Full Length Research Paper

Accumulation and distribution of dry matter in relation to root yield of cassava under a fluctuating water table in inland valley ecology

Mohamed T. Lahai¹* and Indira J. Ekanayake²

¹Department of Crop Science, Njala University, Freetown, Sierra Leone.

²International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, c/o L.W. Lambourn and Co., Carolyn House, 6 Dingwall Road, Croydon CR93EE, England.

*Corresponding author. E-mail: drmtlahai@yahoo.com. Tel.: +23233838551.

Accepted 10 April, 2009

   Abstract

Cassava an important staple food is grown both in upland and inland valley in the tropics. A trial to assess dry matter production and partitioning in relation to root yield was conducted in 3 positions along inland valley toposequence using 4 x 4 Latin square design. Dry matter partitioning differed among cultivars, toposequence positions, sites and years due to differences in water table depth and weather conditions. High dry matter partitioning to leaves, stems, fibrous roots and rootstocks reduced yield, while high biomass allocation to storage roots increased yield. High dry matter partitioning to leaves reduced yield more in the landrace likely due to low sink capacity. Partitioning high dry matter to leaves reduced yield more at deep than shallow water table depth. Excess moisture stress increased dry matter accumulation in rootstock, fibrous and storage roots, but decreased partitioning to stems and leaves. Drought stress reduced dry matter allocation to storage roots, but increased partitioning to rootstocks, fibrous roots and stems. TMS 91/02324 and TMS 91/02327 with lowest dry matter accumulation in stems and fibrous roots and highest in storage roots had the highest yields and therefore better adapted to inland valley conditions.

Key words: Dry matter partitioning, root yield, groundwater table depth, inland valley ecology, weather condition, cassava.