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氮磷添加对香樟容器苗营养元素化学计量特征的影响

Effects of nitrogen and phosphorus addition on the stoichiometric characteristics of nitrogen, phosphorus, and potassium in Cinnamomum camphora container seedlings

  • 摘要: 为探讨氮磷添加对香樟容器苗营养元素(氮、磷、钾)化学计量特征的影响,以1年生香樟容器苗为试验材料,采用指数施肥法,对香樟容器苗进行低氮、中氮、高氮、磷、低氮+磷、中氮 + 磷、高氮 + 磷等施肥处理,以不施肥为CK。在幼苗停止生长后,测定其根、茎、叶生物量和营养元素(氮、磷、钾)的化学计量特征。结果表明:单施P处理下根的生物量达到最大值,为1.857 g/株,在N3下的茎、叶和总生物量显著大于其他处理;N3、N2P和N3P处理下香樟容器苗根氮含量显著高于其他处理,分别为23.83 mg/g、24.712 mg/g和24.876 mg/g;N2P为茎中氮含量的最高处理(15.035 mg/g);在叶中,除单施磷肥外,其他处理的氮含量均显著高于CK,其中N3和N2P处理的叶氮含量最高。单独施磷肥显著地提高了香樟容器苗各器官的磷含量,与CK呈显著差异(P<0.05),而单施氮肥和氮磷配施对苗木各器官磷含量的影响则不大。氮磷配施显著增加了香樟容器苗叶片的N/P,其中N3P处理叶片的N/P显著高于其他处理,为4.67;在根中N/P较高的处理是N2P和N3P,分别为6.18和6.16;N2P为茎中N/P最高的处理,为4.27。整体上看,N2P和N3P更有利于增加香樟容器苗根茎叶中N/P值。施肥对于香樟容器苗地下部分钾含量增加的影响不明显,主要集中在地上部分,尤其是叶片,且氮磷配施对于香樟容器苗叶片钾含量的促进作用最大。N2,N3和N2P处理下满足N/K>2.1且 K/P<3.4,香樟容器苗根部受到了钾的限制。因此,限制香樟容器苗的生长因素为氮限制,施氮或氮磷配施能显著增加苗木生物量,改变其各器官的N/P,缓解其氮限制情况。

     

    Abstract: To explore the effects of nitrogen (N) and phosphorus (P) addition on the stoichiometric characteristics of nutrient elements (N, P, K) in container-grown Cinnamomum camphora seedlings, one-year-old container-grown Cinnamomum camphora seedlings were used as experimental materials. An exponential fertilization method was adopted, with fertilization treatments including low N (N1), medium N (N2), high N (N3), P alone (P), low N+P (N1P), medium N+P (N2P), and high N+P (N3P), using no fertilization as the control (CK). After the seedlings ceased growth, the biomass and stoichiometric characteristics of nutrient elements (N, P, K) in roots, stems, and leaves were determined.The results showed that the root biomass reached the maximum value of 1.857 g/plant under the P-only treatment, while the stem biomass, leaf biomass, and total biomass under N3 were significantly higher than those under other treatments. The root N contents of container-grown Cinnamomum camphora seedlings under N3, N2P, and N3P treatments were significantly higher than those under other treatments, being 23.83 mg/g, 24.712 mg/g, and 24.876 mg/g, respectively. N2P was the treatment with the highest stem N content (15.035 mg/g). In leaves, except for the P-only treatment, the N contents of other treatments were significantly higher than that of CK, among which N3 and N2P treatments had the highest leaf N contents.Applying P alone significantly increased the P content in various organs of container-grown Cinnamomum camphora seedlings, showing a significant difference from CK (P<0.05), while applying N alone and combined N-P fertilization had little effect on the P content in various organs of the seedlings. Combined N-P fertilization significantly increased the leaf N/P ratio of container-grown Cinnamomum camphora seedlings, among which the leaf N/P ratio under N3P treatment was significantly higher than that under other treatments (4.67). In roots, the treatments with higher N/P ratios were N2P and N3P, being 6.18 and 6.16, respectively. N2P was the treatment with the highest stem N/P ratio (4.27). Overall, N2P and N3P treatments were more conducive to increasing the N/P ratios in roots, stems, and leaves of container-grown Cinnamomum camphora seedlings.Fertilization had no obvious effect on increasing the K content in the underground parts of container-grown Cinnamomum camphora seedlings, and the effect was mainly concentrated in the aboveground parts, especially leaves. Moreover, combined N-P fertilization had the greatest promoting effect on the leaf K content of container-grown Cinnamomum camphora seedlings. Under N2, N3, and N2P treatments, N/K>2.1 and K/P<3.4 were satisfied, indicating that the roots of container-grown Cinnamomum camphora seedlings were limited by K.Therefore, the limiting factor for the growth of container-grown Cinnamomum camphora seedlings is N limitation. Applying N alone or combined N-P fertilization can significantly increase seedling biomass, change the N/P ratios in various organs, and alleviate N limitation.

     

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