烤烟幼苗根系在低温胁迫后的形态及生理生态响应

根系作为重要的吸收器官和代谢器官,其生长状况不仅直接控制着植物吸收水分和养分,而且制约着植株地上部分生长的好坏。温度是影响烤烟幼苗根系发育的重要因素之一。南方多数烟区育苗阶段早春低温严重,影响着健壮烟苗的培育。为此,选用云烟87(YY87)、Msk326(K326)和云烟85(YY85)等3个品种烤烟幼苗,在5～7℃条件下分别处理2,4及6d,研究烤烟幼苗根系在低温胁迫后的形态及生理生态响应。结果表明:YY87低温胁迫处理不同时间后,SOD,POD,CAT酶活性均有不同程度上升;K326在处理2 d及4 d后,3种酶活力均较对照明显下降;而YY85的SOD酶活性上升,CAT和POD活性则表现下降。就根系活力而言,YY87在不同低温处理时间均表现为上升;而K326及YY85则表现为短时间(2d)低温胁迫根系活力受到抑制,随着处理时间延长,其根系活力又逐渐增强。低温处理2d后,YY87根平均直径、根表面积和根体积显著下降,但随着胁迫时间延长则恢复正常;K326则在低温处理2d后根直径、根长、根表面积和根体积均达到最大,其后逐渐降低;YY85则表现根表面积和体积均有不同程度下降。由此表明,不同品种幼苗根系受到低温胁迫后其根系形态及生理生态指标存在着不同的响应机制。

Physiological Ecological Respinse of Roots of Flue-Cured Tobacco Seedlings in Low Temperature Stress

Roots is major organic of plants which is not only responsible for absorbing water but also affect above-ground growth of plants.Temperature is one of important factors which affect growth and development of root of Flue-cured tobacco Seedling.Low temperature at early spring limit culture of strong seedling in southern tobacco cultivated area.In order to study morphological and Physiological ecological response of root of Flue-cured tobacco seedling after low temperature stress,the experiment was conducted with different stressful period which is 2d,4d and 6d under the 5℃(night)-7℃(day) by the material named respectively Yunyan87,Msk326 and Yunyan85.The results showed that comparing with favorable temperature 23℃(night)-25℃(day),activities of SOD,POD,CAT and root vigor have different change trends with difference variety,which all of four parameter increase for YY87 and other parameter decrease after low temperature stress for short-term(2d) as for as K326 and YY85 but activities of SOD rise for YY85,prolong low-temperature stress period,some these parameters come to raise gradually.As for morphological parameter,average diagram,surface area,volume of root declined significant after low-temperature stress for 2d for YY87 while these morphological parameter are similar to normal level if prolonging stress to 6d.however all morphological parameter are opposite for K326 comparing with YY87.Surface area,volume of root declined to some extent for YY85.These conclusions indicated that is different of morphological and Physiological ecological response mechanisms for root of flue-cured tobacco seedling of different variety after low temperature stress.