Response of three varieties of cigar-filler tobacco under increasing levels of applied nitrogen and irrigation water [Philippines]

Soil moisture regimes differed considerably among irrigation and nitrogen treatments. Soil moisture potential (SMP) of the 0 to 45 cm soil depth during vegetative stage until maturity were at more favorable range in 0.65 Etp [total pan evaporation] than in 0.25 or in 0 Etp irrigation treatment. Likewise, SMP in unfertilized soil appeared to be higher than in fertilized soil. Rooting pattern in Javiz, Simmaba and Vizcaya [varieties] varied in their penetrations depth and rooting density. Vizcaya had more proliferated and deeper root system than the other varieties. The 0.65 Etp irrigation combined with 80 or 120 kg/ha nitrogen produced a finer and well proliferated root system that may have enhanced significantly greater soil moisture and nutrient utilization in the deeper soil layers. Significant interaction between irrigation, applied nitrogen and variety was observed on most growth, yield and leaf quality parameters. Plant height, number of leaves, yield, grade index and crop value index were greatest in 0.65 Etp x 80 kg N/ha for Javiz and 0.65 Etp x 120 kg N/ha for Simmaba and Vizcaya. Leaf area and number of leaves were highest in 0.65 Etp x 120 kg N/ha for Simmaba and 0.65 Etp x 80 kg N/ha for Javiz and Vizcaya. Regardless of variety, specific leaf weight (SLW) decreased with increasing levels of irrigation. It decreased with increasing levels of nitrogen until 80 kg N/ha for Javiz and Vizcaya, and 120 kg N/ha for Simmaba. Irrigation and nitrogen fertilization affected leaf quality. Reducing sugar, N and K leaf concentration decreased with increasing amount of irrigation regardless of varieties. Nicotine and N leaf concentration increased linearly with increasing nitrogen rate while K leaf concentration showed the contrary. In addition, leaf combustibility was inversely related to increasing levels of applied irrigation in Vizcaya variety. It increased with increasing amounts of applied nitrogen up to 80 kg N/ha then declined in Javiz. Variations of leaf combustibility with levels of irrigation and nitrogen were not distinct in the other varieties.