Vliyanie defitsita azota na fotokhimicheskuyu aktivnost' khloroplastov pshenitsy i ikh ustojchivost' k dejstviyu sveta vysokoj intensivnosti.
1995
Polesskaya O.G. | Alekhina N.D.
Wheat plants grown at various nitrogen levels were used in studies on the leaf chlorophyll a and b content, chloroplast photosynthetic activity and the resistance to inhibition by high intensivity light. The wheat (variety Zarja) was grown for 30 days in the 1/2 strength Knop solution containing 6 mM NO3 (+N treatment) or without nitrate (-N treatment). In both cases the leaf ontogeny was retarded, and the fresh weight, and the chlorophyll particularly chlorophyll a content was decreased, the decrease was more pronounced in plants kept without nitrogen. The activity of chloroplasts was estimated from the rate of oxygen evolution in the Hill reaction with ferricyanide and expressed on a chlorophyll basis. It was the same for both chloroplast preparations. It slightly decreased during leaf ontogeny. Illumination of chloroplasts by strong light (10**5 erg/sm**2 sec) for 5; 10 and 15 min inhibited the process of oxygen evolution and the effect was more pronounced in -N treatment chloroplasts. The increase in chloroplast sensitivity to strong light is probably one of the early plant responses to nitrogen starvation.
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