Yield and phenology of yam as affected by the physiological rest period of seed-rhizomes

Abstract

The objective of this work was to evaluate the effects of the rest period of seed-rhizomes in the phenology and yield of yam Da Costa (Dioscorea cayennensis). The experiment was carried out in field conditions at the Federal University of Paraíba, in Areia, Brazil, from January to December 2004, in an Ustpsamment soil. A completely randomized block design was used to test three treatments, 60-, 80-, and 100-day seed-rhizome rest periods, with seven replications. Plant emergency was evaluated every ten days from 40 to 90 days after planting (DAP), as well as plant height, evaluated up to 80 DAP. The average mass of commercial rhizomes and the yield of commercial and seed-rhizomes were also assessed. At 40, 50, and 60 days after planting, plant emergency was superior for seed-rhizomes submitted to 100-day rest periods. At 70 and 80 DAP, there were no significant differences. At 90 DAP, seed-rhizomes that rested for 60 and 100 days provided around 91 and 83% of plant emergency, respectively. Concerning plant height, seed-rhizomes that rested 100 days produced the tallest plants. The average mass of commercial rhizomes and the yield of commercial and seed-rhizomes were 1.22 kg, 13.1 t ha-1, and 7.7 t ha-1, respectively, for seed rhizomes submitted to 60-day rest periods. For 100-day rest period rhizomes, the average mass of commercial rhizomes and the yield of commercial and seed-rhizomes, were 0.73 kg, 7.7 t ha-1, and 1.7 t ha-1, respectively.