PLANTS
PLANT REPRODUCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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In the summer when days are long and Pfr is high
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In the winter when days are short and Pfr is high
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In the winter when days are short and Pfr is low
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In the winter when days are long and Pfr is high
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Detailed explanation-1: -Many spring-and fall-flowering plants are short-day plants, including chrysanthemums, poinsettias and Christmas cactus. If these are exposed to more than 12 hours of light per day, bloom formation does not occur. Other plants require only a short night to flower. These are termed “long-day” plants.
Detailed explanation-2: -Poinsettias (Euphorbia pulcherrima) are popular winter houseplants because they flower in mid-winter, and because their beauty is the result of bracts (persistent colored leaves) instead of flowers, their attractiveness is long-lasting.
Detailed explanation-3: -So, flowering starts to be initiated starting at fall solstice (that would be September 22 in the Northern Hemisphere this year). Flowering actually begins after about two months of this short-day treatment, about a month before Christmas.
Detailed explanation-4: -Fall Care and Re-blooming Phase To re-flower your poinsettia, you must keep the plant in complete darkness between 5pm and 8am daily from the end of September until color shows in the bracts (early to mid-December). The temperature should remain between 60 and 70 degrees F.