A Monte Carlo Sampling Approach to Testing Separate Families of Hypotheses: Monte Carlo Results

Research Methods/ Statistical Methods,

RESOLVING THE CONFLICTS BETWEEN PREVIOUS MEAT GENERIC ADVERTISING STUDIES

Past research disagrees about the effectiveness of generic meat advertising. The conflicting findings are shown to be due to the data transformation used by Ward and Lambert. The results support Brester and Schroeder's findings that the effect of generic meat advertising is small.Livestock Production/Industries, Marketing,

Evaluation de l’effet repulsif d’extraits de neem (Azadirachta indica A. Juss., 1830) sur le charançon de la patate douce (Cylas puncticollis Boheman, 1833) en condition de laboratoire a Korhogo, nord de la Cote d’Ivoire

Une stratégie de gestion intégrée des insectes nuisibles à la culture de la patate douce a été élaborée pour réduire les pertes dues à ceux-ci. Ainsi, les propriétés répulsives des extraits de feuilles et d’amandes de neem ont été évaluées sur Cylas puncticollis, un charançon de la patate douce. Pour ce faire, quatre concentrations d’extraits ont été préparées à raison de quatre répétitions par concentration. Le test a consisté à la détermination du pourcentage de charançons présents dans la zone traitée. Chacune des concentrations d’extraits a été appliquée sur la moitié d’un papier buvard placé dans une boite de Pétri de 9 cm de diamètre et sur lequel 10 charançons ont été posés. Les effets répulsifs des extraits ont été comparés à ceux d’un insecticide chimique et l’eau distillée. Le test avec 20 cL/L d’extraits de feuilles a causé 85 % de répulsion contre 45 % pour les amandes à 25 g/L. Les extraits ont significativement causé plus de répulsion que l’eau distillée et l’insecticide chimique. Les tests ont révélé un potentiel plus répulsif des extraits de feuilles comparé à celui des amandes. Les extraits de neem pourraient constituer une alternative crédible à la lutte chimique pour la protection de la patate douce contre ce charançon. English title: Evaluation of the repellent effect of neem extracts (Azadirachta indica A. Juss., 1830) on the sweet potato weevil (Cylas puncticollis Boheman, 1833) under laboratory conditions in Korhogo, northern Côte d’Ivoire Abstract An integrated pest management strategy for sweet potatoes has been developed to reduce pest losses. Thus, the repellent properties of neem leaf and kernel extracts were evaluated on Cylas puncticollis, a sweet potato weevil. For this purpose, four concentrations of extracts were prepared with four replicates per concentration. The test consisted of determining the percentage of weevils in the treated area. Each of the extract concentrations was applied to half of a blotting paper placed in 9 cm diameter Petri dishes on which 10 weevils were placed. The repellent effects of the extracts were compared to those of a chemical insecticide and distilled water. Test with 20 cL/L leaf extract caused 85% repellence compared to 45% for almonds at 25 g/L. Compared to the chemical insecticide and distilled water, the extracts caused significantly more repellence. The tests revealed a higher repellent potential of the leaf extracts compared to those of almonds. Neem extracts could be a credible alternative to chemical control for the protection of sweet potato against this weevil. Keywords: Neem extracts, Repellent effect, Sweet potato, Cylas puncticolli

Evaluation de quelques caractéristiques dendrométriques de trois clones d’Hevea brasiliensis Muell Arg. (PR 107, PB 86, GT 1)

L'Hevea brasiliensis Muell Arg. (Euphorbiaceae) est cultivé pour son latex dont on extrait le caoutchouc naturel. Cependant, l'hévéa peut être exploité comme bois d'oeuvre et d'énergie. Pour diversifier les produits tirés de cette espèce, une étude des caractéristiques dendrométriques et de quantification du volume de bois extractible par arbre a été conduite chez 3 clones (PR 107, PB 86 et GT 1), à Toupah au sud-est de la Côte d'Ivoire. Les résultats montrent qu'à l'exception de la hauteur et du volume de fût utile, les caractéristiques dendrométriques sont homogènes d'un clone à l'autre. Les arbres présentent un tronc cylindrique (Kf = 0,89 ± 0,02), se ramifient relativement haut (5,68 ± 0,51 m) et offrent ainsi une bonne partie de fût exploitable en bois d'oeuvre. Les vitesses de croissance continue en épaisseur (0,7 à 1cm an-1) conduisent à des diamètres acceptables de 40 à 45 cm, en fin de récolte de latex. Les volumes moyens extractibles par arbre sont de 0,464 ± 0,041 m3 en bois d'oeuvre, 0,519 ± 0,058 m3 en bois d'énergie et 0,983 ± 0,076 m3 en bois fort. Les clones d'hévéa présentent des caractéristiques dendrométriques comparables à celles des espèces de reboisement industriel.Hevea brasiliensis Muell Arg. (Euphorbiaceae) is grown for its latex from which is extracted natural rubber. However, rubberwood timber may be operated as lumber and wood energy. To diversify the products from this species, a study of dendrometric characteristics and quantification of extractable wood tree volume was conducted on 3 clones (PR 107, PB 86 and GT 1) at Toupah, south-east Côte d’Ivoire. Results show that, except for height and volume of useful drum, assessed characteristics were homogeneous from one clone to another. Trees show a cylindrical trunk (Kf = 0.89 ± 0.02), branch at relatively high level from the ground (5.68 ± 0.51 m), thus providing a important part of exploitable lumber drum. The rates of growth in thickness (0.7 to 1 cm yr-1) following late harvest of latex led to acceptable diameters of 40 to 45 cm. Extractable average volumes per tree were of 0,464 ± 0.041 m3 for lumber, 0,519 ± 0.058 m3 for fuelwood and 0,983 ± 0.076 m3 for strong wood. Rubber tree clones had dendrometric characteristics comparable to those of the industrial afforestation species.Keywords: Rubberwood, dendrometric charactristics, wood volume, Côte d’Ivoir

Stacking tolerance to drought and resistance to a parasitic weed in tropical hybrid maize for enhancing resilience to stress combinations

Open Access JournalMaize is a food security crop cultivated in the African savannas that are vulnerable to the occurrence of drought stress and Striga hermonthica infestation. The co-occurrence of these stresses can severely damage crop growth and productivity of maize. Until recently, maize breeding in International Institute of Tropical Agriculture (IITA) has focused on the development of either drought tolerant or S. hermonthica resistant germplasm using independent screening protocols. The present study was therefore conducted to examine the extent to which maize hybrids simultaneously expressing resistance to S. hermonthica and tolerance to drought (DTSTR) could be developed through sequential selection of parental lines using the two screening protocols. Regional trials involving 77 DTSTR and 22 commercial benchmark hybrids (STR and non-DTSTR) were then conducted under Striga-infested and non-infested conditions, managed drought stress and fully irrigated conditions as well as in multiple rainfed environments for 5 years. The observed yield reductions of 61% under managed drought stress and 23% under Striga-infestation created desirable stress levels leading to the detection of significant differences in grain yield among hybrids at individual stress and non-stress conditions. On average, the DTSTR hybrids out-yielded the STR and non-DTSTR commercial hybrids by 13–19% under managed drought stress and fully irrigated conditions and by −4 to 70% under Striga-infested and non-infested conditions. Among the DTSTR hybrids included in the regional trials, 33 were high yielders with better adaptability across environments under all stressful and non-stressful testing conditions. Twenty-four of the 33 DTSTR hybrids also yielded well across diverse rainfed environments. The genetic correlations of grain yield under managed drought stress with yield under Striga-infestation and multiple rainfed environments were 0.51 and 0.57, respectively. Also, a genetic correlation between yields under Striga-infestation with that recorded in multiple rainfed environments was 0.58. These results suggest that the sequential selection scheme offers an opportunity to accumulate desirable stress-related traits in parents contributing to superior agronomic performance in hybrids across stressful and diverse rainfed field environments that are commonly encountered in the tropical savannas of Africa