Ca^(2+)对根际低氧胁迫下黄瓜幼苗生长和叶片荧光特性的影响

Effect of Calcium on Growth and Chlorophyll Fluorescence of Cucumber Seedlings under Hypoxia

采用营养液栽培,以根际低氧耐性不同的2个黄瓜品种为试验材料,研究了Ca2+对根际低氧胁迫下黄瓜幼苗生长和叶片荧光特性的影响。结果表明:(1)根际低氧胁迫下,黄瓜植株根长、根表面积和根尖数减少,但根径有所增大;叶片干重、鲜重和叶面积显著减小,提高营养液钙浓度可使植株叶片干、鲜重和叶面积得到部分恢复。(2)根际低氧胁迫下,叶片光合色素含量降低,提高营养液钙浓度对色素含量无明显影响。(3)根际低氧胁迫下,常钙和高钙处理黄瓜叶片Fv/Fm与通气常钙(CK)无显著差异,但低氧缺钙处理的Fv/Fm显著降低;与通气常钙相比,根际低氧胁迫处理的光化学猝灭(qP)减小、非光化学猝灭(qN)增大、光合功能相对限制值(L(PFD))升高,提高营养液钙浓度可使qP和qN恢复至近对照水平,而使L(PFD)低于对照,且‘绿霸春四号’黄瓜品种表现得更为突出;根际低氧胁迫下,光化学速率(Prate)减小,天线热耗散速率(Drate)都随钙浓度升高而降低。总之,根际低氧胁迫下黄瓜幼苗生长被显著抑制,PSⅡ反应中心受到一定程度的破坏,提高钙浓度可使PSII反应中心恢复至接近甚至高于通气对照的水平,从而有效缓解根际低氧胁迫对黄瓜幼苗造成的伤害。

With two cucumber cultivars of ＇Zhongnong 8＇ and ＇ Lubachun No. 4＇,the effect of calcium on growth and chlorophyll fluorescence of cucumber seedlings under hypoxia was studed. It showed that root growth was inhibited under hypoxia,demonstrated by decreased root length（L）, total surface area（SA） and number of tip s（Ntips） and increased root average diameter（AD）. Fresh and dry weight of leaf and leaf area dropped significantly while those with high concentration calcium application under hypoxia showed approaching tendency to the seedlings in control. Pigment concentration witnessed a drop in seedlings under hypoxia and was almost stable in those with high concentration calcium application under hypoxia. Fv/Fm remained constant between seedlings in control and those with hypoxia stress. However,an obvious decrease was observed in calcium-deficient seedling under hypoxia. A fall in qP and P and a rise in qN and L（PFD） can be found in seedlings with hypoxia and qP,qN showed near-to-control in those with high concentration calcium under hypoxia. Drate vary in different cultivars when seed lings were applied with high concentration calcium. The growth was inhibited and reaction center of PSⅡ was damaged when cucumber seedlings exposed to hypoxia and high concentration calcium can alleviate injury caused by hypoxia effectively.