Climatic changes are already influencing the frequency, magnitude, and duration of extreme weathers (e.g. drought) in California. California is a leading state for vegetable production in United States (U.S.). Since vegetables are very sensitive to extreme weathers, it is critical to evaluate the effects of climate change on yield and to find the potential adaptive management strategies for the sustainable vegetable production. The objectives of this study were to develop a plant-oriented cropping model to evaluate the impacts of different cropping managements on yields under various climate condition and atmospheric CO2 levels. To improve modeling performance, numerous previous studies that reported broccoli yields in different managements were used. After model calibration and validation, 560 scenarios under the conditions of combinations of climate changes, four broccoli cultivars, five nitrogen fertilizer application rates, and four plant densities were simulated in two study locations in Monterey County, CA where produces almost 40% of total California broccoli production. Based on results from 33,600 simulations, broccoli yields were highly related to nitrogen fertilizer application. However, at high nitrogen rates (above 75 kg N ha−1), yields were barely changed. In general, under stressful conditions, all cultivars produced their maximum yields at low plant density, and their yields did not respond to addition of nutrient in soil. However, CO2 enrichment and warmer temperature under RCP8.5 pathways, yield responded positively with fertilizer application rate and plant density. It seems likely that the effects of cropping managements will depend upon CO2 level and temperature.

中文翻译：

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在不断变化的气候中优化西兰花生产的混合决策工具

气候变化已经在影响加利福尼亚极端天气（例如干旱）的频率、幅度和持续时间。加利福尼亚州是美国（美国）蔬菜生产的领先州。由于蔬菜对极端天气非常敏感，因此评估气候变化对产量的影响并寻找可持续蔬菜生产的潜在适应性管理策略至关重要。本研究的目的是开发一种以植物为导向的种植模型，以评估不同种植管理在不同气候条件和大气 CO2 水平下对产量的影响。为了提高建模性能，使用了许多先前报告不同管理中西兰花产量的研究。在模型校准和验证之后，在加利福尼亚州蒙特雷县的两个研究地点模拟了气候变化、四种西兰花品种、五种氮肥施用率和四种植物密度组合条件下的 560 种情景，该地区几乎占加州西兰花总产量的 40%。根据 33,600 次模拟的结果，西兰花产量与施氮肥高度相关。然而，在高施氮量下（高于 75 kg N ha-1），产量几乎没有变化。一般来说，在胁迫条件下，所有栽培品种在低植株密度下都能产生最大产量，而且它们的产量对土壤中养分的添加没有反应。然而，在RCP8.5途径下，CO2富集和温度升高，产量与施肥量和植物密度呈正响应。