Weather is the immediate and local occurrence of such natural phenomena as temperature, light, rainfall, wind, and relative humidity. Climate is the pattern these phenomena assume day by day, week by week, month by month, and season to season, which is repeated annually in an area. If the area is small or near the ground surface it is called a microclimate.
Climate is determined by a location’s latitude, altitude, and relation to large bodies of water and land masses. Climatic factors are temperature, rainfall, light, and air movement. Each plant species is adapted to the climate in which it evolved. Some plants have a wide tolerance to climate conditions, other very intolerant of change.
Temperature. Most plants live and grow when the temperatures fall between 0oC and 50o C. however, the type of growth desired for the production of most crops falls in a much narrower range. That range can vary by crop. Some single-season crops do best in areas where there is a prolonged period of warm days and nights while other require cooler temperatures. Many perennial crops tolerate freezing or require a chilling period during the winter while others don’t tolerate freezing and chilling.
Rain/water. Plants are divided into three categories based on their water needs or tolerances. Xerophytes are those plants that have adaptation mechanisms enabling them to function with relatively less water than most other plants. Hydrophytes are those plants that thrive in or close to water. Mesophytes are the most common type and have water requirements and tolerances between the two extremes.
Light. Light quality, intensity, and duration all influence plant growth and crop productivity. Light quality affects photosynthesis, with red and blue being the most effective region light quality also affects plants photomorphogenically mainly through the relationship of red and fared light. Some plants including most field crops require relatively high light intensity. Others, such as coffee and many ornamental foliage plants, tolerate or require relatively low light intensity.
Air movement. Air movement in the field can be beneficial when it replenishes CO2 for rapidly photosynthesizing leaves. Likewise, it can be detrimental if it is too strong and at the wrong time of the production cycle.
Climatic factors influence the development and spread of disease and insects. Climatic factors that favor the development and spread of diseases and detrimental insects can negatively impact a crop, even if those factors favor crop growth.
In field crops temperature can be controlled or manipulated under some circumstances. To prevent or reduce injury from freezing, wind machines, heaters, mulches, row covers, or water sprinklers are used slightly raise the temperature in or near the plant. Wind damage can be lessened by the use of windbreaks. Irrigation is used to provide water when rainfall is insufficient. Row orientation and plant spacing can increase light penetration into a crop. Choosing species or varieties/cultivars that are adapted to an area improves crop productivity.
J.mcmahon, Margaret, et.al,. 2002. Hartman’s plant science. New Jersey: Pearson Eduction.