 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Hard Seededness and Germination of Small White Flower Morningglory) ผู้เขียน: รังสิต สุวรรณเขตนิคม,  นายอนุชา จุลกะเสวี, ผู้ช่วยศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractSmall white flower morningglory (Ipomoea obscura (L.) Ker-Gawl) has hard seeds. Scarification in 97.7% sulphuric acid for 40 to 120 minutes allowed germination, and the 80 minute treatment produced the fastest germination rate (recorded as coefficient of velocity). For acid scarified seeds germination did not differ at pHs ranging from 2.2 to 8.5, but the coefficient of velocity was greatest at a pH of 7.0, while germination decreased as osmotic potential increased from -0.19 to -0.76 MPa, and no germination occurred at -0.79 MPa. Cold scarification at 4?C did not allow germination of non-scarified seeds and had no effect on the germination of scarified seeds, which germinated equally well (>90%) at constant temperatures between 15 and 35?C. Germination at alternating temperatures did not differ from that at constant temperatures. Seeds on the soil surface did not germinate, but >85% emergence was recorded at sowing depths of 1 and 2 cm. Seeds sown at 8 and 12 cm did not emerge. Reducing light intensity (from 100 to 25% of full sunlight) did not affect seedling emergence or plant dry weight 12 weeks after sowing, but did delay the time to flowering. As this climbing weed can smother pineapple fields, it is important that effective control is achieved at the seedling stage. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Effects of Certain Additives on Activity of Some Postemergence Herbicides in Relation with Carrier Volume) ผู้เขียน:รังสิต สุวรรณเขตนิคม สื่อสิ่งพิมพ์:pdf AbstractField experiments were conducted to determine the effect of OPPEE (octyl phenoxy poly ethoxyethanol), AAPE + SASA (alkyl aryl polyethoxylate + sodium salt of alkylsulfonate alkylate), thalestol, and TAE (tallow amine ethoxylate) at various concentrations to increase activity of glyphosate, glufosinate, and impzapyr or Imperata cylindrica L. and the effect of the same additive to increase activity of glyphosate on Cyperus rotundus L. and Cynodon plectostachyous (L.) Pers. Herbicides in combination with additives were applied at low carrier volume (14.4-48.7 1/ha) and at high carrier volume (138.2-265.0 1/ha). It was found that various additives alone did not increase activity of ghyphosate , glufosinate, and imazapyr on I. cylindrica and C. plectostachyous. But OPPEE at 0.12, 0.25 and 0.5% (v/v), thalestol at 0.25 and 0.5% (v/v), And TAE at 0.25, 0.5 and 1.0% (v/v) increased activity of glyphosate 0.63 kg ai/ha when it was applied at 14.4 l/ha on C. rotundus. OPPEE, AAPE + SASA, and thalestol at 0.25% (v/v), and TAE at 0.05% (v/v) also increased activity of glyphosate at 1.8 or 1.4 kg ai/ha on C. rotundus at the carrier volume of 38.1 and 128.2 l/ha. Phytotoxicity of glyphosate on I. cylindrica, C. rotundus , and C. plectostachyous increased when carrier volume was reduced. However, phytotoxicity of glufosinate and imazapyr on I. cylindrica decreased when carrier volume was reduced. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Degradation and Residues of Dimefuron in Pineapple) ผู้เขียน:รังสิต สุวรรณเขตนิคม, Walaiporn Sasiprapa สื่อสิ่งพิมพ์:pdf AbstractDimefuron-14C (1,1-dimethyl-3-(3-chloro-4-(2-t-butyl-5-oxo-1,3,4-oxadiazolin-4-yl) phenylurea) was applied to Smooth Cayenne pineapple plants (grown from tillers and crowns), at the rate of approximately 2.5 kg ai/ha, at 3 days, 4 and 9 months after planting. Plants were harvested after 16 months and the 14C-residues were analysed by extraction with acetone, methanol and 0.1 N. HCl/90% methanol respectively. The extracts and bound residues were assayed by liquid scintillation counting and a combustion technique respectively. The results showed that dimefuron and/or its metabolites were absorbed via the roots and /or shoots and transported to the fruits, which developed after application. At harvest the radioisotope was found in all parts of the treated plants. The 14C-residues expressed as dimefuron equivalents in flesh, peel, crown, stem and leaves were 0.045, 0.049, 0.087, 0.288 and 0.822 ? g/g (fresh weight) for the pineapples grown from crowns and 0.064, 0.058, 0.0128, 0.405 and 1.235 ? g/g (fresh weight) for the pineapples grown from tillers respectively. In the pineapple flesh 81.3 to 97.8% of the residue was found in acetone and methanol, 0.0 to 12.5% in 0.1 N. HCl/90% methanol and 2.2 to 6.3% as a bound residue. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Screening of Tomato (Lycopersicon esculentum Mill.) Varieties for Resistance to Branched Broomrape (Orobanche ramosa L.)) ผู้เขียน:Etagegnehu G. Mariam, รังสิต สุวรรณเขตนิคม สื่อสิ่งพิมพ์:pdf AbstractThirty tomato varieties were evaluated for branched broomrape resistance in pot experiments under natural conditions in Central Rift Valley of Ethiopia. The susceptible variety of tomato Roma VFN was used as a control. Percent yield loss of tomato due to branched broomrape was used as a main parameter and number and dry weight of branched broomrape shoot per tomato plant, were used as support parameters. Results revealed that the highest levels of resistance were found in varieties, LE 244, LE 180 A, South Africa, CLN 2123 A, Florida MHI UCG, Riogrande, Melekashola and Seedathip, with yield losses of 32% to 43% and numbers of parasite per plant were 7.0 to 13.0. Caribe and Floradade varieties were found to be highly susceptible to branched broomrape with yield losses 74% and 75% respectively. Thirty one and thirty three branched broomrape shoots developed on their roots. The percent yield loss (37%) of South Africa variety seemed minimal compared to the varieties parasitized by lower and equal number of branched broomrape. This indicated that South Africa variety was less affected by the parasite. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Loss of Amide Herbicides in Runoff Water and Sediment and Their Persistence in Soil) ผู้เขียน:รังสิต สุวรรณเขตนิคม, Montri Toopornsiri สื่อสิ่งพิมพ์:pdf AbstractAlachlor and butachlor at the rate of 4.0 kg ai/ha metolachlor at the rate of 3 kg ai/ha, and propanil at the rate of 6 kg ai/ha were applied to the cultivated soil of 8-10 and 25-28% slopes during the middle of rainy season at Royal Angkhang Highland Agriculture Research Station, Fang district, Chiangmai. The soils of the 8-10 and 25-28% slopes were clayloam and clay, respectively. At the 8-10% slope site the maximum concentrations of alachlor, butachlor, metolachlor, and propanil in the runoff were 46.1, 61.5, 65.0 and 86.3 ug.L respectively. At the 25-28% slope site the maximum concentration of alachlor, butachlor, metolachlor, and propanil in the runoff were 18.5, 15.5, 51.4 and 70.3 ug/L, respectively. The highest amounts of water, soil, and herbicides were lost from both sites 1 to 3 days after application. The average amount of alachlor, butachlor, metolachlor, and propanil in the water phase were 66.4, 52.2, 68.0 and 54.9% of the total amount of herbicides found in the combined sediment and water phases, respectively. The maximum concentrations of herbicide were applied to leaves and to sandy loam soil where test plants were grown under greenhouse condition. Plant dry weight were reduced significantly by all herbicides when foliar application was practiced. The plant dry weight were not affect by soil application of herbicides. This indicating that all the chemicals were adsorbed by clay particle and organic matter. Total losses of all herbicides were less than 0.5% of the applied rates. The downward movement of the herbicides to the depth of 7.5-15 cm. was as follows: metolachlor > propanil > alachlor > butachlor which was in correlation with their water solubility. The persistence of alachlor, butachlor, metoachlor, and propanil in the soil of the treated area which could be detected by gas chromatography were 180, 180, 117, and 30 days after application, respectively. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Efficacy of s-Triazines as Influeced by Adsorbtion and Mobility of Various Soils ) ผู้เขียน:รังสิต สุวรรณเขตนิคม, Ronnayoot Sattayanikom สื่อสิ่งพิมพ์:pdf AbstractField experiments were conducted on Kampang Saen clay, Kampang Saen silty loam and Nampong sand in 1987 and 1988 to study the efficacy of atrazine, ametryn, dimethametryn and simazine and the influence of various soil parameters on s-triazine efficacy. The average rates of all herbicides were required to produce 80% weed control at 8 weeks after application were in the order simazine > dimethametryn > atrazine =ametryn. The average rates of all herbicides were requited to produce 80% weed control across herbicides were in the order Kampang Saen clay > Kampang Saen silty loam > Nampong sand. The efficacy of herbicides were correlated with CEC values but negatively correlated with % sand contents. These results indicated that soil with high CEC value required high rate of s-atrazines. But soil with high sand content required low rate of herbicides. Laboratory experiments indicated that adsorption of herbicides were in the order dimethamethyn > simazine> atrazine = ametryn. While adsorption of dimethametryn and simazine were correlated with CEC values. The adsorption for atrazine and ametryn were correlated with % clay, % organic matter content, and CEC values respectively but negatively correlated with % sand content. Rf values indicated that mobility of herbicides were in the order atrazine > simazine > ametryn > dimethametryn. Furthermore the movement of herbicides were correlated with % sand content but negatively correlated with all soil parameters. The herbicide efficacy, adsorption, and mobility did not get into the same order suggested that efficacy of herbicides could not only be attributed to differences in soil adsorption and mobility but also molecular toxicity and environmental factors. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Influence of Ammonium Sulfate, Diesel Oil, and Surfactant on Glyphosate Activity in Purple Nutsedge) ผู้เขียน:รังสิต สุวรรณเขตนิคม สื่อสิ่งพิมพ์:pdf AbstractEffects of additives on 14C-glyphosate penetration into purple nutsedge leaves and efficacy of glyphosate for purple nutsedge control were examined in 2 weeks old plants. It was found that the addition of (NH4)2SO4 at 1.0 % (v/v) + diesel oil at 1.0 % (v/v) + Tendal at 1.0 % (v/v) increased 14C-glyphosate penetration into nutsedge leaves more than the addition of either one. (NH4)2SO4 at 1.0 % + diesel oil at 1.0 % + Tendal at 0.12 or 0.25 % increased phytotoxicity of glyphosate at 0.5 and 0.75 kg ae/ha on the weed, in the greenhouse. Additives did not enhance glyphosate activity by reducing number of nutsedge tubers. |
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