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Jin Chul Shin
National Crop Experiment Station,
Seodundong, Kweonseon-gu, Suweon 441-100, Republic of Korea
The root system of rice plant two primary roles. One is the acquisition of nutrients and water in soil layers in soil layers, and the other is the anchorage of shoot. The function of anchorage has been ignored for the normal yield. But, now a days, much attention has been payed to it for high yielding rice cultivation. Many managements is applied for the increase shoot and panicle weight, which makes the root system worse. The results make the plants lodging. For the resist of plant to lodging, well even deep distribution of root system should be necessary. Root length density is measured to describe root system distribution.
However, the root system is hidden underneath the soil. So, the abservation
of root length density at a position in soil should depend on the distance
r from the plant base as:
Where ? is the elevation angle of the position in soil, ? is the total
number of roots per plant or hill. ? is the parameter describing rooting
shape which determines shallowness or deepness of rice root system. Large
? value, which is a characteristic of rice cultivars, gets more root in
deep angle. This model can be applied to describe rice root system with
the root length density in each soil horizons.
The ammonium ion concentration in each soil solution was very stable if roots in soil were absent. The ammonium content in the soil solution drastically decreased as root length density increase. Time course of the ammonium concentration in the soil solution was investigated.