English

Abstract

Salinity is one of the most alarming abiotic stress affecting crop productivity and significant crop loss globally. It impedes plant performance by inducing deleterious effects on germination and plant vigor. Moreover, 6% of total land area and 30% in irrigated lands are affected by salinity (Fahad et al., 2014). This leads to massive loss in terms of productivity and arable land, as most of the economically important particularly horticultural crops are sensitive to salinity. Chilli is an important cash crop due to its high economical and nutritional value of its fruit (Howard et al., 2000). It is generally categorized as salt sensitive crop. Salt stress reduces chilli production (Navarro et al., 2002). Salinity stress cause changes in physiological processes that cause reduction in plant growth and productivity. Salt stress, increased osmotic potential, generates water deficit conditions in the soil (Navarro et al., 2003), ionic toxicity, because of high concentration of toxic ions (Na and Cl) that accumulate within the plant, ionic imbalance due to the accumulation of ions in the plant cells, which cause the deficiency of the others nutrients (Lycoskoufis et al., 2005). Under salinity stress increased level of reactive oxygen species (ROS) in cells causes K efflux from the cells. Increased ROS concentrations weakens the defense mechanism which leads to oxidative stress. ROS are very destructive to plants at higher concentrations. Under salinity stress ROS increases and can pose a threat to plant cells by causing lipids peroxidation, proteins oxidation, impairment of nucleic acids, inhibit activation of enzymes, activates programmed cell death and ultimately leading to death of the cells (Sharma et al., 2012). There are different approaches used to combat salt stress like conventional breeding, genetic manipulation and foliar application of osmoprotectants. The complexity and polygenic nature of salt tolerance in crops are important factors contributing to the difficulties in breeding salt tolerant crop varieties. Breeding efforts have been hampered by a lack of understanding to salt tolerance mechanisms as well as a lack of field and laboratory screening tests (Zhu, 2000). Genetic screening technique includes diverse plant genetic resources that provides opportunity to develop improved and resistant cultivars with desirable features, that are beneficial for farmers (yield potential and large seed) as well as for breeders (abiotic stress tolerance potential, disease and pest resistance and photosynthesis) (Govindaraj et al., 2015). Proline which is usually considered as an osmoprotection agent is also known to be involved in reducing the oxidative damage by scavenging the free radicals. Proline may also play a role as protein compatible hydrotrope (Ashraf and Foolad, 2007). It supports cytoplasmic acidosis and maintain Pak. J. Agri. Sci., Vol. 53(1), 43-49; 2016 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI: 10.21162/PAKJAS/16.4623 http://www.pakjas.com.pk