ABSTRACT
The effects of irrigation, plant density and inorganic fertilization on the yield, mean weight, length and diameter of yam (Dioscorea cayennensis L.) tubers were studied. In Experiment 1 three irrigation regimes (levels equivalents to 50, 75 and 100% of class A pan evaporation, at irrigation intervals of 3, 4 and 5 days, respectively) were tested, two plant densities (13.889 and 10.417 plants ha-1) and four nitrogen levels (0, 50, 100 and 150 kg.ha-1 of N) in split-split plot design. In Experiment 2 the same irrigation levels, but in intervals of 3, 5 and 7 days, were tested in ten treatments NPK (50-60-60, 50-120-60, 50-180-60, 100-60-60, 100-120-60, 100-180-60, 150-60-60, 150-120-60, 150-18060 and 100-120-0 kg.ha-1) in the split plot design. The density of 13.889 plants.ha-1 (1.20m x 0.60m) associated to 100 kg.ha-1 of N + 120 kg.ha-1 of P2O5 + 12,500 kg.ha-1 of farm yard manure may be recommended for the irrigated yam crop; the irrigation with a water level equivalent to 75% of class A pan evaporation, at five day intervals, promoted satisfactory results of productivity, mean weight, length and diameter of the yam.
Key words:
Dioscorea cayennensis; plant density; pan evaporation; water level