Selection of morphoagronomic descriptors for the characterization of accessions of cassava of the Eastern Brazilian Amazon.

The aim of this study was to select morphoagronomic descriptors to characterize cassava accessions representative of Eastern Brazilian Amazonia. It was characterized 262 accessions using 21 qualitative descriptors. The multiple-correspondence analysis (MCA) technique was applied using the criteria: contribution of the descriptor in the last factorial axis of analysis in successive cycles (SMCA); reverse order of the descriptor's contribution in the last factorial axis of analysis with all descriptors ('O'´p') of Jolliffe's method; mean of the contribution orders of the descriptor in the first three factorial axes in the analysis with all descriptors ('Os') together with ('O'´p'); and order of contribution of weighted mean in the first three factorial axes in the analysis of all descriptors ('Oz'). The dissimilarity coefficient was measured by the method of multicategorical variables. The correlation among the matrix generated with all descriptors and matrices based on each criteria varied (r = 0.21, r = 0.97, r = 0.98, r = 0.13 for SMCA, 'Os', 'Oz' and 'O'´p', respectively). The least informative descriptors were discarded independently and according to both 'Os' and 'Oz' criteria. Thirteen descriptors were capable to discriminate the accessions and to represent the morphological variability of accessions sampled in Brazilian Eastern Amazonia: color of apical leaves, petiole color, color of stem exterior, external color of storage root, color of stem cortex, color of root pulp, texture of root epidermis, color of leaf vein, color of stem epidermis, color of end branches of adult plant, branching habit, root shape, and constriction of root.

Genetic dissimilarity and selection of putative mutants of Terra Maranhão plantain cultivar using the Ward-MLM strategy.

The objective of this study was to evaluate genetic variability and select putative mutants of Terra Maranhão plantain cultivar (AAB genome) subjected to gamma radiation based on agronomic data and inter simple sequence repeat molecular marker profiles using the Ward-MLM strategy. A total of 233 irradiated plants and 41 controls were assessed. The agronomic and molecular data were subjected to the Ward-MLM statistical algorithm in the SAS program. Cluster analysis was performed by the average distance method (UPGMA), based on the distance matrix of the Gower algorithm, and the cophenetic correlation coefficient calculated using the R software. The distance between the putative mutants ranged from 0.321 to 0.524, with an average distance of 0.426, and a cophenetic correlation coefficient of 0.79. Three putative mutants, which were selected based on the best agronomic traits and low height, will undergo further evaluation in the next stages of the banana breeding program at Embrapa. These results describe the first attempt of using combined data of Terra Maranhão plantain cultivar for the purpose of selecting mutants and assessing genetic variability.

Genetic fidelity and variability of micropropagated cassava plants (Manihot esculenta Crantz) evaluated using ISSR markers.

Molecular markers are efficient for assessing the genetic fidelity of various species of plants after in vitro culture. In this study, we evaluated the genetic fidelity and variability of micropropagated cassava plants (Manihot esculenta Crantz) using inter-simple sequence repeat markers. Twenty-two cassava accessions from the Embrapa Cassava & Fruits Germplasm Bank were used. For each accession, DNA was extracted from a plant maintained in the field and from 3 plants grown in vitro. For DNA amplification, 27 inter-simple sequence repeat primers were used, of which 24 generated 175 bands; 100 of those bands were polymorphic and were used to study genetic variability among accessions of cassava plants maintained in the field. Based on the genetic distance matrix calculated using the arithmetic complement of the Jaccard's index, genotypes were clustered using the unweighted pair group method using arithmetic averages. The number of bands per primer was 2-13, with an average of 7.3. For most micropropagated accessions, the fidelity study showed no genetic variation between plants of the same accessions maintained in the field and those maintained in vitro, confirming the high genetic fidelity of the micropropagated plants. However, genetic variability was observed among different accessions grown in the field, and clustering based on the dissimilarity matrix revealed 7 groups. Inter-simple sequence repeat markers were efficient for detecting the genetic homogeneity of cassava plants derived from meristem culture, demonstrating the reliability of this propagation system.

Selection of putative Terra Maranhão plantain cultivar mutants obtained by gamma radiation.

The aim of this study was to select putative Terra Maranhão plantain cultivar mutants obtained by gamma radiation, with good agronomic traits and short height. A total of 315 buds were irradiated in vitro with gamma rays in doses of 20 Gy and were subcultivated and evaluated in the field over 2 production cycles. The clones were evaluated to select the best 10% of the plants. Cultivation was undertaken at a spacing of 3 x 4 m, and fertilization was carried out according to the technical recommendations for the crop. A total of 111 irradiated plants and 41 controls were evaluated in the field. Among the irradiated plants selected, genotypes that exhibited reduced height were observed. The genotypes Irra 04, Irra 13, Irra 19, and Irra 21 exhibited a height of 3.6 m, which was below the mean value of the controls selected. Other irradiated genotypes selected such as Irra 14 and Irra 16, with a height of 3.65 m, are promising because, in addition to reduced height, they exhibited good bunch weight and shorter period to flowering in relation to the mean value of the controls, which is a significant factor for the next stages in breeding. These results confirm the possibility of inducing mutations in Terra type banana plants to obtain desirable agronomic traits and short height.

Descriptor selection for banana accessions based on univariate and multivariate analysis.

Our objective was to establish a minimum number of morphological descriptors for the characterization of banana germplasm and evaluate the efficiency of removal of redundant characters, based on univariate and multivariate statistical analyses. Phenotypic characterization was made of 77 accessions from Bahia, Brazil, using 92 descriptors. The selection of the descriptors was carried out by principal components analysis (quantitative) and by entropy (multi-category). Efficiency of elimination was analyzed by a comparative study between the clusters formed, taking into consideration all 92 descriptors and smaller groups. The selected descriptors were analyzed with the Ward-MLM procedure and a combined matrix formed by the Gower algorithm. We were able to reduce the number of descriptors used for characterizing the banana germplasm (42%). The correlation between the matrices considering the 92 descriptors and the selected ones was 0.82, showing that the reduction in the number of descriptors did not influence estimation of genetic variability between the banana accessions. We conclude that removing these descriptors caused no loss of information, considering the groups formed from pre-established criteria, including subgroup/subspecies.

Genetic dissimilarity of putative gamma-ray-induced 'Preciosa-AAAB-Pome type' banana (Musa sp) mutants based on multivariate statistical analysis.

Bananas are among the most important fruit crops worldwide, being cultivated in more than 120 countries, mainly by small-scale producers. However, short-stature high-yielding bananas presenting good agronomic characteristics are hard to find. Consequently, wind continues to damage a great number of plantations each year, leading to lodging of plants and bunch loss. Development of new cultivars through conventional genetic breeding methods is hindered by female sterility and the low number of seeds. Mutation induction seems to have great potential for the development of new cultivars. We evaluated genetic dissimilarity among putative 'Preciosa' banana mutants generated by gamma-ray irradiation, using morphoagronomic characteristics and ISSR markers. The genetic distances between the putative 'Preciosa' mutants varied from 0.21 to 0.66, with a cophenetic correlation coefficient of 0.8064. We found good variability after irradiation of 'Preciosa' bananas; this procedure could be useful for banana breeding programs aimed at developing short-stature varieties with good agronomic characteristics.

Longevidade pós-colheita de alpínia [Alpinia purpurata (Vieill.) K. Schum.] tratada com soluções de sacarose e extratos aquosos naturais / Postharvest longevity of red ginger [Alpinia purpurata (Vieill.) K. Schum.] treated with sucrose solutions and natural water extracts

A alpínia (Alpinia purpurata) é uma planta tropical encontrada em diversas regiões do Brasil com excelente potencial para a comercialização como flor de corte. Entretanto, a senescência das hastes pela exaustão da sacarose é um dos principais fatores que afetam a durabilidade comercial, sendo suprimida através da adição de sacarose nas soluções de pulsing. O presente trabalho objetivou avaliar o efeito de extratos aquosos de estévia (Stevia rebaudiana), anis estrelado (Illicium verum) e sacarose em solução de pulsing na manutenção da qualidade pós-colheita de inflorescências de alpínia. Hastes florais uniformizadas em tamanho foram submetidas à solução de pulsing, por 12 horas, nas concentrações de 0,5; 1,0; 2,0 e 3,0 por cento, tendo água destilada como controle. A melhor qualidade comercial das inflorescências foi obtida quando as hastes foram colocadas em pulsing em extratos de anis estrelado e estévia 1 por cento e em solução de sacarose 2 por cento, não apresentando diferença estatística entre si. A longevidade total das hastes não foi influenciada pelos tratamentos. A solução de sacarose pode ser substituída pelos extratos das plantas medicinais estudadas, na conservação pós-colheita de inflorescências de alpínia.

Red ginger (Alpinia purpurata) is a tropical plant found in several Brazilian regions with excellent potential for commercialization as cut flower. However, the senescence of flower stems due to the exhaustion of sucrose is a major factor that affects commercial durability and is suppressed through addition of sucrose in pulsing solutions. The aim of this work was to evaluate the effect of water extracts from stevia (Stevia rebaudiana), star anise (Illicium verum) and sucrose in pulsing solution on the postharvest quality maintenance of red ginger inflorescences. Flower stems of uniform size were subjected to the pulsing solution for 12h at 0.5, 1.0, 2.0 and 3.0 percent concentrations, with distilled water as control. The best commercial quality of inflorescences was obtained when flower stems were kept in pulsing solutions from 1 percent star anise and stevia extracts and in 2 percent sucrose solution, not presenting statistical difference. Total longevity of flower stems was not influenced by treatments. Sucrose solution may be replaced by extracts of the studied medicinal plants in the postharvest conservation of red ginger inflorescences.