Flue-cured tobacco (Nicotiana tabacum L.) and bush sitao (Vigna unguiculata x V. unguiculata) intercrop as influenced by population density, irrigation frequency and NPK fertilization [Philippines]

Population density of bush sitao significantly affected leaf area of intercropped tobacco at the 10th and 15th leaf positions while in intercropped bush sitao, parameters like number of branches, number of pods, green pod yield and seed yield per plant were significantly influenced by population density where 50,000 plants per hectare population was greatly favored. Green pod and seed yield per hectare were significantly highest at 100,000 plant population. Bi-weekly irrigation contributed significantly2048 to the production of larger tobacco leaves on the 15th leaf position while height of bush sitao at 5 WAP, number of harvested pods and green pod yield per plant and green pod yield per hectare were observed significantly higher at weekly interval of irrigation. The effect of the different fertilizer rates was more evident in intercropped tobacco than in bush sitao. Height of tobacco at 60, 75, 90 DAT and at maturity, leaf area on the 15th leaf position and leaf area index at 30 DAT were significantly influenced by fertilizer rate where 100-75-125 kg N, P2O5 and K2O, respectively, was favored. Based on green pod yield, LER and net income did not differ significantly among treatments. However, when LER and net income analyses were based on dried seed yield of bush sitao, significant differences among treatment means were observed. Significant reduction on the LER values was observed on those treatments at 50,000 plant population, irrigated at weekly interval, where land productivity were reduced by 7% and 10% in intercropped plants fertilized with lower rates. However, at higher population, land productivity increased by as much as 38%. On the other hand, higher net income were obtained from intercropping treatments with higher population of bush sitao, although comparable to that obtained from monoculture bush sitao. With respect to monoculture tobacco, net income was comparable to those obtained from treatments with lower populations which were considered among the lo