Modelling relationship between rainfall variability and millet (Pennisetum americanum L.) and sorghum (Sorghum bicolor L. Moench.) yields in the Sudan savanna ecological zone of Nigeria

This study models the relationship between rainfall variability parameters and millet (Pennisetum americanum L.) and sorghum (Sorghum bicolor L. Moench.) yields in the Sudan Savanna ecological zone of Nigeria. Daily rainfall data recorded by the nearby stations for the period between 1981 and 2010 as well as millet and sorghum yield data were used as inputs in the model. It attempts to develop model for predicting millet and sorghum yields based on rainfall variables. The analytical tools used in developing and testing the model performance include ogive of cumulative pentad rainfall, product-moment correlation coefficient (r), stepwise multiple regression analysis and coefficient of determination (R2). The study produced four yield forecast models; three for millet at Kano, Katsina and Potiskum and the last for sorghum at Potiskum. Model accounted for 61.7% of variation in millet yield due to total annual rainfall and 68.1% in sorghum yield due to total rainfall in may assume the best-fitted yield forecast models. The unaccounted variation of 38.3% in millet yield and 31.9% in sorghum indicate other factors could influence the yield variability of the two crops. It is recommended that based on holding annual and may totals rainfall constant, the two best-fitted crop yield models should be used for planning and forecasting the yield of millet and sorghum in the study area. Key words: modelling, rainfall, yields, millet, sorghu

Influence of Allium Sativum (Garlic), Zingiber officinale (Ginger) and Syzygium aromaticum (Clove) Extract against Larvae of Aedes mosquitoes (Culicidae: Diptera)

Mosquito control has become more difficult due to the unsystematic use of synthetic chemical insecticides which have inauspicious effect on the environment. Botanical phyto-chemicals with mosquitocidal potential are now recognized as potent alternative insecticides to replace synthetic insecticides in mosquito control programs due to their excellent larvacidal activities. The present study assessed the influence of A. sativum (garlic), Z. officinale (ginger) and S. aromatic (clove) extracts against Aedes mosquitoes. Larvacidal activities of three indigenous plant extracts were studied in the range 5.0 to 30.0mg/l in the laboratory bioassay against fourth instar larvae of Aedes sp. The mortality were subjected to probit analysis to determine the lethal concentration (LC50) to kill 50 percent of treated larvae of Aedes sp. Data obtained were analyzed by Comparing experimental groups and control groups with significance level established at p<0.05. All plants tasted showed effects after 24hrs of exposure at different concentration (mg/l). However the highest mortality was found in A. Sativum (garlic) and Z. officinale (ginger) against larvae of Aedes mosquitoes with LC50 = 42.50% (2.685) and LC50 = 30.01% (4.461) mg/l, while S. aromatic(clove) was found to have lowest mortality at LC50 = 24.50% (5.52) respectively. It is therefore recommended that A. sativum(Gallic), S. aromatic (Clove) has showed larvacidal effects against Aedes mosquitoes and could be served as alternative form of botanical control against mosquitoes . Keywords: A. sativum (garlic), Z. officinale (ginger) and S. aromatic (clove), Extracts, Aedes mosquitoe