Agriculture Reference
In-Depth Information
Nevertheless, brief exposure of seedlings to short duration
of chilling temperature may reduce leaf number and plant
height and once the stress is over, the plants quickly recover
and resume normal growth (Majora et al. 1982).
In normal environmental condition, it may be revealed
that rice plants grown under proper fertilization, gradually
increase the uptake of nutrients and are correlated positively
with the dry matter production. Nutrients thus observed are
translocated to the developing plant parts to maximize the
growth during vegetative stage. Thus, nutrients taken up
actively by root system are distributed to the parts of the plant,
i.e., partitioning differentiated amongst the different plant
organs. As the vegetative growth is almost linear, the uptake
of nutrients are usually gradually increasing, however, the
concentration of different nutrients may vary during the growth
depending on variety, stage of growth, abiotic conditions as
well as availability of nutrients.
Cold temperature of irrigation water reduced rice shoot
and root dry weight and plant height signifi cantly. Under
low temperature stress nitrogen was a major rice growth
determinant. Increased shoot concentrations of both phosphorus
and zinc allevated the low temperature stress. The uptake of
nitrogen, phosphorus, potassium and zinc reduced signifi cantly
at low temperature (16.5°C) with the strongest effect being
noticed for nitrogen, followed by phosphorus, potassium and
zinc. Application of nitrogen, phosphorus, potassium and zinc
increased their uptake in rice shoots. Nitrogen and potassium
had synergistic effect on their uptake. Responses to phosphorus
and zinc application were well marked at low temperature than
nitrogen and potassium application (Zia et al. 1994).
Soil temperature below 68°F affect nutrient uptake
adversely and therefore, retard growth, yield and maturity. Soil
