Species identification and morphological trait diversity assessment in ryegrass (Lolium spp.) populations from the Texas Blackland Prairies

Abstract

Ryegrass (Lolium spp.) is a troublesome weed in major wheat producing regions in the U.S. High diversity and adaptive potential are known to contribute to its success as a weed species and also create difficulties in correct species identification in fields. The objective of this research was to characterize diversity for 16 different morphological traits among 56 Lolium populations collected from wheat (Triticum aestivum L.) production fields across the Texas Blacklands region and identify specific Lolium species based on taxonomical characteristics. Populations were highly diverse (both at inter- and intra-population levels) for the traits studied, and a taxonomical comparison with USDA-GRIN reference samples revealed that all the populations were variants of Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] with a few offtypes of perennial (Lolium perenne L.) or probable hybrids between the two species. Hierarchical clustering grouped the populations into 6 clusters based on their similarities for the morphological traits investigated. Principal component analysis showed that the variability for yield traits greatly contributed to the total diversity. Pre-flowering plant height (stage 10 on Feekes scale) was positively correlated with tiller count, shoot biomass, spike count, but not with total seed count/plant, whereas plant height at maturity (stage 11.3-11.4 on Feekes scale) was highly correlated with total seeds/plant. Further, basal node color was positively correlated with plant growth habit, regrowth rate, and leaf color. Leaf blade width was positively correlated with survival to pinoxaden and multiple herbicides, whereas, spike count was negatively correlated with survival to mesosulfuron. The high levels of intra- as well as inter-population variability documented in this study indicates the potential of this species to rapidly adapt to herbicides, and emphasizes the need for implementing diverse management tactics including the integration of harvest weed seed control.

Delineating multivariate divergence, heritability, trait association and identification of superior omega-3-fatty acid specific genotypes in linseed (Linum usitatissimum L.)

“…Clustering of linseed accessions together regardless of their source supports the possibility of a common progenitor but separation by geographical or ecological isolation mechanisms as reported by KUMAR et al (2020) in pearl millet. The genotypes from the different geographical location falls under different clusters didn't rules out the pollen-mediated gene flow in linseed (JHALA et al, 2011) and ryegrass (MAITY et al, 2021). So in the present study weak patterns among geographical regions/origins were observed but, more importantly, germplasm with specific characteristics was identified and clustered (YOU et al, 2017).…”

Pollen‐mediated flow of herbicide resistance genes in Beckmannia syzigachne

“…The double exponential decay model was more suitable to describe the experimental data, and the maximum gene flow predicted by the model was 3.15%. Overall, the estimated value of PMGF for B. syzigachne was in a similar range as other self‐pollinated grass species such as Johnsongrass (13.7% at 5 m), 37 barnyardgrass (0.01% at 50 m), 38 and much lower than the PMGF observed in major outcrossing weeds, which is usually greater than 50% 31,39 …”

Seedbank management through an integration of harvest-time and postharvest tactics for Italian ryegrass (Lolium perenne ssp. multiflorum) in wheat

“…Italian ryegrass is a major weed in wheat production worldwide, and is reported to reduce wheat grain yields as much as 92% (Appleby and Brewster 1992;Bararpour et al 2017;Hashem et al 1998;Liebl and Worsham 1987). This species exhibits high genetic diversity, leading to wide plasticity in plants as well as seed traits that allow for wide adaptability (Maity et al 2021a(Maity et al , 2021bTerrell 1968). In the United States, this species is an important weed in small grain production across several states, including Oregon (Appleby and Brewster 1992;Appleby et al 1976), Washington (Lyon et al 2016), North Carolina (Liebl and Worsham 1987), and Texas (Stone et al 1999).…”

“…In Washington state, Italian ryegrass is reported to have shattered approximately 42% of the total seed by wheat harvest (Walsh et al 2018). Under controlled greenhouse conditions in College Station, Texas, Italian ryegrass seed shattering at full maturity ranged from 5% to 54% among different biotypes without any crop competition (Maity et al 2021a), but the upper range of seed shattering could be much higher under field environments. The degree of weed seed shattering can also vary across different geographical locations (Schwartz-Lazaro et al 2021).…”