SPAD-502 readings in response to photon fluence in leaves with different chlorophyll content

The chlorophyll meter (SPAD-502) is widely used to estimate chlorophyll content, but non-uniform chloroplast distribution can affect its accuracy. This study aimed to assess the effect of photon fluence (F, irradiance x time of illumination) in leaves with different chlorophyll content and determine the effect of chlorophyll a/b on SPAD values of four tropical tree species (Croton draconoides Müll. Arg., Hevea guianensis Aubl., Hymenaea courbaril L. and Matisia cordata H.B.K.). There were also determined calibration equations for the chlorophyll meter and assessed the effect of F on SPAD values between 07:00 h and 17:00 h. Calibration equations were obtained after determining leaf chlorophyll content in the laboratory. Increases in F with time caused a reduction in SPAD values in species with a high chlorophyll content, with reductions of 20% in M. cordata and 10% in H. guianensis. Leaves of C. draconoides and H. courbaril had lower chlorophyll content and showed no changes in SPAD values with increase in F. The chlorophyll a/b ratio increased with SPAD values and the SPAD/chlorophyll relationship was best described by an exponential equation. It seems that F may affect SPAD values in leaves with high chlorophyll content, probably due to non-uniform chloroplast distribution at high irradiance. This indicates that SPAD values tend to be more accurate if recorded early in morning when irradiance is low

Dissolved organic carbon concentration and its relationship to electrical conductivity in the waters of a stream in a forested Amazonian blackwater catchment

Background: Dissolved organic carbon (DOC) is a major component of the total carbon in headstreams in Amazonia. Long-term measurements of DOC concentration are difficult to obtain in remote areas of Amazonia. Aims: To take measurements of electrical conductivity (EC) and DOC concentration in a blackwater stream and to determine whether it is possible to make predictions of the DOC concentration in such streams using continuous measurements of EC alone. Methods: In a forested area, DOC concentration and EC were measured in groundwater along a topographic gradient at weekly intervals over a period of 8 months, and in stream water at half-hourly intervals over 2 years. Results: Strong and positive relationships between EC and DOC concentration were found in stream water in wet (r 2 = 0.99) and dry periods (r 2 = 0.97). It was thus possible to produce two equations that could be used to derive DOC concentration values from continuous measurements of EC. Both DOC concentration and EC varied according to the discharge, indicating that the largest amounts of DOC are transported during the wet season. The amount of carbon exported annually was estimated to be between 2.5% and 5% of the sink estimated by the eddy covariance method. Conclusions: The relationship found offers an opportunity for a comprehensive assessment of DOC concentration in blackwater catchments based on low-cost and simple EC measurements, rather than on expensive and complex estimates of DOC concentration. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis

Description of Immature Stages and Development Time of Paralucilia paraensis (Mello) (Diptera: Calliphoridae) Associated with the Decomposition of a Partially Submerged Swine Carcass

We report on the bionomics and morphology of the immature stages of Paralucilia paraensis (Mello) (Diptera: Calliphoridae). Observations were made on a daily basis for 10 h (from 8 a.m. to 6 p.m.) on a 45-kg pig (Sus scrofa) whose carcass had been partially submerged in a stream of water on the 21st of November 2009, in a forested area of Manaus, Amazonas, Brazil. The collected specimens were placed in plastic vials and transferred to a growth chamber maintained at room temperature. Adults of P. paraensis were collected on the carcass between the 3rd and the 18th days. A total of 13 gravid females were captured; from these, 1,240 eggs were obtained and yielded 1,030 larvae that developed into 879 adults. The average time required for hatching was 13 h. On average, the larvae reached the second instar within 13 h, third instar within 18 h, and pupae within 46 h. The pupal stage lasted 96 h. The complete development time was 216 h. This is the first report on the development time and morphology of immature stages of P. paraensis in forested areas. Therefore, these results provided information for the implementation of future forensic studies in the state of Amazonas

Asexual propagation of peach palm by division of the clump and extraction of the off-shoots Propagação assexuada em pupunheira por divisão da touceira variando o tempo de cicatrização dos perfilhos

The peach palm (Bactris gasipaes) is a native Amazonian palm tree that produces fruits and palm hearts, and is now attracting the interest of the farmers in other parts of Brazil given the economical potential of palm heart production. Traditionally the peach palm is propagated by seeds, which yield segregating progenies due to cross-pollination. To guarantee the uniformity and quality of elite selections, the alternative is the propagation of superior genotypes from off-shoots (tillers), because an efficient in vitro cultivation protocol does not exist. The objective of the present study was the development of a more appropriate technique of vegetative propagation by division of the clump, in order to multiply plants selected in the improvement program. A peach palm clump contains between 2 and 20 off-shoots after cutting for palm heart; these can be separated one from the other with iron wedges, and extracted immediately or left for recovery for subsequent extraction. The experimental design was randomized blocks with three replications, using a 3x5 factorial, where the factors were: height of the off-shoots (<30, 30-60, >60 cm) and recovery time after the separation of the off-shoots from the clump (0, 30, 60, 90 and 120 days). The off-shoots between 30 and 60 cm and left around a month of recovery in the field after separation from the clump presented 65% of survival, while those left around four months presented 80% of survival.<br>A pupunheira (Bactris gasipaes) é uma palmeira nativa da Amazônia que produz frutos e palmitos e, atualmente está despertando o interesse dos produtores rurais em outras partes do Brasil por seu potencial econômico para produção de palmito. O método de propagação tradicionalmente utilizado na pupunheira é por sementes, a qual apresenta segregação importante devido à polinização cruzada. O presente trabalho teve como objetivo o desenvolvimento de uma técnica mais apropriada de propagação da pupunheira por divisão de touceiras, para fins de multiplicação de plantas selecionadas no programa de melhoramento. Uma touceira de pupunha contem entre 2 e 20 perfilhos após manejo para palmito, que podem ser separados um do outro com o ferro de cova e extraídos imediatamente ou deixados para recuperação e posterior extração. O delineamento experimental foi de blocos ao acaso com três repetições, seguindo esquema fatorial 3x5, onde os fatores foram altura dos perfilhos (<30, 30-60 e >60 cm) e tempo de retirada dos perfilhos após a separação da touceira (0, 30, 60, 90 e 120 dias). Os perfilhos com altura entre 30 e 60 cm deixados por um mês de cicatrização no campo após a separação da touceira apresentaram sobrevivência de 65% e quando deixados por quatro meses apresentaram sobrevivência de 80%