Ajuste del coeficiente basal de cultivo (Kcb) de frijol (Phaseolus vulgaris) mediante teledetección

Para realizar un manejo eficiente del agua en la agricultura es necesario conocer los requerimientos hídricos del cultivo, lo cual, se puede realizar de manera sencilla y rápida, con la ayuda de cámaras convencionales. En este estudio, se determinaron los requerimientos hídricos de un cultivo de frijol (variedad DIACOL CALIMA G4494), sembrado en CIAT, Palmira - Valle del Cauca, Colombia, mediante la estimación de la curva del coeficiente basal de cultivo (Kcb), derivada de la curva de fracción de cobertura vegetal (Fcv). Para determinar la curva de fracción de cobertura vegetal, se emplearon imágenes tomadas con una cámara digital en el espectro visible (RGB), a baja altura (menos de 3 m). Las necesidades hídricas del cultivo de frijol, se calcularon empleando los valores del coeficiente basal de cultivo derivados junto con la modelación FAO-56. Los resultados indican que la curva de Kcb ajustada por fotografía fue diferente a la curva estándar presentada en la publicación FAO-56 para frijol, mostrando, principalmente, diferencia en la duración de las etapas y los valores de Kcb, en estas etapas. En cuanto a las necesidades hídricas, al emplear la curva de Kcb ajustada por fotografías, se evidencia que el cultivo requiere más agua en las etapas media y final, para evitar estrés hídrico en las plantas.

To carry out efficient water management in agriculture, it is necessary to know the water requirements of the crop, which can be done easily and quickly with the help of conventional cameras. In this study, the water requirements of a bean crop (DIACOL CALIMA G4494 variety) planted in CIAT, Palmira - Valle del Cauca, Colombia, were determined by estimating the curve of the basal crop coefficient (Kcb) derived from the vegetation cover fraction curve (Fcv). To determine the vegetation cover fraction curve, images taken with a digital camera in the visible spectrum (RGB) at low height (less than 3m) were used. The water needs of the bean crop were calculated using the basal crop coefficient values derived together with the FAO-56 modelling. The results indicate that the Kcb curve adjusted by photography was different from the standard curve presented in the publication FAO-56 for beans, mainly showing a difference in the duration of the stages and the Kcb values in these stages. Regarding water needs, when using the Kcb curve adjusted by photographs, it is evident that the crop requires more water in the middle and final stages, to avoid water stress in the plants.

Diversidad y estructura de la comunidad de briófitos asociada con el helecho Asplenium auritum (Aspleniaceae) en un fragmento del bosque atlántico brasileño

Introducción: Los filtros ambientales locales ejercen influencia en la diversidad y en la estructura de las comunidades de briófitas, pero existen pocos estudios que analicen cómo las relaciones bióticas influyen en estas comunidades. Objetivo: Evaluar la influencia de la cobertura del helecho Asplenium auritum sobre los cambios en la riqueza de especies y la composición de las comunidades briófitos, en un bosque remanente semideciduo en Minas Gerais, Brasil. Métodos: Seleccionamos un transecto de 300 m en cada una de las seis áreas donde A. auritum estaba presente. En cada transecto, estimamos la cubierta vegetal en 39 parcelas de 10 × 10 cm distribuidas al azar. Comparamos la riqueza estimada de especies y la composición de briófitos entre los niveles de cobertura del helecho. Resultados: Encontramos 60 especies en 35 géneros y 23 familias. Las formas de vida más representativas fueron las de tipo trama y estera. Los diferentes niveles de cobertura del helecho no mostraron efecto significativosobre la riqueza de especies y la composición de las comunidades de briófitos. Conclusiones: La cobertura de briófitos parece favorecer el desarrollo del helecho, podría promover la coexistencia de varias especies de briófitos y podría predecir variaciones en la riqueza de especies e impulsar el ensamble de especies en esta comunidad.

Introduction: Local environmental filters have shown the influence on the bryophyte diversity and structure communities, but there are limited studies that analyze how biotic relationships filters influence these communities. Objective: To evaluate whether the influence of fern Asplenium auritum cover determine changes in species richness and composition of bryophyte communities, in a semideciduous remnant forest, Minas Gerais, Brazil. Methods: We selected one transect of 300 m in each of six areas where Asplenium auritum was present. In all transect we estimated plant cover in 39 10 × 10 cm plots randomly distributed. We compare the estimated species richness and composition of bryophyte between fern coverage levels. Results: We found 60 species in 35 genera and 23 families. Weft and mat were the most represented life-forms. Fern cover had no significant effect on bryophyte species richness and composition. Conclusions: Bryophyte cover appears to improve fern development and promote the coexistence of several bryophyte species. Bryophyte cover probably predicts variations in species richness and drives the species assemblage in this community.

Micronutrients content in Pueraria phaseoloides L. on soils under oil palm plantations in Tailândia, state of Pará / Acúmulo de micronutrientes em Kudzu tropical (Pueraria phaseoloides L) em solos sob plantações de dendê em Tailândia ­ Pará

The adoption of cover crops in commercial plantations has been shown to be an alternative to promote greater soil protection, enhancement in its structure and aggregation, optimization of accumulation and nutrient cycling to obtain greater production of biomass and higher nitrogen fixation. To determine the accumulation of micronutrients of Pueraria phaseoloides L., according to age, established as a soil cover in industrial oil palm crops, an experiment was carried out at Companhia Agroindustrial (CRAI) in the municipality of Tailândia, State of Pará, in an Oxisol. The experimental design was a randomized block with four replicates. The results allow to conclude that the accumulation of nutrients, except for Mn and Cu in the live Pueraria phaseoloides L. plant cover reduced over the years and those of B, Mn, Zn, and Cu were greater in the dead Pueraria phaseoloides L. plant cover and for Cl it was in the live Pueraria phaseoloides L. plant cover. The decreasing order of total micronutrient extraction was the following: Cl> Mn> B> Zn> Cu.

A adoção de plantas de cobertura em plantios comerciais tem se mostrado uma alternativa para promover ao solo maior proteção, melhorias em sua estrutura e agregação e otimização de acúmulo e ciclagem de nutrientes visando maior produção de biomassa e maior fixação de N2. Com o objetivo de determinar o acúmulo de micronutrientes puerária (Pueraria phaseoloides L.), em função da idade, estabelecida como cobertura de solo em plantações industriais de dendezeiros, instalou-se experimento na Companhia Real Agroindustrial (CRAI) no município de Tailândia, Estado do Pará, em Latossolo Amarelo. O delineamento experimental foi o de blocos ao acaso com quatro repetições. Os resultados permitem concluir que: o acúmulo de nutrientes com exceção do Mn e Cu na cobertura verde de Pueraria phaseoloides L., reduziu com o decorrer dos anos; os de B, Mn, Zn e Cu foram maiores na cobertura morta, enquanto que o de Cl na cobertura verde. A ordem decrescente da extração total de micronutrientes foi: Cl > Mn > B > Zn > Cu.

Environmental variables and tree population structures in deciduous forests of central Brazil with different levels of logging

Population structures of six tree species in three fragments of intact seasonal deciduous forest and three fragments disturbed by logging were studied in the northeastern Goiás. Forty random 400 m² plots were allocated in each fragment to survey plant population structures, number of stumps, cattle feces, burnt logs, and canopy openness. Soil cover by life forms was estimated in 1m² sub-plots. Lianas were abundant in intermediately logged fragments and invasive herbs in the most disturbed fragment. Cattle avoided dense herbaceous strata, such as liana tangles. Cavanillesia arborea, Eugenia dysenterica and Swartzia multijuga trees occurred at very low densities in all the fragments and their seedlings were practically absent, which might endanger their future populations in these fragments. Myracrodruon urundeuva, Tabebuia impetiginosa and Astronium fraxinifolium, the most logged species, had high density of seedlings in all the fragments. However, the highest density of saplings and juvenile individuals occurred in the most disturbed fragment.

As estruturas populacionais de seis espécies de árvores foram estudadas em três fragmentos de floresta estacional decidual intactos e três fragmentos impactados pela exploração seletiva de madeira no nordeste goiano. Quarenta parcelas de 400m² foram estabelecidas em cada fragmento para a amostragem de populações, número de tocos, fezes de gado, troncos queimados e abertura de dossel. A cobertura do solo por formas de vida foi estimada em sub-parcelas de 1m². Lianas foram mais abundantes em fragmentos com perturbação intermediária, enquanto herbáceas invasoras no fragmento mais perturbado. Cavanillesia arborea, Eugenia dysenterica e Swartzia multijuga ocorreram em densidades muito baixas em todos os fragmentos e plântulas foram praticamente ausentes, o que pode ameaçar o futuro de suas populações. Myracrodruon urundeuva, Tabebuia impetiginosa e Astronium fraxinifolium, as espécies mais exploradas da região, tiveram alta densidade de plântulas em todos os fragmentos. Entretanto, a maior densidade de plântulas estabelecidas (>1 ano) e juvenis ocorreu no fragmento mais perturbado.