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The hypothesis of this research is guava planting material produced on the area in central plain of Thailand have root-knot nematodes at high degree. For 1200 samples from all of important commercial nursery of Nakornpathom province were randomly detected for root-knot nematodes. The results revealed that the nematodes were detected in every nursery in which the samples percentage, 30 percents, showed root-knot symptom. Sixty percents had no symptom but the nematodes were detected by higher sensitivity technique, TRAP PLANT METHOD (TPM).
The experiment on controlling root-knot nematodes by antagonistic fungi, Pleurotus ostreatus, was to investigate the efficacy against root-knot disease in guava planting material. The results showed that the inhibition percentage of root-knot disease was 80 percents in spent mushroom, P. ostreatus , treatment and 55 percents in P. ostreatus concentrated filtrate (2N) treatment. The mechanisn of action of P. ostreatus was studied that the nematotoxin , ostreatin, from mycelium paralyzed the nematodes mobility. The juveniles were immobilized and dead or P. ostreatus infect through the body and ingest inner liquid body as their food.
We conducted field surveys for studying weed tolerance to infestation of Meloidgyne spp. in 23 guava orchards in Nakhon Pathom and Samut Sakorn provinces in Thailand. We classified nematode-tolerant weeds into viz., (1) highly resistance (Alternanthera sessilis, Ruellia tuberose, Ludwigia hyssopifola, Trianthema portulacastrum, Sida acuta and Digitaria ciliaris), (2) resistance group (no plants in this group), (3) moderately resistance (Abutilon hirtum, Euphobia hirta and Echinochloa colana), (4) moderately susceptible (Hyptis suaveolens, Eclipta prostrateI, Ipomoea aquatic and Hedyotis corymbosa), (5) susceptible group (no plants in this group), and (6) host susceptible group (Physalis minima, Euphorbia geniculata and Vernomia cinerea). Resistance evaluation based on number of nematode in root zone, percentage of root-knot, and fecundity under greenhouse condition revealed that Crotalaria juncea, Digitaria ciliaris and Eleusine indica survival of Meloidgyne spp and that Abutilon hirtum and Echinochloa colana were the best host for nematode. Additionally, the efficacy of the extracts from some plant and weeds on second stage juveniles (J2) of Meloidogyne spp. were determined. The nematicidal activity of hexane and ethanol plant extracts at the concentration of 1,000 ppm against root-knot nematode in vitro was evaluated at 8, 24 and 48 hours. The results showed that ethanol extracts of Hyptis suaveolens leaves, Abutilon hirtum leaves and whole-plant of Euphobia hirta were effective against nematode. Various concentration, 100, 200, 500, 1,000 and 2,000 ppm, of these crude effective extracts were tested for inhibitory activity. The root-knot nematode mortality rate increased with concentration of the extracts and the test period. Nematicidal tests revealed that the leaves extract of Abutilon hirtum was the most effective against meloidogyne spp. J2s with 43.05%, 62.73% and 75.74 % mortality, respectively, at 500, 1,000 and 2,000 ppm after 48 hours of exposure. The efficacy of the essential oil from Hyptis suaveolens on second stage juveniles (J2) of Meloidogyne spp. was also study. The nematicidal activity was evaluated at 4, 6, 8, 24 and 48 hours and the essential oil from Hyptis suaveolens which consist of monoterpene with 1,8-Cineole and ?-Pinene as main constituents was inactive against nematodes. In the present study, ethanol extracts of Euphobia hirta at the concentration of 1,000 and 2,000 ppm has shown a significant suppression of root-knot numbers and fecundity of nematode in tomato roots under greenhouse conditions. The inhibitory activity on root-knot numbers and fecundity of nematode in guava seedling roots need further study that used susceptible guava seedling for investigation because the nematode tolerance guava seedling used in this study contain the low number of root-knot and fecundity of nematode. In this research, the effects of optimal conditions on the production of bioactive compounds from king bolete mushroom mycelia were studied. The results showed that the shaken-flask and non shaken-flask cultures had no effect on mycelial growth and metabolite production. The optimal nitrogen sources and pH for bioactive compound production were peptone, yeast extract, and pH 8. From thin layer chromatography (TLC) analysis of crude extract, it was found that the extracts from different culture conditions tended to produce same bioactive compounds. Moreover, phytochemical screening indicated that the chemical constituents in the extracts were saponin, phenolic compound, and tannin. The total phenolic compound was 966.3 mg/liter. The crude extracts were separated by chromatographic methods such as column chromatography, solid phase extraction, preparative TLC and HPLC, and the active fraction was further indentified by spectroscopic methods. The results showed that it was cumarin derivatives.
Efficacy of the filtrate from king bolete mushroom mycelia in controlling root-knot nematode of quava ‘Pansithong’ in the greenhouse was studied. The results showed that every concentration of the filtrate tended to significantly reduce root galls and egg mass of 45 days guava seedlings after inoculating with 2nd stage of root-knot nematode isolate Kamphaeng Saen, and applying the filtrate. The increased application of this filtrate tended to reduce root galls and egg mass, except at the concentration of 90%. Moreover, the numbers of this filtrate application had no effect on controlling root-knot disease of those guava seedlings. The average of root galls and egg mass of root-knot nematodes isolate Phetchaburi was not significantly different, but the application of this filtrate more than 8 times tended to reduce the average of root galls. In addition, the filtrate from the bolete mushroom and oyster mushroom isolate PO3 mycelia could decrease the root galls of root-knot nematode isolate Phetchaburi about 24.36% and 14.99%, respectively, compared to the control.
The efficiency of bolete mycelia filtrate and bolete spawn for controlling root-knot nematode of guava ‘Pansithong’ air-layerings in the field was studied. The results showed that every concentration of the filtrate from bolete mycelia (30 60 and 90%), and the application of bolete mushroom spawn and oyster mushroom spawn isolate PO3 had no effect on controlling root-knot nematode isolate Phetchaburi of those air-layerings, with disease level 5, and the gall number was more than 75%.
The most serious problem for the guava production in Thailand is the root-knot nematode (Meloidogyne incognita). Tolerant rootstock is the most efficient practice to prevent infection. The objectives were to detemine the mode of gene action and inheritance of root-knot nematode tolerant trait in guava. Four root-knot nematode tolerant varieties: "XaLi", HORT-R1, "Taiwan" and "India" and four susceptible varieties: "Alla Habad Safeda", "Thai", "Klom Salee" and "Beaumont" were used in a diallele cross. Thirty six crosses resulted from selfing and crossing were generated. Seedlings were raised in 6-inch sized plot for 11 months, then were inoculated with 400 J2 of "Nakhon Pathom" and "Phetchaburi" isolate. The experiment was a comletely randomized design. After 60 days, a number of gall and egg mass in root system was recorded as root-knot traits. The data was analyzed using the Method II model I by Griffing and narrow-sense heritability was estimated using the mid-parent and offspring regression analysis. The results showed that root-knot traits had continuous variation indicating their quantitative nature. The general combining ability (GCA) played much greater role than that of specifie combining ability (SCA) where the ratio of GCA to SCA is 3.9 : 1 for gall and 4 : 1 for egg. The heritability was moderate for gall (h2 = 0.63) and was high for egg (h2 = 0.84). The resulted indicated that the promising parents for further breeding was HORT-R1 and "XaLi" because they showed lowest number of gall and egg mass. In addition, they possess highest GCA. Five different propagation methods (chip budding, inarching, cleft, side veneer, and bark grafting) were compared. The results indicated that inarching method had the highest success rate (100%) followed by side veneer and bark grafting with 20% success rate. The chip budding and cleft grafting method had 0% success rate. All 5 nematode tolerant rootstocks (‘HORT-R1’ ‘India’ ‘Taiwan’ ‘Tonte Klom’ and ‘Thai 1’) had no negative effects on growth, productivity and fruit quality of 3 dessert-type cultivars (‘Paen Seethong’, ‘Kimjoo’ and ‘Daeng AngKhang’). Keeping guava seeds at 5 C until 24 months had no effects on germination and seedling vigor. The results indicated that using the 5 rootstocks for multiply the 3 cultivars for commercial production is practical. |