STUDIES ON ORGANIC MATERIALS FOR THE PRODUCTION OF MODIFIED ATMOSPHERE FOR MAIZE WEEVIL CONTROL IN STORED MAIZE

摘要

Experiments were conducted in a laboratory and in storage structures in the field between 2008 – 2009, to assess the amount of the CO2 and O2 produced and the modified atmospheres produced (gas mixtures) as protectants of maize grains against the maize weevil (Sitophilus zeamais Motsch.).The production of modified atmospheres (MAs) by composting fresh cow dung, chopped fresh sugarcane and chopped dry maize stubble each wetted at 60% moisture content was studied. The MAs were produced in plastic cans (bio-generators). The measurement of the MAs produced using Riken Infrared Gas Analyzer, Model RI-550A for CO2 and portable oxygen meter for O2 indicated that the highest CO2 levels were produced in fresh cow dung (25%) and fresh sugarcane (23%) following 48hr incubation period. These substrates gave the lower O2 content (3.5% and 3.7%, respectively) compared to the dry maize stubble which resulted in lower CO2 level (9%) and the highest O2 content (19%). The efficacy of the MAs produced by these substrates was also studied in simulated storage structures in the field by letting the produced gas mixtures to storage structures containing 3 quintals of weevil susceptible BH-540 maize variety. Analysis of variances showed that application of modified atmosphere to the maize grains stored in airtight storage structures can effectively control maize weevils. Significantly (p0.01) higher mean numbers of weevils mortality and lower mean number and weight of damaged grains and weight losses were recorded in maize grains treated with Quickphose (fumigant standard check) and modified atmospheres from fresh cow dung and fresh sugarcane. The gas produced from the digestion of fresh cow dung and fresh sugar cane significantly (p0.01) reduced the progress of maize weevils infestation. Germination test did not show any variation among the treatments. The result of this study showed that the gas from biological digestion of fresh cow dung and chopped sugar cane can be used as control option for maize storage pest in airtight storages. However, rate and frequency of application and economic feasibility should be studied before commercial application of the technique.