بررسی اثر دگرآسیبی عصاره آبی و دوره پوسیدگی اندام‌های گوش‌بره(Chrozophora tinctoria L.) بر خصوصیات جوانه‌زنی و رشد گیاه‌چه هندوانه (L. Citrullus lanatus)

To evaluate the allelopathic potential effects of giradol (Chrozophora tinctoria L.) organs on seed germination and seedling growth characteristics of watermelon (Citrullus lanatus L.), two experiments were carried out separately as a factorial in a complete randomized design with 4 replications; this study was carried out at Research Laboratory of Weed and Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, in 2014. The first experiment was performed in Petri dishes; it  consisted of the giradol organs extract at 4 levels (root, stem, leaf and total plant without inflorescence) and their aqueous extract concentrations at 11 levels (0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10%); the second experiment was performed in the pots consisting of giradol 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 decay days in control). The concentration of the aqueous extract had a significant effect on all germination traits. The watermelon seedling growth and organ type had a significant effect on all traits except the mean germination time, root dry weight, and total biomass. The maximum effect of the extract on the measured traits was related to the highest concentration. In comparison with the control, germination percentage, germination rate, seed vigor, root length, stem length, root length/stem length ratio, root and shoot dry weight, and the seedling total weight were reduced by 67.42, 68.62, 85.08, 64.31, 51.27, 29.27, 71.67, 76.88 and 68.83 %, respectively. Also, the average time needed for the 50% germination was increased by 13.63%. The most and least inhibitory effects were in the leaf type and root extract, respectively. Decay duration, type of plant organs, and their interactions had a significant effect on the dry weight produced by watermelon. Even though increasing decay duration to 60 days led to decrease in the dry weight but decay durations of greater than 60 days exhibited a smaller decrease in dry weight. Overall, the results of these two experiments showed that the aqueous extract and the residue of decayed leaves had the most significant effect on germination, seedling growth, and dry weight. Therefore, management and control are necessary to reduce the potentially harmful allelopathic impacts of giradol on watermelon plants.