钼对新疆野苹果幼苗生长和氮吸收利用特性的影响

夏营; 曹洪建; 丁荔; 王龙; 姜颖霖; 田歌; 姜远茂

doi:10.19303/j.issn.1008-0384.2022.005.010

钼对新疆野苹果幼苗生长和氮吸收利用特性的影响

Effects of Molybdenum on Growth and Nitrogen Uptake/Utilization of Malus sieversii Seedlings

摘要

摘要:
目的研究钼对苹果砧木新疆野苹果幼苗生长和氮吸收利用特性的影响，为苹果生产中科学施钼，提高氮素利用率提供理论依据。
方法以新疆野苹果幼苗为试材，设置5个供钼水平：CK、M1、M2、M3、M4，相应为0.00、0.25、0.50、1.50、3.00 μmol·L⁻¹的H₂MoO₄·H₂O。运用¹⁵N示踪技术，研究不同供钼水平对¹⁵N利用率和各器官Ndff值（植株器官从肥料¹⁵N中吸收分配到的¹⁵N量对该器官全氮量的贡献率）的影响，同时测定不同钼含量对幼苗生长、根系形态及活力和叶片中硝酸还原酶活性的影响。
结果与CK相比，施钼显著提高了幼苗各器官的生物量和¹⁵N利用率，并且随着施钼水平的增加均表现为先升高后下降的趋势，至M2处理时均达到最大值，¹⁵N利用率相对于CK处理提高了123%。0.00~0.50 μmol·L⁻¹钼水平下，新疆野苹果根系长度、表面积及根尖数均显著增加，叶片中硝酸还原酶（NR）活性和根系活力显著提高，各器官Ndff值也显著增加，而1.50~3.00 μmol·L⁻¹钼处理显著抑制了根系的生长，新疆野苹果幼苗根系长度、表面积、根尖数量均显著下降，叶片中NR活性及根系活力、各器官的Ndff值也表现出下降趋势，各指标均与M1处理差异不显著。
结论 0.50 μmol·L⁻¹的钼酸处理，一方面有利于植株生长和根系发生，增强对氮素的吸收；另一方面提高了硝酸还原酶活性，通过推进氮还原的进程促进了氮素的利用。因此，在此浓度钼酸处理下幼苗¹⁵N利用率最高。

Abstract:
Objectives Effects of molybdenum (Mo) on the growth and nitrogen uptake/utilization of Malus sieversii seedlings were studied for the cultivation and crop production improvements.
Methods M. sieversii seedlings were grown under 5 levels of Mo supply equivalent to 0.00 (CK), 0.25 (M1), 0.50 (M2), 1.50 (M3), and 3.00 μmol·L⁻¹ (M4) H₂MoO₄·H₂O. The ¹⁵N utilization and Ndff (i.e., rate of ¹⁵N absorbed by a plant organ from ¹⁵N in fertilizer to total nitrogen in the organ) were determined using the ¹⁵N labeled tracer method. The growth, root morphology, and nitrate reductase (NR) activity in leaves of the seedlings were monitored.
Results The Mo applications significantly altered the biomass and ¹⁵N utilization rate of seedlings in an increasing pattern with increasing Mo to peak at M2 (the ¹⁵N utilization rate was 123% of that of CK), then followed by a decline. From 0 to 0.5 μmol Mo·L⁻¹, the length, surface area, number of tips and activities of the seedling roots, the NR in the leaves, and the Ndff of all organs significantly increased. But further increasing Mo from 1.5 to 3.0 μmol·L⁻¹ caused significant decreases on all indicators to become not significantly different from those under the M1 treatment.
Conclusions By treating potato rootstocks with Mo at 0.5 μmol·L⁻¹, the seedling growth, root formation, and plant nitrogen absorption were enhanced. The seedling ¹⁵N utilization rate was maximized by the treatment that effectively promoted nitrogen reduction due to the increased nitrate reductase activity.

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