Identification of drought tolerant entries based on stress tolerant indices and physiological traits in RIL population of cotton (Gossypium hirsutum)

The present investigation was taken up in a recombinant inbred population of cotton at advanced stage (F₁₀) derived from the cross MCU 5 x TCH 1218 in order to identify drought tolerance lines based on stress tolerant indices and physiological traits. To achieve these objectives, 220 recombinant inbred lines, parents and check KC3 were evaluated across two locations viz., Coimbatore and Aruppukottai in a randomized block design with two replications during Kharif 2018 and stress tolerant indices were estimated from single plant yield under both locations while physiological traits were recorded at rainfed condition alone.

Based on different multivariant analyses, 18 RILs viz., RIL 16, 20, 60, 71, 73, 74, 116, 131, 134, 137, 139, 143, 146, 147, 148, 149, 164 and 168 were identified as best performers under rainfed condition for yield traits which also exhibited lowest mean rank for physiological traits. Among these entries, RIL 74 and RIL 73 had low percentage of injury and high relative water content respectively. Association analysis revealed that tolerance index, yield reduction ratio, stress tolerance index and stress susceptibility index were significant and positively correlated among themselves. Negative correlation was noticed for yield under stress (YS) with tolerance index (TOL), yield reduction ratio (Yr) and stress susceptibility index (SSI). So, these indices are used to identify the susceptible genotypes, while remaining indices exhibit significant and positive association with yield under stress and normal condition. This implies remaining traits are used to discriminate tolerant genotypes.