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 หัวเรื่อง:ปัจจัยที่มีผลกระทบต่อการงอกของเมล็ดหญ้าโขย่ง ผู้เขียน: Reawat Jantawinyurag, รังสิต สุวรรณเขตนิคม สื่อสิ่งพิมพ์:pdf AbstractThe factors influencing seed germination of itchgrass, i,e. days after harvesting, seed coat (hull), GA, KNO3, osmotic potential, soil depth, and light intensity were examined. It was found that newly harvested seeds were dormancy. The dormancy was caused by physiological characteristics inside the seeds and seed coat. The period of physiological dormancy was 11 months after harvesting. However, the period of seed coat dormancy might by longer than 2 years after harvesting. GA at 25, 50 and 100 ppm could break dormancy of itchgrass seeds but not KNO3. Seed kept at room temperature for 2 years could be well germinated at the osmotic potential of 0 to -2 bar. They could emerge when buried up to 20 cm, however most of them can germinate at 2 to 8 cm depth. Light did not seem to affect the germination of itchgrass seed. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Herbicide Concentration in Runoff and sediment from Experimental plots of Highland Cultivated Areas) ผู้เขียน:รังสิต สุวรรณเขตนิคม, Supranee Impitaksa สื่อสิ่งพิมพ์:pdf AbstractBromacil, 2,4-D, dalapon, DCPA, diuron, linuron and oxadiazon at the rates of 4 kg ai/ha, 4 kg ae/ha, 8 kg ae/ha, 8 kg ai/ha, 4 kg ai/ha, 2 kg ai/ha and 2 kg ai/ha, respectively, were applied to cultivated soil of 8 to 10% and 25 to 28% slopes during the middle of rainy season at Royal Ang Khang Highland Agriculture Research Station, Fang district, Chiang Mai. At 8 to 10% slope the maximum concentration of bromacil, 2,4-D, dalapon, DCPA, diuron, linuron and oxadiazon detected in runoff were 29.1, 38.4, 809.7, 36.4, 110.7, 280.0 and 49.3 ?g/L, respectively. At 25 to 28 % slopes the maximum concentration of bromacil, 2,4-D, dalapon, DCPA, diuron, linuron and oxadiazon detected in runoff were 29.4, 31.3, 763.9, 6.9, 46.8, 65.3 and 10.7 ?g/L, respectively. The maximum concentrations of herbicides in runoff were observed within a few days after application and were drastically reduced which might be attributed to half life or persistence and leaching of herbicides in soil. The average amount of bromacil, 2,4-D, dalapon, DCPA, diuron, linuron and oxadiazon in water phase were 67.4, 56.2, 76.5, 32.1, 37.7, 64.2 and 69.2% of total amount of herbicides detected in both water and soil sediment phases, respectively. The maximum concentration of herbicides detected in runoff water were applied to sandy loam soil and leaves of test plants. No phytotoxicity of herbicides were observed except those of bromacil, linuron and oxadiazon when applied to leaves. Total losses of herbicides from both sloped were less than 2% of applied rates except 2,4-D loss was less than 6%. All herbicides moved vertically to 7.5 to 15.0 cm depth. Except bromacil, the other herbicides moved laterally with runoff to surface of adjacent (non treated area) slope base. The persistences of bromacil, 2,4-D, dalapon, DCPA, diuron, linuron and oxadiazon were 117, 30, 30, 180, 180, 241 and 241 days respectively. |
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. |
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 : 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. |
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