AVALIAÇÃO FITOSSOCIOLÓGICA DE UM FRAGMENTO FLORESTAL EM ÁREA URBANA NA TRANSIÇÃO CERRADO – FLORESTA AMAZÔNICA

We aim to evaluate the floristic composition of an urban open ombrophilous forest fragment located in transition between Cerrado and Amazon Forest. The study was carried out in an urban open ombrophilous forest fragment located in the state of Maranhão, northeast Brazil. Fourteen 10 x 50 m plots were established: seven edge plots and seven core plots. We surveyed 394 trees with diameter at breast height ≥ 10 cm, belonging to 55 species and 26 families. The most representative families were Fabaceae, Arecaceae, Malvaceae, Annonaceae, and Bignoniaceae. Attalea speciosa occurred in all plots. The cluster analysis suggesting a reasonable similarity between the edge and core plots. Our results show that the fragment contains a transitional plant community of the Cerrado and Amazon Forest. Our findings suggest the plant community is in early to intermediate successional stage.O objetivo do estudo foi avaliar a composição florística de um fragmento de floresta ombrófila aberta urbana localizado na transição entre o Cerrado e a Floresta Amazônica. O estudo foi realizado em um fragmento urbano aberto de floresta ombrófila localizado no estado do Maranhão, Nordeste do Brasil. Quatorze parcelas de 10 x 50 m foram estabelecidas: sete parcelas de borda e sete parcelas de núcleo. Foram levantadas 394 árvores com diâmetro à altura do peito ≥ 10 cm, pertencentes a 55 espécies e 26 famílias. As famílias mais representativas foram Fabaceae, Arecaceae, Malvaceae, Annonaceae e Bignoniaceae. Attalea speciosa ocorreu em todas as parcelas. A análise de agrupamento sugeriu uma similaridade razoável entre os gráficos de borda e núcleo. Nossos resultados mostram que o fragmento contém uma comunidade de plantas de transição do Cerrado e da Floresta Amazônica e que a comunidade de plantas está em um estágio sucessional intermediário.   Palavras-chave: fitogeografia; riqueza florística; floresta ombrófila aberta; Amazônia legal.   Phytosociological evaluation of an urban forest fragment in a Cerrado - Amazon Forest transition   ABSTRACT: We aim to evaluate the floristic composition of an urban open ombrophilous forest fragment located in transition between Cerrado and Amazon Forest. The study was carried out in an urban open ombrophilous forest fragment located in the state of Maranhão, Northeast Brazil. Fourteen 10 x 50 m plots were established: seven edge plots and seven core plots. We surveyed 394 trees with diameter at breast height ≥ 10 cm, belonging to 55 species and 26 families. The most representative families were Fabaceae, Arecaceae, Malvaceae, Annonaceae, and Bignoniaceae. Attalea speciosa occurred in all plots. The cluster analysis suggesting a reasonable similarity between the edge and core plots. Our results show that the fragment contains a transitional plant community of the Cerrado and Amazon Forest. Our findings suggest the plant community is in early to intermediate successional stage. Keywords: phytogeography; floristic richness; open ombrophilous forest; Amazon legal

A threatened new species of Ipomoea (Convolvulaceae) from the Brazilian Cerrado revealed by morpho-anatomical analysis

A new species of Ipomoea, endemic to the Cerrado domain in Maranhão, Brazil, is described. Ipomoea maranhensis D.Santos & Buril, sp. nov. has been misidentified as I. burchellii Meisn. in several herbaria. Even though both species have oblong, pubescent leaves, they can be distinguished by morpho-anatomical characters. We present a diagnosis, complete description, illustration, taxonomic comments, conservation status and distribution map

Effects of indol butyric acid concentration on propagation from cuttings of papaya cultivars ‘Golden’ and ‘Uenf/Caliman 01’

Introduction. Papaya is one of the very few fruit crops multiplied by seed. Unfortunately, the use of seedlings hampers the preservation of favorable plant characteristics and delays the appearance of the first flowers. In addition, the polygamous nature of papaya imposes planting 3-4 seedlings per hole in order to be certain of obtaining the right sex type. These shortcomings can be circumvented by clonal multiplication. This work aimed to multiply selected papaya cultivars from cuttings using the rooting promoting auxin indole-3-butyric acid (IBA). Materials and methods. Two experiments were conducted; the first one followed a completely randomized factorial design, with cultivars ’Golden’ and ‘Uenf/Caliman 01’ as levels of the first factor, and 0, 500, 1,000, 1,500, and 2,000 ppm IBA as levels of the second factor. In this first trial, rooted cuttings of ‘Uenf/Caliman 01’ were taken to the field and compared to seedlings soon after planting and 4.5 months later. In the second experiment, IBA levels were increased aiming to enhance rooting percentage. Physiological assessments of rooted cuttings were also performed in this second experiment. Results and discussion. A concentration of 3,000 ppm IBA gave the best results for ‘Golden’, while lower concentration (1,500 ppm) seemed indicated for ‘Uenf/Caliman 01’. Rooting success in ‘Uenf/Caliman 01’ was improved by using cuttings obtained from beheaded mother plants. The analyses showed that a few roots were sufficient to maintain good water status and photosynthetic rate in new plantlets. Conclusion. Plants propagated from cuttings had early flowering and produced first fruits at a lower height than seedlings in the field

Aplicação foliar de silício em plantas jovens de cacau submetidas à deficiência hídrica

The objective of this work was to evaluate the physiological and anatomical traits of plants of a cacao (Theobroma cacao) clone in response to water deficit after leaf application of silicon. A randomized complete block design was used, with four replicates, in a 2x3 factorial arrangement of two water regimes (irrigated or nonirrigated) and three silicon concentrations (0.0, 1.5, and 3.0 mg mL-1) applied in wettable SiO2 powder. The plants were evaluated 20 days after the irrigation regimes were applied. The use of SiO2 increased the stability of cell membranes and the photochemical efficiency of the plants under water deficit. The 1.5 mg mL-1 concentration of SiO2 increased photosynthetic rate, water use efficiency, and carboxylation efficiency, besides mitigating the effect of oxidative stress. Stomatal density was reduced in nonirrigated plants under the highest concentration of Si. The 1.5 mg mL-1 concentration of Si is considered optimal for the photosynthetic metabolism of young cacao plants under soil water limitation.O objetivo deste trabalho foi avaliar as características fisiológicas e anatômicas de plantas de um clone de cacau (Theobroma cacao) em resposta ao deficit hídrico após a aplicação foliar de silício. Utilizou-se o delineamento de blocos ao acaso, com quatro repetições, em arranjo fatorial 2x3, com dois regimes hídricos (irrigado e não irrigado) e três concentrações de silício (0, 1,5 e 3,0 mg mL-1) aplicadas como pó molhável de SiO2. As plantas foram avaliadas 20 dias após a aplicação dos regimes de irrigação. O uso de SiO2 aumentou a estabilidade das membranas celulares e a eficiência fotoquímica das plantas sob deficit hídrico. A concentração de 1,5 mg mL-1 de SiO2 aumentou a taxa fotossintética, a eficiência do uso da água e a taxa de carboxilação, além de ter mitigado o efeito do estresse oxidativo. A densidade estomática foi reduzida em plantas não irrigadas sob a maior concentração de Si. A concentração de 1,5 mg mL-1 de Si é considerada ótima para o metabolismo fotossintético de plantas jovens de cacau sob limitação de água no solo

Photosynthetic capacity of 'Niagara Rosada' grapes grown under transparent plastic covering

ABSTRACT: New techniques in tropical regions such as use of transparent plastic covering (TPC), have been employed in grapes to avoid the wetting leaves and fruits, which can reduce the occurrence of fungal diseases, reduce the use of sprays, and reduce damage caused by hail and high winds. TPC may significantly affect the photosynthetic rates of grapevines cultivated in tropical regions, and thus have strong effects on plant productivity and improve fruit quality. However, in the North of Rio de Janeiro region there are lacks of studies related to TPC effects on photosynthetic capacity. The objective of this study was to evaluate the photosynthetic capacity in 'Niagara Rosada' vines grown under TPC and without transparent plastic covering (WTPC). The experiment was conducted between April and June 2013, on Tabuinha farm, located in the 3rd district of São Fidélis, Rio de Janeiro State, Brazil. A completely randomized block design was used with two treatments (TPC and WTPC) and twelve replications. Evaluations consisted of climatological variables, gas exchange and maximum quantum efficiency of open photosystem II centers-quantum yield (Fv/Fm) It was possible to observe that under TPC maximum temperature increase of 2.3°C, relative humidity reduced 1.5%, vapor pressure deficit increase 0.4kPa, and light intensity reduced 47.7%. These changes did not cause photochemical damage to the leaves. The TPC promoted higher net photosynthetic rate at 800h, which was associated with higher stomatal conductance. Thus, the TPC used in the northern region of Rio de Janeiro State did not impair the photosynthetic capacity of 'Niagara Rosada' vines