Search Results (3)

Root exudates play a critical role in enabling plants to respond to environmental stresses and mediate information exchange within the rhizosphere. These compounds regulate plant–rhizosphere interactions and significantly influence the structural and functional properties of the rhizosphere micro-ecosystem. Under continuous cropping systems, allelochemicals derived from root exudates progressively accumulate in the root zone, thereby contributing to the development of continuous cropping obstacles. In this study, root exudates were collected from wolfberry (Lycium barbarum L.) and four forages under controlled conditions to test their effects on seed germination and seedling growth in mangold (Betu vulgaris L.) and wolfberry, as well as on the root rot pathogen. Our research shows that forage root exudates could promote wolfberry seedling growth. White clover (Trifolium repens L.) and alfalfa (Medicago sativa L.), especially, could have their growth increased by up to 61% and 90% (p < 0.05). Wolfberry root exudates could promote the seed germination and seedling growth of white clover and mangold, the seed germination of Ryegrass (Lolium perenne L.), and the seedling growth of alfalfa. In addition, mangold root rots were identified as Molds, Aspergillus niger, and Fusarium solani and wolfberry root rots were Mucor cirrus, Rhizopus, Fusarium oxysporum, and Fusarium solani. What is more, wolfberry root exudates could promote Fusarium plaque expansion and mycelial growth. Ryegrass inhibited the growth of Mucor, Fusarium putrum, and oxysporum, and alfalfa and white clover promoted the plaque expansion of Rhizopus, Aspergillus niger, and Fusarium fulcrum, but inhibited the mycelial growth of related pathogens; mangold root exudates could inhibit wolfberry root rot, which affects interspecific relationships. This study provides robust technical support for elucidating interspecific relationships and promoting the development and application of the wolfberry-forage intercropping system. Full article

Allelopathy plays a major role in agricultural production, influencing plant protection, crop yield, and crop rotation systems. This study investigated the effects of root exudates on 3105c alfalfa (Medicago sativa) seeds and seedlings to identify crops with strong and weak allelopathic potential. The results revealed that corn (Zea mays L.) (T1) exhibited the strongest allelopathic effects, whereas soybean (Glycine max (Linn.) Merr.) (T10) exhibited the weakest effects. T1 promoted seed germination by increasing radicle length and the simple vitality index. Both T1 and T10 promoted 3105c seedling growth and enhanced antioxidant capacity, albeit through different mechanisms. T1 primarily increased antioxidant capacity by elevating ascorbate and dehydroascorbate levels while reducing malondialdehyde content. In contrast, T10 enhanced antioxidant capacity by increasing soluble sugar and protein levels via hydroxyl free radical inhibition. These findings demonstrate that the allelopathic properties of corn effectively promote alfalfa growth by enhancing seed germination and improving physiological stress resistance. Full article

In this study, the allelopathic properties of Medicago sativa L. (alfalfa) seedling exudates on the germination of seeds of various species were investigated. The compounds responsible for the allelopathic effects of alfalfa were identified and characterized by employing liquid chromatography ion mobility high-resolution mass spectrometry. Crude exudates inhibited the germination of seeds of all various plant species tested. Overall, nine compounds in alfalfa were identified and quantified. The most predominant compounds were a hyperoside representing a flavonoid glucoside, the non-proteinogenic amino acid canavanine, and two dipeptides, identified as H-Glu-Tyr-OH and H-Phe-Glu-OH. The latter corresponds to the first finding that dipeptides are exuded from alfalfa seedlings. In addition, the antibacterial and antibiofilm activities of alfalfa exudate and its identified compounds were elucidated. Both hyperoside and canavanine revealed the best antibacterial activity with minimum inhibitory concentration (MIC) values that ranged from 8 to 32 and 32 to 256 µg/mL, respectively. Regarding the antibiofilm action, hyperoside and canavanine caused a decline in the percentage of E. coli isolates that possessed a strong and moderate biofilm-forming potential from 68.42% to 21.05% and 31.58%, respectively. Studies on their inhibiting effects exhibit that these major substances are predominantly responsible for the allelopathic and antimicrobial effects of the crude exudates. Full article