• ISSN 1008-505X
  • CN 11-3996/S
于波, 秦嗣军, 吕德国. 适量供锌明显提高平邑甜茶幼苗碳氮吸收和同化效率[J]. 植物营养与肥料学报, 2021, 27(1): 97-108. DOI: 10.11674/zwyf.20312
引用本文: 于波, 秦嗣军, 吕德国. 适量供锌明显提高平邑甜茶幼苗碳氮吸收和同化效率[J]. 植物营养与肥料学报, 2021, 27(1): 97-108. DOI: 10.11674/zwyf.20312
YU Bo, QIN Si-jun, LÜ De-guo. Zinc in suitable level improves absorption and assimilation efficiency of carbon and nitrogen of Malus hupehensis seedlings[J]. Journal of Plant Nutrition and Fertilizers, 2021, 27(1): 97-108. DOI: 10.11674/zwyf.20312
Citation: YU Bo, QIN Si-jun, LÜ De-guo. Zinc in suitable level improves absorption and assimilation efficiency of carbon and nitrogen of Malus hupehensis seedlings[J]. Journal of Plant Nutrition and Fertilizers, 2021, 27(1): 97-108. DOI: 10.11674/zwyf.20312

适量供锌明显提高平邑甜茶幼苗碳氮吸收和同化效率

Zinc in suitable level improves absorption and assimilation efficiency of carbon and nitrogen of Malus hupehensis seedlings

  • 摘要:
    目的 氮素利用率低严重制约我国果树产业的可持续发展。通过研究不同供锌水平对苹果砧木平邑甜茶幼苗生长、光合作用、13C同化与分配和15N吸收、利用与分配的影响,探究锌对苹果氮素吸收利用的影响机制,为苹果生产中氮肥利用率的提高提供理论参考。
    方法 以苹果砧木平邑甜茶幼苗为试材进行砂培试验,试验周期为30天。设置Zn0、Zn2、Zn4、Zn8、Zn16 (分别相当于0、2.0、4.0、8.0、16.0 μmol/L Zn2+) 5个锌浓度处理,每3天更换一次营养液,每次向营养液中加入Ca (15NO3)2 0.01 g,共计加入0.1 g。正式处理25天后进行13C标记,于13C标记后24 、48 和96 h取样,测定各器官13C丰度。另于正式处理第30天取样,测定幼苗各器官生物量、根系形态、光合特性、碳氮代谢相关酶活性、各器官锌含量以及各器官含氮量、15N丰度。
    结果 5个处理中,Zn4处理幼苗各器官生物量与根系活力最高,根系形态指标 (根系长度、根系总表面积与根尖数) 最优。叶片净光合速率 (Pn)、气孔导度 (gs)、PSⅡ最大光化学效率 (Fv/Fm)、二磷酸核酮糖羧化酶(Rubisco)、硝酸还原酶(NR)及蔗糖磷酸合成酶(SPS)活性随供锌水平的提高呈先升高后降低的趋势,均在Zn4处理下达到最大,其值分别为15.21 μmol/(m2·s)、184.12 μmol/(m2·s)、0.839、8.4 μmol/(g·min)、103.25 μg/(g·h)和96.6 mg/(g·h);在Zn0处理最低,其值仅为Zn4处理的0.65、0.71、0.92、0.51、0.60和0.52倍。各器官锌含量均表现为Zn16 > Zn8> Zn4 > Zn2 > Zn0。同位素示踪结果表明,随着供锌水平的提高,幼苗整株13C积累量、15N吸收量以及15N利用率表现为先升高后降低,均在Zn4处理下达到最高,其值分别为1.95 mg、0.57 mg和15.8%。不同供锌水平对幼苗13C与15N分配率也有一定影响。其中,Zn4处理下根系13C分配率与叶15N分配率最高,分别为Zn0处理的1.53和1.18倍。
    结论 供锌不足与过量均抑制幼苗对氮素的吸收利用。而适宜供锌一方面通过改善叶片的光合作用,提高了叶片碳代谢相关酶活性,加强了叶片对碳的固定;提高了根系对光合产物的竞争力,加强了叶片光合同化物向根系的运输,促进根系生长发育的同时,改善了根系形态,提高了根系活力,进而增强了幼苗对氮素的吸收。另一方面,促进了氮素由根系向叶片的运输,同时提高了叶片硝酸还原酶活性,提高了幼苗对氮素的同化利用能力,进而促进了幼苗对氮素的吸收。因此,适宜锌营养可以有效提高幼苗的碳、氮吸收和同化效率。

     

    Abstract:
    Objectives Nitrogen nutrition is one of restrictions for efficient fruit production. The photosynthetic characteristics and the absorption, utilization of C and N of Malus hupehensis seedlings were studied under different zinc supply levels, aiming to find an effective way for improving nitrogen nutrition.
    Methods 15N and 13C tracer technique was used in a sand culture experiment in which Malus hupehensis seedlings were watered with a nutrient solution containing 0.01 g of Ca (15NO3)2. The Zn2+ treatment levels in the nutrient solution included 0, 2.0, 4.0, 8.0, 16.0 μmol/L. The nutrition solution was replaced every other three days, and after the seedlings grew for 25 days, then 0.2 g/seedling of Ba13CO3 (13C abundance was 98%) was added in each pot of the nutrient solution, and the samples were taken at the 24, 48 and 96 hours afterward to determine the 13C abundance of each organ. After 30 days, treatment, the seedlings were harvested, and dry mass, root morphology, photosynthetic characteristics, key enzyme activity, nitrogen content and 15N abundance in each organ were measured.
    Results Among the five Zn treatments, Zn2+ of 4.0 μmol/L treatment had the highest biomass and root activity, and the highest root morphological indexes (root length, root surface area and root tip number). The net photosynthetic rate (Pn), stomatal conductance (gs), maximum photochemical efficiency of PSⅡ (Fv/Fm), Rubisco, NR and SPS enzyme activities in all the five treatments were increased first and then decreased with the increase of Zn supply level, all of the maximum values were appeared under 4.0 μmol/L treatment, with the values of 15.21 μmol/(m2·s), 184.12 μmol/(m2·s), 0.839, 8.4 μmol/(g·min), 103.25 μg/(g·h), 96.6 mg/(g·h) respectively, and the lowest values were all appeared in CK treatment, which were 0.65, 0.71, 0.92, 0.51, 0.60 and 0.52 times of those in 4.0 μmol/L treatment. The Zn content of all organs increased with the increase of the Zn supply level, and reached the maximum value under treatment of Zn2+ 16.0 μmol/L. With the increase of Zn supply, 13C accumulation, total nitrogen, 15N uptake and 15N utilization efficiency of the whole plant increased first and then decreased, all the highest values of these indexes were obtained in treatment of Zn2+ 4.0 μmol/L, with the values of 1.95 mg, 59.5 mg, 0.57 mg and 15.8%, respectively. The distribution rates of 13C and 15N were also affected by Zn levels. Among them, both the distribution rate of 13C in roots and that of 15N in leaves was the highest in treatment of Zn2+ 4.0 μmol/L, which were 1.53 and 1.18 times of those in CK treatment, respectively.
    Conclusions Both insufficient and excessive Zn supply will inhibit the absorption and utilization of N by seedlings. On one hand, the suitable Zn supply can improve the photosynthesis of leaves, increase the activities of carbon metabolism related enzymes, strengthen the carbon fixation of leaves, improve the competitiveness of root system for photosynthetic products, strengthen the transportation of photosynthetic substances from leaves to roots, promote the growth and development of root system, improve the root morphology and root activity, and then enhance the nitrogen content of seedlings absorption. On the other hand, it promotes the transport of nitrogen from root to leaf, and increases the nitrate reductase activity of leaves, and enhances the assimilation and utilization ability of nitrogen by seedlings, which further promotes the absorption of nitrogen by seedlings. Therefore, suitable zinc supply will coordinately promote the absorption and assimilation of carbon and nitrogen of seedlings, and benefit the growth of seedlings.

     

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