Mexico holds the largest single bean production area in the world that is vulnerable to drought. Using field data and two future climate scenarios (RCP4.5 and RCP8.5) for the period 2020–2039, this study evaluated three common bean (Phaseolus vulgaris L.) cultivars planted under rainfed conditions at different densities in two locations in the north-central Mexican semi-arid temperate highlands. The sowing densities were 90,000, 145,000, and 260,000 plants ha⁻¹ established in single rows (SR), three rows (3R), and six rows (6R), respectively. The climate change scenarios were derived from an assembly model integrating 11 general circulation models (GCM) selected for Mexico with a 30” arc resolution. The baseline climate was for the period 1961–2010. The ALMANACMEX model (USDA-ARS-INIFAP, Temple, USA) was parameterized and evaluated and then re-run using the climate scenarios. Beans planted at 6R showed the highest increase in seed yield in both climate scenarios, although the response varied by cultivar and time periods. For the growth habit III cultivars, Flor de Mayo Bajio showed no difference in yield, while Pinto Saltillo, a drought-resistant cultivar, showed increases of 13% to 16% at 6R only until 2033. Growth habit I cultivar Azufrado 2 showed more than 60% increases at 6R in both climate scenarios for the full period 2020–2039. These results suggest that considering the projected climate conditions, high sowing densities may be a viable agronomic option for common bean production under rainfed conditions in semi-arid temperate regions, such as the highlands of Mexico, in the near future; however, the selection of the cultivar is a key element to consider in this regard.

中文翻译：

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未来气候变化下墨西哥半干旱高地雨养菜豆（Phaseolus vulgaris L.）的高播种密度

墨西哥是世界上最大的单一豆类生产区，易受干旱影响。利用实地数据和2020-2039年的两个未来气候情景（RCP4.5和RCP8.5），本研究评估了在北方两个地点以不同密度在雨育条件下种植的三种普通豆（菜豆）中部墨西哥半干旱温带高原。播种密度为90,000、145,000和260,000公顷ha ^-1分别以单行（SR），三行（3R）和六行（6R）建立。气候变化情景来自一个装配模型，该装配模型集成了为墨西哥选择的30弧分辨率的11个普通循环模型（GCM）。基准气候为1961–2010年。对ALMANACMEX模型（USDA-ARS-INIFAP，美国坦普尔）进行参数化和评估，然后使用气候情景进行重新运行。在6R下种植的豆在两种气候情景下均显示出最高的种子产量增幅，尽管其响应因品种和时期而异。对于生长习性III品种，Flor de Mayo Bajio的产量没有差异，而抗旱品种Pinto Saltillo仅在6R时才提高13％至16％，直到2033年。生长习性I品种Azufrado 2在2020–2039年的整个气候情景中，在6R时均表现出60％以上的增长。这些结果表明，考虑到预计的气候条件，在不久的将来，在半干旱的温带地区，例如墨西哥的高地，在雨育条件下，高播种密度可能是普通豆生产的可行农艺选择；然而，选择品种是这方面要考虑的关键因素。