Louarn Gaëtan, Guedon Yann, Lecoeur Jeremie, Lebon Eric
INRA, Montpellier SupAgro, UMR759 LEPSE, 2 place Viala, F-34060 Montpellier, France.
Ann Bot. 2007 Mar;99(3):425-37. doi: 10.1093/aob/mcl276. Epub 2007 Jan 4.
Plant architecture and its interaction with agronomic practices and environmental constraints are determinants of the structure of the canopy, which is involved in carbon acquisition and fruit quality development. A framework for the quantitative analysis of grapevine (Vitis vinifera) shoot architecture, based on a set of topological and geometrical parameters, was developed for the identification of differences between cultivars and the origins of phenotypic variability.
Two commercial cultivars ('Grenache N', 'Syrah') with different shoot architectures were grown in pots, in well-irrigated conditions. Shoot topology was analysed, using a hidden semi-Markov chain and variable-order Markov chains to identify deviations from the normal pattern of succession of phytomer types (P0-P1-P2), together with kinematic analysis of shoot axis development. Shoot geometry was characterized by final internode and individual leaf area measurements.
Shoot architecture differed significantly between cultivars. Secondary leaf area and axis length were greater for 'Syrah'. Secondary leaf area distribution along the main axis also differed between cultivars, with secondary leaves preferentially located towards the basal part of the shoot in 'Syrah'. The main factors leading to differences in leaf area between the cultivars were: (a) slight differences in main shoot structure, with the supplementary P0 phytomer on the lower part of the shoot in 'Grenache N', which bears a short branch; and (b) an higher rate and duration of development of branches bearing by P1-P2 phytomers related to P0 ones at the bottom of the shoot in 'Syrah'. Differences in axis length were accounted for principally by differences in individual internode morphology, with 'Syrah' having significantly longer internodes. This trait, together with a smaller shoot diameter, may account for the characteristic 'droopy' habit of 'Syrah' shoots.
This study highlights the architectural parameters involved in the phenotypic variability of shoot architecture in two grapevine cultivars. Differences in primary shoot structure and in branch development potential accounted for the main differences in leaf area distribution between the two cultivars. By contrast, shoot shape seemed to be controlled by differences in axis length due principally to differences in internode length.
植株架构及其与农艺措施和环境限制因素的相互作用是冠层结构的决定因素，而冠层结构与碳获取和果实品质发育相关。基于一组拓扑和几何参数，开发了一个用于定量分析葡萄（Vitis vinifera）新梢架构的框架，以识别品种间的差异以及表型变异的来源。
将两个具有不同新梢架构的商业品种（“歌海娜N”、“西拉”）种植在花盆中，并保持充分灌溉。使用隐半马尔可夫链和可变阶马尔可夫链分析新梢拓扑结构，以识别与叶序类型（P0 - P1 - P2）正常 succession 模式的偏差，同时对新梢轴发育进行运动学分析。通过测量最终节间长度和单叶面积来表征新梢几何形状。
品种间新梢架构存在显著差异。“西拉”的二级叶面积和轴长更大。两个品种二级叶面积沿主轴的分布也不同，“西拉”的二级叶优先位于新梢基部。导致品种间叶面积差异的主要因素有：（a）主梢结构存在细微差异，“歌海娜N”新梢下部有额外的P0叶序，其上着生短枝；（b）“西拉”中与新梢基部P0叶序相关的P1 - P2叶序所生枝条的生长速率和持续时间更高。轴长差异主要由单个节间形态差异引起，“西拉”的节间明显更长。这一特征以及较小的新梢直径，可能解释了“西拉”新梢特有的“下垂”习性。
本研究突出了两个葡萄品种新梢架构表型变异所涉及的架构参数。主梢结构和枝条发育潜力的差异是两个品种叶面积分布主要差异的原因。相比之下，新梢形状似乎主要由轴长差异控制，而轴长差异主要源于节间长度差异。
