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硼是维管植物生长发育所必需的微量元素之一[1]。植物体内的硼主要以硼酸酯键的形式与鼠李半乳糖醇结合,在细胞壁的果胶中建立交联,从而决定着细胞壁的完整性和稳定性[2]。另外,硼在离子跨膜运输、细胞分裂和伸长、碳水化合物的运输、蛋白质和核酸的代谢、花粉的萌发和花粉管的伸长等方面有广泛的影响[3]。缺硼植物的营养生长(叶片卷曲、顶稍枯死、根尖坏死)和生殖生长(蕾而不花、花而不实)均受限制[4]。最近的研究发现,缺硼条件下松树木材密度、管胞直径、细胞壁厚度和木质素含量减小,从而对木材的加工利用有重要影响[5]。北欧天然林区年度硼输出大于硼输入,土壤有效硼流失严重[6]。爱沙尼亚杂交杨(P. tremula L. × P. tremuloides Michx)人工林的土壤有效硼含量在10年时间内下降了48%[7]。国内研究发现,缺硼导致桉树(Eucalyptus L. Herit)红叶枯梢病、柑橘(Citrus reticulata Blanco)畸形果等症状,影响油橄榄(Olea europaea L.)等的产量[8]。杨树(Populus L.)具有生长迅速、繁殖容易、适应性强等特点,是重要的工业原料林[9-10]。江西鄱阳、抚州及福建邵武等地的杨树苗圃以及湖北潜江杨树试验林曾出现缺硼症状[11]。可见,杨树人工林及其苗圃易缺硼,在经营培育中应采用基肥、追肥或叶面肥等方式施用硼肥。
高等植物将硼运输到所需部位有2种方式,即木质部运输和韧皮部运输;前者将根系吸收的硼经木质部运输,该过程依赖于蒸腾作用;后者将可溶性的有机硼(硼-糖/糖醇化合物)经韧皮部从植物体内的“硼库”运输到需要的组织细胞中[12]。植物长距离运输硼的主要通道是木质部,所以,木质部液流与硼的吸收和运输有较大的关系。韧皮部运输也称为再转运,其运输能力在物种间呈多态性,与植物体内游离糖醇的种类和含量有关;与常绿树种相比,落叶树种中硼的韧皮部运输能力较强[12]。最近,基于柑橘的研究表明,叶片中的硼可以与蔗糖形成复合物,进而伴随着蔗糖的运输从成熟叶片再分配到其它器官中[13]。杨树对硼的吸收能力、分配模式及韧皮部再转运能力尚不明确。因此,本研究拟通过控制条件下的室内试验,采用砂培新疆杨(Populus alba var. pyramidalis Bunge)为材料,在营养液中添加不同浓度的硼肥,比较分析新疆杨在不同硼水平下的吸收能力及其向不同部位的分配模式,并通过下部叶片饲喂富10B硼酸,研究杨树的韧皮部再转运能力,为杨树人工林的培育和经营提供参考。
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与正常硼浓度营养液(NB)相比,低硼浓度营养液(LB)导致植株株高、总干质量及根、茎、下部叶、上部叶等干质量显著下降,但根长差异不显著(表1)。与LB相比,LB + F可显著提高总干质量和根部干质量;对其它部位的干质量也有一定的促进作用,但差异不显著。NB + F与NB相比,各项数据均差异不显著。数据表明,施叶面硼肥可在一定程度上缓解根际硼亏缺对新疆杨生长的负面影响。
表 1 营养液硼浓度及叶面硼肥对新疆杨生长情况的影响
Table 1. Growth changesof P. alba var. pyramidalis to different boron fertilizer conditions
处理
Treatment根长/cm
Root length株高/cm
Plant height干质量Dry weight/(g·株−1) 根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves总干质量
TotalLB 12.38 ± 0.78 a 20.85 ± 2.95 b 0.40 ± 0.07 c 0.34 ± 0.10 b 0.39 ± 0.11 b 0.52 ± 0.14 b 1.65 ± 0.41 c LB + F 14.10 ± 2.30 a 18.80 ± 5.51 b 0.73 ± 0.06 b 0.40 ± 0.11 b 0.64 ± 0.22 ab 0.68 ± 0.20 ab 2.46 ± 0.50 b NB 12.00 ± 1.14 a 27.55 ± 3.51 a 0.92 ± 0.21 ab 0.79 ± 0.12 a 0.73 ± 0.18 a 0.93 ± 0.09 a 3.37 ± 0.48 a NB + F 17.68 ± 6.60 a 23.15 ± 2.12 ab 1.03 ± 0.20 a 0.62 ± 0.11 a 0.55 ± 0.16 ab 0.84 ± 0.27 a 3.04 ± 0.63 ab 注:LB,低硼浓度营养液;LB + F,LB + 叶面肥;NB,正常硼浓度营养液;NB + F,NB + 叶面肥。数据为平均值 ± 标准差,n = 4;不同小写字母表示不同处理间显著差异(P < 0.05)。下同
Notes: LB, low boron concentration in Hoagland solution; LB + F, LB + foliar-B fertilization; NB, normal boron concentration in Hoagland solution; NB + F, NB + foliar-B fertilization. Data shown are mean ± SD (n = 4). Different normal letters indicate statistical significance among different treatments at 0.05 level. The same below -
与NB相比,LB处理下新疆杨上部叶硼浓度显著下降,下部叶硼浓度差异不显著,根、茎硼浓度显著增加;根、茎、下部叶、上部叶的硼积累量均显著下降(表2)。LB处理下,上部叶的硼积累量占整株植物硼积累总量的29.9%,显著低于NB条件下的38.0%(P < 0.05)。与LB相比,LB + F可显著提高叶片硼浓度和硼积累量,但对根和茎的硼积累量影响不明显。NB + F与NB相比,除茎部硼浓度显著上升外,其它各项数据均差异不显著。
表 2 营养液硼浓度及叶面硼肥对新疆杨不同部位硼浓度和积累量的影响
Table 2. Effects of different boron fertilizer conditionson boron concentration and accumulation of P. alba var. pyramidalis
处理
Treatments硼浓度 Boron concentration/(mg·kg−1) 硼积累Boron accumulation/(μg·株−1) 根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leavesLB 54.3 ± 3.0 a 48.2 ± 1.9 a 96.1 ± 8.4 b 62.2 ± 6.9 c 22.7 ± 4.9 c 18.4 ± 2.8 b 41.4 ± 12.8 c 35.2 ± 3.4 b LB + F 44.0 ± 3.7 b 40.8 ± 0.9 ab 149.8 ± 15.7 a 135.7 ± 10.1 a 32.8 ± 0.7 bc 17.9 ± 4.4 b 109.7 ± 7.8 a 101.9 ± 16.0 a NB 41.9 ± 3.6 b 36.9 ± 8.9 b 104.3 ± 6.2 b 102.6 ± 4.2 b 38.0 ± 8.8 ab 30.9 ± 5.9 a 85.4 ± 9.7 ab 94.6 ± 8.9 a NB + F 39.4 ± 3.0 b 48.7 ± 2.4 a 90.5 ± 22.1 b 94.7 ± 15.1 b 44.6 ± 5.1 a 31.7 ± 5.6 a 55.9 ± 27.2 bc 89.3 ± 14.8 a -
与NB相比,LB处理下新疆杨上部叶和下部叶的10B浓度无显著变化,而11B浓度显著下降,根和茎的10B和11B浓度均显著上升(表3)。与LB相比,LB + F可显著提高上部叶和下部叶的10B浓度,但对根和茎的10B浓度影响不明显;11B浓度在上部叶中显著上升,在下部叶中无显著变化,在根和茎中显著下降。与NB相比,NB + F下部叶的10B浓度增加了81%,但标准差较大,差异不显著,茎10B浓度显著上升,根和上部叶10B浓度无明显变化;茎11B浓度显著上升,而下部叶和上部叶11B浓度显著下降。
表 3 营养液硼浓度及叶面硼肥对新疆杨不同部位10B和11B硼浓度的影响
Table 3. Effects of different boron fertilizer conditions on 10B and 11B concentration of P. alba var. pyramidalis
处理
Treatments10B浓度
Concentration/(mg·kg−1)11B浓度
Concentration/(mg·kg−1)根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper LeavesLB 13.2 ± 0.6 a 11.7 ± 0.3 a 28.9 ± 3.5 b 18.0 ± 2.2 b 41.1 ± 2.4 a 36.6 ± 1.6 a 67.2 ± 6.8 b 44.2 ± 5.3 c LB + F 13.2 ± 2.8 a 12.2 ± 1.3 a 86.6 ± 17.3 a 48.1 ± 4.8 a 30.8 ± 1.0 b 28.6 ± 0.8 b 63.2 ± 3.6 b 87.6 ± 5.4 a NB 9.4 ± 0.9 b 8.3 ± 1.9 b 23.1 ± 1.5 b 23.1 ± 0.6 b 32.5 ± 2.8 b 28.6 ± 7.0 b 81.2 ± 4.7 a 79.6 ± 3.6 a NB + F 9.0 ± 0.7 b 11.4 ± 0.5 a 41.8 ± 20.7 b 26.0 ± 10.3 b 30.4 ± 2.3 b 37.3 ± 1.8 a 48.7 ± 1.8 c 68.7 ± 4.9 b -
NB条件下,各部位的10B丰度约为22.4%;LB条件下,根和茎的10B丰度约为24.2%,叶片的10B丰度约为29.5%;均高于自然丰度19.78%(图1A)。与LB相比,LB + F处理下植株各部位的10B丰度均显著增加,表明叶面吸收的硼可以从下部成熟叶片转运到根、茎、上部幼嫩叶片等部位。与NB相比,NB + F处理的下部叶的10B丰度显著增加,而其它部位无显著变化。
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10Boff(来自于叶面肥的10B)占样品10B含量的百分比,在LB + F和NB + F下部叶中分别为42.2%和30.6%,均显著高于其它部位(图1B)。10Boff浓度和积累量呈相同的趋势(图1C、D):在LB + F的下部叶中均最高,其次是LB + F的上部叶,二者与其它部位及NB + F的各个部位均差异显著;LB + F的10Boff积累总量为81.3 μg·株−1,高于NB + F的10Boff积累量(12.7 μg·株−1)(图1D)。图2A表明:LB + F条件下,大部分10Boff被保留在下部叶片(61.99%),另有31.68%被分配给上部叶,5.27%被分配到根中,1.06%被分配到茎部。NB + F条件下,60.7%的10Boff被保留在下部叶片,22.3%被分配给上部叶,13.5%被分配到根中,3.5%被分配茎部(图2B)。
应用10B示踪技术研究杨树幼苗对叶面硼的吸收和分配
Study of Foliar Fertilizer-B Absorption and Distribution in Poplar Saplings Using 10B Tracer
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摘要:
目的 研究不同硼肥条件下杨树对硼肥的吸收、分配和再转运能力,为杨树人工林的培育和经营提供参考。 方法 采用新疆杨(Populus alba var. pyramidalis Bunge)为试验材料,进行温室控制条件下的砂培试验,在营养液中添加不同浓度硼酸,并通过下部成熟叶片饲喂富10B硼酸(H310BO3),记录杨树生长情况,测定各部位硼含量。 结果 (1)砂培条件下,降低营养液中硼浓度(LB),新疆杨生物量和硼积累量显著下降,上部叶片硼浓度显著下降,分配给幼嫩叶片的硼占植株硼积累总量的比例显著下降。(2)在LB的基础上饲喂叶面硼肥(LB + F),可补充上部叶片硼浓度,在一定程度上缓减植株生物量和硼积累量的变化;大部分从叶面肥中吸收的硼被保留在饲喂叶片中,还可被再转运到幼嫩叶片(31.68%)、根(5.27%)和茎(1.06%)。(3)在营养液硼浓度足量(NB)的基础上饲喂叶面硼肥(NB + F),茎部硼浓度显著上升,但对根、叶硼浓度和各部位生物量的影响不明显;与LB + F相比,NB + F从叶面肥中吸收的硼较少,仅为前者的15.6%。 结论 低硼胁迫导致新疆杨幼嫩叶片的硼分配减少,影响植株生长,成熟叶片吸收的叶面硼肥可再转运并分配给以幼嫩叶片为主的其它部位,通过施叶面硼肥可弥补根际硼亏缺对植株生长的影响。 Abstract:Objective The absorption, distribution and re-translocation of foliar boron fertilizer in poplar under different boron conditions were analyzed, in order to provide clues for the cultivation and management of poplar plantation. Method Populus alba var. pyramidalis Bunge saplings were sand cultured in greenhouse. Different concentrations of boric acid were added to the nutrient solution, and the lower mature leaves were fed with 10B-rich boric acid (H310BO3). The growth of poplar was recorded, and the boron content in different parts was determined. Result (1) Under sand culture condition with low boron concentration, the biomass and boron accumulation of plants decreased significantly, the boron concentration in upper leaves significantly decreased, and the proportion of boron allocated to young leaves significantly decreased also. (2) Application of foliar boron fertilizer (LB + F) could supplement the boron concentration in upper leaves, and reduce the changes of biomass and boron accumulation to a certain extent. Most of boron absorbed from foliar fertilizer was retained in the fertilized leaves, while 31.68%, 5.27% and 1.06% of absorbed foliar boron can be re-translocated to young leaves, roots, and stems. (3) In relative to normal boron concentration, application of foliar boron fertilizer (NB + F) could increase boron concentration in stem, but had no significant effect on boron concentration of roots and leaves and the biomass in different parts. Compared with LB + F, NB + F plant absorbed much less boron from foliar fertilizer, which was only 15.6% of the former. Conclusion Boron deficiency will result in a reduced boron allocation to young leaves in poplar, thus affects plant growth. The boron fertilizer absorbed by mature leaves could be re-translocated to other parts of the plant, especially the young leaves. The negative effect of rhizosphere boron deficiency on plant growth can be compensated by applying foliar boron fertilizer. -
表 1 营养液硼浓度及叶面硼肥对新疆杨生长情况的影响
Table 1. Growth changesof P. alba var. pyramidalis to different boron fertilizer conditions
处理
Treatment根长/cm
Root length株高/cm
Plant height干质量Dry weight/(g·株−1) 根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves总干质量
TotalLB 12.38 ± 0.78 a 20.85 ± 2.95 b 0.40 ± 0.07 c 0.34 ± 0.10 b 0.39 ± 0.11 b 0.52 ± 0.14 b 1.65 ± 0.41 c LB + F 14.10 ± 2.30 a 18.80 ± 5.51 b 0.73 ± 0.06 b 0.40 ± 0.11 b 0.64 ± 0.22 ab 0.68 ± 0.20 ab 2.46 ± 0.50 b NB 12.00 ± 1.14 a 27.55 ± 3.51 a 0.92 ± 0.21 ab 0.79 ± 0.12 a 0.73 ± 0.18 a 0.93 ± 0.09 a 3.37 ± 0.48 a NB + F 17.68 ± 6.60 a 23.15 ± 2.12 ab 1.03 ± 0.20 a 0.62 ± 0.11 a 0.55 ± 0.16 ab 0.84 ± 0.27 a 3.04 ± 0.63 ab 注:LB,低硼浓度营养液;LB + F,LB + 叶面肥;NB,正常硼浓度营养液;NB + F,NB + 叶面肥。数据为平均值 ± 标准差,n = 4;不同小写字母表示不同处理间显著差异(P < 0.05)。下同
Notes: LB, low boron concentration in Hoagland solution; LB + F, LB + foliar-B fertilization; NB, normal boron concentration in Hoagland solution; NB + F, NB + foliar-B fertilization. Data shown are mean ± SD (n = 4). Different normal letters indicate statistical significance among different treatments at 0.05 level. The same below表 2 营养液硼浓度及叶面硼肥对新疆杨不同部位硼浓度和积累量的影响
Table 2. Effects of different boron fertilizer conditionson boron concentration and accumulation of P. alba var. pyramidalis
处理
Treatments硼浓度 Boron concentration/(mg·kg−1) 硼积累Boron accumulation/(μg·株−1) 根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leavesLB 54.3 ± 3.0 a 48.2 ± 1.9 a 96.1 ± 8.4 b 62.2 ± 6.9 c 22.7 ± 4.9 c 18.4 ± 2.8 b 41.4 ± 12.8 c 35.2 ± 3.4 b LB + F 44.0 ± 3.7 b 40.8 ± 0.9 ab 149.8 ± 15.7 a 135.7 ± 10.1 a 32.8 ± 0.7 bc 17.9 ± 4.4 b 109.7 ± 7.8 a 101.9 ± 16.0 a NB 41.9 ± 3.6 b 36.9 ± 8.9 b 104.3 ± 6.2 b 102.6 ± 4.2 b 38.0 ± 8.8 ab 30.9 ± 5.9 a 85.4 ± 9.7 ab 94.6 ± 8.9 a NB + F 39.4 ± 3.0 b 48.7 ± 2.4 a 90.5 ± 22.1 b 94.7 ± 15.1 b 44.6 ± 5.1 a 31.7 ± 5.6 a 55.9 ± 27.2 bc 89.3 ± 14.8 a 表 3 营养液硼浓度及叶面硼肥对新疆杨不同部位10B和11B硼浓度的影响
Table 3. Effects of different boron fertilizer conditions on 10B and 11B concentration of P. alba var. pyramidalis
处理
Treatments10B浓度
Concentration/(mg·kg−1)11B浓度
Concentration/(mg·kg−1)根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper leaves根
Roots茎
Stems下部叶
Lower leaves上部叶
Upper LeavesLB 13.2 ± 0.6 a 11.7 ± 0.3 a 28.9 ± 3.5 b 18.0 ± 2.2 b 41.1 ± 2.4 a 36.6 ± 1.6 a 67.2 ± 6.8 b 44.2 ± 5.3 c LB + F 13.2 ± 2.8 a 12.2 ± 1.3 a 86.6 ± 17.3 a 48.1 ± 4.8 a 30.8 ± 1.0 b 28.6 ± 0.8 b 63.2 ± 3.6 b 87.6 ± 5.4 a NB 9.4 ± 0.9 b 8.3 ± 1.9 b 23.1 ± 1.5 b 23.1 ± 0.6 b 32.5 ± 2.8 b 28.6 ± 7.0 b 81.2 ± 4.7 a 79.6 ± 3.6 a NB + F 9.0 ± 0.7 b 11.4 ± 0.5 a 41.8 ± 20.7 b 26.0 ± 10.3 b 30.4 ± 2.3 b 37.3 ± 1.8 a 48.7 ± 1.8 c 68.7 ± 4.9 b -
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