干旱胁迫对甜菜块根膨大期光合光响应特性的影响

Effects of Drought Stress on Photosynthetic Characteristics of Photosynthesis during Sugarcane Root Expansion

【目的】研究干旱胁迫对甜菜块根膨大期叶片光合光响应特性的影响。【方法】以H1352(耐旱型)、81GM26(旱敏感型)甜菜品种为材料,设置2个灌水处理,通过对叶片净光合速率与光强响应曲线的模拟得出最大净光合速率(Pn max)、暗呼吸速率(Rd)、表观量子效率(AQY)、光补偿点(LCP)和光饱和点(LSP)主要光合参数。【结果】H1352、81GM26甜菜品种叶片Pn均随着PAR的增大先呈线性增加,后急速增大,最终渐趋平稳或下降;在不同PAR条件下,2品种叶片净光合速率表现为对照大于干旱胁迫处理,且随PAR的增大,各处理间差异达极显著水平。干旱胁迫降低叶片最大净光合速率和光饱和点(P<0.01),各处理间差异达极显著水平。H1352和81GM26品种在干旱胁迫条件下最大净光合速率分别为24.8和21.0μmol/(m 2·s),分别比对照低18%和26%;光补偿点分别为600和601μmol/(m 2·s),分别比对照低18.5%和16.4%,叶片光适应范围变窄,光能利用能力降低。H1352品种在干旱胁迫条件下叶片暗呼吸速率降低,比对照降低40.3%,处理间差异达极显著水平;而81GM26品种处理间没有显著差异。【结论】甜菜块根膨大期遭遇40%~45%田间持水量的干旱胁迫时,其叶片最大净光合速率、暗呼吸速率、光饱和点降低,光补偿点和表观量子效率因品种而异,光能利用区间变窄,光能利用能力减弱;干旱条件下耐旱型品种H1352光合能力下降幅度低于旱敏感型81GM26。

【Objective】To explore the effects of drought stress on photosynthetic characteristics of sugar beet root during expansion period.【Methods】Two irrigation treatments were set up with H1352(drought-tolerant type)and 81GM26(drought-sensitive type)sugar beet varieties,and the maximum net photosynthetic rate(Pn max),dark breath rate(Rd),apparent quantum efficiency(AQY),light compensation point(LCP)and light saturation point(LSP)main photosynthetic parameters were obtained by simulating the response curves of leaf net photosynthetic rate and light intensity.【Results】The results showed that the leaf Pn of H1352 and 81GM26 sugar beet varieties increased linearly with the increase of PAR,then increased rapidly,and finally became stable or decreased.Under different PAR conditions,the net photosynthetic rate of the leaves of the two varieties was higher than that of drought stress treatment,and with the increase of PAR,the difference between the two treatments reached a very significant level.Drought stress reduced the maximum net photosynthetic rate and light saturation point of the leaves(P<0.01).The difference among the treatments was very significant.The maximum net photosynthetic rates of H1352 and 81GM26 under drought stress were 24.8 and 21.0μmol/(m 2·s),respectively,which were 18%and 26%lower than those of the control,respectively;The light compensation points were 600 and 601μmol/(m 2·s),respectively,which were 18.5%and 16.4%lower than that of the control,respectively.The light adaptation range of the leaves was narrowed and the light energy utilization ability was reduced.Under the drought stress condition,the dark respiration rate of H1352 variety decreased significantly,which was 40.3%lower than that of the control,while there was no significant difference between the treatments of 81GM26 variety.【Conclusion】When sugar beet root tuber was exposed to drought stress with water holding capacity 40%-45%field,the maximum net photosynthetic rate,dark respiration rate and light saturation point of sugar beet decreased,the light compensation point and apparent quantum efficiency varied with varieties,the range of light energy utilization narrowed and the ability of light energy utilization weakened.Under drought condition,the photosynthetic capacity of drought-tolerant variety H1352 was lower than that of drought-sensitive 81GM26.