Comparison of root systems among rice cultivars by simplified investigation methods.

摘要

Simplified investigation methods of root systems in Japanese and American rice cultivars were examined using photographic recording methods and image analysis on a personal computer. In order to photograph flat expanded root systems, plastic boardswere inserted vertically into the soil and culture boxes before sowing or planting in each experiment. Each root system profile picture was divided into parts every 5 cm from the plant and at an angle of 22.5?from the horizontal. The 'center of root system gravity' (CRSG) was calculated as integrated position value (PV) X root projection area (RPA)/the sum of RPA and 'moment of root system' (MRS) was calculated as integrated PV X RPA in each part. In field experiments, cultivar differences in root system profiles were easily revealed, and all American cultivars except New bonnet showed a tendency of deep distribution and large root quantity (CRSG: Lemont > New bonnet ?M-401 > M-7 ?Ishikari > Nipponbare > Tsukinohikari ?Nakateshinsenbon, MRS: M-401> M-7 > Lemont ?Nipponbare > Nakateshinsenbon ?Tsukinohikari ?New bonnet ?Ishikari). In large root box experiments, it was possible to obtain the values of CRSG and MRS similar to those obtained in the field experiments, however, it was difficult toevaluate numerous cultivars owing to the high cost of root boxes and troublesome management. In small plastic root boxes and water culture experiments, it was not possible to obtain accurate values for them.