Allelopathic Effects of Cereal Rye on Weed Suppression and Forage Yield in Alfalfa

Abstract

Cereal rye (Secale cereale L.) is widely used as cover crop because of its allelopathic effects and effectiveness in weed suppression. In the Southeastern US, rye is traditionally grown for winter grazing in dormant bermudagrass pastures, where alfalfa (Medicago sativa L.) is increasingly planted as a companion crop. The effect of cereal rye on alfalfa as a succeeding crop is not known. Therefore, the objective of this study was to evaluate the effect of cereal rye on alfalfa seedling emergence, growth, forage yield, and weed suppression in field conditions. Rye was planted in the fall (mid-October) and the biomass was harvested in spring (March) followed by disking and incorporation of the remaining stubble in the soil. Alfalfa seed was planted four weeks later. The experiment design was a split-plot design with the main plots being no-rye and after-rye and the sub-plots being alfalfa cultivars. Ten alfalfa cultivars were planted in three replications after-rye and three replications with no-rye as a previous crop. In the establishment year, weed density was significantly (p < 0.01) lower in the after-rye alfalfa plots by nearly 77%. Alfalfa seedling counts were also significantly lower (p < 0.01) among the cultivars planted in the after-rye block compared to the no-rye, with a seedling count reduction between 35% and 64%. Reduction in total dry biomass yield varied from 15% to 43% among the cultivars planted in the after-rye block. The results of this study also suggest that the allelopathic effect of rye on alfalfa may not persist beyond the establishment season, but the enormous yield reduction in the first production season may constitute a costly economic penalty in terms of forage production. There was variation in the response of different alfalfa cultivars to the effect of rye residue as indicated by the variation in the magnitude of reduction in stand count and forage yield. This warrants more research in multi-location trials with and without rye in order to establish whether there is genetic variation in alfalfa germplasm in their tolerance to cereal rye allelopathy.

Dissecting Key Adaptation Traits in the Polyploid Perennial Medicago sativa Using GBS-SNP Mapping

“…In southern environments, temperatures at this time of the year are still very favorable for active growth of alfalfa. Fall 2016 was a very unusual season in Georgia because of the historical drought in the region (Adhikari et al, 2018 ), which led to a very limited growth and erratic regrowth after clipping in both experimental sites. This could be the main reason that the two parents did not exhibit differences in their heights for this season (Table 2 ) and a few QTLs were detected based on the 2016 fall data.…”

The perception and use of cover crops within the island of Ireland

“…Cover crops are grown due to their diverse array of benefits ranging from weed, pest and disease suppression (Adhikari, Mohseni‐Moghadam, & Missaoui, 2018; Brust, Claupein, & Gerhards, 2014; Dazzo & Garoutte, 2017; Dossey, 2010; Lord, Lazzeri, Atkinson, & Urwin, 2011), water management, including water drainage (Joyce et al, 2002; Zhang, Tan, Zheng, Welacky, & Wang, 2017), as well as water retention (Basche et al, 2016) as a result of better soil structure including soil permeability (Chen & Weil, 2010; Chen, Weil, & Hill, 2014). Cover crops also positively enhance nutrient cycling and reduce leaching (Aronsson et al, 2016; Justes et al, 2012; Teixeira et al, 2016) and can provide over‐winter forage for livestock (Kälber, Meier, Kreuzer, & Leiber, 2011; Keogh, McGrath, & Grant, 2012).…”

Whole-Genome Sequencing on 220 Alfalfa (Medicago sativa L.) Accessions Identified Association of DREB1C Gene with Fall Dormancy Height

“…Seventy-one QTL related to FD traits have been identified, and 15 of them can be detected in more than one environment (Li et al 2015). Another study identified 45 significantly associated QTL for FD (Adhikari et al 2018). Both of these groups found that FD and winter hardiness have independent inheritance and could be improved independently.…”