• Horticultural Science & Technology
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• v.18 no.3
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• pp.321-326
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• 2000

To compare germinability of primed seeds with that of water imbibed and nonprimed seeds at different temperatures, percent germination, number of days to attain 50% of the final germination percentage (T50) and mean number of days to germination (MDG) were evaluated at various temperatures ranged from $10^{\circ}C$ to $35^{\circ}C$. Primed carrot seeds in -0.50 MPa PEG 8000 showed higher percent germination at $10^{\circ}C$ or $35^{\circ}C$. Reductions in T50 and MDG values were observed at all germination temperatures when primed with the PEG. The PEG combined with 100 mM $K_3PO_4$ was not as effective as the PEG alone in improving the germinability of carrot seeds. Nonprimed lettuce seeds germinated only 2% at $30^{\circ}C$ or $35^{\circ}C$. However, priming with 50 mM $K_3PO_4$ increased germination to 40% at $30^{\circ}C$ and to 21% at $35^{\circ}C$. In contrast to the single treatment of 50mM $K_3PO_4$, priming lettuce seeds in a mixture of 50mM $K_3PO_4$ and 200 mM $KH_2PO_4$ resulted in a lower percentage of germination, but a significant greater reduction of T50 and MDG. Percent germination was increased when 200 mM $KH_2PO_4$-primed onion seeds and 100 mM $Ca(NO_3)_2$-primed Welsh onion seeds were germinated at $10^{\circ}C$ or $35^{\circ}C$. Combined treatments with $Ca(NO_3)_2$ for onion and with $KH_2PO_4$ for Welsh onion seeds did not improve percent germination, but they significantly reduced T50 and MDG.