scholarly journals ALLELOPATHIC POTENTIAL OF EXTRACTS AND LEACHATES OF AZADIRACHTA INDICA A. JUSS LEAVES ON GERMINATION AND GROWTH OF ELEUSINE CORACANA (L.) GAERTNER

2015 ◽  
Vol 2 (2) ◽  
pp. 129-132
Author(s):  
Elavazhagan P

Various concentrations (5%, 10%, 15% and 20%) of leaf leachates and leaf extracts prepared from fully senesced fallen and matured leaves of Azadirachta indica A. Juss. and used for the present experiments to determine their allelopathic potential on growth and developmental changes on Eleusine coracana (L.) Gaertner. Leaf leachates and leaf extracts sowed an inhibitory effect on germination percentage, root and shoot growth, and fresh and dry weight of E. coracana seedlings. The leaf extracts had more inhibitory effect at 20%concentration,than that of leaf leachates on morphological parameters of E. coracana

2015 ◽  
Vol 2 (2) ◽  
pp. 114-117
Author(s):  
Anbarasan R ◽  
Prabhakaran J

Various concentrations (5%, 10%, 15% and 20%) of aqueous extracts prepared from two weed species namely Ageratum conyzoides L. and Cleome viscosa L. and used for the present experiments to determine their allelopathic potential on growth and developmental changes on sesame (Sesamum indicum L.). The weed extracts showed an inhibitory effect on germination percentage, root and shoot growth, and fresh and dry weight of sesame seedlings. The extracts of A.conyzoides had more inhibitory effect at 20%concentration,than that of C.viscosa on growth parameters of sesame.


2015 ◽  
Vol 2 (2) ◽  
pp. 118-122
Author(s):  
Kavitha D

Weeds are enemies to the crop plants and have harmful effects on agricultural crops due to several factors such as competition for space, light and nutrients and allelopathy. In the present study,various concentrations (0,5,10,15,20 and 25%) of whole plant aqueous extractsof weeds, Cyperus rotundusL.( Purple nut sedge) and Cynodan dactylon(L.) Pers. (Bermuda grass) were tested for assessing their allelopathic potential on seed germination and seedling growth of some rice (Oryza sativa L.) cultivars i.e.ADT-36,BPT5204 and IR-20 using pot culture experiments. The experimental results revealed that all the concentrations of both the weed extracts had inhibition on germination percentage, seedling length, number of,dry weight and chlorophyll contents of 15 day old seedlings of all the three rice cultivars and the inhibitory effect of the extracts was concentration dependent. However, at 5% of C. rotundus and10% of C. dactylon extracts did notaffect seed germination of IR-20 . Among the rice cultivars,the higher degree of growth inhibition was observed in ADT-36followed by BPT-5204 and IR-20 . The weed C.rotundusexhibited more intense on growth suppression of rice cultivars thanC.dactylon.


2011 ◽  
Vol 29 (4) ◽  
pp. 220-222
Author(s):  
Kathryne J. Jernigan ◽  
Amy N. Wright

Abstract Research was conducted to screen four landscape shrub taxa for tolerance to repeated flooding events. Plants of Fothergilla × intermedia ‘Mt. Airy’ (dwarf witchalder), Ilex verticillata ‘Winter Red’ (winterberry), Clethra alnifolia ‘Ruby Spice’ (summersweet), and Viburnum nudum Brandywine™ (possumhaw) were flooded repeatedly over six weeks for 0 (non-flooded), 3, or 6 days with a draining period of 6 days between each flooding event. The experiment was repeated for a total of two runs. With the exception of F. × intermedia ‘Mt. Airy’, all taxa showed good visual quality and no reduction in root growth in either run, and effects on shoot growth were minimal. Size index of Clethra alnifolia ‘Ruby Spice’ was 27% higher in plants flooded for 0 or 3 days than in plants flooded for 6 days in run 1 only. Shoot dry weight of Ilex verticillata ‘Winter Red’ was actually 11% higher in plants flooded 6 days days than in plants flooded for 0 or 3 days in run 2. Size index of Viburnum nudum Brandywine™ increased with increasing flood length, and plants flooded for 6 days had a 9% higher SI than plants flooded for 0 days in run 1. With the exception of Fothergilla × intermedia L. ‘Mt. Airy’, all taxa appeared tolerant of and even thrived during flooding and would be appropriate shrub selections for a southeastern United States rain garden.


Weed Science ◽  
1970 ◽  
Vol 18 (6) ◽  
pp. 692-696 ◽  
Author(s):  
J. Deli ◽  
G. F. Warren

Root application ofN,N-dimethyl-2,2-diphenylacetamide (diphenamid) caused reduction of root and shoot growth of oats (Avena sativaL., var. Jaycee) seedlings. Shoot application did not affect plant growth, but studies with labeled diphenamid showed that diphenamid will enter also through the shoot. In ivyleaf morningglory (Ipomoea hederaceaL.), a considerable amount of label was translocated from the roots to the shoots, but not in oats seedlings. The difference in tolerance between these two species (oats susceptible, morningglory resistant) may lie in the ability of morningglory to translocate diphenamid out of the roots into the shoots faster than oats. The inhibitory effect of diphenamid was restricted to the site of uptake. Reduction in shoot growth of treated plants was the result of the limited root system and it was not a direct effect of diphenamid. Diphenamid was 10 times as toxic to oats as its metabolites. Oats seedlings inhibited by diphenamid for up to 5 days, and then placed in water recovered from the diphenamid caused inhibition. The resumed root growth appeared to be normal. The amount of uptake of14C-labeled sucrose by excised roots treated with 10−5M diphenamid was equal to that in untreated roots; however, more sugar was incorporated into the untreated roots than the treated roots. It appears that diphenamid is a reversible metabolic inhibitor; it inhibits cell division in the root tip perhaps by limiting utilization of substrates in the cells.


Author(s):  
Kalidas Upadhyaya ◽  
B. Gopichand ◽  
Kalidas Upadhyaya

The allelopathic potential of aqueous leaf extracts of Flemingia semialata Roxb. a leguminous herbs was used to examined its effect on growth and yield of Zea mays L. and Oryza sativa L. at different concentrations in laboratory bioassays. The extracts show both inhibitory and stimulatory effect on the test crops. Significant stimulatory effects were observed in 50 and 75 per cent concentration for root length and 25 per cent for shoot length in maize. Stimulatory effect on the root length of rice were observed at lower concentrations, however inhibitory effect were observed on the shoot length whereby the inhibitory effect increases with increase in the concentration of extracts. The inhibitory effect on biomass yield was observed at lower concentration in maize but inhibitory effect was more pronounced in rice at higher concentrations. Aqueous leaf extract of Flemingia semialata Roxb. performed better in maize than in rice.


Author(s):  
Chisato Sakamoto, Masahiko Suzuki ◽  
Arihiro Iwasaki, Kiyotake Suenaga ◽  
Hisashi Kato- Noguchi

The weedy annual grass Lamium amplexicaule (L.) originated from the Mediterranean region, spreads quickly, and becomes naturalized in areas it invades. It was assumed that volatile phytotoxic substances are one of the invasive characteristics of L. amplexicaule. However, no volatile compound has been found. Therefore, we re-evaluated the allelopathic potential of L. amplexicaule and investigated the phytotoxic substances with allelopathic activity. An extract of L. amplexicaule inhibited the root and shoot growth of Lepidium sativum, Lactuca sativa, Arctium lappa, Lolium multiflorum Lam., Echinochloa crus-galli, and Vulpia myuros, which indicates that the extract has an allelopathic effect. The extract was purified using bioassay-guided chromatographic separations, and a phytotoxic substance with allelopathic activity was isolated and characterized as methyl caffeate. The compound significantly inhibited the root and shoot growth of L. sativum and L. multiflorum. The present results suggest that methyl caffeate may contribute to the allelopathic effect of the L. amplexicaule extracts and consequently, may be partly responsible for the invasive characteristics of the species. 


HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 289-293 ◽  
Author(s):  
Michael J. Adler ◽  
Carlene A. Chase

The phytotoxicity of aqueous foliar extracts and ground dried residues of sunn hemp (Crotalaria juncea L.), cowpea [Vigna unguiculata (L.) Walp. cv. Iron Clay], and velvetbean [Mucuna deeringiana (Bort) Merr.] to crop and weed germination and growth was evaluated to compare the allelopathic potential of the cover crops. By 14 days after treatment (DAT), goosegrass [Eleusine indica (L.) Gaertn.] germination with 5% aqueous extracts of all cover crops (w/v fresh weight basis) was similar and greater than 75% of control. However, with the 10% extracts, goosegrass germination was lowest with cowpea extract, intermediate with velvetbean extract, and highest with sunn hemp extract. Livid amaranth (Amaranthus lividus L.) germination declined to ≈50% with cowpea and sunn hemp extracts and even lower to 22% with velvetbean extract. The suppression of livid amaranth germination was greater with the 10% extracts than the 5% extracts. Bell pepper (Capsicum annuum L.) germination was unaffected by velvetbean extract, inhibited more by the 5% cowpea extract than the 10% extract, and was also sensitive to the 10% sunn hemp extract. All cover crop extracts resulted in an initial delay in tomato (Lycopersicon esculentum Mill.) germination, but by 14 DAT, inhibition of germination was apparent only with cowpea extract. The phytotoxicity of ground dried residues of the three cover crops on germination, plant height, and dry weight of goosegrass, smooth amaranth (A. hybridus L.), bell pepper, and tomato was evaluated in greenhouse studies. Goosegrass germination was inhibited in a similar manner by residues of the three cover crops to 80% or less of control. Smooth amaranth germination, plant height, and dry biomass were more sensitive to sunn hemp residues than to cowpea and velvetbean residues. Bell pepper germination, plant height, and dry weight were greater than 90% of control except for dry weight with cowpea residue, which was only 78% of control. The greatest effect of cover crop residue on tomato occurred with dry weight, because dry weights with cowpea and sunn hemp were only 76% and 69% of control, respectively, and lower than with velvetbean. There was more evidence of cover crop phytotoxicity with the weed species than with the crop species and cowpea extracts and residue affected all species more consistently than those of sunn hemp and velvetbean.


2016 ◽  
Vol 34 (4) ◽  
pp. 639-648 ◽  
Author(s):  
A.P.P. OLIVEIRA ◽  
S.R. PEREIRA ◽  
A.C.S. CÂNDIDO ◽  
V.A. LAURA ◽  
M.T.L.P. PERES

ABSTRACT Tree establishment in pasture areas can be inhibited, at least in part, by exotic grasses allelopathy and this can represent an important limitation by changing the patterns of both germination and seedling growth of tree species. This study aims to evaluate the allelopathic potential of Urochloa brizantha and U. decumbens on germination, growth and metabolism of Guazuma ulmifolia seedlings. We performed bioassays evaluating the effect of the crude ethanol extract and semipurified fractions (hexane fraction, ethyl acetate fraction and ethanol-water fraction) of U. brizantha and U. decumbens using completely randomized design, with four concentrations (0, 250, 500, 1,000 mg L-1) and four replications. The variables analyzed were germination percentage, mean germination time, shoot and root growth, catalase and peroxidase activity, chlorophyll content and root respiration. The results showed that both grasses have an inhibitory effect on G. ulmifolia metabolism, affecting both germination and seedlings growth and inducting metabolic defense. Thus, these results show that the grass species evaluated have the potential to restrict the re-introduction of G. ulmifolia in pasture areas due to interference competition.


2021 ◽  
Vol 27 (2) ◽  
pp. 191-200
Author(s):  
Iqtidar Hussain

A biological phenomenon by which one plant releases some chemicals in the environment that affect the rate of germination, its seedling emergence and physiology and overall growth of neighboring plants is called allelopathy. The significance of study was checked allelopathic phytochemical potential of Daraikh (Melia Azedarach L.) leaves on Wheat. Leaves litter were used to examine the allelopathic effects of Daraikh (Melia Azedarach) at five concentrations (100, 200, 300, 400 g, control) parameters studied germination percentage (%), Speed of germination, plant height (cm), root length (cm), Shoot length (cm), coleoptile length (cm), Fresh weight (g) and dry weight (g), Tiller (plant-1) and chlorophyll content (µ cm-2) of Triticum aestivum. All concentration of Leaves litter of Melia Azedarach showed pronounced inhibitory effect on all parameters of Triticum aestivum. Melia Azedarach exerted phytotoxic influence on Triticum aestivum at initial growth stages. Melia Azedarach exhibited a significant negative impact on germination of Triticum aestivum at 100, 200, 300, 400 g litter of leaves than control (Sterilized soil) repectively. Melia Azedarach halted the coleoptile length of Triticum aestivum @ 400 g leaves litter. Powdered leaves of Melia Azedarach in clay loam soil appeared to have strong allelopathic inhibition under maximum concentrations on growth and germination of Triticum aestivum. Hence, Melia Azedarach proved a strong allelopathic plant that should be planted aside from field to avoid harmful impacts during early growth stages of Triticum aestivum.


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