Absorption of Nitrogen Dioxide by Sunflower Plants Grown at Various Levels of Nitrate

Abstract

SUMMARYThe effect of varied levels of nitrate on the absorption of atmospheric nitrogen dioxide (NOj) by sunflower {Helianthus annus L.) plants was investigated by using a ^^N dilution method. Growth of the plants was greatest at 5 mM nitrate, with less growth at 15 mM nitrate and a considerable reduction at zero nitrate. The total amount of NOj-nitrogen absorbed by the plant depended on the plant size and total leaf area.Nitrate supply did not influence the rate of absorption of NOg by the plants when exposed to 0-3 /i\ r^ NOg. On the contrary, when the plants were exposed to 2-0 /il T^ NOg, the absorption rate was significantly lower for the plants grown at zero nitrate compared with those grown at 5 or 15 mM nitrate. The lower rate of NOg absorption in the nitrate-deficient plants was not due to the changes in stomatal resistance or stomatal density of the leaves, but could have been due to an increase in mesophyll resistance resulting from accumulation of high levels of nitrite in the leaf tissues.Nitrogen dioxide at 0-3 /i\ \'^ exerted a nutritional effect on the nitrate-deficient plants, while NO2 at 2-0 ju,\ T^ acted as a toxic air pollutant on the plants at all the levels of nitrate supplied.

Stable isotope analysis reveals differential effects of soil nitrogen and nitrogen dioxide on the water use efficiency in hybrid poplar leaves

“…This is in agreement with Rooney (1994), and Stitt & Schulze (1994), who describe an increased carbon investment into the foliage at high N availability. The same effect has been observed for Helianthus annuus (Okano & Totsuka, 1986) and Picea abies (Muller et al, 1996).…”

Interaction between atmospheric and pedospheric nitrogen nutrition in spruce (Picea abies L. Karst) seedlings

“…This would indicate that NO2 uptake represented up to about 18% of the plant N uptake and tended to decrease with time. By comparison, Okano & Totsuka (1986) found that this value was about 12% in sunflower grown at 300mm''m""* of NO2 in the atmosphere for 7d. Recently, using '''NO2, Nussbaum et al (1993) found that atmospheric N nutrition of 6-year-old spruce trees represented about 10% of the plant N budget when fumigated at 60 mm'' m"-' for4d under continuous light.…”

Role of Foliar Fertilization on Plant Nutrition

“…Okano and Totsuka (1986) used the 15 N dilution method for quantitative assays of N0 2 absorbed by sunflower and maize leaves and studied the influence of nitrate nutrition of the plants on foliar N0 2 absorption. They found that the amount of N0 2 absorbed increased with the concentration of N0 2 .…”