2012 Volume 81 Issue 1 Pages 33-38
In 2008 and 2009, the characteristics of seedling emergence, dry matter production, and yield of rice direct-seeded using iron-oxide-coated seeds (Fe-seeds) were examined in comparison with those in rice direct-seeded using calcium-peroxide-coated seeds (Ca-seeds) to establish a method of direct seeding of Fe-seeds in a cold climate area. In direct seeding of Fe-seeds, early growth was reduced by a low temperature for about 4 days after seeding, compared with that in direct seeding of Ca-seeds. Thus, increase in dry weight of the top, tiller number, leaf area index, and nitrogen uptake of the seedling from Fe-seeds was delayed resulting in reduced numbers of panicles and spikelets, and yield was reduced. Even under such conditions, early growth in direct seeding of Fe-seeds was improved by seeding nearer the soil surface, and thus, the degree of the yield reduction by a low temperature was mitigated.
