**4.3 Types of nurseries**

There are three types of nurseries in vegetable cultivation. These are the nursery bed (seed bed), seed box (containers) and the plug trays (V-type nursery) [35]. The nursery bed is the commonest method of raising seedlings at the nursery [32]. In this method, seeds of vegetable crops are nursed on either raised or sunken beds depending on the season. Raised beds are used during the rainy season to prevent waterlogging whiles sunken beds are preferred in the dry season to conserve moisture. Vegetable nurseries can also be set up in seed boxes or containers. The advantage of using seed boxes is that they can be moved to a safer place in the event of unfavorable weather conditions. The last type of nursery is the use of plug trays. The plug trays are specially designed plastic trays for raising seedlings of vegetable crops [34, 35]. With the plug tray, each seedling occupies a cell (hole) which reduces competition and ensures uniformity among the batch seedlings. They can also be used for commercial production of seedlings of vegetable crops that are not normally nursed for example the Cucurbits. This is possible because the rooting system of the seedling is not disturbed during transplanting. Plug trays come in different sizes with the different number of cells (holes). The type of tray to use depends on the vegetable crop. Vegetable crops with small-sized seedlings should be raised in trays with smaller cells while large seedlings should be raised in trays with larger cells [34].

*Harnessing Technologies for Vegetable Cultivation: A Panacea for Food and Nutrition Insecurity… DOI: http://dx.doi.org/10.5772/intechopen.101877*

### **4.4 Sterilization of growth media**

To produce healthy vegetable seedlings, the growth media (soil or soilless media) should be sterilized to kill or reduce the population disease-causing pathogens. The growth media can be sterilized using heat from fire (conventional method), heat from steam, solar radiation, and chemicals (fumigants). In seed bed nurseries, the commonest method of sterilizing the soil is through heat sterilization by burning dry grass on the beds. The solarization method is mostly practiced in greenhouse nurseries. However, it can be used to sterilize the main field. In the method, the nursery bed is moistened and covered with transparent plastic sheets which allows sunlight to pass through and heat up the moistened soil. The steam sterilization method is mostly used in sterilizing growth media for seed boxes and plug tray nurseries. Chemical sterilizers (fumigants) are also used in sterilizing the nursery bed but their use is limited due to the non-availability and high cost of the fumigants.

#### **4.5 Types of growth media**

Seeds of vegetable crops can be nursed in soil or soilless media such as cocopeat (coconut husk), decarbonized rice husk, saw dust, vermiculite, perlite, peat soil [32]. Most of these soilless media do not contain plant nutrients and therefore should be mixed with well-decomposed manure or compost to supply nutrients to the seedlings.

#### **4.6 Good nursery management practices**

Irrigation or moisture management: This is very crucial at the nursery since inadequate moisture supply may cause the death of seedlings while the excess of it will create conducive conditions for the spread of diseases. Insect pest and diseases management: The use of recommended insecticides and fungicides have been the commonest method of controlling insect pests and pathogen at the nursery. Recently, the use of colored sticky pads have proven to be effective in controlling flying insects such as whiteflies and aphids at the nursery.

Weed management: Weeds are good competitors for productive resources such as water, sunlight, and nutrients, and for this reason they must be controlled at the nursery. In the case of seed beds, manual hand weeding can be done to control weeds. Pre-emergence herbicides can be used to control weeds before sowing seeds. However, care must be taken to avoid the residual effect of the herbicides on the vegetable seeds. In the case of seed boxes and plug trays, effective sterilization will kill most of the weed seeds. Hand-picking can be done to get rid of weed seeds. Pricking out: Overcrowded seedlings in seed beds and seed boxes should be pricked out to reduce competition for productive resources. Pricking out is not required in plug trays since each seedling occupies a cell. Hardening off: It is one of the most important agronomic practices at the nursery. It refers to a gradual process of exposing seedlings to conditions in the field where they will be transplanted. It involves a gradual withdrawal of water and exposure of the seedlings to sunlight with the aim of reducing transplanting shock and increasing percentage seedling survival.

#### **5. Protected/screenhouse vegetable cultivation**

This refers to growing vegetable crops in protected structures such as polyhouses, greenhouses, net houses, shade houses, net tunnels [32]. Protected vegetable cultivation technology became necessary due to the challenges associated with vegetable cultivation in the open field [36]. The protective structures serve as a mechanical barrier to biotic stresses such as insect pests and disease-causing organisms and rodents [37]. The structures also protect the vegetables from harsh environmental conditions such as rainstorms, scorching sunlight, sandstorm, high winds, etc. These protected structures differ in the level of control or automation of the growing conditions such as temperature and relative humidity. The commonest protective structures in Ghana are net houses mostly without temperature controlling devices. The increasing demand for the use of protective structures for vegetable cultivation is the high yield and improved quality of the product obtained under protected cultivation compared to open field cultivation [37, 38]. Additionally, certain vegetable crops are vulnerable to high rainfall or windy conditions and therefore only perform better when grown under protected structures. Growing vegetables in protected structures can extend the growing season and ensure allyear-round production and supply of vegetables since climatic and growing conditions can be optimized in the protected structures [36]. Protected structures such as greenhouses can double as a commercial nursery where high-quality disease-free seedlings of vegetable crops could be produced and supplied to farmers to boost vegetable production. The production of true-to-type (genetically pure) seeds of cross-pollinated vegetable crops is challenging during the main cropping season. However, vegetable seed production in protected structures helps maintain genetic purity without worrying about isolation distances.
