GENETICS OF PHYSIOLOGICAL AND AGRONOMIC TRAITS IN UPLAND COTTON UNDER DROUGHT STRESS

Abstract

A plant is said to be under drought stress when soil water supply is not adequate to meet the transpirational demands (Krieg, 2000). Drought stress, among all types of abiotic stresses, is the most serious threat to the production of field crops (Sinclair, 1985; Almeselmani et al., 2011). Cotton is relatively more sensitive against drought (Ray et al., 1974). Drought stress affects cellular growth (Turner et al., 1986) hence retards leaf and stem elongation (Jordan, 1970), plant height (Ahmad et al., 2013; Yagmur et al., 2014) number of floral buds (Ahmad et al., 2013; Zare et al., 2014) boll development (Radin et al., 1992; Plaut et al., 1992) and eventually reduces yield of cotton (Yagmur et al., 2014; Zare et al., 2014). Boll development starts after pollination and is considered as the most sensitive stage to drought stress (Constable and Hearn, 1981). Cotton yield is directly affected by number of bolls per plant (Stockton et al., 1961; Grimes et al., 1969; Gerik et al., 1996). Fibre quality is also affected by drought stress. The turgor pressure in the fibre cell is badly affected under drought stress conditions (Dhindsa et al., 1975), which affects fibre quality traits (Yagmur et al., 2014). Breeding cultivars for drought tolerance requires genetic knowledge of physiological and agronomic traits under drought stress condition. The traits like relative water content (Tahara et al., 1990; Kumar and Singh, 1998), excised leaf water loss (Basal and Unay, 2006) and cell membrane stability (Kakani et al., 2005; Azhar et al., 2009) are considered as key parameters in screening crops for drought tolerance. Generation means analysis is commonly used to study genetic basis of variation by analyzing segregating populations. The analysis detects additive, dominance as well as additive × additive, additive × dominance and dominance × dominance interactions. Correlation analysis using an F2 population indicated linkage relationship of traits (Chen and Lubberstedt, 2010). The objective of present study was to generate genetic information about physiological and agronomic traits in upland cotton under drought stress.