镉胁迫对薄壳山核桃幼苗生长的影响

Effects of Cadmium Stress on Seedling Growth of Carya illinoinensis

为探究镉胁迫对薄壳山核桃幼苗生长发育的影响,本研究以薄壳山核桃实生幼苗为试验材料,采用营养液水培育苗试验方法,测定不同浓度镉[0(CK)、5、10、20、40、80 mg·L-1]处理下薄壳山核桃幼苗各项生理指标。结果表明,镉胁迫对薄壳山核桃的生长发育具有显著的抑制作用,且镉浓度越高抑制作用越明显。随着镉处理浓度的增加,薄壳山核桃幼苗的生物量、根系长度均显著下降,80 mg·L-1镉胁迫下,较CK分别下降了40.11%、56.64%;幼苗根、茎、叶中的镉含量均显著增加,在80 mg·L-1镉胁迫下分别达到5 582、2 235、479 mg·kg-1;根、茎中Mn、Zn、Mg、K元素吸收均受到抑制,但叶中K、Mg元素含量显著上升;叶片中过氧化物酶(POD)和过氧化氢酶(CAT)活性在20 mg·L-1镉胁迫下均达到最高,较CK分别上升726.62%和86.47%;叶片的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)均显著降低,在20 mg·L-1镉胁迫时分别较CK下降了81.44%、81.59%、75.22%,叶片荧光参数原初光能转化效率(ΦPSII)、表观电子传递速率(ETR)和光化学荧光淬灭系数(q P)显著降低,非光化学淬灭系数(q N)值显著升高,光合作用受到严重抑制。综上,镉胁迫可以抑制薄壳山核桃幼苗生物量积累,影响根、茎中各元素的吸收,显著降低叶片光合作用强度,对幼苗生长造成严重危害。本研究为进一步揭示薄壳山核桃的镉耐性与镉富集机理奠定了理论基础。

In order to explore effects of cadmium stress on the growth and development of pecan seedling,pecan seedling was used as testing material,nutrient solution culture method was adopted and the physiological indexes of pecan seedlings were measured under different concentration of cadmium [0（CK）,5,10,20,40,80 mg·L^-1]. The results showed that cadmium stress has a significant inhibitory effect on the growth and development of pecan. The inhibitory effect is more obvious with higher concentration of cadmium. With the increase of the cadmium concentration,biomass and root length decreased significantly,which decreased by 40. 11% and 56. 64% compared with the control group at the concentration of 80 mg·L^-1. The cadmium content in roots,stems and leaves of seedlings rose significantly,and reached 5 582 mg·kg^-1,2 235 mg·kg^-1,479 mg·kg^-1 at the concentration of 80 mg·L^-1. The contents of Mn,Zn,Mg and K in roots and stems were inhibited,but the contents of K and Mg in leaves increased significantly. When the concentration of cadmium was 20 mg·L^-1,the activity of POD and CAT in leaves reached the highest level,and increased by 726. 62%,86. 47% compared with the control group. At the concentration of 20 mg·L^-1,the net photosynthetic rate（Pn）,stomatal conductance（Gs） and transpiration rate（Tr） of leaves dropped dramatically by81. 44%,81. 59% and 75. 22% compared with the control group,respectively. And leaf fluorescence parametersefficiency of primary conversion of light energy（ΦPSII）,apparent electron transfer rate（ETR） and photochemical quenching（q P） decreased significantly while non-photochemical quenching（q N） increased significantly, and photosynthesis was severely inhibited. To sum up,cadmium stress inhibited the biomass accumulation of pecan seedlings and affected the absorption of elements in roots and stems,and significantly reduced the photosynthesis intensity of leaves,causing serious damage to seedling growth. This study laid the foundation for revealing the cadmium tolerance and cadmium enrichment mechanism of pecan.