Abstract: Comparative experiments between hybrid rice genotype Weiyou 35 (tolerant to potassium deficient stress) and Shanyou 6 (sensitive to potassium deficiency) were conducted to study the effect of potassium deficient stress on respiratory metabolism. The results indicated that respiratory rate of leaves of Weiyou 35 and Shanyou 6 had different change models. The respiratory rate of Weiyou 35 kept stable before booting stage, but that of Shanyou 6 increased rapidly. With prolonging of deficient stress, the respiratory rates of both genotypes increased. Potassium deficient stress also resulted in changes of respiratory metabolism pathways. When the respiratory rate of Weiyou 35 was stable, the TCAC activity of Weiyou 35 was stronger than that of Shanyou 6. The inhibiting effect of indoacetate (1 mmol /L) counted for 69.80%-72.16% of total respiratory rate and no significant effect of potassium deficient stress existed between potassium treatments in Weiyou 35, but counted for 28.17%-42.72% and reduced by potassium deficient stress in Shanyou 6. The participation degree of respiratory electron flux through cytochrome pathway of Weiyou 35 was higher than that of Shanyou 6. Potassium deficient stress would reduced cytochrome path way role and increased alternative pathway participation degree. When respiratory rates of both genotypes are increased significantly, the contribution of TCAC of both genotypes was higher than that in early stage. The inhibiting effect of indoacetate counted for 91.35%-97. 86% of total respiratory rate, but EMP contribution was seriously decreased by potassium deficiency. Increase of the alternative pathway and residual respiration of Weiyou 35 by stress was less than that of Shanyou 6. PPP activity of Weiyou 35 was always lower than that of Shanyou 6. It is suggested that genotype tolerant to potassium deficiency had its characteristics in respiratory metabolism.

Key words: hybrid rice, potassium deficient stress, respiratory metabolism

关键词: 杂交水稻, 低钾, 胁迫, 呼吸代谢, 水稻