Comparison of selection models for classification of germplasm accessions to osmotic stress tolerance in finger millet (Eleusine coracana L.)

Finger millet is a climate resilient crop with C4 nature of carbon fixation. However, its yield improvement has been stagnated in the recent decades due to climate extremities, majorly the drought as crop is cultivated in rainfed conditions. Early seedling stage is the most crucial for seedling establishment, adequate plant population, and grain yield, which is generally affected due to failure of rainfall after the seed sowing. Screening of germplasm at early seedling stage for drought tolerance would provide the donors for crop improvement. The study was conducted at the Department of Crop Physiology, UAS, GKVK, Bengaluru, India. Forty-nine germplasm accessions were screened at the early seedling stage under laboratory conditions using PEG 8000 MW (-5.11 bars) to create physiological drought. The effect of PEG stress was evaluated considering the seed germination, seedling length, seedling vigour index and the response indices like percent reduction, drought susceptibility index and fuzzy membership function value were compared to use in selection of stress tolerant accessions. A significant reduction in seed germination, seedling length and seedling vigour index, with an increased root length and root to shoot ratio due to PEG stress was observed. Variability for root length and root to shoot ratio was higher compared to other parameters. Among the selection models, percent reduction, drought susceptibility index (DSI), and membership function value (MFV), the MFV approach was found appropriate. Using the MFV values, the accessions, GE-568, GE-4596, GE-4729, were found highly tolerant and GE-492, GE-1240, GE-1034, GE-2866, GE-3454, GE-4478 as tolerant to osmotic stress.