Kuang Qiyu, Su Shiying, Hu Liang
School of Geography and Planning, Sun Yat-sen University, Guangzhou, China.
Front Plant Sci. 2024 Oct 4;15:1425949. doi: 10.3389/fpls.2024.1425949. eCollection 2024.
The proliferation of vigorous lianas usually forms liana canopies over the crowns of host trees and liana mats on the ground of open areas or large forest gaps. While research on liana canopies has increased significantly in recent decades, our understanding of liana mats remains limited. (Convolvulaceae), a fast-growing liana, forms mature liana mats that can persist for decades, characterized by numerous upright searcher shoots that extend from the liana mats in search of supports. However, the reasons behind the proliferation of these searchers, as well as their growth and branching patterns in mature liana mats that lack support, are not well understood. We hypothesize that searchers are an inevitable phase in the growth rhythm of within these mature liana mats. We tested our hypothesis by tracking the lifespan and status of searchers during the early, middle, and late periods of the year. Our findings reveal the following: (1) searchers exhibit apical dominance and have a short lifespan; over 95% of searchers lost their terminal buds within two months during the early period, while it took only one month during the middle and late periods. (2) The original lateral buds of the searchers also have a limited lifespan, yet the nodes can sprout new lateral buds after the loss of their originals. (3) With the withering of terminal buds, the total number of lateral shoots decreased, while the quantity of long lateral shoots (≥ 50 cm) and their elongation rates increased. (4) Each surviving segment of a searcher typically develops one or two long lateral shoots, none of which grow into searchers. We conclude that the shoots of in mature liana mats periodically alternate between searchers and stolons, collectively forming a zigzag branching system. The high rate of lateral bud resprouting may facilitate the rapid recovery of mature liana mats early in the year, while the reduced lifespan of searchers and limited number of long lateral shoots represent effective strategies for , balancing the investment and risk associated with foraging in mature liana mats.
活力旺盛的藤本植物大量繁殖，通常会在寄主树冠上方形成藤本冠层，并在开阔区域或大型林窗的地面上形成藤本草甸。尽管近几十年来对藤本冠层的研究显著增加，但我们对藤本草甸的了解仍然有限。（旋花科）是一种生长迅速的藤本植物，能形成可存续数十年的成熟藤本草甸，其特征是有许多直立的探索性嫩枝从藤本草甸中延伸出来寻找支撑物。然而，这些探索性嫩枝大量繁殖的背后原因，以及它们在缺乏支撑的成熟藤本草甸中的生长和分枝模式，目前还不太清楚。我们假设探索性嫩枝是这些成熟藤本草甸生长节律中不可避免的一个阶段。我们通过跟踪一年中早、中、晚三个时期探索性嫩枝的寿命和状态来验证我们的假设。我们的研究结果表明：（1）探索性嫩枝表现出顶端优势且寿命较短；在早期，超过95%的探索性嫩枝在两个月内失去顶芽，而在中期和后期仅需一个月。（2）探索性嫩枝的原侧芽寿命也有限，但节点在原侧芽失去后能萌发出新的侧芽。（3）随着顶芽枯萎，侧枝总数减少，而长侧枝（≥50厘米）的数量及其伸长率增加。（4）每个存活的探索性嫩枝段通常会长出一到两个长侧枝，没有一个会长成探索性嫩枝。我们得出结论，成熟藤本草甸中的嫩枝会在探索性嫩枝和匍匐茎之间周期性交替，共同形成一个之字形分枝系统。侧芽的高再发芽率可能有助于成熟藤本草甸在年初迅速恢复，而探索性嫩枝寿命的缩短和长侧枝数量的有限代表了有效的策略，平衡了在成熟藤本草甸中觅食的投资和风险。
