不同抗旱性春小麦叶绿素荧光特性对施氮量和灌溉水平的响应

Effects of nitrogen application rates and irrigation levels on leaf chlorophyll fluorescence parameters of spring wheat cultivars with a different drought resistance

在大田条件下,以3个抗旱性不同的春小麦品种为材料,通过控制灌水量和施氮量,研究旗叶叶绿素荧光特性对氮素和水分的响应.结果表明:小麦旗叶叶绿素质量分数、最大光化学效率、实际光化学效率及光化学淬灭系数均随施氮量的增加先升高后下降,非光化学淬灭系数、热耗散速率先降低后升高,但升高幅度较小.抗旱品种和尚头与西旱2号、不抗旱品种宁春4号在施氮量分别为150、225 kg/hm^2时,叶绿素质量分数、最大光化学效率、实际光化学效率、光化学淬灭系数最高,非光化学淬灭系数和热耗散速率最低.施氮量相同条件下,抗旱品种和尚头与西旱2号叶绿素荧光参数对灌水量响应的差异不显著,宁春4号充分灌水条件下的最大光化学效率、实际光化学效率、光化学淬灭系数均显著高于有限灌水,非光化学淬灭系数、热耗散速率则显著低于有限灌水.3品种小麦叶绿素质量分数与光化学效率和光化学淬灭系数呈正相关关系,与非光化学淬灭系数和热耗散速率呈负相关关系.增施氮肥有助于提高小麦叶片PSⅡ反应中心的开放比例和光化学效率,但施氮量过高(和尚头与西旱2号超过150 kg/hm^2,宁春4号超过225 kg/hm^2)导致小麦叶片将更大比例光能向热耗散分配,热耗散速率升高.抗旱品种叶绿素荧光参数受水分的影响小于不抗旱品种.

To study the responses of flag leaf photosynthesis to nitrogen and moisture levels,three spring wheat cultivars with different drought resistance were used in a field experiment of five nitrogen rates and two irrigation levels.The results showed that the chlorophyll content of wheat flag leaves,the maximum photochemical efficiency,the actual photo-chemical efficiency and photo-chemical quenching first increased and then decreased with increasing nitrogen rates,while non photo-chemical quenching and heat dissipation rates declined and then increased,but to a lesser extent.The chlorophyll content,the maximum photo-chemical efficiency,the actual photo-chemical efficiency and the photo-chemical quenching were the highest and non photochemical quenching and heat dissipation were the lowest when nitrogen rates for the drought resistant cultivars Heshangtou and Xihan No.2 were 150 kg/hm2,and for the non-drought resistant cultivar Ningchun No.4 it was 225 kg/hm2.At the same nitrogen rate,differences in chlorophyll fluorescence parameters of Heshangtou and Xihan No.2 were not significant under two irrigation conditions,but the maximum photo- chemical efficiency,actual photo- chemical efficiency and photo- chemical quenching of Ningchun No.4 under sufficient irrigation condition were significantly higher than those under the limited irrigation and non photo-chemical quenching and the heat dissipation rate was significantly lower under full irrigation than under the limited irrigation.The photo-chemical efficiency and photo-chemical quenching of the three wheat cultivars were positively correlated with chlorophyll contents,and non photo-chemical quenching and heat dissipation rates were negatively correlated with chlorophyll contents.Increased nitrogen rate helped increase the proportion of openness and efficiency of PS Ⅱ photochemical reaction center in wheat leaves,but excessive amounts of nitrogen（over 150 kg/hm2 for Heshangtou and Xihan No.2and 225 kg/hm2 for Ningchun No.4） resulted in a greater distribution of light energy to heat dissipation and,therefore,a higher heat dissipation rate.The chlorophyll fluorescence parameters of the drought resistant cultivars were less affected by soil moisture than non-drought cultivars.