SHORT COMMUNICATION Physiological traits for high temperature stress tolerance in Brassica juncea Sudhir Kumar • R. K. Sairam • K. V. Prabhu Received: 10 December 2011 / Accepted: 10 December 2012 / Published online: 19 April 2013 Ó Indian Society for Plant Physiology 2013 Temperature stress is one of the major limitations to crop productivity worldwide. Identifying suitable screening indices and quantifiable traits would facilitate the crop improvement process for high temperature tolerance. The objective of the present study was to screen and to identify temperature tolerant Brassica genotypes on the basis of physiological parameters viz. relative water content (RWC), total chlorophyll content, membrane stability index (MSI), total carotenoid content and yield. Fifteen Brassica juncea genotypes subjected to temperature stress by growing the crops at three dates of sowing i.e. 15th October (D 1 ), 1st November (D 2 ) and 15th November (D 3 ); showed decrease in RWC, MSI and chlorophyll content at D 2 and D 3 sowings compared to the D 1 . Genotypes like Proagro, NDR 8801 and CS-52 showed lower decline in MSI, RWC, chlorophyll and carotenoid content in leaves and seed yield/plant, while Pusa Agrani, EJ-15 and Pusa Tarak showed comparatively greater decline in the above parameters. The results suggest that physiological param- eters like MSI, RWC and chlorophyll and carotenoid contents can be used as simple indices for screening and identifying temperature stress tolerant genotypes. Keywords Brassica Á Chlorophyll Á Membrane stability index Á Relative water content Á Temperature stress Á Yield Identification of suitable genotypes and management practices to sustain the crop productivity under the climate change scenario is very essential (Aggarwal and Kalra 1994). Global earth temperatures have increased by 0.74 °C during twentieth century, and are likely to increase by 1.1–6.4 °C by 2100 (IPCC 2007). Various studies demonstrate that variability in temperature affects the grain and seed yield of annual crops (Semenov and Porter 1995). Differential response of temperature change (rise) to vari- ous crops has been noticed under different production environments (Tashiro and Wardlaw 1990). Winter crops are especially vulnerable to high temperature during reproductive phages. Brassica juncea commonly known as rai is an important winter season oilseed crop of India. Rapeseed-mustard constitutes an important source of edible oil next to soy- bean and groundnut in India. This crop inter/mixed-crop- ping with wheat is raised and is affected by high temperature stress during reproductive stage (Brandt and McGregor 1997). Plant response to heat/temperature stress also depends on its developmental stage. High temperature during reproductive phase has been reported to cause a reduction in fertility and seed yield in wheat (Saini et al. 1983), cowpea (Ahmed and Hall 1993) and pea (Guilioni et al. 1997) reduced crop yield (Hall 1992). High temper- ature in Brassica caused flower abortion with appreciable loss in seed yield (Rao et al. 1992). Temperature stress affects various physiological parameters of plant like relative water content (RWC), membrane stability index (MSI) and chlorophyll content. Yordanov et al. (2000) reported that heat stress caused S. Kumar Project Directorate for Farming Systems Research, Modipuram, Meerut 250 110, India e-mail: sudhirnpf@gmail.com R. K. Sairam (&) Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi 110 012, India e-mail: rks_ppl@yahoo.co.uk K. V. Prabhu Division of Genetics, Indian Agricultural Research Institute, New Delhi 110 012, India 123 Ind J Plant Physiol. (January–March 2013) 18(1):89–93 DOI 10.1007/s40502-013-0015-1