Evaluation of Allelopathic Effects of Decay Duration of Giradol (Chrozophora tinctoria L.) on Seedling Growth of Tomato (Lycopersicon esculentum mill.)

Plants communicate and influence the growth of other plants (or even microorganisms) through excretion of certain chemical compounds (allelochemicals) which is known as allelopathy. A number of allelochemicals has been reported from different plant species. Allelochemicals include phenolic compounds, benzoxazinoids, sorgoleone, glucosinolates, terpenes, alkaloids, momilactones, and etc. Knowledge of the composition of allelopathic materials and weeds with allelopathic properties not only can reduce the negative impacts on crop yield production but also can be used to produce bio-herbicide by allelochemicals as active ingredient. Giradol (Chrozophora tinctoria L.) is an annual summer plant that belongs to Ephorbiaceae family. Giradol contains phenolic components including tannins, saponins (8), cumarins, phenylpropanoid glycosides (5) and flavonoids. Einhelling (2) reported that phenolic compounds are the most active compounds involved in allelopathy. Therefore, giradol has allelopathic characteristic. Giradol can be found in the wide range of fields in Khorasan Razavi. The abundant presence of phenolic compounds and giradol makes the study of giradol allelopathic effects on crops necessary in this region.
In order to evaluate allelopathic potential of giradol (Chrozophora tinctoria L.) organs on growth of tomato (Lycopersicon esculentum mill.), a study was conducted by using a completely randomized design (CRD) with factorial arrangement with four replications. This experiment was carried out in pots and consisted of organs at 4 levels (root, stem, leaf and total plant without inflorescence) and decay durations at 8 levels (0, 15, 30, 45, 60, 75 and 90 days decay and control). Samples of different organ plant of giradol were mixed separately with 3-liter pots with 1% m/m ratio. In order to apply decay period treatments, plant samples were added to the soil for 90 days of decay treatment. 15 days later, plant samples of 75 days of treatment were added to the required soil. The remaining treatments were applied at intervals of 15 days. Therefore, after 90 days, the soil was prepared for treatments of decay period (samples under the greenhouse condition at 28 °C / day and 20 °C per night during decay period). Then, the number of 10 Tomato seeds of falat cultivar were cultivated at the surface of soil in each pot. After 75 days (before flowering), the plants were harvested from the soil surface. The plant samples were oven-dried at 75 °C for 24 hours and weighed accurately by weight measuring tools with a precision of 0.0001 g. SAS 9.1 software was used for statistical analysis and Excel software for preparing graphs. Mean comparisons were performed with a protected LSD test at the level of 1%.
Analysis of variance of decay duration of giradol on dry weight of tomato showed the significant effects (p The results revealed that decay duration and interactions between periods of decay and body type had a significant effect on tomato seedling dry matter. Our findings also demonstrated that selection of proper plant date can decrease allelopathic effects of residue giradol on tomato growth.