Root Exudates of Fifteen Common Weed Species: Phytochemical Screening and Allelopathic Effects on T. aestivum L.

Through allelopathic interactions, plants may either suppress competing species or promote those that may help them better adapt to their environment. The purpose of this research was to determine how the root exudates of 15 common weeds affected the germination of wheat (Triticum aestivum L.). Every other day, 15 seeds were dispersed over Petri dishes (with filter paper) and pots (with garden soil) and treated with 1 mL and 5 mL of aqueous root exudates, respectively. Distilled water had the highest germination rate at 86.33% and the lowest at 64.00% (p = 0.001) for Commelina benghalensis in the Petri dish containing root exudates. The seed germination percentage of the pot condition was the lowest, at 68.45% (p = 0.004), for Solanum nigrum, while the control was 87.23%. Similarly, the lowest shoot length, 12.01 cm (p = 0.0025) in Mikania micrantha, and the lowest root length of 2.17 cm (p = 0.0048) in Leucas aspera, were recorded, whereas the control was 19.13 cm and 3.46 cm, respectively, in Petri dishes. In addition, the lowest shoot and root growth were 9.72 cm (p = 0.0004) in Mikania micrantha and 4.34 cm (p = 0.0019) in Spilanthes acmella, while the control was at 20.13 cm and 6.42 cm, respectively, for pot culture. Furthermore, in seedlings, biomass studies of treated T. aestivum showed elevated malonaldehyde (MDA) levels in both Petri dishes and pot cultures. However, chlorophyll a and b levels, as well as those of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD), are lower than in the control group. Both enzymes were elevated in pot cultures compared to those grown in Petri plates. The dry weight of T. aestivum seedlings cultivated in pots and Petri dishes demonstrated its considerable allelopathic influence. This research found that the root exudates of all the weeds studied could have the capacity to impede wheat seed germination as well as the development of wheat seedlings. These inhibitory effects were higher in Petri dishes than in pot cultures.