Key Techniques for Overwintering Spinach Seedling Protection and Field Management
Spinach (Spinacia oleracea L.), also known as Persian spinach, red-root spinach, parrot spinach, etc., belongs to the genus Spinacia in the subfamily Chenopodioideae of the family Amaranthaceae, and is an annual herbaceous plant. The plant can reach 1 m in height, with a conical root that is reddish, less often white, and leaves that are hastate to ovate, bright green, with entire or occasionally few tooth-like lobes. There are many varieties of spinach, which can be divided by seed morphology into two variants: the prickly-seeded type and the smooth-seeded type. Spinach originated in Iran and is widely cultivated in China, making it one of the most common vegetables.
Nutritional composition of spinach: Plain spinach contains vitamin A, vitamin B, vitamin C, vitamin D, carotene, protein, iron, phosphorus, oxalic acid, etc. Although spinach is a vegetable relatively rich in iron, the difference from other vegetables is not great. The misunderstanding that spinach has an extremely high iron content originated from a book published by E. von Wolf in 1870, in which a decimal point in spinach's iron content was printed as a comma, thus multiplying the figure tenfold, and this gave rise to the comic Popeye the Sailor. It contains a large amount of plant crude fiber, which can promote intestinal peristalsis and facilitate defecation.
Spinach is the whole plant with roots of the Amaranthaceae plant spinach. Spinach is also called bo suo, red-root spinach, Persian grass, Persian spinach. Spinach has the effects of moistening and lubricating the intestines and clearing heat and relieving restlessness. Spinach is rich in nutritional value. Spinach leaves contain zinc 56-68 mg/kg (dry weight), folic acid 1.22 micrograms/g, amino acids and lutein, β-carotene, neo-β-carotene B, neo-β-carotene. Spinach also contains carotenoids such as spinacin U, as well as α-spinasterol, cholesterol, and sterol esters and sterol glycosides, tagetin, spinaciaxanthin, and a blue-purple fluorescent substance, 2-acetyl-3-p-hydroxycinnamoyl-meso-tartaric acid.
Spinach contains nutrients such as water, carbohydrates, protein, fat, dietary fiber, carotene, vitamin B1, vitamin B2, vitamin C, potassium, sodium, calcium, phosphorus, xian, magnesium, etc.
Spinach has a certain therapeutic effect on constipation and hemorrhoids. In addition, spinach can also promote human health, prevent aging, prevent and treat iron-deficiency anemia, and promote the respiratory system; spinach is rich in vitamin C and folic acid, which can enhance postpartum women's absorption of iron and is an ideal food for iron-deficiency anemia. The dietary fiber in spinach can play a very good laxative role.
How to protect spinach seedlings and manage the field in winter?
Spinach seedling protection measures
1. Water the freezing water well. Watering the freezing water must achieve "one determination" and "two suitability." "One determination" means deciding whether to water the freezing water according to the soil moisture content. Generally, when the absolute moisture content of sandy loam is below 15%, loam below 17%, and clay below 20%, freezing water should be applied. "Two suitability" means watering at the right time and in the right amount. The suitable time for watering the freezing water is when the soil plow layer can thaw during the day and freezes at night. Proper amount of watering means the amount of freezing water should not be too large or too small. Generally, it is suitable when it connects with the subsoil moisture.
2. Apply overwintering fertilizer well. Applying overwintering fertilizer can increase soil nutrient content, serve the purpose of using winter fertilizer in spring, and promote weak seedlings to become strong. This is especially important for vegetable plots with little base fertilizer, poor soil fertility, and weak seedlings. Therefore, overwintering fertilizer should be applied together with watering the freezing water, generally 10 kg of urea or 20 kg of ammonium sulfate per mu, applied with the water.
3. Mulch for cold protection. In the severe cold period in northern regions, extremely low temperatures are very unfavorable for the safe overwintering of vegetable seedlings, so mulch should be used for cold protection to ensure the safe overwintering of seedlings. Mulching can generally be carried out after the entire plow-layer soil has frozen. The mulch is farmyard manure rich in organic matter and crushed and finely broken, scattered at about 1000 kg per mu.
Field management measures for overwintering spinach:
1. Overwintering period management. From when spinach stops growing to before it turns green again the following spring is the overwintering period. To prevent cold and drought damage, a freezing water can be applied before freezing; if fertilization is insufficient, urine water can be mixed in. After freezing, horse manure or pen manure can be spread to protect seedlings through winter. Before turning green, choose clear and warm weather, and after the frost has melted, splash fresh urine, 1000-2000 kg per mu, finishing at 3-4 p.m.
2. Management during the vigorous growing period after turning green. In early March of the following year, spinach begins to turn green and grow. Because the temperature is still low at this time, if the soil moisture is good, watering can be temporarily omitted and hoeing can be used to preserve moisture; if the soil moisture is poor and the temperature rises quickly, one watering can be given, and the amount should be small rather than large. However, saline-alkali land can be appropriately watered to press down salt. In windbreak beds and sandy loam, the temperature rises quickly, so watering should be appropriately earlier. After spinach begins vigorous growth, the demand for fertilizer and water increases sharply. During this period, the soil should be kept moist and not allowed to dry out, and topdressing and watering should be done promptly to promote vegetative growth and delay the bolting period. Generally, 15-20 kg of urea is applied per mu. Watering after fertilization, with sufficient fertilizer and water, makes spinach grow quickly, and it can be harvested in 10-15 days. Adopting windbreak and flat mulching cultivation methods in early spring (mulching for 7-10 days) can achieve the goals of earlier marketing and high yield.
3. Pest and disease control. The main pests and diseases of overwintering spinach include downy mildew, anthracnose, viral disease, and aphids. For downy mildew and anthracnose, in the early stage of disease, spray with 75% chlorothalonil 600 times solution, 25% metalaxyl 700-800 times solution, or 40% fosetyl-aluminum wettable powder 200-300 times solution. For viral disease, in addition to crop rotation, aphids and other virus-transmitting vectors should also be controlled in time. Aphids can be controlled with pesticides such as imidacloprid.