Effects of soil moisture on wheat grain yield and zinc utilization in zinc-deficient dryland soil

【Objectives】 Zinc-deficient in dryland soil caused by low organic matter, high pH and calcium carbonate contents, along with the deficiency of water supply not only constrains the winter wheat growth and yield, but also uptake and utilization of zinc(Zn). Therefore, a two-year field experiment was carried out on a typical Zn-deficient dryland soil with irrigation to the Zn-applied winter wheat in the northwest part of China to investigate the effects of soil moisture on soil Zn availability, wheat growth, yield formation, uptake and utilization of Zn and other relevant elements. 【Methods】The field experiment was conducted in Yongshou County of Shanxi Province during 2010-2012. A split plot design was used with the Zn application rates of 0 and 50 kg/hm2 as the main plot factors, the addition and no addition of supplemental irrigation as subplot factors. At mature stage, samples were collected and measured, which included grain yield, crop biomass, contents of Zn, nitrogen(N), Phosphorus(P), potassium(K)and Ferrum(Fe)in different organs or parts of crops. Zn content was also determined for 0-40 cm layers of soil. 【Results】 Results showed that irrigation of 20 to 30 mm water at jointing or booting stage had no significant effects on grain yield and soil available Zn(DTPA-Zn). However, it tended to increase grain Zn contents and Zn fertilizer use efficiency. The grain Zn contents increased by 3.8%-16.3% and 3.8%-13.1%, when supplemental was irrigation under no Zn and Zn application treatments, respectively. Zn use efficiency under supplemental irrigation was increased by 21.2%-177.8%. Supplemental irrigation amount and time also affected the Zn accumulation and distribution in different organs or parts of winter wheat. The Zn harvest index of Zn and no Zn application treatments was decreased by 5.1% and 2.0% in 2010-2011, increased by 2.1% and 2.7% in 2011-2012, respectively. Effects of supplemental irrigation on Fe and macro-element N, P and K were also different in both years.【Conclusions】 On Zn-deficient dryland soil, supplemental irrigation showed no significant effects on winter wheat grain yield and soil available Zn contents, however, it increased the Zn contents in different organs or parts and Zn fertilizer use efficiency. This indicates that integrated management of water and fertilizer with increasing the availability of soil Zn and fertilizer Zn should be given special attentions. Especially in dryland area with Zn-deficient soils it is of potential significance for the improvement of Zn nutrition levels for local crops and people.