Tropical agricultural research 

About: Tropical agricultural research is an academic journal published by Postgraduate Institute of Agriculture. The journal publishes majorly in the area(s): Population & Germination. It has an ISSN identifier of 1016-1422. It is also open access. Over the lifetime, 1549 publications have been published receiving 14431 citations.

Precisão e controle de qualidade em experimentos de avaliação de cultivares

Abstract: This study had as objective to propose a new approach for quality evaluation of variety trials for determination of cropping and use values (VCU), which considers three attributes simultaneously: magnitude of the residual variation, replication number, and genetic control of the trait under selection. It was also emphasized the need for using shrinkage estimators/predictors of genotypic values instead of unshrunk phenotypic means of varieties, i.e., the procedures should consider the genetic coefficient of determination of the traits, as well as the eventual heterogeneity of residual variance within varieties. Targeting an accuracy of 90%, it was concluded that Snedecor F test values associated to treatment effects in the analysis of variance should be above 5.0. The magnitude of genotypic variability of the traits is also involved in the F statistics. This means that the approach of fixing minimum values for replication number and maximum values for residual variation coefficient (CVe) is not sufficient. For traits related to yield (with low genetic coefficient of determination) the normally used replication number, between two and four, does not permit to reach the targeted accuracy, even if residual variation coefficients below 10% are aimed, and the experimentation is conducted on several sites and years. For that target accuracy it is recommended the use of at least six replications. It was also shown that shrinkage estimators provide more precise and reliable inferences concerning genotypic means of the varieties, and their use is encouraged. KEY-WORDS: Accuracy; shrinkage estimator; variance heterogeneity; biased estimator; variation coefficent.

Primeiro registro de ocorrência de Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) no Brasil

Abstract: In this study is reported the first occurrence, in Brazil, of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), which was considered up till now a quarantine pest. The notification occurred in the Goias State, in soybean; Bahia State, in volunteer soybean; and Mato Grosso State, in cotton.

Nitrous oxide emissions in agricultural soils: a review

Abstract: The greenhouse gases concentration in the atmosphere have significantly increased since the beginning of the Industrial Revolution. The most important greenhouse gases are CO2, CH4 and N2O, with CH4 and N2O presenting global warming potentials 25 and 298 times higher than CO2, respectively. Most of the N2O emissions take place in soils and are related with agricultural activities. So, this review article aimed at presenting the mechanisms of N2O formation and emission in agricultural soils, as well as gathering and discussing information on how soil management practices may be used to reduce such emissions. The N2O formation in the soil occurs mainly through nitrification and denitrification processes, which are influenced by soil moisture, temperature, oxygen concentration, amount of available organic carbon and nitrogen and soil C/N ratio. Among these factors, those related to soil could be easily altered by management practices. Therefore, understanding the processes of N2O formation in soils and the factors influencing these emissions is fundamental to develop efficient strategies to reduce N2O emissions in agricultural soils.

Taxas de decomposição de resíduos de espécies de cobertura em latossolo vermelho distroférrico

Abstract: The experiment was conducted at Embrapa Arroz e Feijao, Santo Antonio de Goias, Goias State, Brazil, on a dystrophic Oxisol under no-tillage system. The following species were used: Brachiaria, Brachiaria/corn consortium, pigeon pea, millet, guineagrass, sorghum, and Stylozanthes. The phytomass was cut, left on the soil and samples were collected, placed in nylon bags (litter bags), and periodically weighted to assess mass losses and decomposition rates, until 150 days after cutting. The relative losses of the residues, referred from the initial time to 150 days of decomposition, were in decreasing order: i) grasses – sorghum (80%) > guineagrass (64%) > millet (58%) > single Brachiaria (56%) and Brachiaria consortium (48%); and ii) leguminous – Stylozanthes (72%) > pigeon pea (65%). When the relative losses were projected to 360 days, the following order was found: i) grasses – sorghum and Brachiaria consortium (86%) > guineagrass (69%) > millet (65%) > single Brachiaria (62%); and ii) leguminous – Stylozanthes (83%) > pigeon pea (79%). KEY-WORDS: Tropical grasses; tropical leguminous; no-till; cerrados.

Innovations in Climate Risk Management: Protecting and Building Rural Livelihoods in a Variable and Changing Climate

Abstract: We argue that more effective management of climate risk must be part of the response of the international agriculture community to the double crisis of persistent poverty and a changing climate. The most promising opportunities to adapt to climate change involve action on shorter time scales that also contributes to immediate development challenges. Climate risk management (CRM) combines systematic use of climate information, and technology that reduces vulnerability and policy that transfers risk. The cost of climate risk comes both through damaging extreme events and through forfeited opportunity in climatically-favorable years. Effective CRM therefore involves managing the full range of variability, balancing hazard management with efforts to capitalize on opportunity. We discuss several innovations for managing climate risk in agriculture, which have not yet been fully mainstreamed in international agricultural research-for-development. First, effective rural climate information services enable farmers to adopt technology, intensify production, and invest in more profitable livelihoods when conditions are favorable; and to protect families and farms against the long-term consequences of adverse extremes. Second, information and decision support systems synthesize historic, monitored and forecast climate information into forms that are directly relevant to institutional decisions (planning, trade, food crisis response) that impact farmer livelihoods. Third, innovations in index-based insurance and credit overcome some of the limitations of traditional insurance, and are being applied to pre-financing food crisis response, and to removing credit constraints to adopting improved technology. We present a typology of CRM interventions around the concept of dynamic poverty traps.