Leaf Growth Traits Research Articles

Why Are Widely Distributed Species Widely Distributed? Understanding From a Quantified Investment Acquisition Strategy.

Research on plant functional traits have advanced our understanding of plant investment acquisition strategies. However, it is still unknown how a plant investment acquisition strategy varies or how the relative position of plants on the leaf economic spectrum changes across different habitats. Therefore, we conducted the field experiments at two long-term ecological research sites in Shandong and Xinjiang, China, in August 2023. Twenty-two common species in both sites and four endemics in each site were selected for leaf gas exchange traits, leaf growth traits, and leaf nutrient trait measurements. We used two different methods to quantify the leaf economic spectrum, PCA quantification and functional area quantification. We found that the 22 common species had a significantly faster investment acquisition strategy than local endemics on the leaf economic spectrum. Besides, the plasticity of the 22 common species was not coupled with the plasticity of their investment acquisition strategy. According to our results, we quantified and constructed the leaf economic spectrum of the 30 woody plant species in Shandong and Xinjiang and discussed that high plasticity and fast investment acquisition strategy may be an ecological adaptation and distribution strategy for widely distributed species.

The Effect of Inoculation of Growth-Stimulating Bacteria on Some Leaf Growth Traits and Nutritional Elements of Hazelnut Seedlings Under Field Conditions

The Effect of Inoculation of Growth-Stimulating Bacteria on Some Leaf Growth Traits and Nutritional Elements of Hazelnut Seedlings Under Field Conditions

Whole-plant compensatory responses of isoprene emission from hybrid poplar seedlings exposed to elevated ozone

It is still unclear whether the responses of isoprene (ISO) emission to elevated O3 vary with biological organization level (i.e. leaf and whole-plant). To study such responses and the possible reasons explaining their variation, we investigated the effect of O3 (CF: charcoal-filtered ambient air; E-O3: non-filtered ambient air enriched with O3) on ISO emission rate (ISOrate), net photosynthetic rate (Pn), leaf nitrogen and carbon contents, and leaf growth traits in poplar seedlings (Populus deltoides cv. 55/56 × P. deltoides cv. Imperial) during one growing season. Opposite effects of E-O3 on Pn were found between upper leaves (positive effect) and lower leaves (negative effect). Compared to CF, E-O3 significantly decreased leaf mass per area, number of leaves, and leaf biomass, but increased leaf nitrogen content and individual leaf size. In the framework of such compensatory responses, poplar seedlings further increased ISOrate in upper leaves and decreased ISOrate in lower leaves, thus preventing significant decrease in the overall whole-plant ISOrate by E-O3. The measured whole-plant ISOrate also showed that the simplistic estimation approaches based on the linear regression between chlorophyll content indicated by soil plant analysis development meter (SPAD value) and leaf-level ISOrate could not accurately reflect the true response of whole plant to elevated O3. For more accurate predictions, the potential ISO compensatory response to increasing O3 concentration should be incorporated into the climate biogeochemical models related to ISO emission.

Leaf growth traits and photosynthetic pigments of maize as influenced by water deficit stress

Glasshouse study was carried out to evaluate the impacts of water deficit stress (WDS) on leaf growth and photosynthetic pigments of four maize varieties at the Institute of Agricultural Research and Training, Ibadan. Seeds from ‘TZPBSR-W’, ‘ILE1OB’, ‘ART98SW6OB’ and ‘DTESYNSTR’ maize varieties were sown in sixty-four pots in a 4 x 4 factorial CR Design(r=4). The WDS treatments include 100%, 75%, 50% and 25% field capacities (FC). Data were taken weekly on specific leaf weight (SLW), leaf area (LA), leaf weight (LWT) and crop growth rate. At four weeks of WDS, extracts were obtained from 0.2 g cut leaf sample using 96% (v/v) ethanol. Light absorbance of the ethanolic leaf extract (cholorophyll-a (665 nm), chlorophyll-b (649 nm), total chlorophyll and the carotenoids (440 nm)) were read using spectrophotometer. From the results, WDS significantly reduced SLW, LWT, LA and CGR (p<0.001). The SLW ranged from 0.027±0.0 (g cm-2) (‘ART98SW6OB’) to 0.034±0.0 (g cm-2) (‘DTESYNSTR’), while the LA ranged from 269.7±25.4 (cm2) (‘ART98SW6OB’) to 220.9±20.9 (cm2) (‘ILE1OB’). Water deficit stress significantly reduced chlorophyll-b (p<0.01), chlorophyll-a and total chlorophyll (p<0.001) and the carotenoid (p<0.05). Chlorophyll-a ranged from 0.038±0.0 mg/g (‘DTESYNSTR’) to 0.050±0.0 mg/g (‘TZPBSR-W’), chlorophyll-b ranged from 0.021 mg/g (‘ART98SW6OB’) to 0.040 mg/g (‘TZPBSR-W’), total chlorophyll ranged from 0.063±0.0 mg/g (‘ART98SW6OB’) to 0.093±0.0 mg/g (‘TZPBSR-W’), while the carotenoid ranged from 0.084±0.08 mg/g (‘ART98SW6OB’) to 0.115±0.09 mg/g (‘TZPBSR-W’). The WDS and Variety interaction on photosynthetic pigments were significant (p<0.05). The Leaf growth traits, photosynthetic pigments and over all crop growth in maize are impaired when subjected to water deficit stress.

Flavonoid Compounds and Photosynthesis in Passiflora Plant Leaves under Varying Light Intensities.

Functional constituents in the leaves of Passiflora plants contain antidepressant and antianxiety effects which are beneficial to human health and fitness. The objective of this study was to investigate leaf growth, physiological parameters, and secondary metabolite contents of Tainung No. 1 variety (P. edulis × P. edulis f. flavicarpa.) and P. suberosa in response to three light intensity conditions, including 100% light intensity (LI-100), 50% light intensity (LI-50), and 15% light intensity (LI-15) for 2 months. The leaf number, length, width, area, dry weight (DW), minimal fluorescence (Fo), maximal fluorescence (Fm), maximum photochemical efficiency of photosystem II, and soil-plant analysis development (SPAD) values of all tested plants increased with a decreasing light intensity, except for the leaf number and DW of P. suberosa plants. Low values of the net photosynthetic rate, transpiration rate, and stomatal conductance of Tainung No. 1 leaves in the LI-15 treatment showed the acclimation capacity of these plants. These observations together with high values of leaf growth traits of Fo, Fm, SPAD, and the intercellular-to-atmospheric CO2 concentration ratio indicate their physiological plasticity, which is of fundamental importance when cultivating plants in environments with different light availabilities. Wide variations occurred in total phenol (TP), total flavonoid (TF), orientin (OR), and isovitexin (IV) contents of the two Passiflora varieties, and P. suberosa contained higher TP and TF contents than did Tainung No. 1 in each light treatment but IV content of P. suberosa was lower than that of Tainung No. 1 in the LI-15 treatment. Moreover, increases in TF, OR, and IV contents of Tainung No. 1 and P. suberosa were clear in the LI-50 and LI-100 treatments, respectively, compared to LI-15 treatment. Leaf growth, physiological parameters, and secondary metabolite accumulations in Passiflora species can be optimized for commercial production via lighting control technologies, and this approach may also be applicable to leafy vegetables to produce a stable industrial supply of high leaf yields and metabolite contents.

Leaf trait dissimilarities between Dutch elm hybrids with a contrasting tolerance to Dutch elm disease.

Previous studies have shown that Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), is able to colonize remote areas in infected plants of Ulmus such as the leaf midrib and secondary veins. The objective of this study was to compare the performances in leaf traits between two Dutch elm hybrids 'Groeneveld' and 'Dodoens' which possess a contrasting tolerance to DED. Trait linkages were also tested with leaf mass per area (LMA) and with the reduced Young's modulus of elasticity (MOE) as a result of structural, developmental or functional linkages. Measurements and comparisons were made of leaf growth traits, primary xylem density components, gas exchange variables and chlorophyll a fluorescence yields between mature plants of 'Groeneveld' and 'Dodoens' grown under field conditions. A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to reveal nanomechanical properties of the cell walls of tracheary elements such as MOE, adhesion and dissipation. 'Dodoens' had significantly higher values for LMA, leaf tissue thickness variables, tracheary element lumen area (A), relative hydraulic conductivity (RC), gas exchange variables and chlorophyll a fluorescence yields. 'Groeneveld' had stiffer cell walls of tracheary elements, and higher values for water-use efficiency and leaf water potential. Leaves with a large carbon and nutrient investment in LMA tended to have a greater leaf thickness and a higher net photosynthetic rate, but LMA was independent of RC. Significant linkages were also found between the MOE and some vascular traits such as RC, A and the number of tracheary elements per unit area. Strong dissimilarities in leaf trait performances were observed between the examined Dutch elm hybrids. Both hybrids were clearly separated from each other in the multivariate leaf trait space. Leaf growth, vascular and gas exchange traits in the infected plants of 'Dodoens' were unaffected by the DED fungus. 'Dodoens' proved to be a valuable elm germplasm for further breeding strategies.

Leaf traits in parental and hybrid species of Sorbus (Rosaceae)

Knowledge of functional leaf traits can provide important insights into the processes structuring plant communities. In the genus Sorbus, the generation of taxonomic novelty through reticulate evolution that gives rise to new microspecies is believed to be driven primarily by a series of interspecific hybridizations among closely related taxa. We tested hypotheses for dispersion of intermediacy across the leaf traits in Sorbus hybrids and for trait linkages with leaf area and specific leaf area. Here, we measured and compared the whole complex of growth, vascular, and ecophysiological leaf traits among parental (Sorbus aria, Sorbus aucuparia, Sorbus chamaemespilus) and natural hybrid (Sorbus montisalpae, Sorbus zuzanae) species growing under field conditions. A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to characterize the topography of cell wall surfaces of tracheary elements and to map the reduced Young's modulus of elasticity. Intermediacy was associated predominantly with leaf growth traits, whereas vascular and ecophysiological traits were mainly parental-like and transgressive phenotypes. Larger-leaf species tended to have lower modulus of elasticity values for midrib tracheary element cell walls. Leaves with a biomass investment related to a higher specific leaf area had a lower density. Leaf area- and length-normalized theoretical hydraulic conductivity was related to leaf thickness. For the whole complex of examined leaf traits, hybrid microspecies were mosaics of parental-like, intermediate, and transgressive phenotypes. The high proportion of transgressive character expressions found in Sorbus hybrids implies that generation of extreme traits through transgressive segregation played a key role in the speciation process.

Diversity of leaf traits related to productivity in 31 Populus deltoides x Populus nigra clones

To test if some leaf parameters are predictors of productivity in a range of Populus deltoides (Bartr.) Marsh. x P. nigra L. clones, we assessed leaf traits and productivity in 2-month-old rooted cuttings from 31 clones growing in 4-l pots in a greenhouse, under conditions of controlled temperature and optimal irrigation. We evaluated four groups of variables describing (1) productivity (total biomass), (2) leaf growth (total leaf number increment and total leaf area increment rate), (3) leaf structure (specific leaf area and nitrogen and carbon contents) and (4) carbon isotope discrimination (delta), which is negatively correlated with time-integrated water-use efficiency. High-yielding clones did not necessarily display high leaf growth rates, but they displayed a larger total leaf area, lower specific leaf area and lower leaf nitrogen concentration than clones with low productivity. Total leaf area was mainly controlled by maximal individual leaf area and total leaf area increment rate (r = 0.51 and 0.56, respectively). Carbon isotope discrimination did not correlate with total biomass, but it was associated with total number of leaves and total leaf area increment rate (r = 0.39 and 0.45, respectively). Therefore, leaf area and specific leaf area were better indicators of productivity than leaf growth traits. The observed independence of delta from biomass production provides opportunities for selecting poplar clones combining high productivity and high water-use efficiency.

Components of leaf elongation rate and their relationship to specific leaf area in contrasting grasses

Summary In grasses the leaf growth zone is the main site of shoot growth where anatomical and chemical characteristics of leaves originate. Yet, there is insufficient information to generalize as to whether the leaf growth zone reflects habitat characteristics, whether leaf growth traits are regularly interrelated, and whether they coincide with characteristics of mature leaves. Here the contribution of both length of the leaf growth zone (region where cell division and expansion occurs) and relative elemental growth rate to the variability in leaf elongation rate (LER) were examined in eight grass species from habitats with different soil fertility. Further, we examined the relationship of the above traits with specific leaf area (SLA) and its components. Growth zone length differed significantly among species (P < 0.05) and it was the trait contributing the most to LER. Using LER and derived components it was possible to classify seven out of eight species into two groups related to soil fertility. Leaf elongation rate exhibited a positive correlation to SLA and a negative correlation to leaf dry matter content. A significant relationship existed between size of the growth zone and leaf dry matter content. The results suggest that the leaf growth zone is a critically important leaf trait that explains inherent differences in LER and other plant characteristics of grass species.