BIOLOGICAL ACTIVITY OF SUBTERRANEAN RESIDUES OF CYNODON DACTYLON L., SORGHUM HALEPENSE L. AND CYPERUS ROTUNDUS L.*

Abstract

Dried subterranean organs of Cynodon dactylon, Cyperus rotundus and Sorghum halepense were incubated in light and heavy soils for 1, 2 or 3 months. After removal of the decayed plant material, the residual bioactivity ofthe soil was assayed by barley sown directly into the soil and by a barley radicle-length test on an ethanolic extract of the soil. The two assays gave similar results. In general, the inhibition of growth was proportional to the concentration of plant material in the soil, and was greater in light than in heavy soil. Greater inhibition was caused by C. rotundus and S. halepense than by C. dactylon. A few instances of growth stimulation were recorded. Activity biologique de residus souterrains de Cynodon dactylon L., de Sorghum halepense L. et de Cyperus rotundus Z... R^sum^. Des organes souterrains d&s^ch6s de Cynodon dactylon, Cyperus rotundus et Sorghum halepense ont €l6 enfouis dans des sols 16gers et dans des sols lourds pendant 1, 2 ou 3 mois. Apr6s avoir enlev6 le materiel v6g6tal d^compos^, l'activit^ biologique r&iduelle du sol a 6t6 6valu6e avec de I'orge sem^e directement dans le sol et par un test portant sur la longueur de la radicule de I'orge dans un extrait ^thanolique dusol. Eng^n^ral, l'inhibition de la croissance fut proportionnelle i la concentration du materiel vdg^tal dans le sol, et fut plus grande en sol 16ger qu'en sol lourd. L'inhibition provoquee fut plus importante avec C. rotundus et S. halepense qu'avec C. dactylon. Quelques cas de stimulation de croissance furent enregistrfe. Die biologische Aktivitat unterirdischer Teile von Cynodon dactylon L., Sorghum halepense L. und Cyperus rotundus L. Zusammenfassung. Getrocknete unterirdische Organe von Cynodon dactylon, Cyperus rotundus und Sorghum halepense wurden in leichten und schweren Boden uber ein, zwei und drei Monate inkubiert. Danach wurde das verrottete Pflanzenmaterial entfernt und die verbliebene biologische Aktivitat des Bodens mit direkt in den Boden gesater Gerste und mit Hilfe von athanolischem Bodenextrakt und einem Gerstenwurzeltest gemessen. Im allgemeinen war die Wuchshemmung proportional der Konzentration des pflanzlichen Materials im Boden und war starker im leichten als im schweren Boden. C rotundus und S. halepense verursachte starkere Wuchshemmung als C. dactylon. Es wird liber einige Falle berichtet in denen das Wachstum stimuliert wurde.

Allelopathic effects of Cyperus rotundus extract in vitro and ex vitro on banana

“…The maximum decrease was recorded at 2% concentration. The aqueous extract of tubers (Singh 1967;Raju and Reddy 1996) or shoots (Ameena and George 2002) or C. rotundus infested soil, infested soil extract and soil incorporated tubers Horowitz and Friedman 1971) were found to inhibit germination and seedling growth (radicle and plumule length, and dry weight), shoot length and dry matter of the crops. The allelochemicals also affected the photosynthesis due to reduction of chlorophyll content and photosynthetic area (Eyini et al 1989;Bajaj et al 2004) or chlorophyll and protein contents (Thapar and Singh 2005).…”

“…Aqueous extract of its tubers was tested on ten test crops and was found to inhibit the seed germination except maize and cotton and the seedling growth of the test crops (Singh 1967). The nutsedge infested soil, infested soil extract and soil incorporated tubers reduced the seed germination of barley, mustard and cotton and seedling growth of barley, sorghum, soybean, cotton, cucumber and tomato Horowitz and Friedman 1971). The inhibitory effect of extracts of C. rotundus and C. esculentus on germination and seedling growth of rice has been reported (Raju and Reddy 1996).…”

Efectos de extractos acuosos de la maleza Cyperus rotundus L. (Cyperaceae) sobre la germinación de semillas y crecimiento de plántulas de maíz ( Zea mays L.) cv. Pioneer 3031

“…Las relaciones estudiadas (altura de la plántula/longitud de la radícula y peso seco del vástago/pesos seco de la radícula) tuvieron una tendencia similar a los caracteres individuales. Resultados similares han sido indicados por Horowitz y Friedman (1971) quienes afi rman que el sistema radicular de los cultivos se reduce cuando se desarrolla en un medio con un alto contenido de residuos de partes subterráneas de malezas perennes; la secreción de sustancias originadas por estos residuos puede tener efectos ecológicos signifi cativos, si ellas incrementan los daños del cultivo.…”

INFLUENCE OF BACTERIA IN THE PHYLLOSPHERE OF CAMELINA SATIVA (L.) CRANTZ ON GERMINATION OF LINUM USITATISSIMUM L.

“…A number of workers, for example Horowitz and Friedman (1971), have described bioactive factors which stimulate growth at low concentrations but are inhibitory at high concentrations. In the present study it appears that a stimulator of Linum was present in Camelina leaf washings and that its effect remained constant over a wide range of dilutions.…”