Studies On Dormancy And Germination Physiology Of Four Carex Species

Seeds of C. humilis var. nana, C. lanceolata, Carex breviculmi and Carex giraldiana which have good ornamental characteristic and potential market value were studied to determine their dormancy and germination physiology. The study contents included seeds' biology characteristics(seed morphology, 1000-seeds weight, viability, moisture content, respond to temperature and photoperiod etc.), seeds' dormancy breaking methods(mechanical treatment, GA3 treatment, concentrated sulfric acid treatment, stratification treatment, ect.), observtion of seed coat surface via SEM, seeds' water absorption feature, physiology and biochemistry indexes variation during stratification(endogenous hormones ABA,GA,IAA,ZR content, amylase activity, soluable suger and starch content, soluable protein content).The conclusions were as follows:1. Seeds of C. humilis var. nana, C. lanceolata and Carex giraldiana were dormancy, exclude Carex breviculmi. Seeds of C. humilis var. nana, and C. lanceolata were high dormancy level and Carex giraldiana was low dormancy level. The dormancy type of Carex seed was combined dormancy. Fluctuating temperature was helpful for germination of Carex seeds. The optimal germination temperature was 15/25℃( 25℃in day time 15℃in night. The same as below) for C. humilis var. nana, C. lanceolata and Carex breviculmi and 20/30℃for Carex giraldiana. The germination percentage under optimal temperature was 34%, 39%,95% and 81%; the viability was 90%,88%,99% and 94%; germination index was 1.99, 2.54, 5.97 and 2.73 for C. humilis var. nana, C. lanceolata Carex breviculmi and Carex giraldiana respectively.2. Light was benifical for germination of all four Carex species' seeds but light was not an essential condition for their germination. So four Carex species seeds were called light-favored seeds.3. Mechanial treatment, GA₃ treatment, concentrated sulfuric acid treatment and cold stratification treatment could realse Carex seeds dormancy level to certain extent, among which cold stratification treatment was proved to be most effective. After stratification for 150 days germination percentage increased to 84%,81%,93% and 87% and germination index increased to 11.31,12.60,18.15 and 5.20 respectively. 4. Observation of seeds's surface under SEM indicated that sulfuric acid treatment made seeds' surface spiltted and pits emerged so that the resistant force of germination was decreased. However these features did not observed with ck.Under SEM cells of ck were arranged in a compact way. Seed coat more or less prevented seed from absorbing water . The hinderace of seed coat for germination was not because of the lag of water absorbtion but because of mechanical resistance.5. The mechanical restraint of seed coat and embryo endogenous hormone ABA inhibiton were the main reasons for Carex seed dormancy. During stratification treatment endogenous ABA content significantly decreased, amylase activity and soluable suger content increased and starch content decreased. These physiology indexes variation indicated the conversion of seed's dormancy state to non-dormancy state.