Abstract

In order to study the response of nine cultivars spring canola (Brassica napus L.) to drought stress, an experiment was conducted in a factorial experimental on the basis of randomized complete block design with three replications under two irrigated conditions during 2009-2010 cropping season. Eleven drought tolerance indices including stress tolerance index (STI), stress susceptibility index (SSI), tolerance index (TOL), geometric mean production (GMP), mean production (MP), yield index (YI), yield stability index (YSI), drought resistance index (DI), modified stress tolerance (MSTI), relative drought index (RDI) and stress susceptibility percentage index (SSPI) were calculated based on grain yield under drought (Ys) and irrigated conditions (Yp).Yield in stress (Ys) and non-stress (Yp) conditions were significantly and positively correlated with STI, GMP, MP, YI, TOL, DI, RDI, YSI, SSPI, K₁STI and K₂STI and negatively correlated with SSI. Results of this study show thatthese indices of stress tolerance/resistance such as K₁STI, K₂STI, SSPI, RDI and DI can be used as the most suitable indicators for screening drought tolerant cultivars.Screening drought tolerantcultivars using ranking method discriminated cultivars Hyola 308, Heros and SW5001 as the most droughts tolerant. Cluster analysis classified the cultivars into three groups i.e., resistant, susceptible and tolerant to drought conditions. Therefore they are recommended to be used as parents for improvement of drought tolerance in other cultivars.

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