Soil Sci.Plant Nutr. 45-1, 131-142 (1999)
Rodolfo S. Escabarte Jr., Ho Ando and Ken-ichi Kakuda
ABSTRACT
In the tropics, broadcast seeded flooded rice (BSFR)
was observed to show higher 15N recovery than transplanted rice (TPR) at
same fertilizer N management mainly due to its greater initial growth at
early stage as a result of lack of transplanting shock. This study was
conducted to compare the growth characteristics and 15N recovery at early
growth stage between BSFR and TPR under conventional and delayed (low and
medium temperature) planting environment. At both planting environment,
BSFR produced more number of tillers m-2 (600-700) than TPR (420-450) at
middle growth stage (89 days after seeding, DAS). However, TPR showed higher
crop dry weight accumulation in either planting timing resulting to bigger
total plant N uptake. Under conventional planting environment, TPR had
higher basal 15N recovery (ranging from 23-28%) than BSFR (13-16%) in 1996
while 24-26% for TPR and 14-23% in 1997 during maximum tiller (60-69 DAS)
to panicle formation stage (85-89 DAS). Under delayed planting, still TPR
had higher average basal 15N recovery (28%) than BSFR (23%) at same stages.
Results suggest that regardless of planting timing in Japan, TPR had greater
initial growth than BSFR resulting to higher N efficiency of soil and fertilizer
N in the early growth stages.
Key Words: broadcast seeded flooded rice, initial dry matter accumulation, 15N recovery, transplanting shock, transplanted rice