Abstract
The objective of this study was to determine the effects of potassium fertilization (applied to soil at 150, 250, and 350 kg K2O ha−1) and irrigation on the yield (fresh matter yield and dry matter yield of above-ground biomass and tubers) and the health status of tubers and leaves of three Jerusalem artichoke—JA (Helianthus tuberosus L.) cultivars (Topstar, Violette de Rennes, Waldspindel). The Topstar cultivar was characterized by the highest total tuber yield (60.53 Mg FM ha−1) and the highest above-ground biomass yield (65.74 Mg FM ha−1). An increase in the rate of potassium fertilizer to 350 kg K2O ha−1 did not affect total tuber yields. The greatest increase in above-ground biomass yields was observed in response to the potassium fertilizer rate of 150 kg K2O ha −1 (64.40 Mg FM ha−1). Irrigation increased tuber yields by 59% and above-ground biomass yields by 42% on average. Phytopathological analyses revealed that JA leaves were most frequently colonized by fungi of the genera Alternaria, Fusarium, and Epicoccum. Alternaria and Fusarium fungi were more prevalent in non-irrigated than in irrigated plots. A higher number of fungal pathogens was isolated from the leaves of cv. Violette de Rennes grown in a non-irrigated plot fertilized with 250 kg K2O ha−1. Tubers were most heavily colonized by fungi of the genera Penicillium, Fusarium, Alternaria, Botrytis, and Rhizopus. Fungal species of the genus Fusarium were isolated from tubers in all irrigated treatments, and they were less frequently identified in non-irrigated plots. Only the tubers of cv. Topstar grown in non-irrigated plots and supplied with 150 kg K2O ha−1 were free of Fusarium fungi. The number of cultures of pathogenic species isolated from Jerusalem artichoke tubers had a minor negative impact on fresh and dry matter yield.
Highlights
Jerusalem artichoke (JA) has been long grown as a source of animal feed, but in recent years, its popularity increased in the food processing industry, mainly in the production of functional ingredients such as inulin, oligofructose, and fructose [1,2,3,4]
In non-irrigated treatments, fungal pathogens were most frequently isolated from the leaves of cv
Potassium fertilizer applied at the optimal rate of 150 kg K2O ha−1 contributed to the greatest increase in the above-ground biomass yield of JA
Summary
Jerusalem artichoke (JA) has been long grown as a source of animal feed, but in recent years, its popularity increased in the food processing industry, mainly in the production of functional ingredients such as inulin, oligofructose, and fructose [1,2,3,4]. JA tubers have been recognized as a valuable source of sugars for bioethanol production. Macronutrient deficiencies, including nitrogen, potassium, and phosphorus, as well as drought compromise yields [8,14,16,17,18,19,20]. Nitrogen has a stronger influence on yields than potassium because it determines the photosynthetic potential of plants and increases their water use efficiency [21]. Potassium and nitrogen fertilization increases the yield of tubers and improves their quality [22]. Research indicates that early-maturing varieties are more sensitive to drought that late-maturing varieties For this reason, drought as well as nitrogen, phosphorus, and potassium (NPK) fertilizers strongly influence the accumulation of dry matter [23,24]
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