Growth and production of Heliconia under different light conditions / Crescimento e produção de Helicônia sob diferentes condições de luminosidade

The use of shading screens of different colors can change the spectral quality of radiation and, as a consequence, the growth and production of crop plants. The aim of this study was to evaluate aspects of the growth, yield, and quality of floral stems of Heliconia psittacorum × H. spathocircinata ‘Golden Torch grown under different light conditions. The treatments consisted of four conditions: blue photoconversion screens (35%-40%); red photoconversion screens (18%-21%); black shading screens (45%-49%), and full sunlight. The experiment consisted of two parts. In the first, growth was assessed, whereas in the second, aspects related to the production and quality of floral stems were examined. The experimental design was in randomized blocks with split plots in time. Each plot contained six blocks, with 11 replications per block, giving a total of 66 pots per plot. The evaluations were performed at 30- day intervals over a 6-month period. In the analysis of growth, red screens contributed to the growth of the plants, increasing the number of shoots and leaves, and also plant height. The productivity and quality of floral stems was, however, highest in plants grown under blue and black screens. It can be concluded that, under the prevailing experimental conditions, the use of blue screens (35%-40%) and black screens (45%-49%) is suitable for production of the floral stems of ‘Golden Torch heliconia.(AU)

O uso de malhas de sombreamento de diferentes cores pode alterar a qualidade espectral da radiação e, como consequência, o crescimento e a produção de uma cultura vegetal. Desta forma, o objetivo do presente trabalho foi avaliar aspectos do crescimento, produção e qualidade das hastes florais de Heliconia psittacorum x H. spathocircinata ‘Golden Torch cultivadas sob diferentes condições de luminosidade. Os tratamentos consistiram em quatro ambientes: malha fotoconversora azul (35-40%); malha fotoconversora vermelha (18-21%); malha de sombreamento preta (45-49%) e pleno sol. O experimento constou de duas partes: na primeira realizaram-se avaliações de crescimento e na segunda, foram estudados aspectos relacionados à produção e qualidade das hastes florais. O delineamento experimental foi em blocos casualizados em esquema de parcelas subdivididas no tempo, sendo seis blocos por parcela, cada bloco com onze repetições, totalizando sessenta e seis vasos por parcela. As avaliações foram realizadas durante seis meses, com intervalos de trinta dias. Nas análises de crescimento observou-se que a malha vermelha contribuiu com o crescimento das plantas, incrementando o número de perfilhos, folhas e altura das plantas. A produtividade e a qualidade das hastes florais foi superior em plantas cultivadas sob tela azul e preta. Conclui-se que, nas condições experimentais estabelecidas, o uso das malhas azul (35-40%) e preta (45-49%) é indicado para a produção de hastes florais de Heliconia ‘Golden Torch.(AU)

Growth and production of Heliconia under different light conditions / Crescimento e produção de Helicônia sob diferentes condições de luminosidade

The use of shading screens of different colors can change the spectral quality of radiation and, as a consequence, the growth and production of crop plants. The aim of this study was to evaluate aspects of the growth, yield, and quality of floral stems of Heliconia psittacorum × H. spathocircinata ‘Golden Torch’ grown under different light conditions. The treatments consisted of four conditions: blue photoconversion screens (35%-40%); red photoconversion screens (18%-21%); black shading screens (45%-49%), and full sunlight. The experiment consisted of two parts. In the first, growth was assessed, whereas in the second, aspects related to the production and quality of floral stems were examined. The experimental design was in randomized blocks with split plots in time. Each plot contained six blocks, with 11 replications per block, giving a total of 66 pots per plot. The evaluations were performed at 30- day intervals over a 6-month period. In the analysis of growth, red screens contributed to the growth of the plants, increasing the number of shoots and leaves, and also plant height. The productivity and quality of floral stems was, however, highest in plants grown under blue and black screens. It can be concluded that, under the prevailing experimental conditions, the use of blue screens (35%-40%) and black screens (45%-49%) is suitable for production of the floral stems of ‘Golden Torch’ heliconia.

O uso de malhas de sombreamento de diferentes cores pode alterar a qualidade espectral da radiação e, como consequência, o crescimento e a produção de uma cultura vegetal. Desta forma, o objetivo do presente trabalho foi avaliar aspectos do crescimento, produção e qualidade das hastes florais de Heliconia psittacorum x H. spathocircinata ‘Golden Torch’ cultivadas sob diferentes condições de luminosidade. Os tratamentos consistiram em quatro ambientes: malha fotoconversora azul (35-40%); malha fotoconversora vermelha (18-21%); malha de sombreamento preta (45-49%) e pleno sol. O experimento constou de duas partes: na primeira realizaram-se avaliações de crescimento e na segunda, foram estudados aspectos relacionados à produção e qualidade das hastes florais. O delineamento experimental foi em blocos casualizados em esquema de parcelas subdivididas no tempo, sendo seis blocos por parcela, cada bloco com onze repetições, totalizando sessenta e seis vasos por parcela. As avaliações foram realizadas durante seis meses, com intervalos de trinta dias. Nas análises de crescimento observou-se que a malha vermelha contribuiu com o crescimento das plantas, incrementando o número de perfilhos, folhas e altura das plantas. A produtividade e a qualidade das hastes florais foi superior em plantas cultivadas sob tela azul e preta. Conclui-se que, nas condições experimentais estabelecidas, o uso das malhas azul (35-40%) e preta (45-49%) é indicado para a produção de hastes florais de Heliconia ‘Golden Torch’.

Interactions between plant size and canopy openness influence vital rates and life-history tradeoffs in two neotropical understory herbs.

UNLABELLED: • PREMISE OF THE STUDY: For tropical forest understory plants, the ability to grow, survive, and reproduce is limited by the availability of light. The extent to which reproduction incurs a survival or growth cost may change with light availability, plant size, and adaptation to shade, and may vary among similar species.• METHODS: We estimated size-specific rates of growth, survival, and reproduction (vital rates), for two neotropical understory herbs (order Zingiberales) in a premontane tropical rainforest in Costa Rica. During three annual censuses we monitored 1278 plants, measuring leaf area, number of inflorescences, and canopy openness. We fit regression models of all vital rates and evaluated them over a range of light levels. The best fitting models were selected using Akaike's Information Criterion.• KEY RESULTS: All vital rates were significantly influenced by size in both species, but not always by light. Increasing light resulted in higher growth and a higher probability of reproduction in both species, but lower survival in one species. Both species grew at small sizes but shrank at larger sizes. The size at which shrinkage began differed among species and light environments. Vital rates of large individuals were more sensitive to changes in light than small individuals.• CONCLUSIONS: Increasing light does not always positively influence vital rates; the extent to which light affects vital rates depends on plant size. Differences among species in their abilities to thrive under different light conditions and thus occupy distinct niches may contribute to the maintenance of species diversity.

Traditional and geometric morphometrics supporting the differentiation of two new Retracrus (Phytoptidae) species associated with heliconias.

Cryptic diversity has been confirmed for several phytophagous mites in the Eriophyoidea superfamily previously considered as presenting low host specificity. Among generalist eriophyoids is the phytoptid Retracrus johnstoni Keifer, which has been reported in 19 palm species belonging to 11 genera, causing severe damage on some of them. Surprisingly this species was recently reported on another monocot family, Heliconiaceae, infesting Heliconia plants in Costa Rica and Brazil, being the only in the tribe Mackiellini to not be associated with palm trees. This study aimed to investigate the occurrence of cryptic species in R. johnstoni and to clarify the taxonomic status of populations associated with heliconias in the Americas. With this purpose traditional and geometric morphometric analyses were conducted as well as a detailed morphological study. Measurable trait data were analysed via univariate and multivariate analyses. Shapes of specimens from different populations were compared via geometric morphometric landmark methods. Morphometric analysis supported occurrence of at least two cryptic species previously identified as R. johsntoni and suggested occurrence of cryptic species among populations associated with different palm trees. Taxonomic descriptions of two new taxa associated with heliconias, namely Retracrus costaricensis n. sp. Ferreira and Navia and Retracrus heliconiae n. sp. Ferreira and Navia are presented. Morphometric traits that can be useful in the taxonomic identification are noted and their value is discussed. Results of the traditional morphometry and geometric methods were compared and the advantages of their joint use for Eriophyoidea systematics are discussed.

Heliconia phenotypic diversity based on qualitative descriptors.

The aim of this study was to characterize Heliconia genotypes phenotypically using 26 qualitative descriptors. The evaluations were conducted in five flowering stems per clump in three replicates of 22 Heliconia genotypes. Data were subjected to multivariate analysis, the Mahalanobis dissimilarity measure was estimated, and the dendrogram was generated using the nearest neighbor method. From the values generated by the dissimilarity matrix and the clusters formed among the Heliconia genotypes studied, the phenotypic characterizations that best differentiated the genotypes were: pseudostem and wax green tone (light or dark green), leaf-wax petiole, the petiole hair, cleft margin at the base of the petiole, midrib underside shade of green, wax midrib underside, color sheet (light or dark green), unequal lamina base, torn limb, inflorescence-wax, position of inflorescence, bract leaf in apex, twisting of the rachis, and type of bloom. These results will be applied in the preparation of a catalog for Heliconia descriptors, in the selection of different genotypes with most promising characteristics for crosses, and for the characterization of new genotypes to be introduced in germplasm collections.

Edge effects on growth and biomass partitioning of an Amazonian understory herb (Heliconia acuminata; Heliconiaceae).

PREMISE: After deforestation, environmental changes in the remaining forest fragments are often most intense near the forest edge, but few studies have evaluated plant growth or plasticity of plant growth in response to edge effects. METHODS: In a 2-year common garden experiment, we compared biomass allocation and growth of Heliconia acuminata with identical genotypes grown in 50 × 35 m common gardens on a 25-year-old edge and in a forest interior site. KEY RESULTS: Genetically identical plants transplanted to the forest edge and understory exhibited different patterns of growth and biomass allocation. However, individuals with identical genotypes in the same garden often had very different responses. Plants on forest edges also had higher growth rates and increased biomass at the end of the experiment, almost certainly due to the increased light on the forest edge. CONCLUSIONS: With over 70000 km of forest edge created annually in the Brazilian Amazon, phenotypic plasticity may play an important role in mediating plant responses to these novel environmental conditions.

Tree species identity and interactions with neighbors determine nutrient leaching in model tropical forests.

An ecosystem containing a mixture of species that differ in phenology, morphology, and physiology might be expected to resist leaching of soil nutrients to a greater extent than one composed of a single species. We tested the effects of species identity and plant-life-form richness on nutrient leaching at a lowland tropical site where deep infiltration averages >2 m year(-1). Three indigenous tree species with contrasting leafing phenologies (evergreen, dry-season deciduous, and wet-season deciduous) were grown in monoculture and together with two other life-forms with which they commonly occur in tropical forests: a palm and a giant, perennial herb. To calculate nutrient leaching over an 11-year period, concentrations of nutrients in soil water were multiplied by drainage rates estimated from a water balance. The effect of plant-life-form richness on retention differed according to tree species identity and nutrient. Nitrate retention was greater in polycultures of the dry-season deciduous tree species (mean of 7.4 kg ha(-1) year(-1) of NO(3)-N lost compared to 12.7 in monoculture), and calcium and magnesium retention were greater in polycultures of the evergreen and wet-season deciduous tree species. Complementary use of light led to intensification of soil exploitation by roots, the main agent responsible for enhanced nutrient retention in some polycultures. Other mechanisms included differences in nutrient demand among species, and avoidance of catastrophic failure due to episodic weather events or pest outbreaks. Even unrealistically simple multi-life-form mimics of tropical forest can safeguard a site's nutrient capital if careful attention is paid to species' characteristics and temporal changes in interspecific interactions.

Developmental anatomy and morphology of the ovule and seed of heliconia (heliconiaceae, zingiberales).

The developmental anatomy and morphology of the ovule and seed in several species of Heliconia were investigated as part of an embryological study of the Heliconiaceae and to provide a better understanding of their relationships with the other families of the Zingiberales. Heliconia species have an ovule primordium with an outer integument of both dermal and subdermal origin. The archesporial cell is divided into a megasporocyte and a single parietal cell, which in turn are divided only anticlinally to form a single parietal layer, disintegrating later during gametogenesis. The embryo sac was fully developed prior to anthesis. In the developing seed, the endosperm was nuclear, with wall formation in the globular stage; a nucellar pad was observed during embryo development, but later became compressed. The ripe fruit contained seeds enveloped by a lignified endocarp that formed the pyrenes, with each pyrene having an operculum at the basal end; the embryo was considered to be differentiated. Most of these characteristics are shared with other Zingiberales, although the derivation of the operculum from the funicle and the formation of the main mechanical layer by the endocarp are unique to the Heliconiaceae.