开花红哺鸡竹叶片的显微结构与光响应参数研究

Microstructure and Light-response Parameters of Flowering Bamboo( Phyllostachys iridescens) Blades

为阐释竹子开花过程中的生理功能变化,探寻竹子花后复壮更新的途径,本研究选取红哺鸡竹(Phyllostachys iridescens)竹林换叶后出现开花征兆的竹株异形叶和外观正常叶,并以未开花竹株正常叶为对照,进行了叶片结构观察和光响应测定。结果发现:红哺鸡竹从营养生长向生殖生长转变的过程中,叶片的发育有变小变薄的特征,相邻维管束距离增大,维管束横切面积和气孔密度有显著变小的趋势(p<0.05)。开花竹异形叶的叶片厚度、上表皮厚度、维管束横切面积和气孔密度是未开花竹正常叶的71.59%、87.40%、77.79%和73.56%,相邻维管束距离增加了19.34%,这种结构的变化相应地导致了开花竹叶片光合和蒸腾作用的显著降低(p<0.05)。开花竹异形叶的光响应参数,如光饱和点、表观量子效率和最大光合速率是未开花竹正常叶的67%、40.5%和8.27%,分别为900、0.015、1.22μmol·m-2·s-1;光补偿点比未开花竹正常叶高出208.5%,达85.11μmol·m-2·s-1,而开花竹外观正常叶的光响应参数介于两者之间。开花竹株的叶片结构弱化和随之产生的生理功能异化可能是多年生竹子无法像树木那样连年开花、持续生长的重要原因之一。

To study the physiological function changes during bamboo flowering, and explore the methods of rejuvenation after flowering, we selected different Phyllostachys iridescens nonflowering bamboo blades, heteromorphic blades and normal blades from flowering bamboo stands, and observed their anatomical structures and photosynthetic parameters. Results showed that during the phase change from vegetative to reproductive growth, the blades of flowering bamboo appeared smaller and thinner and the distance between adjacent vascular bundles tended to increase, while the vascular bundle transverse area and stomatal density decreased. The overall thickness, upper epidermis thickness, vascular bundle transverse area and stomatal density of the heteromorphic blades were 71.59%, 87.40%, 77.79% and 73. 56% that of the non-flowering bamboo blades, respectively, while the distances between adjacent vascular bundles were 19. 34% larger than that of non-flowering bamboo blades, leading to reductions in photosynthesis and transpiration of flowering bamboo blades. Lightresponse parameters such as the light saturation point, apparent quantum yield, and maximum photosynthetic rates of heteromorphic blades were 67%, 40. 5% and 8.27% that of non-flowering blades, respectively, 900, 0.015 and 1.22 μmol· m^-2· s^-1, and the light compensation point of the heteromorphic blades （85.11 μmol · m^-2· s^-1 ） was 208.5% higher than that of non-flowering blades. However, the light-response parameters of normal blades of flowering bamboo were somewhere in between. The weakened leaf structure and function alienation exacerbated by the flowering bamboo eventually led to perennial bamboos, which could not grow normally after flowering.