| Seriphidium transiliense is a xerophil shrub and is one of the reseeding species for the improvement of the degraded desert in Xinjiang.Because of wild species,the problems of low survival rate,low survival rate and low growth rate appeared after reseed ling the seeds of S.transiliense in the degraded desert grassland,which seriously affected the restoration result of the degraded desert.Those may be closely related to the seed quality and the condition of field for reseeding.Therefore,in order to ensure the quality of the seeds of S.transiliense,improving its germination rate after reseeding in degraded grassland,the changes of seed germination and seedling growth of S.transiliense were discussed under different harvest time[(the initial stage of fruiting for harvesting(H1),Postponed 5d(H2),10d(H3),15d(H4),20d(H5)and 25d(H6)],PEG stress(mass volume ratio is 0%,5%,10%,15%,20%and 25%)and NaCl stress(mass volume ratio is 0%,0.2%,0.4%,0.6%,0.8%and 1.0%)at the simulated insitu temperature(2/10℃、10/20℃、15/25℃、15/30℃)condition,and the optimum harvesting time,high tolerance concentration of drought and salt stress were determined.The main results are as follows:(1)With the delay of the harvesting period,the water content,1000-grain weight and the dry 1000-grain weight of the seeds of S.transiliense increased then decreased,and reached the highest in H4 were 14.9%,208.6 mg,177.4 mg and the difference between H2,H3 and H4 treatments was not significantly(P>0.05).It increased and then decreased for germination rate,germination energy,germination index,radicle length,germ length,seedling weight and simplified vigor index of S.transiliense which increased and then decreased with the delay of the harvesting period,and H3 and H4 reached the highest,which were respectively 59.8%～65.6%,48.4%～53.7%,12.6～13.2,15.5 mm～15.7 mm,3.2 mm～3.3 mm,1.8 mg～1.9 mg and 0.93～1.03.The low germination temperature inhibited the germination energy,germination index,radicle length and embryo length of S.transiliense seeds,but had no significant effect on seedling weight and germination rate(P>0.05).S.transiliense was suitable for harvesting at 10～15d after the initial stage of fruiting.(2)With the increase of PEG concentration,the germination rate,germination energy and germination index of S.transiliense decreased.Under 5%PEG stress,the germination rate,germination energy and germination index were 60.9%,51.1%and 12.8,respectively,and the difference was not significant compared with 0%PEG,and the germination rate decreased significantly to 34.4%～45.1%under 20%～25%PEG stress.The radicle length,the length of the germ and the dry weight of the seedlings increased first then decreased with the PEG concentration,and respectively reached the highest at 10%,5%and 15%PEG stress,the value was 26.6 mm,3.9 mm and 3.34 mg,and there was no significant difference in radicle length,germ length and seedling weight among 5%,10%and 15%PEG stress.Under the germination condition of 10/20℃,the germination rate,germination energy,germination index,radicle length,germ length and seedling weight of S.transiliense were the highest.In conclusion,the seed germination of S.was relatively good when the PEG concentration was low 5%at 10/20 ℃.(3)With the increase of NaCl concentration,the germination rate,germination energy and germination index of S.transiliense decreased,and compared with 0%NaCl,the germination rate,germination energy and germination index at 0.2%NaCl concentration significantly decreased by 26.6%,37.9%and 38.7%.The germ length and the weight of seedlings increased first and then decreased,which reached the highest respectively at 0.2%and 0.4%NaCl,the value was 3.7 mm and 1.45 mg,but there was not significant difference among 0～0.6%NaCl stress(P>0.05).The radicle length showed a downward trend,and there was no significant difference among 0%,0.2%and 0.4%NaCl.The germination characteristics of S.transiliense seed at 10/20℃ were better than that of other three temperatures.In conclusion,when the NaCl concentration was not higher than 0.2%,the seed germination of S.transiliense was relatively high at 10/20℃. |
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