RING/U-box E3 protein BIR1 interacts with and ubiquitinates barley growth repressor BROAD LEAF1.

Establishment of final leaf size in plants relies on the precise regulation of two interconnected processes, cell division and cell expansion. The barley (Hordeum vulgare) protein BROAD LEAF1 (BLF1) limits cell proliferation and leaf growth in the width direction. However, how the levels of this potent repressor of leaf growth are controlled remains unclear. Here we used a yeast two-hybrid screen to identify the BLF1-INTERACTING RING/U-BOX 1 (BIR1) E3 ubiquitin ligase that interacts with BLF1 and confirmed the interaction of the two proteins in planta. Inhibiting the proteasome caused overaccumulation of a BLF1-eGFP fusion protein when co-expressed with BIR1, and an in vivo ubiquitination assay in bacteria confirmed that BIR1 can mediate ubiquitination of BLF1 protein. Consistent with regulation of endogenous BLF1 in barley by proteasomal degradation, inhibition of the proteasome in BLF1-vYFP-expressing barley plants caused an accumulation of the BLF1 protein. The BIR1 protein co-localized with BLF1 in nuclei and appeared to reduce BLF1 protein levels. Analysis of bir1-1 knock-out mutants suggested the involvement of BIR1 in leaf growth control, although mainly on leaf length. Together, our results suggest that proteasomal degradation, in part mediated by BIR1, helps fine-tune BLF1 protein levels in barley.

Comparison between computer recognition and manual measurement methods for the estimation of leaf area.

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

The gain-of-function mutation blf13 in the barley orthologue of the rice growth regulator NARROW LEAF1 is associated with increased leaf width.

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

NLG1, encoding a mitochondrial membrane protein, controls leaf and grain development in rice.

BACKGROUND: Mitochondrion is the key respiratory organ and participate in multiple anabolism and catabolism pathways in eukaryote. However, the underlying mechanism of how mitochondrial membrane proteins regulate leaf and grain development remains to be further elucidated. RESULTS: Here, a mitochondria-defective mutant narrow leaf and slender grain 1 (nlg1) was identified from an EMS-treated mutant population, which exhibits narrow leaves and slender grains. Moreover, nlg1 also presents abnormal mitochondria structure and was sensitive to the inhibitors of mitochondrial electron transport chain. Map-based cloning and transgenic functional confirmation revealed that NLG1 encodes a mitochondrial import inner membrane translocase containing a subunit Tim21. GUS staining assay and RT-qPCR suggested that NLG1 was mainly expressed in leaves and panicles. The expression level of respiratory function and auxin response related genes were significantly down-regulated in nlg1, which may be responsible for the declination of ATP production and auxin content. CONCLUSIONS: These results suggested that NLG1 plays an important role in the regulation of leaf and grain size development by maintaining mitochondrial homeostasis. Our finding provides a novel insight into the effects of mitochondria development on leaf and grain morphogenesis in rice.

Artificial neural network approach for predicting the sesame (Sesamum indicum L.) leaf area: A non-destructive and accurate method.

The estimative of the leaf area using a nondestructive method is paramount for successive evaluations in the same plant with precision and speed, not requiring high-cost equipment. Thus, the objective of this work was to construct models to estimate leaf area using artificial neural network models (ANN) and regression and to compare which model is the most effective model for predicting leaf area in sesame culture. A total of 11,000 leaves of four sesame cultivars were collected. Then, the length (L) and leaf width (W), and the actual leaf area (LA) were quantified. For the ANN model, the parameters of the length and width of the leaf were used as input variables of the network, with hidden layers and leaf area as the desired output parameter. For the linear regression models, leaf dimensions were considered independent variables, and the actual leaf area was the dependent variable. The criteria for choosing the best models were: the lowest root of the mean squared error (RMSE), mean absolute error (MAE), and absolute mean percentage error (MAPE), and higher coefficients of determination (R2). Among the linear regression models, the equation yˆ=0.515+0.584*LW was considered the most indicated to estimate the leaf area of the sesame. In modeling with ANNs, the best results were found for model 2-3-1, with two input variables (L and W), three hidden variables, and an output variable (LA). The ANN model was more accurate than the regression models, recording the lowest errors and higher R2 in the training phase (RMSE: 0.0040; MAE: 0.0027; MAPE: 0.0587; and R2: 0.9834) and in the test phase (RMSE: 0.0106; MAE: 0.0029; MAPE: 0.0611; and R2: 0.9828). Thus, the ANN method is the most indicated and accurate for predicting the leaf area of the sesame.

Identification of a Rice Leaf Width Gene Narrow Leaf 22 (NAL22) through Genome-Wide Association Study and Gene Editing Technology.

Rice leaf width (RLW) is a crucial determinant of photosynthetic area. Despite the discovery of several genes controlling RLW, the underlying genetic architecture remains unclear. In order to better understand RLW, this study conducted a genome-wide association study (GWAS) on 351 accessions from the rice diversity population II (RDP-II). The results revealed 12 loci associated with leaf width (LALW). In LALW4, we identified one gene, Narrow Leaf 22 (NAL22), whose polymorphisms and expression levels were associated with RLW variation. Knocking out this gene in Zhonghua11, using CRISPR/Cas9 gene editing technology, resulted in a short and narrow leaf phenotype. However, seed width remained unchanged. Additionally, we discovered that the vein width and expression levels of genes associated with cell division were suppressed in nal22 mutants. Gibberellin (GA) was also found to negatively regulate NAL22 expression and impact RLW. In summary, we dissected the genetic architecture of RLW and identified a gene, NAL22, which provides new loci for further RLW studies and a target gene for leaf shape design in modern rice breeding.

Planning issues on linac-based stereotactic radiotherapy.

This work aims to summarize and evaluate the current planning progress based on the linear accelerator in stereotactic radiotherapy (SRT). The specific techniques include 3-dimensional conformal radiotherapy, dynamic conformal arc therapy, intensity-modulated radiotherapy, and volumetric-modulated arc therapy (VMAT). They are all designed to deliver higher doses to the target volume while reducing damage to normal tissues; among them, VMAT shows better prospects for application. This paper reviews and summarizes several issues on the planning of SRT to provide a reference for clinical application.

Comparison of Leaf Shape between a Photinia Hybrid and One of Its Parents.

Leaf shape and size can vary between hybrids and their parents. However, this has seldom been quantitatively tested. Photinia × fraseri is an important landscaping plant in East Asia as a hybrid between evergreen shrubs P. glabra and P. serratifolia. Its leaf shape looks like that of P. serratifolia. To investigate leaf shape, we used a general equation for calculating the leaf area (A) of broad-leaved plants, which assumes a proportional relationship between A and product of lamina length (L) and width (W). The proportionality coefficient (which is referred to as the Montgomery parameter) serves as a quantitative indicator of leaf shape, because it reflects the proportion of leaf area A to the area of a rectangle with L and W as its side lengths. The ratio of L to W, and the ellipticalness index were also used to quantify the complexity of leaf shape for elliptical leaves. A total of >4000 leaves from P. × fraseri and P. serratifolia (with >2000 leaves for each taxon) collected on a monthly basis was used to examine: (i) whether there is a significant difference in leaf shape between the two taxa, and (ii) whether there is a monotonic or parabolic trend in leaf shape across leaf ages. There was a significant difference in leaf shape between the two taxa (p < 0.05). Although there were significant differences in leaf shape on a monthly basis, the variation in leaf shape over time was not large, i.e., leaf shape was relatively stable over time for both taxa. However, the leaf shape of the hybrid was significantly different from its parent P. serratifolia, which has wider and more elliptical leaves than the hybrid. This work demonstrates that variations in leaf shape resulting from hybridization can be rigorously quantified and compared among species and their hybrids. In addition, this work shows that leaf shape does not changes as a function of age either before or after the full expansion of the lamina.

Dosimetric sensitivity of leaf width on volumetric modulated arc therapy plan quality: an objective approach.

Background: Several authors investigated a dosimetric impact of leaf width on radiotherapy plan quality subjectively, and concluded that thinner leaf-width multileaf collimators (MLC) are beneficial because of their better coverage of clinically relevant structures. Study aimed to investigate the dosimetric effect of MLC leaf width on volumetric modulated arc therapy plan quality by objective approach. Materials and methods: Twelve of each prostate and head-and-neck patients were planned for volumetric modulated arc therapy (VMAT) treatments for MLC leaf widths of 4 mm and 10 mm. Three different VMAT schemes single-arc, dual-arc and two combined independent single-arcs were optimized. Dose volume histogram and Isodose distribution were used for quantitative and qualitative comparison of the treatment plan, respectively. Dose-volume-indices of the planning target volume, organs at risk and number of delivered monitor units were compared. The 4 mm leaf width being reference over 10 mm and results were noted as statistically significant if p ≤ 0.05 using student t-test. Results: All VMAT schemes for both tumor sites showed a gain in target coverage, similar organs at risk doses and higher monitor units to be delivered, when changing leaf width from 10 mm to 4 mm. The p-values were significant for majority of head-and-neck dose indices. Conclusion: The thinner-leaf MLCs, owing to their better spatial resolution, result in an overall gain for target coverage, while maintaining permissible doses to the organs at risk.

Effect of the simulated half leaf width of a multileaf collimator on volumetric modulated arc therapy plan quality in hippocampal avoidance whole-brain radiotherapy.

PURPOSE: Whole-brain radiotherapy (WBRT) is commonly used in patients with multiple brain metastases. Compared with conventional WBRT, hippocampal avoidance WBRT (HA-WBRT) more favorably preserves cognitive function and the quality of life. The hippocampal volume is considerably small (approximately 3.3 cm3 ). Therefore, downsizing the leaf width of a multileaf collimator (MLC) may provide higher spatial resolution and better plan quality. Volumetric modulated arc therapy (VMAT) could simulate the half MLC leaf width through couch shifting between arcs. This study investigated changes in VMAT quality for HA-WBRT with a simulated fine MLC leaf width. METHODS: We included 18 patients with brain metastasis. All target and avoidance structures were contoured by an experienced radiation oncologist. The prescribed dose was 30 Gy in 10 fractions. For each patient, three different treatment plans were generated for comparison: VMAT with couch-shift, VMAT without couch-shift, and TomoTherapy. All treatment plans fulfilled Radiation Therapy Oncology Group (RTOG) 0933 criteria for HA-WBRT. The Wilcoxon paired signed-rank test was used to compare different treatment plans. RESULTS: VMAT with couch-shift had the better average conformity index (0.823) with statistically significant difference compared to VMAT without couch-shift (0.810). VMAT with couch-shift (0.219) had a more favorable average homogeneity index (HI) than did VMAT without couch-shift (0.230), although the difference was not significant. TomoTherapy had an optimal average HI of 0.070. In terms of the hippocampus, all three treatment plans met the RTOG 0933 criteria. VMAT with couch-shift had a lower average Dmax (15.2 Gy) than did VMAT without couch-shift (15.3 Gy, p = 0.071) and TomoTherapy (15.5 Gy, p = 0.133). The average D100% of hippocampus was the same for both VMAT with and without couch-shift (8.5 Gy); however, TomoTherapy had a lower average D100% value of 7.9 Gy. The treatment delivery time was similar between VMAT with and without couch-shift (average, 375.0 and 369.6 s, respectively). TomoTherapy required a long average delivery time of 1489.9 s. CONCLUSION: The plan quality of VMAT for HA-WBRT was improved by using the couch-shift technique to simulate the half MLC leaf width. However, the improvement was not statistically significant except conformity index. The downsizing effect decreased with the use of the sophisticated grade of VMAT. TomoTherapy offered superior plan quality but required the longest delivery time.

Comprehensive leaf size traits dataset for seven plant species from digitised herbarium specimen images covering more than two centuries.

BACKGROUND: Morphological leaf traits are frequently used to quantify, understand and predict plant and vegetation functional diversity and ecology, including environmental and climate change responses. Although morphological leaf traits are easy to measure, their coverage for characterising variation within species and across temporal scales is limited. At the same time, there are about 3100 herbaria worldwide, containing approximately 390 million plant specimens dating from the 16th to 21st century, which can potentially be used to extract morphological leaf traits. Globally, plant specimens are rapidly being digitised and images are made openly available via various biodiversity data platforms, such as iDigBio and GBIF. Based on a pilot study to identify the availability and appropriateness of herbarium specimen images for comprehensive trait data extraction, we developed a spatio-temporal dataset on intraspecific trait variability containing 128,036 morphological leaf trait measurements for seven selected species. NEW INFORMATION: After scrutinising the metadata of digitised herbarium specimen images available from iDigBio and GBIF (21.9 million and 31.6 million images for Tracheophyta; accessed date December 2020), we identified approximately 10 million images potentially appropriate for our study. From the 10 million images, we selected seven species (Salix bebbiana Sarg., Alnus incana (L.) Moench, Viola canina L., Salix glauca L., Chenopodium album L., Impatiens capensis Meerb. and Solanum dulcamara L.) , which have a simple leaf shape, are well represented in space and time and have high availability of specimens per species. We downloaded 17,383 images. Out of these, we discarded 5779 images due to quality issues. We used the remaining 11,604 images to measure the area, length, width and perimeter on 32,009 individual leaf blades using the semi-automated tool TraitEx. The resulting dataset contains 128,036 trait records.We demonstrate its comparability to trait data measured in natural environments following standard protocols by comparing trait values from the TRY database. We conclude that the herbarium specimens provide valuable information on leaf sizes. The dataset created in our study, by extracting leaf traits from the digitised herbarium specimen images of seven selected species, is a promising opportunity to improve ecological knowledge about the adaptation of size-related leaf traits to environmental changes in space and time.

Leaf size estimation based on leaf length, width and shape.

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

A kelch-repeat superfamily gene, ZmNL4, controls leaf width in maize (Zea mays L.).

Leaf width (LW) is an important component of plant architecture that extensively affects both light capture during photosynthesis and grain yield, particularly under dense planting conditions. However, the genetic and molecular mechanisms regulating LW remain largely elusive in maize (Zea mays L.). In this study, qLW4a, a major quantitative trait locus controlling LW, was identified in a population constructed with maize inbred lines PH6WC, with wide leaves, and Lin387, with narrow leaves. Map-based cloning revealed that ZmNL4, a kelch-repeat superfamily gene, emerged to be the candidate for qLW4a, and a single-base deletion in the conserved SMC_prok_B domain of ZmNL4 in Lin387 caused a frame shift, leading to premature termination. Consistently, the knockout of ZmNL4 by CRISPR/Cas9 editing significantly reduced the LW, which was attributed to a reduction in the cell number instead of cell size, indicating a role of ZmNL4 in regulating cell division. Transcriptomic comparison of ZmNL4 knockout lines with the wild type B73-329 revealed that ZmNL4 might participate in cell wall biogenesis, asymmetric cell division, metabolic processes, transmembrane transport and response to external stimulus, etc. These results provide insights into the genetic and molecular mechanisms of ZmNL4 in controlling LW and could potentially contribute to optimizing plant architecture for maize breeding.

Half-leaf width symmetric distribution reveals buffering strategy of Cunninghamia lanceolata.

BACKGROUND: Leaf length and width could be a functioning relationship naturally as plant designs. Single-vein leaves have the simplest symmetrical distribution and structural design, which means that fast-growing single-vein species could interpret the scheme more efficiently. The distribution of leaf length and width can be modulated for better adaptation, providing an informative perspective on the various operational strategies in an emergency, while this mechanism is less clear. Here we selected six age groups of Cunninghamia lanceolata pure forests, including saplings, juveniles, mature, and old-growth trees. We pioneered a tapering model to describe half-leaf symmetric distribution with mathematical approximation based on every measured leaf along developmental sequence, and evaluated the ratio of leaf basal part length to total length (called tipping leaf length ratio). RESULTS: The tipping leaf length ratio varied among different tree ages. That means the changes of tipping leaf length ratio and leaf shape are a significant but less-noticed reflection of trees tradeoff strategies at different growth stages. For instance, there exhibited relatively low ratio during sapling and juvenile, then increased with increasing age, showing the highest value in their maturity, and finally decreased on mature to old-growth transition. The tipping leaf length ratio serves as a cost-benefit ratio, thus the subtle changes in the leaf symmetrical distribution within individuals reveal buffering strategy, indicating the selection for efficient design of growth and hydraulic in their developmental sequences. CONCLUSIONS: Our model provides a physical explanation of varied signatures for tree operations in hydraulic buffering through growth stages, and the buffering strategy revealed from leaf distribution morphologically provides evidence on the regulation mechanism of leaf biomechanics, hydraulics and physiologies. Our insight contributes greatly to plant trait modeling, policy and management, and will be of interest to some scientists and policy makers who are involved in climate change, ecology and environment protection, as well as forest ecology and management.

OsJAZ9 is involved in water-deficit stress tolerance by regulating leaf width and stomatal density in rice.

Drought stress poses a severe threat to grain yield in rice. Our previous report demonstrated the role of OsJAZ9 in potassium homeostasis by modulating Jasmonic Acid (JA) signalling. While both potassium (K) and JA are known to have an important role in drought stress response, JA's repressor, i.e., JAZs' role in drought stress, remains elusive. Here we report that OsJAZ9 plays a critical role in rice water-deficit stress tolerance via influencing JA and ABA signalling. Overexpression of OsJAZ9 led to the enhanced ABA and JA levels. Our data further revealed that exogenous JA application antagonises the ABA-mediated inhibition of seed germination. Further, OsJAZ9 overexpression reduces leaf width and stomata density, leading to lower leaf transpiration rates than WT. This reduced transpiration and higher K content as osmoticum improved the water-deficit stress tolerance in OsJAZ9 overexpression lines. On the contrary, OsJAZ9 RNAi lines displayed enhanced sensitivity towards water-deficit stress. Our data provide new insights on the role of JA signalling repressors in rice response to water-deficit stress.

Nondestructive estimation of leaf area for 15 species of vines with different leaf shapes.

PREMISE: The nondestructive measurement of leaf area is important for expediting data acquisition in the field. The Montgomery equation (ME) assumes that leaf area (A) is a proportional function of the product of leaf length (L) and width (W), i.e., A = cLW, where c is called the Montgomery parameter. The ME has been successfully applied to calculate the surface area of many broad-leaved species with simple leaf shapes. However, whether this equation is valid for more complex leaf shapes has not been verified. METHODS: Leaf A, L, and W were measured directly for each of 5601 leaves of 15 vine species, and ME and three other models were used to fit the data. All four models were compared based on their root mean square errors (RMSEs) to determine whether ME provided the best fit. RESULTS: The ME was a reliable method for estimating the A of all 15 species. In addition, the numerical values of 13 of the 15 values of c fell within a previously predicted numerical range (i.e., between 1/2 and π/4). The data show that the numerical values of c are largely affected by the value of W/L, the concavity of the leaf base, and the number of lobes on the lamina. CONCLUSIONS: The Montgomery parameter can reflect the influence of leaf shape on leaf-area calculations and can serve as an important tool for nondestructive measurements of leaf area for many broad-leaved species and for the investigation of leaf morphology.

Gibberellin Enhances the Anisotropy of Cell Expansion in the Growth Zone of the Maize Leaf.

Although plant organ shapes are defined by spatio-temporal variations of directional tissue expansion, this is a little characterized aspect of organ growth regulation. Although it is well known that the plant hormone gibberellin increases the leaf length/with ratio, its effects on cell expansion in the growing leaf are largely unknown. To understand how variations in rate and anisotropy of growth establish the typical monocotelydonous leaf shape, we studied the leaf growth zone of maize (Zea mays) with a kinematic analysis of cell expansion in the three directions of growth: proximo-distal, medio-lateral, and dorso-ventral. To determine the effect of gibberellin, we compared a gibberellin-deficient dwarf3 mutant and the overproducing UBI::GA20OX-1 line with their wild types. We found that, as expected, longitudinal growth was dominant throughout the growth zone. The highest degree of anisotropy occurred in the division zone, where relative growth rates in width and thickness were almost zero. Growth anisotropy was smaller in the elongation zone, due to higher lateral and dorso-ventral growth rates. Growth in all directions stopped at the same position. Gibberellin increased the size of the growth zone and the degree of growth anisotropy by stimulating longitudinal growth rates. Inversely, the duration of expansion was negatively affected, so that mature cell length was unaffected, while width and height of cells were reduced. Our study provides a detailed insight in the dynamics of growth anisotropy in the maize leaf and demonstrates that gibberellin specifically stimulates longitudinal growth rates throughout the growth zone.

Effects of shade on guinea grass genotypes Megathyrsus maximus (Poales: Poaceae)

Introduction: Light stress is an important factor limiting the biomass yield while combining forage production with crops or forestry. Guinea grass is a widely adapted perennial fodder grass. The species exhibits high degree of variation for morphology, adaptation and biomass yield. Objective: Since there is a need in identifying shade adapted forage grasses for the expanding area under agroforestry/silvipastures, the present investigation took the task of understanding how the morphologically distinct genotypes of guinea grass respond under different shaded intensities. Methods: In the present study, forty-four genotypes related with the shade response were studied in varying shading conditions (pure sunlight, 25, 50 and 75 % shade) created artificially. Results: Based on green and dry matter yields ranking, the genotype IG 01-98 performed the best followed by genotypes IG 01-92, IG 97-5, IG 97-6 and IG 01-89 in decreasing order. Particularly, IG 01-93 was identified as the best performing under 50 % shading conditions. On the other hand, most of the top ranking genotypes performed well both under open and up to 50 % of shade. Morphologically, these genotypes were taller and possessed longer and broader leaves. Under shaded conditions (over 50 %), leaf length and width showed an increasing trend compared to open conditions. Also, chlorophyll content increased with shading intensity. Conclusions: Most of the genotypes collected from the southern Indian humid tropical environment with early flowering nature were tolerant to shade. Differential genotypic response was observed for biomass yield and yield attributes under shade. The study established appreciable variability for shade tolerance among genotypes.

Introducción: El estrés leve es un factor importante que limita el rendimiento de la biomasa al tiempo que combina laproducción forrajera con los cultivos o la silvicultura. El zacate guinea es una planta de forraje perenne ampliamente adaptada. La especie presenta un alto grado de variación en su morfología, adaptación y rendimiento de biomasa. Objetivo: Como existe la necesidad de la identificación de pastos forrajeros adaptados a la sombra para el área de expansión bajo agroforestería /silvicultura, la presente investigación se realizó para entender cómo los genotipos morfológicamente distintos al zacate guinea responden a diferentes intensidades de sombra. Métodos: Se estudiaron 44 genotipos y su respuesta a los niveles de sombra: luz solar pura y 25, 50 y 75 % de sombra (creados artificialmente). Resultados: Basado en la clasificación de rendimientos demateria verde y seca, el genotipo IG 01-98 fue el mejor, seguido de los genotipos IG 01-92, IG 97-5, IG 97-6 e IG 01-89 en orden decreciente. Por su parte, el IG 01-93 fue identificado como el de mayor rendimiento bajo el 50 % de condición de sombra. La mayoría de los genotipos de primer nivel tuvieron un buen desempeño, tanto bajo sombra abierta como al 50 %. Morfológicamente, estos genotipos fueron más altos y poseían hojas más largas y más anchas. En condiciones de sombra, de más del 50 %, la longitud y ancho de la hoja mostraron una tendencia creciente en comparación con la condición abierta. El contenido de clorofila aumentó con la intensidad de la sombra. Conclusiones: La mayoría de los genotipos recolectados al sur de la India en un ambiente tropical húmedo y tienen una floración temprana, fueron tolerantes a la sombra. Se observó una respuesta genotípica diferencial para los atributos de rendimiento y rendimiento de biomasa bajo sombra. El estudio mostró la existencia de una variabilidad apreciable para la tolerancia a la sombra entre los genotipos.

Feasibility of 5-mm vs 2.5-mm width multileaf collimator in noncoplanar volumetric modulated arc stereotactic radiotherapy for multiple brain metastases.

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.

The effect of MLC leaf width in single-isocenter multi-target radiosurgery with volumetric modulated arc therapy.

PURPOSE: Single-isocenter multi-target (SIMT) volumetric modulated arc therapy (VMAT) is primarily limited to linear accelerators utilizing 2.5 mm leaf width MLCs. We explore feasibility of applying this technique to linear accelerators utilizing MLCs with leaf width of 5 mm. METHODS: Twenty patients with 3-10 intracranial brain metastases originally treated with 2.5 mm MLCs were re-planned using 5 mm MLCs and relevant dosimetric indices were compared. We also evaluated various strategies of adding VMAT arcs to mitigate degradations of dose quality values. RESULTS: Wider MLCs caused small changes in total MUs (5827 ± 2334 vs 5572 ± 2220, p = 0.006), and conformity index (CI) (2.22% ± 0.05%, p = 0.045), but produced more substantial increases in brain V30%[%] and V50%[%] (27.75% ± 0.16% and 20.04% ± 0.13% respectively, p < 0.001 for both), and V12Gy[cc] (16.91% ± 0.12%, p < 0.001). CONCLUSION: SIMT radiosurgery delivered via VMAT using 5 mm wide MLCs can achieve similar CI compared to that using 2.5 mm leaf width MLCs but with moderately increased isodose spill, which can be only partially mitigated by increasing the number of VMAT arcs.