Studies On Methyl Bromide Alternatives Of Greenhouse Tomato

Study on methyl bromide alternatives of greenhouse tomato was carried out in 2002-2003 to control soil-borne diseases.The alternative techniques and methods include using soil fumigants metham sodium and sulfuryl fluoride,solarization combinated with bio-control agent (BCA) and planting with substrate.The field trials were conducted together with using drip irrigation system and polyethylene film.Results indicated that metham sodium and sulfuryl fluoride were effective replacements for methyl bromide and solarization combined with BCA and substrate were noneffective.Fusarium spp. populations in treated plots were significantly lower than untreated plots during 4 months' survey.Results indicated that methyl bromide,metham sodium and sulfuryl flulride fumigation had good efficacy and soil solarization combined with BCA were not very effective in the first analysis after treating.Reduction rate of Fusarium spp.of methyl bromide,metham sodium,sulfuryl fluoride and solarization were 100%,91.8%-99.0%,44.4%-98.3% and 18.8%,respectively. Fusarium spp. populations began to increase since the second analysis. Beneficial fungi Trichoderma spp.populations also decreased rapidly after treating but recovered partially in most of the treatments after 4 months.Metham sodium 35g/m2-52.5g/m2 and sulfuryl fluoride 25g/m2-50g/m2 had good efficacy on controlling root-knot nematodes whereas soil solarization combined with BCA and sulfuryl flulride 12.5g/m2 were noneffective.Total nematodes and root-knot nematodes populations decreased markedly after treating but total nematode populations soon increased. Root-knot index among different treatments were significantly different..Vigour of tomato such as plant height and stem diameter were accelerated in different degree.The most effective treatments were metham sodium 35g/m2,sulfuryl fluoride25g/m2 and metham sodium 35g/m2 whereas substrate,soil solarization combined with BCA and sulfuryl fluoride 12.5 g/m2 were not so effective.Methyl bromide fumigation and its alternatives improved tomato yield with the range of 7.46%-34.05%.The treatments with the highest yield were metham sodium 35g/m and sulfuryl flulride 50g/m2 and the lowest is soil solarization combined with BCA and sulfuryl fluoride 12.5 g/m2.Untreated plots produced more unmarketable fruits than the other treatments. Fruit number, fruit weight of single plant and single fruit weight in treated plots were lower than untreated plots.Analysis on economic results of different treatments indicated that every treatmentsmade profit except substrate treatment.The profit of methyl bromide, metham sodium, sulfuryl fluoride and solarization combined with BCA were 12657yuan, 3279yuan -17841yuan, 6440yuan-9516yuan and 912yuan per hectare,respectively. Substrate treatment had no significant profit in one crop season because it need very high one-off investment. Substrate can be used repeatedly and has benefit on environment so it has very good foreground for applying.Investigation in 2003 indicated that methyl bromide alternatives still had good efficacy on the succedent crop. Vigor of cucumber were markedly advanced.Plant height was significant different in various treatments.Average plant height of untreated plots was the shortest with 55.4cm and that of metham sodium 35g/m2 treatment was the highest with 85.2cm.This results were similar to the former crop tomato.Soil fumigation affected soil chemical characteristics such as the content of NH4+-N ,NO3-N and pH of soil.Organic matter, Available phosphorus, Available Kalium and Organic carbon were not affectd.The study indicated that fumigating with sulfuryl fluoride could effectively control soil-borne pathogens,remarkably improve crop yield ,thereby having great potentialities to replace methyl bromide as soil fumigant.Fumigating with metham sodium also acquired good results. Applied dosage of sulfuryl fluoride and metham sodium should be 25g/m2 and 35g/m2,respectively.Soil solarization combined with BCA was not very effective so it is needed to continue to r...