Hugh Harries - Tropical Tree Crops Agronomist


Return to Home Page

1997 ENGLAND Trees as Crops. Tropical Agriculture Association, Oxford

1997 TANZANIA A cashew breeding programme for Tanzania. International Cashew & Coconut Conference, Dar es Salaam, Tanzania, February 1997

1993-1996 Plant Breeder, ODA Cashew Research Project

To produce improved cashew clones to be vegetatively propagated by farmers; for use as parents in the breeders' crossing garden; and as parents in polyclonal seed gardens; the new material to produce economic crops when grown under good management despite powdery mildew (Oidium anacardii) or other diseases and Helopeltis spp. or other pests; the material to fit into practical intercropping systems on the poor soils and in the unreliable climates, where cashew is customarily grown with low inputs.

A cashew breeding programme for Tanzania

At Naliendele ARI a breeding programme to generate new cashew clones started in 1996 and is expected to continue for the foreseeable future. Crosses are planned annually and made using standard seed parents in a crossing garden where 102 selected clones are available. The pollen parents are individual trees, from both Tanzanian and overseas accessions, selected from the trials planted at Naliendele. The crosses aim to combine complementary qualities from parents with contrasting characteristics, taking care to prevent inbreeding depression by avoiding parents with a common ancestry. The seed produced is germinated and grafted onto mature seedling rootstocks to appraise, in one or two years, hypersensitivity to powdery mildew, bud vigour and kernel quality. A selection-rejection ratio of 1:20 is proposed for this stage. The selected plants are multiplied by budding or grafting for growing in progeny row trials within existing planted areas at Naliendele. The plants are appraised over three consecutive crop years for growth and vegetative habit, Helopeltis tolerance, powdery mildew resistance, with and without chemical control, yield in terms of nut weight and number and quality as percent kernel out-turn. The selection-rejection ratio at this point might be 1:50 and it may be possible to use some selections as pollinators in the crossing garden. The material remaining after the second selection is top- worked for performance testing in on-station and on-farm trials. These trials are also appraised for at least three consecutive crop years under regular farm and plantation management. Some selections may continue to be used as pollinators. Additional selection criteria at this stage include evaluation by farmers and cashewnut buyers and take GxE interactions into account. The final selections replace inferior clones in the polyclonal seed gardens - to improve their seed production, in the scion gardens - to be available for vegetative propagaattioon and in the crossing garden - to become parents for the next cycle of crosses. The new clones will be named for release through the Ministry of Agriculture's Variety Release Committee. General information about them will be available to farmers in a Cashew Clone Catalogue and detailed performance data will be published. Now that the breeding programme has started, new material will become available for testing every year for as long as crossing continues. Unavoidably, the first round of crossing, appraisal and selection will take up to nine years to complete. Thereafter, new material should become available for release every year.

Harries, H.C., Kusolwa, P.M., Millanzi, K.J. & Masawe, P.A.L.M. (1997) A cashew breeding programme for Tanzania. Proc Int Cashew & Coconut Cong, Dar es Salaam, Tanzania

Other publications:

Martin, P.J., Topper, C.P., Bashiru, R.A., Boma, F., de Waal, D., Harries, H.C., Kasuga, L.J., Katanila, N., Kikoka, L.P., Lamboll, R., Maddison, A.C., Majule, A.E., Masawe, P.A., Millanzi, K.J., Nathaniels, N.Q., Shomari, S.H., Sijaona, M.E. & Stathers, T. (1996) Cashew nut production in Tanzania: constraints and progress through integrated crop management. Crop Protection 16 (1), 5-14

Harries, H.C. & Jackson, D.K. (1997) Data organization for the cashew breeding programme. Proc Int Cashew & Coconut Cong, Dar es Salaam, Tasnzania



[Parts of this Web site are still under construction Ask me if you want to know more]