Characterization of tomato accessions for breeding research in Kenya

Understanding the phenotypic traits of germplasm through cultivation and assessing the morphological and agronomic characters facilitates selection of suitable parents for a breeding programme. Although tomato is the leading vegetable crop in Kenya, little work has been done to develop improved tomato varieties with farmer preferred and market demanded traits. The objective of this study was to characterize new sources of resistance to tomato bacterial wilt and other traits, farmer selections and commercial varieties to identify potential parental lines for university of Nairobi breeding program. Study genotypes were evaluated for various morphological and agronomic traits including reaction to bacterial wilt. The experiments were conducted at Kabete Field Station, University of Nairobi, Mwea Research Station of the Kenya Agricultural and Livestock Research Organization (KALRO), and in a bacterial wilt infested sick plot in a farmer’s field at Kanyei location, Kirinyaga County in 2017 and 2018. Study materials were 10 genotypes including accessions with genes for resistance to bacterial wilt, farmers’ selections and commercial varieties. Trials were laid out in a randomized complete block design with three replicates. Data were recorded on days to flowering, days to maturity, fruits per truss, fruits diameter, fruit length, fruits per plant, number of locules per fruit, average weight of fruit and resistance to bacterial wilt. Bacterial wilt incidence and severity were scored on a 0 to 5 scale (0 = no disease symptoms, 5 = entire plant dead) for two seasons. There were significant differences (P<0.05) for days to flowering, days to maturity, fruit diameter, fruit length, average fruit weight, number of fruits per plant, number of trusses per plant and the yield per hectare. High resistance to Ralstonia solanacearum was recorded on parent lines AVTO1424, AVTO1429, and AVTO1314. Moderate resistance to bacterial wilt was recorded on parent lines Danny select and Valoria select, and UC82 recorded moderate susceptibility, Cal J VF and Riogrande were susceptible while tomato Roma VF (location severity index of 4.75 on sick plot) was highly susceptible. The recorded growth parameters were : mean days to flowering: 34.50 - 40.83 days, days to maturity: 77 - 91.17 days, fruit diameter: 71.16 - 41.17 cm, fruit length: 59.83 - 46.54 cm, average fruit weight: 115-35.20 gm, number of fruits per truss: 2.83 - 4.74, number of trusses per plant: 20.10 - 30.0, yield per hectare: 59260 - 9547 kg per hectare, growth type: determinate and indeterminate, number of locules: 11.10 - 2.17 and plant stem colour: green and purple. There was high genetic variation among the test genotypes for the traits measured. This provides variability that can be exploited in a tomato breeding programme.
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Region Focus: 
East Africa
RUFORUM Working document series
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Open Access
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Web resource