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This study investigated the potential of moringa leaf extract (MLE) in seed priming for vigour enhancement of spring maize sown at low temperature (12 ± 1°C). The efficacy of MLE priming (3% w/v) was compared with other priming agents: kinetin (0.5% w/v), KCl (2% w/v) and hydropriming, each for 18 hours in hybrid maize cv. Pioneer-6525. Non-primed seeds were used as the control. Priming with MLE was the most effective in improving germination rate and subsequent seedling growth. This increased seedling performance was the result of reduced time to 50% germination (T50) and mean germination time (MGT), and higher final germination percentage (FGP), germination index (GI) and germination energy (GE). Similarly improved seedling growth following seed priming with MLE or kinetin was due to enhanced root and shoot lengths, the ratio of root:shoot length and maximum seedling fresh and dry weights compared with control seeds. Enhanced seedling maize performance by priming with MLE was attributed to improved chlorophyll content, amylase activity and total sugar contents under cool conditions.

Summary Reduction and delay in the germination of spring maize (Zea mays L.) may be a problem due to low soil temperatures and low water potentials. However, seed priming is used to improve rate and speed of germination, and expand temperature limits for germination under normal and stressful conditions. Therefore, the objective of this study was to assess the physiological and biochemical basis of primed maize seeds under low temperature conditions. Maize seeds were subjected to hydropriming, hormonal priming with 100 mg L

Impact of pre-sowing seed treatments on the germination and seedling vigour of rice was evaluated through investigating the biochemical changes following seed invigoration by analyzing the sugars and α-amylase activity. The seeds were invigorated by traditional soaking, osmoconditioning (-1.1 MPa KNO3) for 24 or 48 h and hardenening for 18 or 24 h. All the invigoration treatments significantly affected the germination rate and spread, fresh and dry weight of roots and shoots, shoot length, total, reducing and nonreducing sugars and α-amylase activity. Seed hardening for 24 h and traditional soaking performed the best as indicated by reduced germination time and increased germination rate, shoot dry weight and non-reducing sugars. In addition αamylase activity and total and reducing increased. Osmoconditioning failed to improve the seedling vigour.

The effects of seed hardening treatments using different salt solutions on the germination, emergence and seedling vigor in coarse and fine rice were investigated in a laboratory trial. Seeds were hardened both using tap water (referred to as hardening) and with CaCl2, KNO3, KCl, NaCl solution (osmohardening) in such way that osmotic potential of all the solutions was – 1.25 MPa. In both coarse and fine rice, osmohardening with CaCl2 performed the best compared with all other treatments as indicated by lower values of time to start germination, MGT, T50 and MET and higher values of final germination and emergence, speed and energy of germination, root and shoot length and seedling fresh and dry weight. Simple hardening and osmo-hardening with KCl were next best treatments.

The effects of pre-sowing seed treatments on the germination and emergence of fine rice and on reducing, nonreducing and total sugars and α-amylase activity were studied. Fine rice seeds were either soaked in tap water by a traditional method, hardened for 18 or 24 h (two cycles) or osmoconditioned (-1.1 MPa KNO3) for 24 or 48 h. Seed hardening (24 h) and the traditional soaking treatments resulted in a higher germination percentage, germination index and energy of germination and lower mean germination time and mean emergence time. Performance was slightly better in seeds subjected to hardening for 24 h than the traditional soaking because of lower T50 and non-reducing sugars and higher reducing and total sugars and α-amylase activity. In seeds subjected to osmoconditioning for 48 h seed performance was impaired possibly because of KNO3 toxicity.

An experiment was carried out using an upland cotton (Gossypium hirsutum L.) cv. NIAB-78 to investigate the physiological and biochemical aspects of seed deterioration during accelerated ageing. The seeds were subjected to 40-44°C and 90-95% relative humidity for 1, 2, 3, 5, 7, 10, 15 and 20 days for artificial ageing. Controlled ageing linearly decreased the germination capacity. There was a complete loss of germination at 20 days of accelerated ageing. The decline in seed germination during accelerated ageing was accompanied with the increase in mean emergence time (MET), days to 50% germination (T 50 ), electrical conductivity (EC) of solute leakage, free fat acidity and lipid peroxidation. Accelerated ageing not only affected emergence percentage and time but also decreased the seedling vigour, as is indicated by reduction in root weight, shoot weight and hypocotyl length. The cottonseed deterioration by accelerated ageing might be due to membrane disintegration and inactivation of enzymatic systems due to lipid peroxidation and increase in free fat acidity.