Garlic (Allium Sativum)
The following are the crop details for garlic
Garlic is one of the most used crops among the cultivated Allium species. It is a perennial flowering plant that grows from a bulb that contains outer layers of thin, whitish sheaths or skin that enclose various lobes known as cloves. One garlic bulb may contain 10 to 20 edible cloves that are asymmetrical in shape, except for the small ones, which are close to the center. Cloves, which are also covered by protective whitish skin, have a distinctive smell.
Garlic, either in fresh or powdered form, is mainly used as a seasoning or condiment for flavoring food. It also has nutritional value, as raw garlic contains protein, starch, small amounts of fat and sugar, and high levels of potassium and vitamin C. Furthermore, garlic is widely valued for its medicinal importance as it contains bioactive constituents that are believed to help the body fight viral, fungal, and bacterial infections, among other health benefits such as lowering blood sugar and cholesterol levels, among others.
In addition, garlic extracts have pesticide properties that play a vital role in protecting plants from some pests and diseases like African armyworm, downy mildew, and rice bugs, among others. While it is beneficial in organic farming, its use as a pesticide should be moderated as it can kill beneficial soil bacteria and insects due to its broad-spectrum effects.
Garlic is believed to have originated in Central Asia (China). It then spread to the Mediterranean region in ancient times and was already known in Egypt by 3000 BC. Today, garlic is cultivated across the globe at latitudes ranging from 5 to 50 in both the northern and southern hemispheres.
The table below is a summary of the nutrition value per 100g of an edible portion of garlic
It is difficult to identify the wild primogenitor of common garlic due to the presence of numerous cultivars (clones). This makes it difficult to classify the clones. Despite this, there are two well-known garlic varieties, namely, cv. group Ophioscorodon, also known as hard-necked garlic, and cv. group Common Garlic, commonly referred to as soft-necked garlic (CABI, 2019).
While the cv. group Common Garlic has a straight stalk, the cv. group Ophioscorodon, on the other hand, has a curvy scape. In addition, hard-necked garlic is best suited for the northern climate, while soft-necked garlic flourishes in southern climates. The two varieties do well in Kenya, although the soft-necked is more commonly planted.
Temperature, and length of day are important factors in bulbing and bolting. Garlic is grown in a temperature-limited range of 9–28 °C. It is required that the propagules be exposed to 10–15 °C for 2 months to allow proper bulbing. Moreover, lower temperatures ranging from -2 to 6 °C are necessary for vernalization. Day length (>12 hours), on the other hand, stimulates clove formation. Garlic growth is easily adapted to all latitudes due to its wide genetic variation in response to temperature and day length. For instance, it is grown in the highlands around the equator to increase its growth. Also, garlic growth is recommended during the prevailing long-day season and at high altitudes in the tropics. In areas that experience long seasons of sub-freezing temperatures, mulching is advised to protect the plants from the cold. Mulching also conserves moisture and control weed growth.
Garlic requires fertile, well-drained, non-crusting mineral soil, in organic matter to increase yields. It should also be planted in raised beds to allow good soil drainage, which is essential.
Garlic plants perform well in areas with low rainfall since excess rain and humidity are bad for their growth. Regular irrigation during dry seasons is advised, where moisture in the top 30 cm of the soil should be maintained during the entire growth period to attain maximum yields. However, in some areas, stopping irrigation three weeks before harvest is recommended to prevent rotting and skin color loss.
i) Cultivation and planting
Prepare the soil a few weeks before planting for aeration; remove rocks and loosen the soil. While garlic can grow in soil with high organic matter, it can also grow in a variety of soil conditions and pH levels. A basal dressing of 200 kg/ha of triple superphosphate is recommended during soil tillage.
Garlic is usually grown as an annual crop. It is normally cultivated using cloves as seeds. To have quality and maximum yields, a farmer needs to plant healthy cloves. During seed selection, it is recommended that cloves planted should be of about equal weight (depending on cultivar) for uniformity purposes. The quantity of planting material is dependent on the size of the clove and the density of the plants.
During planting, place selected cloves 8–10 cm apart within the rows and 15-20 cm between rows to leave enough space for bulbs to grow and mature well. The cloves should be planted with the pointed side up and the base down. Garlic plants are best grown as sole crops on raised beds alternated with furrows. Protect the garlic cloves through mulching.
ii) Field operations
Planting, watering, weeding, and harvesting are all done by hand.
Avoid under-watering or over-watering the plants to allow optimal bulb formation. In cases where there is no rain, light watering (one inch deep) is enough. Dripline irrigation is recommended during the dry season.
Remove weeds that might hinder the crops from accessing maximum light, water, and nutrients. This can be done by mulching, hand hoeing, or spraying herbicides.
80 kg/ha of ammonium sulphate is mixed with 50 kg/ha of potassium chloride and 80 kg/ha of urea and then applied as side dressings at 15, 30, and 45 days after planting.
iii) Harvesting and storage
Garlic grows about 60 cm (2 feet) tall. The duration of subsequent growth and development phases strongly depends on the prevailing conditions. The total growing period varies depending on the area, where harvesting takes place 3–4 months after planting (in the tropics) to about 9 months (for winter garlic in temperate regions). Harvesting is done once the leaves start turning yellow and begin to dry up. Once ready, the farmer pulls the bulbs out of the soil using their hands. They are then tied in bunches for drying and later stored in a dry place with good ventilation to inhibit growth or decay.
Cabi Digital Library. (2019). Allium sativum (garlic). Retrieved on 2023-01-09 https://www.cabidigitallibrary.org/doi/abs/10.1079/cabicompendium.4250.
FatSecret. (Feb 4, 2008). Food database and calorie counter: Garlic. FatSecret Website. Retrieved Jan 11, 2023, https://www.fatsecret.com/calories-nutrition/usda/garlic?portionid=59114&portionamount=100.000
Infonet Biovision: Plant Extract: Garlic. Infonet Biovision Website. Retrieved Jan 11, 2023 https://infonet-biovision.org/PlantHealth/Plant-extract-Garlic
Mishra, R. K., Jaiswal, R. K., Kumar, D., Saabale, P. R., & Singh, A. (2014). Management of major diseases and insect pests of onion and garlic: A comprehensive review. Journal of Plant Breeding and Crop Science, 6(11), 160-170.
Welbaum, G. E. (2015). Family Amaryllidaceae, subfamily Allioideae. Vegetable production and practices, 267-288.