Response Of Rhizome Expansibility And Accumulation Of Nitrogen And Phosphorus Of Two Ecotype Kentucky Bluegrass To Water And Nitrogen And Phosphorus Fertilization

As a kind of cold-turfgress and typical rhizome grass,kentucky bluegrass is mainly and widely used in the cold and dryland lawn in the north of china.Rhizome,as an important organ for the storage and nutrient reproduction of kentucky bluegrass,played a very important role in improving the surface expansion,encroachment and the ability of soil consolidation.Water and fertilizer were the key factors affecting the growth performance of kentucky bluegrass and other rhizomatous turfgrasses.Suitable water and fertilizer supply can not only promote the vegetative propagation of rhizome type grass,but also be of great significance for improving lawn quality,ornamental and adversity resistance,maintaining lawn landscape,saving water and fertilizer resources and reducing the cost of lawn maintenance.However,there are few reports about the response of growth and expansion of kentucky bluegrass rhizome and accumulation and utilization of nutrient elements to water and fertilizer regulation.Therefour,response of rhizome expansibility,nitrogen and phosphorus accumulation,distribution and related enzyme activities of two ecotype kentucky bluegrass to four different water levels and three nitrogen and three phosphorus levels,were studied in a pot experiment with single planting using‘Tianzhu'ecotype kentucky bluegrass and‘Yuzhong'ecotype kentucky bluegrass as indicators.The main results were as follows:1.The evapotranspiration,coverage area,number of tillering and biomass aboveground of‘Tianzhu'ecotype kentucky bluegrass and‘Yuzhong'ecotype kentucky bluegrass decreased with soil moisture decreasing.The number of rhizomes,stem internode length,the longest rhizome length,diameter of rhizomes,surface area of rhizomes,volume of rhizomes,biomass of rhizomes,biomass underground and root/shoot ratio increased with soil moisture decreasing till and then decreased.The optimal water level for expansibility of aboveground rhizomes of two ecotype kentucky bluegrass was 90%-75%WHC?Water holding capacity?,while the optimal water level for expansibility of underground rhizomes was 75%-60%WHC.The water requirement of‘Yuzhong'ecotype kentucky bluegrass was higher than that of‘Tianzhu'ecotype kentucky bluegrass.2.90%⁷5%WHC was more conducive to the accumulation of aboveground nitrogen and phosphorus of two ecotype kentucky bluegrass;75%⁶0%WHC was more conducive to the distribution of nitrogen and phosphorus in the part of underground and enhanced of NR?Nitrate reductase?,NIR?Nitrous reductase?,GS?Glutamine synthase?and GOGAT?Gluta-mic acid synthase?activities,improved the nutrient utilization efficiency of nitrogen.The accumulation of nitrogen in kentucky bluegrass increased with the increasing of nitrogen metabolism related enzymes?NR,NIR,GS and GOGAT?activities in different organ.3.Between nitrogen application 0¹5 g·m^-2,nitrogen is the main factor of aboveground expansion of two ecotype kentucky bluegrass,and it increased with the increase of nitrogen.N3P3(N:15 g·m^-2,P:25 g·m^-2)is the optimal treatment.4.The interaction between phosphorus and nitrogen had significant influence on the growth of kentucky bluegrass underground rhizomes.Between phosphorus application 0²5g·m^-2,it increased first and decreased with the increase of phosphorus.For expansibility of underground rhizomes increased with the increase of nitrogen of ecotype kentucky bluegrass‘YuZhong'.Ecotype kentucky bluegrass‘TianZhu'is less affected by application of nitrogen.Moderate or low of nitrogen and low of phosphorus,high nitrogen and phosphorus promoted rhizome extensibility.Low nitrogen and high phosphorus restrained rhizome extensibility.The optimal fertilizer were N1P1(N:5 g·m^-2,P:5 g·m^-2)and N2P1(N:10g·m^-2,P:5g·m^-2)on expansibility of rhizome to two ecotype kentucky bluegrass‘TianZhu'and‘YuZh-ong'.The optimal fertilizer were N1P1 and N3P3 on expansibility to two ecotype kentucky bluegrass‘TianZhu'and‘YuZhong'.The fertilizer requirement of‘Yuzhong'ecotype kentucky bluegrass was higher than that of‘Tianzhu'ecotype kentucky bluegrass.5.Fertilizer was conducive to the accumulation of nitrogen and phosphorus by the tested two ecotype kentucky bluegrass.The greater amount of nitrogen applied,the more favorable the accumulation and distribution of nitrogen in plants and aboveground parts,while enhanced of NR,NIR,GS and GOGAT activities;Low nitrogen application is beneficial to the distribution of underground and use efficiency of nitrogen of two ecotype kentucky bluegrass.Low Phosphorus increased phosphorus accumulation in two ecotype kentucky bluegrass,the activity of ACP is enhanced with the increase of phosphorus application.The accumulation of nitrogen and phosphorus has a significant or very significant positive correlation with the activity of related metabolic enzymes.