ABSTRACT

The research was aimed at standardization of osmopriming to enhance seed germination and field emergence in artificially aged seeds of pigeonpea [Cajanus cajan (L.) Millsp.] cv. TS-3R. Seeds were subjected to osmopriming with PEG 6000 at osmotic potentials of -1.0, -1.5 and -2.0 MPa for three different durations (6, 12 and 24 h) and were incubated separately at temperatures of 20 and 25 ºC. The study demonstrated that varying osmotic potentials and priming durations significantly influenced physiological traits such as seed germination, mean germination time, germination index, time to 50 % germination, seedling vigour and electrical conductivity of seed leachate. Specifically, seeds primed at an osmotic potential of -2.0 MPa showed increased germination percentage, germination index and seedling vigour while displaying reduced mean germination time, time to 50 per cent germination and electrical conductivity of seed leachate. The optimal treatment was found to be 12 h of priming at 25 ºC with -2.0 MPa osmotic potential, yielding the most favourable results across the measured traits. Overall, osmoprimed seeds exhibited superior quality characteristics compared to both aged and control (dry) seeds.
Biochemical analyses were conducted to explore the relationship between lipid peroxidation and antioxidant activity. The findings indicated that seed priming significantly enhanced the quality of aged seeds. Increased seed vigour was linked to a reduction in highly reactive free radicals, which were mitigated by antioxidant enzymes. Lipid peroxidation, indicated by the production of volatile aldehydes and malondialdehyde, was counteracted by the activities of superoxide dismutase and catalase enzymes. This study clearly showed that the treatment involving incubation at 25 ºC for 12 h at -2.0 MPa osmotic potential effectively mitigated seed deterioration more rapidly than treatments at other osmotic potentials.