The management of orthotropic stems modulates the photosynthetic performance and biomass allocation of productive plants of Arabica coffee

ABSTRACT Due to the possibility of enhancing the physiological responses by modulating the architecture of coffee trees, the objective of the study was to analyze the leaf gas exchanges and biomass allocation of Arabica coffee cultivated with different numbers of orthotropic stems. The experiment was carried out in a plantation located in Santa Teresa-ES, Brazil, cultivated with spacing of 2.5×1.0 m, using the cultivar Catuaí Vermelho IAC44. The gas exchange rates were monitored along stages of the phenological cycle (2014/2015), following a split-plot scheme, 3×3 (number of orthotropic stems per plant in three levels: 1, 2 and 3; and the phenological stages in three levels: flowering, fruit formation and maturation). The allocation of biomass in the plagiotropic branches was also analyzed during the phenological stage of fruit maturation. The management of the number of orthotropic stems affected the photosynthetic responses and biomass allocation of coffee trees. Under the studied conditions, cultivating the plants with two orthotropic stems created conditions which promoted the photosynthetic responses. Keeping more stems promotes the availability of leaves per amount of produced fruits in the plagiotropic branches, allowing the plant to sustain the production with less metabolic wearing.

摘要
鉴于通过调控咖啡树株型可增强其生理响应，本研究旨在分析不同直立茎（orthotropic stem）数量下栽培的阿拉比卡咖啡（Arabica coffee）的叶片气体交换与生物量分配特征。本试验于巴西圣特雷莎-圣埃斯皮里图州（Santa Teresa-ES）的种植园开展，种植株行距为2.5×1.0 m，供试品种为卡特杜伊红果IAC44（Catuaí Vermelho IAC44）。本试验采用3×3裂区试验设计（split-plot scheme），于2014/2015年的物候周期（phenological cycle）内监测叶片气体交换速率：主区因素为单株直立茎数量（设1、2、3三个水平），副区因素为物候阶段（设开花、坐果、成熟三个水平）。本研究还于果实成熟的物候阶段，分析了斜生枝（plagiotropic branch）的生物量分配情况。直立茎数量的调控显著影响咖啡树的光合响应（photosynthetic responses）与生物量分配格局。在本试验设置的条件下，单株保留2条直立茎可显著提升光合响应水平。保留更多直立茎可提升斜生枝上单株果实产量对应的叶片供给量，使植株能够以更低的代谢损耗维持生产能力。