冷温下水稻幼苗某些流变学特性的研究

Study of character of rheology in rice seedlings under low temperature:

水稻幼苗各位叶对冷温的反应是不同的，下位叶敏感，是应变的主要部分和冷温的受体。以水稻幼苗绿叶相对长度为指标，研究冷温和切变率（γ）之间的各种关系的结果为：（１）抗冷品种的切变率比感冷品种的小；（２）幼苗叶片在冷温下产生３种应力，即屈服应力、应变应力和松驰应力。根据Ｃａｓｓｏｎ公式计算的γ－τ图也证明存在这三部分应力及相应的三种应变方式，即无形态应变，正负应变和恒定应变；（３）在η－γ图中，粘性系数（η）有一个特定的范围，γ只有在该范围内才发生变化，抗性品种的η变化范围比感冷品种大。

The leaves of rice seedlings under low temperature are different in response to cold treatments. Lower leaves which are sensitive to low temperature are the main parts of strain and receptor of cold. According to the index of relative length of green leaves in rice seedlings in this paper, the relations of low temperature and shear rate (γ) have been studied. The results show: (1) the shear rate of cold-resistance cultivar is smaller than that of cold-susceptible one firstly. (2) Under low temperature, three kinds of stresses are induced in leaves of seedlings: yield strength, strain stress and relaxation stress, while, accor-ding to -τ figure calculated by Casson formula, there are also three types of stresses and corresponding three kinds of strains: no morphological strain, positive or negative strain and constant strain. (3) In η-γ figure, viscosity coefficient (η) has a specific range in which r can change. The changable range of η in cold-resistance cultivar is larger than that of cold-susceptible one.