NUTRIENT EXTRACTION AND EXPORTATION BY POTATO CULTIVARS: II - MICRONUTRIENTS

NUTRIENT EXTRACTION AND EXPORTATION BY POTATO CULTIVARS: II - MICRONUTRIENTS More productive potato cultivars possibly require larger quantities of micronutrients, but in Brazil there is little information on extraction and exportation of micronutrients by the commonly used potato cultivars. The objective of this study was to evaluate extraction and exportation of micronutrients by the potato cultivars Agata, Asterix, Atlantic, Markies, and Mondial. The experiment was conducted in Itai, Sao Paulo State, Brazil, in the 2008 winter growing season on an Oxisol. Plots consisted of the five potato cultivars and subplots of sampling times (at planting and every seven days after emergence). The cultivars Mondial and Asterix, the most productive, absorbed highest average micronutrient quantities per hectare (71 g B, 122g Cu, 2,228g Fe, 618g Mn, and 405g Zn). Smaller average amounts were absorbed by Atlantic (50, 81, 1,960, 544, and 270 g ha(-1) of B, Cu, Fe, Mn, and Zn, respectively). B demand was highest after tuber initiation, 34 days after planting (DAP), while the Fe and Mn demand was highest between 42 DAP and 63 DAP. Cu and Zn were most absorbed from 64 DAP until the end of the cycle. The exported amounts of B, Cu, Mn, and Zn were cultivar-dependent, in the ranges 48-22 g B, 79-16g Cu, 65-37 g Mn, and 167-83g ha(-1) Zn. Average Fe exportation did not differ among cultivars (243g ha(-1)). The micronutrient quantities absorbed and exported by potato cultivars varied between cultivars, indicating the need of a differentiated fertilization management.