Abstract
Cassava mosaic disease (CMD) caused by Bemisia tabaci is among the major contributors to low cassava yield in Africa and therefore requires instituting control measures. Due to genetic diversity in cassava, only clones with superior agronomic traits, disease resistance and high yield are selected and released to farmers or deployed in breeding program. This study was conducted to evaluate the resistance of cassava half-sib families to CMD. Field trials were conducted at Kenya Agricultural and Livestock Research Organization (KALRO), at Kakamega and Alupe research stations in western Kenya from June 2016 to June 2017. Sixty progenies were compared to that of their five parents by planting cuttings in 4 × 2 meters plots. Data were collected on plant height, number of roots per plant, harvest index, root yield, dry matter content, cassava mosaic disease and whiteflies infestation. Twenty three genotypes had a mean score of 1.0 to CMD, implying that they are resistant. Cassava grown at Alupe was observed to have high number of susceptible genotypes compared to cassava grown at Kakamega, indicating the effect of the environment on the genotypes. Parental genotypes, Kaleso and MM96/4271 presented high number of progenies showing CMD resistance. Genotypes, P4G1 and P2G3 with mean root yield of 31.6 t ha-1 and 30.0 t ha-1 were the highest yielding in term of root yield. A number of half-sib families generated from MM96/4271, Kaleso and MM96/0686 performed well with respect to yield recorded on their respective parents. Evaluation of new cassava varieties under local disease conditions would most likely improve the productivity of cassava through selection of resistant clones.
Highlights
Cassava is considered as one of the most important food crop in the world
The half-sib progenies were taller than respective parents among parental genotypes MM97/0293, Kaleso and MM96/4271
Progenies from family MM96/0686 and MM96/9308 were found to be shorter than their parents
Summary
Cassava is considered as one of the most important food crop in the world. The annual production was about 276 million metric tons in 2013 (Sanginga & Mbabu, 2015). Cassava is an important subsistence and food security crop in Africa due to the level of its tolerance to poor soils, easy propagation through stem cuttings and low rainfall (Hillocks & Jennings, 2003). 90% of cassava produced in Africa is used for consumption which provides calories for about 500 million of people and constituting about 37% of energy requirements of the population’s food (Sanginga & Mbabu, 2015). National research stations being used only to test and disseminate developed varieties (DeVries & Toenniessen, 2001). In this breeding approach generally referred to as conventional plant breeding approach, the breeder undertakes all breeding activities unilaterally (Virk & Witcombe, 2007; Witcombe et al, 1996). The breeder identifies the breeding objectives, develops and test new varieties and evaluates them on research stations
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