The most common form of soilless culture is hydroponics. It consists of growing plants in a well aerated substrate with high water retention and frequent circulation of a water and nutrient solution to meet the needs of the plants. The substrates frequently used for this method of production are Rockwool, coconut fiber, expanded clay balls, sphagnum peat moss, and perlite is sometimes added to aerate the substrate. The substrates are inert and serve only as support for the roots of the plants. They are chosen for their ability to retain water, their aeration, their stability, and their cost. Since the substrates are inert, it is necessary to irrigate the plants with a mixture of water and nutrient solution, in order to provide the water and nutrients necessary for plant growth. Therefore, soilless cultivation is very practical when field cultivation is not possible, but also when one wants to improve precision by controlling all parameters of plant growth and for certified plants production (pathogens-free). Soilless farming allows for a higher level of precision than field farming since each plant can be tracked regarding its water and nutrient consumption, and its drainage discharges (the water released by the plants). Nutrient solutions are simple to adjust to meet specific plant needs. In addition, water used in soilless culture is generally better used by the plants than water applied in the field where losses are high due to evaporation and leaching. Therefore, a small percentage of the water used in the field can be used, and even the drainage water can be re-circulated by adjusting the nutrient ratios of the new solution. Substrates can also be washed and sterilized before reuse to avoid pathogen transmission and to remove a portion of the accumulated salinity.
A seed producer should establish a screenhouse for the hydroponic system. A screenhouse is a structure made with screens and a shade canopy to provide shade and keep insects out. The following are the desired characteristics of screenhouses for hydroponic seed production.
A screenhouse should be insect-proof.
It should have a high roof to ensure good airflow.
A shade net with 90% density should be used on the top of a high-roof screehouse. This means that it will block 90% of light.
It should have a fogging system to manage humidity during the dry and hot seasons.
Coconut Fiber as Substrate for the Hydroponic System
Benefits of using a coconut fiber substrate
Promotes good development of root system.
Allows roots to absorb nutrients more easily.
Promotes accelerated rates of vine growth.
Improves tuber formation.
Improves rooting of vine cuttings.
Can be reused for three cycles after disinfection.
In our trials, we used the type of bed with net and wood palettes filled with coco fiber.
Use a good amount of substrate (bed depth of 35cm).
Avoid damaging large tubers on contact with the net.
Allow more space for roots and tuber growth.
Vines can also be grown in pots as shown below. However, in trials, it was observed that the size of the small pots did not allow for good plant root development.
Next SEction: Seed Yam Production in Hydroponics
The next section provides detail on seed yam production in hydroponics.
A production calendar is provided to help you with the timing of planting and harvesting of seed yam over four generations.