[Objective] The aim was to study the relationship between urcrose, zinc and the root system growth in rice. [Method] Changes of root system growth, ROS generation and root system proton export ability were analyzed in rice （Oryza sativa L. cv Zhonghua No.11） treated with different concentrations of Zn （NO3）3 sucrose, com- bined sucrose and Zn （NO3）3 mannitol as well as mannitol plus Zn （NO3）2. [Result] The results showed that treatment with 1-3 mM Zn（NO3）2 resulted in significant increases in total root length /number and in accumulation of H202 and 02- but decreases in root system proton export ability. With the exception of shoot length, the length of primary, adventitious, and lateral roots, and the number of adventitious, and lateral roots on primary /adventitious roots were all influenced by different concentrations of sucrose. High concentrations of sucrose caused increases in H202 and O2-, starva- tion or high concentrations of sucrose reduced root system proton export ability after treating with or without Zn. However, at the same concentration of sucrose, different changes of these indicators were observed between Zn and non-Zn treatments. The regulation of root system growth induced by sucrose was marked different from that of mannitol at the same concentration of 5%, suggesting that these effects were caused by sugar signal but not by osmotic potential. [Conclusion] This study indicat- ed that both sucrose and Zn play important roles in the regulation of rice root system growth.
[Objective] This study was aimed at exploring the effect of glucose signal on the zinc-induced growth of root system using rice as the material.[Method] The variation of root system growth,active oxygen production and proton secretion of root systems treated with various concentrations of glucose,glucose ＋ Zn（NO3）2,mannitol and Zn（NO3）2 ＋ mannitol were analyzed in rice（Oryza sativa L.cv Zhonghua no.11）.[Result] The results showed that the concentrations of glucose had affected the shoot height,primary root length,amount and length of lateral roots on primary roots,adventitious root length and length of lateral roots on adventitious roots in varying degrees,but not the amount of adventitious roots and lateral roots on adventitious roots under Zn＋ and Zn-condition.Glucose of high concentrations induced the production of active oxygen,while lacking of glucose would lead to the decrease of proton secretion of root systems.However,there were significant differences in these indexes between under Zn＋ and under Zn-condition treated with the same concentrations of glucose.The effects of glucose and mannitol with the same concentration on the growth of root systems were significantly different,indicating that the variation was resulting from sugar signal but not the osmotic potential.[Conclusion] The glucose had played important roles in the growth of rice root system both under normal condition and under Zn＋ condition.
[Objective] This study aimed to investigate the effect of superoxide radical on root system growth and auxin distribution in rice （Oryza sativa L. cv Zhonghua No.11）. [Method] With rice Zhonghua No.ll as the experimental material, the effects of DDC （SOD inhibitor） and Tiron （superoxide radical scavenger） on the root system growth, superoxide radical generation and root system auxin distribution in rice were analyzed. [Result] The growth and elongation of primary and adventitious roots were significantly promoted by DDC, while Tiron significantly inhibited the growth and elongation of shoots, primary roots and their lateral roots, and also suppressed the formation and growth of the adventitious roots as well as the elongation of their lateral roots. The superoxide radical was increased with the induction of DDC, while Tiron decreased the accumulation of superoxide radical. Increased accumulation of auxin in the vascular bundle and behind the elongation zone was observed in DDC- treated roots, while the treatment with Tiron resulted in a decrease of auxin in the same position. [Conclusion] This study indicated that the regulation of rice root sys- tem growth by superoxide radical was closely related with the accumulation and distribution of auxin.
