外源5-氨基乙酰丙酸对低温胁迫下玉米幼苗生长及光合特性的影响

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CO₂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。

Effects of Exogenous ALA on Growth and Photosynthetic Characteristics of Maize Seedlings under Low Temperature Stress

The objective of this study was to investigate the seedling growth and photosynthetic characteristics of exogenous ALA-enhanced maize seedlings under low temperature stress. This experiment was conducted with maize cultivars Suiyu 13 (cold sensitivity) and Zhengdan 958 (cold resistance), which grew up to three-leaf, then were treated with low temperature of 14℃/5℃(day/night) for 48h, and then got recovery for 48h. Plant morphological growth, chlorophyll content, photosynthetic parameters, chlorophyll fluorescence characteristics were measured. The results showed that seedling height, leaf area, fresh weight and dry weight decreased significantly under low temperature stress. All the decreases in SPAD value, P_n, T_r, G_s, C_i, F_m, F_v/F_m, F_v/F_o, q_P and the increases in F_o and NPQ reflected the inhibitory effects of low temperature stress. Exogenous ALA could promote the matter accumulation and morphogenesis, increase SPAD value of maize seedlings under low temperature stress. Exogenous ALA application led to a marked increase in P_n, T_r, G_s, C_i, F_m, F_v/F_m, F_v/F_o and q_P, and reduce F_o and NPQ of two maize varieties. Therefore, spraying exogenous ALA could promote the photosynthesis , PSⅡ reactivity and matter accumulation, as well as enhanceed the low temperature resistance of maize seedlings. The alleviation effect of exogenous ALA was better in cold sensitivity type under low temperature stress.