【作者】 钱善勤；

【导师】 王忠； 顾蕴洁；

【作者基本信息】 扬州大学 ， 植物学， 2005， 硕士

【摘要】 为了探讨水稻根负向光性的机理,进行了化学物质（CaCl₂、EDTA）和激素（IAA、TIBA、CTK）的试验,测定光照后根尖受光侧与背光侧的IAA含量,用含有IAA的琼脂块贴在种子根的根尖表面来观测IAA对根的生长效应,并观察水稻根弯曲部位的显微结构。结果如下:（1）水稻的种子根和不定根,以及由这些根上长出的分枝根都具有负向光生长的习性。水稻根的负向光倾斜度一般在25～60°之间。通常高节位不定根的负向光倾斜度大于低节位不定根,更大于种子根。（2）水稻根的负向光倾斜生长是由于根尖向光侧细胞的生长量大于背光侧细胞生长量所致。（3）感受光刺激的部位是根冠。对根冠遮光而给根尖其他部分照光时,稻根不发生负向光性反应。剥除根冠而保留根尖的分生区和伸长区时,根能生长但失去负向光性,保留根冠的原始细胞时,当根冠重新长出时,又恢复负向光性生长。（4）根的生长量和负向光性倾斜度受到光强的影响,在0～100μmol·m^-2·S^-1的范围内,根的生长量随光强的增加而减少,根的负向光倾斜度随光强的增加而增大。（5）蓝紫光能显著的诱导水稻根的负向光性生长,绿光也能促进根的负向光性生长,而红光和橙光无效。（6）在10～40℃的处理中,以30℃水稻根的生长量和负向光性倾斜度最大。（7）稻根负向光性与地上部分的生长无关,在将地上部分切除后,地上部分仍然能够表现出负向光性反应的特性。（8）稻根在间隙照光的情况下,在光照和重力的交替作用下,呈现出锯齿状的生长状态。（9）稻根负向光性和生长量在一定程度下随着溶液的pH值的上升而上升,但当溶液的pH值超过一定程度时,稻根的负向光性弯曲和生长均会受到抑制。（10）根冠提取物的吸收光谱显示,根冠中的物质主要是吸收近紫外和蓝光区的物质。（11）在EDTA处理的试验中,螯合剂抑制稻根的负向光性和伸长生长,随着EDTA浓度的升高负向光倾斜角度减小。（12）生长素溶液对根的负向光性生长有显著的影响。在0～100mg·L^-1的浓度范围内,随着IAA的浓度提高对根的生长、负向光性和向重性反应的抑制程度加剧。当IAA≥10mg·L^-1时,水稻根负向光性完全受到抑制。（13）生长素极性运输的抑制剂TIBA也能够显著抑制稻根的负向光性反应。（14）种子根的生长方向既受光的调控也受外施的IAA的调控,黑暗中根尖向贴有含IAA琼脂块的一侧弯曲生长。更多还原

【Abstract】 To properly study the mechanism of negative phototropism of rice (Oryza sativa L.) root, chemical reagent (CaCl2、 EDTA) and plant hormone (IAA, TIB A, CTK) were used in our experiment, IAA concentration in the irradiated side and the shaded side of the root tip after irriadiation was determined, and microstructure of the bending part of rice root was observed. All the results were shown as the follows: (1) All the seminal roots, adventitious roots and their branched roots bent away from light, and their curvatures ranged from 25 to 60 °. The curvature of adventitious root of the . higher node was often larger than that of the lower node, and even larger than that of the seminal root. (2) The negative phototropic bending of the rice root was mainly due to the larger growth increment of root-tip cells of the irradiated side than that of the shaded side. (3) Root cap was the site of light perception. If root cap was shaded when the root was irradiated, the root showed no negative phototropism’ And the root lost the characteristics of negative phototropism when root cap was divested completely. Rice root could restore the characteristic of negative phototropism when the new root cap grew up, if the original cells of root cap were well protected while root cap was divested. (4) The growth increment and curvature of rice root were both influenced by light intensity. Within the range of 0~ 100 μ mol · m-2 · s-1, the increasing of light intensity resulted in the decreasing of the growth increment and the increasing of the curvature of rice root. (5)The growth increment and the curvature reached the maximum at 30℃ with the temperature treatment of 10~40℃. (6) Blue-violet light could prominently induce the negative phototropism of rice root, while red light had no such effect. (7) The negative phototropism of rice root had nothing to do with the upper part of rice, when the upper part of rice was cut, the root can show the characteristics of negative phototropism with little influence. (8) When rice root was subjected to intermitted irridation, rice root was subjected to the action of light and gravity, it showed the shape as a saw. (9) The growth and negative phototropism of rice root was promoted when the pH value under a certain degree, but when the pH value of the concentration wasabove certain degree, the growth and negative phototropism was inhibited. (10) From the absorbtion spectrum of the abstracts, it could be said that the extractives of the root caps mainly absorb at the field of ultra-violet and blue/UV. (11) In the experiment of EDTA, the chelator EDTA inhibited the growth and negative phototropism of rice root remarkably. (12) The auxin (IAA) in the solution as a very prominent influencing factor, in the range of 0~ 100 mg · L-1 , the auxin inhibited the growth, the negative phototropism and the gravitropism of rice root when the concentration of IAA increased. The response of negative phototropism of rice root disappeared when the concentration of IAA was above 10 mg· L-1 (13) The growth and negative phototropism of rice root was inhibited by auxin transported inhibitor the plant hormone CTK and TIBA, the inhibition degree was enhanced with the enhancement of the hormone of CTK or TIBA. (14) The results showed that the growth of seminal roots could be regulated by exogenous IAA as well as light, and the root bent toward the side applied with IAA in darkness.更多还原