Tea plant Camellia sp L is primarily grown
Tea plant (Camellia sp. L.) is primarily grown as a rainfed perennial plantation crop and productivity is greatly influenced by abiotic stress. It is reported that 35–40% of tea growing regions of northeast India ( Singh and Handique, 1993) and 20% in higher elevated regions of south India (The Nilgiris and High Ranges) have been affected by drought (Manival et al., 1994). The drought has caused considerable crop loss and increased casualties (Bhattacharya et al., 2014). It poses a serious threat to the industry as a whole and invites special attention to overcome this problem (Karunarathne et al., 1999). Although monsoon rains brought sufficient amounts of rainfall, irregular distribution within a year causes acute Rimonabant moisture stress mainly during the months of December and March and sometimes it extends up to mid-April. Drought affects morphological ( Mphangwe et al., 2013 and Wang et al., 2011), physiological ( Jeyaramraja et al., 2003b and Upadhyaya and Panda, 2013), biochemical ( Cheruiyot et al., 2008 and Cheruiyot et al., 2007) and molecular processes ( Bhattacharya et al., 2014, Das et al., 2012, Gupta et al., 2013 and Gupta et al., 2012) in tea plant resulting in growth inhibition, stomatal closure (Carr, 1977) with consequential reduction of transpiration (Jeyaramraja et al., 2005), decrease in chlorophyll content ( Sheshshayee et al., 2009 and Upadhyaya and Panda, 2004), decline in photosynthesis (Jeyaramraja et al., 2003b), and affects the protein synthesis (Lawlor and Cornic, 2002), to cope with osmotic changes in their tissues (Zhu, 2002). Antioxidant efficiency also varies in different clones of tea plant (Upadhyaya and Panda, 2004), and thus the response to water stress also varies (Chakraborty et al., 2002). Riccardi et al.(2004) have demonstrated that tea plant responses to water deficit shows some inherent variations, which indicate that drought tolerance has a genetic basis. Hence, drought is one of the major constraints for tea productivity. Screening the elite progenies that can withstand extreme soil moisture deficits is an important facet of the crop improvement program.