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Breeding maize with high contents of zinc, iron and provitamin A (PVA) could be effective in mitigating micronutrient deficiency in developing countries with a high reliance on maize-based diets. Information on the mode of inheritance of zinc, iron, PVA and grain yield (GY) would facilitate the development of varieties with enhanced contents of these nutrients. Twenty-four yellow to orange maize inbred lines and their 96 F1 hybrids generated using North Carolina Design II, were evaluated alongside four checks for two years at two locations in Nigeria. The effects of environment, hybrid and inbred line were significant for GY and contents of zinc, iron and PVA. The GY, and contents of zinc, iron and PVA of the hybrids ranged from 1.49 to 6.05 t ha−1, 22.51 to 33.33 mg kg−1, 20.04 to 29.65 mg kg−1 and 3.55 to 15.28 µg g−1, respectively. Additive gene effects controlled the accumulation of PVA and Fe, whereas both additive and non-additive gene effects controlled the inheritance of Zn and GY. Inbred lines with high general combining ability for GY and single or multiple micronutrients were identified, and could be used to develop hybrids and synthetics that combine high GY with high micronutrient content. Six hybrids combined high GY with high contents of all three micronutrients, and are recommended for further evaluation and possible release. Our study revealed the feasibility of enriching maize with multiple micronutrients without compromising grain yield.

Low yields of soybean in Nigeria are attributed to many factors such as declining soil fertility and use of low yielding soybean varieties. Phosphorus is a soybean plant growth-limiting nutrient.Therefore, application of phosphorus fertilizer at optimum level is essential. Two experiments were carried out at Ibadan, Nigeria to estimate the optimum P-fertilizer rate for soybean and to investigate the response of soybean to different sources of P fertilizer applied at the optimum rate. The treatments in the first experiment were two soybean varieties (TGX1987-10F and TGX1987-62F) and single superphosphate (SSP) fertilizer applied at five rates: 0kgPha -1 , 20kgPha -1 , 40kgPha -1 , 60kgPha -1 and 80kgPha -1 . The treatments in the second experiment were: SSP, Tithonia compost (TC), poultry manure (PM), TC+PM, SSP+TC, SSP+PM applied at optimum P (40kgPha -1 )rate obtained from Experiment 1and control. Data collected on morphological parameters, grain yield (GY) and nutrient uptake were subjected to analysis of variance, the means were separated using least significant difference (p<0.05). Results showed that TGX1987-62F (1.96Mgha -1 ) produced significantly higher GY than TGX1987-10F (1.26Mgha -1 ). Application of SSP at 40kgPha -1 produced tallest plants (131.8cm), highest number of leaves/plant (19.0), number of pods/plant (19.4), and GY (2.28Mg/ha) across the two varieties. Highest K-uptake (6.1mgplant -1 ) and Puptake (2.6mgplant -1 ) were obtained in plants treated with TC+SSP and SSP, respectively. The combination of TC and SSP at 40kgPha -1 produced highest number of flowers/plant (35.6), pods/plant (38.7) and GY (3.9Mgha -1 ). A combination of Tithonia compost and SSP applied at 40kgPha -1 will increase grain yield of soybean in South-West Nigeria.

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