Evaluation of performance and stability of new sources for tolerance to post-emergence herbicides in lentil (

Abstract

Context Yield losses in lentil (Lens culinaris ssp. culinaris Medik.) caused by weeds are estimated at 20–80%. In the absence of effective broad-spectrum herbicides, the menace of weed has emerged as a serious yield constraint in lentil. Aims Identification of tolerance to two broad-spectrum post-emergence herbicides, imazethapyr and metribuzin. Methods 221 lentil accessions were screened at the experimental research station of the International Center for Agricultural Research in the Dry Areas, Terbol (Lebanon) over four crop seasons (2014/15–2018/19). During the 2014/15 season, a preliminary screening experiment was conducted with 221 lentil accessions in an alpha lattice design with two replications, where accessions were treated at the pre-flowering stage at 150% of the recommended dose of imazethapyr (112.5 g active ingredient/ha) or metribuzin (315 g active ingredient/ha). Based on the preliminary results, 38 accessions were selected for further evaluation. In subsequent testing, the selected accessions were screened at 100% and 150% of the recommended doses of imazethapyr or metribuzin. Key results Herbicide treatments delayed the flowering time and maturation of tested lentil accessions. The plant height of selected tolerant accessions was reduced by 15% and 8% in the plots treated by imazethapyr and metribuzin, respectively. Reduction index (RIsy) was an effective tool to select for herbicide tolerance. Stability analysis indicated that two accessions (IG4400 and IG5722) performed under high rainfall environments while two other accessions (IG323 and IG4605) were adapted to low rainfall environments. Conclusions Four accessions (IG323, IG5722, IG4400, IG4605) were identified as independently tolerant to metribuzin and imazethapyr. Implications The identified herbicide-tolerant accessions can be used to develop herbicide-tolerant cultivars.

Assessing the Stability of Herbicide-Tolerant Lentil Accessions (Lens culinaris Medik.) under Diverse Environments

“…Herbicide treatment with imazethapyr and metribuzin delayed flowering and maturity in lentils, which is consistent with previous research in lentils [ 7 ], chickpeas [ 8 ], and fava beans [ 26 ]. This delay in maturity was explained by Gaur et al [ 8 ] as a slowdown in the crop growth rate occurred after herbicide treatment due to starvation and blockage in acetolactate synthase catalyzed reactions [ 27 ].…”

“…Seed yield was lower in environments treated with imazethapyr or metribuzin than in environments not treated with herbicides. Similar findings have been previously made in lentils [ 6 , 7 ], fava beans [ 26 ], and chickpeas [ 31 ]. Furthermore, biological yield per plant (BY) at Marchouch in 2015/16 was lower than at Terbol in 2018/19, which was followed by Marchouch in 2016/17 due to low precipitation in January at Marchouch in 2015/16 and well-distributed precipitation from December to February at Marchouch in 2016/17 during the vegetation growth phase.…”

“…This delay in maturity was explained by Gaur et al [ 8 ] as a slowdown in the crop growth rate occurred after herbicide treatment due to starvation and blockage in acetolactate synthase catalyzed reactions [ 27 ]. Furthermore, herbicide-tolerant fava beans [ 26 ] and lentils [ 7 ] accessions were affected by the herbicide treatment, but subsequent plant growth led to recovery, resulting in further delay of flowering and maturity time.…”

“…Weeds are one of the most damaging biotic stresses to lentil productivity causing severe yield losses of up to 95% in North Africa and Western and Central Asia [ 5 , 6 ]. Weeds compete with lentils throughout their life cycle due to their shallow roots, poor early vigor, and slow vegetative growth, especially during the cool season [ 7 ]. Pre-emergence herbicides are effective in controlling weeds early in crop growth, but weeds germinating after crop emergence at the pre-flowering stage pose a threat to lentil production [ 8 ].…”

“…These herbicides can control a broad spectrum of annual and parasitic weeds [ 13 ], but they are phytotoxic to existing lentil genotypes. Therefore, it is necessary to develop herbicide-tolerant lentil cultivars with stable yields under a variety of conditions [ 6 , 7 , 11 , 14 ]. However, the wide adaptability of these accessions must be proven in order to include them in commercial farming at a large scale [ 15 ].…”