Leaf Pairs Research Articles

Facing energy limitations - approaches to increase basil (Ocimum basilicum L.) growth and quality by different increasing light intensities emitted by a broadband LED light spectrum (400-780 nm).

Based on the current trend towards broad-bandwidth LED light spectra for basil productions in multi-tiered controlled-environment horticulture, a recently developed white broad-bandwidth LED light spectrum (400-780 nm) including far-red wavelengths with elevated red and blue light fractions was employed to cultivate basil. Four Ocimum basilicum L. cultivars (cv. Anise, cv. Cinnamon, cv. Dark Opal and cv. Thai Magic) were exposed to two different rising light intensity conditions (ILow and IHigh). In dependence of the individual cultivar-specific plant height increase over time, basil cultivars were exposed to light intensities increasing from ~ 100 to ~ 200 µmol m-2 s-1 under ILow, and from 200 to 400 µmol m-2 s-1 under IHigh (due to the exponential light intensity increases with decreasing proximity to the LED light fixtures). Within the first experiment, basils' morphological developments, biomass yields and time to marketability under both light conditions were investigated and the energy consumptions were determined to calculate the basils' light use efficiencies. In detail, cultivar-dependent differences in plant height, leaf and branch pair developments over time are described. In comparison to the ILow light conditions, IHigh resulted in accelerated developments and greater yields of all basil cultivars and expedited their marketability by 3-5 days. However, exposure to light intensities above ~ 300 µmol m-2 s-1 induced light avoidance responses in the green-leafed basil cultivars cv. Anise, cv. Cinnamon and cv. Thai Magic. In contrast, ILow resulted in consumer-preferred visual qualities and greater biomass efficiencies of the green-leafed basil cultivars and are discussed as a result of their ability to adapt well to low light conditions. Contrarily to the green-leafed cultivars, purple-leafed cv. Dark Opal developed insufficiently under ILow, but remained light-tolerant under IHigh, which is related to its high anthocyanin contents. In a second experiment, cultivars' volatile organic compound (VOC) contents and compositions over time were investigated. While VOC contents per gram of leaf dry matter gradually decreased in purple-leafed cv. Dark Opal between seedling stage to marketability, their contents gradually increased in the green cultivars. Regardless of the light treatment applied, cultivar-specific VOC compositions changed tremendously in a developmental stage-dependent manner.

A Sparse Orthogonal Collimators System for Experiments on Small-Animal Scale

<h3>Purpose/Objective(s)</h3> Intensity-modulated radiotherapy (IMRT) is the clinical gold standard for concentrated dose delivery. However, IMRT for small animal experiments has faced paramount technical challenges, preventing effective clinical translation of preclinical experiments. Sparse orthogonal collimator (SOC) based on the Rectangular Aperture Optimization (RAO) framework is the first general-purpose small animal IMRT platform, but its original planning algorithm was inefficient for complex cases such as total marrow irradiation (TMI) of mice. Here we introduce a significantly improved optimization framework for efficient SOC-based treatment planning and demonstrate TMI efficacy. <h3>Materials/Methods</h3> The SOC system is designed and fabricated with four orthogonal, double-focused tungsten leaf pairs that are capable of forming two rectangles simultaneously. The rectangles were optimized using RAO. Since the Kronecker product representation of the rectangular aperture is the main limitation of the computational performance, we reformulated matrix multiplication in the data fidelity term using multiplication with small matrices instead of the Kronecker product of the matrices. The optimization problem can then be efficiently solved using the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). Five mice CTs with manually delineated bone marrow and OARs, including the kidneys, lungs, heart, spleen, liver and bowel, were used in the planning study. 12 Gy was prescribed to the bone marrow target while expecting the bones to receive 2.5X higher doses due to kV photoelectric interactions. RAO plans were compared with manual 3D plans with custom lead blocks. <h3>Results</h3> SOC plans markedly improved TMI PTV hot spots and significantly reduced OAR doses compared with other experimental data. The PTV D5, indicating the maximum dose, was reduced by 21.6%. The average doses to the kidneys, lungs, heart, liver, and bowel were reduced by 98.4%, 95.7%, 79.1%, 97.7%, and 82.8%. The average plan optimization total time was 40 minutes. <h3>Conclusion</h3> This study shows the feasibility of creating SOC-based RAO plans for complex and large targets such as TMI. The marked improvement in OAR sparing allows mouse experiments to more closely simulate human treatments, which is critical for TMI, whose treatment response and outcome heavily depend on both the target and off-target doses and toxicity.

Screening Table Beet and Swiss Chard for Resistance to Pseudomonas syringae pathovar aptata

Bacterial leaf spot (BLS) has emerged in the last few decades as an economically important disease of both table beet (Beta vulgaris ssp. vulgaris) and Swiss chard (Beta vulgaris ssp. cicla). BLS is caused by Pseudomonas syringae pv. aptata, which is spread readily on infected seeds. Symptoms appear as circular to irregular shaped, with a tan to dark brown center and a very dark border. Disease incidence and severity is dependent on cool, humid conditions and can vary widely year to year depending on the environment. Both the vegetative and reproductive phases of these biennial crops are susceptible to the pathogen. Table beet and Swiss chard commercial cultivars (n = 21), table beet breeding lines (n = 5), and table beet plant introductions (PIs) (n = 26) were screened for response to spray inoculation with P. syringae pv. aptata in a controlled greenhouse setting. Plants were rated for severity of symptoms using percent of the area of each pair of leaves (leaf set) with symptoms and an overall plant score assigned based on the scores for each leaf pair. Accessions varied in BLS susceptibility. PI accessions were most variable, with the area under the disease progress curve (AUDPC) ranging from 1.33 to 8.75. Highly significant differences among PIs were detected for disease scores in the vegetative stage, beginning 21 days after inoculation. Screens during the reproductive growth stage showed the least variation in AUDPC among PIs. Although cultivars varied less than PIs, good BLS resistance (low disease scores) was noted for ‘Touchstone Gold’, ‘Kestrel’, ‘Bull’s Blood’, ‘Rainbow’ chard, as well as PIs 222234 and NSL 28026. Accessions W451C, Red Cloud, Detroit Dark Red, and NSL 28020 were highly susceptible. There was no consistent association between disease score in the vegetative and reproductive phases, suggesting that breeders may need to screen for BLS in both phases of the biennial life cycle. The more resistant PIs or cultivars identified in this study can be used in future efforts to breed for host resistance to BLS and to establish mapping populations to better understand the genetic control of resistance, to aid in breeding efforts.

Sideritis elica, a New Species of Lamiaceae from Bulgaria, Revealed by Morphology and Molecular Phylogeny.

Sideritis elica, from the Rhodope Mountains, is described as a species new to science. Results of a detailed morphological analysis were combined with the data of molecular analyses using DNA barcoding as an efficient tool for the genetic, taxonomic identification of plants. The combination of morphological features distinguishes the new species well: Its first three uppermost leaf pairs are significantly shorter and wider, the branchiness of the stems is much more frequent, the whole plant is much more lanate, and it looks almost white, as opposed to the other closed species of section Empedoclia, which look grayish green. The molecular analysis, based on the rbcL and trnH-psbA regions, supports the morphological data about the divergence of Sideritis scardica and Sideritis elica. The studied populations of the two taxa were found to be genetically distant (up to 6.8% polymorphism for trnH-psbA) with distinct population-specific nucleotide patterns, while no polymorphism in the DNA barcodes was detected within the Sideritis elica population. The results confirm the existence of a new species called Sideritis elica, which occurs in the nature reserve Chervenata Stena, located in the northern part of the Central Rhodope Mountains. There were only 12 individuals found in the locality, which underlines the necessity of conservation measures.

Portal dosimetry correction method for validation of single isocenter VMAT plans for multiple brain metastases.

Portal dosimetry is one option for verification of volumetric‐modulated arc therapy (VMAT) planning for multiple brain metastases. However, due to the changing response of the portal imager with photon beam energy, the dose transmitted through closed multileaf collimator (MLC) leaves or narrow MLC gaps may be underestimated by the imager.We present a simple method for correcting for these effects that may be implemented within the Eclipse treatment planning system. We recalculated the predicted portal dose with and without this correction for 20 multiple brain met VMAT plans. Before the correction, 3/20 composite plan fields passed our standard quality assurance (QA) criteria (54/80 individual fields); the average gamma passing rate for the composite plans was 76.9 ± 16.6%, and the average gamma value across the composite plans was 0.67 ± 0.23. After correction, 20/20 composite plan fields passed the QA criteria (80/80 individual fields); the average gamma passing rate for composite plans was 99.2 ± 1.4%, the average gamma value across the composite plans was 0.33 ± 0.90. A measure of plan complexity, the average leaf pair opening could be correlated to the gamma analysis results for the uncorrected plans but not for the corrected plans.

Application of bacterial agents on sunflower

The study was aimed to examine the effects of bacterial agents combined with two variants of mineral fertilization on the sunflower yield.&#x0D; Materials and methods. The main field experiments were carried out in Department of Plant Production and Variety Investigations of the Plant Production Institute named after V.Ya. Yuriev of NAAS of Ukraine in 2016−2018.&#x0D; The soil was deep granular slightly leached chernozem. It had the following agrochemical parameters: humus content (Tyurin’s method) 5.8%; pH 5.8; hydrolytic acidity 3.29 mg/eq per 100 g of soil. The nutrient reserves in the control (no fertilizer): nitrogen – 132 mg/kg; phosphorus – 104 mg/kg; potassium – 128 mg/kg. The nutrient amounts with mineral fertilizer (N30P30K30): nitrogen – 130-140 mg/kg; phosphorus – 180−200 mg/kg; potassium – 170−190 mg/kg of soil.&#x0D; Data were statistically processed by variance and correlation analyses.&#x0D; Results and discussion. In2016-2018, sunflower plants grew and developed under very contrasting weather conditions compared to the multi-year averages. There was a water deficit during the critical periods (anthesis, seed setting and filling), especially at elevated air temperatures.&#x0D; In the study, biofertilizer GroundFix + bacterial agent HelpRost turned out to be the most effective combination. When GroundFix was used at a dose of 5 L/ha without fertilizer, the yield increased by 0.33 t/ha compared to the control; when it was used with N30P30K30 as basic fertilizer, the gain in the yield amounted to 0.36 t/ha. When the ‘GroundFix 5 L/ha + HelpRost’ combination was applied, the gain was 0.30 and 0.32 t/ha, respectively. The efficiency of HelpRost 3 L/ha in the “5−6 leaf pair” phase of the crop was -0.03 and -0.04 t/ha on the respective mineral fertilization. When the biofertilizer dose was increased to 8 L/ha, the yield was raised by 0.32 and 0.30 t/ha, respectively; when the increased dose was co-applied with HelpRost, the increment was 0.42 and 0.58 t/ha, respectively.&#x0D; There was a strong positive effect of April temperatures on the yield, with correlation coefficient of 0.36− 0.72, and of June temperatures (r = 0.33−0.59), except for the ‘GroundFix 5 L/ha + HelpRost 3 L/ha’ combination on basic fertilization with N30P30K30 (r = - 0.25 and r = - 0.07, respectively).&#x0D; Conclusions. When GroundFix was used at a dose of 5 L/ha without fertilizer, the yield increment was 0.33 t/ha compared to the control; when GroundFix was used at the same dose with N30P30K30, the increment amounted to 0.36 t/ha. By combining GroundFix 5 L/ha with HelpRost, we obtained the yield increments of 0.30 and 0.32 t/ha, respectively. Increasing the biofertilizer dose to 8 L/ha gave the yield gain of 0.32 and 0.30 t/ha, respectively. When the increased dose was co-applied with HelpRost, the gain was 0.42 and 0.58 t/ha, respectively.&#x0D; There was a positive correlation (r = 0.37−1.00) between the yield and precipitation amount during the growing period. We noted a strong positive effect of April temperatures, with correlation coefficient of 0.36−0.72, and of June temperatures (r = 0.33−0.59). &#x0D;

Evaluation of QA software system analysis for the static picket fence test.

Intensity modulation treatments are widely used in radiotherapy because of many known advantages. In this context, the picket fence test (PF) is a relevant test to check the Multileaf Collimator (MLC) performances. So this work compares and evaluates three analysis platforms for the PF used routinely by three different institutions. This study covers two linear accelerators (Linac) with two MLC types, a Millenium 120 MLC and Millenium 120 High Definition MLC respectively on a Varian Truebeam and Truebeam STx. Both linacs include an As 1200 portal imager (EPID). From a reference PF plan, MLC errors have been introduced to modify the slits in position or width (shifts from 0.1 to 0.5 mm on one or both banks). Then errors have been defined on the EPID to investigate detection system deviations (signal sensitivity and position variations). Finally, 110 DICOM‐RT images have been generated and analyzed by each software system. All software systems have shown good performances to quantify the position errors, even though the leaf pair identifications can be wrong in some cases regarding the analysis method considered. The slit width measurement (not calculated by all software systems) has shown good sensitivity, but some quantification difficulties have been highlighted regardless of the analysis method used. Linked to the expected accuracy of the PF test, the imager variations have demonstrated considerable influence in the results. Differences in the results and the analysis methods have been pointed out for each software system. The results can be helpful to optimize the settings of each analysis software system depending on expectations and treatment modalities of each institution.

Potential of the coffee endophytic Bacillus cereus sensu lato strain CCBLR15 to control the plant-parasitic nematode Radopholus duriophilus

ABSTRACT Bacillus cereus sensu lato strain CCBLR15 is highly efficient in inducing in vitro the mortality of coffee-parasitic nematodes, including Pratylenchus coffeae and Radopholus duriophilus. In the present study, this strain was further characterised to investigate (1) its taxonomic position, (2) the secreted/non-secreted nature of its nematicidal compounds, and (3) its in planta biocontrol capacity towards R. duriophilus. Firstly, analysis of 16S rRNA gene sequences and motility test indicated that CCBLR15 was closely related to B. cereus sensu stricto. Secondly, nematodes separate expositions in vitro to CCBLR15 culture filtrate and cell lysate revealed that nematicidal activity was attributed to compounds released after bacterial cell lysis. Thirdly, CCBLR15 nematode biocontrol capacity was studied using three Coffea arabica cultivars, either seed- or cutting-propagated. Plants were therefore characterised by different developmental stages, referred to as ‘early' and ‘advanced', with respectively 2-3 and 6-8 leaf pairs. Additionally, plants were grown in unsterilised soil, with a one-month delay between inoculations of bacteria and nematodes to assess the persistence of the nematicidal effects. The presence of R. duriophilus in roots decreased plant growth only in one cultivar whose plants were inoculated at the ‘early' stage. Nonetheless, CCBLR15 pre-inoculation significantly reduced the number of nematodes in roots of all cultivars and inhibited the negative effects of nematodes in ‘early’-inoculated plants. These results demonstrate the capacity of CCBLR15 to control R. duriophilus and constitute an important step before studying the persistence of its biocontrol effects on a longer period or after plants establishment in the field.

Response of Shoot Pruning on Growth, Flowering and Fruiting Characteristics of Guava under Sub-Himalayan Terai Region of West Bengal

Guava is one of the important fruit crops grown worldwide. Shoot pruning improves the emergence of new flush and its role on flowering and fruiting characteristics was evaluated on this experiment. The effect on shoot pruning height and removal of top leaf bud by pinching was assessed on growth, flowering and fruiting characteristics of guava cv. L-49. The experiment was conducted at Uttar Banga Krishi Viswavidyalaya There were two factors heading back and pinching. Heading back at the level of, Pundibari, Cooch Behar, West Bengal. 90, 120 and 150cm was done in January and pinching of one leaf pair was performed during the last week of June, 2018.The heading back at the level of 120 cm and no pinching were most effective for number of flowering bud (179.33), number of flowers (139.83), number of fruit set (95.33), total number of fruits (64.66), ascorbic acid (190.35 mg/100g), titratable acidity (0.28%) and heading back at the level of 120 cm and one pinching were effective in increasing number of primary shoots (39.50), flowering percentage (80.18%), fruit weight (172.00g).

Solução de aminoácidos no crescimento da planta ornamental Impatiens walleriana sob estresse de restrição de desenvolvimento radicular

Abstract The use of amino acid solutions as bio-fertilizers was introduced in the food and ornamental plant industry about two decades ago. Sprays containing amino acids either alone or combined have been proven effective to increase plant growth. However, many of the new commercial solutions including amino acids as bio-fertilizers have no published data available on bedding plants. Thus, the aims of this study were to determine the changes in fresh weight accumulation in the bedding pot plant Impatiens walleriana and the physiological mechanism involved in plants sprayed with different amino acid solutions and to characterize the responses to root restrictions under nursery with non-limited nitrogen supply. The experiment was carried out inside a greenhouse in the campus of the Faculty of Agronomy of the University of Buenos Aires, Argentina. To reach the objectives, Impatiens walleriana ‘Xtreme White’ seeds were grown in 50-cell (55.7 cm3 cell-1) and 288-cell (6.18 cm3 cell-1) plug trays and then transplanted and grown at 3-L pots. Eleven solutions (100 mg L-1) containing an equal amount of each of the following amino acids: alanine, cysteine, aspartic acid, glutamic acid, glycine, leucine, lysine, methionine, threonine, tryptophan and valine, a control without amino acids, and a solution containing all amino acids (Mix) (9.1 mg L-1 of each amino acid) were sprayed when the first true leaf pair was developed. Our results showed that the different synthetic amino acids tested, alone or combined, had additive and antagonistic effects on the leaf area and fresh-dry weight in Impatiens walleriana plants.

Molecular and Morphological Analysis Supports the Separation ofRobrichiaas a Genus Distinct fromEnterolobium(Leguminosae: Caesalpinioideae: Mimosoid Clade)

Abstract—As currently circumscribed, the legume genusEnterolobiumcomprises 11 species in two sections:E.sect.EnterolobiumandE.sect.Robrichia, with an overall distribution from Mexico to Argentina and a centre of diversity in Amazonia. In the absence of the characteristic indehiscent fruits,Enterolobiumis difficult to distinguish from other genera in the ingoid clade, includingAlbiziasensu lato,Samanea, andCathormion. Previous phylogenetic studies which have includedEnterolobiumhave sampled few species of the genus, leaving questions about its monophyly and interspecific relationships. Here we evaluate the circumscription ofEnterolobiumand its two infrageneric taxa, their phylogenetic placement in the ingoid clade, and interspecific relationships within the two sections of the genus. Our study includes allEnterolobiumspecies, and analyses of nuclear (ITS and ETS) and plastid (trnD-TandtrnL-F) molecular regions, and morphology. Bayesian inference, maximum parsimony, and maximum likelihood analyses show thatEnterolobium, as presently circumscribed, is not monophyletic. The genus is divided into two well-supported independent clades, corresponding to the two previously recognized sections; one of them is sister to the genusLeucochloronand is here raised to generic rank as the genusRobrichia, with three species,Robrichia glaziovii,Robrichia oldemaniiandRobrichia schomburgkii. The genusEnterolobiumconsequently now comprises eight species and is more closely related to a clade composed ofAlbiziaandFalcataria. This new arrangement is reinforced by morphological synapomorphies recovered by ancestral character state reconstructions. Indumentum type, the number of pinnae pairs per bipinnate leaf and leaflet pairs per pinna, inflorescence type, and fruit shape characterizeRobrichia, while the recognition ofEnterolobiumremains based on fruit traits. We also provide the formal lectotypifications forE. contortisiliquum,E. cyclocarpum,E. gummiferum,E. maximum,E. monjollo, andR. schomburgkii.

SEEDLING AND GROWTH OF Rhizophora mangle L. PROPAGULES AT A RESTORATION SITE (APA DE GUAPI-MIRIM - RJ)

One of the biggest mangrove forests in Rio de Janeiro is located at Guanabara Bay. However, a large part of this ecosystem is currently suppressed and only 1/3 of the original 261.90 km² of mangrove vegetation can be observed. Thus, several conservation and management actions are conducted in this ecosystem. Studying plantations and other restoration strategies for this biome is important to understand the dynamics of this ecosystem and enhance such strategies. Size can be one of the most important characteristics for propagules success. Some studies state that larger seedlings can resist more and have greater survival than smaller seedlings. Therefore, this study aims to analyze the germination and development of Rhizophora mangle L. propagules at an in situ plantation in the mangroves of the Guapi-Mirim Environmental Protection Area. A total of nine plots were delimited with spacing of 4 meters by 1 meter each in which Rhizophora mangle propagules were separated into small and large groups and planted. Their germination and development were subsequently monitored for a period of 6 months. The diameter, height and initial weight of the propagules and the increase in height and diameter at 76, 93 and 154 days after planting were measured. Periodic observations were made approximately every 20 days in order to quantify the rate and type of mortality (predation, water current carriage and drying) and to monitor time (in days) of pairs of leaves opening. There were no differences between the propagules according to the size for the opening time of leaf pairs, nor for the mortality rate. The increments in diameter and height were larger for the small propagules in the first development periods, but not in the last ones. The large and small propagules did not show significant differences in diameter or height at 154 days. There was high mortality of small propagules due to predation and/or water current carriage, while the mortality for large propagules was higher due to desiccation. The results generally suggest there is no difference in the survival and development of the propagules related to size, as they are more affected by local ecological conditions.

Assessment of the host-range and impact of the mite, Aculus crassulae, a potential biological control agent for Australian swamp stonecrop, Crassula helmsii

The non-native aquatic weed Crassula helmsii, or Australian swamp stonecrop, has become widespread and a major problem in aquatic habitats in the UK and North-West Europe, with negative impacts reported from ecologically important habitats. As very few effective traditional management tools are available to land managers, a biological control project was initiated in the UK. An Australian phytophagous mite, Aculus crassulae (Acari: Eriophyidae) was evaluated as a potential agent for C. helmsii under laboratory conditions in no-choice and choice host plant tests. These demonstrated that A. crassulae is host specific to C. helmsii, with only minor exploratory feeding observed on the native congener, C. aquatica, under no-choice tests, and no damage recorded in choice tests. The impact of A. crassulae on the growth of C. helmsii was also investigated by applying two different mite densities to plants. Both densities, especially the higher mite density, caused a significant reduction in plant growth by the end of the experimental period. Secondary shoot number and length, number of nodes and new leaf pairs were reduced by the mites during the course of the experiment, but the largest impact was on the reduction of plant height. The host specific nature of A. crassulae and the observed reduction in these significant growth parameters demonstrate the potential A. crassulae has as a biological control agent for C. helmsii in the UK and Europe.

A strategy to determine off-axis dosimetric leaf gap using OSLD and EPID.

BackgroundThe aim of the study was to investigate the dosimetric feasibility of using optically stimulated luminescence dosimeters (OSLD) and an electronic portal imaging device (EPID) for central axis (CA X) and off-axis (OAX) dosimetric leaf gap (DLG) measurement.Materials and methodsThe Clinac 2100C/D linear accelerator equipped with Millennium-120 multileaf collimator (MLC) and EPID was utilized for this study. The DLG values at CA X and ± 1 cm OAX (1 cm superior and inferior to the CA X position, respectively along the plane perpendicular to MLC motion) were measured using OSLD (DLGOSLD) and validated using ionization chamber dosimetry (DLGICD). The two-dimensional DLG map (2D DLGEPID) was derived from the portal images of the DLG plan using a custom-developed software application that incorporated sliding aperture-specific correction factors.ResultsDLGOSLD and DLGICD, though measured with diverse setup in different media, showed similar variation both at CA X and ± 1 cm OAX positions. The corresponding DLGEPID values derived using aperture specific corrections were found to be in agreement with DLGOSLD and DLGICD. The 2D DLGEPID map provides insight into the varying patterns of the DLG with respect to each leaf pair at any position across the exposed field.ConclusionsCommensurate results of DLGOSLD with DLGICD values have proven the efficacy of OSLD as an appropriate dosimeter for DLG measurement. The 2D DLGEP ID map opens a potential pathway to accurately model the rounded-leaf end transmission with discrete leaf-specific DLG values for commissioning of a modern treatment planning system.

Differentiation of valuable for breeding sunflower lines by resistance to Phoma rot

The purpose of the research is differentiation of valuable for breeding sunflower lines by resistance to Phoma rot. The promising constant sunflower lines were estimated by their resistance to Phoma rot using methods of artificial inoculation in the greenhouse and laboratory conditions. In greenhouse conditions, there were used two methods of artificial inoculation with a fungus Plenodomus lindquistii in the bottom of leaf petiole of a sunflower plant at a stage of the first true leaf pair. Application of the pieces of agar nutrient medium with mycelium, pycnidia and picnospores (unbroken) allowed to identify resistant and mid-resistant sunflower lines (VK 900, L 86 and L 107, L 132). At inoculation with 0.2 ml of a fungus spore suspension (concentration of 1 × 106 spores/ml), five susceptible and one very susceptible sunflower lines (L 2385, L 103, L 136, L 131, L 128, and L 82) were determined. In laboratory conditions, the quick test for estimation of susceptibility to Phoma rot (dose of infection – 12 g) allowed to reveal more than 50 % of plants with healthy root system and two constant sunflower lines L 116 and L 136 with the affection degree of one point. Estimation of susceptibility to Phoma rot infection of the different organs (stem and root system) at artificial inoculation showed a possibility to differentiate sunflower lines by resistance of roots and stems and to select the most promising for the further work in breeding.

Evaluation of the ability of three commercially available dosimeters to detect systematic delivery errors in step-and-shoot IMRT plans.

There is limited data on error detectability for step-and-shoot intensity modulated radiotherapy (sIMRT) plans, despite significant work on dynamic methods. However, sIMRT treatments have an ongoing role in clinical practice. This study aimed to evaluate variations in the sensitivity of three patient-specific quality assurance (QA) devices to systematic delivery errors in sIMRT plans. Four clinical sIMRT plans (prostate and head and neck) were edited to introduce errors in: Multi-Leaf Collimator (MLC) position (increasing field size, leaf pairs offset (1-3 mm) in opposite directions; and field shift, all leaves offset (1-3 mm) in one direction); collimator rotation (1-3 degrees) and gantry rotation (0.5-2 degrees). The total dose for each plan was measured using an ArcCHECK diode array. Each field, excluding those with gantry offsets, was also measured using an Electronic Portal Imager and a MatriXX Evolution 2D ionisation chamber array. 132 plans (858 fields) were delivered, producing 572 measured dose distributions. Measured doses were compared to calculated doses for the no-error plan using Gamma analysis with 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria (1716 analyses). Generally, pass rates decreased with increasing errors and/or stricter gamma criteria. Pass rate variations with detector and plan type were also observed. For a 3%/3 mm gamma criteria, none of the devices could reliably detect 1 mm MLC position errors or 1 degree collimator rotation errors. This work has highlighted the need to adapt QA based on treatment plan type and the need for detector specific assessment criteria to detect clinically significant errors.

Technical Note: Collimator angle optimization for multiple brain metastases in dynamic conformal arc treatment planning

To reduce the exposed area by the multileaf collimator between lesions for single-isocenter dynamic conformal arc (DCA) therapy for stereotactic radiosurgery treatment of multiple brain metastases by optimizing the collimator angle orientation. In particular, this is achieved by the avoidance of collimator angles where multiple lesions are exposed by the same leaf pairs. An algorithm that estimates the quality of an arc by considering the target projections onto the plane perpendicular to the central axis of the arc beam. A penalty proportional to the exposure of healthy tissue between metastases is assigned to each control point and each feasible collimator angle from a discretized set of angles. The algorithm can generate two outputs: the fixed optimal collimator angle over all the control points, or the optimal collimator angle trajectory through all the control points considering the rotation speed of the collimator. The first output is based on explicit enumeration of all collimator angles, and the second one generates the optimal trajectory using dynamic programming to find the globally optimal solution with respect to the objective function cost. The algorithm was validated on eight clinical cases having a different number of cranial metastases: two metastases (n=1), three metastases (n=5), four metastases (n=1), and five metastases (n=1). Plans with optimized fixed collimator angles and plans with optimized dynamic collimator trajectories were compared between each other. When comparing optimal dynamic trajectories to fixed optimal collimator trajectories, the resulting plans demonstrated a total reduction of the exposed area between lesions over the entire beam configuration from 21.7% up to 71.3%; similarly, beam-wise reductions ranging from 5.83% to over 90% have been registered. Collimator angle optimization has the potential to reduce the magnitude of the exposed area between lesions in an efficient way for non-isocentric treatments where multiple lesions are treated simultaneously. Dynamic trajectories are capable of limiting the island blocking problem more than optimal fixed trajectories by exploiting the extra degree of freedom of rotating the multileaf collimator. The algorithm can also lead to time saving during the treatment planning process.

The use of collimator angle optimization and jaw tracking for VMAT-based single-isocenter multiple-target stereotactic radiosurgery for up to six targets in the Varian Eclipse treatment planning system.

PurposeIsland blocking occurs in single‐isocenter multiple‐target (SIMT) stereotactic radiotherapy (SRS) whenever targets share multi‐leaf collimator (MLC) leaf pairs. This study investigated the effect on plan quality and delivery, of reducing island blocking through collimator angle optimization (CAO). In addition, the effect of jaw tracking in this context was also investigated.MethodsFor CAO, an algorithm was created that selects the collimator angle resulting in the lowest level of island blocking, for each beam in any given plan. Then, four volume‐modulated arc therapy (VMAT) SIMT SRS plans each were generated for 10 retrospective patients: two CAO plans, with and without jaw tracking, and two plans with manually selected collimator angles, with and without jaw tracking. Plans were then assessed and compared using typical quality assurance procedures.ResultsThere were no substantial differences between plans with and without CAO. Jaw tracking produced statistically significant reduction in low‐dose level parameters; healthy brain V10% and mean dose were reduced by 9.66% and 15.58%, respectively. However, quantitative values (108 cc for V10% and 0.35 Gy for mean dose) were relatively small in relation to clinical relevance. Though there were no statistically significant changes in plan deliverability, there was a notable trend of plans with jaw tracking having lower gamma analysis pass rates.ConclusionThese findings suggest that CAO has limited benefit in VMAT SIMT SRS of 2–6 targets when using a low‐dose penalty to the healthy brain during plan optimization in Eclipse. As clinical benefits of jaw tracking were found to be minimal and plan deliverability was potentially reduced, a cautious approach would be to exclude jaw tracking in SIMT SRS plans.

A unified approach for optimal dose delivery and trajectory optimization for the treatment of prostate cancer

For a Fluence map optimization problem, we present a unique iterative reweighting algorithm-based method to achieve optimality. The purpose of planning is to determine a dose distribution in such a manner that it should cover the maximum part of the target without affecting the functionality of organ at risk. We suggest a unique methodology to solve dose-volume bounds while maintaining their non-convexity, as compared to earlier approaches that dedicated to convex estimation. The suggested approach is cooperative to competent procedures centered on partial minimization and certainly adjusts to tackle maximum-dose bounds. Fluence mapping is used for the inverse planning which determines the intensity profile of each beam. For the analysis, 09 equally separated beams with dose-volume limits on the organ at risk have used to treat malignancies in the prostate. Cumulative dose-volume histogram is used for the treatment plans quality measurement. We considered 4-different samples from CORT dataset named prostate, Liver, TG119 phantom, and Head & Neck to make a judgment about the generalizability of the performance of the proposed algorithm, and after getting this we finally compared our result with other method using prostate sample to validate our approach. After comparing with other methods centered on dose volume limits we found that in our approach maximum dose can deliver within minimum time across the planned target. For the optimization of trajectory we kept, the radiation delivery rate fixed to its extreme level and employed the independence property of each single leaf pair equally. By making this provision for all total T delivery times, trade-off between distribution time and fluency mapping quality is produced.

Carbon and nitrogen isotopic values in Lithops aucampiae during leaf development

Lithops (Aizoaceae) are succulent plants consisting of a pair of opposite succulent leaves inserted on an extremely short stem. The apical meristem produces a new leaf pair that develops between the older pair, recycling water and metabolites. This peculiar anatomy and growth form make ecophysiological studies quite challenging. Lithops are considered to have CAM metabolism, though experimental evidence is scarce. We followed the changes in carbon and nitrogen isotopic values in mature leaves, young leaves and roots, with the aim of investigating how the use of resources is optimized to achieve survival in extremely arid environments. Two-year-old plants of Lithops aucampiae were grown in pots with no irrigation for six months. Plants were sampled periodically, and isotopic values were recorded in relation to the developmental pattern of the leaves. δ13C ranged from −16.4 to −13.1‰ with leaves showing less negative values than roots. δ15N ranged between −0.8 and 3.9‰ with leaves showing higher values than roots. To the best of our knowledge, this is the first experimental evidence of carbon and nitrogen isotope values in Lithops, the former providing evidence for CAM metabolism.