Studies on Conservative and Elastic Characters of Crop Roots

本试验旨在区分作物根系的保守性（不随环境变化而变化的性状）和弹性性（随环境变化而变化的性状），为将根系性状引入育种程序提供基础资料。对与水稻品种"桐吉“相关的6个水稻品种进行离体根培养、水培和土培试验。比较了不同品种种子根的生长情况。研究结果如下：1.在离体根培养条件下发育完全根性状所需的生长持续时间为三周（28 ℃，黑暗）。2.在离体根培养条件下，每个品种都出现了L型和S型侧根。这一结果证实了这两种类型都是遗传性状。3.在离体根培养条件下，发现台中乡土1号与迪吉奥优根的根系性状相似。4.水培条件下，光辐射对根系性状的发育有一定的影响。植株间根系性状的变异在地上部光照条件下显著减小。5.在土培条件下，种子根性状的遗传变异较小，品种间差异不明显。6.各品种根长性状相对于根数性状更为保守。最保守的特征是一级密度。通过试验认为，在根系生长条件中加入水分和盐分胁迫，可扩大各品种基因型的表型可塑性，使根系保守性和弹性性状的评价成为可能。

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.