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Background and Aims Leaf area (A) is a crucial indicator of the photosynthetic capacity of plants. The Montgomery equation (ME), which hypothesizes that A is proportional to the product of leaf length (L) and width (W), is a valid tool for non-destructively measuring A for many broadleaved plants. At present, the methods used to compute L and W for the ME can be broadly divided into two kinds: using computer recognition and measuring manually. However, the potential difference in the prediction accuracy using either method has not been thoroughly examined in previous studies. Methods In the present study, we measured 540 Alangium chinense leaves, 489 Liquidambar formosana leaves and 215 Liriodendron  ×  sinoamericanum leaves, utilizing computer recognition and manual measurement methods to determine L and W. The ME was used to fit the data determined by the two methods, and the goodness of fits were compared. The prediction errors of A were analysed by examining the correlations with two leaf symmetry indices (areal ratio of the left side to the right side, and standardized index for bilateral asymmetry), as well as the leaf shape complexity index (the leaf dissection index). Key Results The results indicate that there is a neglectable difference in the estimation of A between the two methods. This further validates that the ME is an effective method for estimating A in broadleaved tree species, including those with lobes. Additionally, leaf shape complexity significantly influenced the estimation of A. Conclusions These results show that the use of computer recognition and manual measurement in the field are both effective and feasible, although the influence of leaf shape complexity should be considered when applying the ME to estimate A in the future. [ABSTRACT FROM AUTHOR]

Canopy architecture in cereals plays an important role in determining yield. Leaf width represents one key aspect of this canopy architecture. However, our understanding of leaf width control in cereals remains incomplete. Classical mutagenesis studies in barely identified multiple morphological mutants, including those with differing leaf widths. Of these, we characterized the broad leaf13 (blf13) mutant in detail. Mutant plants form wider leaves due to increased post-initiation growth and cell proliferation. The mutant phenotype perfectly co-segregated with a missense mutation in the HvHNT1 gene which affected a highly conserved region of the encoded protein, orthologous to the rice NARROW LEAF1 (NAL1) protein. Causality of this mutation for the blf13 phenotype is further supported by correlative transcriptomic analyses and protein–protein interaction studies showing that the mutant HvNHT1 protein interacts more strongly with a known interactor than wild-type HvHNT1. The mutant HvHNT1 protein also showed stronger homodimerization compared with wild-type HvHNT1, and homology modelling suggested an additional interaction site between HvHNT1 monomers due to the blf13 mutation. Thus, the blf13 mutation parallels known gain-of-function NAL1 alleles in rice that increase leaf width and grain yield, suggesting that the blf13 mutation may have a similar agronomic potential in barley. [ABSTRACT FROM AUTHOR]

Background and Aims Leaf size has considerable ecological relevance, making it desirable to obtain leaf size estimations for as many species worldwide as possible. Current global databases, such as TRY, contain leaf size data for ~30 000 species, which is only ~8% of known species worldwide. Yet, taxonomic descriptions exist for the large majority of the remainder. Here we propose a simple method to exploit information on leaf length, width and shape from species descriptions to robustly estimate leaf areas, thus closing this considerable knowledge gap for this important plant functional trait. Methods Using a global dataset of all major leaf shapes measured on 3125 leaves from 780 taxa, we quantified scaling functions that estimate leaf size as a product of leaf length, width and a leaf shape-specific correction factor. We validated our method by comparing leaf size estimates with those obtained from image recognition software and compared our approach with the widely used correction factor of 2/3. Key Results Correction factors ranged from 0.39 for highly dissected, lobed leaves to 0.79 for oblate leaves. Leaf size estimation using leaf shape-specific correction factors was more accurate and precise than estimates obtained from the correction factor of 2/3. Conclusion Our method presents a tractable solution to accurately estimate leaf size when only information on leaf length, width and shape is available or when labour and time constraints prevent usage of image recognition software. We see promise in applying our method to data from species descriptions (including from fossils), databases, field work and on herbarium vouchers, especially when non-destructive in situ measurements are needed. [ABSTRACT FROM AUTHOR]

Background and Aims While the 'worldwide leaf economics spectrum' (Wright IJ, Reich PB, Westoby M, et al. 2004. The worldwide leaf economics spectrum. Nature 428: 821-827) defines mineral nutrient relationships in plants, no unifying functional consensus links size attributes. Here, the focus is upon leaf size, a much-studied plant trait that scales positively with habitat quality and components of plant size. The objective is to show that this wide range of relationships is explicable in terms of a seed-phytomer-leaf (SPL) theoretical model defining leaf size in terms of trade-offs involving the size, growth rate and number of the building blocks (phytomers) of which the young shoot is constructed. Methods Functional data for 2400+ species and English and Spanish vegetation surveys were used to explore interrelationships between leaf area, leaf width, canopy height, seed mass and leaf dry matter content (LDMC). Key Results Leaf area was a consistent function of canopy height, LDMC and seed mass. Additionally, size traits are partially uncoupled. First, broad laminas help confer competitive exclusion while morphologically large leaves can, through dissection, be functionally small. Secondly, leaf size scales positively with plant size but many of the largest-leaved species are of medium height with basally supported leaves. Thirdly, photosynthetic stems may represent a functionally viable alternative to 'small seeds þ large leaves' in disturbed, fertile habitats and 'large seeds+ small leaves' in infertile ones. Conclusions Although key elements defining the juvenile growth phase remain unmeasured, our results broadly support SPL theory in that phytometer and leaf size are a product of the size of the initial shoot meristem = seed mass) and the duration and quality of juvenile growth. These allometrically constrained traits combine to confer ecological specialization on individual species. Equally, they appear conservatively expressed within major taxa. Thus, 'evolutionary canalization' sensu Stebbins (Stebbins GL. 1974. Flowering plants: evolution above the species level. Cambridge, MA: Belknap Press) is perhaps associated with both seed and leaf development, and major taxa appear routinely specialized with respect to ecologically important size-related traits. [ABSTRACT FROM AUTHOR]

Leaf-level anatomical variation is readily apparent within tall tree crowns, yet the relative importance of water and light availability in controlling this variation remains unclear. Sitka spruce (Picea sitchensis, (Bong.) Carr.) thrives in temperate rainforests of the Pacific Northwest, where it has historically reached heights >100m, despite rarely living more than 400 years alongside redwoods that are five times older. We examined leaves of trees up to 97m tall using a combination of transverse sections, longitudinal sections, epidermal imprints and whole-leaf measurements to explore the combined effects of water stress and light availability on leaf development in P. sitchensis. In contrast to the situation in tall Cupressaceae, light availability--not hydraulic limitation--is the primary ecological driver of leaf-level anatomical variation in P. sitchensis. While height-associated decreases in leaf length and mesoporosity are best explained by hydrostatic constraints on leaf elongation, the majority of anatomical traits we measured reflect acclimation to light availability, including increases in leaf width and vascular tissue areas in the brightest parts of the crown. Along with these changes, the appearance of abaxial stomata in the bright upper crown, and the arrangement of mesophyll in uniseriate, transverse plates--with radially arranged apoplastic pathways leading directly to stomata before bridging them with a V-shaped cell--may enhance gas exchange and hydraulic conductivity. This suite of leaf traits suggests an adaptive strategy that maximizes photosynthesis at the expense of water-stress tolerance. Anatomical investigations spanning the height gradient in tall tree crowns build our understanding of mechanisms underlying among-species variation in growth rates, life spans, and potential responses to climate change. [ABSTRACT FROM AUTHOR]

Leaf shape is one of the key determinants of plant architecture. Leaf shape also affects the amount of sunlight captured and influences photosynthetic efficiency; thus, it is an important agronomic trait in crop plants. Understanding the molecular mechanisms governing leaf shape is a central issue of plant developmental biology and agrobiotechnology. Here, we characterized the narrow-leaf phenotype of FL90, a linkage tester line of rice (Oryza sativa). Light and scanning electron microscopic analyses of FL90 leaves revealed defects in the development of marginal regions and a reduction in the number of longitudinal veins. The narrow-leaf phenotype of FL90 shows a two-factor recessive inheritance and is caused by the loss of function of two WUSCHEL-related homeobox genes, NAL2 and NAL3 (NAL2/3), which are duplicate genes orthologous to maize NS1 and NS2 and to Arabidopsis PRS. The overexpression of NAL2/3 in transgenic rice plants results in wider leaves containing increased numbers of veins, suggesting that NAL2/3 expression regulates leaf width. Thus, NAL2/3 can be used to modulate leaf shape and improve agronomic yield in crop plants. [ABSTRACT FROM AUTHOR]

A spatially explicit mechanistic model, MAESTRA, was used to separate key parameters affecting transpiration to provide insights into the most influential parameters for accurate predictions of within-crown and within-canopy transpiration. Once validated among Acer rubrum L. genotypes, model responses to different parameterization scenarios were scaled up to stand transpiration (expressed per unit leaf area) to assess how transpiration might be affected by the spatial distribution of foliage properties. For example, when physiological differences were accounted for, differences in leaf width among A. rubrum L. genotypes resulted in a 25% difference in transpiration. An in silico within-canopy sensitivity analysis was conducted over the range of genotype parameter variation observed and under different climate forcing conditions. The analysis revealed that seven of 16 leaf traits had a ≥5% impact on transpiration predictions. Under sparse foliage conditions, comparisons of the present findings with previous studies were in agreement that parameters such as the maximum Rubisco-limited rate of photosynthesis can explain ∼20% of the variability in predicted transpiration. However, the spatial analysis shows how such parameters can decrease or change in importance below the uppermost canopy layer. Alternatively, model sensitivity to leaf width and minimum stomatal conductance was continuous along a vertical canopy depth profile. Foremost, transpiration sensitivity to an observed range of morphological and physiological parameters is examined and the spatial sensitivity of transpiration model predictions to vertical variations in microclimate and foliage density is identified to reduce the uncertainty of current transpiration predictions. [ABSTRACT FROM PUBLISHER]

Background and Aims: Genotypic variation in tillering can be caused by differences in the carbon supply–demand balance within a plant. The aim of this study was to understand and quantify the effects of genotype on tillering as a consequence of the underlying internal competition for carbohydrates. [ABSTRACT FROM PUBLISHER]

We investigated adaptation of leaf morphology and physiology of red ironbark (Eucalyptus sideroxylon Cunn. Ex. Wools subsp. tricarpa L.A.S. Johnson) in a common garden experiment. Fifteen populations, representing a rainfall range of 500 to 1055 mm per annum at the sites of seed collection, were grown at the same site. Because environmental variables other than rainfall did not vary significantly among populations, we were able to test if leaf morphology and physiology were related to seed-source rainfall. There were large differences among and within populations in all measured variables. Most univariate relationships with seed-source rainfall were not significant. Notable exceptions were the weak positive correlation of specific leaf area with seed-source rainfall—consistent with expectations—and the weak negative correlation of photosynthesis and stomatal conductance with seed-source rainfall—the opposite of what we predicted. In many cases, populations collected from sites of similar rainfall differed greatly in leaf morphology and physiology. Principal component analysis (PCA) reduced the 13 input variables to five principal components (PC) explaining 73.0% of the total variance in the original data. Some of the PC axes could be interpreted in terms of adaptation to drought (i.e., to seed-source rainfall), but relationships of accumulated variables (the PC axes) with seed-source rainfall were significant for only one PC axis. Hence, among red ironbark populations grown in a common garden, there was significant genetic variation in leaf morphology and physiology, but for most traits, this variation was unrelated to rainfall at the site of seed collection. This study adds to a growing body of common garden literature showing weak within-species relationships of leaf morphology and physiology with seed-source rainfall, in contrast to the consistently stronger relationships among species growing at different points along broad environmental gradients. [ABSTRACT FROM AUTHOR]

• Background and Aims Rapid leaf area expansion is a desirable trait in the early growth stages of cereal crops grown in low‐rainfall areas. In this study, the traits associated with inherent variation in early leaf area expansion rates have been investigated in two wheat species (Triticum aestivum and T. durum) and three of its wild relatives (Aegilops umbellulata, A. caudata and A. tauschii) to find out whether the Aegilops species have a faster leaf area expansion in their early developmental stage than some of the current wheat species.• Methods Growth of individual leaves, biomass allocation, and gas exchange were measured on hydroponically grown plants for 4 weeks.• Key Results Leaf elongation rate (LER) was strongly and positively correlated with leaf width but not with leaf elongation duration (LED). The species with more rapidly elongating leaves showed a faster increase with leaf position in LER, leaf width and leaf area, higher relative leaf area expansion rates, and more biomass allocation to leaf sheaths and less to roots. No differences in leaf appearance rate were found amongst the species.• Conclusions Aegilops tauschii was the only wild species with rapid leaf expansion rates similar to those of wheat, and it achieved the highest photosynthetic rates, making it an interesting species for further study. [ABSTRACT FROM AUTHOR]

Growing leaves of tall fescue (Festuca arundinaceaSchreb.) were studied from emergence to a short time before the leaf ceases growth. Leaf form (width, average thickness, number of vascular bundles and height of associated ridges) and growth patterns were determined. The tissue elements produced at the point of leaf insertion are wider and thicker with time, as the intercalary meristem develops. These elements undergo further width and thickness changes as they traverse the elongation zone, and leaf width and average thickness can continue to increase after passing the elongation zone. In order to relate the generation of leaf form and dry matter (DM) deposition, three methods were used to describe DM fluxes: (1) we followed the path lines of material elements and determined that they accumulate DM as they are displaced away from leaf base, even when expansive growth and maturation are complete; (2) we calculated DM deposition on a unit length basis, which represents the total sink strength of the zone studied, and we deduced that the sink strength of the elongation zone increases with time, in concert with the changes in width and thickness of the elements that are successively produced at leaf base; (3) we calculated DM deposition on a unit volume basis, which represents the net metabolic activity of the zone considered, and we found that growth activity and associated DM deposition were high 3 d after the leaf emerged, then decreased gradually, whereas maturation and associated DM deposition were low at emergence, but increased as the leaf gradually became autotrophic. Our data indicate that different descriptors and measurements are needed during the totality of leaf growth.Copyright 1997 Annals of Botany Company [ABSTRACT FROM AUTHOR]