锌铁单独或复合处理下小麦幼苗光合特性的比较

Comparison of photosynthetic characteristics in wheat seedlings treated with zinc and iron alone and in combination

以西旱3号小麦为材料,比较不同c(Zn)(50、250μmol/L)、300μmol/L Fe单独或Zn-Fe复合(300μmol/L Fe+50μmol/L Zn、300μmol/L Fe+250μmol/L Zn)处理下,小麦幼苗光合特性的变化.结果表明,不同c(Zn)单独处理下,幼苗根茎的生长表现出低浓度促进高浓度抑制的现象, Fe单独处理抑制根茎长的生长, 50μmol/L Zn的加入显著缓解了300μmol/L Fe对根茎生长的抑制作用,而250μmol/L Zn的缓解作用不明显;低c(Zn)处理导致叶片w(叶绿素b)、w(叶黄素)、电子传递效率(ETR)、净光合速率(P_n)和蒸腾速率(T_(r))升高, w(叶绿素a)/w(叶绿素b)减小,高c(Zn)或300μmol/L Fe单独处理使w(光合色素)、实际光化学效率(Y(Ⅱ))、ETR、光化学猝灭(qP)、胞间CO_(2)浓度(C_(i))降低,非光化学猝灭(NPQ)和调节性能量耗散的电子产量(Y(NPQ))增高,单独Fe处理还使最大光化学效率(F_(v)/F_(m))、P_(n)、T_(r)和气孔导度(Gs)均减小;50μmol/L Zn的加入诱导Fe处理幼苗叶片w(类胡萝卜素)、w(叶黄素)、Y(Ⅱ)、ETR、Tr和Gs增大, w(叶绿素a)/w(叶绿素b)减小, 250μmol/L Zn的添加使w(叶黄素)和T_(r)增加.低c(Zn)可促进小麦幼苗的生长,增强小麦幼苗光合色素的合成,有效增加PSⅡ反应中心的开放程度,提高电子传递速率和光能转化效率;高c(Zn)或Fe胁迫抑制小麦幼苗的生长,对小麦叶片的光合系统造成一定程度的损伤,抑制光合作用的进行;适量c(Zn)可缓解Fe对小麦幼苗生长及光合作用的抑制,有效降低Fe毒对植物的伤害.

Wheat cultivar Xihan 3 seedlings were used to analyze and compare photosynthetic characteristics in response to different treatments of c(Zn)(50 and 250μmol/L)and 300μmol/L Fe alone and Zn-Fe combined treatments(300μmol/L Fe+50μmol/L Zn and 300μmol/L Fe+250μmol/L Zn).The results showed that seedlings growth exhibited increase due to low c(Zn)and inhibition to high c(Zn).Fe stress alone showed inhibitory effect on the length of roots and shoots.And also,adding 50μmol/L Zn effectively alleviated the inhibitory effect of Fe treatment of seedlings growth,but the effect of 250μmol/L Zn was not obvious.Low c(Zn)treatment induced increases in w(chlorophyll b)and w(lutein)as well as the values of electron transport rate(ETR),net photosynthesis rate(P_(n))and transpiration rate(T_(r)),while the value of w(chlorophyll a)/w(chlorophyll b)decreased.w(photosynthetic pigment),effective photochemical quantum yield(Y(Ⅱ)),ETR,coefficient of photochemical quenching(qP),and intercellular carbon dioxide concentration(C_(i))were reduced but non-photochemical quenching(NPQ)and quantum yield of regulatory energy dissipation(Y(NPQ))increased in response to high c(Zn)or 300μmol/L Fe treatment alone.The values of maximum photochemical efficiency(F_(v)/F_(m)),P_(n),T_(r) and stomatal conductance(GS)were decreased by Fe treatment alone.Adding 50μmol/L Zn resulted in the increases of w(carotenoid)and w(lutein)as well as the values of Y(Ⅱ),ETR,T_(r) and G_(S) in Fe-stressed seedlings,and decreased the w(chlorophyll a)/w(chlorophyll b)value.The application of 250μmol/L Zn led to increment of w(lutein)and T_(r) value.Taken together,low c(Zn)could promote the growth of wheat seedlings,stimulate the synthesis of photosynthetic pigments,effectively increase the openness of PSⅡreaction centers and accelerate the electron transfer rate and light energy conversion efficiency in wheat seedlings.However,high c(Zn)or Fe stress not only inhibited the growth of wheat seedlings,but also caused a certain degree of damage to the photosynthetic system of wheat leaves and inhibited the progress of photosynthesis.The suitable c(Zn)could alleviate Fe-induced inhibition on wheat seedling growth and photosynthesis,thereby effectively reducing Fe damage to plants.