Relative performance of chelated zinc and zinc sulphate for lowland rice (Oryza sativa L.)

Field experiments were conducted during the wet seasons of 2005-2006 and 2006-2007 on an Aeric Endoaquept (pH 7.2) to study the relative performance of chelated zinc [Zn ethylene diamine tetra-acetic acid (EDTA)] and zinc sulphate (ZnSO4) on the growth and yield of rice (cv. IET 4094). The diethylene triamine penta-acetic acid (DTPA) extractable (available) Zn concentration in soil and total Zn content in dry matter of rice increased initially up to 28 days of crop growth when Zn was applied as a single basal source, being greater with chelated Zn compared with ZnSO4 application. The highest mean Zn uptake by rice grain and straw was found to be 209.2 and 133.8 g ha(-1), respectively, in the treatment T-7 (1 kg Zn ha(-1) as Zn-EDTA at basal). The mean filled grain percentage, thousand grain weight and number of panicles m(-2) were highest with 90.4%, 25.4 g and 452, respectively, in treatment T-7 where 1 kg ha(-1) Zn as Zn-EDTA was applied. The highest yield of grain and straw was 5.5 and 7.3 t ha(-1), respectively, in treatment T-7, resulting in a 37.5 and 43.1% increase in yield over that of the control during both the years.