In a recent study published in the journal PLOS One, a team of researchers has identified six lentil species that are tolerant of alkaline and saline soil. The group consisted of researchers from various institutes of the Indian Council of Agricultural Research (ICAR) and the Chandra Shekhar Azad University of Agriculture and Technology, Kanpur.
India stands second in the total global consumption of lentils after Canada, consuming about 1,139 thousand tonnes of lentils annually. Lentil is a cheap source of vegetarian protein and other vital nutrients like carbohydrates and fibres. However, its yield is severely affected by alkalinity and salinity of the soil, caused due to the accumulation of sodium and carbonate/bicarbonate ions. This increase drastically increases the pH level too and as a result, hampers the plant’s germination, growth, and productivity. As the alkalinity of the soil continues to rise due to the use of excess fertilisers and alkaline water for irrigation, it is now paramount to grow crops that are tolerant to soil alkalinity.
In the current study, the researchers selected 285 lentil genotypes, or the genetic constitution of an organism, and screened them for their capacity to tolerate alkalinity. The seeds were first allowed to grow in nutrient-rich alkaline water with a pH of around 8.8-9.1. The seedlings were then transferred to the fields where the soil pH ranged between 9 and 9.5.
A plant is tolerant of alkalinity and salinity in the soil when all its seedlings survive in the field, and the plant has no visible deposition of salts on its body. There should also be no significant reduction in its growth, no wilting of leaves or leaf chlorosis where enough chlorophyll is not produced. The researchers found that out of the 285 lentil varieties that they screened, only six of them showed the above traits, thus proving their resistance to alkalinity and salinity stress.
So, what makes some lentils species tolerant? To understand this, the researchers analysed the diversity in the genes of these 285 lentil genotypes. They studied microsatellite markers—small lengths of repetitive DNA sequence widely used in mapping the location of genes for particular traits—of these lentils. “Evaluation of genotypes to locate alkalinity tolerance gene(s) is important for incorporating the tolerance in high yielding lentil varieties,” say the researchers.
The resistant varieties described in the study might benefit lentil breeders in developing stress-resistant varieties.
“The wild lentil populations showed a relatively higher level of tolerance and thus can be used for incorporating genes to improve alkalinity stress tolerance of the cultivated one either through conventional breeding or genetic engineering. They can also be used in breeding programs to develop new tolerant genotypes for growing in alkaline soils”, say the authors, commenting on the potential applications of their findings.