Agriculture Reference
In-Depth Information
4
REPRODUCTIVE
DEVELOPMENT
Frequently occurring low temperature causes more than 50%
yield loss. Diseases such as blast and sheath brown rot adds
to the damage especially, when it attacks at the plants early
vegetative stage. In China, the recorded yield loss due to low
temperature is 3-5 million tons. In 1980, Korea lost an average
yield of 3.9 tons per hectare.
Cold tolerance is a complex trait controlled by many
genes. IRRI scientists have identifi ed three regions of the rice
genome that have a direct link to cold tolerance at the plant's
reproductive stage. Cold stress at critical times of reproduction
hinders the formation of fertile pollen that is crucial for
fertilization and consequently the rice plant may fail to produce
grains.
Panicle initiation is the start of the reproductive phase of
rice development. It is when the actual panicle or head begins
to form in the base of the shoots or stems, just above the soil
surface. The formation of the panicle marks the end of tillering
or vegetative phase and the beginning of the reproductive
phase. Panicle initiation is defi ned as when three out of ten
