Embrapa Informática Agropecuária, Campinas, SP, Brazil.
Embrapa Environment, Campinas, SP, Brazil.
Ann Bot. 2018 Jun 28;122(1):117-131. doi: 10.1093/aob/mcy042.
Dynamics in branch and leaf growth parameters, such as the phyllochron, duration of leaf expansion, leaf life span and bud mortality, determine tree architecture and canopy foliage distribution. We aimed to estimate leaf growth parameters in adult Arabica coffee plants based on leaf supporter axis order and position along the vertical profile, considering their modifications related to seasonal growth, air [CO2] and water availability.
Growth and mortality of leaves and terminal buds of adult Arabica coffee trees were followed in two independent field experiments in two sub-tropical climate regions of Brazil, Londrina-PR (Cfa) and Jaguariúna-SP (Cwa). In the Cwa climate, coffee trees were grown under a FACE (free air CO2 enrichment) facility, where half of those had been irrigated. Plants were observed at a 15-30 d frequency for 1 year. Leaf growth parameters were estimated on five axes orders and expressed as functions of accumulated thermal time (°Cd per leaf).
The phyllochron and duration of leaf expansion increased with axis order, from the seond to the fourth. The phyllochron and life span during the reduced vegetative seasonal growth were greater than during active growth. It took more thermal time for leaves from the first- to fourth-order axes to expand their blades under irrigation compared with rainfed conditions. The compensation effects of high [CO2] for low water availability were observed on leaf retention on the second and third axes orders, and duration of leaf expansion on the first- and fourth-order axes. The second-degree polynomials modelled leaf growth parameter distribution in the vertical tree profile, and linear regressions modelled the proportion of terminal bud mortality.
Leaf growth parameters in coffee plants were determined by axis order. The duration of leaf expansion contributed to phyllochron determination. Leaf growth parameters varied according the position of the axis supporter along the vertical profile, suggesting an effect of axes age and micro-environmental light modulations.
分支和叶片生长参数的动态变化，如叶间隔期、叶片扩展持续时间、叶片寿命和芽死亡率，决定了树木的结构和冠层叶片的分布。我们旨在根据叶支轴的顺序和在垂直剖面中的位置来估算成年阿拉比卡咖啡植株的叶片生长参数，同时考虑与季节性生长、空气[CO2]和水分供应有关的变化。
在巴西两个亚热带气候区的两个独立田间试验中，对成年阿拉比卡咖啡树的叶片和顶芽的生长和死亡进行了跟踪。在 Cwa 气候下，咖啡树在 FACE（自由空气 CO2 富集）设施下生长，其中一半进行了灌溉。在一年的时间里，每隔 15-30 天对植物进行观察。在五个轴序上估算了叶片生长参数，并表示为累积热时间（每片叶的°Cd）的函数。
叶间隔期和叶片扩展持续时间随轴序的增加而增加，从第二到第四。在减少的营养季节性生长期间，叶间隔期和寿命大于活跃生长期间。在灌溉条件下，与雨养条件相比，来自第一至第四轴序的叶片需要更多的热时间来展开叶片。高[CO2]对低水分可用性的补偿效应表现在第二和第三轴序上的叶片保留率，以及第一和第四轴序上的叶片扩展持续时间上。二阶多项式模型化了叶片生长参数在垂直树木剖面中的分布，线性回归模型化了顶芽死亡率的比例。
咖啡植株的叶片生长参数由轴序决定。叶片扩展持续时间有助于叶间隔期的确定。叶片生长参数根据轴支的位置沿垂直剖面而变化，这表明轴年龄和微环境光照调制的影响。
