Observations of daytime surface energy balance in cloudy tropical conditions at Ile-Ife, Nigeria

Daytime energy balance at the surface in cloudy tropical conditions for Ile-Ife; Nigeria (7°33'N, 4°34'E) is investigated based on a series of micrometeorological measurements performed in October/November of 1998. For the humid environment that it is (mixing ratio, 17 -25 g / kg), magnitudes of the latent heat flux were much larger than the values for the sensible heat. Of the morning hours the average value for the Bowen ratio obtained was 0.36, while for the afternoons it was 0.74. As the soil surface became dried up in the afternoons, magnitudes of both sensible heat and ground heat fluxes were found to be comparable. Fluctuations in the magnitudes of the terms of the surface energy balance correlated well to the cloud amount, degree of soil wetness, air temperature and humidity. But of all these factors, the variation in the amount of cloudiness appeared most dominant.

Path-coefficient and correlation analysis in Bambara groundnut (Vigna subterranea [L.] Verdc.) accessions over environments

In a breeding program, studies of genotypic and phenotypic relationships among agricultural crop traits are useful to design, evaluate, and develop selection criteria for desirable traits. Using path coefficient analysis, the present study was executed to estimate the phenotypic, genotypic, and environmental correlation coefficients between yield and yield-related traits and to determine the direct and indirect effects of yield-related traits on yield per plant. A total of 30 genotypes of Vigna subterranea were studied under tropical conditions at two sites over two planting seasons (considered as four environments). The experiment at each site used a randomized complete block design with three replicates. Data were collected on vegetative and yield component attributes. Based on analysis of variance, pooled results showed that there were positive and highly significant differences (p ≤ 0.01) among the 30 genotypes for all attributes studied. Highly significant and positive strong correlation at phenotypic level was observed for dry seed weight (0.856), hundred seed weight (0.754), fresh pod weight (0.789), and total pod weight (0.626) with yield in kg per hectare, while moderate positive correlations were observed for harvest cut (0.360) and days to maturity (0.356). However, a perfect positive correlation was observed for the dry weight of pods with seed yield. In contrast, days to 50% flowering (− 0.350) showed a negative significant relationship with yield per hectare. The dried pod weight attribute (1.00) had a high positive direct effect on yield. Fresh pod weight had the greatest indirect effect on yield per hectare, followed by the number of total pods by dry pod weight. As a result, dry pod weight, hundred seed weight, number of total pods, and fresh pod weight could be used as selection criteria to improve the seed yield of Bambara groundnut (Vigna subterranea).

Control solar en envolvente vidriada tropical para mejorar el desempeño energético-ambiental por climatización

Con el objetivo de fundamentar la estrategia de control solar como propuesta efectiva en la rehabilitación energética de un edificio de oficinas de los años 50´s, se realiza un diagnóstico del comportamiento de la demanda energética por climatización debido a su fenestración translúcida. Para el estudio se modelan los tipos de espacios más comunes (con una, dos o tres fachadas de vidrio) los cuales son objeto de simulaciones horarias que permiten pronosticar la demanda de energía anual para enfriamiento. Además, se determina el impacto ambiental que provoca este tipo de carpintería en las condiciones tropicales, de alta incidencia solar y de producción de energía de Cuba. Se utiliza Energy Plus, el motor más reconocido y avanzado de Simulación Energética de Edificios, desarrollado por el Departamento de Energía de los EEUU. Fundamentadas en los resultados se realizan y evalúan dos propuestas de diseño de control solar en las fachadas sureste y suroeste, las cuales demuestran su efectividad a partir del ahorro pronóstico anual de energía eléctrica por climatización consecuencia del recurso de sombreado. También se demuestra la influencia de la orientación en el diseño de los elementos componentes de la envolvente vertical para favorecer, con su especificidad local, la eficiencia energética, la identidad; así como la cultura energética convocada por la dirección de la nación. In order to justify the strategy of solar control like effective proposal in the energetic rehabilitation of an office building of the years 50 ´s. This paper present a diagnosis of the behavior of the cooling energetic demand due to its glazed windows. For the study are modeled the types of spaces more common of the building (with one, two or three glass facades) which are simulated each one hour to predict the annual energy demand for cooling. In addition, the environmental impact is determined that causes this window type in the tropical conditions, of high solar incidence and dependence of fuels imported for the energy generation in Cuba. It is used Energy Plus the most advanced motor in Energy Simulation of Buildings, developed by U.S. Department of Energy Building Technologies Office. Based in the results are carried out and evaluate three designs of solar control in the facades southeast and southwest, which demonstrate their effectiveness in the saving annual of electric power for cooling. The results demonstrate the influence of the orientation in the design of the vertical envelope component elements to favor, with their local specificity, the energy efficiency and the identity, as well as the energetic culture convoked by the government of the nation.

Severity of clubroot in kale related to management practices and soil attributes

ABSTRACT: Clubroot disease, caused by Plasmodiophora brassicae, limits the production of Brassica spp. worldwide. Little is known about the factors related to the development of the disease in kale (Brassica oleracea var. acephala) plants and in crops in mountainous areas under tropical conditions. This study examined the severity of clubroot in kale crops as well as identify potential flaws in management and the soil and relief factors related to its occurrence. The study was conducted in 24 kale fields in the mountainous region of Rio de Janeiro (Brazil). Soil and kale growth management practices adopted in the region were identified and samples of soil and plants were collected. Subsequently, soil and relief attributes, disease severity, biomass and nutrient and Al contents and accumulation in the plants were determined. There was a high spread of the pathogen in the areas. Inappropriate and recurrent practices in the region were detected, e.g., sequential cultivation of host species, low adoption of soil fertility analysis and liming and conservation practices, and community use of agricultural machinery and implements without prior cleaning. The disease was associated with more acidic soils, subject to greater water accumulation and with high levels of Al3+ as well as with higher Al contents and accumulation in the roots. Management practices must be adopted in the region to reduce the potential inoculum of P. brassicae and to increase soil fertility.

Varying Effects of Organic Waste Products on Yields of Market Garden Crops in a 4-Year Field Experiment under Tropical Conditions

Controlling organic and mineral fertilisation is a major concern in tropical environments. An experiment was conducted on an arenosol in the Dakar region, the main market gardening area of Senegal, to evaluate treatments commonly used by farmers. Seven treatments were repeated three times: A mineral fertilisation (MF) treatment based on N-P2O5-K2O (10-10-20), and three organic treatments at two doses (dried sewage sludge (SS), poultry litter (PL) and a digestate from an anaerobic digestion (AD) of cow manures). Each of the organic treatments were supplemented with a normal dose (1) and a double dose (2) of mineral N and K fertiliser. A lettuce, carrot and tomato rotation was grown in four campaigns (2016–2020) on all of the plots. Yields of all three crops in all of the organic treatments were statistically similar (p > 0.05) to the MF in all four campaigns, except for the yield of the lettuce crop under treatment PL-2 in campaigns 2 and 3. The tomato yields were statistically similar under all of the organic treatments in all four campaigns. In contrast, the yields of the lettuce and carrot crops differed statistically from each other and under the different organic treatments in all four campaigns. The yields of all three crops differed in the campaigns with the fertilisation treatment. In each campaign, the yields of each crop were not correlated with the total amounts of N, P and K applied. These differences or similarities in yields are explained by the nature of the organic waste products, the accumulation of nutrients after several applications, the type of crop and interannual differences in temperature.

Combining Ability and Gene Action for Yield Improvement in Kenaf (Hibiscus Cannabinus L.) Under Tropical Conditions Through Diallel Mating Design

Nine morphologically distinct kenaf genotypes were hybridized to produce 36 hybrids following a half diallel mating design. The combining ability and gene action of 15 yield and yield components were assessed in hybrids and their parents across two environments. Except for the mid diameter and plant height traits, there were highly significant differences (p ≤ 0.01) between both the analysis of variance of environments and the interaction of genotype and environment. For the inheritance of these traits, additive gene effects were considerable, and the expression of these additive genes was heavily influenced by the environment. Significant differences were found for all studied traits for GCA except top diameter, and SCA except plant height and top diameter, implying the presence of both additive and non-additive gene action for the inheritance of the concerned characters. For all features except top diameter and number of nodes, the magnitude of GCA variation was significantly higher than that of SCA variance, indicating the additive gene's predominance. The parental lines P1, P3 and P4 were determined to be outstanding general combiners for fibre yield and yield-related parameters. Considering combining ability and genetic analysis study together, the crosses P1 × P4, P1 × P9, P2 × P3, P2 × P5, P4 × P6, P4 × P7, P4 × P9, P5 × P8, and P7 × P9 were found promising for their heterotic response to higher fibre yield, stick yield, seed yield and and could be useful by adopting proper strategies for future improvement in kenaf breeding programmes.