Aim : Methodology :Results : Interpretation :High temperature during sowing of cotton results in poor emergence and high seedling mortality, thus leading to poor crop stand and reduced yield. Improvement in germination by seed priming may combat this problem as this physiological technique results in faster and synchronous seed germination. Hence, studies were conducted to evaluate the effect of different temperature regimes, seed priming and also duration of priming on germination and seedling growth to determine and exploit their usefulness in improving cotton seed germination for better seedling establishment.Seeds of cotton hybrid (Ankur 3028 BGII) were primed separately with water and KNO at different concentrations (2.5, 5.0, 7.5 & 10.0%) for 2, 4 and 6 hrs. Non-primed seeds and hydro primed seeds for 4 hrs were considered as control. Seeds for each set of treatment were placed on moistened filter paper in petri dish. Each treatment was then divided into two sub-sets for assessment of seedling response at two temperature regimes 25°C and at ambient temperature of 32-38.5°C. After 7 days, final germination percentage, root length, shoot length and fresh weight of seedling were measured at both temperature regimes. Germination count was recorded on daily basis and was used to calculate speed of germination.Primed seeds exhibited an increase in germination by 43% and 34% than control (non-primed seeds) at ambient temperature (32-38.5°C) and 25°C respectively. Germination speed also improved by 61% and 67% respectively at ambient temperature and 25°C over control. Hydropriming resulted in highest germination (75.5 and 79.2%), germination speed (5.13 and 6.63 days), root length (4.68 and 6.30 cm) and shoot length (2.59 and 3.40 cm) than control at 25°C and ambient temperature respectively. Contrarily, increase in KNO concentration caused deleterious effects on root and shoot length.Cotton seed germination was higher at ambient temperature (32°-38.5°C) than 25°C and priming improved germination potential of seeds. Hydropriming was more effective than KNO for enhancing germination percentage, germination speed and seedling growth at both temperature regimes. Studies concluded that hydro priming of cotton seeds improved germination, a key factor for better crop stand having positive effect on crop survival, and consequently improved cotton productivity.

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The germination behaviour of unsoaked, hydroprimed and thiourea primed seeds (TU,750, 1000 and 1250 ppm) in water , polyethylene glycol (PEG, -0.2 and -0.4 MPa ) and NaCl (30 and 50 mM) was investigated. The percent germination and seedling growth of TU primed seeds was best compared to other treatments under stressed conditions. The root/shoot ratio increased with stress in all seedlings and vice versa for seedling vigour index. TU primed seeds exhibited the highest tolerance index (85) under - 0.2 MPa PEG treatment and 40 tolerance index under 30mM salinity stress. Priming with thiourea @1000 ppm was the most effective in ameliorating water and salinity stress.