红树植物秋茄幼苗对镉耐性的研究

STUDY ON THE TOLERANCE OF KANDELIA CANDEL MANGROVE SEEDLINGS TO CADMIUM

土培和砂培相结合，以不同镉浓度处理秋茄幼苗的试验结果表明：１００ｍｇ／Ｌ镉浓度对种苗萌发产生显著抑制效应：第２对叶萌发百分率在１３．３％以下。在幼苗生长阶段，砂培２５ｍｇ／Ｌ组，幼苗（植物体平均镉含量１４６．４３μｇ／ｇ）受严重伤害致死；土培２５ｍｇ／ｋｇ，幼苗（镉含量２７．２４μｇ／ｇ）生长正常；达５０ｍｇ／ｋｇ时，幼苗（镉含量３０．４７μｇ／ｇ）生长明显受抑制，生物量和高度生长量分别比对照降低１９．５４％和２５．０２％，因此植物体镉积累浓度是抑制幼苗生长的主要因素之一，与其他陆生木本植物相比，秋茄属高耐性植物。根据秋茄幼苗根与其它器官镉含量的比值变化，确定土培幼苗体内耐受镉的临界值大约为３０μｇ／ｇ。

eedlings of Kandelia candel mangrove were treated with different concentrations of Cdin soil culture and sand culture under the same conditions。The results show that the treat-ment with Cd at a level of 100 mg/kg has a significantly inhibitive effect on the germinationof the seedlings,with the second pair of cotyledons germinated at a rate of below 13.3%。Inthe stage of seedling growth,the seedlings growing in a sand culture treated with 25 mg/L ofCd were heavily injured,with an average content of 146.43μg Cd/g tissue , and died aftergrowing for 65 days。The seedlings growing in a soil culture treated with 25 mg/kg of Cdwere normal to grow,with an average content of 27.24μg Cd/g tissue,and those treated withup to 50 mg/kg of Cd had a significantly innibited growth,with an average content of30.47μg Cd /g tissue,and the biomass and height reduced by 19. 54%and 25. 02%,respec-tively,relative to control.This indicates that the level of cadmium accumulated in the plant isone of the main factors inhibiting the growth of the seedlings。As compared with other terres-trial xylophyta,K. candel is a plant resistant to a higher Cd pollution。Based on the ratio ofCd level in the roots to that in other organs of the seedlings,the critical value of Cd in tissuethat the seedlings growing in a soil culture can tolerate was determined to be about 30μgCd/g tissue。