Agronomic performance and nutritional status of arrowroot in response to nitrogen fertilization with bovine manure
Arrowroot is a plant little studied in terms of fertilization and nutritional status. This study evaluates the effect of nitrogen fertilization with bovine manure on the nutritional status of arrowroot plants by means of physiological indices, on yield, and on the export of nutrients by rhizomes of two arrowroot varieties. The experimental design was a randomized block design in a 2 x 6 factorial scheme, with four replicates. Factors consisted of two arrowroot varieties (‘Comum’ and ‘Seta’) and six nitrogen rates (0, 75, 150, 300, 600, and 900 kg ha-1). At 120 days after planting, the following were evaluated on the second fully expanded young leaf in the main stem: SPAD Index, chlorophyll Index, flavonoid Index, nitrogen balance, and leaf nutrient content. The SPAD and chlorophyll indices correlated positively with total leaf N content and commercial rhizome yield, but there was no significant difference between varieties. The SPAD 502 and Dualex readings were efficient in diagnosing N status in arrowroot plants. Commercial rhizome yields were 47.9 t ha-1 for variety ‘Seta’, with 778 kg ha-1 N; and 43.2 t ha-1 for variety ‘Comum’, with 900 kg ha-1 N.