True Leaf Area Research Articles

CO2-assimilation, sequestration, and storage by urban woody species growing in parks and along streets in two climatic zones

Using two cities, Rimini (Italy, Cfa climate) and Krakow (Poland, Cfb), as living laboratories, this research aimed at measuring in situ the capacity of 15 woody species to assimilate, sequester, and store CO2. About 1712 trees of the selected species were identified in parks or along streets of the two cities, and their age, DBH, height, and crown radius were measured. The volume of trunk and branches was measured using a terrestrial LiDAR. The true Leaf Area Index was calculated by correcting transmittance measurements conducted using a plant-canopy-analyser for leaf angle distribution, woody area index, and clumping. Dendrometric traits were fitted using age or DBH as independent variable to obtain site- and species-specific allometric equations. Instantaneous and daily net CO2-assimilation per unit leaf area was measured using an infra-red gas-analyser on full-sun and shaded leaves and upscaled to the unit crown-projection area and to the whole tree using both a big-leaf and a multilayer approach. Results showed that species differed for net CO2-assimilation per unit leaf area, leaf area index, and for the contribution of shaded leaves to overall canopy carbon gain, which yielded significant differences among species in net CO2-assimilation per unit crown-projection-area (AcpaML(d)). AcpaML(d) was underestimated by 6–30 % when calculated using the big-leaf, compared to the multilayer model. While maximizing AcpaML(d) can maximize CO2-assimilation for a given canopy cover, species which matched high AcpaML(d) and massive canopy spread, such as mature Platanus x acerifolia and Quercus robur, provided higher CO2-assimilation (Atree) at the individual tree scale. Land use (park or street), did not consistently affect CO2-assimilation per unit leaf or crown-projection area, although Atree can decline in response to specific management practices (e.g. heavy pruning). CO2-storage and sequestration, in general, showed a similar pattern as Atree, although the ratio between CO2-sequestration and CO2-assimilation decreased at increasing DBH.

Genetic and molecular regulation of increased photosynthetic cell number contributes to leaf size heterosis in Arabidopsis

Heterosis is an important genetic phenomenon that has been observed and widely utilized in agriculture. However, the genetic and molecular bases of heterosis are unclear. Through transcriptome-wide association studies (TWAS) and expression quantitative trait locus (eQTL) analysis to integrate genome, transcriptome, and heterotic phenotype of a half-sibling Arabidopsis hybrid population, we report that the genetic and molecular bases of variations in leaf growth heterosis can be explained by the varied expression levels of growth-regulating genes resulting from distinct sets of heterozygous eQTLs carried by the half-sibling hybrids. In F1 versus parent, the degree of up-regulated gene expression in the cell cycle pathway in the shoot apex and the photosynthesis pathway in true leaf positively correlates with true leaf area heterosis level, and this is affected by the accumulation of superior heterozygous eQTLs. This was further corroborated by the major contribution of increased photosynthetic cell number to leaf area heterosis.

Growth response of oil palm seedling from decanter cake application as fertiliser substitute in nursery

Sustainable waste management is essential to safeguard the environment and corporate interests. Stringent regulations on quality of palm oil mill effluent (POME) discharge led to the introduction of more decanter machines, which increased output of dried POME solid namely oil palm decanter cake (OPDC). Therefore, a field experiment was planned to investigate how OPDC can be directly used as fertiliser for oil palm (OP) seedling to meet the needs of the plants. In polythene bags as planting media, topsoil was combined with OPDC at ratios of 10%, 20%, 30%, and 50%. This was followed by a reduction in inorganic fertiliser at levels of 25%, 50%, a predetermined nutrient deficiency input, and up to 100% for planting medium at a ratio of 50% OPDC to topsoil. Null hypothesis was tested by comparing vegetative development i.e., seedling’s girth, height, rachis length, frond production, petiole size and true leaf area at 3rd, 6th, and 9th month after planting (MAP). OP seedlings able to tolerate OPDC application up to 50% mixture ratio with topsoil from transplanting up to twelve months old of biological age. Growth response in treatments up to 50% and nil fertiliser input showed comparable results (P>0.005) against control in all parameters evaluated across three, six and nine months of growing period. Despite of full manuring input, OPDC application on OP seedlings has neither caused leaf phytotoxicity nor deficiency. In conclusion, OPDC can be applied directly to OP seedling as a fertiliser alternative with equal growth performance to standard method.

USE OF BITUMEN-TREATED FABRIC MULCH DURING FIRST YEAR REPLANTING OF IMMATURE OIL PALMS

The use of empty fruit bunch (EFB) mulching in oil palm replants has for decades been implemented as best practice across the industry. In this study, several trials were initiated to evaluate the effectiveness of bitumen-treated fabric mulch (BFM) as an alternative for EFB mulching on oil palm growth performance in replants. The trial was conducted in Jeleta Bumi Estate, Sabah for 12 months. The treatments evaluated were mulching using BFM with a total quantity of first-year fertiliser applied underneath (T1) and normal EFB mulching with the standard bi-monthly manuring programme (T2). The treatments were arranged using randomised complete block design (RCBD) with four replications. The palms’ rachis length, petiole cross-section, and total fronds were measured 12 months after planting to calculate the relative leaf area (RLA), true leaf area (TLA), and leaf area index (LAI). Leaves from frond number nine were sampled for nutrient analysis. Concurrently, these treatments were replicated at a semi-commercial scale in five estates totalling 466.36 hectares under T1. Generally, there was no significant difference (P>0.05) in all parameters measured for both vegetative performance and leaf nutrients between T1 and T2. Additionally, box plot analysis indicated a uniform growth pattern across treatments from the calculated RLA, TLA, and LAI. Cost-benefit analysis indicated a saving of up to 62 per cent at 12 months after planting. This includes costs of EFB transportation, weeding and manuring rounds. Concomitantly, labour dependency could be further reduced, particularly of interest under current industry labour shortages. Response by users highlighted in reduced road maintenance, minimised rhinoceros beetle damage and lower frond scorching.

Hardwood biochar as an alternative to reduce peat use for seed germination and growth of Tagetes patula

ABSTRACT Biochar, a carbon-rich material resulting from pyrolysation, is one of the proposed alternatives as a substrate component to peat. The aim of this study was to investigate the effect of different ratios of peat substitution with a locally available hardwood biochar on the chemical characteristics of growing media, seed germination, plant morphological and nutritional parameters of Tagetes patula. Experimental results show that biochar can be used as a partial peat replacement, showing a complementary liming effect, rising the initial pH of peat (2.8) to values of 4.5 and 7.3 in mixtures with 50% and 75% substitution of peat by biochar, respectively. The mixture with a 50% biochar rate exhibited the strongest change between initial and final pH, rising from 4.5 to 5.7. Increasing content of biochar in the mixtures corresponded to increasing content of total K, Ca, Mg, available K and decreasing level of available Mg. The highest germination percentage was observed in the mixtures with biochar rates from 50% to 100%. Among all substrates, the greatest plant diameter, true leaf area and total root length were measured in the 50% peat substitution mixture, where the highest contents of P, K and Ca in plant shoots were found.

Reassessing the estimation of leaf area in oil palm (Elaeis guineensis Jacq.) by linear regression equation

AbstractThe area of individual leaves in oil palm has been conventionally estimated from a regression equation that is based on the size and number of leaflets. The aim of the present study is to verify the accuracy of this equation, which became standard in oil palm research. Therefore, true leaf area, measured with a video camera, was estimated from the product of number of leaflets per leaf (n) with mean length (l) times mid-width (w) of six of the longest leaflets (nlw). The database was assembled, annually for the first 4 years after planting, from 2961 leaves of dura × pisifera testcrosses descending from six distinct pisifera origins. The regression coefficients of the regression lines of nlw plotted against true area did not show a trend with age of the palms or a difference among pisifera origins. The common regression equation fitted through all data of this study accurately estimated true leaf area of the testcrosses and also the areas of 2- to 3.5-year-old dura palms of three distinct origins as well as 18-year-old tenera palms. These outcomes are at odds with the conventional regression equation that overestimates the true leaf areas by about 24%. A more recently-developed variant underestimates true area of the young tenera and dura palms by 28%, while overestimating true area of old tenera palms by 19%. Possible causes for these deviations from true area are discussed. The paper argues that parameters depending on leaf area of previous physiological studies need to be reassessed.

Comparison of LiDAR-based Models for True Leaf Area Index and Effective Leaf Area Index Estimation in Young Beech Forests

The leaf area index (LAI) is one of the most common leaf area and canopy structure quantifiers. Direct LAI measurement and determination of canopy characteristics in larger areas is unrealistic due to the large number of measurements required to create the distribution model. This study compares the regression models for the ALS-based calculation of LAI, where the effective leaf area index (eLAI) determined by optical methods and the LAI determined by the direct destructive method and developed by allometric equations were used as response variables. LiDAR metrics and the laser penetration index (LPI) were used as predictor variables. The regression models of LPI and eLAI dependency and the LiDAR metrics and eLAI dependency showed coefficients of determination (R2) of 0.75 and 0.92, respectively; the advantage of using LiDAR metrics for more accurate modelling is demonstrated. The model for true LAI estimation reached a R2 of 0.88.

Associations between first true leaf physiology and seedling vigor in cotton under different field conditions

AbstractRapid development of the first true leaf has been suggested as a key driver of seedling vigor in cotton, yet studies demonstrating an association between first true leaf physiological processes and early season cotton growth are limited. It was hypothesized that both first true leaf area (FTLA) and photosynthetic rates would be positively associated with cotton (Gossypium hirsutumandG. barbadense) seedling vigor, and that photosynthetic component processes would differ in their contribution to net photosynthesis (An) of the first true leaf. To test these hypotheses, three different cotton cultivars were planted in the 2017 and 2018 seasons on three selected dates each year to generate broad differences in seedling vigor. Growth analysis was conducted to assess seedling vigor at 3 and 5 wk after planting, and a combination of dark‐ and light‐adapted gas exchange and fluorescence measurements were performed on the first true leaf, concurrent with growth assessments. Seedling vigor was much more strongly associated with FTLA than Anon a per unit leaf area basis, suggesting that FTLA was a stronger indicator of seedling vigor. Correlation analysis between Anand a number of component processes derived from combined gas exchange and fluorescence measurements indicated that Anwas strongly correlated with electron transport rates and stomatal conductance. However, we suggest that most of the variability we observed in Anof the first true leaf was primarily driven by nonstomatal factors, since no significant correlations between Anand chloroplast CO2concentration or substomatal CO2concentration was apparent.

Impact of First True Leaf Photosynthetic Efficiency on Peanut Plant Growth under Different Early-Season Temperature Conditions

ABSTRACT Selecting planting dates with optimal temperatures for plant growth and development is important for successful crop production. Photosynthetic rates of peanut leaves under adverse environmental conditions have been widely studied; however, characterization of photosynthetic efficiency of first true leaves as well as its contribution to plant growth is not well elucidated. The objectives of this research were to assess the influence of first true leaves of peanut cultivars on plant growth under different temperature conditions during early growth and at the onset of flowering and to identify the photosynthetic components more closely linked with photosynthetic efficiency of the first true leaves. Experiments were conducted with April (early), May (optimum), and June (late) planting dates in 2017 and 2018. Cultivars Georgia-06G, Georgia-14N, and TifNV-High O/L were evaluated. Measurements were taken at three and five wks after planting, early season and the onset of flowering, respectively. Rapid development of first true leaves of peanut plants contributed to whole-plant growth in the early season and at the onset of flowering across the temperature conditions. Net photosynthesis of first true leaves was not impacted by temperature conditions in the early season or at the onset of flowering primarily due to greater activity of non-stomatal components associated with the thylakoid reactions. Whole-plant growth was more considerably associated with first true leaf area development than photosynthetic efficiency of those leaves in peanut plants.

Estimating leaf area of Jatropha nana through non-destructive allometric models

Jatropha nana is an endemic, threatened under-shrub possessing significant economic potential. In spite of this economic importance, there has been no allometric equation described till date to estimate its leaf area. We address this lacuna by describing a method of estimating the leaf area directly, without using expensive leaf meters. For the two leaf morphotypes of J. nana (monolobed and trilobed), developing and mature leaves were collected from field and an allometric relationship was developed, using length (L), width (W) and LW as independent variables. For the described equations, the coefficient of determination (R a 2 ) between true leaf area and leaf dimensions ranged from 0.8356 to 0.9963. After applying certain statistical criteria we report that the equations Ŷ = 0.6942*(LW) and Ŷ = 0.6426*(LW) are the best for estimating the monolobed and trilobed leaf area respectively. These equations could be further simplified by considering only one leaf dimension (W). Thus the equation Ŷ = 1.2890*(W) 1.8794 for monolobed leaves and Ŷ = 1.1089*(W) 1.8030 for trilobed leaves estimate leaf area of J. nana with high precision, accuracy, random dispersion pattern of residuals and without any bias. These equations will be vital for addressing several further questions on this under-researched species.

Characterizing Olive Grove Canopies by Means of Ground-Based Hemispherical Photography and Spaceborne RADAR Data

One of the main strengths of active microwave remote sensing, in relation to frequency, is its capacity to penetrate vegetation canopies and reach the ground surface, so that information can be drawn about the vegetation and hydrological properties of the soil surface. All this information is gathered in the so called backscattering coefficient (σ0). The subject of this research have been olive groves canopies, where which types of canopy biophysical variables can be derived by a specific optical sensor and then integrated into microwave scattering models has been investigated. This has been undertaken by means of hemispherical photographs and gap fraction procedures. Then, variables such as effective and true Leaf Area Indices have been estimated. Then, in order to characterize this kind of vegetation canopy, two models based on Radiative Transfer theory have been applied and analyzed. First, a generalized two layer geometry model made up of homogeneous layers of soil and vegetation has been considered. Then, a modified version of the Xu and Steven Water Cloud Model has been assessed integrating the canopy biophysical variables derived by the suggested optical procedure. The backscattering coefficients at various polarized channels have been acquired from RADARSAT 2 (C-band), with 38.5° incidence angle at the scene center. For the soil simulation, the best results have been reached using a Dubois scattering model and the VV polarized channel (r2 = 0.88). In turn, when effective LAI (LAIeff) has been taken into account, the parameters of the scattering canopy model are better estimated (r2 = 0.89). Additionally, an inversion procedure of the vegetation microwave model with the adjusted parameters has been undertaken, where the biophysical values of the canopy retrieved by this methodology fit properly with field measured values.

Characterizing Olive Grove Canopies by Means of Ground-Based Hemispherical Photography and Spaceborne RADAR Data

One of the main strengths of active microwave remote sensing, in relation to frequency, is its capacity to penetrate vegetation canopies and reach the ground surface, so that information can be drawn about the vegetation and hydrological properties of the soil surface. All this information is gathered in the so called backscattering coefficient (s0). The subject of this research have been olive groves canopies, where which types of canopy biophysical variables can be derived by a specific optical sensor and then integrated into microwave scattering models has been investigated. This has been undertaken by means of hemispherical photographs and gap fraction procedures. Then, variables such as effective and true Leaf Area Indices have been estimated. Then, in order to characterize this kind of vegetation canopy, two models based on Radiative Transfer theory have been applied and analyzed. First, a generalized two layer geometry model made up of homogeneous layers of soil and vegetation has been considered. Then, a modified version of the Xu and Steven Water Cloud Model has been assessed integrating the canopy biophysical variables derived by the suggested optical procedure. The backscattering coefficients at various polarized channels have been acquired from RADARSAT 2 (C-band), with 38.5° incidence angle at the scene center. For the soil simulation, the best results have been reached using a Dubois scattering model and the VV polarized channel (r2 = 0.88). In turn, when effective LAI (LAIeff) has been taken into account, the parameters of the scattering canopy model are better estimated (r2 = 0.89). Additionally, an inversion procedure of the vegetation microwave model with the adjusted parameters has been undertaken, where the biophysical values of the canopy retrieved by this methodology fit properly with field measured values.

Evaluation of four methods for estimating leaf area of isolated trees

The accurate modeling of the physiological and functional processes of urban forests requires information on the leaf area of urban tree species. Several non-destructive, indirect leaf area sampling methods have shown good performance for homogenous canopies. These methods have not been evaluated for use in urban settings where trees are typically isolated and measurement may be complicated by proximity to residential areas, buildings, signs, and other infrastructure elements. We evaluated the accuracy, precision, efficiency and other practical considerations associated with four methods of estimating the leaf area of open-grown deciduous trees in urban forests. The methods included color digital image processing (CD), the LAI-2000 Plant Canopy Analyzer, the CI-100 Digital Plant Canopy Imager, and a logarithmic regression equation. Regression coefficients, adjusted R 2, and confidence intervals were used to determine the best method when using true leaf area of 25 Platanus x acerifolia Willd. and 25 Platanus racemosa Nutt. as an independent variable. Practical considerations included ease of data collection and processing and costs associated with each method. The CD method and LAI-2000 estimates showed good correlation with true leaf area (R 2 ≫ 0.71); however, only the CD method produced estimates within 25 percent of mean true leaf area and met additional requirements for accuracy, precision, and efficient use in urban settings.

Estimativa da área foliar de plantas daninhas de ambiente aquático: Eichhornia crassipes

O objetivo deste trabalho foi obter equações que, através de parâmetros lineares dimensionais do limbo e do pecíolo, permitam estimar a área foliar do limbo e a área externa do pulvino de Eichhornia crassipes. Para isso, estudaram-se correlações entre a área foliar real e os parâmetros dimensionais do limbo foliar, como o comprimento ao longo da nervura principal (C) e a largura máxima (L) perpendicular ao eixo principal, assim como correlações entre a área externa real e o comprimento máximo (CP) e o maior diâmetro transversal (DP) do pulvino. Todas as equações lineares simples, geométricas ou exponenciais permitiram boas estimativas da área foliar e área externa do pecíolo. Do ponto de vista prático, sugere-se optar pela equação linear simples envolvendo os respectivos produtos do comprimento pela largura máxima, considerando o coeficiente linear igual a zero. Desse modo, a estimativa da área foliar do limbo (AF) de E. crassipes pode ser feita pela fórmula AF = 0,720 (C x L); e a área externa do pulvino (AP) pode ser estimada pela fórmula AP = 2,378 (CP x DP), com coeficientes de determinação (R²) de 0,9716 e 0,9268, respectivamente.

The effect of tillage regime, row spacing, and seeding rate on feeding damage by flea beetles, Phyllotreta spp. (Coleoptera: Chrysomelidae), in canola in central Alberta, Canada

Feeding damage by the flea beetles, Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae), was assessed on Polish ( Brassica rapa L.) and Argentine ( Brassica napus L.) canola grown under conventional and zero tillage regimes, with three different row spacings (10, 20, and 30 cm) and three seeding rates (5.0, 7.5, and 10.0 kg ha -1 or 120, 180, and 240 plants m -2). The studies were conducted during three field seasons (1994, 1995, and 1996) at Vegreville in central Alberta, Canada. Flea beetle damage was determined when plants were in the seedling stage by estimating the percentages of cotyledon and true leaf area eaten by the insects. Plants of B. rapa were consistently damaged to a greater degree than were plants of B. napus. In all three years of study, significantly greater damage was caused to plants of both species of canola grown in a conventional tillage regime compared with a zero tillage regime. Treatment effects of row spacing and seeding rate on flea beetle damage were more variable. In 1994 and 1996, statistically significant reductions in plant damage occurred with an increase in seeding rate and row spacing for both species of canola; however, these differences were not significant for either canola species in 1995. Results of our study suggest that seed treatment with the insecticide lindane, used routinely in central Alberta to reduce herbivory by flea beetles, is probably not necessary in this region when canola is grown under a zero-till regimen. Regardless of tillage regime, our regression analyses determined that flea beetle damage can be reduced by increasing seeding rates and row spacings from those currently recommended for canola production, a practice that is also compatible with reducing crop damage from other important canola pests.

Non-destructive determination of leaf area in tomato plants using image processing

SummaryThe objectives of this study were to validate the use of image processing for the measurement of leaf areas in intact tomato plants and to examine the potential of taut- string bounding area as a parameter for wilting. This was achieved by taking images of 18 tomato plants, viewed from the top, from the side and from an oblique angle. In the case of side and oblique views the images were taken as the plant was rotated through 360° with 45° steps. An average value of the leaf area was then calculated for each view. Regression of true leaf area on image-calculated areas for individual views resulted in a second order polynomial which adequately described the relationship. The regression coefficient, R2, adjusted for degrees of freedom, was 0.98. Multiple regression of true leaf area against areas obtained from two views increased R2 to 0.99. When all three view points were taken into consideration, R2 increased further, albeit modestly, to 0.993. Taut-string boundary provides information about the plant’s compactness as it grows. A boundary was obtained by rotating the image co-ordinate system through 16 different angles. After every rotation the extreme points of the image were determined. These points formed the corners of a bounding polygon that approximated to the taut string boundary. The polygon area was calculated from the co-ordinates of the polygon corners. Regression of true leaf area on taut string image area for individual views resulted in a second-order polynomial which adequately described the relationship. Multiple regression improved the regression coefficient. To test the potential usefulness of taut-string area, two plants were water stressed, then irrigated and monitored while they recovered from wilted to turgid. The change in taut string area detected (50–55%) was sufficient to recommend its use as a meaningful parameter for wilting.

Correcting leaf area measurement by conventional methods: a new approach for apple(Malus domesticaBorkh)

Conventional techniques for leaf area measurement, although non-destructive and capable of handling large samples, often produce values widely different from true leaf areas. Parameter values estimated by conventional methods can be corrected with a high degree of accuracy by using correction factors. The present investigation evaluates the significance of factors derived for two common conventional methods and ten apple cultivars. The studies were carried out between 1983 and 1989 at three locations in District Tehri Garhawl, India, on mature fruiting trees of ten commercial apple cultivars. Leaf samples were selected randomly and leaf areas determined by eight methods. The estimated parameter values were assessed statistically and compared with the true leaf area, as measured by planimeter, to test their reliability. The estimated leaf area corrected by derived constant factors in two conventional methods (leaf area determination by L x W and fresh weight) showed a high degree of accuracy and both const...

Estimating leaf area of plantain

The area of leaves of plantain (Musa acuminata × Musa balbisiana) was traced on graph paper. Then the length ( L) and the maximum width ( W) were measured. A known leaf area from each leaf was taken and both the sample and the remaining leaf blades were dried and weighed. Using known leaf area and their dry weights, the leaf area of each whole leaf was determined. From the regression equation, a coefficient for estimating the true leaf area from the L × W measurements was determined to be 0.8 (approx.) which was statistically significant ( P = 0.05). Using a mathematical method (independent of the first method), the coefficient for estimating the true leaf area of plantain was found to be 0.7854. A significant correlation ( r, 0.001 = 0.73) was also found between the area traced on graph paper and that determined using the coefficient 0.8 ( L × W).

Seedling and Yield Response of Cucumber to Naptalam and Chloramben

Height, true-leaf area, shoot dry weight, and survival of the seedlings of four varieties of cucumber (Cucumis sativusL.) were measured for differences occurring when treated preemergence with naptalam (N-1-naphthylphthalamic acid) alone, chloramben (3-amino-2,5-dichlorobenzoic acid) methyl ester alone, or with combinations of these two herbicides. These factors were reduced, depending upon the variety of cucumber, with each of the herbicide treatments. The only reduction associated with naptalam alone was the true-leaf area of ‘Model’ and ‘Wisconsin SMR 58.’ ‘Ohio MR 17,’ ‘Model,’ and ‘Wisconsin SMR 58’ had less reduction of all measured responses than ‘Pixie’ when treated with chloramben methyl ester alone or with combinations of naptalam and chloramben methyl ester. The herbicide variety interactions present in seedling injury under greenhouse conditions were not reflected in the yields of these varieties when grown in the field. The only significant yield reduction occurring under field conditions was with the 4.48 kg/ha rate of chloramben methyl ester in the first harvest.