Study On Drought Tolerance And Morphological Characteristics Of Chrythanthemum Motifolium Ramat. For Medicine

The paper has observed the process of flower bud differentiation.Four cultivars of Chrysanthemum morifolium Ramat.for medicine were cultivated in plastic pots.Effect of water stress on their photosynthetic characters and photosystemâ…¡activity have been researched.The physiology and quality of "hongxinju" which have been treated under different water conditions during flower bud differentiation as well as in pre-anthesis stage have been studied.The results are as following:1.The flower bud differentiation of C.morifolium for medicine can be divided into nine stages,which are undifferentiated stage,Initial stage of flower bud differentiation, early stage of involucral bract differentiation,late stage of involucral bract differentiation, early stage of floret primordium differentiation,late stage of floret primordium differentiation,early stage of corolla formation,middle stage of corolla formation,late stage of corolla formation.2.Water stress has an important influence on the photosynthesis and photosystemâ…¡activity of "changbanju","hongxinju" and "xiaobaiju" during anthesis.With water stress increasing,the net photosynthetic rate,stomatal conductance and transpiration were decreased.Intercellular CO₂ concentration was trended to decreased and then increased with water stress increasing.While the water use efficiency and stomatal limitation were trended increased and then decreased.The main reason caused the decreasing of net photosynthetic rate was stomatal limit under light drought and moderate drought treatments, while the decreasing of net photosynthetic rate was mainly caused by non-stomatal limit under heavy drought treatment.With the increasing of water stress,the PSâ…¡activity of "hongxinju" was decreased.While "hongxinju" and "changbanju" were trended to increased and then decreased.The tolerance of "xiaobaiju" is weaker than "hongxinju" and "xiaobaiju". 3.During pre-anthesis stage,membrane permeability as well as content of malondialdehyde(MDA) and proline were increased with the increasing of water stress, while the content of chlorophyll was decreased.Content of chlorogenic acid and total flavonoids was decreased with the increasing of water stress during flower bud differentiation.While the content of chlorogenic acid and total flavonoids was trended to increased and then decreased with the increasing of water stress in pre-anthesis stage.The content of chlorogenic acid and total flavonoids were both the highest under light drought treatment,which were increased by 73.36%and 20.64%compared to the control.The content of the two active components under heavy drought treatment were both significantly lower than control.Water stress during flower bud differentiation has an important influence to the quality of medical C.morifoliuml.High water content in soil and extreme water stress are not propitious to the accumulation of total flavonoids and chlorogenic acid,while light drought can stimulate the accumulation of the two active components;chlorogenie acid.A conclusion can be got from this research that water stress have an important influence to the physiological and biochemical,photosynthesis and quality of medical C. morifolium,medical C.morifolium through increasing the concentration of proline for osmoregulation to keep its normal physiology from being hurt from water stress.At the same time,medical C.morifolium by the means of adjusting its stomatal movement, increasing its stomatal conductance,and enhancing its water use efficiency to decrease the hurt to photosynthesis from water stress.Soil water condition during flower bud differentiation and pre-anthesis has an important influence to the quality of medical C. morifolium.Sufficient water supply during flower bud differentiation and light drought during preanthesis can enhance its quality.