Effects of potassium supply on limitations of photosynthesis by mesophyll diffusion conductance in Carya cathayensis

Abstract

Potassium (K) influences the photosynthesis process in a number of ways; however, the mechanisms underlying the photosynthetic response to differences in K supply are not well understood. Concurrent measurements of gas exchange and chlorophyll fluorescence were made to investigate the effect of K nutrition on photosynthetic efficiency and mesophyll conductance (g(m)) in hickory seedlings (Carya cathayensis Sarg.) in a greenhouse. The results show that leaf K concentrations < 0.7-0.8% appeared to limit the leaf net CO2 assimilation rate (A), and that the relative limitation of photosynthesis due to g(m) and stomatal conductance (g(s)) decreased with increasing supplies of K. However, a sensitivity analysis indicated that A was most sensitive to the maximum carboxylation rate of Rubisco (V(c,max)) and the maximum rate of electron transport (J(max)). These results indicate that the photosynthetic rate is primarily limited by the biochemical processes of photosynthesis (V(c,max) and J(max)), rather than by g(m) and g(s) in K-deficient plants. Additionally, g(m) was closely correlated with g(s) and the leaf dry mass per unit area (M(A)) in hickory seedlings, which indicates that decreased g(m) and g(s) may be a consequence of leaf anatomical adaptation.

Plant Growth and Photosynthesis Response to Low Potassium Conditions in Three Lettuce (<i>Lactuca sativa</i>) Types

“…In romaine lettuce, both the stomatal conductance and CO 2 concentration of mature leaves were not affected by a reduced potassium concentration. These results suggest the major influence of reduced potassium supply on the photosynthesis of mature leaves in green leaf lettuce and Boston lettuce was a result of non-stomatal limitations, such as a lower capacity of the CO 2 -fixation cycle or a larger mesophyll resistance (Jin et al, 2011;Zhao et al, 2001). The reduction of relative chlorophyll content (Table 1) supported the contention that photochem- Table 2.…”

“…Potassium plays an important role in the photosynthesis process, where it is involved in stomatal regulation, ATP synthesis, and enzyme activation (Lebaudy et al, 2008;Marschner, 1995;Tombesi et al, 1969). It has been suggested that a decrease in photosynthesis is closely connected with a reduced potassium content in the leaves of Chinese hickory (Jin et al, 2011). Potassium deficiency caused a reduction in the photosynthesis and transpiration rates via actuation of stomatal closure in maize (Peaslee and Moss, 1968), thus suppressing plant growth.…”

“…Potassium deficiency caused a reduction in the photosynthesis and transpiration rates via actuation of stomatal closure in maize (Peaslee and Moss, 1968), thus suppressing plant growth. However, non-stomatal reductions of photosynthesis have been reported in potassium deficient plants (e.g., almond tree, Chinese hickory, and cotton), these are associated with a decline in the chlorophyll content, inhibition of PSII activity, and electron transport (Basile et al, 2003;Jin et al, 2011;Wang et al, 2012). Few studies have examined the effects of reduced potassium supply on photosynthesis in lettuce.…”

Foliar Application of Potassium Sulfate Partially Alleviates Pre-anthesis Drought-induced Kernel Abortion in Maize

“…Adequate supplies of K has shown beneficial effects in maintaining or improving dry mass production, leaf area, water retention, and membrane stability as compared to low K nutrition under drought stress conditions (Wang et al, 2013). Similarly, K is essential for cell turgor maintenance via osmotic adjustment (DaCosta and Huang, 2006) and transpiration control via stomatal regulation (Jin et al, 2011) under drought stress. In a hydroponic study, external supply of K in the nutrient medium has been shown to improve drought tolerance in wheat cultivars by improving water potential, chlorophyll contents, gas exchange and an effective reactive oxygen species scavenging (Wei et al, 2013).…”

Potassium-modulated physiological performance of mango plants infected by Ceratocystis fimbriata

“…According to Jin et al (2011) andMarschner (2012), K influences the process of photosynthesis in many ways, e.g. in ATP synthesis, in the activation of enzymes, balance of electric charges required for photophosphorylation and in stomatal opening/closure regulation.…”