Potassium and nitrogen poising: Physiological changes and biomass gains in rice and barley

Abstract

Britto, D. T., Balkos, K. D., Becker, A., Coskun, D., Huynh, W. Q. and Kronzucker, H. J. 2014. Potassium and nitrogen poising: Physiological changes and biomass gains in rice and barley. Can. J. Plant Sci. 94: 1085–1089. Soil nitrogen, potassium, and water are three of the most important factors influencing, often interdependently, the growth of plants. Maximizing plant growth is not simply a matter of maximizing the availability of these and other nutrients; indeed, excess supply can be deleterious to plant performance. Rather, optimal performance may come about by adjusting the supply of each of the disparate factors required for plant growth, not only individually, but in relation to one another. In our work investigating the nutritional maximization of plant growth, we have found that altering the ratios of N and K provided to seedlings of cereal grasses can result in very substantial increases in vegetative biomass accrual, e.g., >220% of low-K+ controls, in short-term studies with rice, the world's most important cereal grain, and even greater gains in grain yield, in the longer term. Hence, the findings in our laboratory are of direct relevance to the aim of NSERC's Green Crop Network, which was to contribute to the amelioration of climate change by improvement of carbon capture and sequestration in crop plants. In addition, these findings may help to increase the world's food supply, the security of which is sometimes at odds with proposed means to thwart climate change. Our work in this area has also led to a potential breakthrough of a more fundamental sort in plant nutritional biology, which may in itself have important practical implications: evidence that aquaporin-type transport proteins conduct rapid NH3 fluxes into roots at toxic levels of external ammonia/ammonium.

The nitrogen–potassium intersection: membranes, metabolism, and mechanism

“…; Britto et al . ). This is important in part because of the current public reaction against recombinant DNA technology, particularly in Europe.…”

“…Moreover, the world's most important crop species, rice, is also the world's most water consumptive, further highlighting the necessity to understand and optimize plant water use (Hoekstra & Chapagain 2007;Chapagain & Hoekstra 2011;Britto et al 2014). While the complexities of nutrient sensing, signalling mechanisms and transport regulation cannot be fully unravelled without the benefits of molecular biology, there is still much room for physiological methods in the pursuit of more efficient and productive crop systems (Pettigrew 2008;Cramer et al 2009;Britto et al 2014). This is important in part because of the current public reaction against recombinant DNA technology, particularly in Europe.…”

“…Subsequent work has shown that, under these low-affinity NH 4 + -transport conditions, the major transported species may in fact be the deprotonated, uncharged ammonia molecule (NH 3 ), which crosses the plasma membrane via aquaporins (Jahn et al 2004;Coskun et al 2013b). The ability of elevated [K + ] ext to greatly diminish transport via aquaporins may reflect the significance of this ion in the area of plant water relations (Quintero et al 2007;Britto et al 2014;see succeeding text).…”

“…This is an important new development because conditions arise that exclude AKT1 and NRT1.1 in high-affinity K + and NO 3 À uptake,respectively (e.g. under conditions where high-affinity HAK transporters are functional Coskun et al 2013aCoskun et al , 2014 or where high-affinity NRT2 transporters predominate Wang et al 2012)). The apparent coupling of K + and NO 3 À transport in the xylem (Section on Transport) appears to play out at the molecular level as well.…”

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

“…In contrast, potassium fertilizer application has received less attention and is typically insufficient in many developing countries (Zhang et al ). Overall, the imbalance between N and K fertilizer application significantly reduces crop biomass and limits yield potential (Britto et al ). Previous studies have documented that rational N and K fertilizer application can stimulate crop yield and fertilizer use efficiency in cotton (Dong et al ), and in canola and wheat (Brennan and Bolland ).…”