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野生向日葵已在北美的南、西、北部地区相继发现,关于栽培种起源于北美何处,尚无定论。有的学者指出,向日葵属短日照植物,有可能起源于北美大陆的北纬20～52之间,有的报导,向日葵虽为短日照植物,一般对日照长短却不敏感,仅在日照特长的高纬度地区才有光周期反应;也有的资料介绍,向日葵长日照品种对长日照敏感,而短日照品种则对短日照敏感;更有的认为,向日葵已在世界各地不同的日照条件下种植多年,其光照特性已有所改变,有些品种属中性日照植物。为此,明确现有生产用种的光周期反应,是有理论与实践意义的。我们就此问题进行研究,现把1982年的试验结果,初报如下:
Wild sunflowers have been found in North, South, West and North America, but there is no conclusion as to where the cultivated species originated in North America. Some scholars pointed out that sunflower is a short-day plant, it may originate in the North American continent between latitudes 20 ~ 52, some reports, although sunflower short-day plants are generally not sensitive to the length of the sunshine, only sunshine specialty high Latitude regions have a photoperiodic response; some information, sunflower long-day varieties are sensitive to long-day sunshine, short-day varieties are short-day sensitive; more that the sunflower has been planted in different sunshine conditions around the world for many years, Its light characteristics have changed, some varieties are neutral sunshine plants. For this reason, it is of theoretical and practical significance to clarify the photoperiodic response of the current production species. We study this issue, the results of the 1982 test, the first report is as follows: