川南城市园林中紫薇开花物候变化特征及其影响因素

Variation characteristics and the impact factors of flowering phenology of Lagerstroemia indica in urban gardens in south Sichuan

为了明确城市园林中紫薇(Lagerstroemia indica)开花物候的变化特征,探讨花期影响因素和指导开花植物配置,对川南城市园林栽培的紫薇植株进行定期观测,记录了紫薇的2011—2014年开花物候,分析个体、群体水平上物候事件的差异以及植株大小和气候因子的影响。结果表明:紫薇个体在6月初至9月中旬进入花期,末花期多在10月,花期持续8~137 d,具有60~90 d花期的植株比例最高;不同年份开花植株比例和物候特征存在一定差异,种群水平花期持续时间最短为2014年的106 d,最长为2012年的130 d;但开花植株数量的时间格局总体相似,始花期与花期持续时间之间相关性显著;基径显著影响紫薇的开花物候特征,较大的植株往往开花较早,并且具有更长的花期;紫薇的盛花期多集中在7—9月;开花植株数量与前一个月的平均气温呈显著正相关,与同期温度、降雨量相关性不显著;紫薇开花物候在气候因子影响下年际间存在明显差异,也表现出一定规律性格局;园林中多样化的个体物候有利于维持群体水平上花期的观赏性,选择大植株可获得较稳定的观赏效果。

To clarify the variation characteristics of flowering phenology of Lagerstroemia indica in urban gardens, to explore factors impacting its flowering phases and to provide guidance to disposition in planting, cultivated individuals of the species in southern Sichuan were observed every week in 2011-2014. The difference of phenological events was analyzed at individual level and population level, and the effects of plant size and weather factors on flowering phenology were also discussed. The results showed that the period of flowering at individual level began in early June to middle September and ended in October, lasting for 8-137 d, and most individuals had a 60-90 d flowering duration. The proportion of blooming plants and the phonological characteristics varied in different years. The shortest duration of flowering was 106 d in 2014, while the longest duration was 130 d in 2012. Similar temporal pattern of flowering plant number was recorded in different years, and the first flowering phase was significantly correlated to flowering duration. Basal diameter had a significant effect on flowering phenology. The individuals with big size bloomed earlier and lasted for longer time. Peak flowering phase of L. indica often occurred from July to September. The number of flowering individuals was positively correlated to the average air temperature in previous month, but had no significant correlation to current air temperature and rainfall. Being affected by weather and other factors, flowering phenology differed obviously among various years, showing some regular patterns as well. Diversified flowering phenology at individual level was beneficial to maintaining high ornamental value at population level, and selection of big size plants in gardens could obtain stable flowering effects.