• Weed & Turfgrass Science
• /
• v.6 no.1
• /
• pp.61-66
• /
• 2017

The appropriate level of irrigation for turfgrasses is vital to the performance of the turfgrass as well as conservation of water. Linear gradient irrigation system (LGIS) facilitates long-term study of turf performance under continuous irrigation gradients at extreme ends of the irrigation scale. The objectives of this study were to: a) determine the minimum irrigation requirements and relative drought resistance in three warm season turfgrasses; and b) evaluate the medium to long-term effects of irrigation levels on turf persistence, weed invasion, and susceptibility to diseases. Results suggest that grasses differed in drought resistance and persistence under variable irrigation regimes. Irrigation (Ep) required for consistent acceptable turf quality for respective grasses was Cynodon dactylon x C. transvaalensis (61%), Zoysia matrella L. Merr (73%), and Stenotaphrum secundatum 'Palmetto' (86%). Brown patch infection was most prevalent in Stenotaphrum secundatum 'Palmetto' at 12 and 125% Ep irrigation. Cynodon dactylon x C. transvaalensis and Zoysia matrella L. Merr were better able to adapt to the various irrigation regimes, and this ability allowed these species to resist drought, and maintain turf coverage which in turn, kept weeds and the occurrence of diseases at bay. Ranking these grasses for their drought tolerance abilities showed that Cynodon dactylon x C. transvaalensis had the most outstanding resistance against drought, followed by Zoysia matrella L. Merr, and lastly, Stenotaphrum secundatum 'Palmetto'. Despite having the highest irrigation requirement, Stenotaphrum secundatum 'Palmetto' was still not able to maintain persistence at high irrigation regimes. Likewise, this grass also lost turf coverage at low irrigation levels.

• Korean Journal of Weed Science
• /
• v.32 no.3
• /
• pp.230-239
• /
• 2012

Coconut (Cocos nucifera L) is one of the predominant plantation crops in Sri Lankan economy which is known to have existed for over thousands of years. During the past decades coconut production had been reduced by a significant quantity. The usage of poor quality planting materials is a major reason for the low coconut production. Thus much attention needs to be paid in coconut nurseries. Weed management is a critical management practice in the nursery. Though glyphosate application is becoming popular in nurseries it can affect weeds as well as coconut seedlings growth. Therefore the effects of glyphosate were evaluated by determining the growth of shoot and root of coconut seedlings. Poly bag nursery was prepared and three treatments were used. Treatments were no glyphosate and manual weeding ($T_1$), application of glyphosate 1.08 ai kg $ha^{-1}$ at 2 monthly interval ($T_2$) and application of glyphosate 1.44 ai kg $ha^{-1}$ at 2 monthly interval ($T_3$). Application of glyphosate at early stage of seedling growth had a no significant effect on growth parameters tested. However, the concentrations of glyphosate negatively affected numbers, volumes and dry weights of secondary, tertiary and quaternary roots at the latter stage of seedling growth. The leaf area and the height of seedling were significantly reduced by the highest concentration of glyphosate. Among the growth parameters tested, seedling girth and shoot dry weight were not affected by the application of glyphosate. These results revealed that the usage of glyphosate at both concentrations negatively affected root growth of coconut seedlings. Based on these results, the both concentration levels of glyphosate should be applied to coconut nurseries before sprouting the seed nuts.

• Korean Journal of Weed Science
• /
• v.10 no.4
• /
• pp.305-311
• /
• 1990

Effects of light on germination of major weeds in upland fields were examined. Most weeds showed light positive response to germination at above 25$^{\circ}C$, but germination percentage was very low at lower temperatures. Red light promoted germination of Amaranthus lividus, Portulaca oleracea, and A. retroflexus, but far-red light inhibited germination. Germination resposnse of A. retroflexus, A. lividus, and P. oleracea showed reversible reaction to red/far-red light, and thus it seemed that phytochrome was involoved in seed germination, Echinochloa crusgali and Eleusine indica showed higher germination percentage under the conditions of continuous illumination of red, white, and bule lights, and thus it was estimated that blue light pigment (HIR, high irradiation reaction) related to long time illumination was involved in germination in addition to phytochrome.

• Korean Journal of Weed Science
• /
• v.9 no.1
• /
• pp.69-75
• /
• 1989

To search germination inhibitors in higher plants, first of all, some experiments containing selection of test weed seeds and effects of solvents and surfactants for bioassay establishment were conducted. Then MeOH-extracts of 45 plants were assayed for germination inhibition activities against Echinochloa crus-galli (L.) Beauv, Digitaria sanguinalis (L.) Scop., Cyperus iria L., Portulaca oleracea L. and Oenothera lamarckiana Ser. seeds. Among them extracts from Rhathiolepis ovata Briat and Picea abies (L.) Karst showed strong inhibitory effect (60-90% inhibition) on the germination of tested weed seeds at 5000 ppm. On the other hand, the extract from Youngia sonchifolia Max stimulated the germination and growth of tested weeds.

• Korean Journal of Weed Science
• /
• v.16 no.4
• /
• pp.346-353
• /
• 1996

To study the effects of metal ions on the activities of antioxidative enzymes, the activities of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) of Persicaria vulgaris has been studied after treating with Cd, Cu, Zn and Al. 1. The activities of SOD in leaf and stem were decreased, but that in root was increased. Among the metal ions studied in this report, Al gave the highest increase in SOD activity in root. 2. The activities of POD after treating with Cd or Cu did not show any significant differences. POD activities after treating with Zn and Al has been decreased, however, that in root showed increased activities after treating with Zn 5,000 ppm or Al 500 ppm. 3. The activity of CAT in leaf was decreased with every metals studied. The CAT activity in root was increased with increased concentration. The root treated with Al showed highest activity. 4. The presence of isozymes after treated metal ions has been studied in gel electrophoresis. The POD treated plant did not show any new isozymes, but the intensity of one of pre-existent band was increased. The SOD treated plant showed the several new isozymes.

• Korean Journal of Weed Science
• /
• v.30 no.3
• /
• pp.199-205
• /
• 2010

This study was conducted to investigate the phytotoxic effects of 19 essential oils on seed germination and initial growth of rapeseed (Brassica napus L.). We found that anise, cinnamon, citronella, clove, geranium, lemongrass, mustard and pine oils completely inhibited germination of rapeseed at $100{\times}$ dilute solution. Based on the inhibition rates of rapeseed emergence and initial growth, three essential oils (cinnamon, clove, and geranium) were selected as potential bio-herbicides. Under pre-emergence applications of cinnamon, clove, and geranium oils at 90 kg ai $ha^{-1}$, rates of rapeseed emergence were 7.1, 25.0, and 3.6% and its initial growth were 22.0, 9.9 and 11.0%, respectively.

• Korean Journal of Weed Science
• /
• v.14 no.1
• /
• pp.1-7
• /
• 1994

The effects of S-23142{N-(4-chloro-2-fluoro-5-propargyloxyphenyl)-3, 4, 5, 6-tetrahydrophtalimide}, on protoporphyrin IX(PPIX) biosynthesis in Spinacia oleracea L, leaf in vivo and in vitro condition were investigated by reversed-phase HPLC with fluorescence detector. The stroma and the membrane fraction of spinach chloroplast were isolated by osmotic regulation. The conversion of ${\delta}$-aminolevulinic acid(ALA) to PPIX occured more in the stroma than in the membrane fraction. It suggested that the enzymes that catalyse PPIX biosynthesis from ALA were localized in the stroma. Also, the synthesized PPIX content from ALA was completely inhibited by $10^{-8}M$ of S-23412 or $10^{-7}M$ of acifluorfen in the stroma but not in the membrane fractions. Therefore, these results suggested that the target site of S-23142 and acifluorfen may exist in the stroma fraction of spinach chloroplast.

• Korean Journal of Weed Science
• /
• v.15 no.1
• /
• pp.1-12
• /
• 1995

These researches have been conducted to obtain the basic information of the effects of paraquat on plant species and to screen the plant species showing specific responses to paraquat. Paraquat resistance related to ecotype and overwintering capacity. Perennial and biennial species showed higher resistance than annual species. In a family, most species showed higher resistance were overwintering species. Lamiaceae, Brassicaceae, and Caryophyllaceae were tolerant to paraquat, whereas Poaceae and Asteraceae were sensitive. Especially Mosla dianthera of Lamiaceae, Hemistepta lyrata and Aster pilosus of Asteraceae, and Paspalum thunbergii of Poaceae showed higher tolerance than others. The response patterns of plant species on germination stage were different to those on vegetative stage. Germination of Amarathus lividus, Arabis glabra, and Bidens frondosa was not inhibited by paraquat. But their seedling growth were highly inhibited.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.4
• /
• pp.459-469
• /
• 2009

It is well known that coagulation pretreatment can reduce foulants prior to membrane filtration. The purpose of this research was to investigate the effects of coagulation on fouling of ceramic microfiltration membrane($0.1 {\mu}m$) using pilot plant of $150m^3/day/train$ capacity. Train A membrane system has pretreatment process of ozonation and coagulation while train B has only coagulation. Two types of coagulation operation were investigated: back mixer(rapid mixing with or without slow mixing) which is a conventional mechanically stirred mixer and an inline static mixer. Ozone dose rate for train A was 1 mg/L and ozone contact time was 12 min. The coagulation dose(PACl 10% as $Al_2O_3$) rate was changed 20~40 mg/L according to experimental schedule. In this experimental conditions, the coagulation of back mixer type with rapid mixing(GT=72,000) and slow mixing(GT=45,000) was the best effective in reduction of ceramic membrane fouling regardless preozonation. Especially, the effect of inline static mixer was sensitive to change in water quality. Ozonation mainly affected irreversible fouling rather than reversible fouling in accordance with less adsorption of NOM on the membrane surface. Thus, the increase rate of the nomalized TMP(trans membrane pressure) at $25^{\circ}C$ for train A was relatively lower than that of train B under same coagulation process with same coagulant dosage. The best performance of ceramic membrane appeared in case of combined process with ozonation, therefore this integrated process is able to archive less coagulant dosing and secure a stability of ceramic membrane system.

• Korean Journal of Weed Science
• /
• v.11 no.2
• /
• pp.122-127
• /
• 1991

The allelopathic effects of rice and barley straws on lettuce germination and weed growth were investigated. The grinded straw of rice significantly inhibited lettuce germination. Both rice and barley straws decreased weed growth when they were used as a mulch in the field. Rice straw mulch applied with 500g/$m^2$ and 700g/$m^2$ decreased dry weight of Alopecurus aequalis more than 35%. Barley straw mulch applied with 200 g/$m^2$ inhibited dry weight of Echinochloa curs-galli and Digitaris sanguinalis, while the straw applied with 300 g/$m^2$ decreased those by 97%.