Improvement of Rice Breeding for Salinity Tolerance

Dejen Bekis

doi:10.7176/jees/10-5-02

Abstract

Rice is one of the most significant food crop of the world. The production of rice is the second-highest in the world. Salinity is a serious constraint to increase rice production worldwide. Review of recent efforts achieved towards rice breeding for salinity tolerance has a paramount importance beside for rice production improvement in Ethiopia. Rice is a relatively new crop to Ethiopia; however, the crop is relatively well adapted to different parts of the country. Salinity is a problem of many irrigated, arid and semi-arid areas of the world where rain fall is insufficient to leach out salts from the root zone. Typical symptoms of salt injury in rice are stunted growth, leaf rolling, white leaf tip, white blotches in the leaf blade, drying of the older leaves and poor root growth. The main mechanisms of salt tolerance are control of salt uptake, reducing damage under excessive ion uptake and osmotic adjustment. The three major breeding approaches for salinity tolerant varietal development are conventional breeding, marker assisted selection and genetic engineering. Conventional rice breeding approaches exercised for thousands of years. But, the progress is slow, due to the time consuming process, the quantitative nature of most agronomic traits make difficulties in genotypes selection. However, modern breeding is more precise and efficient and easily identify undesirable genes that can be eliminated in future generations. In rice, markers like RAPDs, AFLPs, ISSRs and SSRs have been used. Among these DNA markers, SSRs is highly preferable for gene tagging and mapping efforts. The development of salt-tolerant variety by transgenic way needs more investigation. To date, transgenic salt tolerant variety has not yet reached at farmers’ field. In Ethiopia a little beat was done to identify rice genotypes adaptable to adverse saline soil conditions. From here on, more research findings highly crucial for the development of salinity tolerant rice varieties in the country. Therefore, it is a good opportunity for rice breeders to develop salt tolerant high yielding varieties in Ethiopia. Keywords : Conventional breeding, Genetic engineering, Marker-assisted selection, Rice, Salt tolerance DOI: 10.7176/JEES/10-5-02 Publication date: May 31 st 2020

Highlights

Rice (Oryza sativa L.) belongs to the grass family Poaceae and one of the most consumed staple foods around the world, especially in Asia
It is introduced to Ethiopia in 1970s and fastly distributed within the country due to the presence of vast suitable agro ecologies for rice production in the country (Beakaletal, 2016). 35 rice varieties were developed for different rice ecosystems in Ethiopia
The rate of increase in the consumption of rice in Africa has not been matched by corresponding increases in production and the demand-supply gap.The continent currently imports about US $5 billion worth of rice every year

Summary

Introduction

Rice (Oryza sativa L.) belongs to the grass family Poaceae and one of the most consumed staple foods around the world, especially in Asia. Among these; salinity is the second most widespread soil problem in rice growing countries next to drought which considers as a serious constraint to increase rice production worldwide. The rate of increase in the consumption of rice in Africa has not been matched by corresponding increases in production and the demand-supply gap.The continent currently imports about US $5 billion worth of rice every year. Rice is among the target commodities that have received due emphasis, considered as the ‘millennium crop’ in contributing to food and nutritional security, income generation, poverty alleviation and socio-economic development of Ethiopia. FAO (1997) defined saline soil as on that has greater than EC of saturation 4ds/m and soils exceeding ESP 15% It is one of the major obstacles to increase production in rice growing areas worldwide.

Salt Concentration

Findings

Conclusions and Recommendation