Water requirement regularity in Linze jujube (Ziziphus jujuba Mill. var.inermis Rehd. cv. Linze jujube) and jujube/crop complex systems in Linze oasis

The water balance method was used to study water requirement regularity of Linze jujube, spring wheat, alfalfa monoculture system and Linze jujube/spring wheat, Linze jujube/alfalfa complex system in an 8 m3 observation pool (2 m × 2 m × 2 m ) under field environment. The results show that water requirements in the inner and edge oases for Linze jujube from root-activation to leaf-shedding stage are respectively 497.2 mm and 859.2 mm, spring wheat from sowing to harvesting stage are 447.9 mm and 809.9 mm and those for alfalfa from greening to frosting are 583.7 mm and 945.7 mm. Water requirements in the inner and edge oases for Linze jujube/spring wheat complex system are respectively 647.7 mm and 1 009.7 mm and those for Linze jujube/alfalfa complex system are 980.3 mm and 1 342.3 mm. In the edge oasis, the increased water require-ment of Linze jujube/spring wheat system is 17.5% and 24.7% of Linze jujube and spring wheat water requirement respec-tively. That of Linze jujube/alfalfa system is 56.2% and 41.9% of Linze jujube and alfalfa respectively. In the inner oasis, water requirement for Linze jujube is 84.6 mm in spring (April 25～May 31), 351.3 mm in summer (Jun. 1～Aug. 31) and 61.3 mm in au-tumn (Sep. 1～Oct. 5). For the growth period, water requirement is maximum (4.8 mm·d^-1) in July and 4.3 mm·d^-1 in June, with an average water requirement of 3.1 mm·d^-1. Linze jujube irrigation should be ensured in the four key periods of before flowering, fruit swelling, accelerated fruit growth and over-wintering. Irrigation amounts for these periods of growth should be 1 200 m3·hm^-2.