The post-fire effects on the outcrossing rate of a Brazilian savannah shrub, Helicteres sacarolha A.St.-Hil

The effect of post-fire, plant density and number of flowers per plant on outcrossing rates was examined in a Brazilian savannah shrub, Helicteres sacarolha. Data on number of flowering plants and flowers per plant were collected during the flowering season in January and February of 1994. In October of 1994, a fire swept through the studied area after 30 years of fire absence. The burnt plants of H. sacarolha resprouted, producing flowers and fruits in 1995. Seeds from several plants in both years were collected. Allozyme markers were used to estimate the multilocus outcrossing rates for 1994 and 1995 progenies. After the fire, outcrossing rates increased. In 1995, plants flowered vigorously, increasing flower density and probably pollinator activity. Helicteres sacarolha seems to be fire resistant, like other plant species of the Brazilian savannah, but several plants tagged in 1994 were not found after the fire, and may have died. Thus, although genetic diversity and outcrossing rates increased following the fire in 1994, repeated events of fire may decrease drastically the population size of H. sacarolha, leading to a diminished genetic diversity and outcrossing rates.

Reproductive phenology, pollination and seed dispersal syndromes on sandstone outcrop vegetation in the "Chapada Diamantina", northeastern Brazil: population and community analyses

Vegetation on rock outcrops in the "Chapada Diamantina" (soil islands) is often aggregated and surrounded by nude rock surfaces, thus creating natural units with well defined limits. The flowering and fruiting cycles of plants on 58 soil islands at altitudes between 1,100 and 1,140 meters above sea leavel were analyzed at Mãe Inácia Peak (12°27' S and 41°28' W) in the "Chapada Diamantina", Bahia, Brazil. The presence/absence of flowering and fruiting species on each soil island, and their respective cover areas were analyzed at both the population and community levels, and the phenophases of flowering and fruiting were observed during 24 successive months. The analyses of pollination and seed dispersal syndromes indicated that animals are more important in pollination than in seed dispersal (which is predominantly by anemochory and autochory). The flowering and fruiting of plants with animal pollination syndromes were correlated with rainfall and temperature. The flowering season varied during the year according to the pollination syndrome involved: entomophily was predominant from summer through autumn, ornithophily was predominant during winter, and anemophily in the spring. The staggered timing of flowering and fruiting among different species provides a nearly continuous supply of resources for the local fauna.

Reproductive phenology of Melocactus (Cactaceae) species from Chapada Diamantina, Bahia, Brazil

This paper discusses the phenological strategies of Melocactus glaucescens Buining & Brederoo, M. paucispinus G. Heimen & R. Paul, M. ernestii Vaupel and M. ×albicephalus Buining & Brederoo, species from Chapada Diamantina, northeastern Brazil. Melocactus glaucescens, M. ernestii and M. ×albicephalus occur sympatrically in an area of "caatinga"/"cerrado" vegetation, and M. paucispinus in an area of "cerrado"/"campo rupestre". The superposition of flowering in these sympatric taxa was compared and analyzed. The phenology of M. paucispinus was correlated with both abiotic and biotic factors. Flowering of M. glaucescens and M. ×albicephalus were observed to be continuous (though with moderate peaks of activity), while fruiting was sub-annual. Melocactus ernestii exhibited an annual pattern of both flowering and fruiting; while in M. paucispinus the same patterns were sub-annual. These sympatric taxa showed 40% overlap of flowering periods, reaching to more than 50% in paired combinations of taxa, considering both the number of specimens flowering, as well as the quantity of resources being offered. Available information indicates that these taxa share pollinators, but phenological data rejects the hypothesis of shared pollinators and supports the hypothesis of hybridization in the study area. Rainfall was negatively correlated with flowering in M. paucispinus, but positively correlated with fruiting. Flowering of M. paucispinus in dry periods of the year avoids that erect flowers positioned in terminal cephalium, exposed in open areas of the vegetation, be damaged for the rains, while fruiting in rainy periods can be favorable to the dispersion and germination of this species.

Floral resources used by insects in a grassland community in Southern Brazil

The goal of the present study was to identify plant species used as food source, the floral resources utilized, and the insects that visit flowers in a grassland community in southern Brazil. The study was carried out in an area of one hectare, located in a grassland formation in the Parque Estadual de Itapuã, State of Rio Grande do Sul, Brazil. The flowering pattern was seasonal, and richness and abundance of insects was higher during the period of high resource availability. Flowers of 106 species of angiosperms (73 genera and 34 families) were used as source of floral resources for 219 species (2,767 specimens) of insects. A total of 91.5% of plant species were visited by bees, 53.8% by flies, 34.9% by wasps, 22.6% by butterflies, and 12.3% by beetles. Nectar was the main resource consumed by the visitors (41.1%). Asteraceae was the richest (38 spp.) and most visited family, with 63.1% of the species and 49.5% of all specimens of recorded insects. Bees were the most representative insects (33.2% spp., 65% indiv.), followed by flies (26.9% spp., 16.5% indiv.), wasps, butterflies and beetles. 40 plant species were considered important resources for the floral visitors' community, due to high number of, both, species and individuals recorded in their flowers. The family Asteraceae as a species set was the main floral resource used by insect visitors through the year and has great importance for the maintenance of populations of many species of bees, flies, wasps and butterflies in the studied area.

Pollination biology in Jacaranda copaia (Aubl.) D. Don. (Bignoniaceae) at the "Floresta Nacional do Tapajós", Central Amazon, Brazil

Jacaranda copaia (Aubl.) D. Don is a pioneer tree widespread in the Brazilian Amazon, usually found colonizing forest gaps and altered areas, and the forest fragment edges. This study investigated aspects of the floral biology, breeding system and pollinators of J. copaia trees. Flowering lasts from August to November, during the low rainfall period extending up to four weeks per tree and 3-4 months for the population as a whole, characterizing a cornucopia flowering pattern. The fruit set ends in the beginning of the rainy season, with wind dispersed winged seeds. Fruit set from open pollination was 1.06% (n = 6,932). Hand pollination using self-pollen (n = 2,099) did not set fruits. Cross-pollination resulted in 6.54% fruit set (n = 2,524), representing six times more than the natural pollination rate (1.06%, n = 6,932). Flowers excluded from insect visitation (automatic self-pollination) did not set fruits (n = 5,372). Pollen tube growth down to ovary was detected under fluorescence microcoscopy in cross-pollinated and selfed pistils. The species is an obligate allogamous plant, with late-acting self-incompatibility system. Approximately 40 species of native bees visited the flowers, but the main pollinators were medium-sized solitary bees as Euglossa and Centris species due to the compatibility between their body sizes with the corolla tube, direct contact with the reproductive structures and high frequency of visits.

Synchrony is more than overlap: measuring phenological synchronization considering time length and intensity

The degree of flowering and fruiting synchronization is believed to have ecological and evolutionary relevance at several scales. Here we discuss some measures that have been used to estimate synchrony and propose an index that incorporates both the entire length of an individual phenophase and variation in the number of flowers or fruits over that time period. This new index describes more accurately the phenological synchrony among individuals and populations.

Are there evidences of a complex mimicry system among Asclepias curassavica (Apocynaceae), Epidendrum fulgens (Orchidaceae), and Lantana camara (Verbenaceae) in Southern Brazil?

The goal of this paper was to test the presence of mimicry in Asclepias curassavica L., Epidendrum fulgens Brong., and Lantana camara L. The study was carried out at the Parque Estadual de Itapeva, RS, southern Brazil, from 2004 to 2006. Flowering period of each of the three species was followed up; focal observations of butterflies visiting flowers, from fixed point and during random walks were carried out. We also estimated the frequency of pollinaria removal in the orchid, as well as its mode of reproduction. All these variables were important for testing the mimicry hypothesis. Despite some temporal coincidences in the flowering period of two plants in the system, there was no statistical association among the three plants as to flowering period. Twenty-nine species of butterflies, as potential pollinators, were recorded, particularly Agraulis vanillae maculosa, Dryas iulia alcionea, Urbanus simplicius, Tegosa claudina, and Heliconius erato phyllis, which were the more frequent visitors of the three plants. There was association between the number of visits to L. camara and E. fulgens, based on Pearson correlation (r = 0.4603; n = 19; P = 0.0473). Pollinaria removal of E. fulgens was low, as measured by the percentage of removal (range: 0 - 10%). The analysis of the mode of reproduction of this orchid showed its pollinator-dependence, since no fruits were formed by spontaneous self-pollination. In contrast, the percentage of fruit set that resulted from geitonogamy and xenogamy was, in average, 86%. The results here shown are not conclusive as to the occurrence of a mimicry system among the three plants.

Reproductive biology of Protium spruceanum (Burseraceae), a dominant dioecious tree in vegetation corridors in Southeastern Brazil

We investigated the reproductive biology of Protium spruceanum (Benth.) Engler in vegetation corridors of secondary Atlantic forest in Lavras, southern Minas Gerais State, Brazil. The reproductive phenology was investigated fortnightly over a one year period. Floral biology studies involved pollen viability analysis, nectar production, stigmatic receptivity, pollen tube growth, visiting insect species and visit rates. The small, pale yellowish flowers (0.3-0.4 cm diameter) are functionally unisexual and organized in dense inflorescences (ca. 45 flowers). P. spruceanum presented annual flowering between September and November. Staminate flowers supplied a high percentage of viable pollen (90.6%) and relatively abundant nectar (x = 4.5 μL). Pistillate flowers produced only nectar to flower visitors (x = 4.0 μL). The effective pollinators were Apis mellifera and Trigona sp. (Hymenoptera, Apidae). Pollen tubes of cross-pollinated flowers were observed entering the ovaries 48 h after pollination. The fruiting season is from October to March, with a peak in November, coinciding with the rainfall peak. Ecological implications of these findings, and alternative arguments to explain the high genetic diversity at regional landscape are discussed.

Mixed reproduction systems in Opuntia monacantha (Cactaceae) in Southern Brazil

The Cactaceae have morphological and physiological adaptations associated with their life histories that are reflected in different modes of reproduction and multiplication. The reproductive phenology, preferential reproductive mode, and the sexual and asexual multiplication of Opuntia monacantha were investigated between 2003 and 2006 in two restinga (sandy coastal) environment in Southern Brazil to determine the adaptive values of its reproduction modes. Flowering was annual and occurred continuous for approximately 100 days between the months of September and January, with a few flowers opening per day per individual (but many in the whole population). Facultative xenogamy was identified as the preferential sexual system, with the highest levels of fruit and seed formation following natural pollination. The seeds are recalcitrant and have high germinative capacities under laboratory conditions. Seedling recruitment and establishment in the field was extremely reduced. The skins of the fruits and the cladodes have high capacities for regeneration and clonal multiplication because of their areolas.

The genera Eriochrysis P. Beauv., Imperata Cirillo and Saccharum L. (Poaceae - Andropogoneae - Saccharinae) in the state of Rio Grande do Sul, Brazil

The subtribe Saccharinae belongs to the tribe Andropogoneae and comprises ca. 140 species in 13 genera, including Eriochrysis, Imperata and Saccharum. This work presents a survey of the species of these three genera in the state of Rio Grande do Sul. Intensive field collections were made in different physiographic regions of the state, as well as studies in several herbaria. The occurrence of three native species of each genus was confirmed in Rio Grande do Sul, in addition to sugar cane (Saccharum officinarum) that is cultivated in the region. Based on the material examined, Eriochrysis villosa is reported for the first time in the state of Paraná, Brazil. Identification keys for the species, descriptions, data on their geographical distributions, habitats and flowering and fruiting periods, as well as illustrations of important taxonomic characters are provided.

Alternative procedures for parent choice in a breeding program for the common bean (Phaseolus vulgaris L.)

Six common bean cultivars were crossed in diallel and the segregant populations were assessed in the F2 and F3 generations to compare methodologies for parental selection in a breeding program based on hybridization. The cultivars involved in the diallel were A 114, A 77, ESAL 686, Milionário, Carioca, and Flor de Mayo. The segregant F2 and F3 generations were assessed on the experimental campus of the Universidade Federal de Larvas, in July 1994. It was found that the cultivars differed in their general combining ability (GCA). Flor de Mayo, which belongs to the Durango race, had the largest positive GCA estimate for grain field, and the cultivars from the Mesoamerican race, Milionário and A 114, the smallest GCA estimates. For flowering, the cultivar that most contributed to reduced plant cycle was ESAL 686. There was agreement among the results obtained from the diallel and the estimates of the parameter m + a of the populations. However, it was evident that the estimate of genetic variance of the populations should be considered as a condition to identify the hybrid population that will produce a line with high performance.

Induction of mutations for earliness in the soybean cultivar Paraná

Mutation induction breeding through gamma ray seed treatment (22 krad) was used to obtain earliness in the soybean cultivar Paraná. Plants flowering earlier than Paraná were selected at the M3 generation. Eight mutant lines were isolated by further selections through several generations and tested in four yield trials carried out in 85/86 (Piracicaba) and 86/87 (Piracicaba, Sertãozinho and Assis) in São Paulo State. The following data were taken in these trials: number of days to flowering, yield, total plant height and height to pod insertion, flower color, pod pubescence and seed and plant growth type. Two of the mutants are of agronomic interest because they were, on average, seven to 10 days earlier in maturity than the control in all trials. Except for shorter plant height, the other agronomic characteristics remained unaltered.

Estimates of genetic and phenotypic parameters in a segregant population of rice irrigated by continuous flooding

Estimates of genetic and phenotypic parameters were obtained by using data from families of a recurrent selection program in rice. An experiment using population CNA-IRAT 4ME/1/1 was conducted at two locations (Lambari and Cambuquira) in the State of Minas Gerais, Brazil. At Lambari, families S0:2 and S0:3 were assessed during crop seasons 1992/1993 and 1993/1994, respectively. In the Cambuquira trial, only S0:3 families were tested in 1993/1994. The experimental design was a 10 x 10 lattice with three replications. The following traits were assessed: grain yield (GY), mean number of days to flowering (FL), plant height (PH), and the incidence of neck blast (NB) caused by Pyricularia grisea and grain staining (GS) caused by Drechslera oryzae. This population proved to be promising for recurrent selection, as it had high average yield and genetic variability. Heritability estimates obtained using variance components were generally greater than estimates of realized heritability, and heritability obtained by parent-offspring regression

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of São Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable.

Chemical and physical characterization of mume fruit collected from different locations and at different maturity stages in São Paulo State

Prunus mume is widely studied due to its health benefits regarding increase of blood fluidity and consequent improvement of the cardiovascular system and the prevention or even the fight against different types of cancer. However, in Brazil this culture is found only among oriental descendants. The present study aimed to characterize mume fruit collected from three different locations in the State of São Paulo regarding general aspects such as pH, total titratable acidity (TTA), total soluble solids (TTS), pectin content and yield of pulp and chemical characteristics: total phenolic compounds (TPC) and antioxidant capacity. Mume fruit were collected unripe and analyzed until maturation about 88 days after flowering. Fruit collected in Botucatu came from a commercial mume fruit producer and had average weight of 16.9 g, while in fruit from other locations weight varied from 5.7-6.9 g. TSS ranged from 9.5 to 10.0 Brix, total solids was 10.2-12.2% and pH showed values between 2.5 and 2.7 for all locations. TTA expressed in citric acid decreased from 4.0-5.7 g (100g- 1) at unripe stage to 2.0-3.8 g (100g- 1) in mature-stage fruit. Pectin content decreased from 11.2 to 10.8% during fruit maturation, TPC content was 147-226 mg catechin (g- 1) on a dry matter basis and the antioxidant capacity was 96-169 µMol Trolox (g- 1) on a dry matter basis or 21-34 µMol Trolox (g- 1) on a wet matter basis.