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In Africa, synthetic pesticide applications are overly frequent and above labelled rates. We assessed the efficacy of an insect net physical control system on field cabbage (Brassica oleracea var. capitata) production in France and Benin. Various mesh sizes and netting removal frequencies were compared under contrasting climatic conditions. Studies under Mediterranean climatic conditions (spring season) compared two mesh sizes (0.73 mm and 1.6 mm). Studies under subequatorial climatic conditions (cool and hot seasons) tested nets of mesh size 0.4 mm and 0.9 mm used either as permanent cover, removed daily, or 3 days per week. The results showed that a fine mesh did not improve the netting efficacy against pests but had a major impact on the microclimate. In Mediterranean climatic conditions, the netting efficacy and beneficial microclimate improved crop yields. In subequatorial conditions, crop yields were lowest with permanent net protection due to high temperatures under the nets and poor aphid and Spodoptera littoralis control. Removing the nets 3 days per week was a good technical/economic trade-off, ensuring acceptable efficacy with minimal effects on the microclimate. 相似文献
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The effect of Mangifera indica stem bark and Pluchea ovalis roots on tracheal smooth muscle in vitro 总被引：2，自引：0，他引：2
Agbonon A Eklu-Gadegbeku K Aklikokou K Essien K Akpagana K Gbeassor M 《Fitoterapia》2002,73(7-8):619-622
Aqueous extract of the stem bark of Mangifera indica and ethanolic extract of the roots of Pluchea ovalis has been studied on rat tracheal smooth muscle in vitro. The extract of M. indica at 1, 2 and 4 mg/ml and that of P. ovalis at 0.25, 0.5 and 1 mg/ml relaxed, dose-dependently, the rat tracheal smooth muscle strip previously contracted by acetylcholine at 0.055 mmol/l. 相似文献
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Satellite monitoring of land-use and land-cover changes in northern Togo protected areas 总被引：1，自引：0，他引：1
Fousseni Folega Chun-yu Zhang Xiu-hai Zhao Kperkouma Wala Komlan Batawila Hua-guo Huang Marra Dourma Koffi Akpagana 《林业研究》2014,25(2):385-392
Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index （NDVI） was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image （ETM＋2007） using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes： riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classi- fied map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 proba- bly due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area. 相似文献
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Rice genotype and fertilizer management for improving rice productivity under saline soil conditions
Djaman Koffi Mel Valere Boye Amith Diop Lamine Manneh Baboucarr El-Namaky Raafat Koudahe Komlan Futakuchi Koichi 《Paddy and Water Environment》2020,18(1):43-57
Paddy and Water Environment - Soil salinity is a threat to crop production in the Senegal River Delta where salt intrusion increases soil electrical conductivity and most of farmers had abandoned... 相似文献
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Kossi Koudjega Komlan Adigninou Ablede Mark Kofi Abekoe Emmanuel Owusu-Bennoah Daniel Kekeli Tsatsu 《Communications in Soil Science and Plant Analysis》2019,50(8):974-986
An experiment was conducted to determine the depth of urea supergranule (USG) application that reduces ammonia (NH3) volatilization and improves nitrogen use efficiency of rice. Canne, Voudou, Akuse, and Bumbi series were used. Treatments involved surface application of prilled urea (PU), USG applied at 0, 4, 8, 12 and 16 cm depths and a control. Rice variety IR-841 was grown up to maturity. Closed chamber device was used to trap NH3. Results indicated that the highest mean NH3 loss occurred in Bumbi series (13.67%) while the lowest was Canne series (8.16%). USG applied at 0 cm resulted in the highest NH3 loss (37.2%). NH3 volatilization decreased with increasing depth of USG application. The highest grain yields were obtained when USG was applied at 4 and 8 cm. In Canne series, the highest agronomic use efficiency (AE) of N (57 g g?1) was obtained with USG applied either at 8 or 12 cm while the highest recovery efficiency (RE) (84%) occurred at 8 cm. In Akuse series, the highest AE (55 g g?1) and RE (78%) were obtained when USG was placed at 8 cm. In Voudou and Bumbi series, the highest AE (45 and 48 g g?1 respectively) and RE (64%) were obtained with USG deep placed at 4 cm. The results therefore suggested different specific depths of USG application to reduce ammonia loss and improve nitrogen use efficiency. 相似文献
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