锌离子活度对水稻锌积累与分配的影响

采用HEDTA螯合剂缓冲营养液培养法,选用籽粒含锌量有明显差异的2个基因型水稻(BY和Z921),设置4种锌离子活度(pZn2+9.7、10.3、11.0、11.4),研究了锌离子活度对水稻锌积累、分配的影响以及对不同时期水稻叶片中锌的化学形态的影响。结果显示:(1)2个基因型水稻各器官的锌含量都随着锌离子活度的升高而升高,但不同基因型间,同一基因型不同器官间均存在差异,供锌正常的的条件下,锌首先向代谢活性较弱的营养器官分配;缺锌的条件下,锌首先满足籽粒的需要;(2)从籽粒锌分配看,当锌离子活度(pZn2+)小于10.3时,糙米锌含量最高,当pZn2+升高到9.7时,颖壳锌含量则超过糙米,糙米和精米锌含量的比值在0.79～0.90之间,并以pZn2+为9.7时为最小;(3)任一锌离子活度下,BY籽粒锌含量均大于Z921。表明通过筛选籽粒富锌水稻品种来提高稻米锌含量是经济可行的,且通过增加环境锌离子活度来改善水稻的锌营养能显著提高水稻籽粒的锌含量;(4)营养生长前期,水稻叶片中的锌主要以活性较低的醋酸提取态(重金属磷酸盐)存在;营养生长后期,锌主要以乙醇提取态(醇溶性蛋白、氨基酸等)存在。

Partitioning and Accumulation of Zinc in Rice under Different Zn2+ Activities

Abstract：Two rice genotypes (BY and Z921), which were different in zinc content of grain, were cultivated at different Zn2+ activities(pZn2+ l14, l10, 103 and 97) in chelator buffered nutrient solution. The effects of different Zn2+ activities on the zinc partitioning in rice and the chemical forms of zinc in the rice leaves were studied, and the results were shown as follows. (1) The zinc content in each organ was increased with the increasing of Zn2+ activities, and there were differences between genotypes and the organs. Under sufficient Zn supply, Zn accumulated in vegetative organs first; then accumulated in grains. (2) Judging the zinc distribution in grain, when Zn2+ activity was lower than 103, the zinc content in brown rice was the highest, but with the Zn2+ activity reached to 97 with increasing of  the zinc content in grain hull became higher. The zinc ratio of brown rice to milled rice was in range of 079 to 090, the ratio was the smallest when pZn2+ was 97 (3) At all Zn2+ activities the grain zinc content in BY was much higher than that in Z921 which indicated that selecting zinc rich rice is a cost effective way to improve zinc in rice and zinc content in rice grain could be improved by increasing Zn2+ activity. (4) In the prophase of vegetative growth, zinc in the leaves exist in form of acetic acid extractable (heavy metal phosphates); in the later phase of vegetative growth, ethanol extractable (alcohol soluble proteins, amino acids, et al) zinc predominated in the leaves.