黄栌光合和呈色特性对重庆阴雨天气的响应

【目的】探讨重庆地区阳性植物黄栌的光合和呈色特性对当地阴雨天气的响应,为黄栌人工抚育提供科学依据。【方法】以黄栌为研究对象,于2019年4—11月定期监测(避开雨天)自然条件下控根容器内种植的4年生黄栌的光合特性、叶片色素含量、叶色参数等,并与2018年所测数据进行比较;收集2016—2019年重庆市气象数据,分析重庆地区2019年阴雨天气占比、降水量、日照时间、相对湿度等特征与2016—2018年的差异性,了解气象因子与黄栌叶片光合、呈色特性间的相关关系。【结果】2019年4—11月(黄栌生长期),重庆遭遇罕见的连绵阴雨天气,监测期超过半数时间为阴雨天气。相比2016—2018年,2019年日照时间减少10%~25%,最大日降水量增加30%~37%,平均降水量增加12.5%~25.0%,平均气温(Q)降低1%~2%。高湿、多雨、寡日照环境不利于黄栌光合色素合成,导致其净光合速率(P_n)降低,叶片呈色质量较差。相关性分析表明:P_n与日照时间(SD)和Q极显著正相关(P<0.01),与光合有效辐射(PAR)显著正相关(P<0.05),与日降水量≥0.1 mm天数(DPD)极显著负相关(P<0.01);蒸腾速率(T_r)与SD和Q极显著正相关(P<0.01),与PAR显著正相关(P<0.05),与DPD极显著负相关(P<0.01),与大气CO₂浓度(C_a)显著负相关(P<0.05)。叶绿素a(Chla)含量与Q显著正相关(P<0.05);花青素含量与DPD显著负相关(P<0.05)。叶色亮度(L^*)与叶绿素b(Chlb)含量极显著正相关(P<0.01),与Chla含量显著正相关(P<0.05);红/绿属性色相(a^*)与Chla、Chlb含量极显著负相关(P<0.01);其他色素含量与叶色参数间相关性均不显著(P>0.05)。a^*与T_r、P_n、气孔导度(G_s)极显著负相关(P<0.01);黄/蓝属性色相(b^*)与T_r、P_n、G_s极显著负相关(P<0.01);彩度(C^*)与T_r、P_n极显著负相关(P<0.01)与G_s显著负相关(P<0.05)。【结论】在2019年4—11月的连绵阴雨天气条件下,重庆地区黄栌表观量子效率(AQY)和P_n降低,利用弱光的能力和叶片呈色质量较差,但具有较宽的CO₂生态利用幅度与光照耐受范围,叶片Chlb含量的增加提高了对散射光的利用能力,从而增强对连绵阴雨天气的适应与耐受能力。研究结果可为我国黄栌引种栽培及科学管理提供参考。

Response of Cotinus coggygria photosynthesis and coloration to weather change in Chongqing

【Objective】The aim of this research is to study the effects of unusual continuous rainy weather on photosynthesis of Cotinus coggygria of Chongqing, and to investigate the responses in photosynthesis and color of the C. coggygria plant to weather changes so as to provide a scientific basis for artificial care of C. coggygria.【Method】 Local meteorological data in recent years were collected and analyzed to clarify the difference between the proportion of cloudy and rainy days, precipitation, sunshine duration, and the relative humidity in Chongqing in 2019 and those of recent years. In 2018, at the same time, N,P,K was used to examine the Cotinus coggygria leaf growth, photosynthesis, and the influence of color based on this research. In 2019 from April to November, monthly monitoring avoiding rainy days was undertaken as a control. This was undertaken under the conditions of natural root container planting for four years for Cotinus coggygria. The photosynthetic characteristics, the leaf blade pigment content, and the leaf color parameters were measured and compared with the data collected in 2018. The correlation between the meteorological factors, the photosynthetic characteristics, and the leaf color was analyzed.【Result】 In 2019, during the growing period for Cotinus coggygria from April to November, a rare rainy weather event was observed in Chongqing, and rainy weather was observed during more than half of the monitoring period. In 2019, compared with 2016-2018, the sunshine hours decreased by 10%-25%, the maximum daily precipitation increased by 30%-37%, the average rainfall increased by 12.5%-25.0%, and the average temperature decreased by 1%-2%. High humidity, high levels of rainfall, and an environment with low levels of sunshine is not conducive to Cotinus photosynthetic pigment synthesis. As a result, the net photosynthetic rate (P_n) decreased and the leaf color quality was found to be poor. The correlation analysis showed that P_n was significantly positively correlated with the sunshine duration (SD), temperature (Q) (P < 0.01), photosynthetically active radiation (PAR) (P < 0.05), and the daily precipitation ≥ 0.1 mm (DPD).The transpiration rate (T_r) was significantly positively correlated with SD and Q (P < 0.01), PAR (P < 0.05), DPD (P < 0.01), and the atmospheric carbon dioxide concentration (C_a) (P < 0.05). There was a significant positive correlation between the chlorophyll a (Chla) content and Q (P < 0.05). Anthocyanin content was negatively correlated with DPD (P < 0.5). The luminance (L^*) was significantly positively correlated with chlorophyll b (Chlb) content (P < 0.01) and was significantly positively correlated with the Chla content (P < 0.05). The red/green hue (a^*) was significantly negatively correlated with the contents of Chla and Chlb (P < 0.01). There was no significant correlation between the contents of other pigments and the leaf color parameters (P > 0.05). The a^*was significantly negatively correlated with T_r, P_n and G_s (P < 0.01). The yellow/blue hue (b^*) was significantly negatively correlated with T_r, P_n and G_s (P < 0.01). The chroma (C^*) was significantly negatively correlated with T_r and P_n (P < 0.01) and the stomatal conductance(G_s) (P < 0.05).【Conclusion】 Results from the study showed that for Cotinus coggygria under continuous wet weather conditions, while the apparent quantum efficiency (AQY) is reduced, the P_n is reduced, the ability to photosynthesize under low light levels is weak, and the leaf color quality is poor. However, in terms of CO₂, this taxon has a wide ecological amplitude and a wider tolerance range for illumination. By increasing the Chlb content, it improves their ability to use scattered light to adapt to poor weather conditions, supporting a strong tolerance to continuous rainy weather. These results can provide a reference for the introduction and cultivation of Cotinus coggygria and its scientific management in China.