4种梨实生苗硝态氮和铵态氮利用特性研究

为探讨不同梨实生苗对硝态氮和铵态氮的利用特性,以一年生杜梨、豆梨、川梨、木梨为试验材料,采用¹⁵NH₄NO₃和$NH_{4}^{15}$NO₃分别标记的方法,研究不同氮素形态对4种梨实生苗生长发育、根系形态及氮素吸收的影响。结果表明,木梨的地上部干重和总干重均最大,分别为20.56和29.21 g,其次是川梨和豆梨,杜梨最小。川梨根系干重最大,为8.80 g,其次是木梨,二者均显著高于豆梨和杜梨。根系总表面积、总根长、根尖数均以川梨最大,杜梨最小;根系活力以木梨最大,为2.04 mg·g^-1·h^-1,杜梨最小。4种实生苗标记硝态氮处理各器官吸收分配到的¹⁵N量对该器官全氮量的贡献(Ndff)均高于标记铵态氮处理;不管是标记硝态氮还是铵态氮,¹⁵N分配率均以叶最高,其次是根和茎。4种实生苗对硝态氮的利用率均高于铵态氮,其中木梨对硝态氮的利用率最高,为16.37%,且显著高于其他3种实生苗;川梨对铵态氮的利用率最高,为7.92%,但与木梨差异不显著,显著高于杜梨和豆梨。本研究为不同梨实生苗的氮素吸收特性和氮素营养管理的深入研究提供了科学依据。

Utilization Characteristics of$NO^{-}_{3}-^{15}$N and $NH^{+}_{4}-{15}$N for Four Pear Seedlings

To explore the utilization characteristics of nitrate and ammonium nitrogen in different pear seedlings, four kinds of one-year-old pear seedlings P. betulifolia Bge., P. calleryana Dcne., P. pashia D. Don., P. xerophila Yü] were used to study the characteristics of growth, root morphology, and absorption and distribution of nitrogen labeled $NH_{4}^{15}$NO₃ and ¹⁵NH₄NO₃. The results were as follows: the dry weight of above ground and total dry weight of P. xerophila Yü were the highest, and the value were 20.56 g and 29.21 g, followed by P. pashia D. Don. and P. calleryana Dcne, the lowest was found in P. betulifolia Bge. The dry weight of root of P. pashia D. Don. was the highest (8.80 g), followed by P. xerophila Yü, and they were significantly higher than that in P. calleryana Dcne and P. betulifolia Bge. The highest root surface area, total root length and root tips were found in P. pashia D. Don., while the least appeared in P. betulifolia Bge. The highest root activity appeared in P. xerophila Yü (2.04 mg·g^-1h^-1), while the value in P. betulifolia Bge. was lowest. The Ndff value of $NO^{-}_{3}-^{15}$N in the four kinds of seedlings were higher than that of $NH^{+}_{4}-{15}$N. The ¹⁵N distribution rate was not affected by different nitrogen forms, and the highest value was found in leaves, followed by roots and stems. The N$NO^{-}_{3}-^{15}$N utilization efficiency of the four kinds of seedlings was higher than that of $NH^{+}_{4}-{15}$N. The highest ¹⁵NO₃-N utilization efficiency was found in P. xerophila Yü (16.37%), which was significantly higher than that of the other three seedlings. The highest ¹⁵NO₃-N utilization efficiency was found in P. pashia D. Don. (7.92%) with no significant difference when compared with P. xerophila Yü, but it was significantly higher than that in P. betulifolia Bge. and P. calleryana Dcne. Therefore, this study provide a scientific basis for further study on nitrogen utilization characteristics and nitrogen management of pear seedlings.