Relationship between heteromorphic leaf traits of Populus euphratica and its individual development

ObjectiveLeaf is the most adaptable plant organ responding to the environment. Leaf structure influences plant physiological processes, such as photosynthesis. Thus, it is extremely important to understand the changes in leaf structure and underly factors for exploring the strategy of plant adaptation.

MethodTo detect the relationship between the leaf structural traits of Populus euphratica and its individual development stage, we investigated the leaf length and width of P. euphratica to calculate leaf shape changes during reproduction and non-reproduction period at different ages in Ejina artificial P. euphratica forest of Inner Mongolia.

ResultThe results showed that the leaf length and the ratio of leaf length to leaf width decreased with increasing tree age, while the leaf width increased. Tree age accounted for 53.1%, 38.6% and 66.1% of variations in the leaf length, leaf width and the ratio of leaf length to width, respectively. The leaf shape changes were significantly influenced by reproduction period. Leaf length and ratio of the length to width in reproduction period were significantly smaller while leaf width was larger than those in non-reproduction period. However, the leaves of P. euphratica during non-reproduction period gradually changed from lanceolate to broad-ovate with increased tree age. The DBH was significantly correlated with the leaf traits, which was negatively correlated with the leaf length and the ratio of leaf length to leaf width versus positively correlated with the leaf width. The DBH accounted for most of the variations in the leaf traits by one-dimensional regression analysis (R²>0.5, P < 0.000 1). But DBH accounted for a lower portion of the overall variations of leaf traits based on multiple linear models (leaf length 8.6%, leaf width 13.1%, the ratio of leaf length to width 3.4%). Furthermore, we detected significant interactive effects between DBH and age on the leaf traits.

ConclusionIn conclusion, the leaf traits of P. euphratica were significantly correlated with the tree growth and development. The leaf shape changed from lanceolate to broad-ovate with tree growth to adapt the desert environment. We infer P. euphratica accelerates the leaf shape changes to provide sufficient energy for reproduction which may be an adaptive strategy of P. euphratica to environmental conditions.