Potassium rate and source effects on potato yield, quality, and disease interaction

Cracking and fracture properties of potato (Solanum tuberosum L.) tubers and their relation to dry matter, starch, and mineral distribution

BACKGROUND

Potato disorders lead to a significant reduction in the yield and quality of marketable tubers. Thumbnail cracks are physiological tuber skin disorders that can significantly affect the tuber's appearance and, hence, the overall quality. The aim of this study was to characterize fracture properties of the tuber skin. Knowledge of the physiological reasons that influence the resistance of potato tubers to mechanical impacts and thus to cracking and fracturing is limited. Tuber dry matter (DM) and starch content were found to correlate with the rheological properties of tubers, which, in turn, could affect the resistance of the tubers to cracking and fracturing. Moreover, divalent cations, such as calcium (Ca) and magnesium (Mg), and their distribution in the tuber can affect the tuber's resistance to mechanical impacts via cell-wall stabilizing properties.

RESULTS

Tubers with higher DM, starch, and Ca concentrations exhibited the highest resistance to mechanical impacts.

CONCLUSIONS

The reason for the increased resistance of tubers with higher DM and starch concentrations to mechanical impacts is assumed to be related to a certain cell structure of these tubers, which is why considerable force is needed to damage the cell structures. The relation between higher Ca concentrations and an improved resistance of tubers to mechanical impacts is assumed to be connected with the role of Ca in linking cell-wall polymers and thus stabilizing the cell wall. © 2018 Society of Chemical Industry.

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.