| Nitrogen is one of the essential elements in crop growth and development,be able to participate in the synthesis of a variety of organic compounds(such as amino acids,small molecular peptides,enzymes,alkaloids,etc.),plays a vital role in crop quality and yield,in addition,nitrogen is an important component of nucleic acids,phospholipids,proteins and some growth hormones in plants.Phosphorus is one of the most important components of nuclear proteins,phospholipids,and nucleic acids.Phosphorus is one of the essential nutrients for crop growth and development,phosphorus plays a key role in photosynthesis,sugar metabolism,energy metabolism and enzymatic reaction.In recent years,the excessive application of nitrogen and phosphorus fertilizer is not only a waste,but also pose a threat to the environment.To this end,we studied the characteristics of nitrogen and phosphorus utilization of several common pear rootstocks,in order to provide a basis for screening suitable pear rootstocks.The experiment was conducted at the horticultural experiment station of Shandong Agricultural University in Shandong province from 2015 to 2016,Four kinds of one-year-old pear rootstocks[Pyrus betulifolia Bge.,Pyrus calleryana Dcne.,Pyrus pashia D.Don.,Pyrus xerophila Yü] were used to study the characteristics and characteristics of absorption,the characteristics of nitrogen uptake and utilization were studied by 15 N isotope tracer technique,the main results are as follows.1.Four kinds of one-year-old pear rootstocks[Pyrus betulifolia Bge.,Pyrus calleryana Dcne.,Pyrus pashia D.Don.,Pyrus xerophila Yü] were used to study the characteristics and characteristics of absorption,distribution and utilization of labeled NH415NO3 and 15NH4NO3.The results were as follows: The maximum biomass of Pyrus xerophila Yü was 5.22 g,significantly higher than other rootstocks,the biomass of four rootstocks from high to low were Pyrus xerophila Yü >Pyrus pashia D.Don.>Pyrus calleryana Dcne.>Pyrus betulifolia Bge.;The root surface area,total rool lengh and root tips of Pyrus pashia D.Don.were the largest of the four,while Pyrus betulifolia Bge.were the least.The maximum rootactivity of Pyrus xerophila Yü was 72.04 μg·g-1h-1,significantly higher than other rootstocks,The root vigor of four rootstocks from high to low were Pyrus xerophila Yü>Pyrus pashia D.Don.>Pyrus calleryana Dcne.>Pyrus betulifolia Bge..The contribution of 15 N to the total nitrogen content(Ndff)absorbed from nitrate nitrogen was higher than that absorbed from ammonium nitrogen of the organs of the four rootstocks.When the nitrate and ammonium nitrogen were labeled,the distribution of 15 N in the leaves was the highest,followed by the roots and stems.The utilization rate of nitrate nitrogen is the utilization rate of ammonium nitrogen 5.21 times,2.62 times,1.37 times,3.34 times of Pyrus betulifolia Bge.,Pyrus xerophila Yü,Pyrus pashia D.Don.,Pyrus calleryana Dcne..Nitrate utilization rate of Pyrus xerophila Yü was highest in the 4 rootstocks,significantly higher than other rootstocks.Ammonium nitrogen utilization efficiency of Pyrus pashia D.Don.was highest in the 4rootstocks,significantly higher than other rootstocks.2.Four kinds of one-year-old pear rootstocks[Pyrus betulifolia Bge.,Pyrus calleryana Dcne.,Pyrus pashia D.Don.,Pyrus xerophila Yü] were used to study the characteristics and characteristics of absorption,setting 3 nitrogen levels:no nitrogen,low nitrogen and high nitrogen.Study under different nitrogen levels 4 pear Rootstocks on 15 N absorption,distribution and utilization characteristics.The results were as follows: the total dry weight of Pyrus betulifolia Bge.,Pyrus xerophila Yü,Pyrus pashia D.Don.and Pyrus calleryana Dcne.were 1.96 g、4.24 g、2.92 g、3.32 g,The maximum biomass of Pyrus xerophila Yü was highest and significantly higher than other rootstocks.Compared with no nitrogen treatment,the proportion of total dry weight of Pyrus xerophila Yü increased in low nitrogen treatment was the least,was 10.14%;the proportion of total dry weight of Pyrus betulifolia Bge.increased in low nitrogen treatment was the highest,was 15.82%.,the proportion of total dry weight of Pyrus pashia D.Don.decreased in high nitrogen treatment was the highest,was 23.55%;Compared with no nitrogen treatment,the root surface area,root length and root tip number of the low nitrogen treatments were significantly increased,and the root surface area,root length and root tip number of different nitrogen treatments were significantly decreased.The root surface area,root length and root number of Pyrus betulifolia Bge.in different nitrogen levels were the lowest,total root surface area,root length and root number of Pyrus calleryana Dcne.in different nitrogen levels were highest.Compared with the low nitrogen treatment,the Ndffof the organs of different rootstocks decreased under high nitrogen treatment.The Ndff of all the 4 rootstocks in different nitrogen treatments showed the stem > root > leaf.The 15 N absorbed by plants were mainly distributed in leaves,and there was no significant difference in roots and stems.The 15 N utilization of the low nitrogen treatment is the high nitrogen treatment 2.40 times,1.39 times,1.43 times,1.76 times of Pyrus betulifolia Bge.,Pyrus xerophila Yü,Pyrus pashia D.Don.,Pyrus calleryana Dcne..Under low nitrogen and high nitrogen levels,the 15 N utilization of Pyrus pashia D.Don.was 6.24%、4.50%,significantly higher than other rootstocks.3.Three kinds of one-year-old pear rootstocks[Pyrus calleryana Dcne.,Pyrus pashia D.Don.,Pyrus xerophila Yü] were used to study the characteristics and characteristics of absorption.Set P0,P1,P2,P3,P4 five phosphorus levels of the test.Effects of phosphorus supply on nitrogen uptake and utilization of pear Rootstocks.The results were as follows:Different pear rootstocks showed different performance under different phosphorus levels.With the increase of phosphorus,the biomass of Pyrus calleryana Dcne.increased first and then decreased,in P2 treatment,the biomass of Pyrus calleryana Dcne.was 3.46 g,significantly higher than other treatments.The biomass of Pyrus pashia D.Don.and Pyrus xerophila Yü increased gradually with the increase of phosphorus level,the highest values were obtained under P4 treatment.Under P0 and P1 treatment,the biomass of Pyrus xerophila Yü was highest,respectively 3.89 g and 4.30 g.The root biomass of Pyrus calleryana Dcne.was the highest in P2 treatment,P0 treatment was the smallest,the root activity was the highest in P2 treatment,and the lowest in P0 treatment.With the increase of P levels,biomass and root vigor of Pyrus pashia D.Don.and Pyrus xerophila Yü increased gradually,biomass and root activity of Pyrus pashia D.Don.and Pyrus xerophila Yü were the lowest in P0 treatment,Under P0 and P1 treatment,The root activity of Pyrus xerophila Yü was highest respectively 95.86 μg·g-1h-1,111.01 μg·g-1h-1;The Ndff of roots,stems and leaves of Pyrus calleryana Dcne.increased firstly and then decreased with the increase of phosphorus level,both reached the maximum at P2 and decreased to the lowest in P4 treatment.The Ndff of roots,stems and leaves of Pyrus pashia D.Don.and Pyrus xerophila Yü increased with the increase of phosphorus level,showing a rising trend.With the increase of phosphorus level,the 15 N utilization rate of Pyrus calleryana Dcne.increased firstly and then decreased,the 15 Nutilization rate of Pyrus calleryana Dcne.was highest in P2 treatment(6.63%),in P4 treatment was lowest.The 15 N utilization rate of Pyrus pashia D.Don.and Pyrus xerophila Yü increased with the increase of phosphorus level,showing a rising trend.Under P0 and P1 treatment,the 15 N utilization rate of Pyrus xerophila Yü was the highest,5.41% and 6.27%,respectively. |
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