Physiological traits related to drought tolerance in Brassica

Abstract

<span>Physiological basis of genetic variability in drought response and its association with yield<br /><span>and related indices is not clear in <span><em>Brassica</em><span>. In this study 36 accessions belonged to seven<br /><span>species of <span><em>Brassica </em><span>were evaluated under normal, moderate and severe stress environments.<br /><span>Physiological traits along with seed yield, seed yield components, oil content and two selection<br /><span>indices (stress tolerance index, STI and drought susceptibility index, DSI) were studied.<br /><span>Moderate and intense stress caused reduction in seed yield and the most studied traits. Based on<br /><span>the STI, <span><em>B. carinata </em><span>and <span><em>B. juncea </em><span>were identified as the superior species in moderate stress<br /><span>condition while <span><em>B. oleracea </em><span>was the most tolerant under intense stress. Moderate drought stress<br /><span>significantly increased the ratio of chlorophyll a to chlorophyll b (Chla/Chlb) while severe stress<br /><span>decreased it. Although relative water content (RWC) had positive correlation with STI, its<br /><span>heritability was low. Chlorophyll content (TChl) was associated with STI and had moderate<br /><span>heritability. Positive correlation was found between proline content and DSI under both stress<br /><span>conditions. Results showed large variation is among studied species for drought tolerance and<br /><span>related traits indicating that selection in this germplasm would be useful. Changes in<br /><span>chlorophyll content can be recognized as a key component affecting drought tolerance in<br /><span><em>Brassica</em><span>.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><br /><br class="Apple-interchange-newline" /></span></span></span></span></span></span></span></span></span></span></span></span>