This paper provides data regarding the mechanisms developed by plants (based on the biochemical interactions) in order to survive, and the use of these biochemical metabolites in sustainable agriculture systems. The research carried out highlights the effect given by loline alkaloids that were determined in low alcohol extracts of Lolium perenne, on the germination and the growing at the early development stages of the perennial grasses seedlings of Dactylis glomerata, Poa pratensis and Festuca rubra. The material plant used in bioassays consisted of roots, stems, leaves and inflorescence of Lolium perenneculese from the western part of Romania, the Banat region and seeds of Dactylis glomerata, Poa pratensis and Festuca rubra. In order to test the seed germination, the standard method was used. The growth of the embryonic rădăciniţelor and tulpiniţelor was determined by biometrizare. The seed germination can be influenced by allelopathic compounds, the allelopathic inhibiting action of the seed germination is more frequent than the stimulation. The tested extracts that were applied in three different concentrations (alkaloids concentrations = 0.668% , dilution I = 0.334%, alkaloids concentrations and dilution II = 0.083%) because the biological activity of the allelophatic compounds is dependent on a characteristics concentration step. The studies on the seed germination ability under the influence of various extracts were made by several researchers which concluded that the direct effect of the allelophatic compounds can be a stimulating effect, but often it is an inhibitory effect. Many cultivated and spontaneous species produce allelochemical compounds that reduce the growth in the seedlings. This phenomenon is mainly due to direct interference with the cell division processes or with the growth hormones. Our studies have shown that allelophatic substances can inhibit the seed germination but can affect the growth and development of the plant receivers of these substances, so that allelophatic phenomenon is a cause-effect relationship between substances with allelophatic potential and physiological response of the target plant. The performed studies results show the following aspect: Lolium perenne extracts present inhibitory allelophatic activity on the seed germination and the application of the extracts doses in different concentrations shows that as the alleophatic substances concentration increase, the inhibitory effect increase; the growth of the plants maintained in an environment treated with extracts, is lower compared to the control sample and the effect is maximal at the highest concentration.

chemical componds, allelopathy, germination bioassays, growth bioassay

Presentation: oral