The Investigation of Allelopathic Effects of Aqueous Extract of Different Parts of the Giradol (Chrozophora tinctoria L.) on Seed Germination of Tomato (Lycopersicon esculentum mill.)

Document Type : Short Research


1 Islamic Azad University, Mashhad, Iran.

2 University of Birjand, South Khorasan Province, Birjand, Iran


Introduction: In recent years, food production known as a main challenge for increasing human population. Along with the development of agricultural systems, weed management practices have been developed to sustainable management. Allelopathy is the biochemical interaction of inhibition and promotion within plants or micro-organisms. Allelopathy considered as a mechanism of some plants was proposed firstly by Molish in 1937. Allelopathy has a broad application prospects in increasing crop production, plant protection, and biological control. There are many known allelochemicals: water soluble organic acid, straight-chain alcohols, aliphatic series, aldehydes, ketones, simple unsaturated lactone, long-chain fatty acids, multi-alkyne, naphthoquinone, anthraquinone acid, quinone compound, simple phenols, benzoic acid and its derivatives, cinnamic acid and its derivatives, coumarin, flavonoids, tannins, terpenoids, steroids, amino acids, peptides, alkaloids, cyanohydrin, sulfide, glucosinolates, nucleotides. While phenolic acids and the terpenoid compounds are more common types. Giradol (Chrozophora tinctoria L.) known as an invasive annual summer plant that belongs to Ephorbiaceae family. Giradol not only can reduce the crop productivity by competition for light, water and nutrient mineral but also can decrease crop growth and productivity as it has the phenolic components such as tannins, saponins, cumarins, phenylpropanoid glycosides, and flavonoids. Thus, it may have allelopathic effects. Giradol have been reported in the wide range of fields in Khorasan Razavi province. This study was conducted for determining allelopathic effects of Giradol on tomato as the main crop being cultivated in Khorasan Razavi province.
Materials and Methods: In order to evaluate allelopathic effects of Giradol on seed germination of tomato (Lycopersicon esculentum mill.), this study was conducted in weed research lab of Ferdowsi University of Mashhad on the basis of a Completely Randomized Design (CRD) with factorial arrangement with 4 replications in 2014. The treatments consisted of Giradol organs at 4 levels (root, stem, leaf and total plant without inflorescence) and their aqueous extract concentrations at 11 level (0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10%). The plant organs were harvested from Fariman in the summer of 2014. The samples were carefully washed and then dried. The sample were ground and 10 g for each sample was added to 100 ml distilled water. The samples were shacked for 12 h, and the shaking process was done again after 72 h. The extracts were passed through the filter paper. The stoke solutions were diluted. Then, 6 ml from each extract was added to each experimental unit. The petri dishes were placed in a germinator at 25/15°C in 45/65% relative humidity with a 16/8 h day/night regime, respectively. The measuring traits were germination percent, germination rate, means of germination time, vigor, and root length, shoot length, root length to shoot length ratio, root dry weight, shoot dry weight, and seedling weight.
Results and Discussion: The result of this experiment showed that concentration of aqueous extract had a significant effect on germination percent, germination rate, means of germination time, vigor, and root length, shoot length, root length to shoot length ratio, root dry weight, shoot dry weight and seedling weight at 0.1% probability. Same results have been reported by Seyyedi et al (8) for allelopathic effect of castor bean organs on germination percent, germination rate and means of germination time of dodder. The variation response of different concentration of castor bean aqueous extract on germination of seeds dodder has been reported. The result of this experiment also showed that germination percent, germination rate, means of germination time, shoot length and root length had no significant effects by the type of plant organs whereas other trials showed significant effects. Generally, the leaf and stem water extracts had the highest negative effects on germination percent compared to the root and whole plant Giradol extracts. The same results reported by Rooffard and Omidbeigi (7) on the influence of extract concentration on the germination percent.
Conclusion: The results showed that the concentration of the aqueous extract significantly affects the germination and seedling growth. Furthermore, the extract of different organs adversely influences the germination percentage, germination rate, mean of germination time, and shoot length. It seems that proper management of Giradol weeds before and during tomato growth can lead to higher germination and more uniform plant emergence and finally can be of help for enhancing crop yield.


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