Potassium nutrition and frost tolerance of potato genotypes

Abstract

Abstract Six potato genotypes were tested to evaluate the effect of K nutrition on frost tolerance by measuring electrolyte leakage from leaves exposed to various freezing temperatures. Potato genotypes were selected through the known range of low temperature survival tolerance within tuber‐bearing Solanum species. An experiment was conducted using a soil high in K; and then nutrient solution experiments were conducted in the open environments of La Molina. Commercial K fertilizers, at different levels, were unable to increase significantly the frost tolerance in a common potato cultivar grown in a soil high in K. In nutrient solutions experiments, with plants grown without any hardening process, we found that there is a genetically related capacity to respond through K nutrition to increase frost tolerance among potatoes. The common commercial potato, S. tuberosum, did not change significantly its freezing sensitivity when K nutrition was varied. But S. curtilobum, which is grown by low income farmers in the Titicaca Lake area of Bolivia and Peru, especially reduced its sensitivity to frost tolerance when submitted to K deficiency by as much as 1.5 to 2°C. Leaf free proline does not accumulate as a result of K deficiency but all the K deficient plants had lower amounts of free proline. The K deficient plants also showed a lower induced nitrate reductase activity.