Study On Water Consumption Characteristics And Drought Resistance Of Three Wild Flower Shrubs In Hebei Province

Hebei province has a rich resources of wild flower shrubs.Many of them have characteristics of high ornamental value,low water consumption and strong drought resistance.If these resources can be used effectively in urban gardens,it can not only enrich the species of garden ornamental plants,but also save water for irrigation and reduce the cost of garden maintenance.In order to explore the effects of drought stress on water consumption characteristics and drought resistance of three wild flower shrubs of Philadelphus pekinensis,Lespedeza bicolor and Lonicera maackii in Hebei Province,we used biennial treelets as materials to study the changes of water consumption,growth parameters,physiological characteristics,photosynthetic pigments,photosynthetic parameters,photoresponse curve and fast chlorophyll fluorescence parameters under different levels of drought treatments with CK(75%~80% of MFC),W1(65%~60% of MFC),W2(50%~45% of MFC),W3(35%~30% of MFC)and lingering drought of pots or ground.We made a comprehensive evaluation of three species by the methods of attribute analysis and principal component analysis,expecting to discover the differences of water consumption characteristics and the drought-resistance ability among them.The main results were followed:(1)With the decrease of soil moisture content,the daily water consumption and water consumption rate of the three shrubs were decreased gradually.For example,after 15 days of lingering drought treatment in pot,the daily water consumption of all three plants were lower than CK,decreasing by 210%,226.3%,200% respectively.The water consumption of three species of shrubs had a great difference,the daily water consumption of them under CK,W1,W2 treatments is in the order of Lespedeza bicolor > Lonicera maackii >Philadelphus pekinensis.But under W3 treatment,the daily water consumption of three species of shrubs had no obvious difference.In different soil moisture treatments,the diurnal variation of water consumption and water consumption rate presented single peak of all three plants(The peak point was around 12:00).With the decrease of soil water,the peak of them decreased significantly.Meanwhile,the peak of Lonicera maackii under W3 treatment had been advanced.In CK,W1,W2 treatments,the correlation coefficients between daily water consumption and the environmental factors of all three plants was significantly,it was in the order of solar radiation >air temperature >relative humidity(negative).But in W3 treatment,the daily water consumption of all three plants had not significantly related with the environmental factors.(2)Under drought stress,the growth parameters of all three plants was obviously decline.The correlation analysis shows that: the height,total leaf areas,total biomass and RWC of all three plants were positively correlated with the soil moisture content.And the specific leaf weight of all three plants was negatively correlated with the soil moisture content.The mild and moderate drought is beneficial to increased the root shoot ratio of all three shrubs.For example,in W1,W2 treatments,the root and crown ratio of Philadelphus pekinensis was increased 32.7% and 71.7% when it compared with CK.In the late of lingering drought,the total leaf areas of Lespedeza bicolor had a great reductions.With the decreased of soil water content,the photosynthetic pigments content had been gradually decreased.Under drought stress,the Chla/b of all three shrubs were increased.Such as in W1 treatment,the Chla/b of Lespedeza bicolor were increased by 15.3% than CK.(3)Under drought stress,the relative conductivity and WSD of three shrubs were all rised.For example,In W3 treatment,the relative conductivity and WSD of Philadelphus pekinensis were increased by 108.3%?66.7% respectively.Under drought stress,the leaf water potential of all three shrubs were decreased compared with CK.The diurnal variation curves were presented “V” form,the lowest point was around 11:00-13:00.At 13:00,the leaf water potential of Philadelphus pekinensis,Lespedeza bicolor,Lonicera maackii were decreased by 33.1%?62.4%?89.2% than CK.(4)Drought stress treatments had a significant impact on photosynthetic parameters of all three shrubs.In CK,W1,W2 treatments,the diurnal variation curves of Pn,Tr and Gs were presented bimodal curve of all three shrubs,the peak points were around 10:00and 14:00,16:00;the diurnal variation curves of Ci was presented “V” form,and the lowest point was around 12:00-14:00.With the decreased of soil water content,the Pn?Tr?Gs were rised gradually,the Ci was decreased gradually.All of the three shrubs had relatively high light saturation point and light compensation point.The LSP,Pmax,Rd,AQY of all three shrubs were positive correlation with soil water content.On the contrary,the LCP of all three shrubs were negative correlation with soil water content.For example,in W3 treatment,the LSP,Pmax,Rd,AQY of Lonicera maackii were decreased by 28.7%,289.2%,180.7%,150% than CK,and the LCP was increased by 357.7% than CK.(5)The Fo of all three shrubs was increased and the Fm,Fv/Fo were decreased with the decrease of soil water content.For example,in W3 treatment,the Fo was increased by24.6% and the Fm,Fv/Fo were decreased by 24.2%,48.4% respectively than CK of Philadelphus pekinensis.In W1,W2 treatments,the Fv/Fm of all three shrubs were withinthe range of 0.75-0.85.But in W3 treatment,the Fv/Fm of all three shrubs were significantly decreased than CK.With the decreased of soil water content,the ?Po,?o,?Eo,ABS/RC,TRo/RC were decreased and the ?Do was increased.The tendency of ETo/RC of Philadelphus pekinensis and Lonicera maackii were increased first and then decreased,in contrast the tendency of DIo/RC was decreased first and then increased.In W1 treatment,the ETo/RC was reached maximal value of them,it was increased by 3.82%,2.6% compared with CK.And with the decreased of soil water content,the ETo/RC were decreased gradually;the DIo/RC were increased gradually of Lespedeza bicolor.(6)The membership function was used to analysis.We concluded that the membership values of Philadelphus pekinensis,Lespedeza bicolor and Lonicera maacki were 0.5,0.52,0.51.It indicated that all three shrubs had medium tolerance to the drought.The drought resistance is in the order of Lespedeza bicolor > Lonicera maackii >Philadelphus pekinensis.In severe drought,the order of drought resistance of all three shrubs were Lonicera maackii(0.3)> Lespedeza bicolor(0.28)> Philadelphus pekinensis(0.26).So Lonicera maackii had the strongest ability to survive in the extreme drought environment.In different soil moisture treatments,the order of the membership values of all three shrubs were CK> W1> W2> W3.(7)In conclusion,the lowest soil water content of maintain normal growth is65%~60% of MFC for the biennial Philadelphus pekinensis and Lespedeza bicolor;65%~60% of MFC for the biennial Lespedeza bicolor.