Iranian Journal of Seed Research

Introduction: Generally speaking, plants contain various organic compounds which could influence the behavior of plant communities. These compounds are basically secondary metabolites which are found in various parts of plants such as rhizomes, roots, stems, leaves, flowers, fruits and seeds. The objective of the present study was to investigate the hetrotoxicity potential of different organs of Euphorbia maculata weed on traits of germination, chlorophyll and carotenoids pigments of wheat cultivars.

Material and Methods:  In this experiment Euphorbia maculate weed was collected at full maturity stage from the Moghan region, located in Ardebil Province. Then various organs of Euphorbia maculate such as stems, leaves, and fruits were separated from each other. Another treatment namely, a mixture of different organs, was also made. This experiment was carried out as a factorial, adopting a completely randomized design with three replications in Weeds Science Laboratory of Gonbad–e- Kavous University in 2017. The first factor was wheat cultivar at two levels, consisting of Morvarid and Gonbad and organs in 5 levels (control, stem, leaf, fruit and their mixture, with equal amount of each) were the second factor. For the bioassay experiment, from each organ and their mixture, 5% suspension (w/v) was prepared, using distilled water. 10 ml of concentrated extract of each organ was applied on 50 sterilized seeds of cultivars of interest in a petri dish containing filter paper. After 7 days, traits such as rate and percentage of germination, radical length, shoot length, seed length vigor index, chlorophyll a, b and total content and carotenoids content were measured.

Results:  The results showed that unlike the Morvarid cultivar, germination rate and germination percentage of the Gonbad cultivar significantly decreased, using aqueous extract of various organs of Euphorbia maculata and their mixture. The results also showed that the inhibition effect of fruit and leaf organs on the rate and germination percentage of the Gonbad cultivar were higher than that of other organs and their mixture. According to the results, stem, leaf and fruit extracts had a higher toxic effect on the radical length, compared with the shoot length of the Gonbad cultivar. The results of mean comparison also showed that seed length vigor index of the Morvarid and Gonbad cultivars decreased, due to hetrotoxic compounds of all organs of Euphorbia maculate. In terms of this trait, the highest significant decrease was found in the Gonbad cultivar, which was about 84.13%, compared with the control. In this study, the decreases in the photosynthesis pigments of total chlorophyll and carotenoids in both cultivars with aqueous extract of stem, leaf and fruit organs of Euphorbia maculata were different. The highest decrease of pigments was found in the fruit organ of the Morvarid cultivar. However, aqueous extract of mixed organs had a significant decrease and increase on the content of these pigments in the Morvarid and the Gonbad cultivars, respectively, as compared with the control. This may be due to differences in the quantity and quality of some allelochemicals as well as different reactions of the cultivars.

Conclusions:  Given the evidence of the hetrotoxicity potential of various organs of Euphorbia maculata weed on traits of germination as well as the chlorophyll and carotenoids content of wheat cultivars, it is advisable to exploit huge biomass generated by these luxuriantly growing weeds as bio-compounds in sustainable agriculture.