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人类活动使得大量的铅(Pb)进入土壤环境,Pb在土壤中累积不仅会抑制植物生长,还会被作物吸收通过食物链对人类健康构成威胁[1]. 有研究报道美国农田与欧洲牧场土壤中Pb最大值分别达到135 mg·kg−1和1090 mg·kg−1[2-3]. 作为农业大国,我国土壤Pb污染比例为1.5%,加强修复技术体系研究,保障生态环境与食品安全,已成为重大的现实需求[4]. 植物修复作为一种原位修复技术,具有广泛的适用性和环境友好等优点,其中植物提取能够利用植物对重金属的吸收并通过收获地上部生物质清除土壤中的重金属,尤其适合漫污染区的修复[5]. 已发现多种Pb超积累植物能从土壤中提取大量的Pb并转运至地上部[6]. 然而超积累植物在Pb污染土壤修复的实际应用受其生长速率,实用价值和适生范围的限制[7]. 因此,有研究者提出种植具备金属耐受性、高生物量、农艺技术纯熟的非食用经济作物来修复污染土壤,兼顾生态与经济价值,让时间成本不再成为植物修复的限制因素,满足可持续发展需要,这已成为植物修复研究领域关注的热点[8].
在当今世界能源短缺的背景下,油料作物可以作为工业、医药原料且能制备生物能源而具有极高的经济价值,将油料作物开发与Pb污染土壤植物修复相结合,能够弥补植物修复的不足并充分利用Pb污染土壤发展生物能源[9]. 有关单一油料作物在应对土壤Pb污染方面已多有研究,Adesodun等[10]发现向日葵不同生长阶段对Pb的吸收积累不同,生长4周时植株地上部Pb积累效率最高. 张守文等[11]研究了油菜对Pb的耐性与富集效应,认为油菜具备修复Pb污染土壤的潜力. 然而,不同栽培物种的植物对Pb的耐受与积累存在差异,有效的植物修复需要考虑污染区的栽培历史和种植条件,选择特定的修复作物并形成农民驱动的修复模式[12],受限于现有研究间因环境条件、金属水平、栽培时间等方面的不同,难以比较并筛选出对Pb具有耐受与积累能力的修复型作物.
鉴于此,本文以种植范围广泛的大豆、向日葵和油菜等3种油料作物为试材,以生长状况和光合能力表征耐受性,以植株中Pb浓度、Pb积累量、生物富集系数BCF及转运系数TF评价Pb积累能力,且为避免作物因生育期不同引起的Pb积累差异,采用土培盆栽试验研究不同浓度土壤Pb污染对3种油料作物早期生长阶段的耐受性和Pb积累能力并对含油率和籽实中Pb含量进行评价,为筛选修复型油料作物以提高土壤污染植物修复技术的经济性提供新思路.
三种油料作物对土壤Pb污染的耐受性与积累
Tolerance and accumulation of lead in three oil crops to lead pollution in soil
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摘要: 为了选取具有修复Pb污染土壤潜力的油料作物,采用盆栽实验考察了不同浓度Pb(100、250、500、1000 mg·kg−1) 处理下3种常见油料作物(大豆、向日葵和油菜)对Pb的耐受性和积累能力的差异,并对经济性进行评估. 3种油料作物生长、光合、Pb积累及含油率的结果显示,100 mg·kg−1 Pb对3种油料作物生长无影响. 在250—1000 mg·kg−1 Pb处理下大豆生长最好,其次是向日葵和油菜.随土壤中Pb浓度升高,Pb对3种油料作物的不利影响表现为,初始荧光F0呈现增加趋势而净光合速率Pn、潜在光合活性Fv/F0、PSII最大光化学量子产量QY_max呈现降低趋势. 另外,大豆光合参数变幅最小,反映其对Pb的耐受性强于向日葵和油菜. 3种油料作物对Pb的积累与Pb处理浓度显著相关,地上部Pb积累量均高于根,且大豆最高,向日葵次之,油菜最低. 所有Pb处理下,大豆籽实中含油率与对照相比无显著变化.大豆籽实中Pb含量低于向日葵和油菜,符合饲料卫生标准. 综上,基于比较3种油料作物在相同生长时期内,对Pb的耐受和积累能力以及经济价值实现的可能性,大豆可以被认为是修复Pb污染土壤的合适选择.Abstract: To select oil crops that have the potential for remediating Pb-contaminated soil, we investigated the differences in Pb tolerance and accumulation capacity of three commom oil crops (soybean, sunflower and rape) and evaluated their ecomonics by pot experiments under different concentrations of Pb treatments (100, 250, 500, 1000 mg·kg−1). Results of growth, photosynthesis, Pb accumulation and oil content of three oil crops showed that 100 mg·kg−1 Pb had no effect on the growth of three oil crops compared to the control. Treated with the concentration of Pb at range from 250 to 1000 mg·kg−1, soybean grew best, followed by sunflower and rape. With the increase of Pb concentration in soil, the adverse effect caused by Pb on photosynthesis of three oil crops was showed by the increase in the minimal fluorescence (F0) and the decrease in the net photosynthetic rate (Pn), potential photosynthetic activity (Fv/F0) and maximal photochemical efficiency of PSII (QY_max). In addition, photosynthetic parameters of soybean had the smallest variation, showing that it had the highest tolerance to Pb compared to sunflower and rape. The accumulation of Pb in three oil crops was significantly correlated to the concentration of Pb treatments. Pb accumulation in aboveground part of three oil crops was higher than that in roots, and soybean was the highest, followed by sunflower, and rape was the lowest. Under all concentrations of Pb treatments, the oil content of soybean seeds had no significant change compared to the control. The Pb content in seeds of soybean was lower than that of sunflower and rape, meeting the feed hygiene standards. In conclusion, soybean can be considered as an appropriate option for remediating Pb contaminated soil based on the comparison of Pb tolerance and accumulation capacity of three oil crops at the same growth stage, as well as the realization possibility of economic value.
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Key words:
- lead polluted soil /
- phytoextraction /
- oil crop /
- photosynthesis /
- lead accumulation
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表 1 Pb对3种油料作物根与地上部干重的影响
Table 1. Effects of Pb on dry weight of root and aboveground in three oil crops
处理组
Treatments大豆 Glycine max 向日葵Helianthus annuus Linn. 油菜 Brassica napus L. 根/g
Root地上部/g
Aboveground根/g
Root地上部/g
Aboveground根/g
Root地上部/g
AbovegroundCK 0.096±0.007b(100.0) 0.617±0.011b(100.0) 0.085±0.006b(100.0) 0.712±0.013a(100.0) 0.028±0.002a(100.0) 0.223±0.007a(100.0) 100 0.101±0.008b(105.2) 0.621±0.010b(100.6) 0.088±0.004b(103.5) 0.715±0.007a(100.4) 0.029±0.003a(103.6) 0.231±0.007a(103.6) 250 0.113±0.005a(117.7) 0.670±0.006a(108.6) 0.097±0.007a(114.1) 0.720±0.010a(101.1) 0.029±0.003a(103.6) 0.221±0.007a(99.1) 500 0.091±0.008b(94.8) 0.612±0.005b(99.2) 0.072±0.006c(84.7) 0.668±0.015b(93.8) 0.025±0.002a(89.3) 0.200±0.006b(89.7) 1000 0.073±0.005c(76.0) 0.546±0.020c(88.5) 0.058±0.009d(68.2) 0.625±0.006c(87.8) 0.019±0.001b(67.9) 0.170±0.005c(76.2) 注:数据为平均值±标准误差,括号中数字为与CK相比各处理组相对值,不同字母表示各处理组间差异显著(P<0.05).
Note: The data is denoted as mean±standard deviation, relative values of each treatment compared with CK are shown in parentheses, different letters represent significant differences between treatments (P <0.05).表 2 Pb对3种油料作物叶绿素荧光参数的影响
Table 2. Effects of Pb on chlorophyll fluorescence parameters of three oil crops
处理组
Treatments大豆 Glycine max 向日葵 Helianthus annuus Linn. 油菜 Brassica napus L. F0 Fv/F0 QY_max F0 Fv/F0 QY_max F0 Fv/F0 QY_max CK 1900.92±59.81c
(100.0)3.89±0.06a
(100.0)0.80±0.01a
(100.0)2156.49±68.69d
(100.0)3.94±0.14a
(100.0)0.80±0.01a
(100.0)3036.74±74.15d
(100.0)1.59±0.10a
(100.0)0.61±0.01a
(100.0)100 2072.75±13.31b
(109.0)3.81±0.22a
(97.9)0.79±0.02a
(98.8)2228.13±68.91d
(103.3)3.92±0.12a
(99.5)0.80±0.01a
(100.0)3022.76±56.74d
(99.5)1.71±0.06a
(107.5)0.63±0.01a
(103.3)250 2131.36±34.20b
(112.1)3.68±0.20a
(94.6)0.79±0.01a
(98.8)2540.80±104.88c
(117.8)3.04±0.11b
(77.2)0.75±0.01b
(93.8)3296.50±69.67c
(108.6)1.30±0.12b
(81.8)0.56±0.02b
(91.8)500 2156.31±72.14b
(113.4)3.28±0.05b
(84.3)0.77±0.02b
(96.3)2737.03±53.43b
(126.9)2.43±0.12c
(61.8)0.71±0.02c
(88.8)3564.75±56.86b
(117.4)0.99±0.05c
(62.3)0.49±0.01c
(80.3)1000 2283.05±92.24a
(120.1)2.72±0.08c
(69.9)0.73±0.03c
(91.3)2906.21±31.70a
(134.8)1.99±0.07d
(50.5)0.66±0.01d
(82.5)3695.74±14.46a
(121.7)0.86±0.02d
(54.1)0.46±0.01d
(75.4)注:数据为平均值±标准误差,括号中数字为与CK相比各处理组相对值,不同字母表示各处理组间差异显著(P<0.05).
Note: The data is denoted as mean±standard deviation, relative values of each treatment compared with CK are shown in parentheses, different letters represent significant differences between treatments (P <0.05).表 3 3种油料作物对Pb的吸收与积累
Table 3. Uptake and accumulation of Pb in three oil crops
油料作物
Oil crop处理组
Treatments铅浓度Pb/(mg·kg−1) 单株铅积累量/µg
Pb accumulation per plantBCF TF 根
Root地上部
Aboveground根
Root地上部
Aboveground大豆
Glycine max100 24.98±0.77d 16.99±0.34d 2.54±0.20d 10.55±0.39d 0.17±0.01a 0.68±0.02b 250 37.59±2.26c 28.62±1.12c 4.27±0.43c 19.19±0.68c 0.11±0.01b 0.76±0.04a 500 77.85±1.14b 43.96±0.81b 7.10±0.50b 26.89±0.61b 0.09±0.01c 0.56±0.01c 1000 116.52±2.33a 63.43±0.72a 8.50±0.45a 34.64±0.65a 0.06±0.00d 0.55±0.01c 向日葵
Helianthus annuus Linn.100 23.77±1.76d 17.71±0.35d 2.09±0.12d 12.66±0.14d 0.18±0.01a 0.75±0.06a 250 36.44±2.87c 20.32±0.84c 3.53±0.22c 14.48±0.26c 0.08±0.00b 0.56±0.05b 500 88.03±7.17b 23.31±0.35b 6.37±1.03b 15.57±0.57b 0.05±0.01c 0.27±0.02c 1000 172.61±4.48a 30.94±0.72a 10.07±1.42a 19.35±0.60a 0.03±0.01d 0.18±0.01d 油菜
Brassica napus L.100 12.17±0.49d 8.64±0.75d 0.36±0.06d 1.94±0.20d 0.08±0.01a 0.71±0.08a 250 25.84±1.51c 11.25±0.66c 0.74±0.10c 2.56±0.15c 0.04±0.01b 0.44±0.06b 500 44.45±2.01b 18.43±0.23b 1.13±0.14b 3.69±0.18b 0.04±0.01c 0.41±0.02b 1000 78.35±3.11a 33.55±1.61a 1.52±0.15a 5.72±0.50a 0.03±0.00d 0.43±0.01b 注:数据为平均值±标准误差,不同字母表示各处理组间差异显著(P<0.05).
Note: The data is denoted as mean±standard deviation, different letters represent significant differences between treatments (P<0.05). -
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