This study evaluates the response of maize growing cycle length to meteorological variables at regional scale particularly, in the short-term period, considering global climate change. The experiment was carried out in Veneto Region (Northeast Italy) where maize phenological data collected by the regional network from 2005 to 2007 were combined with temperature data to analyse the relationship between BBCH stages and thermal sum. The effects of climatic changes in the near and medium term on maize phenology and on water requirements were also evaluated over a grid of climatic data obtained from different climatic models. The piecewise analysis gave the best fitting between BBCH and Growing Degree Days observed data characterized by two lines with different slopes with BBCH 70 (beginning of fruit development) as changing stage. The angular coefficient of the first line was 2.6 times than the second one (0.028) suggesting that the early stages of the growing cycle are more sensitive to air temperature. The simulation of maize phenology evolution highlights a modest variation at the 2020-time horizon, while an expected reduction of maize growing cycle of about 10 days has been estimated for 2030-time horizon. Long-term phenological observation are desirable to confirm our findings and to improve the strength of dataset.

中文翻译：

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短期气候变化对意大利东北部玉米物候期的影响

本研究评估了玉米生长周期长度对区域尺度气象变量的响应，特别是在短期内，考虑到全球气候变化。该试验在威尼托地区（意大利东北部）进行，该地区网络从 2005 年到 2007 年收集的玉米物候数据与温度数据相结合，分析了 BBCH 阶段与热量总量之间的关系。近期和中期气候变化对玉米物候和需水量的影响也通过从不同气候模型获得的气候数据网格进行了评估。分段分析给出了 BBCH 和生长度日观察数据之间的最佳拟合，其特征是两条具有不同斜率的线，以 BBCH 70（果实发育的开始）为变化阶段。第一条线的角系数是第二条线的 2.6 倍 (0.028)，表明生长周期的早期阶段对气温更敏感。玉米物候进化的模拟突出了 2020 年时间范围内的适度变化，而估计 2030 年时间范围内玉米生长周期预计减少约 10 天。需要长期物候观察来证实我们的发现并提高数据集的强度。而预计到 2030 年的时间范围内，玉米生长周期预计会减少约 10 天。需要长期物候观察来证实我们的发现并提高数据集的强度。而预计到 2030 年的时间范围内，玉米生长周期预计会减少约 10 天。需要长期物候观察来证实我们的发现并提高数据集的强度。