Abstract

The new rice for Africa (NERICA) varieties were bred and released in West Africa. This rice has high yield, good quality and other agronomic traits that include adaptability to harsh environments found in Africa. Zimbabwe, recently introduced NERICA varieties, however, the best performing NERICA varieties under local conditions were not known and the optimum level of nitrogen fertilization for those varieties was unknown. A study was carried out to evaluate the response of introduced NERICA varieties to different levels of nitrogen fertilization in Zimbabwe during the 2011/2012 summer season. A four by four factorial experiment in a randomized complete block design was used. One factor consisted of four levels of nitrogen (0, 39.5, 64.5, and 89.5 kg / ha) and the other had four varieties (NERICA 1, NERICA 3, NERICA 7 and Mhara 1). Analysis of variance showed that there was no significant interaction between nitrogen fertilization rates and varieties. However, significant nitrogen effects (P < 0.05) were found on plant height, panicle length, filled grains per panicle, unfilled grains per panicle, grains per panicle and grain yield. Grain yield for level 1 (0 kg N / ha) was significantly reduced compared to nitrogen addition, but level 2 (39.5 kg N / ha), level 3 (64.5 kg N / ha) and level 4 (89.5 kg N / ha) were not significantly different. This showed that the optimum level of nitrogen fertilization is 39.5 kg N / ha. Varieties showed significant differences (P < 0.05) for days to 50% heading, plant height, filled grains per panicle, filled grain ratio, grains per panicle, 1000 grain weight and grain yield. All NERICA varieties performed better than the local check variety, Mhara 1 and NERICA 3 had the best yield followed by NERICA 7. Growing of these NERICA varieties using the nitrogen rate of 39.5 kg / ha can boost rice yield in Zimbabwe.

Key words: Upland rice, new rice for Africa, nitrogen fertilization, grain yield.