氮(N)限制植物生产力,它的吸收和同化可能受氮源的调节,N同化酶,和N个同化基因。掌握氮素吸收和同化的调控机制是提高植物氮素利用效率(NUE)的关键途径。然而,尚不清楚这些因素如何相互作用以影响山核桃的生长过程。在这项研究中,增长,通过不同NH4/NO3-比例(0/0、0/100、25/75、50/50、75/25、100/0作为CK,分析了山核桃的养分吸收和氮同化特性,T1、T2、T3、T4和T5)。结果表明,T4和T5处理对生长有最佳的促进作用,山核桃的养分吸收和氮同化酶活性,显著增加了地上生物量,平均相对增长率(RGR),根区,根系活动,游离氨基酸(FAA)和总有机碳(TOC)浓度,硝酸还原酶(NR),亚硝酸还原酶(NiR),谷氨酰胺合成酶(GS),谷氨酸合酶(Fd-GOGAT和NADH-GOGAT),和谷氨酸脱氢酶(GDH)活性。根据qRT-PCR结果,大多数N同化基因在叶片中表达水平较高,在T1和T4处理下主要显著上调。相关分析表明,N同化酶与N同化基因之间不一定存在相关性。偏最小二乘路径模型(PLS-PM)分析结果表明,N同化基因可以通过调节N同化酶和养分来影响山核桃的生长。总之,我们建议75:25的NH4/NO3-比例更有利于提高山核桃的生长和NUE。同时,我们认为植物氮同化能力的测定应该是对氮浓度进行综合分析的结果,N同化酶及相关基因。
Nitrogen (N) limits plant productivity, and its uptake and assimilation may be regulated by N sources, N assimilating enzymes, and N assimilation genes. Mastering the regulatory mechanisms of N uptake and assimilation is a key way to improve plant nitrogen use efficiency (NUE). However, it is poorly known how these factors interact to influence the growth process of pecans. In this study, the growth, nutrient uptake and N assimilation characteristics of
pecan were analyzed by aeroponic cultivation at varying NH4 +/NO3 - ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that T4 and T5 treatments optimally promoted the growth, nutrient uptake and N assimilating enzyme activities of
pecan, which significantly increased aboveground biomass, average relative growth rate (RGR), root area, root activity, free amino acid (FAA) and total organic carbon (TOC) concentrations, nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (Fd-GOGAT and NADH-GOGAT), and glutamate dehydrogenase (GDH) activities. According to the qRT-PCR results, most of the N assimilation genes were expressed at higher levels in leaves and were mainly significantly up-regulated under T1 and T4 treatments. Correlation analysis showed that a correlation between N assimilating enzymes and N assimilating genes did not necessarily exist. The results of partial least squares path model (PLS-PM) analysis indicated that N assimilation genes could affect the growth of
pecan by regulating N assimilation enzymes and nutrients. In summary, we suggested that the NH4 +/NO3 - ratio of 75:25 was more beneficial to improve the growth and NUE of
pecan. Meanwhile, we believe that the determination of plant N assimilation capacity should be the result of a comprehensive analysis of N concentration, N assimilation enzymes and related genes.