Analysis of Combining Ability for Early Maturity and Yield in Rice (Genus: Oryza) at the Kenyan Coast

Al-Imran Dianga,Ruth N Musila,Kamau W Joseph,Mehdi Rahimi

doi:10.1155/2020/6230784

Abstract

The main challenges facing rain-fed rice farming in Kilifi County at the Kenyan coast are inadequate and erratic rainfall, inadequate skills, and poorly developed infrastructure. Of great importance is erratic rainfall that tends to depress towards the end of long rain season, leading to crop failure. Combining ability analysis is one of the most valuable tools used to ascertain gene action effects and help in selecting desirable parents for making crosses and coming up with high yielding and early maturing lines. Combining ability for early maturity and yield has not been studied at the Kenyan coast. This study aimed at determining and identifying good, general, and specific combiners for selecting better parents and better cross combinations in rice crops for developing high yield and short duration lines in rain-fed rice farming. Seven lines were subjected to half-diallel mating design at the Kenya Agricultural and Livestock Research Organization (KALRO), Mtwapa, and at Bahari in Kilifi town. Evaluation for general combining ability (GCA) and specific combining ability (SCA) analysis was done. Combining ability variance and GCA and SCA effects were determined. Based on GCA effects, best parent for early maturity was Dourado Precoce, while for yield, Supaa, Komboka, and NERICA 10. SCA estimates indicated that best crosses for yield were D/S, D/N1, and K/N10, while the best performing cross for early maturity was D/N1.

Highlights

In Kenya, cultivation of rice is done in two ecosystems that are categorized based on water regimes basis: irrigated and rain-fed. e irrigated ecosystem produces 80% of cultivated rice, and only 20% comes from rain-fed ecosystem
Crosses were done in all possible combinations between each two of the seven parents without reciprocals to produce 21 F1 hybrids. e general combining ability (GCA) and specific combining ability (SCA) for yield and maturity among the seven lines and crosses were estimated. e F1 crosses were advanced to F2
Analysis of variance (Table 1) showed that variation among genotypes for yield, days to 50% flowering, plant height, number of tillers, unproductive tillers, unfertile spikelets, grain length, grain width, 1000 grain weight, and biomass were highly significant at P ≤ 0.001

Summary

Introduction

In Kenya, cultivation of rice is done in two ecosystems that are categorized based on water regimes basis: irrigated and rain-fed. e irrigated ecosystem produces 80% of cultivated rice, and only 20% comes from rain-fed ecosystem. In Kenya, cultivation of rice is done in two ecosystems that are categorized based on water regimes basis: irrigated and rain-fed. E irrigated ecosystem produces 80% of cultivated rice, and only 20% comes from rain-fed ecosystem. Irrigated rice is grown in Kirinyaga, Kwale, Kilifi, and Tana River counties, while rain-fed farming is mainly practised in Busia, Kakamega, and Kisumu Counties [1]. Rice consumption in Kenya has been increasing at an annual rate of 12% compared to 1% for maize and 4% for wheat. In 2017, rice consumption in the country was approximated at 700,000 metric tons seven times more than annual production range of 100,000 metric tons. Ere is potential to develop about 540,000 ha of irrigated land and 1.0 million ha in rain-fed ecology for rice production in Kenya [1]. Irrigated rice productivity in Kenya is estimated at about 4–6 t ha−1, and rain-fed productivity is about 1 t ha−1 which are below optimum production potential of about 10 t ha−1 and 7 t ha−1 for irrigated and rainfed rice, respectively [1].

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Conclusion