Seeds of canola (Brassica napus) cultivars "Hayola401" and "Zarfam" were primed with 14 dS m-1 NaCl solution for 24 hours at 20°C. After priming, non-primed (NP) and primed (P) seeds were sown in germination boxes containing perlite. The germination boxes were placed in greenhouse and treated with five different NaCl solutions (0.4 (control), 4, 8, 12 and 16 dS m-1), for a period of 3 weeks. Total emergence and dry weight were higher in canola seedlings derived from P seeds and they emerged earlier than NP seeds. Moreover, seeds from NP groups could tolerate up to 8 dS m-1 NaCl salinity, while the total emergence values of P groups in "Hayola401" and "Zarfam" did not decrease below 50% at 12 and 16 dS m-1 , respectively. NaCl priming enhanced proline accumulation and prevented toxic and nutrient deficiency effects of salinity because less Na + but more K + and especially Ca 2+ was accumulated in canola seedlings. As a matter of fact, Na: Ca 2+ balances of seedlings derived from P seeds were significantly lower than those of NP seeds under similar salinity levels.

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ABSTRACT.The environmental stress such as, drought are serious obstacles for field crops in further areas of the world, especially in arid and semiarid regions. In order to investigate drought stress on seed reserve utilization and seedling growth of treated seeds of mountain rye (Secale montanum), an experiment was carried out. Factorial experiment was carried out in completely randomized design with three replications. The first factor was the seed treatments (unpriming, hydropriming and osmopriming) and the second factor was drought stress. To create drought stress, polyetylenglycol 6000 (PEG 6000) in osmotic levels at 0 (as control), -0.4, -0.8, -1.2 and -1.6 MPa were used. The results indicated that for these traits: germination percentage (GP), timson index (TI), energy of germination (EG), weight of utilized (mobilized) seed (WMSR), seed reserve utilization efficiency (SRUE), seedling dry weight (SLDW), and seed reserve depletion percentage (SRDP), was a significant treatment × drought interaction. Thus hydropriming and osmopriming improvement study traits in Secale montanum under drought stress. While in higher osmotic pressure the highest seed reserve utilization were obtained from osmopriming.

Seeds ofCenchrus ciliarisL. were produced under different hydro–photo–thermal environments with and without fertilizer. Dormancy loss of spikelets and extracted caryopses was tested during dry after-ripening at 40°C and 43% equilibrium relative humidity. Caryopses had higher initial germination and lost their dormancy faster than spikelets. Dormancy of both caryopses and spikelets generally decreased with an increase of maturation temperature and fertility, whereas dormancy increased if water stress was imposed during maturation. The latter effect was smaller when the mother plants were exposed to water stress after caryopses were fully formed than when water stress cycles were applied throughout maturation. Daylength extension (to 14 or 18 h d-1) by artificial light increased dormancy of both caryopses and spikelets. The effect of long days declined when plants were exposed to natural daylight for more than 10 h d-1. The after-ripening curves were consistent with the hypothesis that dormancy periods of individual seeds are normally distributed within each seed lot. Rates of loss of dormancy were quantified by the slopes of these curves. In a given experiment, these rates were identical for caryopses but not always for spikelets that matured in diverse environments. Even for caryopses, however, the slopes varied between experiments. Therefore, the results do not support the hypothesis that a dormancy model can be applied universally to all seed lots ofCenchrus ciliaris. Methods of predicting the period of after-ripening required to achieve desired levels of dormancy for reseeding degraded rangelands are discussed.

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