The responses of two wheat cultivars to salinity stress regarding phosphorus uptake and sitribution were evaluated in a greenhorse experiment using a complete randomized block design with factorial treatments in three replications. Salinity treatments were comprised of three levels of saline water used for watering. These included solutions of zero(SO),2.5 (SI) and 5.0 (S2) g/l NaCl (equivalent to zero tap water,43 and 85.5 mM NaCl respectively) , the application of which started starting from 25 days after sowing.
Phosphorus content of plant organs, in five different growth stages, were detemined using molibdovanadate colorimetric method, measurements being made by a spectrophotometer. The results showed that p uptade was reduced and its distribution pattern changed by increase in salinity .
The accumulation rate of p in leaves was higher while in main stem and tillers it was lower with salinity , along with p redistribution percentage being decreased in leaves while increased in main stem and tillers. Phosphorus concentration and content of grains were increased and decreased respectively with increase in salinity. Some significant differences were observed between the two cultivars used.
In non- resistant lina -66 cultivar the rate of p uptake (p content in shoot) reached a maximrm at maturity a considerable reduction of uptake being observed with increase in salinity. But in salt- resistant Tabasi cultivar p uptake by the shoot increased up to maturity stage,reaching a maximum that was 40,68 and 90 percent higher than Inia-77 at SO,S1 and S2 levels respectively. Although the rate of redistribution in Inia-66 was higher and increased with salinity, this puocess was more efficient in Tabasi because of higher p accumulation in main stem and tillers. It seems that, regarding the key role of p in metabolic processes , the uptake and distributation of this macroelement could be considered as a parameter closely related to salinity resistance in wheat.
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