Based on previous complaints and reports from farmers to researchers about potato (Solanum

Open Agriculture. 2017; 2: 495-530 determined which climatic factors may be used as best predictors of the different status of pest populations (declines, outbreaks). Farmer based data was obtained using a semi structured questionnaire administered to several of farmers. Population dynamics of sweetpotato pests were monitored year-round from 2005 to 2015 in South Kivu province, eastern DRCongo. Field monitoring (visual counts) observations (population dynamic of different soil-dwelling and surface dwelling arthropods visiting sweetpotato fields) combined with a survey of farmers' knowledge on sweetpotato pests and their practices in the management of these pests in SouthKivu Province were conducted for 11 years. Monitoring (with field observations and counts) was carried out in fields under different farming practices (monocropping and inter-cropping) in sites located at different altitudes. Similarly, data for climatic factors, for the same period, were collected from Lwiro Research center. Regression models were applied to understand the linkages between environmental factors (rainfall and temperature) and pest population dynamics. The results indicated that different varieties (local and improved ones) of sweetpotato are grown three times (3 seasons) per annum under various cropping systems (sole crop, mixed crops) in various agroecological zones at different altitudes. Various arthropod species visit the crop at its different stages of development including classically known pests (Acraea acerata, Cylas spp.) or as vectors of diseases (Bemisi tabaci, Aphis spp.). The results indicated a high fluctuation in the population density of different pests. The change in the population dynamics were characterized by gradual increase in the populations during rainy seasons followed by decline during dry seasons (hot months of the year). Significant (P<0.05) https://doi.org/10.1515/opag-2017-0054 received January 2, 2016; accepted March 19, 2017 Abstract: Sweetpotato is a major food security crop grown in eastern Democratic Republic of Congo. Its production is however limited due to high prevalence of pests and diseases among other abiotic and biotic factors. A study was designed to aid understanding the knowledge of farmers about pests and their perception about climate variability impacts, as well as documenting the phenology of sweetpotato pests (pest population dynamics) in relationship with weather factors. The paper aimed at differences were observed in the population dynamics between sole sweetpotato and mixed sweetpotato intercropping. There was a synchronization of multiple pest generations (biannual, multiannual cycles of reproduction) built up with early rains. The results indicate that rainfall and maximum temperature were critical to the survival and population built up of the pest population. High rainfall in the previous months caused increases in the population density in the subsequent months within a year. The population dynamic (seasonal occurrence) over months and years was likely to coincide ...

No abstract

R. M. TSHIBINGU et al. / Int. J. Biol. Chem. Sci. 11(2): 816-827, 2017 817 Improvement of soil degraded by inorganic fertilizer, organic matter and yield evaluation of maize (Zea mays L.) in Lomami province, Democratic Republic of Congo ABSTRACTThe study was carried out in Kabinda on a degraded soil that has received inputs from organic and mineral fertilizers in order to assess their effects on maize growth and production. The experiment was conducted during two crop years, season A and season B. Five treatments in four replicates consisted of one control (T0), four levels of fertilizer (inorganic and organic matter) supply: Entada abyssinica (T1), Tithonia diversifolia (T2) Sena floribunda (T3), and Diammonophosphate DAP (T4) were evaluated using a randomized complete block system (RCBD). The observations had related to the parameters of growth and production that underwent the analysis of variance (ANOVA) at 5% level of significance. The results obtained indicate that maize responded positively in the growth stage under the effect of fertilizing indiscriminately of their nature (p <0.05) compared with the control in the two growing seasons. The fertilizers accelerated vegetative growth and increased the yield from 40 to 80% of maize compared with the control of the cropping season indiscriminately. T. diversifolia gave higher seed yield 1398.1 kg / ha and control had lower seed yield 885.5 kg / ha in season A whereas in season B, DAP produced higher seed yield 3332.8 kg / ha and the control plot gave lower seed yield 1825.kg / ha. These organic fertilizers based on E. Abyssinica, T. diversifolia, and S. floribunda were noted for their high yield scores in season A and a non-significant difference in inorganic treatment in season B. These species can be considered as significant sources of soil fertilizer to improve maize yield.

Contribution/Originality: This study is one of very few studies which have investigated yield stability and adaptability of cowpea genotype in central part of DR Congo. The paper's primary contribution is finding that stability value of AMMI (ASV) rank and diagram plot discriminated three cowpea genotypes for dissemination in central part of DR Congo.