Certain Western Himalayan populations of buckwheat (Fagopyrum spp.) exhibit differential drought tolerance during seedling establishment

Buckwheat (Fagopyrum spp.) is a promising crop owing to its significant nutritional and pharmaceutical value as well as its ability to thrive under diverse stressful growth conditions. Such ability could be expected to vary in a genotype specific manner. In the present study, seedling establishment (seed germination and seedling growth) performance of Fagopyrum esculentum (1) and Fagopyrum tataricum (3) genotypes from Kinnaur (Himachal Pradesh, India) has been compared under water deficit stress imposed by polyethylene glycol (PEG) application. The latter differentially influenced the seed germination of the stated Fagopyrum genotypes. Lower PEG concentrations stimulated seed germination in all genotypes to varying extents whereas at 20% PEG, genotype-specific suppression of the same was evident. Thus, F. tataricum (Whitechabru) proved most tolerant with only 14.6% inhibition of germination at this concentration after 15 days, while F. tataricum (Sobrash) was most sensitive with 53.9% inhibition. Similar sensitivity pattern was observed in case of seedling growth. Further, mitochondrial functionality, measured through TTC reduction ability indicating dehydrogenase activity, was differentially influenced in the seeds, implying its likely involvement in germination responses to drought. For example, at 10% PEG, TTC reduction was enhanced by 25.3% in F. tataricum (Whitechabru) and suppressed by 12.7% in F. tataricum (Sobrash). Furthermore, PEG treatment led to enhanced proline contents in the tolerant F. tataricum (Whitechabru) compared to others, especially after 7 d. Also, the reactive oxygen species (ROS) burden in terms of O2·− and H2O2 accumulation, was greater in F. tataricum (Sobrash) than in F. tataricum (Whitechabru). PEG treatment differentially altered the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) in different genotypes; the changes did not align directly with their observed drought tolerance. However, the role of antioxidant defence in all genotypes is apparent.