Potassium and sodium and sugar beet yield

They can both play an important role in the regulation of water within the plant via controlling water loss from the stomata on the leaf surface. Potassium controls the ionic concentrations inside plant cells and the transport of sucrose to the root. 

Plants deficient in potassium are characterized by leaves with small brown necrotic spots appearing first in the margins and in severe conditions spread all the way to the midrib, but not involving the veins. 

Sugar beets have a large uptake of potassium and sodium and these elements are interchangeable i.e. one can replace the other. The sugar beet crop removes up to 100 kg K / ha in the roots, however the recommendation for application is lower as trials do not give a response at this level. The need for applications and the rate will depend on the soil type and its store of potassium. This can be determined by soil analysis. Potassium is normally applied together with the nitrogen or before sowing. 

As mentioned, sodium like potassium, plays an important role in the regulation of water within the plant by controlling the ionic concentrations inside plant tissues, including the stomata. Transport of sucrose to the root is also promoted by sodium.

Low levels of soil sodium tends to be in regions where annual precipitation exceeds evaporation and causing rapidly leaching from the soil. In climates where evaporation exceeds precipitation, sodium can accumulate in soil and can reach concentrations that damage crops.

Where sodium levels are low responses have been demonstrated in trials.