Comparison of Water Stress Treatments in Winter Wheat Grown in Controlled Greenhouse.

At present and more in the future, irrigated agriculture will take place under water shortage. Insufficient water supply for irrigation will be the norm, and management will shift from emphasizing production per unit area towards maximizing the production per unit of water consumed.  A controlled experiment was conducted to examine the effects of different levels of water stress on physiological and morphological aspects of wheat. Winter wheat was planted in 104 twenty litter cylinders.  Four irrigation treatments were applied: (1) Well watered, (2) irrigation at 30%,  (3) 15%  and (4) 0% of the drained water content. For calculating soil water content, in each of the watering treatments, 14 cylinders had 5 TDR probes that measured the soil water content at the surface (0-15 vertically) and at 17, 33, 48 and 66 cm depths. The weight of the cylinders was continuously measured by load cells, which were connected to a data loggers and the amount of water uptake by and transpired from the plants was recorded. The amount of water applied to the different irrigation treatments was calculated from the load cells and TDR data.   Irrigation frequencies and amounts were determined by weighing the cylinders.  Irrigation was applied to the different treatment at a different rate but the total seasonal amount did not greatly differ.  The growth parameters of the two intermediate treatments were not different most of the growing season. Root growth and root distribution at different depths varied between the irrigation treatments. Except for the first date, total root length was almost similar in all irrigation treatments.  Root DW was affected by the different water regimes. Except for the early date, WW treatment had the highest Root DW and the WP had the lower root DW. No clear pattern was found for the 30 and 15% treatments.