Clones are a matter of great concern to the software engineering community because of their dual but contradictory impact on software maintenance. While there is strong empirical evidence of the harmful impact of clones on maintenance, a number of studies have also identified positive sides of code cloning during maintenance. Recently, to help determine if clones are beneficial or not during software maintenance, software researchers have been conducting studies that measure source code stability (the likelihood that code will be modified) of cloned code compared to non-cloned code. If the presence of clones in program artifacts (files, classes, methods, variables) causes the artifacts to be more frequently changed (i.e., cloned code is more unstable than non-cloned code), clones are considered harmful. Unfortunately, existing stability studies have resulted in contradictory results and even now there is no concrete answer to the research question "Is cloned or non-cloned code more stable during software maintenance?" The possible reasons behind the contradictory results of the existing studies are that they were conducted on different sets of subject systems with different experimental setups involving different clone detection tools investigating different stability metrics. Also, there are four major types of clones (Type 1: exact; Type 2: syntactically similar; Type 3: with some added, deleted or modified lines; and, Type 4: semantically similar) and none of these studies compared the instability of different types of clones. Focusing on these issues we perform an empirical study implementing seven methodologies that calculate eight stability-related metrics on the same experimental setup to compare the instability of cloned and non-cloned code in the maintenance phase. We investigated the instability of three major types of clones (Type 1, Type 2, and Type 3) from different dimensions. We excluded Type 4 clones from our investigation, because the existing clone detection tools cannot detect Type 4 clones well. According to our in-depth investigation on hundreds of revisions of 16 subject systems covering four different programming languages (Java, C, C#, and Python) using two clone detection tools (NiCad and CCFinder) we found that clones generally exhibit higher instability in the maintenance phase compared to non-cloned code. Specifically, Type 1 and Type 3 clones are more unstable as well as more harmful compared to Type 2 clones. However, although clones are generally more unstable sometimes they exhibit higher stability than non-cloned code. We further investigated the effect of clones on another important aspect of stability: method co-changeability (the degree methods change together). Intuitively, higher method co-changeability is an indication of higher instability of software systems. We found that clones do not have any negative effect on method co-changeability; rather, cloning can be a possible way of minimizing method co-changeability when clones are likely to evolve independently. Thus, clones have both positive and negative effects on software stability. Our empirical studies demonstrate how we can effectively use the positive sides of clones by minimizing their negative impacts.

The cloning of code is controversial as a development practice. Empirical studies on the long-term effects of cloning on software quality and maintainability have produced mixed results. Some studies have found that cloning has a negative impact on code readability, bug propagation, and the presence of cloning may indicate wider problems in software design and management. At the same time, other studies have found that cloned code is less likely to have defects, and thus is arguably more stable, better designed, and better maintained. These results suggest that the effect of cloning on software quality and maintainability may be determinable only on a case-by-case basis, and this only aggravates the challenge of establishing a principled framework of clone management and understanding. This thesis aims to improve the understanding and management of clones within software systems. There are two main contributions. First, we have conducted an empirical study on cloning in one of the major device drivers families of the Linux kernel. Different from many previous empirical studies on cloning, we incorporate the knowledge about the development style, and the architecture of the subject system into our study; our findings address the evolution of clones; we have also found that the presence of cloning is a strong predictor (87\% accuracy) of one aspect of underlying hardware similarity when compared to a vendor-based model (55\% accuracy) and a randomly chosen model (9\% accuracy). The effectiveness of using the presence of cloning to infer high-level similarity suggests a new perspective of using cloning information to assist program comprehension, aspect mining, and software product-line engineering. Second, we have devised a triage-oriented taxonomy of clones to aid developers in prioritizing which kinds of clones are most likely to be problematic and require attention; a preliminary validation of the utility of this taxonomy has been performed against a large open source system. The cloning-based software quality assurance (QA) framework based on our taxonomy adds a new dimension to traditional software QA processes; by exploiting the clone detection results within a guided framework, the developer is able to evaluate which instances of cloning are most likely to require urgent attention.

Two identical or similar code fragments form a clone pair. Previous studies have identified cloning as a risky practice. Therefore, a developer needs to be aware of any clone pairs so as to properly propagate any changes between clones. A clone pair experiences many changes during the creation and maintenance of software systems. A change can either maintain or remove the similarity between clones in a clone pair. If a change maintains the similarity between clones, the clone pair is left in a consistent state. However, if a change makes the clones no longer similar, the clone pair is left in an inconsistent state. The set of states and changes experienced by clone pairs over time form an evolution history known as a clone genealogy. In this thesis, we provide a formal definition of clone genealogies, and perform two case studies to examine clone genealogies. In the first study, we examine clone genealogies to identify fault-prone “patterns” of states and changes. We also build prediction models using clone metrics from one snapshot and compare them to models that include historical evolutionary information about code clones. We examine three long-lived software systems and identify clones using Simian and CCFinder clone detection tools. The results show that there is a relationship between the size of the clone and the time interval between changes and fault-proneness of a clone pair. Additionally, we show that adding evolutionary information increases the precision, recall, and F-Measure of fault prediction models by up to 26%. In our second study, we define 8 types of late propagation and compare them to other forms of clone evolution. Our results not only verify that late propagation is more harmful to software systems, but also establish that some specific cases of late propagations are more harmful than others. Specifically, two cases are most risky: (1) when a clone experiences inconsistent changes and then a re-synchronizing change without any modification to the other clone in a clone pair; and (2) when two clones undergo an inconsistent modification followed by a re-synchronizing change that modifies both the clones in a clone pair. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-01-31 11:39:10.503

Clonal propagation of Eucalyptus spp. and its hybrids allows for competitiveness in the commercial forestry industry through the propagation and preservation of superior/elite genotypes. Vegetative propagation through rooted cuttings is the industry‟s standard and the choice of clones selected for plantations are determined by their rooting ability. However, as many potentially valuable genotypes are recalcitrant to adventitious rooting, micropropagation is the only effective means of propagating them. Micropropagation results in high plantlet yields, achieved primarily through the empirical use of the key plant growth regulators (PGRs) cytokinins and auxins, for shoot and root production, respectively. Their selection for use in vitro is driven by their effects on percent rooting rather than root quality. Little is known regarding the quality of the roots of the plantlets ex vitro, but there is some evidence that they are different from those of seedlings and cuttings. It was therefore hypothesized that the properties of exogenous PGRs and their interaction with other exogenous and endogenous PGRs, influenced root development and subsequent root quality. This was tested in vitro using a good-rooting E. grandis (TAG31) and two poor-rooting E. grandis x nitens hybrid clones (GN155 and NH58). In the former, the auxins supplied during the pre-rooting culture stages (multiplication and elongation) were sufficient for 100% rooting in an auxin-free rooting medium. Different combinations of PGRs in the two pre-rooting stages, followed by rooting without auxins, revealed a direct relationship between the stability of the supplied auxin and the rooting ability of TAG31. Gas chromatographymass spectrometry (GC-MS) analyses indicated that endogenous shoot levels of indole- 3-acetic acid (IAA) influenced graviperception. Also, low IAA content was associated with atypical starch grain accumulation or its absence from root tips (53.1 nmol IAA gˉ¹ DW compared with 325.7 nmol IAA g-¹ DW in gravisensing roots). The specific roles of the natural auxins IAA and IBA on root morphogenesis were then investigated using 2,3,5-triiodobenzoic acid (TIBA; inhibits IAA transport), ρ-chlorophenoxyisobutyric acid (PCIB; inhibits auxin signal transduction), and the auxin antagonist kinetin in the rooting medium, following root induction. After 3 weeks, the mean root diameter was significantly reduced from 552.8μm (control) to 129.2μm (with PCIB) and 278.6μm (with kinetin). TIBA increased root diameter to 833.4μm, decreased Δ root length, increased root vasculature and resulted in agravitropism. Hence, whereas rooting could be induced by IBA, IAA was necessary for the maintenance of vascular integrity and graviperception. This critical role of IAA in root development is of importance as IBA, owing to its higher stability, has been traditionally relied upon for root induction in the majority of micropropagation protocols. The potential of incorporating IAA into the media formulations of in vitro protocols for poor-rooters that do not respond well to IAA was then investigated, using GN155 and NH58. While PCIB in the rooting medium of GN155 completely inhibited rooting, the addition of dihydroxyacetophenone (DHAP), an inhibitor of auxin conjugation, to the rooting medium, did not significantly increase % rooting in the presence of 0.1 mg 1ˉ¹ IBA (i.e. 50% rooting with 2mM DHAP and IBA, compared with 45% with IBA alone). The results suggested that the inability of some eucalypts to induce roots easily in vitro was not due to a deficiency in auxin signal transduction or to auxin conjugation. Instead, rooting was inhibited by an accumulation of kinetin within shoots during the pre-rooting culture stages. The endogenous levels of PGRs in shoots of GN155 and NH58 showed a strong relationship (R² = 0.943) between the shoot kinetin:auxin and shoot rootability. Substituting kinetin with the relatively less stable natural cytokinin trans-zeatin in the elongation stage resulted in a significant increase in % rooting in both clones, from 19% to 45% (GN155) and from 31% to 52% (NH58), with 0.1 mg 1ˉ¹ IAA in the rooting medium. However, omitting all cytokinins from the elongation medium, resulted in over 95% and 75% rooting of shoots of GN155 and NH58, respectively, with 0.1 mg 1ˉ¹ IAA. These results suggest that IAA is a requirement for root development and cannot be substituted by its analogues in certain root developmental events. Hence, IAA should be the preferred auxin for eucalypt micropropagation. As fundamental research, the approach taken in this study circumvents the empirical method used in improving micropropagation protocols. The importance of the properties and the interactions between endogenous and exogenous PGRs in regulating root morphogenesis, and the practical implications of these findings is emphasised. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.

The development of radiata pine (Pinus radiata D. Don.) clones was compared in monoclonal and clonal mixture plots planted in an experiment established at Dalethorpe, Canterbury, New Zealand with ten radiata pine clones in September 1993. Clones were deployed in a randomised complete block plot design with three replications. Each replication contained ten treatments of monoclonal plots and one in which all the clones were intimately mixed in equal proportions. Clones significantly differed in initial morphologies, survival and stem slenderness. Sturdiness and initial heights were found to be the best predictors of initial survivals. The study revealed that mode of deployment did not affect overall productivity, but individual clones exhibited significantly different productivities between modes of deployment. All clones contributed similarly to overall productivity in the monoclonal mode of deployment, whereas the contribution of clones in the clonal mixture mode of deployment was disproportionate. A minority of the clones contributed a majority of overall productivity in the clonal mixture mode of deployment. The inclusion of competition index as an independent variable in a distance-dependent individual tree diameter increment model explained a significant amount of variability in diameter growth. The use of an inverse-squared distance to neighbouring plants in the competition index provided a slightly superior fit to the data compared to one that employed a simple inverse of distance. Addition of genotype information in the competition index further improved the fit of the model. Clones experienced different levels of competition in monoclonal and clonal mixture modes of deployment. Competition in monoclonal plots remained uniform over time, whereas some clones experienced greater competition in clonal mixture plots which led to greater variability in their tree sizes. This study indicated that single tree plot progeny test selections and early selections may miss out some good genotypes that can grow rapidly if deployed monoclonally. Stand level modelling revealed that clones differed significantly in modeled yield patterns and model asymptotes. Clones formed two distinct groups having significantly different yield models. The study also demonstrated that models developed from an initial few years’ data were biased indicators of their relative future performances. Evaluation of effectiveness of the 3-PG hybrid model using parameter values obtained from destructive sampling and species-specific values from different studies revealed that it is possible to calibrate this model for simulating the productivity of clones, and predictions from this model might inform clonal selections at different sites under differing climatic conditions. Destructive sampling at age 5 years revealed that clones significantly differed in foliage and stem biomass. The differences in productivities of clones were mainly due to differences in biomass partitioning and specific leaf areas. Clones significantly differed in dynamic wood stiffness, stem-slenderness, branch diameter, branch index and branch angle at an initial stocking of 1250 stems/ha. Mode of deployment affected stem slenderness, which is sometimes related to stiffness. Although dynamic stiffness was correlated with stem slenderness and stem slenderness exhibited a significant influence on stiffness, clones did not exhibit statistically significant differences in dynamic stiffness. Increasing initial stocking from 833 stems/ha to 2500 stems/ha resulted in a 56 % decrease in branch diameter and a 17 % increase in branch angle. Trees in the monoclonal mode of deployment exhibited greater uniformity with respect to tree size, stem-slenderness, and competition experienced by clones compared to those in the clonal mixture mode of deployment. Susceptibility of one clone to Woolly aphid suggested that greater risks were associated with large scale deployment of susceptible clones in a monoclonal mode of deployment. This study also indicated that if the plants were to be deployed in a monoclonal mode then block plot selections would have greater potential to enhance productivity.

The cloning of code is controversial as a development practice. Empirical studies on the long-term effects of cloning on software quality and maintainability have produced mixed results. Some studies have found that cloning has a negative impact on code readability, bug propagation, and the presence of cloning may indicate wider problems in software design and management. At the same time, other studies have found that cloned code is less likely to have defects, and thus is arguably more stable, better designed, and better maintained. These results suggest that the effect of cloning on software quality and maintainability may be determinable only on a case-by-case basis, and this only aggravates the challenge of establishing a principled framework of clone management and understanding. This thesis aims to improve the understanding and management of clones within software systems. There are two main contributions. First, we have conducted an empirical study on cloning in one of the major device drivers families of the Linux kernel. Different from many previous empirical studies on cloning, we incorporate the knowledge about the development style, and the architecture of the subject system into our study; our findings address the evolution of clones; we have also found that the presence of cloning is a strong predictor (87\% accuracy) of one aspect of underlying hardware similarity when compared to a vendor-based model (55\% accuracy) and a randomly chosen model (9\% accuracy). The effectiveness of using the presence of cloning to infer high-level similarity suggests a new perspective of using cloning information to assist program comprehension, aspect mining, and software product-line engineering. Second, we have devised a triage-oriented taxonomy of clones to aid developers in prioritizing which kinds of clones are most likely to be problematic and require attention; a preliminary validation of the utility of this taxonomy has been performed against a large open source system. The cloning-based software quality assurance (QA) framework based on our taxonomy adds a new dimension to traditional software QA processes; by exploiting the clone detection results within a guided framework, the developer is able to evaluate which instances of cloning are most likely to require urgent attention.

The creation of stable mammalian cell lines for biopharmaceutical production often require several months, and is unfavourable for the rapid production of multiple drug candidates for screening in the early stages of development. Biopharmaceutical production by transient transfection provides a possible alternative of quickly producing these early stage drug candidates. The Epi-CHO transient expression system, which consists of a Chinese hamster ovary (CHO) cell line (CHO-T) expressing the murine polyomavirus Large T-Antigen (LT), emonstrated enhanced transient recombinant protein production. The aim of this study was to prolong transient recombinant protein prod.Jction of the Epi-CHO expression system by creating a CHO cell line expressing both LT and EBNA1 (ECHO-T). The pEBNA1-LT expression vector encoding LT and EBNA1 was constructed and transfected into CHO-K1. A total of 20 clones were isolated from the antibioticresistant pool and screened for the expression of functional LT and EBNA1. PCR analysis showed 16 of the 20 clones was positive for EBNA1 and LT DNA. Of the 16 clones, six were positive for EBNA1 and LT expression by RT-PCR. Detection of LT and EBNA1 by immunofluorescence showed positive staining for the P7-G3 clone. Western blotting suggested the P7-G3 clone was: positive for EBNA1, and clones P3-C7 and P7-E2 were positive for LT. A plasmid replication assay confirmed the expression of functional LT in all six clones. Plasmid maintenance assay confirmed clone P7-G3 as the ECHO-T clones to express functional EBNA1. The P7-G3 clone demonstrated prolonged and sustained transient recombinant protein expression when compared to CHO-T. The P7-G3 clone achieved sustained transient protein expression for 32 days in the absence of selection, the longest currently reported for CHO cells.

Thèse (M.Sc.)--Université Laval, 2003. / Bibliogr.: f. 123-142. Publié aussi en version électronique.

PINTO, Olienaide Ribeiro de Oliveira. Reação de clones comerciais de cajueiro ao oídio. 2016. 117 f. Tese (Doutorado em Agronomia/Fitotecnia)-Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Aline Mendes (alinemendes.ufc@gmail.com) on 2016-08-22T22:37:05Z No. of bitstreams: 1 2016_tese_oropinto.pdf: 12667163 bytes, checksum: 85633b4d490ff9feb067855feed32454 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-08-23T18:27:28Z (GMT) No. of bitstreams: 1 2016_tese_oropinto.pdf: 12667163 bytes, checksum: 85633b4d490ff9feb067855feed32454 (MD5) / Made available in DSpace on 2016-08-23T18:27:28Z (GMT). No. of bitstreams: 1 2016_tese_oropinto.pdf: 12667163 bytes, checksum: 85633b4d490ff9feb067855feed32454 (MD5) Previous issue date: 2016 / Powdery mildew has become one of the main pathogens of cashew plantations, causing damage to leaves, inflorescences, maturis, nuts and stalks. Thus, it is very important research aimed at studying the development of the disease in commercial cultivars cashew in different epidemiological stages of the disease in order to identify resistant cultivars.The objective of this study was to evaluate the reaction of commercial cultivars cashew mildew based on monitoring of severity over time disease, check the morphological difference between resistant and susceptible plant tissues and develop a natural inoculation methodology as an alternative early selection of cashew cultivars. The research was divided into three experiments at Embrapa, the first of which was in the Experimental Field of Pacajus, evaluating the reaction of eleven cultivars to mildew in three production cycles (2012, 2013 and 2014). The second was in the laboratory of electronic microscopy, studying the morphology of the powdery mildew infection process six cultivars (samples of flowers and leaves). The third test was a natural inoculation of powdery mildew method for early selection of cashew cultivars, which used ten cultivars changes with a test Fortress and other Pacajus. In the first and third tests, we evaluated the disease severity scale descriptive notes (0 to 4). In the first, it identified groups of similar cultivars in reaction to powdery mildew, through cluster analysis of three production cycles. BRS 274 cultivars BRS 275, BRS 226 and CCP 1001 were the most resistant, while the BRS 189 and cultivars CCP 06 were the most susceptible. The area under the disease progress curve (AUDPC) showed that there is difference between the cashew cultivars in reaction to powdery mildew during the crop production cycle. In the study under microscopy, it was noted in the inflorescences of cultivars a lot of upright conidiophores, except BRS 253. In the leaves, has been seen mycelium covering their surfaces with appressoria well developed, penetrating the epidermis. In sepals it found that the fungus invests in the Conidiogenesis process. In the third test, the test method was effective for cashew about the reaction of cultivars to powdery mildew on the leaves, and cultivar BRS 274 was the most resistant to powdery mildew for the two sites. In this research the cashew cultivars BRS 274, BRS 226, BRS 275 and CCP in 1001 have been identified as sources of resistance to powdery mildew and can be used in the integrated management of the disease. / O oídio tornou-se um dos principais fitopatógenos dos plantios de cajueiros, causando danos em folhas, inflorescências, maturis, pedúnculos e castanhas. Assim, é de suma importância pesquisas visando estudar o desenvolvimento da doença em clones comerciais de cajueiro nas diferentes fases epidemiológicas da doença, a fim de identificar clones resistentes. O objetivo deste trabalho foi avaliar a reação de clones comerciais de cajueiro ao oídio baseado em monitoramento da severidade da doença ao longo do tempo, verificar a diferença morfológica entre os tecidos de plantas resistentes e suscetíveis e, desenvolver uma metodologia de inoculação natural como alternativa de seleção precoce de clones de cajueiro. A pesquisa foi dividida em três experimentos na Embrapa Agroindústria Tropical, sendo que o primeiro foi no Campo Experimental de Pacajus, avaliando-se a reação de onze clones ao oídio em três ciclos de produção (2012, 2013 e 2014). O segundo foi no laboratório de microscopia eletrônica de varredura, estudando-se a morfologia do processo de infecção do oídio de seis clones (amostras de flores e folhas). O terceiro foi testar uma metodologia de inoculação natural de oídio para seleção precoce de clones de cajueiro, em que se utilizou muda de dez clones, com um ensaio em Fortaleza e outro em Pacajus. No primeiro e terceiro ensaios, avaliou-se a doença por uma escala descritiva de notas de severidade (0 a 4). No primeiro, se identificou grupos de clones similares na reação ao oídio, através da análise de agrupamento dos três ciclos de produção. Os clones BRS 274, BRS 275, BRS 226 e CCP 1001 foram os mais resistentes, enquanto, os clones BRS 189 e CCP 06 foram os mais suscetíveis. A área abaixo da curva de progresso da doença (AACPD) evidenciou que existe diferença entre os clones de cajueiro na reação ao oídio durante os ciclos de produção da cultura. No estudo sob microscopia, notou-se nas inflorescências dos clones uma grande quantidade de conidióforos eretos, exceto, o BRS 253. Nas folhas, foi visto micélio cobrindo suas superfícies, com apressórios bem desenvolvido, penetrando a epiderme. Nas sépalas verificou-se que o fungo investe no processo da conidiogênese. No terceiro ensaio, o método testado foi efetivo para o cajueiro quanto à reação dos clones ao oídio nas folhas, e o clone BRS 274 foi o mais resistente ao oídio para os dois locais. Nessa pesquisa, os clones de cajueiro BRS 274, BRS 226, BRS 275 e CCP 1001 foram identificados como fonte de resistência ao oídio, podendo ser usadas no manejo integrado da doença.

CUNHA NETO, J. Seleção de clones de aceroleira, repetibilidade, correlações e uso de técnicas multivariadas entre caracteres agronômicos e de pós-colheita. 2009. 131 f. Dissertação (Mestrado em Agronomia/Fitotecnia) - Centro de Ciências Agrária, Universidade Federal do Ceará, Fortaleza, 2009. / Submitted by Francisco Lacerda (lacerda@ufc.br) on 2014-07-17T21:04:43Z No. of bitstreams: 1 2009_dis_jcunhaneto.pdf: 1293349 bytes, checksum: 12c776f7e3c071861c35fab19c2683d2 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa(jairo@ufc.br) on 2014-07-21T18:45:26Z (GMT) No. of bitstreams: 1 2009_dis_jcunhaneto.pdf: 1293349 bytes, checksum: 12c776f7e3c071861c35fab19c2683d2 (MD5) / Made available in DSpace on 2014-07-21T18:45:26Z (GMT). No. of bitstreams: 1 2009_dis_jcunhaneto.pdf: 1293349 bytes, checksum: 12c776f7e3c071861c35fab19c2683d2 (MD5) Previous issue date: 2009 / Given the demand for varieties or clones of acerola above Embrapa Tropical Agroindustry developed in the years 1996 to 2007, the program of genetic improvement of aceroleira in order to recommend clones productive, with fruits of excellent quality, but also to avoid genetic homogeneity of commercial plantations. Having this goal in 1996, dies 100 plants were selected by mass selection in an orchard of fruit company of Ceara S/A (FRUCESA). From these matrices was initiated the program to improve the aceroleira at Embrapa Tropical Agroindustry, which was divided into breeding stock and clonal, resulting in 2003 in the launch of four clones recommended for the State of Ceará, the following: BRS 235 (Apodi) , BRS 236 (Cereja), BRS 237 (Roxinha) and BRS 238 (Frutacor). Another result of this study was to obtain 25 clones of aceroleira in progenies of the second round of selection, which were installed in the experimental field of Embrapa Tropical Agroindustry in December 2002 for evaluation during the period of five years, followed by selection the three best clones based on their agronomic and post-harvest. The experiment was installed in the Experimental Field of Paraipaba (CE), under a randomized block design with 25 treatments, three replications and three plants per plot, spaced 4 m x 4 m. From the assessments it was estimated the variability of the clones, as well as the coefficient of repeatability and correlation of the characteristics evaluated. The selection was made after the construction of selection index of Mulamba & Mock, aided by the method of principal components. It was observed that the 25 clones have reduced genetic variability for agronomic traits. The selection of clones, based only on morphological characteristics and production can now present satisfactory results from the second year of evaluation, it was highlighted for clones 79 / 2 (7), 79/10 (9) and 87 / 11 (7) with potential for use in a commercial. It was observed that the method of principal components based on a correlation matrix is presented as the most efficient for the estimation of the coefficient of repeatability. Estimates of the coefficients of repeatability of AP characteristics, DC, weight, TSS and vitamin C, show high regularity in the superiority of individuals from one year to another, and that 5-10 assessments are sufficient to predict the actual level of individuals with certainty of 95%. Based on the correlation coefficients between the characters it follows that the selection of fruits with higher content of vitamin C can be carried out indirectly. From the selection index of Mulamba & Mock was recommended the selection of genotypes 87/11 (7), 79/10 (9) and 91 / 8 (2) by presenting a number of favorable attributes, with potential to be evaluated in large-scale experiments in different regions of the state of Ceará. / Diante da demanda por variedades ou clones de aceroleiras superiores a Embrapa Agroindústria Tropical desenvolveu, nos anos de 1996 a 2007, o programa de melhoramento genético da aceroleira, com o propósito de recomendar clones produtivos, com frutos de excelente qualidade, como também de evitar a homogeneização genética dos plantios comerciais. Diante deste objetivo, em 1996, foram selecionadas 100 plantas matrizes por meio da seleção massal em um pomar da empresa Frutas do Ceará S/A (FRUCESA). A partir dessas matrizes foi iniciado o programa de melhoramento da aceroleira na Embrapa Agroindústria Tropical, o qual foi dividido em melhoramento populacional e clonal, resultando em 2003 no lançamento de quatro clones recomendados para o Estado do Ceará, a seguir: BRS 235 (Apodi), BRS 236 (Cereja), BRS 237 (Roxinha) e BRS 238 (Frutacor). Outro resultado deste trabalho foi à obtenção de 25 clones de aceroleira, em progênies de segundo ciclo de seleção, que foram instalados no campo experimental da Embrapa Agroindústria Tropical, em dezembro de 2002, para avaliação, durante o período de cinco anos, seguida pela seleção dos três melhores clones com base em suas características agronômicas e de pós-colheita. O experimento foi instalado no Campo Experimental de Paraipaba (CE), sob delineamento de blocos ao acaso, com 25 tratamentos, três repetições e três plantas por parcela, no espaçamento de 4 m x 4 m. A partir das avaliações estimou-se a variabilidade dos clones, como também o coeficiente de repetibilidade e correlação das características avaliadas. A seleção foi realizada após a construção do índice de seleção de Mulamba & Mock, auxiliada pelo método das componentes principais. Observou-se que os 25 clones apresentam reduzida variabilidade genética para as características agronômicas. A seleção de clones, com base apenas nas características morfológicas e de produção já pode apresentar resultados satisfatórios a partir do segundo ano de avaliação, tendo-se destaque para os clones 79/2 (7), 79/10 (9) e 87/11 (7) com potencial para serem utilizados em plantio comercial. Observou-se que o método dos componentes principais com base na matriz de correlação se apresenta como o mais eficiente para a estimação do coeficiente de repetibilidade. As estimativas dos coeficientes de repetibilidade das características AP, DC, PESO, SST e vitamina C, demonstram alta regularidade na superioridade dos indivíduos de um ano para outro, e que de 5 a 10 avaliações são suficientes para predizer o valor real dos indivíduos com nível de certeza de 95%. Com base nos coeficientes de correlação entre os caracteres conclui-se que a seleção de frutos com maior conteúdo de vitamina C pode ser realizada de forma indireta. A partir do índice de seleção de Mulamba & Mock foi recomendada a seleção dos genótipos 87/11 (7), 79/10 (9) e 91/8 (2) por apresentarem uma série de atributos favoráveis, com potencial para serem avaliados em experimentos de larga escala em diferentes regiões do Estado do Ceará.