Number Of Leaf Pairs Research Articles

Characterization of Intsia spp. from Indonesia using microsatellite markers

Microsatellite DNA markers are known to have a high level of genetic diversity and can be used for various purposes. These include population genetic analysis, gene flow assessment, pollen distribution, parent analysis, and accurate distinction between types and varieties. Despite the potential application of microsatellite markers, their development process often requires high costs, energy, and time. To overcome the limitations, several studies have proposed the use of cross-species amplification, which has proven to be a cost and time-efficient method for obtaining species-specific DNA markers. Therefore, this study aimed to identify three species of Merbau in Indonesia, namely Intsia bijuga, I. palembanica, and I. acuminata using cross-species amplification. The three species are known to exhibit similarities in all taxonomical characteristics except for minor differences in the number of leaf pairs per twig and the tip shape of the leaflets. These species also have different levels of economic value and conservation status due to variations in the type of wood produced. Several studies have shown that identification errors can affect the economic value of their wood and logging mistakes can lead to a decrease in the genetic diversity. To address the concerns, Intsia bijuga and I. acuminata from Indonesia were selected as test samples for the cross-amplification of microsatellite markers created for I. palembanica. Due to their taxonomical similarities, the diagnostic characteristics of each Intsia species were assessed based on microsatellite markers. Leaf samples were obtained from three species of Intsia that had been verified and identified based on morphological characteristics by taxonomists from the Bogor Botanical Garden Indonesia. In addition, a total of 10 polymorphic I. palembanica microsatellite markers from the previous literature were used in this study. The results showed that the cross-species amplification of microsatellite locus was successful in all markers. Certain alleles were also observed to be shared by the three species of Intsia, while some were specific to a particular species. These specific alleles could also serve as a diagnostics characteristic for Intsia spp. In addition, a set of polymorphic microsatellites showing a successful transfer across species of Intsia could serve as a valuable tool for comparative studies among related taxa species and breeding and conservation programs.

Vermiculite in the initial development of coffee seedlings in different containers

Coffea arabica L. is responsible for 81% of the coffee cultivation area in Brazil and has great economic and social importance in the regions it is cultivated. Producing vigorous seedlings in a short period of time has become an increasing challenge in coffee growing. Thus, the objective of this study was to evaluate the initial development of seedlings produced in bags and polyethylene tubes with different levels of vermiculite. A 2x5 factorial scheme was used; the factors were: two containers: polyethylene bags (containing standard substrate, subsoil and manure (7:3) and tubes (commercial substrate based on pine bark) and addition of vermiculite, at levels 0%, 10%, 20%, 30% and 40%. In each type of substrate, the respective amounts of vermiculite were added. The variables analyzed were shoot height, root length, stem diameter, number of leaf pairs, shoot and root fresh and dry matter. Based on the results obtained, it was observed that the seedlings produced in polyethylene bags showed higher significant averages for all evaluated parameters, showing greater vigor and initial development than seedlings produced in tubes. The seedlings produced in bags responded positively to the increase in vermiculite for all analyzed parameters, whereas those produced in tubes show the opposite behavior.

Rhizobium Grants the Reduction of Phosphate Fertilization during the Production of Coffee Seedlings

The use of bacterial inoculants is an attractive alternative that could reduce the consumption of chemical fertilizers in crops. In the production system of quality coffee seedlings, it is essential to achieve an adequate balance of nutrients that allows for healthy plants that are resistant to subsequent handling. The objective of this work was to evaluate the effect of Rhizobium sp. inoculation on the growth, nutrition and quality of coffee seedlings cultivated with different doses of phosphoric fertilization. Inoculation tests were carried out under nursery conditions using Coffea arabica L. cv. “Isla 5–15” and Coffea canephora Pierre ex Froehner cv. “Robusta” seeds inoculated with the Rhizobium sp. Rpr2 strain. Sixty days after sowing, the hypocotyldonal graft was performed, and the resulting plants were also treated with the bacterial inoculant. Plants were then planted in substrate with different doses of phosphorus (P): 25, 50, 75 and 100%. At seven months of cultivation, variables of growth (plant height, stem diameter, number of leaf pairs, main root length, root volume, dry mass of the aerial part, root and total), phosphoric nutrition (leaf and root P contents) and posture quality index were evaluated. The inoculation stimulated the aerial part (37%), root growth (34%), the quality index of the grafted postures (30%), and phosphorus absorption (42%) and allowed a decrease from 25 to 75% of the mineral fertilizer. For the first time in Cuba, the benefits of rhizobial inoculation on the nutrition and quality of coffee seedlings were demonstrated. The inoculation of grafted coffee seedlings with Rhizobium sp. Rpr2 through the inoculation method proposed in this study can be recommended as a new easy, cost-effective and efficient inoculation approach to obtain additional benefits for coffee growth, improving the absorption of nutritive elements and the quality characteristics of the coffee seedlings.

Solar Irradiance in the emergence and the initial development of Arabica coffee seedlings in the south of Goiás

The photosynthesis is considered the greatest physiological process of growth, being essential to the supply of raw material for the development of plants. This work was developed with the objective of evaluating shading meshes (35%, 50%, 80% light retention mesh and in full sun), in the emergence and development of Arabica coffee seedlings (Acaiá do Cerrado, Catuaí Amarelo and Mundo Novo), with three replications, totaling 36 experimental units. The plot consisted of 4 plants, totaling 144 plants. Initially, the percentage of seedling emergence and the emergence speed index (IVE) were evaluated. At 180 days, the plant height, stem diameter of the seedlings, leaf area index of the first fully expanded pair of leaves, root length and number of leaf pairs were evaluated, as well as dry and fresh root and shoot. It was concluded that the 35% shading mesh was the one that best favored the IVE of coffee seedlings. There was no significant difference between the shading grids and between the cultivars in relation to the percentage of seedling emergence and the initial development of seedlings for any of the characteristics evaluated. The production of coffee seedlings in full sun is not recommended in the southern region of the state of Goiás.

Growth and quality of Handroanthus heptaphyllus (Vell.) Mattos. seedlings as a function of controlled release fertilizer doses

Controlled-release fertilizers are great allies in the production of seedlings. However, there is a lack of studies focusing on the use of these fertilizers in native forest species. This study aimed to evaluate the effect of different doses of controlled release fertilizers (CRF) on the development and quality of seedlings of Handroanthus heptaphyllus (Vell.) Mattos. The experiment was carried out under greenhouse conditions with plastic cover for a period of 150 days. The pots were distributed in randomized blocks, using twenty plants per experimental unit. The treatments consisted of four doses of CFR Osmocote ® (0, 4.1, 8.2 and 12.3 g dm -3 ) in the formulation NPK 15-09-12, with four replications. The following variables were evaluated: seedling height (H), stem diameter (SD), root length (RL), number of leaf pairs (NLP), leaf area (LA), shoot dry mass (SDM), root dry mass (RDM), total dry mass (TDM), H/SD ratio, Dickson's quality index (DQI) and relative chlorophyll content (SPAD). All evaluated parameters responded significantly to the increasing doses of the CRF. The best responses were found for the doses between 8.5 to 9.5 g dm -3 , considering the evaluated experimental conditions.

BIOLOGICAL CONTROL: ISOLATED AND IN MIXTURES AND GENETIC CONTROL OF Meloidogyne exigua IN COFFE

<em>Meloidogyne exigua</em> is one of the most found species of nematodes in coffee plantations in the Brazilian Cerrado. Thus, the objective of the present study was to evaluate the efficiency of biological agents on two coffee cultivars. The experiment was carried out in a greenhouse using a completely randomized design. The treatments were arranged in a 2x3 factorial scheme, using repeated measures (two cultivars, 3 nematicides, and 2 additional controls), and were composed of two genotypes (Mundo Novo IAC 376-4 and IPR-100), three biological nematicides (B. methylotrophicus, B. subitilis, and T. asperellum), and two treatments including the three nematicides together, totaling 8 treatments and 2 controls, with 6 replicates each. The plants were inoculated with 3,780 eggs and J2s of the respective nematode. Throughout 150 days, the following variables were evaluated monthly: plant height, stem diameter, number of leaf pairs, and chlorophyll contents. At the end of this period (DAI), the reproductive factor (RF), egg mass and gall index were analyzed. About FR, the results were lower (<1) when using the cultivar IPR-100 when compared to the Mundo Novo genotype, denoting adequate genetic control. On the other hand, in the treatments with the susceptible genotype, high FRs were verified, ranging from 2.64 to 5.68 in the control. It was concluded that the bacterial mixtures were efficient in the control, and B.<em> methylotrophicus</em> contributed to higher plant height in the IPR 100 genotype.

Growth and Quality of Inga heterophylla Willd Seedlings According to the Slow Release Fertilizer

Slow release fertilizers have become an alternative for better efficiency in substrate fertilization for seedlings production, however, there are not many studies approaching the use of such fertilizers in the production of native forest species seedlings. This work aimed to evaluate the effect of different doses of a slow release fertilizer (SRF) on the development and quality of the Inga heterophylla seedlings. The experiment was conducted in a vivarium with 50% of shade for a 150-day period. Randomized blocks were the chosen experimental design, constituted of four treatments and four replications, with twenty plants per experimental unit. The treatments were four doses of Osmocote® FLL (0, 4.1, 8.2 and 12.3 g dm-3) in NPK 15-09-12 formulation, with evaluated variables being the height of the seedling (H), collar diameter (CD), number of leaf pairs (NLP), leaf area (LA), aerial part dry mass (APDM), root dry mass, total dry mass (TDM) and Dickson quality index (DQI). All the evaluated parameters responded significantly to the SRF doses and fit the positive quadratic polynomial model. For all of the analyzed variables, results show that the best averages were obtained by using the doses between 5.7 and 6.5 g dm-3, but due to the quadratic response they presented a decrease in the mean values after doses which were superior to the maximum performance point of each characteristic.

Correlations between Eucalyptus Clonal Cutting Quality and Performance after Planting

ABSTRACT This study assessed correlations of different characteristics of cuttings in the nursery of three hybrid clones of Eucalyptus grandis × Eucalyptus urophylla and growth in height after planting. The characteristic that presented greatest correlation with the initial growth was the canopy height and cutting height ratio. At 12 and 24 months in the field, the stem diameter was more important. The parameters assessed in the nursery that correlated positively with growth in the field at three and six months after planting were height, number of leaf pairs, number of root deformations and clod length. At 12 and 24 months the parameters that correlated negatively were diameter, number of leaf pairs and the number of root deformations. Despite presenting significant correlation, root deformations did not interfere in the initial growth of the plants under high rainfall conditions, but the effects became harmful over time resulting in a reduction in plant growth.

Caracteres morfológicos de cafeeiro de porte baixo no primeiro ano de formação em Jaboticabal-SP

Brazil is a world leader in coffee production due to the its diversity of soil and climatic conditions. The juvenile pre-selection of the coffee tree, selecting cultivars that have desirable characteristics correlated with productivity, can help in choosing the appropriate cultivar for each environment. Therefore, the objective of this study was to evaluate the growth and morphological attributes of coffee cultivars of small size in the first year of formation under edaphoclimatic conditions in Jaboticabal-SP. The experimental design was in randomized blocks, with eighteen cultivars and four replications. Plant height and stem diameter were measured at 60, 120, 180, 240 and 300 days after planting. The crown diameter, the height and length of the first plagiotropic branch and the number of leaf pairs were evaluated at 12 months after planting. The cultivars Catuai Amarelo IAC 62 and Catucai 2SL obtained higher plant heights. The largest stem diameters were observed in the cultivars IAC Ouro Amarelo, Obata IAC 1669-20, Oeiras MG 6851, Pau Brasil MG1, Tupi IAC 125 and Catuai Amarelo IAC 62. The crown diameter was higher in the cultivars IAC Ouro Amarelo, Catucai 2SL, Sabia, Catuai Amarelo IAC 62, Sacramento MG1, Pau- Brasil MG1, Tupi IAC 125 and Tupi IAC 1669-33. The cultivars Oeiras MG 6851, Catuai Vermelho IAC 99, Catuai 2SL and Catuai Amarelo IAC 62 showed the highest heights of the first plagiotropic branch. The length of the plagiotropic branch and the number of pairs of leaves per branch, variables that contribute to productivity, did not differ among cultivars.

Efficacy of boron and salicylic acid on quality production of sim carnation (Dianthus caryophyllus)

Flower production is an increasing activity of world’s agriculture. Carnation is one of the most important cut flower of the world which ranks only next to rose. It has been extensively cultivated to be used as cut flower because of its excellent keeping quality. The present study is therefore designed with the aim of improving the quality of Sim carnation by applying Boron (0, 5ppm, 10ppm, 15ppm, 20ppm) and Salicylic acid (0,1mM, 2mM, 3mM and 4mM). Different growth and flowering traits which include plant height, number of leaf pairs, intermodal distance, leaf area, leaf chlorophyll content, days to flower emergence, number of flowers/plant, diameter of flower, stalk length and girth, duration of flowering and dry matter content of plants was studied in the experiment. The results reveal that foliar application of boron and salicylic acid has pronounced effect on growth and quality parameters of carnation. Among all the treatment SA @ 3mM exhibited best results and among doses of boron @ 15ppm showed good results.

Morphophysiological characteristics of (Coffea arabica L.) in different arrangements: lessons from a 3d virtual plant approach

3D vegetative structural and functional models are useful in simulations of ecophysiological and biophysical processes. The main objective of this study was to model a 3D Coffea arabica L. structure. The specific aim was to use 3D mock-ups for analysis of vertical leaf and berry distribution and light interception in coffee crops cultivated in different planting densities and arrangements. The mock-ups were built after abstraction and codification by VPlants, based on morphological measurements (orthotropic shoot height and its number of internodes; positions of second to fourth branching order plagiotropics; internode number on first to fourth branching order plagiotropics number of leaf pairs), and several hypotheses. Mock-ups were visualized in PlantGLViewer, while Silhouette to Total Area Ratio (STAR), leaf area (LA) and berry distribution were processed in VegeSTAR. Planting arrangements influenced STAR when the plants were grown in a low density (6,000 plants ha-1). Plant density had a significant effect on the number of berries in square arrangements. The higher layers were occupied by first order foliage and few berries, allowing more light to pass to the lower canopy layers. Berries were abundant in the first and second order plagiotropic branches, in the highest and middle layers. Light distribution was more uniform than leaf area distribution, indicative of a disperse foliage and efficient space occupation. STAR correlated strongly with berry number, especially in the upper, less shaded canopy layers, where flower induction was the most intense.

Influences of wind and sandblasting on the endangered blowout penstemon

Blowout penstemon Penstemon haydenii is a federally endangered species growing only in areas with active wind erosion in sand dunes of the central United States. This early seral spe- cies declines as the blowout habitat stabilizes, allowing later seral species to increase. Blowout pen- stemon populations and plant size declined in the 1990s when precipitation was higher than normal, resulting in reduced sand movement. We conducted a greenhouse experiment to determine whether blowing sand influenced vigor and persistence of blowout penstemon seedlings. Treatments were wind, sandblasting, wind with sandblasting, and a control. The wind treatment was a constant 14 km h -1 from electric fans for 18 h daily. Sand was applied at 96 km h -1 weekly for 10 min to individual plants for the sandblasting treatment, and the wind with sandblasting treatment was a combination of both. Number of leaf pairs, height, and stem diameter were measured biweekly. Biomass was determined at the conclusion of each experiment. Both wind and sandblasting affected plant growth. The combination of wind with sandblasting increased plant height and stem diameter in Year 1, and stem diameter and shoot biomass in Year 2. This study supports field observations that blowout pen- stemon has a positive thigmomorphogenic response to wind and sandblasting. Less sand movement is associated with wet soils. Therefore, loss of mechanical stimuli could have been one of the reasons for population decline in the 1990s. Disturbance may be necessary to maintain the blowout habitat and provide an important stimulus to the blowout penstemon plants.

Optimizing leaf widths for a multileaf collimator

The multileaf collimator (MLC) is becoming a standard accessory of modern linac in shaping radiation fields. However, for a given target (projection), the radiation field shaped by an MLC has a stepwise boundary and is not identical to the desired field that exactly conforms to the target. That means there are always under-blocked and/or over-blocked areas. The total area of discrepancy depends on MLC leaf widths. The purpose of this study is to develop an optimization model for determining leaf widths so that the total area of discrepancy between MLC-shaped fields and the desired ones can be minimized. The optimization model regards leaf widths as variables, the total area of discrepancy between MLC-shaped fields and the desired fields as an objective function, and the total width of all leaves as a constraint. A problem described by the model is solved with the hybrid of a simulated annealing technique (ASA, Lester Ingber, 1993) and a gradient technique (DONLP2, P Spellucci, 2001). The performance of the optimization model was evaluated on 634 target fields continuously selected from the patient database of a treatment planning system. The lengths of these fields ranged from 3.9 to 38.7 cm and had an average of 15.3 cm. The total area of discrepancy was compared between an MLC with optimal leaf widths and a conventional MLC with the same number of leaf pairs. Optimal leaf widths were obtained for an MLC with total leaf pairs of 28, 40 and 60, respectively, which corresponded to three types of conventional MLCs. The optimal leaf width first decreases slightly and then nonlinearly increases with the distance away from the central line. Compared with the MLC with conventional leaf width arrangement, the MLCs with optimal leaf width arrangement reduced the total area of discrepancy by 11.1%, 28.6% and 25.0%, respectively. Optimizing leaf widths can either improve the conformity of MLC-shaped fields to the treatment targets when the number of leaf pairs does not change, or reduce the number of leaf pairs without sacrifice of field conformity.

Annual growth ofCassiope tetragonaas a proxy for Arctic climate: developing correlative and experimental transfer functions to reconstruct past summer temperature on a millennial time scale

Annual growth of the polar evergreen shrub Cassiope tetragona on Svalbard was evaluated as a proxy for Arctic summer temperatures. Transfer functions were derived from temperature-growth correlations of shoots and from a temperature-growth response, obtained from experimental warming using open top chambers (OTC) in high Arctic tundra vegetation at Isdammen approximately 1.5km southeast of Longyearbyen, Svalbard (781N, 15E) and in Longyeardalen, 3km west of Isdammen from 2004 to 2006. Air temperatures, monitored throughout the summer months, were 1.31C higher inside the OTCs than in the control plots. Annual stem growth was measured by tagging stems and leaves, and in the lab with shoots harvested from OTCs and control plots. Annual growth parameters assessed were leaf production, sum of length and weight of individual leaves, and stem length increment derived from leaf scar distances and the distances between wintermarksepta in the stem. Wintermarksepta are formed at the end of the summer growth period when the pith is narrowing and consist of dense and dark tissue (Fig. 1b). The variation of annual growth in a 34-year site chronology (based on Cassiope shoots from the surroundings of the OTCs and control plots) correlated strongly with the mean summer temperature on Svalbard. The number of leaf pairs, leaf length and stem length also increased in the OTC warmed plots in the second and third year of warming. Transfer functions were derived from the temperature-annual growth correlations from a single shoot from Longyeardalen, from the cross-dated Isdammen site chronology and from the growth response to experimental warming. Based on leaf scar distances and distances between wintermarksepta of well-preserved subfossil shoots in arctic tundra soil, annual stem length increase was assessed for the layers of a soil core collected at the Isdammen site. Based on the derived transfer functions summer temperature of the period relating to the 15cm deep tundra soil core layer, radiocarbon dated at 4230 � 40 BP, may have been 3.01C lower than the present-day 6.21C value. These results indicate that the transfer functions can be used to reconstruct past temperatures, beyond the time range of instrumental temperature and ice core records of Svalbard.

Qualidade de mudas de eucalipto produzidas sob diferentes lâminas de irrigação e dois tipos de substrato

Este trabalho teve por objetivo avaliar lâminas de irrigação na produção de mudas de Eucalyptus grandis, produzidas em dois substratos comerciais à base de cascas de árvores (CPV e CATV). O experimento foi conduzido na Camará - Mudas Florestais, em Ibaté, SP, na estação inverno/primavera/2003, constituindo-se de um delineamento de blocos ao acaso com quatro repetições, sendo cinco lâminas de irrigação diárias (6, 8, 10, 12 e 14 mm), aplicadas através de uma barra de irrigação em diferentes horários (10, 13 e 16 h). Aos 108 dias após a aplicação foram realizadas avaliações da altura de parte aérea, diâmetro de colo, relação altura da parte aérea/diâmetro de colo, número de pares de folhas, matéria seca da parte aérea e das raízes e área foliar. Com relação às características morfológicas, verificou-se a influência das lâminas em todas as variáveis. Dessa maneira, concluiu-se que as lâminas de irrigação de 12 e de 14 mm dia-1 foram as que mais contribuíram para o desenvolvimento das mudas, com qualidade ótima aos 108 dias após a semeadura.

SU-FF-T-332: Optimizing Leaf Width for Multileaf Collimator

Purpose: The multileaf collimator(MLC) has been a standard device for shaping radiation fields. However, the shaped field has stepwise boundary, and can not exactly conform to a treatment target. That means there is always under‐blocked and (or) over‐blocked areas. The total area discrepancy depends on MLC leaf width. The purpose of this study is to minimize the total area discrepancy through optimizing the width of each individual leaf under the assumption that the total number of leaves and the total width of all leaves remain the same. Method and Materials: A program was developed to realize the optimization algorithm. Its flow is like this: a). read data of target shapes; b). initialize leaf widths; c). calculate the total area discrepancy; d). randomly change leaf widths and judge whether to accept the change with simulating annealing technique; e). repeat step d till the iteration process is converged. The algorithm performance was preliminarily evaluated. 113 targets from different treatment sites were randomly selected from the patient data base of our TPS. The target width ranged from 6.8cm to 31.2cm, and had the average of 16.6cm. Results: We obtained the data for a MLC when the total number of leaf pairs was 5, 7, and 13, respectively. The data show that the optimal leaf width super‐linearly increases with the distance away from the central axis. Compared against the MLC with equal leaf width, the MLC with optimal leaf width reduced the total area discrepancy by 25.9%, 28.5%, and 31.4%, respectively. We are collecting data for MLC with more leaf pairs, and investigating the influence of number of targets on optimal leaf width. Conclusions: Optimizing leaf width significantly improves the conformity of MLC shape to target.

SU‐FF‐T‐98: Application of DAVID, a Multi‐Wire Ionisation Chamber for in Vivo‐Verification of IMRT and Conformal Dose Distributions

Purpose: In this work we present first clinical results obtained with the DAVID chamber. Methods and Material: The DAVID system (PTW Freiburg, Germany) is a flat, translucent multi‐wire ionization chamber for daily in‐vivo verification of IMRT beams. It is placed in the accessory holder of the linear accelerator. Each detection wire of the chamber is positioned exactly in the projection line of two opposing leafs of the MLC. The signal of each detection wire is proportional to the line integral of the ionization density along this wire, therefore it is directly proportional to the opening of the associated leaf pair. The number of measurement channels equals the number of leaf pairs. The sum of all wire signals is a measure of the dose‐area product of the transmitted photon beam and of the total radiant energy administered to the patient. Results: After a successful dosimetric verification of an IMRT plan, the values measured by the DAVID system are stored as reference values. During daily treatment the signals are re‐measured and compared to the reference values. In case of a deviation beyond a threshold a warning occurs. Because the DAVID system operates as an ionization chamber, disadvantages which might be observed in other devices, such as aging, are not to be expected. Furthermore, the influences on the beam characteristics are negligible. Conclusion: Clinical examples demonstrate that the DAVID system is a relevant tool to improve the reliability of IMRT treatments. Conflict of Interest: The DAVID system was developed in cooperation with PTW‐Freiburg, Germany.

TU‐C‐T‐6E‐09: The DAVID System — a Device for In‐Vivo Verification of IMRT and Conformal Irradiation Techniques

Purpose: While dosimetric plan verification ensures consistency between planned and measured dose distributions in the pretreatment phase, a daily in‐vivo verification of the beam profiles by a radiation detector positioned at the entrance side of the patient has not been clinically available so far. In this work we present the DAVID system which is able to perform a daily in‐vivo verification of IMRT beams in front of the patient during the treatment. Method and Materials: The DAVID system is a flat, translucent multi‐wire ionization chamber. It is placed in the accessory holder of the linear accelerator. Each detection wire of the chamber is positioned exactly in the projection line of two opposing leafs of the MLC. The measurement signal of each detection wire is directly proportional to the opening of the leaf pair. Therefore the number of measurement channels equals the number of leaf pairs. After a successful dosimetric verification of an IMRT plan, the values measured by the DAVID system are stored as reference values. During daily treatment the signals are re‐measured and compared to the reference values. In case of a deviation beyond a threshold a warning occurs. Results: The error detection capability for a 1 cm × 1 cm field is a leaf position error of less than 0.5 mm. The inherent limit due to electronic noise of the chamber is 1mm for a 20 cm × 20 cm field (all values related to the isocenter). Conclusion: Clinical examples demonstrate that the DAVID system is a relevant tool to improve the reliability of IMRT treatments. Because the DAVID system operates as an ionization chamber, disadvantages which might be observed in other devices, such as aging, are not to be expected. Conflict of Interest: This work was performed in collaboration with PTW‐Freiburg Dr. Pychlau GmbH, Freiburg, Germany.

An automatic CT-guided adaptive radiation therapy technique by online modification of multileaf collimator leaf positions for prostate cancer

To propose and evaluate online adaptive radiation therapy (ART) using in-room computed tomography (CT) imaging that detects changes in the target position and shape of the prostate and seminal vesicles (SVs) and then automatically modifies the multileaf collimator (MLC) leaf pairs in a slice-by-slice fashion. For intensity-modulated radiation therapy (IMRT) using a coplanar beam arrangement, each MLC leaf pair projects onto a specific anatomic slice. The proposed strategy assumes that shape deformation is a function of only the superior-inferior (SI) position. That is, there is no shape change within a CT slice, but each slice can be displaced in the anteroposterior (AP) or right-left (RL) direction relative to adjacent slices. First, global shifts (in SI, AP, and RL directions) were calculated by three-dimensional (3D) registration of the bulk of the prostate in the treatment planning CT images with the daily CT images taken immediately before treatment. Local shifts in the AP direction were then found using slice-by-slice registration, in which the CT slices were individually registered. The translational shift within a slice could then be projected to a translational shift in the position of the corresponding MLC leaf pair for each treatment segment for each gantry angle. Global shifts in the SI direction were accounted for by moving the open portal superiorly or inferiorly by an integral number of leaf pairs. The proposed slice-by-slice registration technique was tested by using daily CT images from 46 CT image sets (23 each from 2 patients) taken before the standard delivery of IMRT for prostate cancer. A dosimetric evaluation was carried out by using an 8-field IMRT plan. The shifts and shape change of the prostate and SVs could be separated into 3D global shifts in the RL, AP, and SI directions, plus local shifts in the AP direction, which were different for each CT slice. The MLC leaf positions were successfully modified to compensate for these global shifts and local shape variations. The ART method improved geometric coverage of the prostate and SVs compared with the couch-shift method, particularly for the superior part of the prostate and all the SVs, for which the interfraction shape change was the largest. The dosimetric comparison showed that the ART method covered the target better and reduced the rectal dose more than a simple couch-translation method. ART corrected for interfraction changes in the position and shape of the prostate and SVs and gave dose distributions that were considerably closer to the planned dose distributions than could be achieved with simple alignment strategies that neglect shape change. The ART proposed in this investigation requires neither contouring of the daily CT images nor extensive calculations; therefore, it may prove to be an effective and clinically practical solution to the problem of interfraction shape changes.

A CONCEPTUAL DYNAMIC MODEL FOR EXTERNAL QUALITY IN KALANCHOE

Modelling quality in pot plants is still a weak feature in crop modelling research. This work aims at building a conceptual dynamic model for external quality (plant height and number of flower heads) in Kalanchoe blossfeldiana. Four experiments were conducted to quantify the effects of temperature and spacing schedules at two different planting dates. Five constant temperatures (18, 20, 22, 24 and 26°C) and nine spacing schedules, resulting from combinations of spacing at a given leaf area index (LAI: 1.6, 2, 3, 4 and 4.4) into a final plant density (31.1, 34.6, 43.4, 52.0 and 55.6 plants m-2) were studied. Stem length was modelled as the number of internodes (same as number of leaf pairs) times the average internode length. Plant height results from the stem length plus the uppermost pedicel length. The spacing schedules did not affect plant height, but total aerial dry mass (TDM, g plant-1), leaf area and number of flower heads were increased at earlier and wider spacing. In contrast, temperature had a significant effect on the average internode length (internode elongation rate linearly increased with temperature) and on the generative length (optimum response to temperature). However, internode appearance rate was not affected by temperature. Number of flower heads showed a positive linear relationship with TDM. Therefore, by simulating TDM the number of flower heads can be predicted. TDM was simulated based on the intercepted photosynthetic active radiation and light use efficiency. The reaction time showed a quadratic response to temperature, with a maximum rate of progress to flower at 23°C (10 days delay at 18°C). These modules need to be validated to form the basis of a year-round decision support system for Kalanchoe.