Stability Analysis of Grain Yield of Some of Rice Genotypes by Parametric and Nonparametric Uni-variate Methods

Rice is one of the major global food crops, which is the second crop in Iran after wheat. Rice grain yield is strongly influenced by environments and breeders often determine the stability of high yield genotypes across environments before recommending a stable cultivar for release. Genotypial adaptability to environmental fluctuations is important for the stabilization of crop production over regions and years. The purpose of this study is the distinguishing the superior genotypes in terms of grain yield and yield stability in nine selected rice lines from preliminary yield test.

The nine selected lines obtained from crosses beteen IRRI lines and Iranian improved and landrace vareties and resulted from preliminary yield test of 2008-2009 cropping season, along with control cultivar Shiroudi, were evaluated in a randomized complete block design with four replications in three regions including Tonekabon, Amol and Gorgan during three cropping seasons of 2009-2012. Stability analysis were performed with environmental variance (S2i), coefficient of variation (CVi), Shukla's variance (2i) and deviation variance (S2), Wrick equivalence (Wi), regression coefficient (bi), coefficient of determination (R2), Eberhart-Russell analysis of variance, yield sability index (YSi) and nonparametric methods, , , TOP and mean and standard deviation of rank.

Simple analysis of variance showed genetic differences among genotypes. Combined analysis of variance was performed after Bartlett test and not significant of it and assurance of uniformity of experimental errors. The combined analysis of variance indicated the significant effects of genotype, year, location and interactions of genotype × year, genotype × location and genotype × year × location. Comparison of means of showed that genotypes 2, 5 and 4 were in the same group with 6565.1, 6495.1 and 6450.1 kg.ha-1, respectively and produced the highest grain yield. Analysis of variance indicated significant effect of genotype on plant height, tiller number, unfilled grain number, filled grain number, panicle length and 1000 grain weight. According to parametric stability G5, G3, G10 and G2 were stable genotypes. YSi indicated G2, G3, G4, G5 and G10 had the highest grain yield stability. Also, according to the TOP nonparametric index, genotypes 4, 10, 1, 2 and 5, and based on two criteria and , genotypes 1 and 5 were the most stable genotypes. Correlation between indices showed the use of a number of them is not very necessary and some of them that have a high correlation with each other can be removed from the analysis.

Overall, genotype 5 was stable in almost all stability methods and 2, 3, 4 and 1 in some of the methods. Therefore, Ggenotype 5 [Number 16 from IR64669-153-2-3 (A8948); (4Surinam × Deilamini)] due to its higher grain yield than all genotypes except genotype 2, low plant height, higher number of tillers, filled grain and 1000-grain weight, as well as more uniform plants and better grain types, can be selected as the superior genotypes and evaluated in field trials.