Use of potassium to increase irrigated rice production

Abstract

Rice ('Oryza sativa' L) is the main staple food in Iraq, but productivity is low compared to other major rice-producing countries. The most popular rice cultivar (Amber33) has a lodging problem. Lodging of rice in Iraq reduces production by 25 - 30% and may be related to the agronomic practice since the 1960s of supplying high nitrogen (N) and phosphorus (P) nutrition in the absence of applied potassium (K). There are concerns that soil K depletion is leading to K deficiency. In addition, the inherently high salinity in many Iraqi rice-growing regions, is a further problem which can affect both yields and quality. This study investigated the effect of K application on rice growth and yield parameters and lodging incidence under high N status and flooded conditions in a Black Vertosol and clay loam soil during the years 2009 - 2011. Experiments were undertaken in glasshouses at the University of New England, and at farms in Iraq which have experienced problems with rice lodging, to investigate the effect of K fertilisation on rice growth using six rice cultivars. These cultivars (namely IR52713, IR45427, Amber13, Amber33, Koshihikari and Basmati370) are known to have different susceptibilities to lodging. The selected cultivars, Amber13 and Amber33 (standard and long culm) were most susceptible to lodging.