Effect of Nitrogen Fertilizer Dose and Application Timing on Yield and Nitrogen Use Efficiency of Irrigated Hybrid Rice under Semi-Arid Conditions

Nitrogen fertilizer is the major input in rice production and the optimum rate and application timing management assure profitability and sustainability of the production system. This study aims to investigate hybrid rice response to different nitrogen fertilizer levels and the timing of application and quantify hybrid rice nitrogen use efficiency. Field experiments were conducted during the dry and the wet seasons 2016 at the research station of Africa Rice at Ndiaye in Senegal. Six nitrogen rates (0, 60, 90, 120, 150 and 180 kg N/ha) and three hybrid rice varieties (AR031H, AR032H, AR033H) and one inbred variety (Sahel108) and two nitrogen fertilizer application timings (three split and four split) were combined within a split-split plot design. The results showed significant effect of nitrogen rate and timing on rice grain yield that varied from 4.10 to 11.58 tons/ha and most the yield components. Rice grain yield exhibited curvilinear relationship with the applied nitrogen rates during the dry season under both nitrogen application timings and a linear relationship during the wet season under three splits. Nitrogen rate of 150 kg/ha was revealed optimum with best performance achieved by the Hybrid rice AR033H. Hybrid rice genotypes achieved greater nitrogen use efficiency compared to the inbred rice Sahel108. Hence, hybrid rice genotypes, and nitrogen rate of 150 kg/ha applied in four splits could be recommended to improve rice production and food security for achieving self-sufficiency in rice as targeted by Senegal and the neighboring countries

ESTIMATING GENDER DIFFERENCES IN AGRICULTURAL PRODUCTIVITY: BIASES DUE TO OMISSION OF GENDER-INFLUENCED VARIABLES AND ENDOGENEITY OF REGRESSORS

This study evaluates managerial differences between men and women and assesses the degree of bias introduced by omission of gender-influenced variables and ignoring the endogeneity of farmer characteristics and input levels. The results also give insight to improving research methods for isolating the gender impact on productivity.Labor and Human Capital, Productivity Analysis,

Incidence du Yam mosaic virus (YMV) et du Cucumber mosaic virus (CMV) sur des variétés de Dioscorea spp. cultivées dans les régions de Bouaké et de Toumodi en Côte d’Ivoire

L’évolution de la distribution et de l’incidence du YMV et du CMV infectant les ignames en Côte d’Ivoire et les pertes de rendement qu’ils occasionnent nécessitent un état des lieux de leur présence. Cetteétude a pour objectif de déterminer la distribution et l’incidence du YMV et du CMV infectant cette plante à tubercule dans les deux (2) zones majeures de production (Toumodi et Bouaké) en Côte d’Ivoire. A cet effet,une identification et une caractérisation de ces deux (2) virus ont été réalisés sur 18 parcelles paysannes reparties dans trois (3) localités de chacune des zones. Les tests de détection (TAS-ELISA pour le YMV; TASELISA et DAS-ELISA pour le CMV) réalisés sur 1152 échantillons dont 576 feuilles, 288 tiges et 288 tubercules ont confirmé la présence de ces virus. Ainsi, la mosaïque, le shoestring, et le gaufrage des feuillessont causés par le YMV tandis que les chloroses sont provoquées uniquement par le CMV. Ces virus sont présents dans la zone de Bouaké et de Toumodi avec respectivement des incidences moyennes de 88% et 95% pour le YMV et de 10,85% et 16,28% pour le CMV. Des infections mixtes (4,10%) de YMV et CMV ont été observées sur Bètè-bètè, Florido et Lokpa.Mots clés: YMV; CMV; Distribution, Incidence; tests ELISA; Infection mixte

Acute and Sub-chronic (28-day) Oral Toxicity Studies of Hydroalcohol Leaf Extract of Ageratum conyzoides L (Asteraceae)

Purpose: Ageratum conyzoides is an annual herbaceous plant commonly used in African traditional medicine as a purgative, antipyretic, anti-ulcer and wound dressing agent. The objective of this study was to investigate the acute and sub-chronic toxicity of A. conyzoides leaves in Wistar rats. Methods: In the acute test, the limit test dose of 5000 mg/kg was administered to Wistar rats and then observed individually 1 h post-dosing, and at least once daily for 14 days. Sub-chronic toxicity was evaluated after administering daily oral doses of 500 and 1000 mg/kg body wt., for 28 days to the rats, Biochemical and haematological assessments as well as body and relative organ weights of the rats were carried out. Results: The limit dose of 5000 mg/kg did not cause any mortality or signs of acute toxicity in the rats tested during the observation period. In the sub-chronic tests, the results did not show any treatment–related abnormalities in terms of haematological and biochemical parameters. However, urea was significantly (p < 0.05) lower in the group treated with 500 mg/kg of A. conyzoides extract. The weekly body and organ weight of the rats showed no significant differences between the control and the rats treated with the extract except for liver where there was a significant increase (p < 0.05) in rats that received 1000 mg/kg, i.e., 3 ± 0.2 g as against 2.5 ± 0.1 g for the control. Conclusion: Our results suggest that the hydroalcohol extract of A. conyzoides is relatively safe when administered orally in rats.Keywords: Ageratum conyzoides, Acute and sub-chronic toxicity, Biochemical parameters, Haematological analysis, Wistar rats

Outsourcing selective maintenance problem in failure prone multi-component systems

In many industrial settings, there are systems designed to perform consecutive missions interspersed with finite breaks during which only a set of component repairs can be carried out due to limited time, budget, or resources. The decision maker then has to decide which components to repair in order to guarantee a given performance level. This is known as the selective maintenance problem (SMP). This paper introduces a new variant of the SMP by specifically taking into account the maintenance outsourcing alternative. A novel integrated non-linear programming formulation where both the in-house and outsourcing maintenance alternatives are accounted for is developed and optimally solved. The effect of the outsourcing alternative on maintenance decisions is investigated through numerical experiments. The overall results obtained demonstrate the validity of the proposed approach. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved