Research On Seed Germination And The Drought Resistance Physiological Characteristics In Seeding Stage Of Artemisia Halodendron

In this study.PEG-6000 concentration control and potted water replenishment were used to study the effects of different water treatments on the Artemisia halodendrorn Turcz.ex Bess.The changes of the osmotic regulation,the antioxidant protection system and the endogenous hormones were studied under drought stress and the physiological responses of seed germination and seedling growth to drought stress were discussed.The results showed that the seeds Germination conditions and physiological drought resistance mechanism were also observed.Microscopic morphology of seed coat was observed by scanning electron microscopy.The results show that:].The germination rate of the seeds was good at 15??30?.the germination rate was higher than 70%.The germination rates were 87.5%and 88.2%.respectively,but the dark conditions inhibited the growth of radicle.The gennination rate of the seeds was 87.5%and 88.2%respectively under light and dark conditions.The drought stress promoted the growth of radicle,and the drought stress inhibited the growth of radicle.2.The indexes of plant height,true leaf number,stem diameter,root diameter,root length,leaf length,fresh weight and dry weight were significantly decreased with the increase of drought treatment intensity.The increase of drought stress increased the aboveground biomass and underground biomass,and the ratio of underground biomass to total biomass of plant was decreased under low intensity drought stress.Underground biomass accounted for the total biomass increased under high intensity drought stress.3.With the increase of drought stress,the changes of physiological indexes in Artemisia halodendron seedlings were as follows:the content of Pro and MDA increased with the increase of drought stress intensity,and the highest value in PEG concentration of 30%was 65.15?g·g-1 and 2.83?mol·g-1 respectively.SOD,POD and CAT activities of the three kinds of enzyme activity and soluble protein content were first increased and then decreased,highest SOD was at PEG concentration of 20%.which was 121.32U·g-1.The highest POD,CAT and soluble protein content were at PEG concentration of 25%,which were 95.27 U·g-1,49.32 U·g-1 and 0.43Mg·g-1.4.The relative evapotranspiration,chlorophyll,Pro,MDA,soluble sugar,soluble protein,SOD,POD and CAT were all increased with the increase of drought stress intensity at the same treatment time.The maximum increases were 68.7%.4.1 mg·g-1.102.3?g·g-1,2.05 ?mol·g-1,4.36?mol·g-1,0.36 ?g·g-1,112.1 U·g-1,97.5 U·g-1 and 35.3 U·g-1.Under the same drought stress intensity,the relative conductivity,chlorophyll.Pro.MDA,soluble sugar,SOD,POD and CAT increased with the increase of treatment time.and the soluble protein content increased first and then decreased.5.The contents of endogenous ABA in leaves and roots were within the range of(53.5ng·g-1?38.3ng·g-1)and(71.3ng·g-1?153.1ng·g-1)and contents of GA3 changed in the range of(6.4ng·g-1?11.2ng·g-1)and(6.3ng·g-1?9.2ng·g-1),respectively.With the decrease of the water content of the substrate.ABA and GA3 content showed a significant increase trend.The contents of endogenous IAA in leaf and root were changed in the range of(72.1ng·g-1?115.1ng·g-1)and(47.5ng·g-1?95.4ng·g-1)and contents of ZR changed in the range of(7.2ng·g-1?3.4ng·g-1)and(6.5ng·g-1?11.3ng·g-1)respectively.With the decrease of matrix water content.IAA and ZR content showed a significant reduction trend.The water content decrease of the matrix changes the ratio between different endogenous hormones of Artemisin halodendron,IAA/ABA and ZR/BA under HS were significantly decreased,but had little effect on GA3/ABA,GA3/IAA,ZR/GA3 and ZR/IAA.