ECOPHYSIOLOGICAL RESPONSE OF TAMARIX LAXA TO CADMIUM STRESS

doi:10.17521/cjpe.2007.0018

Abstract

Abstract:

Aims Excretion of salt by gland had been studied, but the response of salt glands to heavy metals was rarely explored. A hydroponic cultivation experiment was conducted in glasshouse with excretohalophyte to investigate: 1) if salt gland is able to excrete Cd²⁺ ions, 2) extent of Cd²⁺ tolerance for secretohalophyte, and 3) possible mechanisms by which the excretohalophyte is able to resist Cd²⁺ stress.

Methods Branches of Tamarix laxa plants were cut into 15 cm sections and propagated for 3 months. They were then transferred into hydroponic cultivation with a Hoagland's nutrient solution for 20 days and treated with 0, 10, 50, 200 and 500 μmol·L ^-1 Cd²⁺ for 2 weeks to determine the uptake and excretion of Cd²⁺.

Important findings There were no significant differences in the relative growth rate or water content of the plants between the treatment with 10 μmol·L ^-1 Cd²⁺ and the control. When Cd²⁺ levels exceeded 50 μmol·L ^-1, the shoots of T. laxa suffered toxicity. Cd²⁺ excretion through salt glands was detected in all Cd²⁺-added treatments, but the total amount was lower, although the amount of secreted Cd²⁺ from salt gland was increased with increasing of Cd²⁺ levels. Salt glands excreted Cd²⁺, but the secretion plays less important role in Cd²⁺ toxic resistance for excretohalophyte.

Key words: Tamarix laxa, cadmium, salt gland, excretion

DING Xiao-Dong, GAO Dong-Rui, FENG Gu. ECOPHYSIOLOGICAL RESPONSE OF TAMARIX LAXA TO CADMIUM STRESS[J]. Chin J Plant Ecol, 2007, 31(1): 145-149.

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Figures/Tables 4

References 18

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镉处理 Cd²⁺ treatment (μmol·L^-1)	症状 Symptom
镉处理 Cd²⁺ treatment (μmol·L^-1)	地上部分 Shoot	地下部分 Root
0	无症状 No symptom	无症状 No symptom
10	无症状 No symptom	根尖变大 Root tip enlarged
50	14 d开始泛黄不如原先翠绿 Yellowed and losing green after 14 d	根尖变大,根毛腐烂,由白变黑 Root tip enlarged,root hair rotted and changed from white to black
200	12 d出现黄尖现象 Chlorosis of shoot tip after 12 d	根毛腐烂,变黑 Root hair rotted,nigrescence
500	12 d发生枯萎现象 Withered after 12 d	根毛腐烂 Root hair rotted

镉处理 Cd²⁺ treatment (μmol·L^-1)	症状 Symptom
镉处理 Cd²⁺ treatment (μmol·L^-1)	地上部分 Shoot	地下部分 Root
0	无症状 No symptom	无症状 No symptom
10	无症状 No symptom	根尖变大 Root tip enlarged
50	14 d开始泛黄不如原先翠绿 Yellowed and losing green after 14 d	根尖变大,根毛腐烂,由白变黑 Root tip enlarged,root hair rotted and changed from white to black
200	12 d出现黄尖现象 Chlorosis of shoot tip after 12 d	根毛腐烂,变黑 Root hair rotted,nigrescence
500	12 d发生枯萎现象 Withered after 12 d	根毛腐烂 Root hair rotted

镉处理 Cd²⁺ treatment (μmol·L^-1)	14 d相对生长量 (%) Relative biomass after 14 d	含水率 Water content(%)
镉处理 Cd²⁺ treatment (μmol·L^-1)	14 d相对生长量 (%) Relative biomass after 14 d	地上部分 Shoot	地下部分 Root
0	55.2±7.4^a	73.8±1.2^a	90.9±0.4^a
10	49.3±8.0^a	69.2±2.4^b	89.7±0.7^ab
50	37.2±10.0^b	69.5±2.9^b	88.9±1.7^bc
200	19.2±4.1^c	66.2±0.9^bc	87.6±1.5^cd
500	11.7±6.9^c	62.6±4.0^c	87.5±0.4^d

镉处理 Cd²⁺ treatment (μmol·L^-1)	14 d相对生长量 (%) Relative biomass after 14 d	含水率 Water content(%)
镉处理 Cd²⁺ treatment (μmol·L^-1)	14 d相对生长量 (%) Relative biomass after 14 d	地上部分 Shoot	地下部分 Root
0	55.2±7.4^a	73.8±1.2^a	90.9±0.4^a
10	49.3±8.0^a	69.2±2.4^b	89.7±0.7^ab
50	37.2±10.0^b	69.5±2.9^b	88.9±1.7^bc
200	19.2±4.1^c	66.2±0.9^bc	87.6±1.5^cd
500	11.7±6.9^c	62.6±4.0^c	87.5±0.4^d

镉处理 Cd²⁺ treatment (μmol·L^-1)	植株各部分中Cd²⁺浓度 Cd²⁺ content in different parts of plant (mg·kg^-1 DW)			植株各部分吸收镉占柽柳吸收镉的比例 Cd²⁺ content in different parts/overalls absorb content (%)			富集系数^* Accumulation coefficient
镉处理 Cd²⁺ treatment (μmol·L^-1)	营养枝 Nutritional branch	枝条 Branch	根系 Roots	营养枝 Nutritional branch	枝条 Branch	根系 Roots	富集系数^* Accumulation coefficient
0	0^a	0^a	0^a	-	-	-	-
10	50.85±7.51^b	25.97±2.34^b	1 579.38±92.04^b	12	2	86	0.59
50	68.54±4.34^b	60.38±9.34^c	2 694.67±603.70^c	8	2	90	0.19
200	89.44±12.30^c	82.11±6.77^d	5 415.86±336.16^d	5	2	93	0.11
500	56.00±2.61^b	89.09±7.95^d	10 679.03±1 009.94^e	1	2	97	0.06