Carlos Alberto da Silva Ledo

Agronomic and molecular characterization of diploid improved banana genotypes.

An investigation about the genetical diversity among eleven banana diploid genotypes using nine agronomical characteristics and sixteen microsatellite markers was implanted at Embrapa Cassava and Tropical Fruits, Cruz das Almas (BA), Brazil. The generalized distance of Mahalanobis indicated the presence of genetic diversity. The genotypes were grouped into tree clusters. Among the investigated characteristics, the plant height, number of bunchs, number of fruits per bunch and pseudostem exhibited high contribution towards genetic divergence. The average number of alleles per primer was 7.51, with a total of 120 alleles identified. The average similarity among the all diploid was 0.44, range from 0.29 up to 0.60. New parental combinations can be identified with base of the divergence between these diploids, contributing for development of new improved diploids preventing the narrow genetic base and creating new genetic variability for selection.

Agronomic and molecular characterization of gamma ray induced banana (Musa sp.) mutants using a multivariate statistical algorithm

Bananas are tropical fruits grown worldwide playing a key role in market trade and especially used as main food source for low income populations. In Brazil, bananas are mainly consumed in natura, occupying the second largest internal market. Nevertheless, this crop presents low availability of productive commercial varieties with good agronomic characteristics. A strategy undertaken to solve this problem is the development of new cultivars through conventional genetic breeding methods. However, this strategy presents some obstacles such as female sterility and low number of seeds. In order to overcome these shortcomings, use of mutation induction aiming the selection of mutants with desirable agronomic characteristics seems to have great potential for developing new cultivars. The objective of the present work was to evaluate the genetic variability in putative banana ‘Pacovan’ (AAB genome, subgroup Prata Type) mutants submitted to gamma ray irradiation, using a set of agronomical and molecular data (ISSR markers). The distance between the putative ‘Pacovan’ mutants varied from 0.26 to 0.64 with cophenetic correlation coefficient of 0.7669. Four mutants were selected based on best agronomical characteristics and height. This data also shows that there is variability that can be explored after the irradiation of ‘Pacovan’ banana mutants, which can be used in the genetic breeding program of banana aiming to develop short new varieties that also present good agronomic characteristics. This is the first attempt to use combined data in order to evaluate the genetic variability in putative banana mutants.

Genótipos de bananeira em três ciclos na Zona da Mata Mineira

The objective of this work was to evaluate during three cycles the main vegetative characteristics of the genotypes Prata Ana, Grande Naine, Caipira, Nam, Pioneira, FHIA-01, FHIA-18, PV03-44 and SH3640, aiming to incorporate new genotypes to commercial production systems. An experiment was carried out at Zona da Mata Mineira region during three crop cycles, in randomized block design, with nine treatments (genotypes) and three replications (cycles). Height, precocity, number of leaves, resistance to Yellow Sigatoka and plant suckers were evaluated. The variety Grande Naine had the lower height, while Prata Ana, FHIA-01 and SH3640, the larger diameter. The genotypes that presented higher precocity were Pioneira and FHIA-18. The varieties Nam and Caipira presented the highest numbers and precocity of suckers. The genotypes FHIA-01, FHIA-18 and SH3640 were superiors in relation to the characteristics evaluated.

Micropropagation and in vitro conservation of Neoglaziovia variegata (Arr. Cam.) mez, a fiber producing bromeliad from Brazil

Neoglaziovia variegata (Arr. Cam.) Mez is a Bromeliaceae native to the Caatinga, used for fiber extraction in the Northeast Region of Brazil. The antropic activity has place this species among the threatened ones. The objective of the work was to establish an in vitro propagation and conservation of caroa. Seeds were cultivated in MS medium in the presence or absence of light. In vitro germinated seedlings were multiplied in MS medium supplemented with the combinations 0.05 and 0.50 µM NAA and 2.2 and 4.4 µM BAP and KIN. The best percentages of germination were obtained with the seeds incubated in the presence of light. The highest multiplication ratio was obtained for the NAA (0,5 µM) + BAP (4,4 µM) treatment and the number of roots, with NAA (0.5 µM) + KIN (2.2 µM). Plant acclimatization presented differentiated results regarding the substrates tested. The conservation was established.

Análise de crescimento de diferentes genótipos de citros cultivados sob déficit hídrico

Aiming the identification of citrus varieties better adapted to Coastal Table Lands, considering their potential use as rootstocks, the performance of different genotypes for drought tolerance was evaluated, considering their physiological indices related to the growth analyses. The study was carried out in a greenhouse condition of the Embrapa Cassava & Tropical Fruits. Six genotypes were studied: Rangpur lime, Volkamer lemon, Sour orange, and the hybrids HTR - 051, TSK o CTTR - 002 and TSK o CTTR - 017, all from the Citrus Breeding Program of the Embrapa Cassava & Tropical Fruits. Seedlings were grown in Plantmaxâ growing media, irrigated adequately until they showed two pairs of true leaves. Afterward, they were transplanted to containers with the same growing media, but chemically fertilized. Seedlings were irrigated until sampling began. The experimental design was completely randomized under a 6 o 7 factorial, corresponding to six genotypes and seven evaluation sampling dates. The evaluations were carried out for seedlings under irrigation, water deficit, and re-watering. It was evaluated dry matter accumulation (DM), for their different fractions (root and above ground), and leaf area (LA) as the bases for the determination of the physiological indices: leaf area ratio (LAR), net assimilation rate (NAR) and relative growth ratio (RGR). It could be concluded that the hybrid HTR - 051 presented less sensibility to the water deficit, suggesting that it could be indicated as a promissory citrus rootstock for water deficit conditions.

Características morfológicas, físicas e químicas de frutos de populações de umbu-cajazeira no Estado da Bahia

A umbu-cajazeira (Spondias sp.) e uma frutifera que ocorre de forma esparsa em todos os Estados brasileiros localizados na regiao semi-arida nordestina, normalmente em areas submetidas a movimentos antropicos, sendo seus frutos consumidos tanto ao natural como na forma de sucos e polpa. O potencial produtivo dessa especie ainda e desconhecido, desde quando nao se conhece a variabilidade existente principalmente no que diz respeito as caracteristicas do fruto. O trabalho objetivou estudar essa variabilidade em tres populacoes no Estado da Bahia, sendo possivel verificar, mediante a analise de variaveis morfometricas, fisicas e quimicas do fruto, utilizando analise de agrupamento, a existencia de uma consideravel diversidade genetica entre individuos nas areas amostradas. Dentre eles, destacaram-se o acesso Vavazinho, com potencial para o consumo ao natural, e o acesso Campo Grande-5, adequado ao processamento de polpa.

Enraizamento in vitro e aclimatização de genótipos de jenipapeiro (Genipa americana L.)

The rhizogenesis is considered a critical stage, since it determines the plant survival during the acclimatization. Among the determinative factors in the induction and the formation of in vitro roots, is distinguished the genotype and the auxin. The objective of the work was to evaluate the effect of different concentrations of acid 4-indol-3-butirico (IBA) in the in vitro rooting in genotype of Genipa americana L; as well as the process of acclimatization of the plant using different substrate. For the in vitro rooting stage, shoots of 2.0 cm long, proceeding from the culture medium with 6-benzilaminopurina (BAP) in concentrations of 2,22; 8,87; 17,74 and 26,76 µM plus the witness with absence of the BAP, were inoculated in medium MS supplemented with IBA (4.9; 9.8 e 14.7 µM) plus the witness with IBA absence. To the acclimatization process it was used as supporting material washed sand, Plantmax® HT and Ecoterra®. The variables analyzed were: percentage of rooting, number of adventitious roots, and length of the largest root, percentage of survival and height of the plant in the acclimatization phase. The results showed that IBA at 9.8 mM induced greater rooting percentage. The substrate Ecoterra® influenced significantly in the quality of root system and quality of the aerial part.

Índices fisiológicos e crescimento inicial de mamoeiro (Carica papaya L.) em casa de vegetação

No Brasil, a cultura do mamoeiro (Carica papaya L.) e amplamente difundida, destacando-se o sul da Bahia e o norte do Espirito Santo onde se concentra a maior parte dos plantios comerciais. Por ser uma cultura que necessita de renovacao dos pomares de quatro em quatro anos, no maximo, ha uma necessidade constante de renovacao deles, fazendo com que a demanda por novas tecnologias e melhoria na qualidade das mudas cresca, forcando o desenvolvimento de pesquisas na area. A analise de crescimento tem sido usada por pesquisadores, na tentativa de explicar diferencas no crescimento, de ordem genetica ou resultante de modificacoes do ambiente e constitui uma ferramenta eficiente para a identificacao de materiais promissores, alem de identificar caracteristicas que, no crescimento inicial, indiquem possibilidade de aumento no rendimento da planta adulta, favorecendo os trabalhos de melhoramento na busca de materiais mais produtivos. Por isso, objetivou-se avaliar o crescimento inicial de plantas de mamoeiro em casa de vegetacao, por meio de indices fisiologicos, como parâmetros indicativos do rendimento. Assim, instalou-se um experimento no delineamento inteiramente casualizado, utilizando a cultivar Golden e outro com o hibrido Tainung No1. Concluiu-se que os indices fisiologicos; taxa de crescimento absoluto, taxa de crescimento relativo, taxa assimilatoria liquida e razao de area foliar sao ferramentas eficientes para identificar e comparar diferentes materiais geneticos, durante o crescimento inicial de plantas de mamoeiro da cultivar Golden e do hibrido Tainung No1, em casa de vegetacao.

Análise de variância multivariada para os cruzamentos dialélicos

Com este trabalho objetivou-se apresentar a analise de variância multivariada para os cruzamentos dialelicos, com o intuito de fornecer meios mais eficientes para a selecao de genotipos superiores. Entre as metodologias mais comumente utilizadas para analise dialelica, cita-se a proposta por Gardner e Eberhart (1966), por meio da qual sao estimados os efeitos dos genitores e da heterose entre seus hibridos. Essa metodologia, no entanto, e proposta apenas para o caso univariado. O fato e que, para a obtencao de populacoes superiores, os melhoristas necessitam avaliar varios caracteres para melhor inferir sobre a superioridade relativa dos mesmos. Para isso, foi adotado um modelo extendido para um numero k > 1 de variaveis. Inicialmente, foram obtidos, pelo metodo dos quadrados minimos, as expressoes explicitas dos estimadores dos efeitos geneticos desse modelo e de suas respectivas variâncias. Posteriormente, foram obtidas as matrizes de soma de quadrados e produtos relacionados. Finalmente, foram apresentados os testes multivariados para as hipoteses de interesse. A analise de variância multivariada para os cruzamentos dialelicos pode ser realizada para estimar a heterose em varias caracteristicas simultaneamente.

Desenvolvimento e parasitismo de Lysiphlebus testaceipes (Cresson) e Aphidius colemani Viereck (Hymenoptera: Braconidae) em Aphis gossypii Glover (Hemiptera: Aphididae) em duas cultivares de crisântemo

The parasitoids Lysiphlebus testaceipes (Cresson) and Aphidius colemani Viereck play an important role on the regulation of aphid populations on chrysanthemum grown in greenhouses. This study evaluated the interaction of biological control and plant resistance by the development and the parasitism of L. testaceipes and A. colemani on Aphis gossypii Glover. The aphid host was kept on commercial cultivars of chrysanthemum susceptible Yellow Snowdon (YS) and resistant White Reagan (WR). The experiment was carried out in climatic chamber at 22 +/- 1 masculineC, 70 +/- 10% RH, and photophase 12h. Nymphs of 2nd and 3rd instars of A. gossypii attacked only once by the parasitoids were used in the experiment. The development time was 15.0 and 12.9 days for L. testaceipes and 17.0 and 16.3 days for A. colemani kept on A gossypii on cvs. YS and WR, respectively. The parasitoid L. testaceipes showed greater parasitism rate (68.4%) on A. gossypii on cv. YS than on WR (50%), and for A. colemani was not found significative difference on parasitism (46.8 and 35% to YS and WR, respectively). The emergence rates of L. testaceipes and A. colemani were 91.6% and 85.3% on A gossypii reared on YS, and 78.1% and 100% on WR, respectively. The longevity of A colemani and the parasitism rate of L. testaceipes were affected in a negative way by the cv. WR. The results indicated a positive interaction of biological control with parasitoids and the resistant cv. WR on A. gossypii control in protected cultivation.