DIF is defined as what?

• A. The difference between day and night temperatures
• B. The difference between daylight length and temperature
• C. The difference between night and day temperatures, affecting growth
• D. The difference between humidity and soil moisture

Answer: (C)

Understanding how the difference between day and night temperatures affects plant growth. DIF is the difference between day and night temperatures, and that difference influences how much plants elongate. When daytime temperatures are higher than nighttime temperatures (positive DIF), plants tend to stretch more and grow taller. If nighttime temperatures are higher than daytime temperatures (negative DIF), growth slows and plants become more compact. When day and night temperatures are the same (zero DIF), growth is more uniform with less elongation. Growers use this pattern to tune plant height by adjusting day and night temperatures. So the concept described is the difference between night and day temperatures, and how that difference impacts growth, rather than differences in daylight length or in humidity.