Abstract
Recent studies have demonstrated that the presence of belowground neighbours induces varied morphological and biochemical responses in plants. Plant allelopathic activity is elicited by the presence of competitor seedlings or competitor root exudates. However, it is unknown whether allelopathy also influences root recognition behaviour in weed–crop interaction. To assess barnyardgrass response to the presence of allelopathic rice roots, we conducted a greenhouse experiment of barnyardgrass–rice mixed culture, including barnyardgrass monoculture, barnyardgrass mixed with the allelopathic rice line PI312777 and barnyardgrass mixed with the nonallelopathic rice cultivar Liaojing-9. Our results showed that the presence of allelopathic rice roots enhanced root allocation and tissue density (RTD) of barnyardgrass, whereas it decreased root biomass, total root length, specific root length (SRL) and topological index (TI), compared to barnyardgrass grown in monoculture; moreover, there was a significant correlation of topological index with root foraging precision and competition. Therefore, the presence of allelopathic rice roots affected the barnyardgrass root morphology, nutrient foraging and competition, suggesting that allelopathy plays a key role in root recognition behaviour of barnyardgrass–rice competitive interaction.
Highlights
Roots are pivotal for plant performance because they forage for nutrient and water, but they fix in the soil
Our results showed that the presence of allelopathic rice roots enhanced root allocation and tissue density (RTD) of barnyardgrass, whereas it decreased root biomass, total root length, specific root length (SRL) and topological index (TI), compared to barnyardgrass grown in monoculture; there was a significant correlation of topological index with root foraging precision and competition
We studied barnyardgrass root recognition, focusing on the effects of allelopathy by measuring root biomass and root allocation, specific root length, root tissue density and root topological index in plants subjected to different treatments
Summary
Roots are pivotal for plant performance because they forage for nutrient and water, but they fix in the soil. Root overproduction in response to nutrient patches is a ubiquitous adaptive strategy to efficiently take up nutrients that can promote plant growth to gain a competitive advantage at a given time [1,2,3]. Plants can regulate their root systems (belowground competitive traits) through recognition of neighbouring roots [4,5,6]; the growing interest in the study of root recognition behaviour. Root recognition might be important in altering root function traits of growth and morphology [7] Improved knowledge about root recognition is necessary to have a better understanding of plant production in natural and agricultural systems.
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