Lettuce

The scientific name of lettuce is Lactuca sativa. It is a one-year plant from the family of sunflowers.

Weather requirements:
Lettuce is a cool season plant. Planting this plant in moderately cold and moderately humid areas gives the best results of harvesting. However, if the seed is planted in the seasons when plant growth is not affected by extreme heat, it also gives a relatively good yield.

Also, this plant is semi-resistant to cold, that’s why it is cultivated mostly in spring and autumn. Plenty of light, cool nights and soil moisture are needed to produce good and plump lettuce.

Late and heat-resistant lettuce can be planted until the end of April and its product can be used until the end of June and the beginning of July. In this order, fresh lettuce can be planted in all seasons of the year. Lettuce grows well in all regions where the average monthly temperature is 12 to 15 degrees Celsius.

Lettuce is very sensitive to high heat. When the heat is high, its leaves start to burn. At a temperature of 30 degrees Celsius, the seed falls asleep and does not germinate. Lettuce farm needs a lot of irrigation.

Therefore, the lettuce field should never be completely dry. The temperature of the rearing environment should be between 16 and 18 degrees Celsius during the day and between 10 and 12 degrees Celsius at night.

Lettuce is one of the vegetables that can be cultivated all year round provided the weather is suitable. If the weather warms up at the same time as the lettuce is harvested, it will not grow enough and the flowering branch will appear and the lettuce plant will produce seeds.

At this time, the leaves get a bitter and unpleasant taste and become unusable. The best areas for growing lettuce are cold areas with high humidity. In winter crops, due to successive rains, curly lettuce is produced, whose leaves are extremely soft and thin. Lettuce plant is different in terms of sensitivity to light and semi-sensitive to salinity.

Selection of varieties and seeds
1- Lettuces that have elongated heads and the most amount of cultivation in the country is related to this type.

2- Spinach lettuce or cabbage

3- Leafy lettuces

Of course, this type is good for home cultivation, but it does not have much economic value from a commercial point of view.

4- Using cultivars that are resistant to long days and hot weather and do not go to seed early.

Properties of lettuce
Lettuce is rich in vitamins and essential substances for human health. The presence of large amounts of iron, manganese, phosphorus, potassium, beta-carotene, vitamins C and B in lettuce leaves has improved the nutritional value of this vegetable. This plant is a rich source of antioxidants among vegetables. Also, lettuce is a plant that has cellulose, sleep-inducing and appetizing substances, blood purifier and contains elements of zinc and manganese. China is the largest lettuce producing country in the world with a share equal to 64% of global production. After that, the countries of America, Spain, Italy, India, Japan, France, Turkey, Mexico and Germany are in the next ranks respectively.

After sowing the seeds, lettuce produces a vertical and deep root, and then secondary roots are formed on this main root, whose task is to absorb water and nutrients. Environmental conditions, planting date and planting intervals have an effect on the size and number of leaves. Lettuce leaves are usually smooth and hairless, and the sides have small cuts. Of course, some cultivars may have wrinkled and hairy leaves.

The leaf blade can be elongated oval, wide oval, round, egg-shaped, spoon-shaped, and triangular. The growth habit of the leaves varies from lying down to standing up. The presence of anthocyanin in the leaves causes them to turn red.

Advantages of lettuce cultivation
1- Reduce irrigation frequency

2- Early delivery of the product

3- Uniformity of killing

4- Proper density of the plant

5- Reducing the cost of seeds

Soil preparation
1- Lettuce can be grown in a wide range of types of soil, but the most cultivated area is related to organic and loamy soils. It should be noted that regardless of the final quality of lettuce, the best type of soil for growing lettuce is light and sandy soil.

2-First do a proper plowing.

3- The crispness of lettuce is one of the most important issues that plays a special role in the market of lettuce, and for this, the growth stages of the lettuce plant must be fast. For this purpose, food should always be provided to the plant in a principled way.

4- Due to its surface roots, lettuce absorbs nutrients less than other vegetables. For this reason, the roots of this plant cannot look for food in the soil like other plants.

Therefore, the desired soil should be fertile enough to harvest a valuable and quality product in the end, and in the meantime, the nitrogen element plays a vital role in the rapid growth and expansion of the lettuce body. For this purpose, 33 kg should be given to lettuce before each planting and the same amount after thinning. Any other type of additional nitrogen is related to the amount of nitrogen in the soil itself, as well as the extent of its leaching in the soil, which also depends on the soil texture.

6- Add phosphorus and potash fertilizers to the soil before planting depending on the needs of the land (soil).

7- To get better results, it is recommended to use nitrate and ammonium fertilizers together rather than using only one type. Phosphorus is also one of the vital elements for making the product early.

Suitable soil for lettuce
Lettuce is grown in a variety of light sandy soils to heavy clay, but planting this plant in loamy soils with organic matter gives the best results. Spring lettuces in light fields that heat up quickly They grow better. The summer varieties of this plant produce good results in lands with sufficient water. The most suitable soil for lettuce is light lemon soil that has a lot of organic matter. Semi-heavy soils with humus materials that have good permeability and high water holding capacity are suitable for lettuce. The suitable pH for lettuce is between 5.5 and 6.5. Lettuce does not produce well in neutral soils due to lack of absorption of iron and manganese. The land where lettuce is grown must have good drainage and at the same time maintain moisture, and the surface of the soil must be smooth and soft and free of weeds.

According to the explanations given, chemical fertilizers containing the three main elements of nitrogen, phosphorus and potassium, as well as fertilizers containing zinc, can be effective in improving the performance of lettuce plants. Cinco offers liquid and powder NPK fertilizers, urea phosphate, as well as zinc sulfate fertilizer and organic fertilizers, including zinc acetate.

source

Nutritional management in the production of commercial varieties of lettuce – Abdulhamid Mohebi and Seyed Hassan Mousavi – 2019