| 温度和供氮形态对龙眼吸收氮素动力学的影响 |
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| 引用本文： | 朱陆伟,张智钧,白翠华,姚丽贤.温度和供氮形态对龙眼吸收氮素动力学的影响[J].热带作物学报,2022,43(2):337-345. |
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| 作者姓名： | 朱陆伟 张智钧 白翠华 姚丽贤 |
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| 作者单位： | 华南农业大学资源环境学院,广东广州 510640 |
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| 基金项目： | 财政部和农业农村部国家现代农业产业技术体系建设专项(No.CARS-32)。 |
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| 摘 要： | 研究龙眼幼苗在不同温度（10、15、20、25、30、35℃）和不同氮营养（硝态氮、3/4硝态氮+1/4铵态氮、1/2硝态氮+1/2铵态氮、1/4硝态氮+3/4铵态氮、铵态氮）供应条件下吸收氮素的动力学特征,比较龙眼吸氮能力变化,并探讨龙眼对氮形态的偏好性,为龙眼不同季节（物候期）选择适用氮肥形态提供依据。结果显示,温度和供氮形态对龙眼吸氮能力有显著影响（P<0.05）。在中低温度（10~25℃）等量供应硝态氮和铵态氮条件下,龙眼根系吸收氮素（硝态氮和铵态氮之和）的最大吸收速率（Imax）最高或较高,而亲和力（Am）和离子吸收补偿点（Cmin）则随温度和氮形态变化不大,故此时龙眼吸氮能力强。在高温（30℃）且仅供应铵态氮时,根系具有最高Imax和Am,同时Cmin最低,最有利于龙眼吸氮。在极端高温（35℃）时将铵态氮和硝态氮以3∶1的比例配合供应,则Imax最高,Am较高且Cmin较低,有利龙眼对氮素的吸收。另外,等量硝态氮和铵态氮共存条件下,龙眼在低温（10~15℃）时吸收铵态氮的Imax更高、Am更强而且Cmin更低,明显偏好铵态氮;在中高温（20~35℃）时吸收硝态氮的Imax更高,但Am更弱且Cmin更高,对氮形态的偏好性不明显。对照华南龙眼生长物候期,建议在龙眼秋梢生长期施用铵态氮为主、硝态氮为辅;在花前至小果期可以1∶1的比例施用硝态氮和铵态氮;在果实膨大期,可全部施用铵态氮或以3∶1的比例施入铵态氮和硝态氮。
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| 关 键 词： | 龙眼 物候期 硝态氮 铵态氮 吸收动力学 |
| 收稿时间： | 2021-07-20 |
Nitrogen Uptake Dynamics for Longan as Affected by Temperature and Nitrogen Form |
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| ZHU Luwei,ZHANG Zhijun,BAI Cuihua,YAO Lixian.Nitrogen Uptake Dynamics for Longan as Affected by Temperature and Nitrogen Form[J].Chinese Journal of Tropical Crops,2022,43(2):337-345. |
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| Authors: | ZHU Luwei ZHANG Zhijun BAI Cuihua YAO Lixian |
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| Affiliation: | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China |
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| Abstract: | Longan (Dimocarpus longan Lour.), a perennial fruit tree grown in tropical and subtropical areas, is subjected to great variation of temperature during a growth period. Temperature mediates the capability of plant root to absorb nutrients from the growth media. Generally, nitrogen (N) is the most-demanded element for most of the higher plants, and preference to N form is normally observed. Herein, N adsorption experiment with longan seedlings was conducted to investigate nitrogen (N) uptake dynamics affected by temperature (10, 15, 20, 25, 30 and 35℃) and N form (nitrate, 3/4 nitrate+1/4 ammonium, 1/2 nitrate+1/2 ammonium, 1/4 nitrate+3/4 ammonium, and ammonium), with the objective to select suitable N source for longan growth with the seasons (phenophases). The N consumption formulas in nutrient solutions were fitted to calculate N uptake dynamics by longan roots, and N absorption capability was compared as temperature and N form varied. Further, the preference to N form for longan was examined as well. N uptake by longan was significantly influenced by both temperature and N form (P<0.05). When equal amount of nitrate and ammonium was supplied at low to medium temperature (10-25℃), longan roots took up N (the sum of nitrate and ammonium) with the highest or higher maximum adsorption rate (Imax), however, the affinity to N (Am) for longan roots and the ion adsorption compensation point (Cmin) did not vary considerably, leading to a powerful adsorptive capacity for N by longan roots. While the temperature rose to high level (30℃) and ammonium was solely applied, the peak values of both Imax and Am and the bottom Cmin were simultaneously observed, which facilitated N uptake by longan roots. If ammonium and nitrate were amended with the ratio of 3 : 1 at extremely high temperature (35℃), longan roots took up more N with the upmost Imax, higher Am and lower Cmin. In addition, while the same levels of nitrate and ammonium were fed, longan roots took up ammonium with higher Imax, stronger Am and lower Cmin, suggesting preference to ammonium at low temperature (10-15℃). However, the root adsorbed nitrate with higher Imax, but weaker Am and higher Cmin at medium to high temperature (20-35℃), indicating no preference to N form. Based on the phenophase of longan grown in South China, it is suggested that N source with the majority of ammonium and minor nitrate facilitates N uptake by longan during the growth of the autumn shoot. Nitrate and ammonium are recommended to be used with the ratio of 1∶1 to enhance N adsorption during the period before anthesis to fruitlet development. Ammonium or the combination of ammonium and nitrate with the ratio of 3∶1 is proposed during fruit swelling stage in longan. |
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| Keywords: | longan phenophase nitrate ammonium uptake dynamics |
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