Growth and development of three cotton cultivars of contrasting plant types differentially irrigated through a drip irrigation system

Water is the most important factor limiting crop production in the arid and semiarid regions of the world. A larger portion of the total cotton production in the world occurs in the semiarid regions where water is scarce, expensive and commonly of low quality. Cotton growing in these areas generally is susceptible to substancial periods of water deficits every year, affecting cotton growth and development and as a result crop productivity.;The objective of the present research was to evaluate the influence of differential irrigation treatments applied via drip irrigation on the growth and development of three contrasting cultivars. Irrigation was scheduled by tensiometers at 30 cm depth in the control plots when the soil moisture tension reached 30 kbars. The irrigation treatments consisted of 60, 80, 100 (control), 120 and 140% of the water applied to the control. Significant differences were found among irrigation treatments and cultivars in plant growth. Plant height and leaf area decreased with water stress, but square and boll dry weights increased with decreasing water supply. Among the cotton cultivars tested, McNair 220 had the lowest reproductive dry weights. Among cultivars evaluated, NX-1 had the highest vegetative, reproductive and total dry weights. Vegetative and total dry weights increased with increasing water supply in contrast to that reproductive dry weight which decreased with decreasing water supply. Fruiting-vegetative ratio (FVR) and harvest index (HI) increased under limited water supply. Among the cotton cultivars, NX-1 had the highest values of FVR and HI. Growth analysis parameters were generally positively related to water availability. Differences among cultivars for growth analysis parameters were apparent. Lint yield was unaffected by irrigation treatments, but significant differences among cultivars were observed for yield with McNair 220 having the highest yield. Significant differences in fiber properties were observed among irrigation treatments and cultivars. Lint percentage increased under water stress conditions. Water use efficiency decreased with increasing water supply and McNair 220 was the most water efficient cultivar.