Cassava is considered one of the most productive tropical crops on marginal lands although high growth rates are achieved when it is grown under optimal conditions. This study assessed the growth and root yield of three cassava cultivars (LOCAL-MZINTI, LAL and I-89/00715) in the dry environments of Limpopo Province. A field experiment was undertaken in 2009/2010 at the University of Venda’s experimental farm, Thohoyandou using a randomized complete block design. Cassava mosaic virus disease (CMVD) incidences were scored (on a scale of 0 to 9; 9 being severe infestation) regularly, root yield and yield components were determined at 6 and 12 months after planting (MAP), and canopy regrowth rate (%) was estimated between 38 and 49 weeks after planting (WAP). There was an increase in canopy regrowth (%) from 38 WAP in all the three genotypes but this increase was much lower in LAL compared with Local-Mzinti and I-89/00715 at all measurement dates. The incidence of CMVD was greater in LAL compared with Local-Mzinti and I-89/00715 both at 16 and 25 WAP. Cultivar did not affect fresh shoot biomass at 6 and 12 MAP (9.7 and 58.8 t ha^-1, respectively), number of roots at 6 and 12 MAP (17 and 10.2, respectively), root length at 12 MAP (55 cm) and root yield at 6 and 12 MAP (38.4 and 52.7 t ha^-1, respectively). Therefore cassava may be well adapted to the dry environments of the Limpopo river basin that experience terminal drought and low mid-season temperatures.

 

Key words: Canopy regrowth, cassava mosaic virus disease, cultivars, shoot biomass.