Photosynthetic CO₂Fixation in the Second Leaf of Wheat Seedlings Grown at Different Conditions of Nitrogen Nutrition

The influence of genetic variation and nitrogen source on nitrate accumulation and iso-osmotic regulation by lettuce

“…Assimilated-C concentrations (and associated DM contents) were generally lower in soil-grown plants, with the result that their water concentrations were higher (Table 1). These lower concentrations of assimilated-C in the soil experiment are consistent with reduced proportions of storage-C (mostly starch) often observed in ammonium-fed plants (Hageman 1984;Mehrer and Mohr 1989;Graham 2002;Polesskaya et al 2004), possibly because more carbohydrates were diverted to the roots to provide C skeletons and energy for the assimilation of ammonium (see Reisenauer 1978;Hageman 1984;Feng et al 1998).…”

“…Corresponding differences in the concentrations of the residual assimilated-C (ie structural plus storage-C) were 302 vs 111 gkg −1 DM. As it is unlikely that there were substantial differences in structural-C between plants in the two experiments, this difference would suggest that there was much less storage-C (starch) in the shoots of the plants fed partly on ammonium, an inference consistent with observations on various species (Mehrer and Mohr 1989;Graham 2002;Polesskaya et al 2004). This tendency of ammonium-fed plants to maintain a greater proportion of their carbohydrates in soluble form and less as starch in their shoots, may be a response to the greater demand for a ready supply of the former by the roots to provide energy and C skeletons for the assimilation of ammonium (Reisenauer 1978;Hageman 1984;Feng et al 1998).…”

Redox states of photosystems I and II in irradiated leaves of wheat seedlings grown under different conditions of nitrogen nutrition

“…Inna) seedlings were grown in water culture as described in [11] at different nitrogen availability. In two treatments, the basic nutrient solution (one-fifth the strength of the Hoagland mixture) contained different sources of nitrogen.…”

“…In similarity with a previous study [11], we used the second leaves of wheat seedlings grown on media containing either ammonium or nitrate as a nitrogen source, or the medium devoid of nitrogen. The PSI and PSII redox states were measured either under white light exciting both photosystems or under far-red light, which drives only PSI-dependent alternative electron transport pathways [18,19].…”

“…Both morphological indices (weights of whole plants and individual organs, the weight and surface area of leaves) [5][6][7][8][9] and photosynthetic enzyme activities depend on nitrogen nutrition during plant development. A source, in which nitrogen is available for a plant, significantly affects the development of photosynthetic activity [10,11].…”