Terrestrial arthropod profile and soil microbial population dynamics on cabbage cropping as affected by application of Trichoderma microbial inoculant (TMI) in Quezon, Sariaya, Philippines

Abstract

A two-season study was conducted in a cabbage farmer’s field in Sariaya, Quezon Province, Philippines to determine the impact of Trichoderma microbial inoculant (TMI) application on above-ground terrestrial arthropod profile. Soil microflora population dynamics, soil chemical properties, the nitrogen and phosphate crop uptake, and disease incidence were monitored for the first season only. TMI treatment was compared with farmer’s practice (FP, control) that involved insecticide treatment following an RCBD with three replicates. Target organisms were simultaneously monitored at 40, 60 and 85 days after transplanting (DAT). This is the first report on simultaneously studying these components of the cabbage agroecosystem. Combined seasons’ data showed higher arthropod counts in TMI plots, with predators significantly higher at third sampling-first season and parasite population first samplingsecond season. Insect damage was observed on all plants indicating herbivore infestation, despite insecticide spraying in FP. Marketable yield was significantly greater in TMI plots based on combined seasons’data. Trichoderma invaded cabbage roots and existed as an endophyte throughout the life of the crop. It also significantly reduced disease incidence, increased N uptake despite reduced fertilizer application compared with FP. No change in culturable bacterial and fungal population was observed except for a transient increase in fungal population following TMI application. Further testing on other crucifers should be done to determine their reaction against major insect pests and on functional microbial groups.