Some physiological and biochemical differences between salt tolerant and sensitive rice (Oryza sativa L.) genotypes in response to salinity.
1988
Zongil Wang | Quijie Dai | Xiaozhong Liu | Zhixia Wang | Jiankuen Li
The physiological and biochemical effects of salinity on rice plant were studied during 1985-1987 at Jiangsu Academy of Agricultural Sciences, China, using three rice genotypes, "80-85" (salt-tolerant), "83-85" and "83-51" (salt-sensitive). It was found that the drastic reduction of net photosynthetic rate (Pn) caused by salinity stress in susceptible variety was due to higher stomatal resistance (Rs) and lower relative water content (RWC), resulting in greater growth inhibition. The higher K:Na ratio in salt tolerant genotype indicates its greater capacity to adapt to salinity and suggests that the excessive accumulation of Na is the major cause of injury to rice under salt treatment. The content of malonyldialdehyde (MDA) is highly correlated with plasmalemma permeability. MDA accumulation induced by higher activity of peroxidase occurred before the appearance of salt injury symptoms in younger leaf and much more in the sensitive genotypes. However, the increase in peroxidase activity is not proportional to the increase in plasmalemma permeability and MDA accumulation. The quantity of nucleic acids is reduced sharply with prolonged salinity treatment and RNA synthesis appeared to more sensitive to salt stress than the synthesis of DNA. The activity of RNase in sensitive genotype is much higher than that of the tolerant one. There is a positive relationship between the amount of protein and RNA, while a negative correlation was found between the activity of RNase and the level of RNA. The protein to RNA ratio is similar in both tolerant and sensitive genotypes, indicating similar effectiveness of their RNA in protein production. The ratio of RNA to DNA reflecting the activity of DNA is higher in salt tolerant genotype.
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