Non parameteric measures of phenotypic stability for yield attributing characters in low land rice (Oryza sativa L.)

Yield in any crop is a variable character, which is influenced~by agroclimatic conditions of the place and by the genotypes of the crop concerned. The adaptation of a variety over a wide range of environment has considerable significance in crop improvement, particularly in rainfed lowland rice, which is often cultivated under diverse agroclimatic, edaphic and management conditions: Twenty lowland rice genotypes consisting of released and elite materials, grown in seven different environments were analysed for stability of grain yield and yield attributing characters by using the non parametric approach of measuring stability (1). The estimates of stability parameters S_I⁽¹⁾ and S_I⁽²⁾ and the corresponding test statistics Z_I⁽¹⁾ and Z_I⁽²⁾ for grain yield and yield attributing characters were computed. For character panicle length, number of panicles per hill and spikelets per panicle, high significance of test statistics were observed which revealed the differences for stability among twenty genotypes. When the global test was applied, it was found that there is significant differences among the genotypes with respect to stability. Multiple comparison among the S_I⁽¹⁾ values indicated that seven genotypes were unstable and rest thirteen were stable for character grain yield.