[Physiological characteristics of rice seedlings roots under aluminum stress]

A hydroponic experiment was conducted with the four-leaf stage seedlings of aluminum (Al)-susceptible rice variety IR24 and Al-tolerant rice varieties Jingyou 725 and Liangyoupeijiu to study the physiological characteristics of the seedlings roots under effects of 0, 0.5 mmol x L(-1), and 7.5 mmol x L(-1) of Al. Under the stress of 7.5 mmol Al x L(-1), Al-tolerant varieties had a far lesser decrement of root vigor than Al-susceptible variety, while the Al-susceptible variety had a higher root mitochondria H2O2 content than Al-tolerant varieties. Al stress induced a lesser increment of CAT activity in the root mitochondria of all tested varieties. With the increasing Al concentration, the root mitochondria POD activity of IR24 and Jingyou 725 decreased after an initial increase while that of Liangyoupeijiu was increasing, and the root mitochondria APX activity of IR24 decreased after an initial increase while that of Jingyou 725 and Liangyoupeijiu was increasing. The root glutamic acid content of all tested varieties showed an increase-decline trend, and their citric acid content decreased while PEP content increased. The ratio of cyanide-resistant respiration rate to total respiration rate of Al-tolerant Jingyou 725 and Liangyoupeijiu increased obviously, compared with that of Al-susceptible IR24.