Selecting superior and high yielding recombinant inbred lines of an F11 rice population using index selection method

The most important breeding objective in most crop plants is to increase grain yield, however, the complex genetic nature of grain yield and the influence of other traits make direct selection based on grain yield less successful. Therefor, it is necessary to introduce the other traits with simpler inheritance and higher heritability than grain yield as selection criteria, so that indirect selection based on them can lead to improve grain yield in the studied population. The objective of this study was to identify and introduce appropriate selection criteria to improve grain yield in an F11 rice population using base selection index. The plant materials of this study were 141 recombinant inbred lines of F11 generation derived from a cross between two Iranian rice cultivars, Gharib and Sepidrood, which were planted in a randomized complete block design with three replications at research field of Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran, in 2018. The studied traits were included days to 50% flowering, days to maturity, plant height, number of total tiller and panicle per plant, panicle length, number of filled and unfilled grain per panicle, number of spikelet per panicle, panicle fertility percentage, 1000 grain weight, grain length, width and shape and grain yield. The results of phenotypic and genotypic path analysis showed that number of panicle per plant, number of grain per panicle and 1000-grain weight had the most positive and significant direct effects on grain yield. Assessing the base selection indices and comparing them based on different evaluated criteria, specially genetic advance of each trait and relative efficiency of index- based selection than direct selection of grain yield also showed that the use of base selection indices based on phenotypic and genotypic correlation cefficients as well as path coefficients of number of panicle per plant, number of filled grain per panicle and 1000-grain weight were the most appropriate indices for selecting high yielding lines in the studied F11 population.