Growth, leaf and stomatal traits of crabwood (Carapa guianensis Aubl.) in central Amazonia

Crabwood (Carapa guianensis Aubl.) is a fast growing tree species with many uses among Amazonian local communities. The main objective of this study was to assess the effect of seasonal rainfall pattern on growth rates, and seasonal and diurnal changes in leaf gas exchange and leaf water potential (ΨL) in crabwood. To assess the effect of rainfall seasonality on growth and physiological leaf traits an experiment was conducted in Manaus, AM (03º 05' 30" S, 59º 59' 35" S). In this experiment, six 6-m tall plants were used to assess photosynthetic traits and ΨL. In a second experiment the effect of growth irradiance on stomatal density (S D), size (S S) and leaf thickness was assessed in 0.8-m tall saplings. Stomatal conductance (g s) and light-saturated photosynthesis (Amax) were higher in the wet season, and between 09:00 and 15:00 h. However, no effect of rainfall seasonality was found on ΨL and potential photosynthesis (CO2-saturated). ΨL declined from -0.3 MPa early in the morning to -0.75 MPa after midday. It increased in the afternoon but did not reach full recovery at sunset. Growth rates of crabwood were high, and similar in both seasons (2 mm month-1). Leaf thickness and S D were 19% and 47% higher in sun than in shade plants, whereas the opposite was true for S S. We conclude that ΨL greatly affects carbon assimilation of crabwood by reducing g s at noon, although this effect is not reflected on growth rates indicating that other factors offset the effect of g s on Amax.

Estimation of weed dry biomass and grain yield as a function of growth and yield traits under allelopathic weed management in maize

Growing concerns about toxicity and development of resistance against synthetic herbicides have demanded looking for alternative weed management approaches. Allelopathy has gained sufficient support and potential for sustainable weed management. Aqueous extracts of six plant species (sunflower, rice, mulberry, maize, brassica and sorghum) in different combinations alone or in mixture with 75% reduced dose of herbicides were evaluated for two consecutive years under field conditions. A weedy check and S-metolachlor with atrazine (pre emergence) and atrazine alone (post emergence) at recommended rates was included for comparison. Weed dynamics, maize growth indices and yield estimation were done by following standard procedures. All aqueous plant extract combinations suppressed weed growth and biomass. Moreover, the suppressive effect was more pronounced when aqueous plant extracts were supplemented with reduced doses of herbicides. Brassica-sunflower-sorghum combination suppressed weeds by 74-80, 78-70, 65-68% during both years of study that was similar with S-metolachlor along half dose of atrazine and full dose of atrazine alone. Crop growth rate and dry matter accumulation attained peak values of 32.68 and 1,502 g m-2 d-1 for brassica-sunflower-sorghum combination at 60 and 75 days after sowing. Curve fitting regression for growth and yield traits predicted strong positive correlation to grain yield and negative correlation to weed dry biomass under allelopathic weed management in maize crop.

Distyly and variation in floral traits in natural populations of Psychotria ipecacuanha (Brot.) Stokes (Rubiaceae)

Psychotria ipecacuanha is a perennial, medicinal herb that grows in clusters in the understory of humid, shady areas of the Atlantic Rain Forest of southeastern Brazil. The present study characterized the variation in floral traits among 35 clusters from three natural populations of this plant species. Field observations showed that the clusters are isomorphic, that is, a given cluster will either set long-styled or short-styled flowers. Stigmas and anthers are reciprocally placed in each morph, a dimorphism characteristic of distyly. The populations are isoplethic, that is, a given population exhibits an equilibrium 1:1 ratio of floral morphs. Morphometric analyses revealed that anther length, stigma length, corolla diameter, and pollen grain diameter were consistently greater in short-styled flowers, regardless of the population investigated. Significant differences for floral traits in the short-styled morph were found among populations. Floral traits in the long-styled morph also showed some significant differences among populations, but not for stigma height and corolla length. Controlled pollinations carried out in natural populations showed that fruit production was higher after inter-morph pollination. Nevertheless, observations of pollen tube growth in style, and also fruit production after spontaneous self-pollination and intra-morph pollination, indicated partial intramorph compatibility in this plant species.

Personality traits and psychiatric comorbidities in alcohol dependence

Non-adaptive personality traits may constitute risk factors for development of psychiatric disorders such as depression and anxiety. We aim to evaluate associations and the predictive value of personality traits among alcohol-dependent individuals, with or without psychiatric comorbidities. The convenience sample comprised two groups of males over 18 years of age: one with subjects who had an alcohol dependence diagnosis (AG, n=110), and a control group without abuse and/or alcohol dependence diagnosis (CG, n=110). The groups were assessed by means of the Structured Clinical Interview DSM-IV (SCID-IV). AG participants were recruited among outpatients from the university hospital, whereas CG participants were recruited from a primary healthcare program. Data collection was done individually with self-assessment instruments. Parametric statistics were performed, and a significance level of P=0.05 was adopted. A positive correlation was observed between openness and the length of time that alcohol has been consumed, as were significant and negative correlations between conscientiousness and both the length of time alcohol has been consumed and the number of doses. For alcoholics, extraversion emerged as a protective factor against depression development (P=0.008) and tobacco abuse (P=0.007), whereas openness worked as a protective factor against anxiety (P=0.02). The findings point to specific deficits presented by alcoholics in relation to personality traits with or without psychiatric comorbidities and to the understanding that therapeutic approaches should favor procedures and/or preventive measures that allow more refined awareness about the disorder.

Effects of genotype and environment on grain yield and quality traits in bread wheat (T. aestivum L.)

Genotype (G), environment (E) and their interaction (GEI) play an important role in the final expression of grain yield and quality attributes. A multi-environment trial in wheat was conducted to evaluate the magnitude of G, E and GEI effects on grain yield and quality of wheat genotypes under the three rainfed locations (hereafter environment) of Central Anatolian Plateau of Turkey, during the 2012-2013 cropping season. Grain yield (GY) and analyses of test weight (TW), protein content (PC), wet gluten content (WGC), grain hardness (GH), thousand kernel weight (TKW) and Zeleny sedimentation volume (ZSV) were determined. Allelic variations of high and low molecular weight glutenin subunits (HMW-GS and LMW-GS) and 1B/1R translocation were determined in all genotypes evaluated. Both HMW-Glu-1, 17+18, 5+10 and LMW-Glu-3 b, b, b corresponded to genotypes possessing medium to good quality attributes. Large variability was found among most of the quality attributes evaluated; wider ranges of quality traits were observed in the environments than among the genotypes. The importance of the growing environment effects on grain quality was proved, suggesting that breeders' quality objectives should be adapted to the targeted environments.