预喷施CaCl_2溶液对低温胁迫下烤烟幼苗生理生态的影响

Influences of CaCl_2 Pre-spray on Ecophysiology of Nicotiana tabacum L.Seedlings Under Chilling Stress

温度是决定烤烟幼苗生长发育的重要因子之一,影响着烟叶最终的产量和品质.南方多数烟区育苗阶段早春低温影响着健壮烟苗的培育.该研究选用云烟87和Msk326 2个烤烟品种烟苗预喷施质量分数为0.5%,1.0%,1.5%及2.0%的CaCl2溶液后进行低温(8℃)处理72 h,然后测定烟苗光合参数、叶绿素相对质量分数、膜保护酶、渗透调节物质可溶性糖和游离脯氨酸等生理指标,研究预喷施CaCl2溶液对低温胁迫下烤烟幼苗的生理生态影响.结果表明:2个品种的低温对照CK2光合指标除云烟87的胞间二氧化碳质量分数较常温对照未达到极限著水平外,其他光合指标、过氧化氢酶(CAT)及过氧化物酶(POD)活性均显著低于常温对照CK1;预喷施1.0%CaCl2溶液可有效提高过氧化氢酶(CAT)及过氧化物酶(POD)活性,增加可溶性糖和游离脯氨酸质量分数,减少丙二醛(MDA)质量分数,提高烟苗耐低温胁迫的能力,从而维持烟苗正常光合作用.

Temperature is one of the important factors which affect the growth, development, yield and quality of flue-cured tobacco. In southern tobacco-cultivating area of China, lower temperature weather fre-querntly occurs in early spring, which limits the culture of healthy and vigorous tobacco seedlings. In an experiment reported in this paper, the young seedlings of tobacco varieties YunYan87 （YY87） and Msk326 were pre-sprayed with CaC12 solutions at 0.5%, 1. 0%, 1.5 % and 2.0% before exposing them to 8℃ and 25℃ for 72 h, and then photosynthetic indexes, antioxidant enzyme activities and contents of soluble sug- ars, free proline and malondialdehyde （MDA） were measured so as to study the ecophysiological adaptation of the seedlings under chilling stress. The results showed that net photosynthesis （Pn）, conductance （Gs）, transpiration rate （Tr）, activities of catalase （CAT） and peroxidase （POD） and soluble sugar contents for YY87 and K326 seedlings under chilling stress were reduced significantly compared with normal temperature （25℃） control seedlings, but intercellular CO2 concentration （Ci） showed no significant difference for YY87 under chilling stress. Pre-spraying CaC12 solutions helped to alleviate the chilling damage to a certain extent, and a CaCl2 concentration of 1.0% effectively increased CAT and POD activities, enhanced the contents of soluble sugars and free proline and decreased malondialdehyde （MDA） content of of the seedlings under chilling stress, thus improving cold resistance of flue-cured tobacco seedlings and maintaining their normal photosynthetic metabolism.