Evaluation of an open portable chamber system for measuring cover crop water use in a vineyard and comparison with a mini-lysimeter approach

Cover crops are largely used in viticultural areas because of the many positive agronomic and environmental benefits they provide. However, there is insufficient data describing the amount of water they use. A portable chamber used as an open measurement system and its suitability to measure the cover crop evapotranspiration (E) in a vineyard are described in this study. The performance of the chamber was tested by a calibration experiment (R² = 0.97). The lowest air flow rate used (9.2 l s⁻¹) was found to be suitable to limit the chamber from overheating beyond 3.1 K above the outside temperature. Furthermore, an experiment was designed to compare the daily cover crop (Festuca arundinacea var. barfelix) water use measured by the chamber system with measurements using a mini-lysimeter (ML) method and with estimates using the FAO-56 PM equation (Eo). The experiment was carried out in one inter row of a vineyard over the course of 4 days following an irrigation event. Although the field experiment was limited to 4 days, the results obtained together with the calibration trials support the possibility of the chamber being a useful tool for measuring the cover crop E. The ability of the MLs to represent the water use of the cover crop in the rest of the vineyard was limited to the first two days of the experiment, after which time the soil water content inside the containers was significantly (p = 0.007, p = 0.03) lower than in the surrounding field.     

模块式垂直绿化植物在上海地区蒸散规律和节水灌溉研究

为指导节水灌溉,2010年在上海植物园利用微型蒸渗仪法研究了大花六道木、亮叶忍冬和红叶石楠在不同灌溉水平下的蒸散规律及植物长势。3种植物在不同的灌溉水平下月蒸散量和6～10月总蒸散量差异达到显著水平,说明不同的灌溉水平是影响植物蒸散的重要因素。测量、分析各种植物在4种灌溉水平下的生长和观赏指标,结合各个灌溉水平下的总蒸散量,灌溉水平3(即40%～100%最大持水量)和灌溉水平4(即25%～100%最大持水量)可以满足3种植物对水分的需求,并达到节水灌溉和减少养护的目的。