Abstract
The grain quality in rice is extremely important for breeding programs, in order to select lines that meet the standards demanded by the market. The quality attribute is composed by several characteristics, which can make difficult the work for breeder. Thus, the objective in this study was to verify the efficiency of the selection indexes in order to select upland rice lines that meet the grain quality standards. Fourteen lines of the Cultivation and Use Value test (CUV) of the upland rice breeding program of the Federal University of Lavras were evaluated. The experiments were conducted in the municipalities of Lavras-MG and Lambari-MG in the seasons of 2015/2016 and 2016/2017. The experimental was a randomized block design with three replications. The following characteristics were evaluated to compose the indexes: grain yield, minimum cooking time, water absorption index, grain chalkiness, integer grain percentage, grain length and width, apparent amylose content and gelatinization temperature. The following selection indexes were compared: Base index of Willians, Sum of “Ranks” of Mulamb and Mock, and Index Sum of Standardized Variables (Z Index) and also was held direct selection through grain yield. It was observed that the Base index obtained good gains with the selection for grain yield, but it was inefficient for the quality characteristics, results when used direct selection. The Ranks and Z index obtained superior and balanced gains for the characteristics, showing up more efficient in the selection of upland rice lines aiming at the quality of grains.
Highlights
IntroductionThe quality of grains in rice is focused on four main aspects: industrial quality, nutritional value, adequacy to commercial standards, and culinary and sensorial quality (Fitzgerald, Mccouch, & Hall, 2009)
Rice is a major food grown and consumed worldwide, being the most important crop in many developing countries, feeding about half of the world population (United States Department of Agriculture - USDA, 2017)
The quality of grains in rice is focused on four main aspects: industrial quality, nutritional value, adequacy to commercial standards, and culinary and sensorial quality (Fitzgerald, Mccouch, & Hall, 2009). These aspects are controlled by physicochemical factors that are fundamental for the knowledge of the characteristics of the rice grains after their preparation, assisting plant-breeding programs in the search for better cultivars
Summary
The quality of grains in rice is focused on four main aspects: industrial quality, nutritional value, adequacy to commercial standards, and culinary and sensorial quality (Fitzgerald, Mccouch, & Hall, 2009). These aspects are controlled by physicochemical factors that are fundamental for the knowledge of the characteristics of the rice grains after their preparation, assisting plant-breeding programs in the search for better cultivars. The most used methodologies are: (i) Tandem, which is based on the selection of one characteristic at a time This methodology is time consuming, expensive and of low efficiency; (ii) Independent Levels of Selection, which establish maximum and minimum levels. This methodology can lead to the exclusion of bad individuals in one specific characteristic, but good in others; (iii) Selection indexes, which gather the information of all the characteristics into a single value (Ramalho et al, 2012)
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