生长调节剂对低温胁迫下酸橙幼苗抗逆生理指标的影响

摘要

[Objective] In order to reveal feasibility of different concentrations of BRs,BT and SA on Citrus aurantium under low temperature stress,the effects of BRs,BT and SA on physiological index were studied.[Method] Pot C.aurantium seedlings cultured under the same outdoor conditions were sprayed on the leaves with BRs,BT and SA separately,and then placed in the low incubator [0 ℃/4 ℃ (day/night),light intensity of 600 μmol · m-2s-1],and the seedlings sprayed with distilled water and set at 25 ℃ were served as control Ⅰ (CK1),and the seedlings sprayed with distilled water and set at low temperature stress (0 ℃/4 ℃,day/night) were served as control Ⅱ (CK2).The relative electric conductivity,contents of proline,malondialdehyde,soluble protein,chlorophyll,and activities of SOD,POD and CAT were measured.[Result] Compared with normal temperature CK1,low temperature significantly inhibit the antioxidant enzyme activity of CK2,enhanced the cell membrane damage and brought about loss of the normal functions of cell membrane.Thus,low temperature stress caused some increase in relative electric conductivity and MDA content of C.aurantium seedlings.Low temperature stress treatment also destroyed the structure of the chloroplast,causing the decomposition of photosynthetic pigment and reducing the content of chlorophyll and carotenoid.Compared with CK2,0.15 mg.L-1 BRs,10 mmol · L-1 BT,1 mmol.L-1 SA enhanced the activities of POD,SOD,and CAT,increased the contents of proline and soluble protein,and effectively reduced the damage of low temperature stress on cell membrane.At the same time,the exogenous BRs,BT and SA increased the contents of chlorophyll and carotenoid,the efficiency of leaf photosynthesis and thus effectively resisted the oxidative stress caused by low temperatures.But with the increasing concentration of spraying,the ability of C.aurantium to resist low temperature stress decreased.[Conclusion] The foliage spraying with BRs,BT and SA could reduce the damage of low temperature stress on C.aurantium seedling leaves.%[目的]分析不同浓度BRs、BT和SA对低温胁迫下酸橙幼苗抗逆生理指标的影响,寻找缓解酸橙幼苗低温伤害的可行方法,为酸橙的推广种植提供技术参考.[方法]以盆栽酸橙幼苗为材料,叶面分别喷施不同浓度油菜素内酯(BRs)、甜菜碱(BT)和水杨酸(SA)溶液后,置于4℃/0℃(昼/夜)、光照600 μmol·m-2s-1的人工气候箱内,进行低温胁迫处理.以常温(温度25℃/23℃(昼/夜),光照600 iμmol·ml s-1)下喷施蒸馏水为CK1,以低温胁迫(4℃/0 ℃(昼/夜),光照600 μmol·m“s-1)下喷施蒸馏水为CK2.低温胁迫处理3天后,测定酸橙幼苗叶片细胞膜透性、丙二醛、脯氨酸、可溶性蛋白、叶绿素含量,以及SOD、POD、CAT抗氧化酶活性.[结果]与CK1相比,低温显著抑制CK2酸橙幼苗叶片抗氧化酶活性,加重低温对细胞膜的伤害,致使细胞膜结构被破坏,不能正常行使其功能,进而引起酸橙幼苗叶片相对电导率和丙二醛含量显著上升.低温处理也会导致叶绿体结构被破坏,引起光合色素的分解,致使叶绿素和类胡萝卜素含量显著下降,不能正常进行光合作用.与CK2相比,叶面喷施生长调节剂可以显著提高酸橙幼苗叶片脯氨酸和可溶性蛋白含量,减轻酸橙幼苗叶片因低温而导致的细胞失水;提高SOD、POD、CAT抗氧化酶活性,有效清除细胞内过多的活性氧,避免膜脂过氧化的发生,显著降低叶片丙二醛含量和相对电导率,使细胞膜系统代谢正常,减轻低温胁迫对酸橙幼苗叶片造成的伤害.同时,叶面喷施生长调节剂显著提高叶片叶绿素与类胡萝卜素含量,减弱低温对光合作用的抑制影响.随着浓度的升高,生长调节剂对酸橙幼苗低温伤害的缓解作用呈现先增强后减弱的趋势,其中以叶面喷施0.15 mg·L-1BRs、10 mmol· L-1BT、1 mmol.L-SA溶液的效果最为明显.[结论]叶面喷施浓度为0.15 mg·L-1BRs、10 mmol·L-1BT、1 mmol·L-1SA溶液可明显减轻低温胁迫对酸橙幼苗叶片的伤害.