Wang Jinfeng, Almutairi Bader O, Wang Lin, Shi Peijian, Yao Weihao, Niinemets Ülo
Co-Innovation Centre for Sustainable Forestry in Southern China, Bamboo Research Institute, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China.
College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
AoB Plants. 2024 Sep 25;16(5):plae054. doi: 10.1093/aobpla/plae054. eCollection 2024 Oct.
Cotyledons play an important role in early seedling establishment. However, relative to primary leaves, cotyledons tend to have a different investment-on-return strategy. To detect the potential differences in the mass () versus area () scaling relationships between cotyledons and primary leaves in different light environments, a total of 75 seedlings were sampled at an open site ( = 52; light availability: 74 ± 5 %) and a shaded site ( = 23; light availability: 4.2 ± 1.2 %). Reduced major axis regression protocols were used to fit the versus scaling relationships of primary leaves and cotyledons. The bootstrap percentile method was used to test the significance of the differences in the scaling exponents of versus between the two light environments. The scaling exponents of cotyledons at both two sites, as well as the primary leaves at the shade site, were greater than unity indicating 'diminishing returns', while the scaling exponent of primary leaves at the open site was smaller than unity indicating 'increasing returns'. The data collectively indicated light-dependent shifts in support investments and differences in the function of cotyledons and primary leaves. Average leaf structural traits displayed significant differences between the two light environments in accordance with the premium in enhancing photosynthetic capacity in high light and light interception in low light. Although the trait responses to light availability were similar for primary leaves and cotyledons, primary leaves were more responsive to light availability, indicating lower plasticity of cotyledons in response to light levels. These results advance our understanding of the roles of cotyledons and primary leaves in the life history of seedlings in different forest light environments.
子叶在幼苗早期建立过程中发挥着重要作用。然而，相对于初生叶，子叶往往具有不同的投入-回报策略。为了检测不同光照环境下子叶和初生叶在质量（）与面积（）缩放关系上的潜在差异，在一个开阔地（=52；光照可用性：74±5%）和一个遮荫地（=23；光照可用性：4.2±1.2%）共采集了75株幼苗样本。采用主轴回归协议来拟合初生叶和子叶的与缩放关系。使用自助百分位数法来检验两种光照环境下与缩放指数差异的显著性。两个地点的子叶以及遮荫地的初生叶的缩放指数均大于1，表明“收益递减”，而开阔地初生叶的缩放指数小于1，表明“收益递增”。这些数据共同表明了支持投资的光依赖性变化以及子叶和初生叶功能的差异。根据在高光下提高光合能力和在低光下拦截光线的优势，两种光照环境下的平均叶片结构特征存在显著差异。虽然初生叶和子叶对光照可用性的性状反应相似，但初生叶对光照可用性更敏感，表明子叶对光照水平的可塑性较低。这些结果推进了我们对不同森林光照环境下子叶和初生叶在幼苗生活史中作用的理解。
