ABSTRACT The immediate need for the increase in wheat production to meet the future world demand, associated with the occurrence of drastic climatic events, such as drought, makes it necessary to develop drought-resilient genotypes. The aims of this work were to evaluate the use of drought-tolerance indices for the selection of wheat genotypes, to compare the genetic gains in grain yield using different selection strategies by means of a multi-trait index, and to select superior drought-tolerant wheat genotypes. The total of 31 tropical wheat lines was evaluated in two experiments. Five agronomic traits were accessed. The grain yield data from the stress and nonstress experiments were used to obtain five drought-tolerance indices. The data were subjected to mixed model analysis, and four selection scenarios were designed. There was a significant effect of genotype for all traits. The inclusion of drought-tolerance indices in the selection index provided superior genetic gains in drought condition. Seven lines were selected due the high frequency of favorable alleles for drought-tolerance and other important agronomic traits. Drought-tolerance indices are appropriate for characterizing the response of wheat genotypes to drought-stress. The inclusion of drought-tolerance indices along with agronomic traits in multi-trait selection strategies provides for superior gains in grain yield compared to the non-inclusion of the indices.

ABSTRACT Tephrosia egregia Sandwith is a species that develops in some States of the Northeast region of Brazil. It is propagated by seeds and has considerable potential for restoration. Thus, studies related to seed germination are important for the species. The aims were to characterize the post-seminal development and evaluate the germination response of the seeds under different temperatures and water stress and salt stress. Germination tests were performed at 20, 25, 30 and 20-30 °C and under PEG 6000 and NaCl concentrations (-0.2, -0.4, -0.6 and -0.8 MPa). The germination test should be conducted in a paper roll at 25 ºC for 14 days. Seed germination declines from the water potential of -0.2 MPa on; the species is sensitive to water stress. Under salt stress, there is more accentuated decline in germination as from -0.4 MPa, and this is an indication have a certain tolerance to salinity.

RESUMO Tephrosia egrégia Sandwith é uma espécie que se desenvolve em alguns Estados do Nordeste. Sua propagação é realizada por meio de sementes, sendo uma espécie potencial para restauração. Os objetivos foram caracterizar o desenvolvimento pós-seminal e avaliar a germinação das sementes sob diferentes temperaturas e sob estresse hídrico e salino. Testes de germinação foram conduzidos a 20, 25, 30 e 20-30 °C e sob concentrações de PEG6000 e NaCl (-0.2, -0.4, -0.6 e -0.8 MPa). O teste de germinação deve ser conduzido em rolo de papel sob temperatura constante de 25 ºC durante 14 dias. A germinação das sementes é reduzida a partir do potencial hídrico de -0.2 MPa, sendo a espécie sensível ao estresse hídrico. Sob estresse salino, a redução mais acentuada na germinação, a partir de -0.4 MPa, sendo isso um indicativo de uma certa tolerância à salinidade.

ABSTRACT: Successive cycles of water absorption and loss favor weathering deterioration, one of the main factors that affect the quality of soybean seeds. This study evaluated the physiological, physical, and morpho-anatomical changes in soybean seeds under weathering deterioration at the pre-harvest phase. Six soybean cultivars (BMX Apolo, DM 6563, NS 5959, NA 5909, BMX Potência, and TMG 1175) were produced in a greenhouse and underwent weathering deterioration through a rainfall simulation system, applying 0, 60, 120, and 180 mm of precipitation at pre-harvest phase. Each rainfall level was divided into two applications at an interval of 72 h: 60 mm (30 + 30), 120 mm (60 + 60), and 180 mm (90 + 90). After harvest, the seeds were evaluated for germination, vigor, physical and morpho-anatomical properties. Weathering deterioration induced by simulated rainfall at the pre-harvest phase contributes to the reduction in soybean seed germination and vigor and is conditioned by the soybean genotype. The increase in intensity of simulated rainfall led to a more significant weathering damage in seeds, as evidenced by the X-ray and tetrazolium test. Cultivars DM 6563 and BMX Potência were more susceptible, while NA 5909 was less susceptible to weathering deterioration (especially at the highest level; 120 mm and 180 mm). Anatomical changes caused by weathering deterioration lead to cell compaction and rupture, mainly in the cell layers of the hourglass and parenchyma, forming intracellular spaces. The presence of weathering damage caused a reduction in physiological soybean seed quality.

Resumo Orchidaceae é a maior família de plantas vasculares, e constitui-se num grupo sob intensa ameaça devido à ação antrópica. Cattleya caulescens e C. endsfeldzii são espécies rupícolas endêmicas de Minas Gerais, Brasil, e figuram em listas vermelhas de espécies ameaçadas de âmbito estadual e nacional. Sendo assim, foram conduzidos estudos morfoanatômicos com o objetivo de incrementar os conhecimentos desses táxons, tendo em vista o potencial que esses estudos representam no manejo de espécies. Cattleya caulescens e C. endsfeldzii apresentam fortes similaridades morfoanatômicas, o que apoia estudos anteriores, que incluem ambas numa mesma seção do gênero. Diversas características anatômicas aqui descritas (epiderme unisseriada, folha hipoestomática, grandes campos de pontuações primárias no parênquima clorofiliano e a anatomia da raiz) são comuns a várias outras espécies de Orchidaceae. Os caracteres xeromórficos observados estão relacionados às condições edafoclimáticas, já que ocorrem em substrato rochoso, em constante exposição aos raios solares e restrição hídrica severa durante a maior parte do ano. Este trabalho contribui para se ampliar o conhecimento do gênero Cattleya e auxiliar na delimitação taxonômica destas espécies ameaçadas, ocorrentes em áreas de intensa atividade antrópica.

Abstract Orchidaceae is the largest family of vascular plants and is a group under intense threat due to anthropic activities. Cattleya caulescens and C. endsfeldzii are endemic rupiculous species of Minas Gerais state, Brazil, and listed on Red Lists of endangered species at state and national levels. We conducted morphoanatomical studies with the vegetative organs of the two species, with the objective of increasing knowledge of these taxa, considering the potential that these studies represent in the management of species. Cattleya caulescens and C. endsfeldzii show strong morphoanatomical similarities, which corroborates with previous studies that include both species in the same section of the genus. Many anatomical features described here (presence of single-layered epidermis, stomata only on the abaxial side of the leaf, large primary pit fields in the chlorophyll parenchyma and root anatomy) are common to several other species of Orchidaceae. The xeromorphic features observed in C. caulescens and C. endsfeldzii are related to edaphoclimatic conditions, since they grow on rocky substrate, in constant exposure to solar light and severe water restriction during most of the year. This work contributes to increase the knowledge about Cattleya genus and to support in the taxonomic delimitation of these endangered species occurring in areas of intense antropic activity.

Resumo Coléteres são estruturas secretoras que produzem uma substância pegajosa, constituída por uma mistura de mucilagens, proteínas, terpenos, substâncias pécticas e até alcaloides, que lubrifica e protege o meristema apical. Vários tipos de coléteres têm sido descritos e apresentam valor taxonômico em muitas famílias botânicas. Em Myrtaceae, a descrição de coléteres é recente apresentando três novos tipos morfológicos (cônico, euriforme e petalóide) que diferem dos já descritos para outras eudicotiledôneas. Neste trabalho, são descritos os tipos morfológicos de coléteres em seis espécies de três gêneros pertencentes à tribo Myrteae da subfamília Myrtoideae do Cerrado brasileiro. As amostras foram fixadas para microscopia de luz e eletrônica de varredura. Testes histoquímicos foram realizados em material fresco e em incluído em metacrilato. Foram observados coléteres cônico e euriforme, que não diferiram nem morfoanatomicamente nem quanto à natureza de secreção, daqueles já descritos para espécies de Myrtoideae, o que pode indicar seu uso potencial para fins taxonômicos. Considerando a hipótese de que as linhagens múltiplas de frutos carnosos evoluíram de forma independente na tribo Myrteae, nossos resultados indicam a relevância de estudos adicionais para se reconhecer o padrão de distribuição de coléteres em Myrtaceae.

Abstract Colleters are secretory structures that produce a sticky substance, consisting of a mixture of mucilage, proteins, terpenes, pectic substances and even alkaloids, which lubricates and protects the shoot apical meristem. Several colleter types have been described and have taxonomic value in many botanical families. In Myrtaceae, the colleters description is recent and presents three new morphological types (conic, euryform and petaloid) that differ those already described for other eudicots. In this work, we report the colleters morphological types in six species of three genera belonging to the Myrteae tribe of Myrtoideae from the Brazilian Cerrado. The samples were fixed for light and scanning electron microscopy. Histochemical tests were carried out on the fresh and methacrylate-embedded material. The conic and euryform colleters from Myrtoideae species of the Cerrado did not differ either morphologically nor as to the secretion nature from those described for Myrtoideae species from others biomes, which may indicate their potential use for taxonomic purposes. Considering the hypothesis that the multiple fleshy-fruit lineages have evolved independently in Myrteae tribe, our results indicate the relevance of additional studies in order to recognize the pattern of distribution of colleters in Myrtaceae.