CROP COEFFICIENT, DRY MATTER PARTITION AND SEEDLINGS QUALITY OF Hymenaea courbaril L. IN CONTAINERS SIZES UNDER WATER DEFICIT IRRIGATION1

ABSTRACT Native species seedlings are commonly used in the degraded areas reforestation, riparian forests and legal reserve. Among the factors that influence the seedlings quality, are the container size and the substrate water availability. Thus, the objective of this paper was to evaluate Hymenaea courbaril L. seedlings response in function of irrigation levels and container sizes. The experiment was carried out in greenhouse, in randomized blocks design, with three replications in split plots, in 2 x 5 scheme. Rigid pots of 3.1 L and stiff plastic tubes of 4.0 L were used in the plots, while irrigation levels equals to 20%, 40%, 60%, 80% and 100% of the maximum evapotranspiration (ETm) were used in the subplots. The stiff plastic tube provided larger ETm and increased seedlings quality and, consequently, larger crop coefficient (Kc) in comparison with rigid pot, in the phase from 80 to 200 days after the sowing (DAS). The Kc of the seedlings in citrovase varired from 0.54 to 1.12, of the planting at 200 DAS, according the Penman-Monteith methodology. Irrigation levels between ETm 86.8% and 100% propitiated larger seedlings quality index. To the 200 DAS, the roots dry matter was larger than the leaves dry matter, unlike the initial phases.

摘要：乡土树种实生苗常用于退化区域造林、河岸林营建及法定保留地（legal reserve）的植被恢复工作。影响实生苗质量的关键因素包括容器规格与基质水分供给条件。本研究旨在探究孪叶豆（Hymenaea courbaril L.）实生苗对不同灌溉梯度与容器规格的响应规律。
试验于温室环境中开展，采用2×5裂区试验设计，设置3次重复。主区处理为两种容器：3.1升硬质花盆与4.0升硬质塑料管容器；副区处理为5个灌溉梯度，分别为最大蒸散量（maximum evapotranspiration, ETm）的20%、40%、60%、80%与100%。
试验结果表明，在播种后天数（days after sowing, DAS）80至200天的生长阶段内，相较于硬质花盆，硬质塑料管容器可提升实测蒸散量，改善实生苗质量，同时提高作物系数（crop coefficient, Kc）。采用Penman-Monteith模型（Penman-Monteith methodology）计算可知，播种后200天时，citrovase容器中实生苗的作物系数介于0.54至1.12之间。当灌溉梯度介于最大蒸散量的86.8%至100%时，可获得最优的实生苗质量指数。至播种后200天时，实生苗的根系干物质重量显著高于叶片干物质重量，这与生长初期的干物质分配模式截然相反。