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为探究外源5-氨基乙酰丙酸(ALA)对低温胁迫下玉米幼苗生长及光合特性的调控效应,以绥玉13(低温敏感型)和郑单958(耐低温型)为试验材料,于三叶一心期叶面喷施20mg/L ALA,在昼/夜温度为14℃/5℃的低温条件下培养48h,恢复常温48h后取样,分析外源ALA对玉米幼苗生长、叶绿素含量、光合作用参数及叶绿素荧光特性的影响。结果表明:低温胁迫显著抑制两个玉米品种幼苗的株高、叶面积、鲜重和干重。低温处理导致幼苗SPAD值下降,叶片净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO_2浓度(C_i)、最大荧光(F_m)、最大光化学效率(F_v/F_m)、潜在光化学效率(F_v/F_o)及光化学猝灭系数(q_P)水平降低,初始荧光(F_o)和非光化学猝灭系数(NPQ)升高。外源ALA能够促进低温胁迫下玉米幼苗形态建成与物质积累,叶片SPAD值增加。外源ALA能够缓解由低温胁迫导致的叶片P_n、T_r、G_s和C_i下降,提高F_m、F_v/F_m、F_v/F_o及q_P水平,降低F_o和NPQ水平。由此可见,外源ALA能够促进叶片光合作用,提高PSⅡ反应活性,促进物质积累,增强玉米苗期的抗低温能力,且对低温敏感型玉米品种的缓解低温伤害效果更好。
In order to explore the regulatory effect of exogenous 5-aminolevulinic acid (ALA) on the growth and photosynthetic characteristics of maize seedlings under low temperature stress, Suiyu 13 (low temperature sensitive) and Zhengdan 958 (low temperature resistant) The leaves were sprayed with 20 mg / L ALA at the leaf clover leaf phase for 48 hours under the condition of day / night temperature of 14 ℃ / 5 ℃. After 48 hours of recovery, the samples were taken for analysis of the effects of exogenous ALA on the growth, chlorophyll content, photosynthesis Effect parameters and chlorophyll fluorescence characteristics. The results showed that cold stress significantly inhibited plant height, leaf area, fresh weight and dry weight of two maize varieties. Low temperature treatment resulted in the decrease of SPAD value, P n, T_r, G_s, C_i, F_m, F_v / F_m ), The potential photochemical efficiency (F_v / F_o) and the photochemical quenching coefficient (q_P) decreased, while the initial fluorescence (F_o) and non-photochemical quenching coefficient (NPQ) increased. Exogenous ALA can promote the seedling formation and material accumulation of maize seedlings under low temperature stress, and the leaf SPAD value increased. Exogenous ALA could alleviate the decline of P_n, T_r, G_s and C_i induced by low temperature stress and increase the levels of F_m, F_v / F_m, F_v / F_o and q_P, and decrease the F_o and NPQ levels. Thus, the exogenous ALA can promote leaf photosynthesis, improve PS Ⅱ reactivity, promote material accumulation and enhance the anti-low temperature ability of maize seedlings, and it is more effective to alleviate the cold damage of low temperature sensitive maize varieties.