Nitrogen or potassium preconditioning affects uptake of both nitrate and potassium in young wheat (Triticum aestivum)

Abstract

Plant uptake rates of nitrate and potassium (K) are under feedback control from plant concentrations of nitrogen (N) and K, respectively. However, there is uncertainty concerning the interactions between nitrate and K uptake. We tested the hypothesis that plant concentrations of N affect K uptake and plant concentrations of K affect uptake rates of nitrate. Two experiments were carried out with wheat. Each consisted of three phases. In Phase 1, the plants were grown in complete nutrient solution for 17-18 days. In Phase 2, nitrate and K treatments were imposed -the plants were either starved of the nutrient or provided excess for 2.5 or 5 days. This generated plants of similar size but with different N and K concentrations. In Phase 3, complete nutrient solutions were restored for all plants and nitrate and K uptake was followed for 8 h. Uptake till the end of Phases 2 and 3 was examined by analysis of variance. Uptake during Phase 3 was also examined using a simple model that included Michaelis-Menten uptake kinetics and feedback control due to whole-plant N and K concentrations, but assumed no interaction between nitrate and K uptake. The model was fitted using Phase 3 measurements of nitrate uptake following nitrate starvation or excess and K uptake following K starvation or excess. There was little influence of plant N on K uptake or of plant K on nitrate uptake for periods that started with adequate plant concentrations of N and K (Phases 1 and 2). However, in Phase 3 when N starvation was broken, the plants took up more K than controls and model predictions, so feedback control of K uptake had been lessened. Similarly, when K starvation was broken, feedback control of nitrate uptake was lessened. If plants had endured both N and K starvation then on release of that they took up more K but less nitrate than predicted by the model. These results support the hypothesis under test, and suggest interactions between the mechanisms that regulate uptake of nitrate and K.

Arabidopsis NRT1.5 Mediates the Suppression of Nitrate Starvation-Induced Leaf Senescence by Modulating Foliar Potassium Level

“…The Mechanisms Modulating Foliar K Level Under Nitrate Starvation K + and nitrate were shown to reciprocally facilitate each other's uptake, and nitrate starvation decreased K + uptake (Ivashikina and Feyziev, 1998;Lu et al, 2005;Reid et al, 2016). These reports are in accordance with our results (Supplemental Figure 6C and 6F).…”

Leaf photosynthetic capacity is regulated by the interaction of nitrogen and potassium through coordination of CO2 diffusion and carboxylation

“…Increasing K fertilizer instead of N in reference to a suitable N/K value caused no marked change in g tot and V cmax or A n , confirming previous studies that excessive K cannot continually boost CO 2 transport ability (O'Toole et al , Jin et al , Lu et al ) and Rubisco activity (Weng et al ). Leaf photosynthetic capacity would not be increased effectively by elevating K nutrition to a threshold value, which is more pronounced under sufficient N nutrition (Reid et al ). As mesophyll conductance and Rubisco contents in leaves are heightened with the increases in N supply (Ghannoum et al , Li et al ), g tot and V cmanx values were higher with increasing N nutrition, as opposed to K, in reference to a suitable N/K ratio.…”

“…activity (Weng et al 2007). Leaf photosynthetic capacity would not be increased effectively by elevating K nutrition to a threshold value, which is more pronounced under sufficient N nutrition (Reid et al 2016). As mesophyll conductance and Rubisco contents in leaves are heightened with the increases in N supply (Ghannoum et al 2005, g tot and V cmanx values were higher with increasing N nutrition, as opposed to K, in reference to a suitable N/K ratio.…”

Increasing Rice Yield Through Amelioration and Fertilization on Medium Freshwater Swampland

“…The response of plants to one nutrient is very dependent on the availability status of other nutrients. Several studies have shown that sufficient potassium nutrients will significantly increase the absorption and utilization of N and P by plants [14] as well as increase the response rate of N and P fertilizer utilization [15]. The application of K fertilizer also increases carbohydrate and N metabolism and therefore increases the quality of plant products [16].…”