treatment with 40, 50, 60 and 70℃ hot water respectively; sacrification seed coat combining with temperature-accelerated stratification (0-4℃ 16 h and 10-15℃ 8 h); cold stratification (0-4℃) and temperature-accelerated stratification (0-4℃ 16 h and 10-15℃ 8 h).
The induced rate of the secondary dormancy differed from the treatments and the incubation conditions. The germination percentage of seeds stratified in(23±2)℃ was 10.3%,while it was up to 44.7% after the acid scarification,GA_3 soaking and cold stratification.
Results are as follows:The optimum seed germination temperature of Iphigenia indica is about 25℃,the optimum lighting period is more than 8h,the optimum photoproton is either red or yellow light,the optimum sowing depth is less than 0.5cm,the optimum soil moisture content is about 70% and the optimum cold stratification time is about 60～80 d.
After the 6th week of cold stratification, the activity of superoxide dismutase(SOD) content had a drop tendency, but malondialdehyde(MDA) just was opposite.
(3) Effect of cold stratification on dormancy-breaking of the three species and the on their tolerance to salt. The freshly matured seeds of H. strobilaceum, K.
The seed dormancy of Iris pseudacorus can be removed by GA_3,the pretreated seeds with 50 mg/L GA_3 had 84.4% germination. Cold stratification for 30 and 90 days can raise the germination rate of Iris ensata and Iris laevigata to 94.4% and 87.8% respectly.
Both the H 2SO 4 and cracking pretretments increased the air permeability and the mechanical restraint of the seed coat. After cold stratification over winter in sand moistened with 250 mg·L -1 GA 3 Solution, the pretreated seeds had 82.4% gremination, while the control seeds did not germinate or only few germinated.
After the H 2SO 4 pretreatment increased the air permeability and the mechanical restraint of the seed coat. After cold stratification over winter in moistened with 500mg·L -1GA 3 solution, the pretreated seeds by concentrated H 2SO 4 for 11 hours had 38.9% germination, while the control seed did not germination.
Dormancy was broken by a 2 to 6 months period of cold stratification.
The dormancy could be broken by cold stratification only.
Dormancy was interrupted in cold stratification at temperatures between +1 and +6°C.
In summary, seeds of S.?marilandica exhibit physiological dormancy, which can be alleviated by exposure to light, after-ripening and/or cold stratification.
We recommend that cold stratification be targeted towards species with strong dormancy or used across a wider range of species when seed supplies for restoration are limiting.
Tetracentron sinensis is a valuable tree which is rare. Its seeds have not dormancy. Its reaction to light is different at temperatures, at 25℃ no lightdemanding, at 24—33℃ (most at 28—30℃) light-favored and at 10—20℃ light can promote germination. Optimum germination temperature is 25℃; Seeds which had been cold stratification could germinate in 1.4—8.2℃. KNO_3 could partly relieve temperature demand in seeds germination, GA had this action in just a little.
Populus bolleana Lauche is one of the important species in Xinjiang. The difficulty we have met is lower survival rate in asexual propagation. This paper tries to find out the change of endegenous inhibitor and activity of partial enzymes before and after cold stratification. The influece of plant somatotropin and plastic cover on rooting of cutting has been learnt as well. At the same time, the morphological and anatomical characters were observed. All of these provided some scientific basis for developing...
Populus bolleana Lauche is one of the important species in Xinjiang. The difficulty we have met is lower survival rate in asexual propagation. This paper tries to find out the change of endegenous inhibitor and activity of partial enzymes before and after cold stratification. The influece of plant somatotropin and plastic cover on rooting of cutting has been learnt as well. At the same time, the morphological and anatomical characters were observed. All of these provided some scientific basis for developing cutting survival rate of Populus bolleana Lauche.
The germination rates of seed,embryo and embryonic axis of Prur.ua davi-diana in relation to endogenous ABA,IAA and exogenously applied GAs and BA during the processes of cold stratification and dry storage at room temperature have been studied.Sixteen weeks of dry storage resulted in only a slight reduction of ABA levels in the seed coat,but reduced that in the embryo from 303.82ng/g.FW to 92.15ng/g.FW.At the same time the IAA level in both seed coat and embryo decreased slightly.These seeds germinated...
The germination rates of seed,embryo and embryonic axis of Prur.ua davi-diana in relation to endogenous ABA,IAA and exogenously applied GAs and BA during the processes of cold stratification and dry storage at room temperature have been studied.Sixteen weeks of dry storage resulted in only a slight reduction of ABA levels in the seed coat,but reduced that in the embryo from 303.82ng/g.FW to 92.15ng/g.FW.At the same time the IAA level in both seed coat and embryo decreased slightly.These seeds germinated readily but appeared dwarf thereby implying inhibition of epicotyl growth.However,10 weeks of cold stratification apparently was enough to reduce the ABA level to 183.70μg/g·FW in coat and 9.03 μg/g-FW in embryo,and drastically increase the IAA level in embrvonic axis from 40.24μg/g-FW to 8007.80μg/g·FW.The cold-stratified seeds gave a 100% germination rate and normal seedlings,implying that the IAA might be necessary for normal growth of peach epicotyl.The experiments also showed that GA3 and GA3+BA could partly replace chilling in breaking dormancy of epicotyl and hypicotyl.A tentative mechanism for phytohormone control of dormancy and germination of peach seeds has been discussed.
cold stratification
低温层积
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