Search

The luminous intensity is one of the limiting factors for the plant’s development, however, the existing information is based on observations on natural succession dynamics of tropical species, which are rarely studied as to their performance after planting. Thus, the present study aimed to answer: a) what is the performance of arboreal forest species (Inga vera, Schinus terebinthifolius, Handroanthus heptaphyllus, Parapiptadenia rigida, and Casearia sylvestris) after five years of planting, and what is the level of shading provided by these species in the subsoil? b) what is the behavior regarding survival, initial growth, and morphophysiological attributes of the species (Allophylus edulis, Cordia americana, Eugenia involucrata, and Psidium cattleianum) used in the enrichment of the underwood?, and c) indicate the best planting condition for the species studied, in degraded areas in the south of the Atlantic Forest Biome. We found that species described by their heliophilous behavior may be unsuitable for planting in full sun in degraded areas, as is the case with C. sylvestris. On the other hand, I. vera and S. terebinthifolius, have the potential for rapid growth in full sun, intermediate for H. heptaphyllus and P. rigida. Consequently, these species provided different shading after five years. Some species (A. edulis, C. americana, and E. involucrata) demonstrated that the morphophysiological performance was favored under shading of 76 and 80% (S. terebinthifolius and Inga vera, respectively). A. edulis and P. cattleianum were the species with the greatest assimilation of CO2, in the range of photosynthetically active radiation of 1500 mmol m-2s−1. Species with behavior similar to I. vera, S. terebinthifolius, A. edulis, P. cattleianum are appropriate to make up the group of framework species or fillers together, and to a lesser extent those similar to P. rigida and H. heptaphyllus. So, this will reduce the action of ecological filters, factors that act by selecting the species that will be a part of the ecosystem and determining the pace of restoration of ecological processes (biotic and abiotic), favoring the establishment of other species less tolerant of high soil and air temperatures. C. sylvestris, C. americana, and E. involucrata are typical species to compose the diversity group in restoration projects, as they are restricted to growth in full sun, but are important in enrichment. We found that the pattern of behavior of tree forest species, in the initial phase of growth in the field, must be known to accelerate the soil cover of the degraded area, easing ecological filters for recovery.

Agroforestry systems have emerged in agriculture as a more sustainable alternative to food and energy production and environment conservation, characterized by the coexistence of two or more species in the same cultivation area. Thus, this study aimed to assess the dynamics of solar radiation, radiation use efficiency, growth and productivity of black oats grown in agroforestry systems and in two crop years. For these ends, the study was conducted in the field in southern Brazil, in two growing seasons (2017 and 2018). The studied species were: Schizolobium parahybae, Peltophorum dubium, Parapiptadenia rigida, Eucalyptus urograndis. Samples were collected at different points in the understory and parameters evaluated were: absolute and relative growth rates, net assimilation rate, leaf weight ratio, leaf area ratio, specific leaf area, transmissivity of solar radiation, radiation use efficiency, crude protein content and the productive performance of black oats. The dynamics of solar radiation was modified by the canopy characteristics of the trees, with the highest transmissivity values obtained in the understory of Parapiptadenia rigida. Higher levels of shading reduced growth and yield, increased the radiation use efficiency, the number of stomata on the leaf surface and the crude protein content of black oats. The productive performance of black oats was significantly influenced by the forest species and crop years, with the highest productivity obtained in the P. rigida understory and in the crop year 2017. Based on the information generated in this study, the cultivation of black oats under P. rigida is highly recommended.

The development of effective silvicultural prescriptions for Atlantic forest secondary patches could offset the amount of exploitative logging in Amazonian forests. This study described the diameter growth response of Parapiptadenia rigida (Fabaceae), a dense wooded, fast-growing canopy tree, to liana competition in attempt to determine silvicultural prescriptions for this species in natural forests. Field procedures were carried out in one fragment of natural forest, in which one hundred 0.01 ha plots and 50 individual trees of the target species were selected. We found 23 species in the liana community, which was strongly dominated by Senegalia tucumanensis (Fabaceae). P. rigida had more lianas infesting it compared to the overall forest and its presence increased the abundance of S. tucumanensis. Trees with more than 50% of the crown occupied by lianas had a lower height:diameter ratio. Liana below-ground competition, measured by liana basal area around target trees, reduced diameter increment in P. rigida. The studied species showed great potential for timber production due to fast growth, wood quality and carbon sequestration. The developed individual tree diameter growth model shows that silvicultural treatments could increase diameter growth to about 1.5 cm/year.

Response to mineral fertilization and inoculation with rhizobia and/or arbuscular mycorrhiza fungi (AMF) of the Anadenanthera colubrina, Mimosa bimucronata and Parapiptadenia rigida (Leguminosae–Mimosoideae) native trees from Brazilian riparian forests, were studied in nursery conditions. Each species was submitted to seven treatments, varying nitrogen and phosphorous fertilization and inoculation with rhizobia (r), mycorrhiza (m) or both (rm): NP, P, P+r,P+rm, N, N+m and N+rm. Results showed that AMF inoculations did not enhance the mycorrhizal colonization, and P uptake was not sufficient to sustain good growth of plants. The level of P mineral added affected negatively the AMF colonization in A. colubrina and M. bimucronata, but not in P. rigida. Native fungi infected the three legume hosts. The absence of mineral N limited growth of A. colubrina and P. rigida, but in M. bimucronata the lack of N was corrected by biological nitrogen fixation. N mineral added inhibited the nodulation, although spontaneous nodulation had occurred in A. colubrina and M. bimucronata. Rhizobia inoculation enhanced the number of nodules, nitrogenase activity and leghemoglobin content of these two species. Thus, the extent of rhizobial and mycorrhizal symbiosis in these species under nursery conditions can affect growth and consequently the post-planting success.

This study reports the antimicrobial evaluation of the species most commonly used in Rio Grande do Sul (RS), the southernmost state of Brazil, for treating conditions likely to be associated with microorganisms. A four-stage process of documentation and evaluation was conducted: (a). review of RS ethnobotanical studies; (b). analysis of traditional uses; (c). literature survey on phytochemical and pharmacological data; (d). microbiological screening of selected plants. From the 149 species initially identified, 49 were cited as being used for microbial associated conditions in at least two other regions in RS, and 18 were further selected for screening. The crude methanol extract of these 18 plants were evaluated against seven microorganisms using the diffusion agar test. Extracts from Chaptalia nutans, Cordia monosperma, Echinodorus grandiflorus, Eugenia uniflora, Leonurus sibiricus, Luehea divaricata, Malva sylvestris, Ocotea odorifera, Parapiptadenia rigida, Pluchea sagittalis, Psidium cattleyanum and Senna neglecta were active against at least one microorganism. Although preliminary, these results are useful for rationalizing the use of medicinal plants in established systems of traditional medicine in primary health care.

The leguminous Acacia caven, Erythrina crista-galli, Enterolobium contortisiliquum, Prosopis affinis and P. nigra nodulated with rhizobial strains isolated from other legume trees; therefore they were considered to be promiscuous (poorly specific) for nodulation. Sesbania punicea and Parapiptadenia rigida did not nodulate with the different strains, indicating a significant specificity for nodulation. A. caven was promiscuous for nodulation and nodulated with both fast- and slow-growing strains of rhizobia and our data suggest that the most efficient strains would be fast-growing rhizobia. A. caven was specific for effectivity since the amount of N2 which was fixed markedly depended on the strain. The relative efficiency (RE) of 6 out of the 11 strains used was higher than 0.80, suggesting they had an active uptake hydrogenase. Ac5, a strain isolated from A. caven, exhibited the highest N2-fixing ability and highest NE (nodule efficiency) when inoculated on its host and also had the highest RE. Shoot dry weight and acetylene reducing activity (ARA) were significantly correlated with the amount of N2 fixed (determined by the total nitrogen difference method), indicating that any of these methods could be used for screening the strains according to their ability to fix N2. The relative efficiency was not correlated with any of these parameters.

A survey of the nodulating ability of 17 Uruguayan native and subspontaneous tree legumes has added Inga uraguensis to the list of legumes known to fix N 2 . Nodulation and N 2 fixation capability of the following species were confirmed: Acacia caven , Calliandra tweediei , Parapiptadenia rigida , Lonchocarpus nitidus , Erythrina crista-galli . Whereas A. caven bore many nodules in all soil types observed, Prosopis nigra and P. affinis were always poorly nodulated. Seedlings of E. crista-galli bore aerial nodules at the base of their stem when grown in waterlogged conditions. The morphology, structure and nitrogenase activity (ARA) of the aerial nodules were similar to root nodules. Nodulation ability of Geoffroea decorticans was not confirmed. The species belonging to the Caesalpinoideae sub-family did not nodulate and were unable to do so even when they were inoculated with a mixture of rhizobia strains, thus confirming previous observations. Nodule morphology was described according to Corby's classification. Anatomical studies showed the presence of spaces in the inner zone of A. caven nodules. E. crista-galli and Enterolobium contortisiliquum nodules exhibited several infected zones, probably related to the coralloid morphology of the nodules. The acetylene-reducing activity of the nodules of the different species was generally low. Rhizobial strains were isolated from the most active nodules for future investigations.