Studies on Conservative and Elastic Characters of Crop Roots

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The experiments aimed to make a distinction between conservative (characters which do not vary by environmental variation) and elastic (characters which vary by environmental variation) characters of crop root systems and to acquire the basic information on the introduction of root characters into breding a program. Six rice cultivar related to breed the Tongil were grown under excised root culture, water culture, and soil culture. The seminal root growth of seedlings were compared among cultivar. The results are as follows : 1. The growth duration required to develop fully root characters under excised root culture was three weeks (28 ^ﾟC, dark). 2. The occurrence of both L- and S- type lateral roots was observed in every cultivar under excised root culture. This result confirmed that both types of laterals were hereditary characters. 3. Similarity of root characters between Taicung Native 1 and Dee-Geo Woo-Gen was found under excised root culture. 4. Light radiation to the shoot affected the development of root characters under water culture. Variations of root characters among the plants were reduced significantly when the shoots were exposed to light. 5. When the plants re grown under submerged condition in the soil culture, the hereditary variation of seminal root character was small and difference among the cultivar was not clear. 6. Root length characters were more conservative compared to root number characters in every cultivar. The most conservative character was the density of 1st order laterals. Through experiments, it was considered that by adding the water and salinity stress to the root growth condition, phenotypic plasticity of genotype in each cultivar could be enlarged and evaluation of both conservative and elastic characters of root systems would be possible.