Potato plants (Solanum tuberosum L.) are chloride-sensitive: Is this dogma valid?

BACKGROUND: Chloride sensitivity of the potato (Solanum tuberosum L.) cultivars Marabel and Désirée was investigated in two pot experiments (soil/sand mixture and hydroponics). It was tested whether there are differential effects of KCl and K2 SO4 application on tuber yield and tuber quality, and whether both potato cultivars differ in their chloride sensitivity.

RESULTS: Tuber yield, dry matter percentage of the tubers, starch concentration and starch yield were not significantly affected by potassium source (K2 SO4 or KCl). After exposure to salt stress in hydroponics (100 mmol L-1 NaCl, 50 mmol L-1 Na2 SO4 , 50 mmol L-1 CaCl2 ) for 5 days, 3-week-old potato plants had significantly reduced shoot dry mass after NaCl and Na2 SO4 application. However, CaCl2 treatment did not significantly affect shoot growth, although the chloride concentration reached 65 to 74 mg Cl- mg-1 dry matter, similar to the NaCl treatment. In contrast, growth reductions were closely related to sodium concentrations, thus plants suffered sodium toxicity and not chloride toxicity.

CONCLUSION: Both potato cultivars are chloride-resistant and can be fertilised with KCl instead of K2 SO4 without the risk of depression in tuber yield or tuber quality. The statement that potatoes are chloride-sensitive and that chloride has negative effects on yield performance needs reconsideration. © 2017 Society of Chemical Industry.