Study On Drought Resistance Of Isatis Indigotica Fort

In this experiment, drought resistance of seeds and growth period of woad (Isatis indigotica Fort.) were studied using PEG6000simulating drought stress and controlling the soil Related Water Content in pot experiments. To enhance seeds and growth period of woad,three methods including ABT seed soaking, CaCl2seed soaking, Moisture-Absorbing and Drying Again and ABT and CaCl2foliar spray were investigated to enhance seeds of woad drought resistance.Compared germination rate, germination energy, germination index, radicle length, hypocotyls length parameter of ABT seed soaking, CaCl2seed soaking, presoaking and Moisture-Absorbing and Drying Again in Drought resistance test using of seed pretreatment seeds of woad, using0%,5%,10%,15%,20%PEG solution simulating drought stress. Compared woad physiological indicators, photosynthetic parameters, growth impact of ABT foliar spray, the foliar application of CaCl2and control in pot experiment in which three water gradient experiment was set up:relative soil water content of80%,60%,40%. The results are as follows:With the increasing of drought stress, woad germination rate, germination potential, germination index, electrical conductivity showed a downward trend, growth of radicle and hypocotyl was inhibited,but mild drought stress (5%PEG) can improve germination potential、germination index and promote growth of radicle and hypocotyls. CaCl2seed soaking and presoaking can increase the germination potential, germination rate, germination index. At P0, P5, P10, P20, germination potential of woad seed was respectively improved at61%,26%,12%,133%by CaCl2seed soaking. At P0, P5, germination potential of woad seed was respectively improved at45%,9%by Moisture-Absorbing and Drying Again. At P5, P15, P20, in the method of CaCl2seed soaking, germination rate of woad seed was respectively improved at23%,11%,12%. And P0,P5germination index was respectively improved at39%,22%.There was no significant effect in the enhancement of germination index, germination rate, germination potential in the method of ABT seed soaking which can promote growth of radicle and hypocotyls of woad seed, while the other two methods had no significant effect. Electrolyte leakage of woad seed were all decreased among three methods.With increasing drought stress, peroxidase activity of woad increased at first and then decreased, the malondialdehyde content continued to rise, the chlorophyll content was decreasing. Compared to mild drought stress, woad peroxidase activity increased by23%in moderate stress, and42%in severe stress; woad malondialdehyde content in moderate and severe stress, respectively increased by110%,150%. Woad net photosynthetic rate decreased with increasing drought stress, transpiration rate, stomatal conductance and intercellular CO2concentration increased at first and then decreased. Growth of woad was inhibited when subjected to drought stress, so the biomass also declined. With the increase of drought stress, leaf number downward trend.CaCl2treatment can reduced the MDA content of woad, which were reduced by40%43%24%in mild stress to severe stress.CaCl2treatment can peroxidase activity of woad by76%87%181%;. ABT treatment can improved peroxidase activity, but no significant difference.It can reduced malondialdehyde content by30%29%16%. CaCl2and ABT treatment can improve net photosynthetic rate, transpiration rate of stomatal conductance and intercellular carbon dioxide concentration of woad in which CaCl2treatment effect had significant effect, while ABT treatment was not. ABT treatment can significantly promote root growth in mild stress, thereby increasing biomass of woad; but failed to have a demonstrable effect in moderate and severe stress. CaCl2treatment can improve drought tolerance of woad, protecting their growth and development, and had a significant effect in the moderate stress.