Influence of nitrogen, phosphorus and potassium application on the yield of maize in the savanna zone of Nigeria

Field trials testing the effects of five rates each of N, P and K application on three hybrid and two open-pollinated maize varieties were conducted in three separate experiments on an Arenic haplustalf (USDA) at Ilora in the derived savanna and Typic paleustalf (USDA) at Mokwa in the southern guinea savanna of Nigeria. The hybrid maize varieties planted were 8516-12, 8321-18 and 8329-15 and were compared with the open-pollinated maize, TZSR-Y and TZSR-W. Nitrogen was applied at rates 0-200 kg ha-1 in the first trial, while P and K were supplied as basal nutrients. In the second trial, P was applied at rates 0- 80 kg P2O5 ha-1 using basal N and K fertilizers. In another trial, K was applied at rates 0-120 kg ha-1 with blanket application of N and P. The hybrid maize gave higher yields and used N and P more efficiently than the open pollinated at both trial locations. The yield of maize was higher in the southern guinea savanna than in the derived savanna. The performance of the hybrid varieties followed in the ascending order of 8516-12, 8321-18 and 8329-15. The optimum rates of N and P for maize grown in the derived savanna were 100 and 40 kg ha-1 respectively. In the southern guinea savanna the open pollinated and hybrid varieties responded up to 150 and 200 kg N ha-1 respectively. The 8516-12 showed higher N and P use efficiency than other varieties. Consequently, planting such variety could be advantageous, using minimal dose of fertilizer most especially, where farmers have less access to fertilizer. Key words: Hybrid maize, open pollinated maize, nitrogen use efficiency, phosphorus use efficiency. African Journal of Biotechnology Vol.2(10) 2003: 345-34

Reaction of some maize genotyhpes to infestation with the witch weed (Striga asiatica)

A total of twenty four maize genotypes comprising nine inbreds, six open pollinated, four synthetic and five hybrids were tested for tolerance to artificial infestation of Striga asiatica using seeds of the pest as inoculum source. Yields varied directly with tolerance level and reduction in plant height was observed with increase in age of the maize plants between 8 and 10 weeks after planting in most of the genotypes. Although, stem girth was not significantly different under striga infestation, plant height and leaf-area at 8 - 10 weeks were significantly different in the infested maize plants. Striga emergence counts was significant with marked effect on yield, while Striga damage rating ranged between two and four in tolerant genotypes and between five to nine among susceptible ones. Two inbreds (EV8485-Y and EV8725-100-2) STR, one hybrid (9044-27-Y) and one synthetic (NEW STR-1-W) were found to be tolerant to Striga asiatica. The tolerant maize genotypes may be desirable for introduction to S. asiatica endemic regions of Southern Guinea Savanna. Key words: Maize genotype; artificial infestation; Striga asiatica, tolerance level Moor Journal of Agricultural Research Vol.4(2) 2003: 210-21