Are rhododendron hybrids distinguishable on the basis of morphology and microsatellite polymorphism?

Sequence Tagged Microsatellite Sites (STMSs) and morphological trait markers were used to evaluate 33 rhododendron germplasm for genetic diversity assessment and discrimination power. The average genetic diversity estimates were 0.724 (morphological traits) and 0.174 (STMSs) marker datasets. The Shannon index was higher for morphological traits (1.797) than STMS (0.302). The correlation coefficients obtained by the Mantel matrix correspondence test, which was used to compare the cophenetic matrices for the two markers, showed that estimated values of relationships given for morphological and STMS were not significantly related (p > 0.05). The dataset from STMS, supported by the total probability of identity (1.13 × 10⁻⁹) and total paternity exclusion probability (0.9999), allowed all accessions to be uniquely identified. In summary, STMS marker proved to be an efficient tool in assessing the genetic variability among old broad leaf rhododendron genotypes. The pattern of variation appeared to be consistent, and it can be used for germplasm conservation and management for restoration of historical genetic resources.     

Effects of logging, liana tangles and pasture on seed fate of dry forest tree species in Central Brazil

We assessed seed fate of six tree species in a seasonally deciduous forest of Central Brazil. Seed germination, predation, removal and death caused by pathogens or dessication were followed in an undisturbed forest site, a logged forest site, and an active pasture. In both forest types we sowed seeds under patches of liana tangles (Low Forest habitat) and under patches of mature forest (High Forest habitat). Seeds were monitored weekly for up to 8 months. Overall, small-seeded species (Astronium fraxinifolium and Tabebuia impetiginosa) had high germination, although germination was lower in the pasture due to insect predation. The hard-coated seeds of Erythrina sp. had higher germination rates in the pasture. The large-seeded Cavanillesia arborea and Swartzia multijuga had high seed removal (ca. 90%) in the pasture and under High Forest, but only 23–34% under Low Forest in the logged site. Lower removal of large seeds in Low Forest suggests that this habitat conceals the seeds and constrains the movement of large mammals. Both species were favored in Low Forest, suggesting that caution should be used when managing lianas. When protected from predation, seeds with a soft coat and high water content, such as the seeds of Eugenia dysenterica and S. multijuga, died from desiccation in the pasture. Restoration efforts must take into consideration high mortality caused by desiccation or insect predation in abandoned pastures of dry forests.     

Pollen morphology as fertility predictor in hybrid tea roses

Fertility of hybrid tea roses is often reduced due to their interspecific origin but also to intensive inbreeding. New genotypes used as pollen donors represent an economic risk for a breeding programme, as their influence on seed production is unknown. In this study 11 cut rose genotypes were selected from a company database as high fertile or low fertile male parents, according to the number of seeds per hybridisation. Pollen morphology and in vitro germination of the selected genotypes were characterised. Pollen was either small (mean diameter <30 μm), shrunken, and irregular (abnormal), or large (mean diameter >30 μm), elliptical and crossed by furrows (normal). High correlations were found between the number of seeds produced per hybridisation and the pollen diameter (r = 0.94) or the percentage of normal pollen (r = 0.96). In order to evaluate the predictive power of the models, we conducted regression analyses and performed a validation experiment on genotypes not present in the database and without background information on fertility. Pollen diameter and percentage of normal pollen were characterised and fitted in the regression models for seed set predictions. Validation with an independent dataset gave a good prediction for 83.3% of the data. This indicates that using either the mean pollen diameter or the percentage of normal pollen resulted in effective fertility prediction. This tool could enhance the genetic variability in crossings between hybrid tea roses, thus creating possibilities for less economically risky exploitation of new tetraploid genotypes as male parents.     

Comparative study of the discriminating capacity and effectiveness of AFLP, STMS and EST markers in assessing genetic relationships among evergreen azaleas

The application of amplified fragment length polymorphism (AFLP), sequence tagged microsatellite site (STMS) and expressed sequence tag (EST) markers to study the genetic relationships in an evergreen azalea gene pool was investigated. STMS and EST markers revealed a higher genetic distance detection capacity than AFLPs, which, nevertheless, were the most efficient marker system due to their highest polymorphism detection capacity. Similarity matrices showed weak, yet significant, correlations when Mantel's test was applied. To assess the usefulness of the overall information provided by these marker data for establishing phylogenetic relationships and horticultural classification, cluster analysis was performed. The joint AFLP, STMS and EST data were demonstrated to be remarkably effective for group discrimination and phylogenetic studies. The use of these polymerase chain reaction marker systems is discussed in terms of the choice of appropriate marker techniques for different aspects of evergreen azalea germplasm evaluation.     

Consequences of dry-season seed dispersal on seedling establishment of dry forest trees: Should we store seeds until the rains?

We examined the following hypotheses: (i) seeds of dry forest trees have high pre- and post-germination mortality by desiccation due to the time between seed dispersal and germination and to irregular rains at the onset of the rainy season; (ii) seedlings from seeds dispersed in the dry season which survive the dry spells are larger at the end of the first rainy season than those dispersed in the rainy season because the former have more time to grow. We evaluated the possible trade-off between few large seedlings (resulting from natural dispersal) × many small seedlings (resulting from delayed dispersal) on seedling survival during the dry season. We sowed eight tree species in a greenhouse in September, simulating the natural dispersal timing (before the rains), and in November, when rains are more constant. Because shading can counteract the effects of desiccation, we applied three levels of shade (10%, 40% and 72% of PPFD). From September 2005 to December 2006, we provided the daily precipitation of a median year from a major patch of dry forest in Central Brazil. At the end of the rainy season, a subset of seedlings was collected for growth measurements (dry mass) and the remainder was left to follow the dry season survivorship. The lower germination expected for seeds dispersed in the dry season and in full sun was not confirmed for species that had some dormancy. The delayed dispersal was advantageous for the initial establishment of fast germinating species, but it was irrelevant or even disadvantageous for others. Also, the greenhouse weather was certainly milder than the natural environment, reducing the potential for mortality by desiccation. The growth of the four species of higher dormancy were not affected by timing of seed dispersal, while three out of four fast germinating species had higher root biomass when dispersed in the dry season. The growth during the rainy season did not affect seedling survival during the dry season. Keeping seeds to sow when rain is constant might be a good strategy to increase the establishment of fast-germinating tree species.     

Use of 1-methylcylopropene in cyclodextrin-based nanosponges to control grey mould caused by Botrytis cinerea on Dianthus caryophyllus cut flowers

Botrytis cinerea is one of the pathogens resulting in the heaviest commercial losses in ornamental cut flowers, and the severity of grey mould disease partly depends on the presence of ethylene in the storage environment. The efficacy of a β-cyclodextrin-based nanosponge 1:8 (CD-NS) - 1-methylcyclopropene (1-MCP) complex was evaluated as a novel control agent in protecting carnation (Dianthus caryophyllus L. ‘Idra di Muraglia’) cut flowers against B. cinerea infection. Two concentrations of this non-volatile 1-MCP formulation (CD-NS complex, 0.25 and 0.5 μL L⁻¹, a.i.) were compared with commercial gaseous 1-MCP (0.25 μL L⁻¹, a.i.), and an inoculated control. A non-inoculated control was also used to assess the natural infection level. Eleven days after inoculation, the development of grey mould on carnation was significantly reduced (59.9% of flower surface) in cut stems treated with the CD-NS complex at low dosage, compared to the high dosage of the CD-NS complex (91.5%), the commercial gaseous 1-MCP formulation (76.2%) and the inoculated control (100.0%). Endogenous ethylene production was associated with symptom development. Results showed a reduced ethylene production in 1-MCP treated flowers (0.25 μL L⁻¹, a.i., both suspended and gaseous formulation). The CD-NS complex could therefore be an effective alternative to conventional chemicals to protect ornamental cut flowers.     

Colletotrichum species causing grape ripe rot disease in Vitis labrusca and V. vinifera varieties in the highlands of southern Brazil

Ripe rot is one of the most important bunch diseases of grapes in the highlands of southern Brazil and a matter of concern for winegrowers. Sixty-one strains isolated from berries of Vitis labrusca and V. vinifera varieties with symptoms were classified by phylogenetic analysis of the sequences of β-tubulin, glyceraldehyde-3-phosphate dehydrogenase, D1/D2 domain of 28S rDNA, and rDNA internal transcribed spacer. They were also characterized by morphology, and their pathogenicity was evaluated. The combined molecular data allowed identification of six Colletotrichum species: C. fructicola, C. kahawae and C. viniferum (gloeosporioides complex), C. limitticola, C. nymphaeae (acutatum complex), and C. karstii (boninense complex). This is the first report of C. karstii and C. limitticola associated with the ripe rot of grapes. Morphological characteristics varied within and among species, confirming their separation at the complex level. Pathogenicity tests on V. vinifera berries showed that the most prevalent species, C. viniferum (37.8%) and C. fructicola (36.1%), were more virulent than the less prevalent species C. limitticola and C. karstii. Our findings indicate that there is a high diversity of Colletotrichum species associated with ripe rot disease of grapes in Brazil. There were no clear differences in the distribution of Colletotrichum species between V. labrusca and V. vinifera varieties. The determination of fungal species responsible for grape ripe rot in Brazilian vineyards may contribute to further epidemiological studies and the development of more efficient prophylactic methods for ripe rot management.     

Tree seedling survival and growth in logged and undisturbed seasonal deciduous forest fragments in central Brazil

We evaluated the survival and growth of Amburana cearensis, Cedrela fissilis, and Sterculia striata seedlings in three seasonally tropical dry forest fragments that were subjected to different logging levels (intact, intermediately and heavily logged). In each fragment, we planted 40 seedlings of each species and monitored these over a period of 1 year. The highest seedling survival rate (64%) occurred in the heavily logged fragment, which, however, also had the highest mortality risk for all species during the dry season. Only S. striata seedlings had different survival rates among the fragments. Height and diameter growth were higher at sites with higher canopy openness in the wet season. The survival and growth rates of seedlings planted in logged fragments indicate that this technique can be applied to restore and enrich logged forests of the Paran? River Basin.     

The effects of 1-MCP in cyclodextrin-based nanosponges to improve the vase life of Dianthus caryophyllus cut flowers

The present research investigated the effects of a non-volatile formulation of 1-methylcyclopropene (1-MCP) embedded in different cyclodextrin (CD)-based nanosponges (NSs) to extend the postharvest longevity of an ethylene-sensitive carnation cultivar. Cut flowers of Dianthus caryophyllus L. ‘Idra di Muraglia’ were treated with α- and β-CD-based nanosponge-1-MCP complexes (α- and β-NS complexes) in tap water to achieve two different concentrations of active ingredient (0.25 and 0.5 μL L^?1). Treated flowers were compared to cut stems exposed to equivalent concentrations of volatile 1-MCP as well as a tap water control with or without pure α- and β-NS. Identical nanoporous compounds were applied by perfusion to yield a total of 15 treatments. Twenty-four hours after the treatments were applied, the cut flowers were exposed to exogenous ethylene (1 ± 0.2 μL L^?1) for 24 h. The postharvest carnation flower and leaf quality in addition to ethylene production levels were determined daily (beginning 24 h after treatment). None of the α-NS complex applications statistically improved the vase life of cut flowers; however, β-NS complexes were effective in preventing senescence, reducing ethylene production (measured at nearly nil after 11 d), and maintaining original petal color longer. These results were particularly strong at the lowest concentration (0.25 μL L^?1) of β-NS complex. Overall, this method promoted cut flower longevity (loss of ornamental value after 14.7 d; complete damage at day 18.5) better than the commercial 1-MCP gaseous application method.     

Impacts of the implementation of silvopastoral systems on biodiversity of native plants in a traditional community in the Brazilian Savanna

Large-scale commercial cattle ranching is the main driver of deforestation in the world, with several negative environmental and social impacts. To meet the growing demand for animal products, silvopastoral systems (SPS) can be an alternative as they have greater biodiversity and offer more environmental services than conventional cattle ranching systems. This paper aims to describe the implementation of SPS by traditional farmers in a rural settlement in southeastern Brazil, and the impacts on biodiversity of native plants. SPS were implemented by farmers in three selected areas that were cleared with a tractor. The impacts on the community and populations of native plants were estimated through vegetation sampling before and after the implementation of the SPS. Direct observations and semi-structured interviews were conducted to describe the implementation of the system and to understand the criteria employed to spare species, to manage native plants and the advantages of these systems according to farmers’ perceptions. Before the implementation, 1038 trees from 50 species and 29 botanical families were surveyed in the three areas. The tractor cleared on average 72 % of the trees, decreasing the number of trees ha^?1 from 692 to 180 and reducing tree richness in 43 %. On average, 89 % of the removed trees had diameter ranging from 5 to 10 cm, indicating farmers’ preference in sparing the thickest trees. Farmers also spare useful species that have socio-economic importance, such as timber, fruit trees, fodder and medicine. According to the farmers, the advantages of the SPS are the high concentration of useful species, the environmental services provided and the increase in livestock production. The system described has great potential to ensure food security, generating socio-economic benefits for farmers and contributing to biodiversity conservation.