Varietal effect on germination parameter at controlled and uncontrolled temperature in Palmarosa (Cymbopogon martinii)

Palmarosa (Cymbopogon martinii) is a major essential oil bearing crop commercially cultivated in India. However, the potentiality of its commercial cultivation is restricted due to the supply of poor quality seed material, i.e. poor seed germination percent/vigour and lack of knowledge about the seed rate for nursery raising/direct sowing and viability period under storage conditions. Seed germination tests of varieties PRC-1, Trishna, Tripta, Vaishnavi were carried out in Petri plates under two temperature regimes: uncontrolled, i.e. room temperature (average minimum 27 °C–average maximum 39 °C) and controlled and constant (15 °C, 20 °C, 25 °C with 16 h light and 8 h dark photoperiod). Maximum germination percentage and germination energy percent were recorded in ‘Trishna’ (34.25 and 8.56), followed by ‘PRC-1’ (34.25 and 8.56), ‘Tripta’ (15.75 and 3.94) and ‘Vaishnavi’ (10.25 and 2.56) on final count day at controlled and constant temperature. The corresponding data were recorded (26.00 and 6.50), followed by (25.50 and 6.37), (9.50 and 2.37) and (10.00 and 2.50) under uncontrolled temperature. Differential behavior of the said varieties under different temperature regimes was attributable to their genetic make-up. Results showed that day 2 and days 3–4 was the best for first count, day 5 and days 6–7 for final count and day 5 and days 6–7 for germination period at uncontrolled and controlled and constant temperature, respectively.