Tuesday, November 14, 2006 - 1:15 PM
192-2

Agrophysiological Responses of Upland NERICA Rice to Nitrogen and Phosphorus Fertilization in the Forest Agroecolology of West Africa.

Sylvester Oikeh, Francis Nwilene, Sitapha Diatta, Olu Osiname, Amadou Toure, and Segun Okhidievbie. Africa Rice Center (WARDA), Cotonou, 01 BP 2031, Benin

New Rice for Africa (NERICAs) varieties are interspecific crosses between Oryza sativa (Asian rice) and Oryza glaberrima (African rice). Even though NERICAs are being widely adopted by farmers in Africa, limited studies are available on their responses to fertilizer application. This study evaluated the influence of phosphorous and nitrogen fertilizers on some agro-physiological traits of NERICAs. In 2004 and 2005, four released NERICA varieties under two P (0 and 2.6 g m-2) and four N levels (0, 3, 6 and 12 g m-2) were evaluated at Ikenne (6º54´N, 3º42´E, 60 m asl; rainfall, 1421 mm), forest agroecology of Nigeria on an Ultisol. Nitrogen stress (zero-N) reduced time to maturity by four days compared to the highest level of N. NERICA 3 reached maximum tiller production by 2 days earlier than NERICAs 2 and 6, and matured earlier (97 DAS) than the others by 3 to 5 days. Dry matter production in 2005 was only one-half of the 2004 values because of the severe moisture stress in 2005. In spite of this severe drought, NERICA 1 gave 17% more grain yield than NERICAs 3 and 6 indicating its high potential tolerance to moisture and nitrogen stresses. In 2004, N application enhanced plant height (18%), tillers and panicles (12 – 13 %), and grain yield (50%) compared with zero-N treatment. There was no clear difference in biomass production between application of a moderate N level (6 g m2) and the highest N level. Application of moderate P (2.6 g m2) increased grain yield by 22% over zero-P. Results indicate varietal responses among NERICA rice varieties to N and P application, and moderate N and P levels were optimum for their production under the conditions of the experiment.

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