低温胁迫对不同抗寒性甘蔗品种幼苗叶绿体生理代谢的影响

土培桶栽抗寒品种GT28与不抗寒品种ROC22，测定正常(28℃)和低温(4℃)条件下甘蔗幼苗叶片的质膜透性、叶绿素荧光参数等相关生理指标。结果表明，低温与正常条件下相比，两品种幼苗叶片的膜透性显著增大，且ROC22增幅较大；初始荧光(F_o)、非光化学猝灭系数(NPQ)显著上升，最大光能转化效率(F_v/F_m)、反应中心激发能捕获效率(F_v'/F_m')、光化学猝灭系数(q_P)、PSII实际量子效率(Φ_PSII)均下降，以ROC22降幅较大；叶绿体希尔反应活力、Mg²⁺-ATPase、Ca²⁺-ATPase活性下降，叶绿体中丙二醛(MDA)含量增加，以ROC22变幅较大；超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)活性均上升，GT28的增幅比ROC22显著。上述参数与品种抗寒性密切相关，GT28比ROC22抗寒性更强。

Effect of Chilling Stress on Physiological Metabolism in Chloroplasts of Seed-lings of Sugarcane Varieties with Different Chilling Resistance

Chilling occurs frequently in recent years, and has become a major limiting factor for sugarcane production. Chloroplasts are the main organelle for photosynthesis and one of the subcellular fractions for chilling sensitivity in plants. In order to investigate the effect of chilling stress on the physiological metabolism of sugarcane chloroplast, and reveal the relationships between the physiological characteristics in chloroplast and chilling tolerance of sugarcane, the experiment was conducted with two varieties of GT28 (chilling resistant) and ROC22 (chilling susceptible) with two treatments: control (28°C) and chilling stress (4°C). The relative electrical conductance (REC) of sugarcane seedling leaves, and chlorophyll fluorescence parameters and some physiological indiees in chloroplasts were measured. The results showed that under the low temperature stress condition, the plasma membrane permeability of the seedling leaves, initial fluorescence (F_o) and NPQ increased significantly in both varieties, and the chilling resistant variety GT28 was more stable than the chilling sensitive variety ROC22; and theF_v/F_m, F_v''/F_m'', q_P, and Φ_PSII decreased in the two sugarcane varieties, and decreased less in GT28 than in ROC22. The activities of Hill reaction, Mg²⁺-ATPase and Ca²⁺-ATPase in chloroplasts decreased, and those in GT28 decreased less than those in ROC22. The MDA content and SOD, POD, GR activities in the chloroplasts increased, and sugarcane variety GT28 showed lower increase in MDA but higher increase in SOD, POD, GR activities. The chlorophyll fluorescence parameters and the physiological characteristics in the chloroplasts of sugarcane leaves were affected significantly by chilling stress. The changes of chlorophyll fluorescence and the physiological characteristics in the chloroplasts are correlated significantly to low temperature resistance, and GT28 is more chilling resistant than ROC22.