【目的】探究外源生长调节剂6-BA对太子参生长后期生长及生理的影响,为太子参高效栽培提供理论依据。【方法】采用不同质量浓度(0、20、40、60 mg/L)的6-BA于5月中旬进行叶面喷施处理,测定其对太子参块根生长、抗氧化酶系统及光合特性的影响。【结果】①与对照相比,各6-BA处理组太子参块根长、块根直径、鲜根产量、单株生物量、地上部分干质量、地下部分干质量均显著增加;以60 mg/L处理效果最佳,其中,鲜根产量和单株生物量分别比CK提高35.41%和41.60%,均与CK差异显著(P<0.05)。②适当质量浓度的6-BA处理显著提高了试验期间太子参叶片SOD、POD活性以及叶绿素和类胡萝卜素含量,有效缓解MDA含量上升和光合色素下降的趋势。③各6-BA处理组均不同程度提高了太子参的净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r),降低了胞间二氧化碳浓度(C_i),有效缓解了主要由非气孔限制导致的光合“午休”现象;以60 mg/L处理效果最佳,P_n日均值、峰值和谷值分别比对照增加51.76%、41.24%和64.47%。④与对照相比,各6-BA处理组均不同程度提高了试验期间太子参叶绿素荧光参数F_v/F_m、F_v'/F_m'、Φ_PSⅡ和qP,降低了NPQ值。⑤适宜质量浓度(60 mg/L)的6-BA处理显著提升了φ_Po、ψ_o、φ_Eo、E_ABS/CSm、E_TRo/CSm、E_ETo/CSm和c_PIabs,降低了φ_Do和E_DIo/CSm,说明6-BA处理增强了PSⅡ光能吸收与分配利用效率及叶片比活性,缓解了过剩激发能导致的光抑制。【结论】适宜质量浓度的6-BA处理可以有效增强太子参生长后期叶片抗氧化活性和光合性能,促进生长,提高块根产量。光合性能的改善与叶片抗氧化活性及PSⅡ光化学活性的增强有关。

【Objective】This research aims to investigate the effects of exogenous growth regulator 6-BA on the growth and physiology of Pseudostellaria heterophylla at the late growth stage and to provide a theoretical basis for efficient cultivation of P. heterophylla.【Method】 Different concentrations of 6-BA (0, 20, 40, 60 mg/L) were applied to the leaves in mid-May to determine the effects of 6-BA on root tuber growth, the antioxidant enzyme system, and the photosynthetic characteristics of P. heterophylla. 【Result】 (1) Compared to the control (CK), the root length, root diameter, fresh root yield, biomass per plant, dry weight of the aboveground part, and dry weight of the underground part of P. heterophylla in each 6-BA treatment group were significantly increased, with the 60 mg/L treatment showing the most pronounced effect. The fresh root yield and biomass per plant increased by 35.41% and 41.60%, respectively, compared to the CK, and these differences were statistically significant (P < 0.05). (2) The 6-BA treatment with an appropriate mass concentration significantly increased the activities of SOD and POD, as well as the chlorophyll and carotenoid contents in P. heterophylla leaves during the experiment. It also effectively mitigated the rising trend of MDA content and the declining trend of photosynthetic pigments. (3) The P_n, G_s, and T_r of P. heterophylla increased to varying degrees while C_i decreased, effectively alleviating the "nap" phenomenon of photosynthesis caused by non-stomatal restriction. The 60 mg/L treatment had the most significant effect. The daily mean, peak, and trough values of P_n increased by 51.76%, 41.24%, and 64.47%, respectively. (4) Compared to the control, the chlorophyll fluorescence parameters F_v/F_m, F_v'/F_m', Φ_PSⅡ, and qP in each 6-BA treatment group increased to varying degrees during the experiment, while the NPQ value decreased. (5) The φ_Po, ψ_o, φ_Eo, E_ABS/CSm, E_TRo/CSm, E_ETo/CSm, and c_PIabs significantly increased, while φ_Do and E_DIo/CSm decreased with 6-BA treatment at an appropriate mass concentration (60 mg/L). These results indicated that the 6-BA treatment enhances the efficiency of PSⅡ light energy absorption, allocation, and utilization, as well as leaf-specific activity, alleviating the photoinhibition caused by excess excitation energy. 【Conclusion】 The 6-BA treatment at an appropriate mass concentration effectively enhances the antioxidant activity and photosynthetic performance of P. heterophylla leaves at the late growth stage, promoting growth and increasing root yield. The improvement in photosynthetic performance is related to enhancing antioxidant activity and PSⅡ photochemical activity in the leaves.