Near infrared (NIR) spectroscopy was used to classify normal and artificially aged nonviable corn (Zea mays L., cv. 'Suwon19') seeds. The spectra at 1100-2500nm were scanned with normal and artificially aged single seeds and analyzed by principle component analysis (PCA). To discriminate normal seeds from artificially aged seeds, a calibration modeling set was developed with a discriminant partial least square 2 (PLS 2) method. The calibration model derived from PLS 2 resulted in 100% classification accuracy of normal and artificially aged (aged) seeds from the raw, the 1st and 2nd derivative spectra. The prediction accuracy of the unknown normal seeds was 88, 100 and 97% from the raw, the 1st and 2nd derivative spectra, and that of the unknown aged seeds was 100% from all the raw, the 1st and 2nd derivative spectra, respectively. The results showed a possibility to separate corn seeds into viable and non-viable using NIR spectroscopy.

Controlled hydration treatment of tobacco seeds enhanced seed performance greatly without additional materials associated with conventional osmotic or solid matrix priming technique. The seeds were hydrated by adding water to a level from 10 to 60% by 5% increments and incubated for 8 days at 25~circC . After the treatment, the seeds were dried to the original seed moisture content under 20~circC for 72 hours. The moisture content of tobacco seeds equivalent to 35% by the hydration treatment gave the greatest improvement in germination rate and speed compared to untreated or polyethylene glycol (PEG) primed seeds, especially at low temperature of 15~circC .

Tobacco (Nicotiana tabacum L. cv KF109) seeds were artificially aged in a controlled environment of 45~circC and 80% relative humidity condition for different duration up to 14 days before priming in polyethylene glycol 6000 solution of equivalent osmotic potential of -0.8 MPa for 8 days at 25~circC . The seeds aged only and primed after aging were germinated at 15~circC and 25~circC to observe the priming effects on the germination of aged seeds at different temperature. The germination percentage of the aged seeds was rapidly dropped starting from 8 days of aging and mean germination time (T50 ) was greatly increased, particularly in germination at 15~circC . The germination capacity was greatly restored in the primed seeds after aging, particularly in the seeds of longer aging and germinating at 15~circC .>.

Tobacco seeds (Nicotiana tabacum L. cv KF109) were primed in the polyethylene glycol 6000(PEG) solution and then stored at 5 and 25~circC under 40, 60 and 80% relative humidity (RH) conditions for six months. The effect of storage temperature and humidity on mean germination time (T50 ), longevity and germination of the primed tobacco seeds were compared. Untreated seeds (control) stored at 5~circC showed high germinability throughout the entire storage period and humidity, and a decline in germinability showed after 6 months at 60% RH and after 3 months at 80% RH when stored at 25~circC , Primed seeds retained high germinability until 6 months at 60% RH and 3 months at 80% RH when stored at 5~circC but showed a significant decline in germinability after 3 months at 40% RH, and 1 months at 60% and 80% RH, respectively when stored at 25~circC , Primed seeds were completely lost viability when stored at 25~circC under 60% RH for 6 months and under 80% RH for 3 months.

Some metabolites and embryo growth of primed tobacco (Nicotiana tabacum L. cv. ‘KFI09’) seeds were observed during priming. The seeds were primed at 15 and 25~circC for 1, 2, 3, 5, 10 and 15 days in a -0.8 MPa polyethylene glycol 6000 (PEG) solution. The time to 50% seed germination (T50 ) was greatly reduced when the seeds were primed at 25~circC when compared with 15~circC . The α -amylase activity and sugars and amino acid contents in the seeds primed at 25~circC greatly increased, while α -amylase activity was similar, and sugar and amino acid contents increased slightly in the seeds primed at 15~circC . When the seeds were primed at 25~circC , growth of the embryo which was enclosed by endosperm was detected, while the endosperm became thinner as the priming duration was extended.d

Tobacco (Nicotiana tabacum L. ‘KF109’) seeds were primed in polyethylene glycol 6000 (PEG 6000) solutions to determine a) what osmotic potential of the solution would be optimal for priming, i.e., critical potential level for preventing germination, and b) what temperature and duration would be the most effective in priming. The germination was completely prevented below -0.8 MPa of PEG 6000, that indicates a optimum water potential for seed priming. Seeds were primed for 0, 1, 2, 3, 5, 10 and 15 days at 15, 20 and 25~circC , respectively, under the-0.8 MPa PEG 6000 solution to find out the most effective temperature and duration for priming. The effectiveness of priming, particularly in germination speed, was observed more distinctly when the primed seeds were germinated at 15~circC than 2 5~circC . The greatest reduction of the time to 50% germination (T/sob 50/) was when the seeds were primed at 25~circC . The reduction rate of the T50 was rapid when primed from 1 day to 8 days and then slowed down in the seeds primed for longer than 8 days. The time from 10 to 90% germination ( T10-90 increased in the primed seeds for longer than 8 days which showed the reversed effect of synchronous germination. However, T50 was reduced continuously in the seeds even primed over 8 days. Thus, the optimum condition for tobacco seeds priming with PEG 6000 solution was -0.8 MPa in osmotic potential of the solution at 25~circC for 8 days.ays