不同根际温度对黄瓜幼苗生长、光合及叶绿素荧光特性的影响

摘要

The effects of 20 ℃,25 ℃,30 ℃,35 ℃ root-zone temperature gradient on the growth,photo-synthesis and chlorophyll fluorescence characteristics of cucumber seedlings were investigated by nutrient solution culture method.The results showed that the seedlings had the largest amount of growth in 25 ℃ root-zone temper-ature,the relative chlorophyll content(SPAD),root activity,net photosynthetic rate(Pn ),excitation energy cap-ture efficiency of photosystem Ⅱ(PSⅡ)reaction center(Fv′?Fm′),actual photochemical efficiency of PSⅡ(ΦPSⅡ)and photochemical fluorescence quenching coefficient(qP)were the maximum in 4 treatments and the excited energy pressure of PSⅡ(1 -qP),partition imbalance of excited energy between PSⅠ and Ⅱ(β?α-1)were the minimum after treated 5 days,while the parameters showed a contrary tendency under 35 ℃ treatment.The pro-portion of absorbed light energy used for photochemical reaction(P)at 25 ℃ was the biggest,while the proportion of absorbed light energy used for antenna heat dissipation(D)at 35 ℃ was the highest,reaching up to 70.2%. The results suggested that the most suitable root-zone temperature for cucumber seedling was 25 ℃,higher or lower temperature would affect its growth,and the influence of high temperature was more serious.%采用营养液栽培法，研究了20℃、25℃、30℃、35℃4个根际温度处理5 d 后黄瓜幼苗生长、光合和叶绿素荧光参数的变化。结果显示：黄瓜幼苗在25℃的根际温度中生长量最大，相对叶绿素含量（SPAD）、根系活力、叶片净光合速率（Pn ）、光系统Ⅱ（PSⅡ）反应中心的光能捕获效率（Fv′？Fm′）、PSⅡ的实际光化学效率（ΦPSⅡ）以及光化学猝灭系数（qP）在4个处理中均为最大，PSⅡ激发能压力（1－qP）及 PSⅠ、PSⅡ间激发能分配的不平衡性（β？α－1）均为最小；35℃处理下各参数则表现为相反趋势；25℃处理下，PSⅡ吸收的光能用于光化学反应的比例（P）最大，而35℃下吸收的光能用于天线热耗散的比例（D）最大，达70．2％。试验表明，黄瓜幼苗最适宜于25℃的根际环境，温度过高或过低都会影响其生长，且高温影响尤为严重。