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The generation of morphological traits of plants such as the leaf length, width, perimeter, area, and petiole length are fundamental features of herbarium specimens, thus providing high-quality data to investigate plant responses to ongoing climatic change and plant history evolution. However, the existing measurement methods are primarily associated with manual analysis, which is labor-intensive and inefficient. This paper proposes a deep learning-based approach, called Deep Leaf, for detecting and pixel-wise segmentation of leaves based on the improved state-of-the-art instance segmentation approach, Mask Region Convolutional Neural Network (Mask R-CNN). Deep Leaf can accurately detect each leaf in the herbarium specimen and measure the associated morphological traits. The experimental results indicate that our automated approach can segment the leaves of different families. Compared to manual measurement done by ecologist and botanist experts, the average relative error of leaf length is 4.6%, while the average relative error of leaf width is 5.7%.

The aim of this study was to examine the feasibility of noncoplanar volumetric modulated arc stereotactic radiotherapy (VMAT-SRT) using a 5-mm multileaf collimator (MLC) for multiple brain metastases. We identified 34 multiple-target cases (3 to 19 targets in each case) with a total of 257 of targets and constructed noncoplanar VMAT-SRT plans using 5-mm and 2.5-mm MLCs with 4-arc. The prescribed dose was 36 Gy/6 fr. Plans were evaluated using the Paddick conformity indices (PCI), Paddick gradient index (PGI), and normal brain dose (NBD, equal to the mean brain dose minus gross tumor volume). There were no significant differences in PCI (median [range]: 5 mm, 0.88 [0.78 to 0.94]; 2.5 mm, 0.89 [0.78 to 0.94]; p= 0.691), PGI (median [range]: 5 mm, 3.96 [2.21 to 6.63]; 2.5 mm, 3.96 [2.24 to 6.45]; p= 0.358), or NBD (median [range]: 5 mm, 7.5 Gy [2.5 to 12.4]; 2.5 mm, 7.5 Gy [2.5 to 12.5]; p= 0.675). The performance of the 5-mm MLC was not inferior to the 2.5-mm MLC in applications of noncoplanar VMAT-SRT for multiple brain metastases with regards to dose conformity, gradient, and NBD. This study provides the necessary background for generalizing noncoplanar VMAT-SRT approaches in treating multiple brain lesions.

Camelina [Camelina sativa (L.) Crantz] has two distinctive biotypes, summer and winter, with winter biotypes requiring a vernalization treatment to enter the reproductive phase. Increased interest in broadening the diversity of winter-hardy cover crops in the northern Great Plains of the U.S. to reduce soil erosion through the winter months has led seed companies to offer winter camelina seed outsourced from other states. Regrettably, in 2017, outsourced camelina seed from other states turned out to be summer biotypes that did not survive the North Dakota winter. The objectives of this study were to determine the morphological characteristics of seed and seedlings from summer- and winter-biotypes. Morphological characteristics of seedlings were determined by growing nineteen summer- and eleven winter-biotypes in an environmental chamber. The experimental design was a randomized complete block design with three replicates. To determine differences in seed wavelength absorbance between winter- and summer-biotypes both visible and near infrared spectra were examined, which encompass 400–2498 nm wavelengths. Mixtures of cultivars Joelle (winter) and one summer type were analyzed using near infrared spectroscopy (NIRS). Seed mixtures were prepared in increments of 5% of ‘Joelle’. Mixtures of different lots of Joelle were prepared in increments of 25%. Significant interactions were present and observed for pairs of vegetative leaves, growth stage, height, leaf length, leaf width and the number of lobes. The equation for the ratio of winter seed (r2 = 0.96) performed very well, being able to distinguish known field grown cultivars used in the equation. Differences in seed and seedling morphological characteristics can be used to differentiate winter- or summer-biotypes. Having a rapid method to determine the percentage of winter camelina in an unknown seed sample will be very favorable for all producers, as well as seed companies, interested in growing winter camelina as either a winter-hardy cover crop or as a winter annual cash crop.

Leaf area (LA) and leaf mass (LM) are key parameters for predicting plant growth, but empirical models for measuring LA and LM at the leaf scale in different broadleaf species of saplings and adult trees across growing periods have rarely been proposed. Here, we collected leaf samples from saplings and adult trees of eight temperate broadleaf tree species during three growing periods (i.e., May, July and September) in northeastern China. For each leaf sample, we measured LA, LM and some leaf structure parameters (e.g., leaf length, L, and leaf width, W). We calculated the leaf length:width ratio (L:W). Afterwards, the data from the eight broadleaf tree species were classified into two categories by L:W and then tested to determine whether life history and growing period had a significant influence on developing the empirical models. Finally, we developed combined empirical models for predicting the LA and LM of saplings and adults of different broadleaf tree species across growing periods. The results showed that both life history and growing period generally had a more significant effect on predicting LM than LA for the two L:W categories. Generally, the forecast accuracy of these combined empirical models in predicting the LA and LM of the saplings and adults of most species across growing periods ranged from 83% to 93% and from 76% to 82%, respectively. In addition, the combined empirical models of the saplings or adults were suitable for predicting the LA and LM of six shrub species with maximum forecast accuracies of 93% and 85%, respectively, indicating that our developed combined empirical models were generally effective in predicting LA and LM in other broadleaf species. Furthermore, the optimum number of leaf samples ranged from 11 to 14 for LA and from 59 to 62 for LM, with forecast accuracies all greater than 97% for the broadleaf species.

Pyrus boissieriana appears to be a promising species for its use as rootstock for the commercial pear (P. communis L.) in lowland areas prone to drought and flooding. The current study was conducted on the evaluation of phenotypic diversity among 102 accessions of wild pear (P. boissieriana). The accessions studied showed significant differences in terms of all the measured characters. The leaf length ranged from 19.33 to 51.33 mm and leaf width varied from 17.13 to 48.75 mm. The fruit length ranged from 8.26 to 22.51 mm and the range of 10 fruit weight was from 2.48 to 72.00 g. Fruit weight showed positive correlations with bunch length, bunch weight, fruit length, and fruit width. Principal component analysis (PCA) showed that the first eight PCs explained 80.47% of the total variance and the characters such bunch weight, fruit length, fruit width, fruit diameter, fruit weight, and fruit flesh length were the key characters in the present data set, which differentiated the accessions belonging different areas. The dendrogram obtained based on the measured characters grouped the accessions into three main clusters and indicated the existence different levels of morphological variation among the accessions, which is applicable and useful for pear breeding programs. The finding obtained here confirmed that the northern and northeastern parts of Iran are rich sources of pear genetic diversity which this valuable gene pool should be in situ and ex situ conserved.

The aims are (1) to present a clinical brain case where the dose distribution calculated at 2.5-mm grid resolution was significantly different from that of 1.0 mm with Varian HD120 multileaf collimator (MLC; 2.5-mm central leaf width), and (2) to present our analysis results to better understand the influence of dose calculation grid resolution and its spatial alignment with MLC. A simulation using a static MLC pattern with 10 open strips was conducted to demonstrate the possibility that the characteristics of MLC dose profiles can be completely hidden. The effects of the spatial MLC alignment with the dose grid were investigated for grid resolutions from 1.0 mm to 5.0 mm. In the end, 20 recent stereotactic radiotherapy plans (5 brain, 5 lung, 5 spine, and 5 other) were retrospectively selected, and their dose distributions were recalculated at 1.0 mm, 1.5 mm, and 2.5 mm resolutions for comparisons. Film dosimetry results were used as references. At 2.5-mm grid resolution, the MLC open-strip patterns were not visible in the dose distribution when the MLC leaf interspaces were at exact alignment with the dose grid. The effects were smaller at 1.0-mm grid resolution. The dose error at the centers of the open strips varied significantly (7% to 39%) depending on the alignments. Overall, the planning target volume mean dose of 1.5-mm plans was higher than 1.0-mm plans by 1.3 ± 0.3% (mean ± 1SD) with a maximum of 2.6%, while the mean dose of 2.5-mm plans was lower by −0.5 ± 0.5% with a maximum mean dose of −3.7%. In conclusion, the choice of dose calculation grid resolution can affect the plan dose distribution significantly. The dose grid resolution must be smaller than the width of MLC leaf at a minimum. A finder resolution is expected to produce less uncertainty in the calculated dose and influenced less by the MLC-grid spatial alignment.

CO2 capture and storage (CCS) is an important technical strategy to reduce global CO2 emission from heavy industries. However, the risk of CO2 leakage in CCS-related projects cannot be ignored and it is crucial to identify and monitor CO2 leakage in CCS project areas in a timely and effective manner. So here we investigate the biological characteristics (plant height, leaf length, leaf width and SPAD value) and leaf spectral characteristics of maize under soil CO2 concentration of 10, 30, and 50%, with normal soil condition as control (CK). By analysing the original spectrum and first derivative spectrum of maize leaves, spectral parameters relatively sensitive to soil CO2 stress were extracted. Further, eight composite spectral characteristic indexes that are expected to identify CO2 leakages were constructed and analyzed. Besides, the normalized pigment chlorophyll index (NPCI) and modified chlorophyll absorption in reflectance index (MCARI) were also investigated for the indication role in CO2 leakage. The results showed that maize morphological traits had a significant hysteresis effect for the indication of CO2 leakage; the SPAD value was difficult to indicate the lower concentration of soil CO2 early. But it was found that three spectral characteristic indexes REP-BEP, RGP/RRV and RGP-RRV/RGP+RRV can effectively identify CO2 leakage, and three spectral characteristic indexes (RVP-GPP, REP-BEP and MCARI) can be used for quantitative inversion of soil CO2 concentration. Especially, REP-BEP index could both indicate CO2 leakage and quantitatively inverse soil CO2 concentration. In sum, the spectral characteristic indexes of maize leaves can be used as effective indicators to quickly and effectively identify CO2 leakage and quantitatively invert the CO2 concentration in soil.

This systematic determination of morphological and phytochemical data was conducted with the purpose of conserving and identifying the phylogenetic relationship among the Vanilla species of the Totonacapan region in Mexico to increase awareness of the genetic biodiversity. Samples of Vanilla planifolia, V. planifolia cv. “oreja de burro”, V. pompona, V. insignis, and V. inodora, are distributed across 19 municipalities of the State of Veracruz and 19 municipalities of the State of Puebla. Morphological data parameters were determined in situ and included leaf length, leaf width, leaf thickness, stem diameter, stem thickness, node distance, stem texture degree, flower colour intensity, and fruit length. Similarly, alkaloids, tannins, saponins, phenols, flavonoids, and terpenes were determined by specifically phytochemical tests and quantified by thin layer chromatography. Both, morphological and phytochemical data parameters, were successfully used in assembling dendrograms by using the Euclidian distance method and by principal component analysis. Keywords: Dendogram, Morphological data, Phylogenetic relationships, Phytochemical data, Principal component analysis, Vanilla sp

It is believed that black mulberry (Morus nigra) is a healthier fruit among mulberry species due to its high bioactive content. In the present study, the morphological and chemical variabilities of this species were investigated. There were statistical differences in terms of the morphological and chemical traits between the genotypes. Out of 37 morphological and seven chemical characters, 20 morphological and five chemical traits showed a coefficient of variation (CV) greater than 20.00%, indicating a high variability between the genotypes for these traits. The fruit weight varied between 1.79 and 5.69 g with an average of 3.85 g. The highest TSS content was 24.80%, while the lowest TSS was 11.20%, with an average of 18.42. The content of total anthocyanins was found between 57.62 and 475.65 mg CGE 100 g−1 FrWe. Total phenols ranged from 232.27 to 1777.73 mg GAE 100 g−1 FrWe. The fruit weight showed positive correlations with tree growth vigor, leaf length and leaf width. In addition, fruit weight was positively correlated with fruit length and fruit width. Furthermore, TSS was positively correlated with phenolic content and flavonoid content. The results obtained from the hierarchical grouping analysis separated genotypes into three and two main groups based on morphological and chemical characters, respectively. The present study increased knowledge about the phenotypic variation and phytochemical properties of black mulberry fruits and can be useful for producers, breeders, and processors.

To accelerate the mulberry breeding program and examine the genome size and ploidy levels of 27 mulberry accessions of promising lines in Taiwan, nuclei suspensions were prepared from unfolded young leaves and analyzed by a flow cytometer. The genome size of each accession was estimated by referring to the standard genome size of chicken erythrocyte nuclei (CEN, 2.5 pg). Our results indicated that 25 among 27 investigated accessions in M. bombycis, M. alba, M. latifolia, M. australis, M. formosnensis, and M. atropurpurea are diploids with genome sizes ranging from 0.61 to 0.71 pg. ‘Elongated mulberry No. 1’ (M. laevigata) with a genome size of 1.06 pg is a triploid. Two populations were identified in the accession ‘67C001’ (M. australis Poir.) with a genome size of either 0.63 pg or 0.98 pg. Due to their similarity in appearance, we suspected that they are probably from the same origin, thus warranting further investigations. Several important vegetative characters of diploids and triploids have been estimated, including leaf length, leaf width, petiole length, petiole width, leaf thickness, and internode length, to document their correlation using the unpaired t-test. Subsequently, the statistical relationship between diploid and triploid species on some of these important characters, including leaf width, petiole width and internode length, was determined through binary regression analysis. We suggested that the internode length could provide a beneficial index to distinguish individuals with different ploidy levels in the field. Results of this study provide useful information to clarify the taxonomy of Morus and improve breeding programs aiming to advance horticulture and sericulture.

Present study was undertaken to evaluate different morphological traits of rice advance lines. The experiment was laid out in randomized complete block design (RCBD) with ten rice advance lines replicated three times at National Tea and High Value Crops Research Institute (NTHRI) Shinkiari, Mansehra, Pakistan. Three plants per plot were selected randomly to record the important agro-morphological data viz. plant height, panicle length, number of tillers per plant, branches per panicle, flag leaf length, flag leaf width, flag leaf area, grain length, grain width and length/breadth (L/B) ratio were measured. All the recorded data was analyzed through SPSS 16.0 and Statistix 8.1. The results revealed that the vegetative growth attributes i.e. plant height was significantly increased in FH10-2 (152.7 cm), No. of tillers in FH4-1 (4.3), No. of branches in JP-6 (24.33), panicle length in Line 2(24) (49.6 cm), flag leaf length in FH10-2 (50.7 cm), flag leaf width in Super NPT-3 (4.3 cm) and flag leaf area in FH4-1 (143.6 cm), respectively. Furthermore, yield contributing attributes like grain length (8.5 mm) and Length/Breadth ratio (4.7) were significantly increased in FH4-1 and grain breadth in Super NPT-3 (2.8 mm). Among ten advance lines of rice, nine were recorded with slender grain shape while four advance lines were recorded with extra long slender and long slender grain size each.

CO2 capture and storage (CCS) is an important technical strategy to reduce global CO2 emission from heavy industries. However, the risk of CO2 leakage in CCS-related projects cannot be ignored and it is crucial to identify and monitor CO2 leakage in CCS project areas in a timely and effective manner. So here we investigate the biological characteristics (plant height, leaf length, leaf width and SPAD value) and leaf spectral characteristics of maize under soil CO2 concentration of 10, 30, and 50%, with normal soil condition as control (CK). By analysing the original spectrum and first derivative spectrum of maize leaves, spectral parameters relatively sensitive to soil CO2 stress were extracted. Further, eight composite spectral characteristic indexes that are expected to identify CO2 leakages were constructed and analyzed. Besides, the normalized pigment chlorophyll index (NPCI) and modified chlorophyll absorption in reflectance index (MCARI) were also investigated for the indication role in CO2 leakage. The results showed that maize morphological traits had a significant hysteresis effect for the indication of CO2 leakage; the SPAD value was difficult to indicate the lower concentration of soil CO2 early. But it was found that three spectral characteristic indexes REP-BEP, RGP/RRV and RGP-RRV/RGP+RRV can effectively identify CO2 leakage, and three spectral characteristic indexes (RVP-GPP, REP-BEP and MCARI) can be used for quantitative inversion of soil CO2 concentration. Especially, REP-BEP index could both indicate CO2 leakage and quantitatively inverse soil CO2 concentration. In sum, the spectral characteristic indexes of maize leaves can be used as effective indicators to quickly and effectively identify CO2 leakage and quantitatively invert the CO2 concentration in soil.

Leaves are a significant component of the shoot system in grasses, functioning in light capture and photosynthesis. Leaf width, length, and angle are expressions of development that collectively define canopy architecture. Thus, the distinctive morphology of grass leaves is an interdependent readout of developmental patterning and growth along the proximal-distal, medial-lateral, and adaxial-abaxial axes. Here, we review the chronology of patterning and growth, namely along the proximal-distal axis, during maize leaf development. We underscore that patterning and growth occur simultaneously, making use of shared developmental gradients and molecular pathways.

Non destructive estimation of leaf area is necessary for taking successive observations on the same leaf. Usually, a common method for developing leaf area estimation models was to execute regression analysis by taking leaf area as dependant variable and leaf parameters as independent variables. However, the regression analysis applicable only when there is a relation between dependent and independent variables. Therefore, the objective of this work was to develop an artificial neural network (ANN) model including leaf length and leaf width as inputs and to make comparison with regression models. Leaf area (LA) of Durain (Durio zibethinus) was estimated by ANN and regression models. Among the linear regression models (LRM), the equation LA = 0.888 (L*W) − 4.961 (R2 = 0.91, MSE = 5.17) was found to be the best fitting for durian. In ANN modelling best fitting results were obtained with two input nodes (leaf length and leaf width), one hidden layer, and one output layer (leaf area) as 2-1-1. Based on the values of root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE) and coefficient determination (R2), ANN model was found to be more accurate both in terms of training (R2 = 0.96, RMSE = 3.77, MAE = 2.41 and MAPE = 7.77) and testing phases (R2 = 0.94, RMSE = 4.81, MAE = 2.91 and MAPE = 0.05) than the best fitting regression model. Hence ANN method may be used as an alternative or supportive model in the estimation of leaf area of durian.

Artificial neural network (ANN) is applied for many subjects in agricultural science such as: crop yield and evapotranspiration prediction, soil parameters estimation, water demand forecasting, hydrological forecasting. Leaf area is one of parameters that is used to assess the plant vegetative growth. In this study, leaf areas of 61 plant species with different leaf shapes were estimated by ANNs and the effect of input data and pre-processing methods on ANNs performance was assessed. Results showed that the ANNs could provide good estimation of leaf area. ANNs input variable combination affected the ANNs performance to estimate the leaf area. With increase in number of hidden layers the epochs decreased and accuracy of the leaf area prediction and running speed increased. Results of test data set showed that MinMax pre-processing method resulted in more accurate prediction in comparison with the no pre-processed method and Norm STD method. The most conclusive result of this study is the application of ANNs for all of plant species, whereas, in application of other methods: specific equation should be prepared for each plant.

Polysaccharide, the main component of Polygonatum kingianum, has been proven to have many pharmacological effects, such as antioxidant, anti-aging and anti-bacteria. The accumulation of polysaccharides was greatly influenced by the growth age of P. kingianum. Therefore, a fast and low-cost chemometric method is needed to identify the growth age. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) and ultraviolet visible (UV-Vis) spectroscopy of P. kingianum with four growth ages (80 samples) were collected and analyzed by chemometric methods. The correlation between 13 agronomic traits and polysaccharide accumulation was discussed. A data fusion strategy was used to identify the growth age of P. kingianum by extracting the latent variables (LVs) and principal components (PCs) of the spectra. The results founded that the polysaccharide content showed a negative correlation the fibrous root number, leaf length, leaf width, stem diameter and fresh weight on the ground part. The ATR-FTIR and UV-Vis spectra in P. kingianum with different growth ages were similar. The regions of 1750–1500 cm−1, 1000–750 cm−1 and 200–250 nm, 330–360 nm are important variables for discriminating four growth ages of P. kingianum. The classification effect of data fusion models was better than that of single spectra models with 100% accuracy as well as perfect sensitivity and specificity. Hierarchical cluster analysis shown that the samples were divided into two categories: one 5-year-old and the other 2, 3 and 4-year-old. In summary, the polysaccharide content in 4-year-old P. kingianum by seed reproduction was the highest. Data fusion of ATR-FTIR and UV-Vis spectra combined with PLS-DA models could be used to accurately distinguish P. kingianum in different growth ages, which was valuable for the identification and evaluation of other medicinal and edible homologous plants. Meanwhile, it also provides a theoretical basis for the harvesting age and cultivation conditions of P. kingianum.

Purpose To evaluate the impacts of different leaf-width of multileaf collimator (MLC) on the fixed-beam intensity-modulated radiotherapy (IMRT) planning for prostate cancer patients with intermediate risk factors. Materials and methods Sixteen prostate cancer patients with intermediate risk factors were retrospectively recruited. For each patient, the two IMRT plans using MLC leaf width of 10 mm and 4 mm (sIMRT and mIMRT) were compared. All of plans were generated with the same setup and optimized parameters and methods. Homogeneity index (HI), conformity index (CI), dose distribution for planning tumor volume (PTV) and organs at risk (OARs) were analyzed to evaluate the quality of the plans. Delivery time (DT), monitor units (MUs) and control points (CPs) were used to assess the efficiency of treatment. Results For the target dose distribution, the mean HI values of the two plans for 16 patients are similar (sIMRT vs. mIMRT: 1.120±0.13 vs. 1.103±0.099, p>0.05). The mean CI of the mIMRT plans was significantly better than that of the sIMRT plans (sIMRT vs. mIMRT: 0.648±0.11 vs. 0.688±0.10, p Conclusions For the IMRT of the prostate cancer patients with intermediate risk factors, the plans with the narrower leaf-width MLC failed to promote the quality of plans, OARs dose sparing and the efficiency of treatment, and could only improve the conformity of the plans.

Artemisia annua L., a famous traditional Chinese medicine, has been used as an antimalarial herbal medicine for thousands of years. Artemisinin, main bioactive constituent of A. annua L., is the principal contributor to its pharmacological effects. Previous studies have shown that A. annua L. of different germplasm has different morphological characteristics, herb yield, and artemisinin content. We propose a hypothesis that the morphological characteristic of A. annua L. may contribute to breeding new cultivars with high yield and high artemisinin content. To test this hypothesis, 8 morphological characteristics (plant height, stem bottom diameter, crown diameter, distance of internode, the number of primary branches, primary branch angle, leaf length, and leaf width) of A. annua L. from 64 germplasm resources were studied. The correlations between morphological characteristics and herb yield, artemisinin content were studied by using partial least squares regression (PLSR) analysis, correlation analysis, and path analysis. The results indicated that: (1) the same characteristic of different germplasm resources varied greatly under the same cultivation and management condition; (2) both the artemisinin content and herb yield were positively correlated to plant height, stem bottom diameter, crown diameter, distance of internode, leaf width, and negatively correlated to the number of primary branches. Nevertheless, the coefficients of correlation are very low and vary between r = 0.25 to r = 0.46; (3) the strongest relations were found for plant height and stem bottom diameters. In conclusion, both plant height and stem bottom diameter had the most important positive influence on artemisinin content of the leaves and herb yield. The results of the present study can help to increase breeding efficiency for getting new A. annua L. cultivars with high herbal yield and high artemisinin content.

Domestication of Prunus divaricata Ledeb. offers considerable scope for enhancing the nutritional and economic security of farmers. In the present study, phenotypic and pomological variability among 73 accessions of this species selected from eight natural habitats in the northern parts of Iran was investigated. The majority of traits measured showed significant variations among the investigated accessions. Leaf length ranged from 21.91 to 68.47 mm and leaf width varied from 8.17 to 36.39 mm. Fruit length varied from 11.48 to 28.01 mm and fruit weight ranged from 1.79 to 14.09 g with an average of 4.46. Fruit skin color was highly diverse so that 11 types of color were observed among the accessions ranging from yellowish-green to black. Fruit weight showed positive and significant correlations with leaf and fruit dimensions. Principal component analysis (PCA) extracted 10 components with explaining 74.52% of total variance and showed that the most important variables in distinguishing accessions were fruit size-related traits. The dendrogram obtained based on all the characters measured clustered the accessions into two major clusters. A high level of morphological and pomological variabilities was observed among the accessions, which is applicable and useful for plum breeding programs. The conclusion of the current investigation confirmed the necessity of preserving this irreplaceable genetic resource in its natural habitats in the north of Iran as well as ex-situ in germplasm collections. Finally, the investigated P. divaricata germplasm included some accessions that possessed valuable morphological and pomological traits which could be of special interest in marketing.

This study was aimed to obtain information of heritability predictive value and correlations of vegetative and generative characters on six genotypes of J. curcas . The characters of plant height, leaf number, leaf width, number of primary and secondary branches, number of fruit bunches, number of fruits per plant, seed's and 100 seeds’ dry weight showed high predictive value of heritability. Characters related to positive correlation and high heritability values (leaf width, number of primary branches, number of secondary branches, number of fruit bunches, number of fruits per plant) are able to be used as criteria for selection of J. curcas plant.

Three domesticated species of Cerasus L. subgenus including sweet cherry (Prunus avium L.), sour cherry (P. cerasus L.) and duke cherry (P. × gondouinii Rehd.) are interesting and increasingly important fruit species in the world. In the current study, morphological and pomological variability of 146 cherry accessions including 45 sweet cherries, 62 sour cherries, and 39 duke cherries was evaluated to select superior selections. Analysis of variance indicated that most of the studied accessions showed high variability for most of the traits. Fruit length ranged from 18.88 to 28.45 mm in sweet cherries, while it was varied from 11.17 to 14.64 mm in sour cherries and 15.37 to 18.60 mm in duke cherries. In addition, fruit weight varied from 4.40 to 8.86 g in sweet cherries, 1.36 to 2.67 g in sour cherries, and 4.40 to 6.04 g in duke cherries. Fruit weight showed positive and significant correlations with leaf length (r = 0.91), leaf width (r = 0.84), and leaf density (r = 0.40). The dendrogram generated using morphological data indicated two different clusters and separated the accessions based on their species. Based on the results obtained here, 20 sweet cherry, 13 sour cherry, and 12 duke cherry accessions can be recommended for cultivation. Furthermore, most of the accessions could substantially contribute to existent cherry breeding programs. The conservation of these autochthonous accessions is highly recommended.

The Varian Halcyon linear accelerator is designed for faster treatment time and fewer treatment errors than conventional linear accelerators. Its increased gantry speed (4 rpm), dose rate (800 MU/min), and leaf speed (5 cm/s) reduce treatment time. The 2 multileaf collimator banks of 1 cm leaf width could cause planning difficulties, but utilizing many arcs could address this challenge. While 3 or more arcs are often avoided due to the increased treatment time, the Halcyon can deliver 5 arcs in under 3 minutes. For prostate and head-and-neck, we hypothesized plan quality would increase with increasing arcs without compromising treatment time. Fifteen prostate and fifteen head-and-neck previously treated patients were replanned to 78 and 66 Gy, respectively. A total of 150 volumetric modulated arc therapy (VMAT) plans, ranging from 1 to 5 arcs, were created to compare organ-at-risk (OAR) sparing, target coverage, homogeneity, and hotspot volume. Plans were normalized to the prescribed dose of 98% and 95% of the primary target volume for prostate and head-and-neck, respectively. All prostate 4-arc and 5-arc plans met MD Anderson Cancer Center (MDACC) constraints, while 86.7%, 20%, and 6.7% of the 1-arc, 2-arc, and 3-arc plans did not meet constraints, respectively. As the number of arcs increased, all OAR maximum doses decreased. All head-and-neck 5-arc plans met MDACC constraints, while 73.3%, 26.7%, 13.3%, and 6.7% of the 1-arc, 2-arc, 3-arc, and 4-arc plans did not meet constraints, respectively. The contralateral parotid mean dose and the spinal cord maximum dose decreased with increasing arcs. Homogeneity and conformity indices decreased when increasing from 1 to 5 arcs for both prostate and head-and-neck. Overall, homogeneity and conformity indices and OAR doses improved when using three or more arcs. Therefore, using at least 3 arcs for VMAT plans on the Halcyon will increase plan quality without compromising treatment time.

Partial-breast irradiation (PBI) aims to limit the target volume for radiotherapy in women with early breast cancer after partial mastectomy to the region at highest risk of local recurrence, the tumor bed. Multileaf collimators are used to achieve conformal radiation beam portals required for PBI. Narrower leaf widths are generally assumed to allow more conformal shaping of beam portals around irregularly shaped target volumes. The aim was to compare 5-mm and 10-mm leaf widths for patients previously treated using PBI and assess subsequent planning target volume (PTV) coverage and organ at risk (OAR) doses for 16 patients. Several plans (5-mm leaf width or 10-mm leaf width) were generated for each patient using the original treated plan as the basis for attempts at further optimization. Alternating between different leaf widths found no significant difference in terms of overall PTV coverage and OAR doses between treatment plans. Optimization of the original treated plan allowed a small decrease in ipsilateral breast dose, which was offset by a lower PTV minimum. No significant dosimetric difference was found to support an advantage of 5-mm over 10-mm leaf width in this setting.

We report the production of an intergeneric hybrid between Dendranthema nankingense and Tanacetum vulgare via ovule rescue. Out of 420 cultured ovules, four gave rise to a total of 27 plantlets. A genomic in situ hybridization analysis confirmed that regenerated plantlets were all genuine hybrids. The leaf length, petiole length, number of tubular florets and epidermal hair density of the hybrids were all intermediate between those of the two parents. However, both the leaf width and epidermal hair length of the hybrids were less than those of the parents. The number of ligulate florets is significantly greater than those of the parents. Flower diameter and epidermal hair height is similar to that of paternal parent. GISH was able to distinguish the parental genomes in the hybrids, suggested the two genera is taxonomically distant from each other.

Croton Codiaeum variegatum (L.) Blume is a popular ornamental foliage plant that displays an anomalous range of variations in its leaf size, shape and color pattern. By fixing such leaf variations, more than 300 cultivars have been produced in the world. Until now, however, only a limited number of studies have been made to describe the leaf phenotypic diversity. Here we investigated the diversity of leaf phenotype in croton cultivars with a numerical taxonomic approach. One-way analysis of variance confirmed significant phenotypic variations in the croton cultivars for 12 quantitative leaf parameters. Among the numerical parameter tested, the leaf index that is the ratio of leaf length to leaf width showed the highest variability. High coefficient of variation values were observed in petiole length, leaf area and leaf down quarter width. In contrast with leaf morphology, the composition of leaf pigments that contribute to leaf coloration did not show diversity. Based on the analyses of the leaf parameters, we clustered the croton cultivars into four major groups. The results of this study provide a numerical basis for classification of croton cultivars. A possible involvement of transposon is discussed in terms of somatic mutation that results in the leaf phenotypic diversity.

Mathematical models based on dynamic growth process of greenhouse melon leaves were built. Two experiments, involving different years, organic fertilizer rates and cultivar types in melon, were carried out for data acquisition. In each experiment, time-course observations of leaf morphological properties (leaf length and leaf width) on different leaf positions of melon were obtained. The results showed that the logistic mathematical models were suitable to simulate the dynamic elongation of leaf length and leaf width with the dynamic changes of @?TU (accumulated thermal units), logarithmic equation and quadratic curve equation fit the dynamic changes of the final leaf length and the maximum leaf width with different leaf positions well, and the leaf area dynamic changes were simulated by binary regression equation. In addition, the effects of nitrogen conditions on leaf growth were quantified by the effectiveness values of nitrogen concentration in leaves. The model was validated with independent field experiment data, and the results showed that the mean RMSE (root mean square error) of leaf length, leaf width and leaf area under different @?TU was 0.54 cm, 1.19 cm, 0.44 cm^2, respectively.

We compared the impacts of multileaf collimator (MLC) widths (standard MLC width of 10 mm [SMLC] and micro-MLC width of 4 mm [MMLC]) on intensity-modulated radiotherapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Ten patients with NPC were recruited in this study. In each patient's case, plans were generated with the same machine setup parameter and optimizing methods in a treatment planning system according to 2 commercial Elekta MLC devices. All of the parameters were collected from dose-volume histograms of paired plans and evaluated. The average conformity index (CI) and homogeneous index (HI) for the planning gross target volume in IMRT plans with MMLC were 0.790 ± 0.036 and 1.062 ± 0.011, respectively. Data in plans with SMLC were 0.754 ± 0.038 and 1.070 ± 0.010, respectively. The differences were statistically significant (p < 0.05). Compared with CI and HI for planning target volume in paired plans, data with MMLC obviously were better than those with SMLC (CI: 0.858 ± 0.026 vs. 0.850 ± 0.021, p < 0.05; and HI: 1.185 ± 0.011 vs. 1.195 ± 0.011, p < 0.05). However, there was no statistical significance between evaluated parameters (Dmean, Dmax, D5, gEUD, or NTCP) for organs at risk (OARs) in the 2 paired IMRT plans. According to these two kinds of Elekta MLC devices, IMRT plans with the MMLC have significant advantages in dose coverage for the targets, with more efficiency in treatment for NPC but fail to improve dose sparing of the OARs.

Four Taiwanese native Miscanthus floridulus lines, collected at altitudes of 260, 500, 1000, and 1500 m were cultivated in 2009 and 2010. The plant height and tiller numbers of four M . floridulus lines increased gradually along with the growing time. These M. floridulus lines had the tallest plant height and most tiller number after these species were planted 210 days. Line 3, which was collected at the altitude of 1000 m, had the ability to grow at low temperature. Line 3 M . floridulus had the highest plant height, tiller number, fresh and dry yields than other three lines. Fresh and dry yields of Line 3 were positively correlated to the plant height, tiller number, and leaf width, but showed no correlation with the leaf length. The correlation between agronomic traits and climatic data was also studied. Results can be used as a model for developing a non-food crop-based energy production system in the future.

Rapid expansion of leaves of early-stage plants in wheat produced by chromosomal control of characteristics related to rapid expansion of the first six leaves of wheat were investigated using a set of single chromosome substitution lines under two different temperature regimes (TRs). Results from this study indicated that several chromosomes could be responsible for each of the four characteristics studied (including leaf width, leaf length, leaf elongation rate and leaf appearance index) and that different chromosomes may be responsible for the same characteristics at different TRs. Only a small number of substitutions that showed the most significant effects on leaf length were found among those that showed the most significant effects on leaf width, providing further evidence that these two characteristics are likely controlled by different sets of genes. Substitutions 4B, 4D, and 5A are among those that were repeatedly detected to having significant effects on different leaf characteristics at the lower-TR and genes residing on these three chromosomes could be homologous. This possibility and its implication are discussed.

We studied the effect of MLC (multileaf collimator) leaf width and PTV (planning target volume) margin on treatment planning of intensity modulated stereotactic radiosurgery (IMSRS) or radiotherapy (IMSRT). Twelve patients previously treated with IMSRS/IMSRT were retrospectively planned with 5- and 3-mm MLC leaf widths and 3- and 2-mm PTV margins using the already contoured clinical target volume and critical structures. The same beam arrangement, planning parameters, and optimization method were used in each of the 4 plans for a given patient. Each plan was normalized so that the prescription dose covered at least 99% of the PTV. Plan indices--D(mean) (mean dose), conformity index (CI), V(70) (volume receiving >or= 70% of the prescription dose), and V(50) (volume receiving >or= 50% of the prescription dose)--were calculated from the dose-volume histograms (DVHs) of the PTV, normal tissue, and organs at risk (OARs). Hypothesis testing was performed on the mean ratios of plan indices to determine the statistical significance of the relative differences. The PTV was well covered for all plans, as no significant differences were observed for D(95), V(95), D(max), D(min), and D(mean) of the PTV. The irradiated volume was approximately 23% smaller when 2-mm instead of 3-mm PTV margin was used, but it was only reduced by approximately 6% when the MLC leaf width was reduced from 5 mm to 3 mm. For normal tissue and brainstem, V(70), V(50), and D(mean) were reduced more effectively by a decrease in MLC width, while D(mean) of optic nerve and chiasm were more sensitive to a change in PTV margin. The DVH statistics for the PTV and normal structures from the treatment plan with 5-mm MLC and 2-mm PTV margin were equal to those with 3-mm MLC and 3-mm PTV margin. PTV margin reduction is more effective in sparing the normal tissue and OARs than a reduction in MLC leaf width. For IMSRS, where highly accurate setup and small PTV margins are routinely employed, the use of 5-mm MLC is therefore less desirable.

We investigated the differences between 3-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT), and the impact of collimator leaf-width on IMRT plans for the treatment of nonspherical brain tumors. Eight patients treated by 3DCRT with Novalis were selected. We developed 3 IMRT plans with different multileaf collimators (Novalis m3, Varian MLC-120, and Varian MLC-80) with the same treatment margins, number of beams, and gantry positions as in the 3DCRT treatment plans. Treatment planning utilized the BrainLAB treatment planning system. For each patient, the dose constraints and optimization parameters remained identical for all plans. The heterogeneity index, the percentage target coverage, critical structures, and normal tissue volumes receiving 50% of the prescription dose were calculated to compare the dosimetric difference. Equivalent uniform dose (EUD) and tumor control probability (TCP) were also introduced to evaluate the radiobiological effect for different plans. We found that IMRT significantly improved the target dose homogeneity compared to the 3DCRT. However, IMRT showed the same radiobiological effect as 3DCRT. For the brain tumors adjacent to (or partially overlapping with) critical structures, IMRT dramatically spared the volume of the critical structures to be irradiated. In IMRT plans, the smaller collimator leaf width could reduce the volume of critical structures irradiated to the 50% level for those partially overlapping with the brain tumors. For relatively large and spherical brain tumors, the smaller collimator leaf widths give no significant benefit.

Non-destructive and mathematical approaches of modeling can be very convenient and useful for plant growth estimation. To predict individual leaf area, fresh weight, and dry weight of a cucumber ( Cucumis sativus L.), models were developed using leaf length, leaf width, SPAD value, and different combinations of these variables. Eight regression equations, commonly used for developing growth models, were compared for accuracy and adaptability. The three nonlinear models developed were as follows: individual leaf area (LA) = −210.61 + 13.358 W + 0.5356 LW ( R 2 = 0.980 *** ), fresh weight (FW) = −2.72 + 0.0135 LW + 0.00022 LWS ( R 2 = 0.956 *** ), and dry weight (DW) = 0.25 − 0.00102 LS + 0.000077 LWS ( R 2 = 0.956 *** ), where L is the leaf length, W the leaf width, S the SPAD value, and LWS = L × W × S . For validation of the model, estimated values for individual leaf area, fresh weight, and dry weight showed strong agreement with the measured values, respectively. Leaf dry weight, especially, was estimated with a higher degree of accuracy through the use of a SPAD value, as well as leaf length and width. Therefore, it is concluded that models presented herein may be useful for the estimation of the individual leaf area, fresh weight, and dry weight of a cucumber with a high degree of accuracy.

There were two peach descriptors systems: one from IPRGI in 1980 and the other from China in 1990. The former had only reference cultivars without quantity grades; the latter had only a list of some characteristics. This makes it difficult sharing of genetic resource information for breeders. To describe the main quantitative characteristics, a new system was established. Ten characteristics of 346-476 peach cultivars were investigated from 1986 to 2002 in the National Peach Genetic Collection in Zhengzhou City, China. These characteristics and their coefficients of variation were as follows: flower diameter 19.55%, vertical diameter of fruit 14.24%, cheek diameter of fruit 10.36%, suture diameter of fruit 11.44%, stone length 19.04%, stone width 10.86%, stone thickness 11.19%, leaf length 7.9%, leaf width 10.55%, and leaf stalk length 19.03%, respectively. Grade index and reference cultivars were given by statistical data for peach description. These grade indexes were recorded on 1-5 grades, and the third grade as a middle one occupied 39% or more of the distribution. In general, two reference cultivars for each grade were chosen, one is USA cultivar and the other is Chinese cultivar. This paper tried to use them as the reference cultivars, which are planted or used widely by Chinese breeders.

Purpose: To perform a dosimetric comparison of a minimal 3-mm leaf width multileaf collimator (MLC) and a minimal 5-mm MLC in dynamic conformal arc stereotactic radiosurgery for treatment of intracranial lesions. Methods and Materials: The treatment plans of 23 patients previously treated for intracranial lesions in our institution were redone using the BrainSCAN, version 5.3, stereotactic radiosurgery treatment planning system (BrainLAB). For each case, two dynamic conformal arc plans were generated: one using a minimal 3-mm micro-MLC (BrainLAB, Novalis) and one using a minimal 5-mm MLC (Varian Millennium). All arc parameters were the same in each of the two plans, except for the collimator angle settings. The collimator angle settings were optimized for each arc in each plan. A peritumoral rind structure (1 cm) was created to evaluate normal tissue sparing immediately adjacent to the target volume. Conformity indexes (CIs) were calculated for each plan. The dependence of normal tissue sparing and target conformity on target volume (TV) was determined. Results: The TV was 0.14–36.32 cm 3 (median, 5.90). The CI was 1.22–2.60 (median, 1.51) for the 3-mm micro-MLC and 1.23–2.69 (median, 1.60) for the 5-mm MLC. Despite this small difference, it was a statistically significant increase ( p 50 ), 80% (PRV 80 ), and 90% (PRV 90 ) of the prescription dose. The reduction in the PRV 50 , PRV 80 , and PRV 90 for the 3-mm micro-MLC compared with the 5-mm MLC was 13.5%, 12.9%, and 11.5%, respectively. The CI decreased with a larger TV, as did the difference in the CIs between the 3-mm micro-MLC and 5-mm MLC. A reduction in the PRV increased with larger TVs. Conclusion: The 3-mm micro-MLC provided better target conformity and greater normal tissue sparing than the 5-mm MLC in stereotactic radiosurgery using dynamic conformal arcs. These differences were small but consistent in the patients examined. Future research is needed to determine whether this small improvement can yield a clinical impact on patient care.

Purpose: This study compares the width of the penumbra obtained from two small-leaf multileaf collimators (MLCs) recommended for use in small field shaping for such techniques as stereotactic radiosurgery. Methods and Materials: High-resolution film dosimetry measurements were taken to characterize two MLCs with 3-mm and 5-mm leaf width at isocenter. The differences observed between leaf tip and leaf edge penumbra measured between 80% and 20% of maximum were explained using a simple model calculating transmission through the leaf tip geometry. Results: Substantial differences were found between the 80% to 20% penumbra for the two MLCs. The 3-mm MLC designed for a maximum field size of 9.8 cm × 9.8 cm showed 80% to 20% penumbra values of 2.4 ± 0.1 mm in both the directions perpendicular and parallel to the leaf motion. The 5-mm MLC designed for field sizes up to 40 cm × 40 cm showed comparable 80% to 20% penumbra in the direction perpendicular to leaf motion and 3.2 ± 0.1 mm in the direction parallel to leaf motion. The transmission modeling illustrated that this difference is largely due to the curvature of the leaf tip. It was found that to accommodate larger field sizes the leaf tip must have greater curvature, resulting in a larger penumbra. Conclusions: The results of this study show a difference in the leaf penumbra parallel to the direction of leaf motion between two MLCs designed for precision radiation therapy. This difference may be attributed to the leaf tip design and is determined by the maximum field size of the MLC. This difference is currently not modeled by all treatment planning systems and should be taken into account as part of any procurement assessment of a system for precision radiation therapy in the same way that the width of the leaf at isocenter would be considered.

For population viability analysis of endangered orchid populations, it is crucial to disentangle the effects of weather and management from intrinsic orchid dynamics. When doing this, typically several months’ average temperatures and/or sums of precipitations are compared with some characteristics of plant performance. Here we tested, whether short averaging intervals (1–2 weeks) are more closely correlated with orchid performance. We used 5 years of data from five Dactylorhiza majalis populations, and have shown that the improvement of prediction by shortening the interval over which the temperatures are averaged or precipitation summed, even if detectable, is only weak and not significant. This, however, may be due to low weather variability during the study. Regarding the second aspect, the effect of management (presence or absence of mowing), we have found that leaf area of D. majalis at the regularly mown site was larger than that at the sites which were mown only once in 2 years, but we did not detect a significant effect of the absence of mowing on the incidence of flowering. Mowing can affect orchid performance in two ways: by reduced shading of orchids and by reducing competition with other species. Therefore, we have determined the co-occurring species associated with presence or absence of mowing and found that shading significantly affected the length of the flower stalk, the ratio of leaf width to leaf length at the end of the season, but did not affect seed weight and probability of flowering the next year. We conclude that the most appropriate management for D. majalis is mowing at least once a year, ideally at the end of June/beginning of July, after its fruiting.

WOS: 000236454100018 In this research, an equation for estimating the leaf area was derived for the chestnut tree by using 18 chestnut genotypes and by measuring the lamina width, length and leaf area without damage being caused in 2004-2005. Multiple regression analysis for the genotypes was separately performed. The proposed leaf area (LA) estimation model is: LA = 3.36 + 0.11 L-2 - 0.26 L-2/W-2 + 1.1 W-2, R-2 = 0.988, where LA is the leaf area, W is the leaf width and L is the leaf length. The model was validated by measuring leaf samples of the SE-21-2 genotype in different climate conditions in 2004-2005. (c) 2006 Elsevier B.V. All rights reserved.

Purpose The influence of the multileaf collimator (MLC) leaf width on the dose distribution in patients treated with conformal radiotherapy and intensity-modulated radiotherapy has been analyzed. This study was based on the Monte Carlo simulation with the beams generated by a linac with the double-focused MLC. Materials and methods The transmission through the leaves and the exact shape of the penumbra regions are difficult to model by treatment planning system algorithms. An accurate assessment of the dose variations due to the leaf width change can be achieved by means of Monte Carlo simulation. The BEAM/EGS4 code was used at the Hospital of the Virgen Macarena to model a Siemens PRIMUS linac, featuring an MLC with a leaf width projecting 1 cm at the isocenter. Based on this real model, a virtual head was designed while allowing for a variation of the leaf width projection. Both the real linac and the virtual linac, with leaves projecting 0.5 cm, were used to obtain the dose distributions for several treatments. A few disease sites, including the prostate, head and neck, and endometrium, were selected for the design of the conformal and intensity-modulated radiotherapy treatments with a forward planning algorithm sensitive to the different shapes of the volumes of interest. Isodose curves, differential matrix, gamma function, and the dose–volume histograms (DVHs) corresponding to both MLC models were obtained for all cases. The tumor control probability and the normal tissue complication probability were derived for those cases studied featuring the greatest differences between results for both MLCs. Results The impact on the DVHs of changing leaf width projections at the isocenter from 1.0 cm to 0.5 cm was low. Radiobiologic models showed slightly better tumor control probability/normal tissue complication probability values using the virtual MLC with a leaf width projecting 0.5 cm at isocenter in those cases presenting greater differences in the DVHs. Conclusions The impact on the clinical dose distribution due to the MLC leaf width change is low based on the design and conditions used in this study.

Purpose/objective: Stereotactic radiosurgery of brain metastases requires highly conformal dose distributions. Besides beams setup, characteristics of the linear accelerator collimator may also play a role. In this study we compared the impact of leaf width on the dose outside the target for stereotactic radiosurgery of single brain metastases. Results: The mean dose was evaluated in the first 2 rings of 5 mm around the PTV(table 1). The difference in mean dose for the small lesions(Dpres=24 Gy) of the first ring of 5 mm is 1.8 Gy in favor of the Agility and 0.9 Gy for the larger lesions(Dpres=18 Gy)also in favor of the Agility. The difference is smaller for the larger lesions (figure1). Also for the second ring of 5 mm, adjacent to the first ring, the difference is is 1.1 Gy vs 0.8 Gy also in favor of the Agility. Conclusion: For the small lesions with a volume smaller than 4 cm³ the Agility shows a steeper gradient in the two surrounding rings than the MLCi1. Therefore we recommend the use of the Agility for treating the smaller lesions.

Leaves were sampled from Vitis labruscana Bailey cv. ‘Niagara’ and the interspecific hybrid ‘DeChaunac’ grapevines several times during a 2-year investigation of leaf area estimation. Linear measurements of leaf length and width were made and correlated with leaf area measurements made with a computerized image processing system. For each cultivar, nine regression equations were derived and compared. Most models resulted in high (R2=0.90) coefficients of determination, but the power model using leaf width provided a high R2 and relatively low standard error of the estimate (‘Niagara’: area=0.637W1.995, R2=0.9821, and S.E.=10.58; ‘DeChaunac’: area=0.672W1.963, R2=0.9632, S.E.=5.67). Use of single-variable equations facilitates simple, rapid, and accurate estimation of ‘Niagara’ and ‘DeChaunac’ leaf area.

Accurate estimates of leaf area index (LAI) and leaf angle distribution (LAD) are important for estimating the exchange of energy and gases in vegetative canopies. Direct estimates of LAI and LAD are laborious, time consuming and often times destructive. Stewart and Dwyer [Agric. For. Meteorol. 66 (1993) 247] introduced a mathematical method to calculate LAI and LAD of maize canopies based on descriptions of leaf width and leaf curvature. However, the method is limited in its application. The objectives of this research are to: (1) extend the method to account for leaves with maximum curvature height at the leaf tip (i.e., straight leaves, which commonly occurs with leaves at the top of maize canopies), so that the method provides a general application to maize canopies, and (2) test the performance of the extended model. LAI and LAD simulated using the mathematical method were tested against observed LAI and LAD values. Average leaf width coefficients, determined from all leaf positions, were used in the leaf area calculation. Leaf area simulations agreed overall within 2% (51 cm2) of observed leaf area values. Estimated LAD agreed within 5% of the field observed LAD. The method offers a straightforward, reliable means of estimating LAI and LAD, when the appropriate coefficients are known, without requirements for special instrumentation or other conditions. The method also offers a means of checking the performance or reliability of other methods of characterizing canopy structure.

Growth rates of Halodule wrightii determined using the traditional method of clipping and reharvesting were compared to those determined using the hole-punching method in four populations distributed in coastal lagoons of the Yucatan Peninsula, Mexico. For three of the four populations, clipped shoots revealed 38–56% lower growth rates than punched shoots. The decrease in leaf production per shoot and on an areal basis in clipped shoots compared to punched shoots resulted from generally lower new leaf length, and, of equal or greater importance, leaf width of these shoots. Thus, the clip and reharvest method for assessing H. wrightii leaf production yielded underestimates. Leaf-punching is a convenient method in populations characterized by relatively broad leaves, such as those in Yucatan lagoons. From these populations, the highest published values for leaf elongation rates of H. wrightii to date (11.7–20.6 mm shoot−1 d−1) and summer areal production rates of 4.2–5.8 g dw m−2 d−1. Long-term production data for this species are crucial for managing subtropical coastal environments. Because contrasting methods have been employed to estimate the growth of H. wrightii, spatial and temporal comparisons of production from published reports are difficult to make, and a unified robust method for estimating growth rates and areal production of this seagrass is needed.

Background and purpose: There is concern over the stepped edges of multileaf collimator (MLC) fields for target coverage compared with those of cerrobend. Despite recent reports dispelling this concern, users are still cautious when using MLCs for small fields. Leaf orientation can be a problem if one is required to orient the leaves along an axis not ideal for conformity (such as dynamic or universal wedge cases). In this study we examined the dependence of MLC field conformity on field size and elongation. Materials and methods: We examined circles of varying diameter and ellipses of varying eccentricity with leaves oriented along the major and minor axes of ellipses. The tests were both geometric, comparing areas of overblocking or underblocking (leaves inside and outside the field), and dosimetric, using radiographic films at depth in the beam's eye view plane. Results: For the geometric comparison there is a rapid increase in non-conformity, defined as the percentage of overblocking or underblocking area, as the circle diameter decreases. For ellipses, when the leaves move along one axis direction, the conformity does not depend on the diameter of the same axis, but instead improves as the dimension of the axis in the non-leaf motion direction increases. The best conformity is achieved when the maximum number of leaves is used to shape the field. When the dosimetry is analyzed, the predictability of these trends decreases due to the impact of undulations (scatter), leaf inaccuracies and dosimetric uncertainties. Conclusions: We recommend that for small round fields MLC should be used with caution and that for ellipses the direction of leaf movement should be aligned with the minor axis whenever possible. Though these experiments are for idealized geometries, the observations can be applied to clinical fields. An MLC with a thinner leaf width could be beneficial for small round fields.

In Rio de Janeiro state the seagrass Halodule wrightii Aschers. is reaching its southernmost limit, and populations are small, isolated and infrequently sexually reproductive. Leaf width and length, number of leaves short shoot −1 , leaf sheath length, rhizome width, internode length, and root length and density were measured in 9 populations, and on three occasions within a single population. Each population featured at least one morphological attribute which differed from others. Leaf lengths varied 11-fold between populations, and each morphological feature was site dependent, but widths of leaves, diameters of rhizomes and the number of leaves per short shoot were the least, and root density the most variable features. Variation in a population over time was similar in scale to variation between plants, though leaf number varied very little over time. Leaf widths, lengths, sheath lengths, rhizome diameters and root densities showed more variation between than within populations. The variation in some characteristics within a single population was as high or higher than that reported within or between species of seagrasses. One population was polymorphic. The high degree of variation was consistent with the hypothesis of genetically mediated morphological differences between populations.

Thalassia testudinum Banks ex Konig in a Mexican Caribbean reef lagoon showed considerable differences in leaf length and width between three sampling stations. A reciprocal transplantation experiment between these stations was completed in July 1991. After one and a half years of observation, no significant differences in leaf length were recorded among the transplants from different origins. Although differences in leaf width diminished between the transplants from different origins, leaf width showed less plasticity than leaf length, and at one station, significant small differences were still evident after 2 years.

Hotspot is a prominent feature of the reflectance distribution of a vegetation canopy consisting of finite size foliage. It depends on the geometric dimension and spatial organization of vegetation elements, and therefore has a potential for diagnosing canopy geometric structure. In the context of this study, we first reconcile different notations used by previous workers. This leads to geometrically quantifying the cross-correlation function, which is essential for the hotspot modeling. A comprehensive formulation for the hotspot effect at both leaf and canopy levels is then developed, by generally parameterizing some basic parameters such as mean area of shadows and overlap between shadows cast by scatterers. A rectangle model is proposed to account for the influence of noncircular shape of scatterers on the hotspot effect, and explicit expressions for both the cross-correlation function and the hotspot width are obtained. It is shown that for a leaflike object, the angular hotspot width progressively broadens with an increase of m, the ratio of mean leaf width to the length. For the whole canopy, the relative distribution of the hotspot intensity mainly depends on this ratio. That is, the cross-correlation function decreases more rapidly for smaller m as the viewing direction diverges from the illumination direction. As a result, canopy reflectance increases with m, particularly in the region around the hotspot point where the reflectance distribution strongly relies on the ratio m. For m = π / 4 , the rectangle model produces nearly same result as the disk model. This indicates this rectangle model is more realistic and flexible than those based on circle-shaped scatterers (leaves) or their shadows, which is the common assumption underlying in most existing hotspot models.

Incident light available to a meadow of the seagrass Posidonia sinuosa Cambridge and Kuo in Princess Royal Harbour, Western Australia, was reduced by 80–99% for 148 days using shadecloth, starting in summer. Shading reduced the density of leaf-bearing shoots, leaf density, primary productivity and the leaf production per shoot. Leaf width was unaffected by shading. Recovery of the seagrass meadow was assessed from differences in the above variables among controls and treatments, measured on separate occasions over 245 days after removal of the shadecloth. Leaf production per shoot and leaf length of active shoots recovered rapidly after shading while shoot densities did not, being significantly lower than controls at the end of the study. Longer periods of shading produced greater reductions in shoot density and productivity. By the end of the study, shoot density and productivity of seagrasses shaded for 307 days were each about one-tenth that of unshaded seagrasses while productivity of seagrasses shaded for 393 days was less than 8% that of unshaded seagrasses. Such responses suggest that reduction in incident light at the levels used in this study would lead to collapse of the seagrass meadow within 2 years.