Abstract
A study was conducted to determine the mode of inheritance for grain shape and aroma traits of lines in the Uganda rice germplasm. Five aromatic and four non-aromatic rice lines were crossed in screen house using North Carolina Design II at the National Crops Resources Research Institute, Uganda. The resulting F2 seeds and their parents were planted in the field using complete randomized block design in two replications. The grain shape and aroma intensity of the harvested F3 seeds on per hill basis were determined in laboratory using instrumental and sensory evaluation procedures, respectively. The results revealed that the inheritance of grain shape and aroma traits were influenced by both additive and non-additive gene actions, but with the grain shape being dominated by additive gene action and the aroma by non-additive gene action. In addition, Supa 3, Supa 5 and Supa 1052 rice lines exhibited good general combining ability effects for the shape trait while Supa 3 and MET 13 were good general combiners for the aroma trait. The superior cross combination from Supa 3 x Supa 5 for grain shape and Supa 3 x MET 13 for aroma trait could be used for selection of the relevant traits at advanced stages of the breeding cycles. Key words: General combining ability effects, gene action, North Carolina design II, selection, sensory evaluation.
Highlights
Rice (Oryza sativa L.) is an important food crop that has grown to be a significant cash crop in Uganda (Kijima and Otsuka, 2017) and in particular, the more preferred aromatic rice (Mogga et al, 2018) reported to offer supplementary health benefits (Prodhan et al, 2017)
Parental materials used in the study comprised of nine rice lines with diverse backgrounds of Oryza sativa, Oryza barthi and Oryza glaberrima selected from the rice germplasm collection centre of National Crops Resources Research Institute (NaCRRI) with five highly-aromatic and four non-aromatic lines belonging to five sets of Multi-Environment Trial (MET) from Africa Rice Centre and Entry set from Uganda (‘E’), Namche and Komboka (Table 1)
The seeds of each rice lines comprising of E 20, E22, Namche 5 and Supa 3 as the females and Komboka, MET 3, MET 13, Supa 5 and Supa 1052 used as male parents, were planted 2017B at a rate of three hills per individual line in 10 L, capacity plastic buckets filled with loam soil and raised in NaCRRI under screen house condition
Summary
Rice (Oryza sativa L.) is an important food crop that has grown to be a significant cash crop in Uganda (Kijima and Otsuka, 2017) and in particular, the more preferred aromatic rice (Mogga et al, 2018) reported to offer supplementary health benefits (Prodhan et al, 2017). The most important rice grain traits in Uganda include grain length, shape, colour, stickiness when cooked, aroma and taste (Calingacion et al, 2015). Rice grain qualities differ around the world, long and slender shape of rice grains is preferred in Africa (Asante, 2017). Rice aroma, characterized by the sweet popcorn smell (Buttery, 1983), in both raw and cooked grains is the most important trait (Mogga et al, 2018). The grain shape gives the first impression of the grain quality influencing the choice of the rice consumers (Calingacion et al, 2015)
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