喀斯特地区野生枇杷种质对铵态氮的吸收及利用效率差异与评价

Differences and Evaluation of Ammonium Nitrogen Absorption and Nutritional Efficiency for Wild Loquat Germplasm in Karst Area

以贵州喀斯特地区22个野生枇杷(Eriobotrya japonica Lindl.)种质的实生幼苗为材料,采用土培和营养液培养方法,对不同铵态氮水平下各材料的株高、植株干重、氮含量、铵态氮吸收量及吸收效率、氮效率以及对NH+4的最大吸收速率(Imax)、表观米氏常数(Km)和NH+4流入根系的速率(α)进行测定,分析以上指标在种质间的差异及其相互作用和相关性,并划分不同野生枇杷种质的氮效率类型。结果表明:(1)实生幼苗的干重、铵态氮吸收量及氮效率在种质间和铵态氮水平间均存在显著差异,22个野生枇杷种质植株干重、氮含量、铵态氮吸收量、铵态氮吸收效率、氮效率变异系数(CV)在高氮和低氮水平下分别为21.09%和16.87%、17.06%和20.00%、36.67%和40.21%、36.71%和40.24%、21.05%和19.21%;不同野生枇杷种质对NH+4吸收动力学参数的差异也极为显著,Imax、Km、α值的CV在高氮和低氮水平下分别达到44.64%和60.00%、73.53%和81.48%、89.58%和109.18%。(2)上述所有指标在种质间和铵态氮水平间的差异及其交互作用均达到极显著水平(P<0.01),22个野生枇杷种质实生苗的干重、氮含量、铵态氮吸收量及吸收效率、氮效率、NH+4的Imax和α值之间都表现出极显著正相关关系,Km与上述指标呈极显著负相关关系;在高氮和低氮水平下,铵态氮吸收效率对氮效率的直接通径系数最大(1.805和1.523),铵态氮的吸收效率对氮效率的直接贡献均大于氮含量和铵态氮吸收量。(3)22个野生枇杷种质可划分为双高效型、高氮高效型、低氮高效型和双低效型4种氮效率类型,分别包括7个、4个、2个和9个种质。研究发现,贵州喀斯特地区野生枇杷种质对铵态氮的吸收和利用效率存在显著差异,实生苗的干重、铵态氮吸收量、铵态氮吸收效率和氮效率均可作为枇杷氮高效种质评价和筛选指标。

We used the seedings of 22 wild loquat(Eriobotrya japonica Lindl.)germplasm from Guizhou Karst area as the test materials in the experiment,and the method of soil culture and nutrient solution culture experiment in this study.The plant height,and dry weight,nitrogen content,absorption amount and uptake efficiency of NH+4-N,nitrogen use efficiency,maximum uptake rate(Imax)of NH+4,the Michaelis constant value(Km),the flow rate of NH+4 into root(α)of 22 wild loquat germplasm seedlings under different NH+4-N levels were tested.The difference,interaction and correlation between the above indexes were analyzed and evaluated,and nutrition efficiency type of different wild loquat germplasm was divided.The results showed that:(1)the dry weight of seedlings,nitrogen absorption amount and nitrogen efficiency in different germplasm and NH+4-N levels were significantly different.The coefficient variation(CV)of seedlings'dry weight,nitrogen content,absorption amount and uptake efficiency of NH+4-N,and nitrogen efficiency were 21.09%and 16.87%,17.06%and 20.00%,36.67%and 40.21%,36.71%and 40.24%,21.05%and 19.21%,respectively among 22 wild loquat germplasm seedlings.The difference of NH+4 absorption kinetic parameters among different wild loquat germplasm were very obvious.The CV of Imax,Km andαunder high nitrogen and low nitrogen levels were 44.64%and 60.00%,73.53%and 81.48%,89.58%and 109.18%,respectively.(2)Among all the above indicators,the differences and interactions in different germplasm and two NH+4-N levels were extremely significant(P<0.01),the dry weight of seedlings,nitrogen content,absorption amount and uptake efficiency of NH+4-N,nitrogen efficiency,Imax andαof NH+4 all had extremely significantly positive correlation of 22 wild loquat germplasm,while the Km was extremely significantly negative correlation to above indexes.Under high nitrogen and low nitrogen levels,the direct path coefficient of NH+4-N absorption efficiency to nitrogen efficiency was the largest(1.805 and 1.523),and the direct contribution was also the most.(3)Through the above filter,22 wild loquat germplasm were classified into four nitrogen efficiency types:efficient under high nitrogen and low nitrogen,efficient under high nitrogen,efficient under low nitrogen and inefficient under high nitrogen and low nitrogen.There were 7,4,2 and 9 germplasm,respectively.The studies showed that the different of uptake and use efficiency for ammonium nitrogen among 22 wild loquat germplasm of Guizhou Karst area were significantly different.The dry weight of seedlings,absorption amount and uptake efficiency of NH+4-N,and nitrogen efficiency can be used as evaluation and filter indexes of nitrogen-efficient loquat germplasm.