What Plant To Choose For Hydroponic?

Not all crops are appropriate for HYDROPONICS or CONTROLLED ENVIRONMENT AGRICULTURE (CEA). The reason: ECONOMICS
Both hydroponics and CEA (e.g., shade and greenhouses, etc.) cost money. Therefore, the crops chosen must yield a high enough monetary return to justify the expense. In the U.S and most European countries the typical crops that are grown using hydroponics include:

• TOMATOES (mainly beefsteaks and TOV’s – tomatoes on the vine)
• COLORED BELL PEPPERS (mainly yellows or goldens, also oranges, reds)
• LONG CUCUMBERS (also known as English, European, Seedless or Burpless)
• LETTUCE (several crops can be grown per year in hydroponics/CEA)
• SPECIALTY SALAD GREENS MEDICINALS (especially root crops grown using “aeroponics” where the roots can be harvested without destroying the whole plant – mainly in research)

In most Asian countries like Malaysia, Thailand, Japan, Taiwan and Korea however, the typical crops that are grown using hydroponics include:

• MUSK MELONS
  
• CAPSICUM
• JAPANESE CUCUMBER
  
• CHILLIES
• TOMATOES

Other crops that are grown using some form of CEA or protected agriculture include:

1. FOLIAGE PLANTS (usually require shade and humidity – as in the jungles from which they come)
2. FLORAL CROPS (including cut flowers, i.e., mums or carnations, and potted plants i.e., roses, etc.)
3. CERTAIN “ROW” CROPS (can be planted outside in colder climates using plastic tunnels (row covers) for protection against the cold)
   

We will concentrate on tomatoes with brief discussions of other crops (mainly vegetables) grown in hydroponics.

SOME BASIC PLANT ANATOMY
Flowering plants are composed of TWO MAJOR SYSTEMS: SHOOTS AND ROOTS.
THE SHOOTS:
*Grow up in response to gravity AND will grow toward a light source.
*Bear the leaves, flowers and fruit.
*The leaves usually contain pigments and are the sites of photosynthesis.
*The leaves also contain stomata, pores in the leaf through which water exits and through which gas exchange occurs (carbon dioxide in and oxygen out).
*Leaves attach to the stem = NODE; the stem in between nodes = INTERNODE
*Flowers or clusters of flowers are usually produced at regular intervals.

THE ROOTS:
*Grow down in response to gravity.
*Act to ANCHOR the plant in the growing medium.
*Absorb water, mineral nutrients and oxygen.
*Classified as tap or fibrous. Submerged roots may not develop root hairs.
*Storage organs (carbohydrates, etc.); site of synthesis alkaloids, hormones, etc.)

SHOOTS AND ROOTS: CONNECTED BY VASCULAR TISSUE: The XYLEM carries water and mineral nutrients from the roots to the leaves, flowers and fruits. The PHLOEM mainly carries photosynthates, the products of photosynthesis, from the leaves (the “source” of photosynthesis) to various “sinks” (apical meristem, fruit, roots, etc.) The CAMBIUM separates the xylem and phloem. It is the growing layer that produces new xylem to the inside and new phloem to the outside of the stem.

THE LEAVES: THE PRIMARY SITE OF PHOTOSYNTHESIS:
(though any green tissue is usually photosynthetic).
A typical leaf is covered on both sides by the EPIDERMIS. The epidermis is covered by a waxy CUTICLE. Interior to the epidermis on the upper side are the PALISADE PARENCHYMA cells. These are where photosynthesis takes place. Interior to the epidermis on the lower side are the
SPONGY MESOPHYLL cells. These create an air space for gas exchange. Mainly on the lower leaf surface are pairs of cells, called GUARD CELLS, that form openings, STOMATA, through which gas exchange takes place.