Effect of Potassium Fertilization on Quality of Potato (Solanum tuberosum L.)

Abstract

A screen house was conducted to evaluate the effect of applied potassium (K) (0 and 60 kg K2O ha-1) on potato quality parameters planted on 30 different surface (0-15 cm) soils. The field experiments including five levels of K (0, 15, 30, 45, 60 and 90 kg K2O ha-1) were also conducted at four field sites to validate the results obtained from the pot study. Tuber yield, uptake and quality parameters include tuber size, reducing sugars content, tuber color and specific gravity were studied. The results from pot study showed that the tuber yield and uptake increased significantly with addition of 60 kg K2O ha-1 in one-third and one-fourth of the 30 soils whereas tuber size did not show significant increase with the K application of 60 kg K2O ha-1 compared to no K. The reducing sugar content of tubers also showed inconsistent significant decrease with K application. The one-third samples showed negative impact of applied K on the reducing sugars. The reducing sugar weakly but significantly correlated with tuber K uptake (R2=0.141). Tubers received K application were significantly lighter (L) in colour compared with tubers without K. The inconsistent significant effect of K application on specific gravity in all soils were reported. In field experiments, similar inconsistent response of K on plant indices and quality parameters were measured. The results suggest that K addition in soils with low, medium and high exchangeable K causes negative influence on crop yield and its quality.