十万个为什么·科学启蒙30篇（2）

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植物是如何‘知道’春天到了该开花的？

Plants sense seasonal changes using light, temperature, and internal biological clocks.
Special proteins in leaves detect how long nights last each day—a process called photoperiodism.
Many spring-blooming plants need long nights followed by warming temperatures to start flowering.
Cold winter temperatures break seed dormancy and reset growth timing in some species.
Hormones like florigen travel from leaves to buds to trigger flower development.
Genes switch on and off in response to environmental cues, controlling blooming time precisely.
Urban heat islands sometimes cause city trees to bloom earlier than rural ones.
Pollinators like bees also rely on these timing signals to find food when flowers open.
Climate change is disrupting this balance, causing mismatches between blooms and pollinators.
Scientists study plant genes to breed crops that flower reliably under changing conditions.