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At Shika in a subhumid environment of Nigeria, a 3-year study was carried out to select newly developed groundnut varieties for use in crop-livestock production systems. The study examined 11 groundnut varieties. Emergence time, plant stands at full emergence, forage and seed yields and yield components were examined. Whole plant samples were analysed for crude protein (CP) content. Varieties ICGV 87123 gave the lowest forage yield and cultivar M517-80I, the highest, with seven varieties recording forage yields above 5 t\ha. The CP content of forage was lowest (14n8 %) for variety M576-80I and highest (21n6 %) for variety M554-76. Mean seed yield (over 3 years) varied significantly from 0n73 to 1n68 t\ha. Only two varieties had mean seed yield 1 t\ha. The relationship between seed and forage yields was positive and significant (r l 0n529, P 0n006). Varieties RMP 12, 88-80I and M517-80 were most promising for both forage and seed production.

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SummaryGroundnut rosette, a virus disease of groundnut (Arachis hypogaea) transmitted by the aphid, Aphis craccivora Koch, reduces yield in susceptible cultivars by 30–100%. Additional sources were sought in germplasm accessions involving 2301 lines from different sources and from 252 advanced breeding lines derived from crosses involving earlier identified sources of resistance to rosette. The lines were evaluated in field screening trials using an infector row technique during 1996 and 1997 growing seasons. Among the germplasm lines, 65 accessions showed high levels of resistance while 134 breeding lines were resistant. All rosette disease resistant lines were susceptible to groundnut rosette assistor virus. This work identified germplasm and breeding lines that will contribute to an integrated management of groundnut rosette disease. These new sources also provide an opportunity to eliminate yield losses due to the rosette disease.

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Rosette is the most destructive virus disease of peanut (Arachis hypogaeaL.) in Sub-Saharan Africa. Resistant cultivars have the greatest potential for minimizing the risk of losses due to the disease. The objectives of this studywere to develop and evaluate new peanut breeding lines for reaction to rosette disease and determine their yield potential. Rosette-resistant parents were crossed with early maturing susceptible spanish types. The F 2 , F4' and F5 generations were grown in a rosette disease screening nursery. A modified bulk-pedigree method was followed in which the populations were grown in bulk until F 4 , Single plant selections were made in F 4derived F5 progenies. Yield assessment began with F 7 lines from 1996 to 1998 growing seasons at three sites. High yielding rosette resistant lines with a maturity range of90 tol15 d were identified. Some of these new lines produced pod yields Significantly higher than the previouslydeveloped resistance varieties. Promising lines have been made available to researchers in West and Central Africa and should contribute to an integrated rosette disease management program.

Twenty-three advanced groundnut lines were evaluated for yield and resistance to early leaf spot (Mycosphaerella arachidis Deighton), late leaf spot (Mycosphaerella berkeleyi W.A. Jenkins) and rosette virus in on-station trials in 2001 and 2002. All the early groundnut lines were relatively resistant to rosette virus, early leaf spot and late leaf spot except ICGV-SM-93523 and ICGV-SM-93525, which were susceptible to late leaf spot. The medium maturing lines showed mostly higher levels of diseases, except MS16-791, which performed very well against all three diseases. The late groundnut lines were mostly susceptible to one or more of the diseases, except 49-85A and ICGV-SM-93532. Nine groundnut lines, combining high yield and resistance against all three diseases, were selected for on-farm trials at four locations in 2004 and 2005. In the on-farm trials all the nine selected lines were also resistant or highly resistant to rosette and both early and late leaf spot, while the local check, Makodi, was susceptible to all three diseases in both the on-station and on-farm trials. The analysis of yield data obtained at the eight environments, based on the linear statistical model y ij = μ + a i + e j + r ij , estimated the genetic variance about three times higher than the residual variance. Still better results were obtained with the multiplicative model y ij = μa i b j + e j + r ij , where the genetic variance was more than four times higher than the residual variance and a still better differentiation of cultivars was thus possible. Significant differences in cultivar stability, expressed as the variation coefficient of the a i estimates (i.e. the variation of Standardised Relative Yields) from the multiplicative model across the eight environments, were observed. The check cultivar Makodi, though quite stable, was the lowest yielding of all tested ones. The groundnut line ICGV-1S-96805 combined very high yielding capacity and outstanding disease resistance with good, though not the highest, yield stability.