scholarly journals Effect of age of a sorghum-sudangrass hybrid on its allelopathic action

2008 ◽  
Vol 26 (4) ◽  
pp. 707-716 ◽  
Author(s):  
G. Marchi ◽  
E.C.S. Marchi ◽  
G. Wang ◽  
M. Mcgiffen

Hybrids of Sorghum sudanensis (sudangrass) and Sorghum bicolor genotypes can produce high amounts of biomass, sorgoleone (a long chain hydroquinone), and other phytotoxic substances. Shoots and roots of a sorghum-sudangrass hybrid (cv. Trudan 8) were collected 10, 20, 30, 40, and 50 days after emergence. Four concentrations of aqueous extracts from the shoots and roots (0, 0.4, 2, and 10 g L-1, w/v) were used to treat seeds of lettuce (Lactuca sativa), tomato (Lycopersicum sculentum), purslane (Portulaca oleracea), and pigweed (Amaranthus retroflexus). Seed germination of lettuce, tomato, and pigweed was inhibited by extracts from sorghum-sudangrass shoots at 10 g L-1 when made from sorghum-sudangrass plants 20 days or less in age. Seed germination of purslane was not inhibited by any sorghum-sudangrass extract. Growth of the four species evaluated were systematically inhibited when treated with 10 g L-1 extracts from sorghum-sudangrass shoots harvested up to 10 days after emergence.

2018 ◽  
Vol 13 (38) ◽  
pp. 1954-1958
Author(s):  
Roballo de Moura Danielle ◽  
Costa Guarana Araujo Emmanoella ◽  
Henrique Alves Borges Cesar ◽  
Henrique Barbosa Araujo Luan ◽  
Viana de Lima Tarcísio ◽  
...  

2018 ◽  
Vol 11 ◽  
Author(s):  
Aurelio Scavo ◽  
Alessia Restuccia ◽  
Gaetano Pandino ◽  
Andrea Onofri ◽  
Giovanni Mauromicale

It is known that the presence of weeds causes serious losses to the agricultural production, both in quantitative and qualitative terms. The major problem in modern agriculture is the environmental impact of synthetic herbicides and the increase in herbicide-resistant weed species. Allelopathic compounds can be used to develop a sustainable weed management system based on natural products. The objective of this study was to evaluate the allelopathic potential of leaf aqueous extracts (40 and 80%) obtained from Cynara cardunculus L. plant species on seed germination and mean germination time of six common weeds in Mediterranean agroecosystems: Amaranthus retroflexus L., Diplotaxis erucoides (L.) DC., Portulaca oleracea L., Lavatera arborea L., Brassica campestris L. and Solanum nigrum L. Effects varied with the weed species and the concentrations of the extracts. On average, the aqueous leaf extracts significantly reduced the final percentage of seed germination compared to the control for A. retroflexus (-58.1%), D. erucoides (-43.9%) and P. oleracea (-42.5%). The rate of germination decreased with increasing extract concentration. In C. cardunculus L. var. sylvestris the autoallelopathic activity also was demonstrated. These results are very promising in order to produce a bioherbicide based on C. cardunculus allelochemicals.


2003 ◽  
Vol 60 (3) ◽  
pp. 477-480 ◽  
Author(s):  
Warley Marcos Nascimento

Lettuce (Lactuca sativa L.) seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB) were incubated at temperatures ranging from 15° to 35°C at light and dark conditions. Other seeds were imbibed in dark at 20°; 25°; 30°; and 35°C for 8 and 16 hours and then transferred to 20 or 35°C, in dark. Seeds were also incubated at constant temperature of 20° and 35 °C, in the dark, as control. In another treatment, seeds were primed for 3 days at 15°C with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25°C. Seeds incubated at 20°C had 97% germination, whereas seeds incubated at 35°C did not germinate. Seeds imbibed at 20°C for 8 and 16 hours had germination. At 35°C, seeds imbibed initially at 20°C for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25°C for 16 hours, germinated satisfactory at 35°C. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20°C. Primed seeds had 100% germination at 35°C, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.


2016 ◽  
Vol 7 (1) ◽  
pp. 104
Author(s):  
Carlos Alberto Gonsiorkiewicz Rigon ◽  
Adriana Tourinho Salamoni ◽  
Luan Cutti ◽  
Adalin Cezar Morais de Aguiar

This study aimed to evaluate the allelopathic activity of aqueous extracts of castor bean (Ricinus communis L.) leaves on germination and initial growth of canola (Brassica napus L.) and radish (Raphanus sativus L.) seedlings. Two experiments were conducted, usingcanola seeds for the first, which was installed in a 2x7 factorial scheme (with two photoperiods – dark and light and seven extracts concentrations - 0, 1, 2, 4, 8, 16 and 32%). The second experiment consisted of an evaluation of radish seed germination submitted to seven concentrations of the extracts in the dark photoperiod. The germination of the canola seeds was reduced in the dark, and the use of extracts at concentrations of 16% and 32%inhibited seeds germination for both studied photoperiods. The radish seed germination was completely inhibited when the concentration of 32% was used, however, at the concentrations of 4, 8 and 16% a reduction on rootand hypocoyl development of the seedlings were observed, affirming the high allelopathic potential of castor bean aqueous extracts on canola and radish.


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