetic surface area and leaf dry matter. Bacterial inoculation did not significantly affect the content of photosynthetic pigments in Clark leaves. Another short-day line, L80-5879, showed no significant impact of bacterial inoculation on biomass accumulation. However, soybean interaction with Bradyrhizobium japonicum 634b led to a decrease in leaf surface area and dry matter content. Probably, bacterial inoculation supported assimilation processes by increasing auxiliary chlorophyll b in photosystem I. A general trend of significant RGR reduction in neutral-day soybean lines, L63-3117 and L71-920, was identified under bacterial influence. The interaction with rhizobia differently affected LAR and SLA values, indicating distinct adaptive mechanisms to the interactions. In conditions of almost zero plant biomass accumulation, Bradyrhizobium japonicum 634b caused a decrease in the total photosynthetic surface area and chlorophyll a and b content in the L63-3117 line. In L71-920, bacterial inoculation had no effect on the total photosynthetic surface area, while leaf dry matter and photosynthetic pigment content decreased. The obtained results demonstrate that interaction with rhizobia can influence the functioning of the assimilation apparatus in soybeans with varying photoperiod sensitivity that is determined by genotype. It is important in improving soybean productivity and its application in agricultural practices.

This work was conducted to study the effect of five NPK fertigation levels on the growth rate of sweet pepper (Capsicum annuum L. cv. Bruyo) grown under the plastic greenhouse using different growth analysis formulas. Leaf area ratio (LAR), specific leaf area (SLA), relative growth rate (RGR) and net assimilation rate (NAR) was evaluated in two periods (60–90 and 90–120 days after transplanting). The mean values of LAR, SLA, RGR and NAR tended to decrease significantly with advancing plant age in both seasons. In general, at the moderate level (34N-42P-29K / plastic house 540 m2) was found the highest significant values of LAR and SLA in the two growth periods. On the other hand, the highest values of NAR were recorded at the plants treated with the lowest NPK fertigation level (17N-21P-15K / plastic house 540 m2). However, increase of NPK fertigation doses to the moderate levels had favorable effects on LAR and SLA of sweet pepper plants.

Tilapia (Oreochromis niloticus) is one of the leading freshwater fish commodities in Indonesia. The problem often faced by tilapia farmers is the low level of feed utilization, especially protein, which is still low, resulting in suboptimal growth. The glutamate content in monosodium glutamate (MSG) can act as a precursor for the formation of arginine and glutamine, which can increase the production of protease and lipase enzymes that are excreted into the intestines during the feed hydrolysis process, which is useful in increasing the absorption of nutrients in the form of protein and fat. This research was conducted using fingerling tilapia as a test fish with an average individual length of 6.59 ± 0.21 cm/fish and an average individual weight of 5.33 ± 0.27 g/fish. This research was carried out in an aquarium container measuring 40x30x30 cm with a water volume of 27 l and a density of 15 fish/aquarium. The aim of this research was to determine the effect of MSG in fish feed on total feed consumption (TKP), feed utilization efficiency (FUE), protein efficiency ratio (PER), protein retention, relative growth rate (RGR), and survival (SR) in fingerling tilapia. This research used an experimental method with a completely randomized design (CRD) of 4 treatments with 3 replications. Treatments A, B, C, and D are fed with the addition of 0 MSG in commercial feed; 0.75; 1.5; and 2.25 g/kg. Variables observed included TKP, FUE, PER, protein retention, RGR, and SR. The research results showed that MSG in feed had a significant effect (P < 0.05) on the FUE, PER, protein retention, and RGR values but had no effect (P < 0.05) on the TKP and SR values. FUE value; PER, protein retention; The highest RGR was obtained in treatment D (2.25 g/kg); FUE (87.21±2.28); PER(1.83±0.05); protein retention (50.47±0.76); The RGR (3.06 ± 0.03) and survival value for all treatments were found to be 100%. The water quality during the research was in optimal condition.

ABSTRACTSmall birch plants were grown for up to 80 d in a climate chamber at varied relative addition rates of nitrogen in culture solution, and at ambient (350 μmol mol‐1) or elevated (700 μmol mol‐1) concentrations of CO2. The relative addition rate of nitrogen controlled relative growth rate accurately and independently of CO2 concentration at sub‐optimum levels. During free access to nutrients, relative growth rate was higher at elevated CO2. Higher values of relative growth rate and net assimilation rate were associated with higher values of plant N‐concentration. At all N‐supply rates, elevated CO2 resulted in higher values of net assimilation rate, whereas leaf weight ratio was independent of CO2. Specific leaf area (and leaf area ratio) was less at higher CO2 and at lower rates of N‐supply. Lower values of specific leaf area were partly because of starch accumulation. Nitrogen productivity (growth rate per unit plant nitrogen) was higher at elevated CO2. At sub‐optimal N‐supply, the higher net assimilation rate at elevated CO2 was offset by a lower leaf area ratio. Carbon dioxide did not affect root/shoot ratio, but a higher fraction of plant dry weight was found in roots at lower N‐supply. In the treatment with lowest N‐supply, five times as much root length was produced per amount of plant nitrogen in comparison with optimum plants. The specific fine root length at all N‐supplies was greater at elevated CO2. These responses of the root system to lower N‐supply and elevated CO2 may have a considerable bearing on the acquisition of nutrients in depleted soils at elevated CO2. The advantage of maintaining steady‐state nutrition in small plants while investigating the effects of elevated CO2 on growth is emphasized.

Summary • Close correlations between specific leaf area (SLA) and relative growth rate (RGR) have been reported in many studies. However, theoretically, SLA by itself has small net positive effect on RGR because any increase in SLA inevitably causes a decrease in area‐based leaf nitrogen concentration (LNCa), another RGR component. It was hypothesized that, for a correlation between SLA and RGR, SLA needs to be associated with specific nitrogen absorption rate of roots (SAR), which counteracts the negative effect of SLA on LNCa.• Five trees and six herbs were grown under optimal conditions and relationships between SAR and RGR components were analyzed using a model based on balanced growth hypothesis.• SLA varied 1.9‐fold between species. Simulations predicted that, if SAR is not associated with SLA, this variation in SLA would cause a 47% decrease in LNCa along the SLA gradient, leading to a marginal net positive effect on RGR. In reality, SAR was positively related to SLA, showing a 3.9‐fold variation, which largely compensated for the negative effect of SLA on LNCa. Consequently, LNCa values were almost constant across species and a positive SLA–RGR relationship was achieved.• These results highlight the importance of leaf–root interactions in understanding interspecific differences in RGR.

Seedling relative growth rate (RGR) achieved under favourable growth conditions can be thought of as a useful bioassay of the potential ability of species to take advantage of favourable growth opportunities; that is, of a species' growth strategy. The consistency of relationships between RGR and its component attributes leaf nitrogen productivity (LNP), leaf N per area (LNCa), specific leaf area (SLA) and leaf mass ratio (LMR) was assessed across 12 datasets comprising three growth forms (grasses, herbaceous dicots and woody plants; 250 species in total). These relationships were characterised in terms of scaling slopes (regressions on log-log axes, the slopes giving the proportional relationship between the variables). Mathematically, the expected scaling slope between RGR and each component is 1.0, giving an appropriate null hypothesis to test against (whereas the widely used null hypothesis of zero correlation is in fact inappropriate for this situation). Deviations below 1:1 scaling slopes indicate negative covariance between the components. Consequently, the correlation structure between the components of RGR should also be investigated. Biologically, RGR should scale 1:1 with SLA at a given LNCa and somewhat more weakly with LNCa at a given SLA. SLA and LNCa should themselves scale with a slope of between 0 and -1, with the actual slope indicating the extent to which between-species variation in SLA dilutes leaf N on an area basis versus the ability of species to maintain LNCa at a given growth irradiance. On average, across the 12 datasets RGR scaled close-to-proportionally with SLA, and 1:1 with SLA at a given LNCa. RGR scaled with LNCa with null or negative slopes, since SLA and LNCa scaled negatively (with slopes generally shallower than -1); however, RGR scaled positively (but less than proportionally) with LNCa at a given SLA. For these key relationships there were no qualitatively different conclusions with respect to the growth form under consideration or the growth irradiance at which the seedlings were grown. RGR also scaled close-to-proportionally with LNP, while LNP and LNCa were negatively associated. These relationships involving LNP are difficult to interpret since it can be shown that they are, at least potentially, the result of the interactions between RGR, SLA and LNCa, as well as reflecting intrinsic differences in the efficiency of nitrogen use in the growth process.

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

O objetivo deste trabalho foi analisar o crescimento de três cultivares de Panicum maximum: Mombaça, Tanzânia e Vencedor cultivados em vasos, sob cobertura de lona plástica transparente. Os vasos foram cheios com 6 dm³ de latossolo vermelho-amarelo, textura argilosa, contendo alto teor de matéria orgânica. O solo, após ser peneirado, recebeu calagem e enriquecimento com N e P, 150 mg/dm³ de cada elemento. As sementes foram plantadas em vasos, num total de 54. Após desbaste, cinco plantas foram deixadas por vaso. Diariamente os vasos foram molhados e quinzenalmente fertilizados, cada um, com 50 mg/dm³ de N e K, em solução aquosa. Cada cultivar foi colhido às idades de 17, 24, 31, 38, 45 e 52 dias após emergência da semente. Houve três repetições para cada cultivar e idade. Em cada colheita, as plantas foram cortadas próximo à superfície do solo e separadas em folhas, colmo, raízes e material morto. A área das lâminas foliares foi medida em integrador de área foliar. Lâminas foliares, colmo e sistema radicular foram pesados após secagem a 60ºC por 72 horas. Valores instantâneos foram estimados para os índices de crescimento: área foliar específica (AFE), razão de peso foliar (RPF), razão de área foliar (RAF), taxa assimilatória líquida (TAL) e taxa de crescimento relativo (TCR), de todos três cultivares. Houve diferenças entre os cultivares quanto aos valores instantâneos de RAF e TCR à idade de 17 dias. As variações de AFE foram as principais causas das mudanças em RAF. Nenhuma diferença foi observada entre os cultivares quanto à TAL.

Crossovers in seedling relative growth rates between low and high irradiance: analyses and ecological potential

Forests and shrublands occupy a large area in the world (c. 31% of the total continental area) and in Spain (c. 36% of the area), in which around 30% of forests are formed by Quercus species. Therefore, the ecosystem services provided by Quercus species are critical to human well-being. Thus, it is essential to understand how Quercus species grow and how they will respond to global change. Bringing together data of comparative growth experiments with seedlings, field data and allometric equations developed for adult plants, our main objectives for this chapter are: (1) to quantify the relative growth rates (RGR) and growth components of seedlings of Quercus species and compare them to values of woody species belonging to other families; (2) to characterise biomass allocation patterns in leaves, stem and roots and RGR in Quercus adults; (3) to understand how temperature, precipitation, tree size and tree density affect the RGR of adult Quercus species; and (4) to compare the RGR of seedlings and adults, and identify which functional traits can explain the differences in RGR. Compared to woody species from other families, seedlings of Quercus species were characterized by low RGR and specific leaf area (SLA), a high proportion of biomass invested in roots (RMF, root mass fraction) and a large seed mass. One of the most important traits explaining differences in RGR among seedlings of Quercus species was the leaf area ratio (LAR, total leaf area per unit of total biomass). In Quercus species, the fraction of biomass in leaves (LMF) and roots (RMF) decreased with tree size, while the proportion of biomass in stems (SMF) increased. Thus, for a tree with 20 cm diameter at breast height, the values of LMF were only between 0.01 and 0.05 (i.e. 1–5% of total biomass invested in leaves) and SMF ranged from 0.50 to 0.80. RGR values of adult Quercus species were highly variable, due to differences in tree size, stand density and abiotic factors. Tree size and density negatively affected RGR, so bigger trees tend to grow more slowly. However, the variation in RGR explained by temperature and/or precipitation was relatively low (<7% of total variation).We observed a positive relationship between the RGR of seedlings in controlled conditions and those of adults in the field. Furthermore, median RGR values of adult plants for Quercus species were positively related to SLA and leaf nitrogen. To sum up, Quercus species differ in RGR and key leaf traits from other woody species and the RGR of adult trees depend on tree size, density, temperature and precipitation. Our results suggest that climate change synchronised with density might affect future trends on the growth of Quercus species.