Effect of nitrogen application timing on growth, grain yield and eating quality of the KD18 and TH3-3 rice varieties

This study examined the effect of nitrogen application timing on growth characteristics and seed quality in inbred KD18 and hybrid TH3-3 rice varieties. A pot experiment was conducted in 2012 in a greenhouse at Kyushu University, Japan. The treatments were TO (no nitrogen application), T1 (40:40:20), T2 (50:50:0), T3 (50:30:20), and T4 (50:20:30), with the ratios indicating the percentages of total nitrogen applied at the basal, active tillering, and panicle initiation stages. Tiller number and panicle number were highest in T2. The soil plant analysis development (SPAD) value was higher in T2 until the panicle initiation stage, after which it was higher in T4 for both varieties. KD18 produced more grain weight in T4 and T2, whereas TH3-3 produced the highest grain weight in T3. Late nitrogen application timing (T3 and T4) increased the starch and amylopectin content of the hybrid rice and the protein content of the inbred rice.