Zinc (Zn) deficiency, a widespread micronutrient disorder constraining rice production worldwide (Shorrocks 1992), is effectively controlled by field application of zinc sulfate (ZnSO4) (Takkar and Walker 1993). A more convenient and economical method of alleviating the deficiency, however, is desired. In greenhouse and field experiments, we studied the comparative effectiveness of various management practices in alleviating Zn deficiency in transplanted flooded rice grown in the alkaline soils of Punjab Province, Pakistan.
The greenhouse study used surface soils (0-15 cm) of Miranpur (Aquic Ustochrepts) and Eminabad series (Typic Haplorthids) with pH 7.8-8.0, EC 1.0-2.1 dS m-1, CaCO3 equivalent 1.1-2.6%, organic matter 1.4-1.7%, and DTPA Zn 0.5-1.0 mg kg-1. Pots containing 4.5-kg soil portions were arranged in a randomized complete block design (RCBD) with three replications (see table for treatments). Basal fertilization included 75 mg N soil-1, 16.4 mg P soil-1, and 23 mg K kg soil-1. Dry matter yield, Zn concentration, and total Zn uptake were recorded after harvest (cv. IR6) of whole shoots at 50 d after transplanting (DAT).