Climate for Horticultural Crops

Climate plays a vital role in determining which crops are suitable for a specific region. It is the primary factor influencing plant growth and development. Understanding the climate of a region and how it interacts with the needs of different crops is crucial for optimizing production on a sustainable basis. Below is a detailed overview of the key climatic factors that affect horticultural crops:

Key Climatic Factors Affecting Horticultural Crops

Light:

• • Definition: Light is electromagnetic radiation that affects plant growth. Its wavelength ranges from 4000 to 7700 angstrom units. Light is essential for photosynthesis, which drives plant growth and development.
  • Aspects of Light:
    • Intensity: This refers to the brightness or strength of sunlight. It can be estimated by the number of hours of bright sunlight or by observing sky cloudiness. High light intensity is generally required for most horticultural crops.
    • Duration (Photoperiod or Day Length): The length of the day, from dawn to dusk, influences flowering and fruiting. Some plants are sensitive to the duration of light and can be classified into three categories:
      • Long Day Plants: Require longer daylight periods for flowering (e.g., cabbage, cauliflower, onion).
      • Short Day Plants: Require shorter daylight periods (e.g., strawberry, pineapple, chrysanthemum).
      • Day Neutral Plants: Not influenced by the length of day (e.g., tomato, pepper, cucumber).

Heat:

• • Definition: Heat refers to the non-mechanical transfer of energy due to a temperature difference between a system and its surroundings.
  • Importance for Plant Growth: Temperature plays a significant role in plant growth. The growth and development of plants depend on the availability of heat units, which are determined by the average temperature of a region.
  • Types of Heat Impact:
    • Chilling Requirements: Temperate fruit crops such as apples, pears, and peaches require chilling (cool temperatures) during their dormant phase to break dormancy. Excessive heat or frost can harm tropical and subtropical plants.
    • Heat Stress: Extremely high temperatures, such as those found in arid regions, can lead to wilting, sunscald, and necrotic spots, damaging or even killing plants.

Types of Climates for Horticultural Crops: Based on temperature and other climatic factors, the Earth’s surface is categorized into several climate zones, each supporting different types of crops:

• • Tropical Climate (Equable Climate):
    • This climate has no distinct winter and is warm throughout the year, with high humidity and rainfall.
    • Crops Suitable for Tropical Climate:
      • Mango, Banana, Papaya, Sapota, Pineapple, Coconut, Cashew, Arecanut, Breadfruit, Jackfruit, Avocado.
•  
  • Subtropical Climate:
    • Distinct seasons with a mild winter and hot summer.
    • Crops Suitable for Subtropical Climate:
      • Guava, Grape, Citrus, Date Palm, Phalsa, Pomegranate, Litchi, Loquat.
•  
  • Temperate Climate:
    • Features distinct winter, summer, and autumn, with freezing temperatures during winter.
    • Crops Suitable for Temperate Climate:
      • Apple, Pear, Peach, Plum, Almond.

Water and Air Requirements for Horticultural Crops

Water and air are vital factors in plant growth and are influenced by various environmental conditions. Understanding how these elements affect horticultural crops is crucial for achieving optimal growth and yield. Below is a detailed explanation of the role of water and air in horticulture:

Water:

Water is essential for the growth and development of plants. It is involved in key processes such as photosynthesis, nutrient and metabolite transport, and temperature regulation. Water is mainly provided through precipitation (rain and snow), and its availability varies depending on climate and region.

Key Points about Water for Plants:

Water Requirements:

• Water is essential for plant metabolism, photosynthesis, and maintaining plant structure.
• Water availability influences the types of crops that can be grown in a region. For instance, tropical and subtropical plants require consistent moisture, while temperate crops can tolerate drier conditions.

Water Availability in the Indian Subcontinent:

• In India, rainfall is primarily confined to June to September (the monsoon period), so fruit cultivation often requires supplemental irrigation during dry periods.
• The distribution of rainfall is more important than the total amount, as crops need water during the growing season to support fruit development.
• Regions with irregular rainfall patterns may have challenges in crop production, necessitating irrigation systems or the selection of drought-tolerant crops.

Humidity and Plant Growth:

• High Humidity: Favors crops like sapota, banana, mangosteen, jackfruit, and breadfruit, which thrive in moist conditions.
• Low Humidity: Plants such as ber, grape, date palm, pomegranate, citrus, aonla, and guava prefer drier conditions and are more tolerant of low humidity levels.

Impact of Humidity on Plant Growth:

• Low humidity increases the plant’s water requirements as it accelerates water loss through transpiration.
• High humidity can lead to the spread of fungal diseases, affecting plant health and reducing crop yield.

Precipitation and Its Influence on Water Availability:

• Areas near the equator typically receive higher annual rainfall (around 2000 mm), while regions farther from the equator experience less rainfall.
• Mountain ranges, proximity to oceans, and other geographic factors also influence the rainfall patterns in a region.

Air (Atmosphere):

Air, composed of oxygen, nitrogen, and other gases, is another essential climatic factor affecting plant growth. The quality and movement of air influence plant health and productivity.

Key Points about Air for Plants:

Air Quality and Pollution:

• Poor air quality, caused by pollutants such as hydrocarbons, sulfur dioxide (SO2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NO), and methane, can adversely affect plant growth.
• Pollutants like ethylene can also interfere with plant physiological processes, especially flower and fruit development.

Air Movement (Wind):

• Wind plays a crucial role in plant health by affecting transpiration rates and potentially causing physical damage to plants.
• Strong winds in regions like deserts, coastal areas, and valleys can cause severe damage to crops.
• Windbreaks and Shelterbelts: To protect crops from damaging winds, provisions like windbreaks and shelterbelts are used. These are rows of trees or shrubs planted around agricultural fields to reduce wind speed and protect plants.

Extreme Wind Events:

• Storms: Wind speeds of around 50 km/h can damage crops, especially young or delicate plants.
• Hurricanes: Winds over 100 km/h can cause catastrophic damage, uprooting trees and destroying crops. Wind protection and careful site selection are vital for plantations in hurricane-prone areas.

Seasonal Classification of Vegetable and Flower Crops

Vegetable and flower crops are classified into two main groups based on the season in which they thrive:

Warm Season Crops:

• Vegetables: Bottle gourd, watermelon, brinjal, tomato, cluster bean, okra, sweet potato, and radish.
• Flowers: Marigold, zinnia, chrysanthemum, sunflower, gomphrena, gaillardia, portulaca, kochia, amaranthus, celosia, coreopsis, calendula.

Cool Season Crops:

• Vegetables: Cabbage, cauliflower, pea, radish, tomato, beans, potato, onion, and carrot.
• Flowers: Aster, poppy, dianthus, dahlia, salvia, petunia, pansy, phlox, coreopsis, verbena, diamorphotheca.