Rinaldo Pires dos Santos

Reprodução do pessegueiro: efeito genético, ambiental e de manejo das plantas

ABSTRACT – In Brazil there is a great lack of studies and literature about the peach reproduction. The present review discusses a lot of research results regarding the main factors involved in the reproduction of this species, and it has the intention to help future researches that aims to understand or to resolve the problems associated with the reproduction of the peach tree. By this review it was possible to verify that the process of fruit set is complex for some cultivars and highly dependent on each phenological stage. The ability of the professionals and producers to integrate the factors rootstocks, variety, environment and adequate cultural practices is very important for a successful peach tree production. Index terms: reproduction, peach, genetic, environment, cultural practices. INTRODUCAO O coe fi ciente de herdabilidade para produtivi-dade em pessegueiros e da ordem de 0,08 (Hansche, 1986), ou seja, de 8%. Este fator demonstra que o sucesso na frutifi cacao e producao dessa especie e dependente, sobretudo, das condicoes de manejo e de ambiente circundante do pomar. Assim sendo, a fruti-fi cacao e a producao da maioria das plantas frutiferas temperadas, incluindo o pessegueiro, estao associa-das, num primeiro momento, ao desenvolvimento adequado das gemas fl orais. Com isso, os manejos nutricional e fi tossanitario das plantas apos a colheita, bem como condicoes ambientais adequadas para su-peracao da dormencia das plantas sao fundamentais. Num segundo momento, condicoes meteorologicas favoraveis para a abertura das gemas, polinizacao e fecundacao das fl ores sao cruciais.Problemas de “fi xacao” de frutos nao sao muito comuns em pessegueiros. De maneira geral, a frutifi cacao e abundante, havendo necessidade de realizacao de raleio intenso, para promover o de-senvolvimento satisfatorio de um numero adequado de frutos por planta, que e variavel principalmente em funcao da idade, porte e do estado nutricional das plantas. Entretanto, nos ultimos anos, algumas cultivares de pessegueiros, nectarineiras e ameixeiras vem apresentando baixa frutifi cacao e/ou irregula-ridade de producao, em distintos locais da regiao Sul do Brasil. Dentre elas, podem ser citadas as cultivares de pessegueiro Granada e Riograndense (Nava, 2007).Na cultivar de pessegueiro Granada, vem-se observando, na maioria dos anos, baixas taxas de frutifi cacao efetiva. Este fenomeno ja foi constatado

Aperture types of pollen grains of Passiflora L. species (Passifloraceae)

Palynological studies reveal a wide variation in shape, number and types of apertures in Passiflora pollen grains. This study aimed to characterize pollen grain apertures of eleven species of Passiflora from Rio Grande do Sul state and two species from Santa Catarina state (Brazil), belonging to three of the four subgenera now recognized: Astrophea, Decaloba and Passiflora. Several techniques of light and scanning electron microscopy were employed. Passiflora haematostigma (Astrophea) has 6-colporate pollen grains with three lalongate endoapertures. Passiflora alata, P. amethystina, P. caerulea and P. edulis (Passiflora) have 6-colpate pollen grains, with fusion of ectoapertures pairs in the apocolpium. Passiflora actinia, P. elegans and P. tenuifila (Passiflora) have pollen grains with 6 to 12 colpi, also fused in pairs. Passiflora misera, P. morifolia, P. suberosa and P. truncata (Decaloba) have 6-colporate operculate pollen grains, with differences in endoaperture size and operculum width. Passiflora capsularis (Decaloba) has 12-colporate pollen. The main palynological terms and synonyms in the literature are discussed.

A comparative survey of floral characters in Capanemia Barb. Rodr. (Orchidaceae: Oncidiinae).

BACKGROUND AND AIMS Capanemia Barb. Rodr. comprises seven species that mostly inhabit the Brazilian Atlantic Rain Forest domain. The genus currently consists of two sections: Capanemia Cogn. and Planifolia Pabst, distinguished on the basis of leaf shape. We compare the floral morphology and anatomy of all species to determine whether separation into sections is supported by floral characters. METHODS Both fresh flowers and herbarium specimens were investigated, and column and pollinarium features, together with the presence or absence of floral rewards, recorded. Anatomical features were examined using both light microscopy and scanning electron microscopy. KEY RESULTS AND CONCLUSIONS With the sole exception of Capanemia therezae, all species shared a distinctive set of floral characters. Flowers were mostly white or yellowish-white and fragrant, and column wings were positioned parallel to the labellum, concealing the stigmatic cavity. Pollinaria had proportionally long tegular stipes and clavate to reniform pollinia, whereas the labellum possessed a conspicuous indument of trichomes, but was devoid of nectar or any other secretion that might function as a food-reward. Capanemia therezae, however, was exceptional in having greenish, unscented flowers with short, rounded and divergent column wings and an exposed stigmatic cavity. Its pollinaria had proportionally short tegular stipes and round pollinia, whereas the labellum lacked trichomes. Droplets of nectar were evident on the adaxial surface of the labellum, adjacent to the callus. Floral features did not support the currently accepted sectional division of Capanemia. If ongoing phylogenetic studies demonstrate that both sections are indeed monophyletic, then these taxa should be distinguished solely on the basis of foliar features.

Storage substances in the androgametogenesis and mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae)

Storage substances such as starch grains, proteins and lipids were studied during the male gametogenesis and in the mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae). There are two cycles of amylogenesis and amylolyse. The first cycle lasts until the vacuolated stage when the starch is hydrolyzed and amorphous proteins are stored inside the single vacuole. The next cycle begins after mitosis with the formation of the vegetative and generative cells. At this point, the young vegetative cell stores many starch grains that are bigger than in the first cycle. During the maturation of the male gametophyte, the starch is hydrolyzed and it is absent in the mature pollen grain. Small lipid droplets surround the young generative cell after the mitosis of the androspore and are dispersed in the vegetative cytoplasm during its maturity. The relationship between the pollen storage substances and the ontogeny of the layers in the sporoderm, formation of the generative cell, and the male germ unit were discussed.

A simple method for fixing, dehydrating and embedding pollen tubes cultivated in vitro for optical and transmission electron microscopy.

A simple method to cultivate pollen tubes in a gelatin medium is presented. After the growth of the pollen tubes in the culture medium, they are fixed, dehydrated, and embedded in resin for ultramicrotomy. The method is easy and does not require the purchase of special materials beyond those needed for the usual techniques for studying biological specimens under transmission electron microscopy.