Spring Nitrogen Uptake, Use Efficiency, and Partitioning for Growth in Iris germanica ‘Immortality’
Spring Nitrogen Uptake, Use Efficiency, and Partitioning for Growth in Iris germanica ‘Immortality’
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DOI：
10.21273/hortsci.51.5.563
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发表时间：
2016-05
期刊：
影响因子：
1.9
通讯作者：
Xiaojie Zhao;G. Bi;R. Harkess;J. Varco;E. Blythe
中科院分区：
文献类型：
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作者：
Xiaojie Zhao;G. Bi;R. Harkess;J. Varco;E. Blythe
研究了春季施氮对长生不老（iris germanica L.）高须鸢尾氮素吸收和生长性能的影响。2013年春季，采用改良的霍格兰（Hoagland）溶液施肥，每周两次，连续施肥6周，在容器种植的鸢尾植物中分别施用0、5、10、15或20 mM的NH4 NO3氮。施氮量的增加增加了株高、总干重和氮含量。全氮含量与植株总重密切相关。氮在不同组织中的分配趋势与水分的分配趋势相似。在叶片、根和根茎中，施氮量的增加增加了氮素吸收，降低了碳氮比（C/N）。叶片是氮素的主要吸收源。随着氮供给的增加，叶片中DW积累量增加，而根和根茎中DW积累量不变。说明增加施氮量对春季叶片生长的促进作用更大。氮素吸收效率（NupE）与施氮量的增加呈二次关系，且以10 mM施氮量最高，说明10 mM施氮量是本研究提高氮素吸收效率的最佳施氮量。鸢尾（德国鸢尾）是鸢尾科多年生植物。数以百计的结核虹膜杂交品种，从乌黑的黑色到闪闪发光的白色，每种颜色都有。鸢尾是一种受欢迎的园林植物，具有切花作物的潜力。在春季，鸢尾芽的大量生长需要充足的内源和外源养分供应。通常，建议在早春和春花之后施肥，以种植结核鸢尾（Lockatell and Spoon, 2011）。然而，关于施氮量如何影响油菜春季氮素吸收和利用效率的信息有限。氮在植物生长发育中起着重要作用。氮供应不足限制了植物的生长。增加施氮量影响植物生长（Bi et al., 2007）、叶片CO2同化（Cheng and Xia, 2004）以及其他养分的吸收和分配（Scagel et al., 2008, 2012）。然而，过量施氮会导致根区电导率升高，从而导致气体交换率、地上部DW和SPAD读数降低（Niu et al., 2011）。增加N供应可能会减少NupE，并导致更多的N径流到环境中（Syvertsen和Smith， 1996）。了解植物对氮的需求以及氮对植物产量和质量的影响对环境和作物生产都很重要（Bi et al., 2008; Dong et al., 2004; Lea-Cox et al., 2001; Scagel et al., 2012）。氮利用效率（NUE）是指每单位施氮量对植物生物量的固定干物质量（Marschner, 2012），它整合了两个组成部分：植物氮素利用效率（NUE）和植物吸收氮的利用效率（NUE） （Benincasa等人，2011）。NupE是指植物从供给的肥料中吸收氮的能力。nae证明了植物利用吸收的氮产生干生物量的能力。考虑到氮素在植物组织中的平均停留时间会影响氮素利用效率对增加氮素有效性的响应，氮素利用效率对施氮的氮素有效性表现出更动态的响应（Iversen et al., 2010）。生物量的碳氮比可能表明碳和氮源的相对可用性（Herms和Mattson， 1992）。碳占植物总重的50%，为植物提供结构基础（Agren, 2008），碳化合物为氨基酸同化提供能量和碳骨架。如果C供应不足，则会导致氮的吸收和同化减少（Zhang, 2009）。另一方面，氮供应不足减少了光合输出，如蔗糖和葡萄糖（Coruzzi和Zhou， 2001）。通过控制施氮量，可以调节作物碳氮比，提高产量和品质。本研究旨在探讨不同施氮量对春小麦植株生长、氮素浓度、含量、分配和碳氮比的影响，并评价施氮量对春小麦氮素吸收、氮素利用率、氮素e和氮素e的影响。材料与方法本研究在自然条件下进行。33 27# N，长。88 47# w)。2012年8月，将TB鸢尾花‘不朽’ （Schreiner ' s iris Gardens, Salem， OR）的根茎（平均直径4.7 cm，长度5.8 cm）每罐一根根茎盆栽到3.78 l（直径23 cm，高16 cm）的圆形塑料花盆中，里面装满了没有发源肥料的商业基材（Fafard生长混合物2；Sun Gro Horticulture, Agawam， MA）。2012年8月28日至9月28日，每周两次对植株施肥，植株接受400 mL含10 mM NH4NO3 N的改良Hoagland溶液（Hoagland and Arnon, 1950），为秋季生长提供基本养分供应。2013年3月25日，在春季氮处理开始前，收获5株植株，测定背景生物量和养分组成。从2013年3月25日至5月3日，对剩余植株每周施肥两次，每次施肥250 mL改良的霍格兰溶液，其中含有NH4 NO3中5种N浓度（0、5、10、15或20 mM N）中的一种。2013年3月、4月和5月的月平均气温分别为11.6、17.7和21.9℃。试验采用随机完全区组设计，共设5个区组。在每个街区，一组中的四株植物作为实验单位，接受五种氮浓度中的一种。2013年5月7日，随机抽取各氮素水平的5株进行破坏性收获，其余植株继续进行相同氮素水平NH4NO3处理，直至2013年9月。在2013年的生长季节，收集了花序数、花序茎长、株高和叶片SPAD读数（SPAD502；日本美能达相机公司（Minolta Camera Co.），是最早两个完全展开的叶片之一，用于测量SPAD读数）的数据。在2013年5月7日收获期间，记录了植株高度和扇叶数量。每棵植物被分为叶、根和根茎。所有样品在60℃下烘箱干燥至定重，并按组织类型记录DWs。所有的样品都被磨碎，通过一个40目筛，使用威利磨机（Thomas Scientific, Swedesboro， NJ）。2015年12月29日收稿。已接受2016年3月8日发表。密西西比农业和林业实验站的贡献12746. 本工作得到了密西西比州农林试验站、美国农业部国家粮食与农业研究所项目MIS-249120和mis -212050以及中国留学基金委的支持。提及商标、专有产品或供应商并不构成密西西比州立大学对该产品的保证或保证，也不意味着密西西比州立大学同意排除其他可能合适的产品或供应商。相应的作者。电子邮件:gbi@pss.msstate.edu。土壤科学vol . 51(5) 2016 . 563 bb0土壤管理，施肥，灌溉
This study investigated how spring nitrogen (N) application affects N uptake and growth performance in tall bearded (TB) iris ‘Immortality’ (Iris germanica L.). Container-grown iris plants were treated with 0, 5, 10, 15, or 20 mM N from NH4 NO3 through fertigation using a modified Hoagland’s solution twice a week for 6 weeks in Spring 2013. Increasing N rate increased plant height, total plant dry weight (DW), andN content. Total N content was closely related to total plant DW. The allocation of N to different tissues followed a similar trend as the allocation of DW. In leaves, roots, and rhizomes, increasing N rate increased N uptake and decreased carbon (C) to N ratio (C/N ratio). Leaves were the major sink for N derived from fertilizer (NDFF). As N supply increased, DW accumulation in leaves increased, whereas DW accumulation in roots and rhizomes was unchanged. This indicates increasing N rate contributed more to leaf growth in spring. Nitrogen uptake efficiency (NupE) had a quadratic relationship with increasing N rate and was highest in the 10 mM N treatment, which indicates 10 mM was the optimal N rate for improving NupE in this study. TB iris (Iris germanica) is a perennial plant belonging to the family Iridaceae. Hundreds of TB iris hybrids exist representing every color from jet black to sparkling white. TB iris is a popular garden plant with potential as a cut-flower crop. In spring, TB iris produces great amounts of shoot growth, which requires sufficient nutrient supply from both internal and external sources. Usually, fertilization in early spring and after spring flowering is recommended for growing TB iris (Lockatell and Spoon, 2011). However, limited information is available regarding how N rate affects spring N uptake and use efficiency in TB iris. Nitrogen plays an important role in plant growth and development. Insufficient N supply restricts plant growth. Increasing N application rate influences plant growth (Bi et al., 2007), leaf CO2 assimilation (Cheng and Xia, 2004), and uptake and allocation of other nutrients (Scagel et al., 2008, 2012). However, excessive N fertilizer application results in higher root zone electrical conductivity, which causes lower gas exchange rates, shoot DW, and SPAD readings (Niu et al., 2011). Increasing N supply may decrease NupE and lead to more N runoff to the environment (Syvertsen and Smith, 1996). Understanding a plant’s N requirement and the way N affects production and quality of plants is important to both the environment and crop production (Bi et al., 2008; Dong et al., 2004; Lea-Cox et al., 2001; Scagel et al., 2012). Nitrogen use efficiency (NUE) is estimated as the amount of dry matter fixed in plant biomass per unit ofN applied (Marschner, 2012), which integrates two components: plant NupE and use efficiency of absorbed N (NaUE) by the plant (Benincasa et al., 2011). NupE is the ability of the plant to take up N from supplied fertilizer. NaUE demonstrates the ability of the plant to use the absorbed N to produce dry biomass. Considering mean residence time of N in plant tissue affected NUE responses to increasing N availability, NupE showed a more dynamic response to N availability from applied N (Iversen et al., 2010). C/N ratio of biomass may indicate relative availability of C and N sources (Herms and Mattson, 1992). Carbon constitutes 50% of plant DW and provides the structural basis for plants (Agren, 2008) and C compounds provide both energy and the C skeletons for amino acid assimilation. If C supply is insufficient, it will cause decreased N uptake and assimilation (Zhang, 2009). On the other hand, insufficient N supply reduces photosynthetic output, such as, sucrose and glucose (Coruzzi and Zhou, 2001). By controlling N application, C/N ratios can be adjusted in crops to enhance yield and quality. The objectives of this study were to investigate influences of N rate on plant growth, N concentration, content, allocation, and C/N ratio, and to evaluate the effects of increasing N rate on N uptake, NUE, NupE, and NaUE during the spring growth period. Materials and Methods This study was conducted under natural conditions in Starkville, MS (lat. 33 27# N, long. 88 47# W). In Aug. 2012, rhizomes (average caliper = 4.7 cm and length = 5.8 cm) of TB iris ‘Immortality’ (Schreiner’s Iris Gardens, Salem, OR) were potted one rhizome per pot into 3.78-L (23 cm diameter; 16 cm height) round plastic pots filled with commercial substrate with no starter fertilizer (Fafard growing mix 2; Sun Gro Horticulture, Agawam, MA). Fertigation was applied to plants twice per week from 28 Aug. to 28 Sept. in 2012 with plants receiving 400 mL of modified Hoagland’s solution (Hoagland and Arnon, 1950) containing 10 mM N from NH4NO3 to provide basic nutrient supply for fall growth. On 25 Mar. 2013, before the start of spring N treatments, five plants were harvested for background biomass and nutrient composition. Remaining plants were fertigated twice per week from 25 Mar. to 3 May 2013 with 250 mL of modified Hoagland’s solution containing one of five N concentrations (0, 5, 10, 15, or 20 mM N) from NH4 NO3. The monthly average air temperature was 11.6, 17.7, and 21.9 C in Mar., Apr., and May 2013, respectively. The experiment was arranged as a randomized complete block design with five blocks. In each block, four plants in one group was an experimental unit receiving one of five N rates. Five plants from each N rate were randomly selected and destructively harvested on 7 May 2013 and the remaining plants were continually treated with the same N rate treatments from NH4NO3 until Sept. 2013. During the 2013 growing season, number of inflorescences, inflorescence stem length, plant height, and leaf SPAD reading (SPAD502; Minolta Camera Co., Japan, one of the first two fully expended leaves was selected to measure SPAD reading) data were collected. During harvesting on 7 May 2013, plant height and number of fans were recorded. Each plant was divided into leaves, roots, and rhizomes. All samples were oven dried at 60 C until constant weight and DWs were recorded by tissue type. All samples were ground to pass a 40-mesh sieve using a Wiley Mill (Thomas Scientific, Swedesboro, NJ). Received for publication 29 Dec. 2015. Accepted for publication 8 Mar. 2016. Contribution of the Mississippi Agricultural and Forestry Experiment Station Journal article no. 12746. This work was supported by the Mississippi Agriculture and Forestry Experiment Station, the USDA National Institute of Food and Agriculture Hatch projects MIS-249120 andMIS-212050, and the China Scholarship Council. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by Mississippi State University and does not imply its approval to the exclusion of other products or vendors that also may be suitable. Corresponding author. E-mail: gbi@pss.msstate.edu. HORTSCIENCE VOL. 51(5) MAY 2016 563 | SOIL MANAGEMENT, FERTILIZATION, AND IRRIGATION