การคัดเลือกแบคทีเรียและราที่แยกได้จากดินบริเวณรอบรากของปาล์มน้ำมันเพื่อส่งเสริมการเจริญเติบโตของมะเขือเทศและควบคุมราสาเหตุโรคพีช

Abstract

The purposes of this research were to identify the species of oil palm rhizosphere soil microorganisms and to screen bacteria or fungi for their plant growthpromotion ability and antagonism against plant pathogens. Therefore, soil samples from 6 southern provinces of Thailand: Trang, Pattani, Phangnga, Phuket, Songkhla and Suratthani were collected from rhizosphere of oil palm. The results indicated that 280 isolates comprising fungi 186 isolates and bacteria 94 isolates were isolated. Most common microorganisms were Bacillus spp., Penicillium spp., Streptomyces spp. and Aspergillus spp., respectively. The microorganisms from Suratthani province had the most species richness. The isolates from Phuket province had the most species evenness. and the highest species diversity was found in Phangnga province. The microorganisms from Suratthani province were selected to determine the efficiency for promoting plant growth of tomato seed. due to the highest number of microorganisms isolates at 95 isolates The total microorganisms 45 isolates consisted of fungi 25 isolates and bacteria 20 isolates had ability to promote stem and root growth of tomato seeds when compared with control treatment. Then, the 45 isolates were tested for their antagonistic efficiency against 5 isolates of plant pathogens, Fusarium oxysporum, Rhizoctonia solani, Pythium aphanidermatum and Sclerotium rolfsii with dual culture plate method. The most effective antagonist isolates were ST3 F2, ST4 F1, ST4 F2, ST5 F1 and ST10 F7. All isolates were identified as Trichoderma spp. which could produce phosphatase enzymes. While isolates ST4 F1, ST10 F7, ST4 F2 could produce chitinase enzymes and isolates ST5 F1 and ST3 F2 could produce protease enzymes. Moreover, all isolates of Trichoderma spp. could produce IAA hormones. and isolates ST5 F1, ST3 F2 and ST4 F2 could produce siderophore. Five isolates of Trichoderma spp. were tested for plant growth-promoting ability in tomato plant under greenhouse condition. It was found that Trichoderma sp. isolates ST4 F2 had high potential in stem diameter, canopy diameter, number of fruits, weight of each fruit, fresh and dry weight of shoot and fresh weight of root. Whereas shoot length and leaf greenness were no statistically different when compared to control but tends to be higher. Based on the test results, it was found that Trichoderma sp. Isolates ST4 F2 had plant growth promoting potential and could reduce the severity of the disease. Therefore, Trichoderma sp. Isolates ST4 F2 can be used as an alternative *way to reduce the amount of chemicals used and for the development of sustainable agricultural production in the future.