Seed morpho-physiological trait diversity and its association with herbicide resistance in Alabama Italian ryegrass (Lolium perenne L. ssp. multiflorum) populations

Authors: YADAV, ANKIT - Auburn University; RUSSELL, DAVID - Auburn University; GANIE, ZAHOOR - Fmc Corporation; Price, Andrew; MAITY, ANIRUDDHA - Auburn University

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Wide diversity in plant adaptive traits such seed size and dormancy generally stems back to raid invasion and adaptation potential in a weed species. Italian ryegrass is a significant weed species in winter crops such as wheat and summer crops such as corn, soybean, and peanut in Alabama. In this study, diversity in seed morpho-physiological traits—such as seed length, awn length, seedling length, 100-seed weight, and seed dormancy was assessed in the Weed Bionomics Lab at Auburn University in 65 Italian ryegrass populations collected from Alabama in 2023. Significant diversity was observed among the populations for 100-seed weight, seed length, awn length, and seedling length. Germination speed was significantly lower in the populations with high initial dormancy (>30%) compared to medium (15-30%) and low dormancy group (<15%) at 0 and 3 months after harvesting. Additionally, the relationship between herbicide resistance status and seed morpho-physiological traits in these populations was explored. A significant positive association was observed between seed dormancy and the number of survivors following glyphosate and clethodim treatments. The observed diversity in morpho-physiological traits could be the reason of enhanced adaptability of Italian ryegrass, and its correlation with herbicide resistance indicates directional selection for specific seed morpho-physiological traits exerted by repeated use of similar modes of action.

Technical Abstract: Wide diversity in plant adaptive traits such seed size and dormancy generally stems back to raid invasion and adaptation potential in a weed species. Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] is a significant weed species in winter crops such as wheat and summer crops such as corn, soybean, and peanut in Alabama. In this study, diversity in seed morpho-physiological traits—such as seed length, awn length, seedling length, 100-seed weight, and seed dormancy was assessed in the Weed Bionomics Lab at Auburn University in 65 Italian ryegrass populations collected from Alabama in 2023. Significant diversity was observed among the populations for 100-seed weight (61.8-295.8 mg), seed length (3.5-6.43 mm), awn length (0-7 mm), and seedling length (0.5-38.6 cm). Germination speed was significantly lower in the populations with high initial dormancy (>30%) compared to medium (15-30%) and low dormancy group (<15%) at 0 and 3 months after harvesting. Additionally, the relationship between herbicide resistance status and seed morpho-physiological traits in these populations was explored. A significant positive association was observed between seed dormancy and the number of survivors following glyphosate (P < 0.01) and clethodim (P < 0.01) treatments. The observed diversity in morpho-physiological traits could be the reason of enhanced adaptability of Italian ryegrass, and its correlation with herbicide resistance indicates directional selection for specific seed morpho-physiological traits exerted by repeated use of similar modes of action.