Changing priorities in rice grain and nutritional quality research

Abstract

Having achieved self-sufficiency in production, the rice (Oryza sativa) improvement programs now focus on sustaining the gains and enhancing the grain and nutritional quality of rice. Rice farming is labour intensive and is generally not considered remunerative. This calls for the efforts to breed rice varieties not only with higher productivity but also with superior grain quality fit for mass consumption as well as for industrial production of breakfast cereals and other rice based products. A sound understanding of the factors that contribute to the overall grain quality of rice will lay the foundation for developing new breeding and selection strategies for combining quality with high yield. With availability of some molecular markers and the information on genes controlling rice quality traits, breeding strategies now focus on improving rice grain quality by exploiting such genes. Traditionally, characteristics like right shape (medium and long slender rice grains), translucent endosperm, good milling quality, high head rice recovery, excellent cooking /eating quality, good elongation and pleasant aroma were considered important for a variety to qualify as quality rice. Besides these, thin husk, high nutrient density, least nutrient losses during milling /washing and lesser cooking time are also considered desirable traits. Of late, high nutrient density (with emphasis on increased iron, zinc, protein, provitaminA carotenoids in grain), low phytate, low glycemic index, high antioxidant value and therapeutic value and suitability to develop consumer products are also being pursued as quality/speciality traits for rice. The older and the newer traits defining quality and the present day methods that are used to assess quality are briefly discussed.