| The exploitation of wild Astragalus membranaceus var.Mongholicus can easily cause soil erosion,and the influence on ecology can not be ignored.Therefore,it is of great significance to advocate artificial cultivation of Astragalus membranaceus var.Mongholicus.Artificial cultivation can reduce the influence of human excavation on natural forest land.Using foliage of Astragalus membranaceus var.Mongholicus feeding livestock can reduce grazing damage to natural grasslands.During deep harrowing the roots can also be sold as medicinal materials,which can bring economic benefits.In the production practice,there were many hardships to overcome: seeds of Astraglus membranaceus var.Mongholicus were hard to germinate and irregular of emerge.Focus on causes of seed dormancy,using simple and practical methods to improve germination rate makes great sense.This paper attempts for the following aspects to proceed:(1)To explore the relationship between seed and seed coat structure;(2)Comparing several dormancy breaking methods,the best method to break dormancy was selected.Effects of different methods on the seed germination rate,germination potential and germination index were discussed in this paper;(3)Comprehensive analysis some factors affecting the germination and dormancy breaking such as time,temperature and dry/wet condition.The main results were as follows:(1)Seed coat of Astragalus membranaceus var.Mongholicus have the typical hard seed structure characteristics mainly includes: cuticle,palisade tissue,bone-shaped cell layer,the spongy tissue;Imbibition region might be hilum and micropyle,“water gap” were exist around hilum or near micropyle make water get through.(2)During imbibition process of Astraglus membranaceus var.Mongholicus: seeds imbibition quickly has lowest germination rate,germination rate gradually increases and tends to be stable with time lasting.Seeds could imbibe within 12 hours can not germination.However,germination rate was soared when seeds could imbibition after soaking 24 hours,while seeds could imbibition after soaking 48 hours,germination rate tends to be stable.(3)Three indicators(germination rate,germination potential and germination index)were choose as a reference for comparing several methods of breaking seed dormancy:98% sulfuric acid 1min >60? warm water 2min+40? warm water 2h>80mg/L IAA 24 h.(4)Soaking seeds with warm water,variable temperatures were better than constant temperatures.The effect of different temperature to break seed dormancy were 60?>70?>80?.When variable temperature was 60?,time for 2min,5min germination rate were respectively 2.87,2.31 times than control(P < 0.01).(5)Effects of IAA on germination rate and germination potential showed as follows: effect on germination index was not obvious.Low concentration treatments increased seed germination rate,high concentration treatments of IAA inhibited germination rate.(6)Breaking dormancy by cutting seed coat combining with GA3: Soaking seeds with 900mg/L GA3 for 24 hours was the best processing method;with time increasing,germination rate was gradually reduced.(7)Time,temperature and dry/wet conditions can affect the seeds germination of Astragalus membranaceus var.Mongolicus: there has a linear relationship between germination rate and time,so does temperature.Compared with control,germination rate showed a rapid rise at first and reduce gradually with the increase of soaking time,the relationship between germination index and soaking temperature was significant positive correlation(P <0.01).There were correlation among soaking temperature,germination potential and germination index.Hot and humidity environment was more conducive to break the dormancy than high temperature and low humid. |
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