Genetic variations for tolerance to heat and water stress in wild and cultivated lentils

Context
Lentil (Lens culinaris ssp. culinaris Medik.) is a key cool-season legume that suffers significant yield and quality losses under increasing heat and drought stress, particularly during its reproductive stage. With climate change intensifying the intensity and frequency of these stresses, current cultivars often fail to perform well under such conditions, necessitating the search for more resilient genetic resources.

Aims
This study aimed to identify lentil accessions from both crop wild relatives (CWR) and cultivated types, with tolerance to heat and drought stresses.

Methods
In total, 80 accessions (50 wild and 30 cultivated) were evaluated under optimal, heat-stress, and water-stress field conditions over two cropping seasons (2019/2020 and 2021/2022). Phenological and yield-related traits were recorded to assess stress responses.

Key results
Both heat and water stress had significant effect on phenology, grain yield, and biomass. Water stress caused greater yield and yield component reduction in cultivated accessions, whereas heat stress caused higher reduction in seed and pod numbers in CWR accessions. Notably, Accessions IG72532 (L. nigricans), IG72562 (L. c. odemensis), IG72830 (L. c. tomentosus), and four accessions of L. c. orientalis (IG16028, IG16038, IG136670, IG136672) were identified as drought tolerant. Additionally, seven cultivated accessions were identified as heat tolerant.

Conclusions
A wide range of genetic variation for heat and drought tolerance was observed across the lentil accessions, with certain wild and cultivated accessions performing well under extreme conditions.

Implications
The identified heat- and drought-tolerant accessions offer valuable genetic resources for lentil breeding programs aimed at improving resilience to climate change.