Open Agriculture. 2017; 2: 600-610 bean genotypes and most of their interactions. Significant correlations were found between all germination variables and between most growth parameters. From the effect of salt application, the common bean genotypes namely KEB-CB049, KEB-CB053 and Mac-33 were the most tolerant while KEB-CB055 and KEB-CB050 were the most sensitive. The results confirm that there is genotypic variation in salinity tolerance and that the most tolerant genotypes should be further explored in selection programs, with the aim that they should be promoted for cultivation in tropical zones affected by salinity.

Soil salinity represents a major constraint limiting crop production in arid and semi-arid countries. The effect of salinity induced by sodium chloride (NaCl) at five levels (0, 50, 100, 150 and 200 mM) was investigated on four germination traits and thirteen seedling growth characteristics in twenty cowpea [Vigna unguiculata (L.) Walp.] genotypes (ET11, KEB-CP004, KEB-CP006, KEB-CP009, KEB-CP 010, KEB-CP020, KEB-CP033, KEB-CP038, KEB-CP039, KEB-CP045, KEB-CP051, KEB-CP054, KEB-CP057, KEB-CP060, KEB-CP067, KEB-CP068, KEB-CP118, MTA22, NO74 and NO1036). The germination tests were carried out on Petri dishes in the laboratory while seedling growth experiments continued in plastic pots in the greenhouse, both setting up using a randomised complete block design with three replications. Genotypic responses were significant for all germination traits (p < 0.001). Germination percentage, germination rate index, and coefficient of velocity of germination were all decreased by salt stress. However, the mean germination time increased with increasing saline conditions. Significant differences were found between genotypes for most growth attributes. Growth rate (centimeter increased in height per week) decreased significantly with increasing salinity, starting at 100 mM NaCl (24.20% reduction, 2.66 cm / week) with maximum reduction (38.58%) corresponding to 2.16 cm/week observed at 200 mM NaCl, compared to control (3.51 cm/week growth rate). Also, significant decline in shoot weights, number of functional leaves and dry matter production were observed under salinity. Salinity also reduced water content in shoot and root and did not affect root weights. Under salinity, significant correlations were found between all germination variables (p < 0.001). Growth rate was significantly associated with ten out of the twelve other seedling growth traits. Also, the dry matter production under salinity was significantly associated with all other seedling growth characteristics with the exception of root water content. Given the effect of salt stress, cowpea genotypes, namely NO1036, KEB-CP004, KEB-CP038 and KEB-CP051, were the most tolerant while KEB-CP068 and ET11 were the most sensitive ones. The results confirm substantial genetic variation in salt stress tolerance among the studied genotypes. The most tolerant genotypes should be further explored in genetic improvement programs and should be promoted for culture in regions affected by salinity.

A field experiment was conducted to investigate the effect of aqueous and ethanolic extracts of neem (Azadirachta indica A. JUSS) and garlic (Allium sativum L.) against Cercospora leaf spot (CLS) disease of groundnut (Arachis hypogaea L.). A split plot design using two exotic (“fleur” 11 var., 65-13 var.) and one local (village var.) variety of groundnut as the main factor and ten treatments comprising one negative control (sterile distilled water), one positive control (fungicide: spavozeb) and eight phyto-extracts replicated three times was applied. Treatments were applied to plots at 45, 60, 75 and 90 days after planting (DAP). Results showed that CLS disease incidence ranged between 66.67% and 88.89% at 65 DAP for 10% ethanolic extract of garlic and 20% aqueous extract of garlic, respectively. Disease severity was lowest for 20% ethanolic extracts of neem seeds (14.74%) and garlic bulb (14.99%) at 65 DAP. Yield obtained from treatments of ethanolic extracts of garlic (3.62 t ha−1) was significantly higher (p < 0.05) than the control (2.40 t ha−1) but comparable to the spavozeb treatment (3.09 t ha−1). Exotic varieties were more productive (3.13 and 3.43 t ha−1) than the more resistant local variety (2.67 t ha−1).

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Aims: To investigate the combined effect of Arbuscular Mycorrhizal Fungi (AMF) and intercropping on the control of the nematode Radopholus similis in banana. Study Design: The study involved an experiment in which banana-banana monocrops alongside banana-groundnut and banana-sweet potato intercrops were inoculated with AMF Rhizophagus irregularis MUCL 41833 to control the nematode R. similis. Place and Duration of Study: Centre Africain de Recherches sur les Bananiers et Plantains (CARBAP), from September 2016 to April 2017. Methodology: An experiment was conducted under greenhouse conditions (photoperiod 12 h. average temperature 24 - 28°C and 70 - 80% relative humidity) and R. irregularis were tested against R. similis with banana intercropped with either groundnut, sweet potato or banana itself. The plants were cultivated in boxes (30 x 15 x 10 cm) containing sterilized (2x1hour at 121°C) sand/coffee ash substrate (proportion 1:2 v/v), as an intercropping system with the following plant combinations: Banana-banana, banana-groundnut and banana-sweet potato. The experimental set-up was a completely randomized design comprising four treatments and six replicates: (1): Nematode (Nem), (2) AMF, (3) AMF + Nema and (4) control without nematode and without AMF. The ratio of banana: intercrop was 1:1 in the intercropping treatments. A total of 72 boxes was considered in the experimental set-up. Results: AMF root colonization of banana was clearly affected by intercropping with about 25% increment observed in banana co-cultivated with groundnut or sweet potato compared to banana-banana combination. Positive effects of AMF expressed as an increase in banana biomass compared to the control treatment was observed in root fresh as well as shoot dry weights. However, the impact of AMF colonization in intercropping systems on R. similis did not confirm its bioprotective effect. Intercropping had a significant (P < .05) effect on R. similis and sweet potato has been shown to be more effective in controlling R. similis with 62% reduction compared to groundnut (24% reduction). Contrarily, banana plant growth decreased in the banana / sweet potato combination. Conclusion: Findings in this study indicate that R. similis biological control in the banana intercropping system is more dependent on the intercrop species than on AMF.