Yield and physiological responses of cotton to partial root-zone irrigation in the oasis field of northwest China

Field experiment was carried out to investigate the effects of alternate partial root-zone irrigation on the yield and physiological responses of cotton (Gossypium hirsutum) and the soil moisture variations in an oasis of northwest China in 2004-2005. Plants with mulching and in furrows were applied with three partial root-zone irrigation methods, i.e. conventional furrow irrigation (CFI, all furrows watered), fixed partial root-zone furrow irrigation (FFI, fixed one of every two furrows watered) and alternate partial root-zone furrow irrigation (AFI, neighboring two furrows alternatively watered), and under three irrigation levels, i.e. 22.5, 30 and 45 mm for each method. Monitoring of soil water contents in the AFI treatment proved that it was alternately changed in different root-zones in response to the irrigation method, although there existed some lateral infiltration from wetting side to drying side after each watering. Stomatal conductance and leaf transpiration of both AFI and FFI were lower than that of the conventional furrow irrigation if compared under the same irrigation amount but leaf water potentials of the three treatments showed no significant difference. In both years, AFI always achieved the highest seed cotton yield under the three irrigation levels. Higher yield and reduced water loss resulted in a higher water use efficiency (WUE) for the AFI treatment in both years. Our results suggest that AFI should be a useful water-saving irrigation method in arid region where cotton production is heavily dependent on irrigation and water resources are scarce.