Performance of conventional and enhanced-efficiency nitrogen fertilizers on potato tuber mineral composition and marketability.

BACKGROUND: Potato is an essential crop for global food security, and its cultivation requires a significant amount of readily available nitrogen (N) to ensure tuber quality. Therefore, managing N with enhanced-efficiency fertilizers becomes a potential strategy to meet the seasonal potato N demand. A 3 site-years (SYs) study was conducted to assess the marketable attributes and mineral composition of table-stock potato in response to N rates and fertilizers urea, ammonium sulfate and ammonium sulfate nitrate (ASN) with nitrification inhibitor dimethylpyrazole phosphate (DMPP). RESULTS: At 75% of recommended N rate (RNR), ammonium sulfate and ASN+DMPP ensured marketable tuber yields equivalent to that observed at 100% of RNR. Urea promoted greater tuber K and Mg concentrations than ammonium sulfate and ASN+DMPP. Although inconsistent across SYs, ASN+DMPP generally reduced starch and reducing sugars contents and increased pulp pH and protein content than other fertilizers. Increasing N rates from 50% up to 75% and 100% of RNR increased marketable tuber yields and protein content, whereas soluble solids increased from 50% to 100% of RNR. Conversely, increasing N rates from zero to 75% of RNR reduced tuber firmness, whereas N application reduced tuber P concentration, regardless of N rates. CONCLUSION: Although ASN+DMPP showed potential for increasing marketable tuber yield and protein content, potatoes receiving ammonium sulfate and ASN+DMPP lowered tuber K and Mg concentrations compared to those receiving urea. Overall, potato tuber quality improvements are N source-specific, demanding strategies under which these fertilizers can ensure/improve tuber nutritional composition along with size quality. © 2021 Society of Chemical Industry.

Physico-chemical properties of starches isolated from potato cultivars grown in soils with different phosphorus availability.

BACKGROUND: Starch is the major component of potato tubers, amounting approximately to 150-200 g kg (-1) of the tuber weight. Starch is considered to be a major factor for the functionality of the potato in food applications. This study evaluated the physical characteristics of potato starches isolated from tubers of different potato cultivars grown in soil with three levels of phosphorus (P) availability. All potatoes were growing according the same method. The starches were isolated by physical methods and the samples were analyzed for the amylose, P content, paste properties (RVA) and thermal properties of gelatinization and retrogradation (DSC). Experimental data were analyzed considering the potato cultivars and the three soil P availability. RESULTS: For all measured parameters significant impact of cultivar and soil P availability was determined. Phosphorus contents in potato starches ranged from 0.252 to 0.647 g kg(-1) and amylose from 27.18 to 30.8%. Starches from different potato cultivars independent of soil showed a small range of gelatinization temperature. All starches showed low resistance heating and shear stress. CONCLUSION: The results showed the influence of growing conditions (soil P availability) and also of the differences between the potato cultivars on important characteristics of applicability of starches.