Rojas-Jiménez Keilor, Holbrook Noel M, Gutiérrez-Soto Marco V
Programa de Ecofisiología de Plantas Tropicales, Estación Experimental Fabio Baudrit, Universidad de Costa Rica, Apartado 183-4050, Alajuela, Costa Rica.
Tree Physiol. 2007 Nov;27(11):1561-8. doi: 10.1093/treephys/27.11.1561.
Above- and belowground phenology and water relations of Enterolobium cyclocarpum Jacq. trees in the dry forest of Santa Rosa National Park, Costa Rica were studied during two consecutive phenological cycles, from November 1998 to June 2000. Aboveground phenological activity, including leaf shedding, growth and maturation of dormant fruits, new leaf flushing and flowering, occurred during the dry season. Measurements of leaf water potential, stomatal conductance and sap flow indicated that stomata of newly flushed leaves remained essentially closed until the onset of the first rains, suggesting that the main factor accounting for the favorable water balance of dry-season flushed leaves was their capacity to restrict water loss. Evidence of a contribution from stem and root water stores to shoot expansion was mixed because only the first dry-season flushing episode monitored was accompanied by a marked decrease in stem and root water potentials. Fine root production did not precede leaf flushing, occurred only after the onset of the rainy season and stopped under drought conditions, suggesting that soil water content was the most important variable controlling fine root dynamics in this species.
1998年11月至2000年6月的两个连续物候周期内，对哥斯达黎加圣罗莎国家公园干旱森林中的象耳豆树地上和地下物候以及水分关系进行了研究。地上物候活动，包括落叶、休眠果实的生长和成熟、新叶萌发和开花，均发生在旱季。叶片水势、气孔导度和液流测量结果表明，新萌发叶片的气孔在第一场雨来临之前基本保持关闭状态，这表明旱季萌发叶片水分平衡良好的主要因素是其限制水分流失的能力。关于茎和根的水分储存对新梢生长有贡献的证据并不一致，因为仅监测到的第一个旱季新梢萌发期伴随着茎和根水势的显著下降。细根生长并不先于叶片萌发，仅在雨季开始后发生，且在干旱条件下停止，这表明土壤含水量是控制该物种细根动态的最重要变量。
