Temperature Requirements for Greenhouse Crops
(book excerpts)The most important environmental parameters that need to be controlled for optimal greenhouse climate are temperature, light, relative humidity, and carbon dioxide. Temperature is the most important single parameter in greenhouse controls as temperature has a significant role in many plant processes and attributes including seed germination, rooting, flowering, production time, plant architecture, and plant quality. Temperature primarily controls the rate of plant development (e.g., time to develop a leaf or time to flower). The ability to manage temperature more easily enables a grower to produce a crop that is marketable on a predetermined date. Proper temperature management requires an understanding of how temperature influences plant growth and development. Knowledge of how crops respond to temperature makes it possible to optimize the greenhouse environment so that production time is minimized, and crops are grown as efficiently as possible. The optimal temperature depends on the plant species grown and desired level of photosynthetic activity. Different crop species have different optimum growing temperatures and these optimum temperatures can be different for the root and the shoot environment and for the different growth stages during the life of the crop. Too high temperature reduces plant growth, eventually resulting in plant wilting and death whereas too low temperature limits plant growth. Typical greenhouse temperatures vary between 50 to 68 degrees F (10–20°C).
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Topics Within This Chapter:
- Cardinal Temperatures
- Cardinal Temperatures for Greenhouse Crops
- Minimum Temperature
- Optimum Temperature
- Maximum Temperature
- Cold-Tolerant, Cold-Temperate, and Cold-Sensitive Crops
- Growing Cold-Tolerant, Cold-Temperate, Cold-Sensitive Crops
- Temperature Requirements for Crop Growth Stages
- Temperature Influence of Plant Quality
- Plant Temperaure
- Root Zone Temperature
- Day/Night Temperature Differential (DIF)
- DIF’s Influence on Plant Height
- Side Effects of Negative DIF
- Limitations of Applying DIF
- Computer Control of DIF
- Average Daily Temperature for Greenhouse Crops
- Temperature Drop (DIP)
- Water Vapor-Pressure Deficit (VPD)
- Temperature and Daily Light Integral (DLI)