Understanding the Response of Water and Hormonal Stress on Seed Germination and Early Seedling Growth in Kodo Millet (Paspalum scrobiculatum L.)

The objective of the present study was to understand and evaluate the effects of water and hormonal stresses on seed germination and early seedling growth in kodo millet crop (Paspalum scrobiculatum L.) and observations were recorded for partial seed germination and full seed germination after 6-days and 12-days of stress treatments. During water stress experiments, various concentrations of mannitol (50mM, 100mM, 250mM, 500mM, 750mM, and 1000mM) and polyethylene glycol (PEG- 5%, 10%, 15%, 20%, and 25%) respectively were employed. Results achieved during water stress treatments reveal that mannitol concentrations (250mM and 500mM) were proved to be very significant and causing promotions in seed germination and seedling growths instead of osmotic stress inhibition and therefore, after 12-days of treatments, the mean germination percentage were recorded as (100%±1.41) and (93±1.06) respectively in comparison to control (88%±0.84). However, further increased mannitol concentrations (750mM and above) were found to be lethal and seed germination (%) was found to be zero. Additionally, PEG treatments (5% and 10%) were found to cause gradual inhibitions in germination percentage (79%±0.63 and 71%±0.35) respectively. However, PEG concentrations (15% and above) were turned out to be toxic for seed germination. Furthermore, experiments were also designed to find out the responses of hormonal stresses during seed germination and early seedling growth in kodo millet and hence, abscisic acid (ABA) and gibberellic acid (GA3) in various concentrations (5mg/L, 25mg/L, 50mg/L, and 100mg/L) of each were employed. Moreover, ABA even at low concentration (5mg/ L) was proved to be very toxic and causes strong inhibitions in seed germination while in contrast, GA3 at high concentration (100mg/L) turns out to be significantly inhibitory for seed germination (47%±0.77) as compared to control (88%±0.84). Interestingly, GA3 at all tested concentrations were proved to be effective to cause significant promotions in seedling elongations.