Cybistax Research Articles

Predicting temperature ranges for the initial development of two native Brazilian tree species using multiple sowing dates

Accurate data on development responses to air temperature are essential to feed development and productivity models through which it is possible to analyze the global warming impacts. The cardinal temperatures – base (Tb), optimum (Topt), and maximum (TB) - delimit the temperature range in which development occurs, while the phyllochron (ºC day per leaf) defines the thermal requirements necessary for leaf appearance and development rate of tree species. Field experiments employing multiple sowing dates provide a wide range of temperature regimes closer to natural field conditions and, at the same time, allow obtaining accurate and reliable estimates of cardinal temperatures and phyllochron values. This study estimated the cardinal temperatures – Tb, Topt, and TB – and the phyllochron of tree species Cybistax antisyphilitica (Mart.) Mart. and Platycyamus regnellii Benth., both native to Brazil, using multiple sowing dates. For this, leaf appearance data from field experiments conducted outdoors during the 2017 and 2018 growing seasons with twelve sowing dates were used. C. antisyphilitica develops properly among 13 °C (Tb), 20 °C (Topt), and 48.4 °C (TB) temperature ranges, and P. regnellii among 13.7 °C (Tb), 21.5 °C (Topt) and 43.4 °C (TB). The phyllochron for leaf appearance was different between the two species. On average, C. antisyphilitica needs to accumulate 88.2 °C day to emit a leaf on the main stem, while P. regnellii needs to accumulate 109.7 °C day per leaf, and both values correspond to a development rate of 0.0134 and 0.0091 leaf per ºC day, respectively. Information about cardinal temperatures provides valuable insights into the development patterns and thermal requirements, which can be used in development models to project the development under future climates.

Phenological description and thermal time requirements for the seedling phase of three Brazilian native forest species

AbstractUnderstanding the phenological stages and thermal requirements of the seedling phase of forest species is crucial for sustainable nursery management. This study proposed an adaptation of a phenological scale based on the basic Biologische Bundesanstalt, Bundessortenamt, and Chemical industry, associated with the thermal requirement to describe the phenological stages during the seedling phase of three forest species: Cybistax antisyphilitica, Libidibia ferrea, and Platycyamus regnellii. The phenological scale of C. antisyphilitica and L. ferrea was defined and described through 22 seedling development stages ranging from dry seed to 20th visible leaf emitted on the main stem (from 00 to 120) and P. regnellii for 12 leaf development stages, from dry seed to 10th visible leaf emitted on the main stem (from 00 to 110). In addition, the duration (days) and thermal time (°C day) were determined for each seedling development stage. C. antisyphilitica needs to accumulate more energy (and days) to finish the seedling phase (1551.9°C day or 261 days) compared to L. ferrea (1127°C day or 175 days) and P. regnellii (1109.7°C day or 193 days). However, the three forest species exhibit similar energy demands throughout most stages of seedling development, except code 09–12 for C. antisyphilitica. This study provides important information for optimizing silvicultural techniques, evaluating the response of temperature on phenological stages, and assessing the impacts of global warming on forest seedling development.

Modeling the initial development dynamics for two native Brazilian forest tree species

Abstract Development models are used to quantify the dynamics and rate of initial development, the seedling phase duration, and global warming impacts on forest species. Such models relate the physiological age of the plant, through air temperature functions, to its morphological appearance, given by the cumulative leaf number on the main stem. Despite their potential, studies on initial development dynamics are still scarce, especially for native forest species. Thus, this study calibrated and evaluated the performance of two development models—Phyllochron and Wang and Engel—in estimating the cumulative leaf number and seedling phase duration of two Brazilian native forest species—Cybistax antisyphilitica (Mart.) Mart. (Bignoniaceae) and Platycyamus regnellii Benth. (Fabaceae). Cumulative leaf number and seedling phase duration data from outdoor experiments carried out during the 2017 and 2018 growing seasons with 12 sowing dates in Itajubá, Minas Gerais, Brazil, were used. These experiments provided a rich dataset for calibrating and evaluating the Phyllochron and Wang and Engel development models. Both development models were capable of predicting cumulative leaf number with low and acceptable errors for both species and produced less accurate estimates for seedling phase duration. For C. antisyphilitica, both models were remarkably similar in estimating cumulative leaf number and seedling phase duration, with a root-mean-square error of 3.3 leaves and 25 days, respectively. For P. regnellii, the Wang and Engel model was slightly better than the Phyllochron, with an error of fewer than 2.06 leaves and 13.1 days. Using the coefficients calibrated in this study and, preferably, the Wang and Engel model, it is possible to project the development of both forest species under climate change scenarios.

Can morpho-physiological responses to natural light conditions in Cybistax antisyphilitica (Mart.) Mart. explain its widespread occurrence in Brazilian Savannas?

Cybistax antisyphilitica (Bignoniaceae) is extensively distributed in the Cerrado biome, from typical savannas to forest formations. In these areas, light varies widely in both time and space. The aim of this study was to investigate the initial growth and physiological responses of potted C. antisyphilitica seedlings to natural light conditions. To this end, we cultivated one group of seedlings under full sunlight (FS), a second group under a small gap with medium transmittance (MT) and a third group under canopy shade with low transmittance (LT), in an urban fragment of a tropical semideciduous forest. The daily course of chlorophyll a fluorescence was measured at the beginning, middle and end of the dry season. Also, at the end of the experiment, measurements of leaf gas exchange and growth were carried out. Dynamic photoinhibition was found in seedlings under FS. The photosynthetic rates, stomatal conductance and transpiration rates were higher under FS compared to seedlings under LT conditions. Overall, the stem diameter, the dry mass of leaves and stem, total dry mass and relative growth rate were higher in plants under FS and MT than plants under LT. Cybistax antisyphilitica allocated less biomass to stems and leaves and more to the roots, independent of growth conditions. The plasticity at leaf level suggests that C. antisyphilitica can exploit the heterogenous light environment of the semideciduous forest, but the massive development of the roots can contribute to its tolerance to dry periods typical of the Cerrado biome.

Initial growth crown cover of cerrado species from different sucessional groups

This study had the objective to evaluate the initial growth and crown cover of native cerrado species of different successional groups in planting forest restoration in Chapadão do Sul, MS, with an experiment installed in February of 2013 to test restoration models. Twelve species were selected, being four pioneers: Anadenanthera falcata, Cybistax antisyphilitica, Platypodium elegan and Samanea tubulosa; four early secondary species: Dipteryx alata, Sterculia striata, Alibertia edulis and Enterolobium contortisiliquum; and four late secondary species: Cedrela fissilis, Copaifera langsdorfii, Handroanthus roseo-albus and Hymenaea stilbocarpa. Diameter at soil height (DSH), total height and crown diameter were measured at 8, 14, 20 and 26 months after planting. the periodic increase in height and DSH were calculated by species, group and age, and the crown area at 26 months. The highest increases in height and DSH were from the pioneers group and from the early secondary until 26 months, and the lowest increases were from the late secondary species. The species within each group vary their initial investment in height and DSH. The pioneers group presented the largest crown areas, while the late secondary group presented the smallest.

Flora of Pernambuco, Brazil: Tabebuia alliance and tribe Jacarandeae (Bignoniaceae)

Abstract: Bignoniaceae is a Pantropical plant family that includes 82 genera and 830 species of trees, lianas, and shrubs. The Tabebuia alliance (14 genera and 147 species) and tribe Jacarandeae (2 genera and 50 species) are both Neotropical and represent the largest clades of trees and shrubs in the family. Here, we present a taxonomic treatment for these two clades for the state of Pernambuco, Brazil. Overall, we documented 23 species distributed in seven genera, i.e., Cybistax Mart. ex Meisn., Godmania Hemsl., Jacaranda Juss., Handroanthus Mattos, Sparattosperma Mart. ex Meisner, Tabebuia Gomes ex DC., and Zeyheria Mart. Six taxa are new records for the state, i.e., Cybistax antisyphilitica (Mart.) Mart., Handroanthus capitatus (Bureau & K. Schum) Mattos, Handroanthus umbellatus (Sond.) Mattos, Jacaranda cuspidifolia Mart., Sparattosperma catingae A.H. Gentry, and Tabebuia stenocalyx Sprague & Stapf. Furthermore, S. catingae, previously thought to be endemic to the Caatinga of Bahia, was documented for the first time in the Atlantic Forest domain. We present identification keys and taxonomic descriptions for all genera and species, as well as provide illustrations and information on the geographic distribution, habitat, and phenology for all species.

Comparative Ovule Ontogeny in Some Members of theTabebuiaAlliance (Bignoniaceae)

Premise of research. Recent phylogenetic studies placed nearly all Neotropical arboreal and shrubby species of the Bignoniaceae (excluding Jacaranda) in the Tabebuia alliance, a clade that includes all of the woody species in this family with palmately compound leaves. However, the taxa assigned to this clade have appeared in these studies as an unresolved trichotomy with Sparattosperma as its sister group. Considering the diversity and taxonomic significance of ovule morphogenesis in the extant angiosperms, this study aimed to contribute to the systematics of the Bignoniaceae by investigating ovule ontogeny in one representative of each clade of the Tabebuia alliance trichotomy: Crescentia cujete, Cybistax antisyphilitica, and Tabebuia roseoalba.Methodology. The analysis is based on light microscopy observations of microtome semiserial sections of ovaries and ovules at several stages of development.Pivotal results. The ovules are anatropous, unitegmic, and tenuinucellate and originate from trizonate ovul...

Validation of quality tests for forest seed species

The Brazilian literature on seed germination testing of tropical forest species, although still insufficient, is extensive for species with economical potential. However, this information is still fragmented and often reported in scientific communications of modest circulation. In this summary, we present the results of a validation process for germination tests on Brazilian forest species, which had as a starting point the ample reviewing of current methods, besides exhaustive pre-testing in certified laboratories. Specific protocols were created for each species, including substrate, temperature, seed disinfection, breaking of dormancy, seedling classification and other information. These protocols were sent to research laboratories and accredited by the Ministry of Agriculture, together with seed lots of three distinct qualities. The presuppositions of normality of the residuals and homoscedasticity of the variations were previously tested and the completely randomized factorial design statistical model was applied to the normal seedlings of each species. After this analysis, germination test methods for seeds of Astronium fraxinifolium, Ceiba speciosa, Cybistax antisyphilitica, Enterolobium contortisiliquum, Guazuma ulmifolia, Lafoensia pacari, Mimosa caesalpiniaefolia, Peltophorum dubium, Pseudobombax tomentosum and Pterogyne nitens, all forest species of different Brazilian biomes, were considered to be validated.

The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like “Cerrado” vegetation

Bignoniaceous woody species are very important ecological components of neotropical forests, but the reproductive biology of many species, such as Cybistax antisyphilitica, remains virtually unknown. Most species of Bignoniaceae are characteristically self-sterile, despite typically exhibiting normal pollen tube growth throughout the style, combined with slow rates of ovule penetration, fertilisation and endosperm initiation in selfed pistils. Uniform abortion occurs within a few days of anthesis, indicating the occurrence of late-acting self-incompatibility (LSI). However, breeding system studies have been performed in fewer than 7% of species, and other types of breeding systems (e.g., self-compatibility and apomixis) have been reported in this family. In the present study, the reproductive biology of C. antisyphilitica was investigated by field observation of flower visitors and floral events. Moreover, reproductive biology of this species was examined through experimental pollinations, analyses of pollen tube growth and ovule penetration using fluorescence microscopy, verification of pistil longevity, and a histological analysis of unpollinated vs. self-pollinated pistils. Finally, morphological aspects, quantities and germination were investigated in seeds that resulted from different pollination treatments. Natural pollination was effected by large- and medium-sized bees, and their visiting behaviour favours a high proportion of geitonogamy and no pollen limitation. Self-pollinated flowers produced no fruits, and all of the characteristic post-pollination events cited above were verified, witnessing the occurrence of LSI with post-zygotic rejection of selfed pistils in C. antisyphilitica. Although some indications of extended pistil longevity were found in selfed pistils, this feature seemed to be affected by unidentified environmental factors. The seeds were always monoembryonic and with high viability. A larger variation in the number of viable seeds was found in fruits derived from natural pollination. A low fruit set was observed after both natural and cross-pollination, and most crossed fruits underwent abortion at several points during the juvenile phase, even when protected against herbivory. The formation of surplus flowers/juvenile fruits and the apparently wasteful selfing mechanism control implied in LSI are discussed in the context of the perennial life style of tropical woody plant species.

LARVICIDAL ACTIVITY OF SOME CERRADO PLANT EXTRACTS AGAINST AEDES AEGYPTI

One hundred ninety hexanic and ethanolic extract from 27 plant species from the Cerrado biome of Brazil were tested for larvicidal activity against 3rd-stage Aedes aegypti larvae at 500 microg/ml. Fourteen extracts from 7 species showed activity (>65% mortality) against the larvae. Of these Dugeutia furfuracea, Piptocarpha rotundifolia, Casearia sylvestris var. lingua, Serjania lethalis, and Xylopia aromatica were active at 56.6, 162.31, 232.4, 285.76, and 384.37 microg/ml, respectively. Annona crassiflora and Cybistax antisyphilitica showed activity at 23.06 and 27.61 microg/ml. The larvicidal properties of these species are described for the first time, and may prove to be promising in active chemical compound isolation.

Larvicidal activity of Cybistax antisyphilitica against Aedes aegypti larvae

The larvicidal activity against Aedes aegypti larvae of a stem wood hexane extract of Cybistax antisyphilitica was evaluated. Bioassay-guided fractionation of the crude extract, monitored by larvicidal assay, led to the isolation of a natural quinone identified as 2-hydroxy-3-(3-methyl-2-butenyl)-1.4-naphthoquinone (lapachol). This compound was quite potent against A. aegypti larvae (LC 50 26.3 μg/ml).