Photosynthesis sensitivity to NH₄⁺-N change with nitrogen fertilizer type

Abstract

N-fertilization type affected differently tomato growth. In the field experiment, hydroponic cultures were conducted using NO 3 -N (5 mmol); mixture of KNO 3 -N (3 mmol) and (NH 4 ) 2 SO 4 -N (2 mmol); NH 4 + -N (5 mmol) or urea (5 mmol) as nitrogen source. Compared to nitrate, ammonium and urea had negative effects on morphology and dry matter production. Effects of the different nitrogen forms were investigated by measuring several photosynthesis parameters and chl a fluorescence. Two different significant types of reaction were found. When nitrogen was added as ammonium or urea, dry weight, chlorophyll tenor, transpiration rate, stomatal conductance and photosynthetic activity were inhibited. Supply of ammonium or urea, reduced the ratio (F v /F m ), photochemical quenching and enhanced the non photochemical quenching. These data suggest that the adverse decrease in tomato growth under ammonium or urea supply may be related principally to inhibition of net photosynthesis activity. The high non photochemical quenching shown in tomato fed with ammonium or urea indicated that PS II was the inhibitory site of NH 4 + -N which was directly uptaken by roots, or librated via urea hydrolysis cycle.

Silicon attenuates abiotic stress caused by ammonium toxicity but not nitrogen deficiency in cotton plants

“…In addition, can be absorbed through aquaporins, non‐selective cation transporters and K transporters, increasing the risk of exposure to excess concentrations (Bittsánszky et al., 2015). In this context, the toxicity of results in a lower accumulation of cations such as K, Ca and Mg (Nasraoui‐Hajaji & Gouia, 2014), as observed in this study (Figure 1c–e). Since K + and are very similar in terms of valence and ionic radius, they may not be distinguishable by the membrane‐bound carrier.…”

“…However, has the disadvantage of being toxic depending on its concentration in the culture medium and the tolerance of the plant (Salsac et al., 1987). Among the consequences of toxicity, the decrease in the accumulation of cations such as K, Ca and Mg is notable (Nasraoui‐Hajaji & Gouia, 2014; Schittenhelm & Menge‐Hartmann, 2006). The roots of cotton plants can experience. For example, fertilization with 150 kg/ha of N resulted in 5.5 mmol/L of in the soil solution (Foloni et al., 2006), but in cotton fields, higher doses of N are studied, such as 180 kg/ha (Raphael et al., 2019), which can lead to higher concentrations of in the soil solution.…”

Silicon Supplementation Alleviates Ammonium Toxicity in Sugar Beet (Beta vulgaris L.)

“…Toxic levels of NH 4 + in vegetable tissues are produced when the conversion rate of NH 4 + into amino acids becomes less than the rate of absorption and cellular production for the catabolism of amino acids, nitrate reduction, and photorespiration (Hirel et al 2007). Another consequence of NH 4 + toxicity is that it reduces the accumulation of cations such as potassium, calcium, and magnesium, which are all essential nutrients for plants (Nasraoui-Hajaji and Gouia 2014).…”

Effects of Different Forms and Proportions of Nitrogen on the Growth, Photosynthetic Characteristics, and Carbon and Nitrogen Metabolism in Tomato

“…It was thus concluded that tomato leaves treated with 25%AN:75%NN (T4) or NN: UN (T10–T12) can obtain more light energy and change the direction of light energy absorbed in PSII, which was consistent with the results of Osório et al [ 65 ]. Nasraoui-Hajaji et al [ 66 ] observed that tomato plants receiving ammonium nitrogen or amide nitrogen exhibited lower rates of CO 2 assimilation, stomatal conductance, and transpiration compared to those supplied with exclusively NO 3 − -N as the nitrogen source. Furthermore, the inclusion of nitrate in the nitrogen supply mitigated the reduction in these parameters.…”