Abstract
The current paper presents the results of a study on the effects of aqueous extracts from five weed species (Amaranthus retroflexus, Cirsium arvense, Convolvulus arvensis, Echinochloa crus-galii, Setaria verticillata) on germination and initial growth in Raphanus sativus L. The following indicators have been analyzed: indices of germination (the germination percentage; the speed of germination; the speed of accumulated germination and the coefficient of germination rate), the length of the root and hypocotyls, the pH of aqueous extracts, the UV-Vis absorption spectra of aqueous extracts. The results of the investigations showed the following aspects: the aqueous extracts reduced the values of calculated germination indices and root growth in the first ontogenetic stages of the test species; the pH of the extracts was slightly acid to neutral. Qualitative spectrophotometric analysis indicated the possible presence of phenolic and organic compounds in the extracts. C. arvense, S. verticillata and E. crus-galii presented the most pronounced effect on germination and growth processes.
Highlights
IntroductionWeeds compete with cultivated plants for different environment factors (water, mineral elements, soil, light) and may favour the spreading of some pathogen agents and harmful animal (because they are host plants for them)
Weeds compete with cultivated plants for different environment factors and may favour the spreading of some pathogen agents and harmful animal
From a statistic point of view, the reduction of germination percentage (GP) was significant in C. arvense (10% concentration) and E. crus-galii (2% and 10% concentration) leaf extracts (Table 1 and Table 2)
Summary
Weeds compete with cultivated plants for different environment factors (water, mineral elements, soil, light) and may favour the spreading of some pathogen agents and harmful animal (because they are host plants for them). This affects the growth and the development of cultivated plants, the good carry out of the agro-technical works and determines the quantitative and qualitative reduction of the vegetal production (Chirilă, 2001; Slonovschi et al, 2001). The chemical substances with allelopathic potential are represented by secondary metabolites (phenolic compounds, terpenoids, lactones, cyanogenic glycosides, alkaloids etc.) that are synthesized in various plant organs and tissues (Rice, 1974; Kremer and Ben Hammouda, 2009). It has been proved that these substances influence other plants or communities of plants (affect the germination of seeds, the growth of plants, respiration, photosynthesis, mineral nutrition and other physiological processes) (Makoi and Ndakidemi, 2007; Kremer and Ben Hammouda, 2009)
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