Key points for growing vegetables on the balcony that need to be known about the growth and development of vegetables
The editor introduces you to the experience of melons, fruits and vegetables. It is necessary to know the key points of the growth and development of vegetables when growing vegetables on the balcony. The following is a detailed introduction.
I. Classification of vegetable temperature requirements
According to the different temperature requirements of various vegetables and the temperature they can tolerate, vegetable plants can be divided into five categories.
1. Cold-tolerant perennial root vegetables: including scallions, daylilies, asparagus, etc. During the growing season, the aboveground parts can tolerate high temperatures, the aboveground parts die in winter, and the underground root (stem) overwinter, which can tolerate -10℃ of low temperature.
2. Cold-tolerant vegetables: including spinach, coriander, scallions, onions, garlic, etc., which grow best at 15-20℃, and can tolerate -1 to -2℃ of low temperature.
3. Semi-cold-tolerant vegetables: including Chinese cabbages, small cabbages, radishes, carrots, cabbage, peas, broad beans, etc., which grow best at 17-20℃, and can tolerate short-term low temperatures of -1 to -3℃.
4. Warm-loving vegetables: including cucumbers, tomatoes, peppers, green beans, eggplants, etc., with an optimal growth temperature of 20-30℃, intolerant to frost, easily causing flower drop below 15℃, and poor growth and fruiting above 35℃.
5. Heat-tolerant vegetables: including wax gourds, pumpkins, watermelons, cowpeas, sword beans, amaranth, water spinach, etc., which grow better at about 30℃, and can still grow and bear fruit at 35-40℃.
Warm-loving and heat-tolerant vegetables must be cultivated in protected facilities such as greenhouses in winter. Cold-tolerant or semi-cold-tolerant vegetables require early summer or early autumn cultivation, and shading and mulching measures or mountain off-season cultivation should be adopted.
II. Temperature cycle and vegetable production
The response of vegetable crops to the diurnal temperature cycle is called the vegetable temperature cycle. Vegetable crops require higher temperatures during the day for photosynthesis, while lower night temperatures can reduce the consumption of storage materials and are conducive to the transport and storage of assimilates.
There is a certain range for day-night temperature differences, and night temperatures cannot be too low because vegetable crops still absorb water and nutrients at night. Therefore, it is necessary to pay attention to the day-night temperature management of protected cultivation. On sunny days with sufficient light, the day-night temperature difference should be larger, while on cloudy days, the day-night temperature difference should be smaller.
The temperature cycle is of great significance for guiding vegetable cultivation. For example, when determining the sowing season, the formation time of the product organ is arranged in periods with large day-night temperature differences to facilitate nutrient accumulation and promote the expansion of the product organ. Also, when seedlings are raised, different day and night temperature management measures are taken at different stages to promote and control seedling growth and cultivate strong seedlings. In protected cultivation, the day and night temperatures are often divided into several segments for regulation according to the weather conditions, such as the day temperature being 2-5℃ higher on sunny days than on cloudy days, the night temperature being 1-4℃ higher on sunny days than on cloudy days, the temperature in the afternoon being 2-5℃ lower than in the morning, the temperature being higher 3-4 hours after sunset to facilitate nutrient transport, and then the temperature continues to decrease to maintain the minimum nutrient consumption.
III. The impact of soil temperature on vegetable growth
Within a certain range, an increase in soil temperature can accelerate growth. Different types of vegetable roots have different optimal temperatures for absorption. Warm-loving vegetable roots require higher soil temperatures for growth, and the suitable temperature for root elongation and penetration into the soil is 18-20℃, with cucumber and sweet pepper roots being very sensitive to low temperatures.
In vegetable production, watering should be controlled in winter and spring to prevent the reduction of soil temperature, which affects root growth and absorption. Measures such as tillage and mulching or covering the ground with plastic film can be used to increase soil temperature and retain moisture. In winter and spring, soilless cultivation of warm-loving vegetables often suffers from poor growth due to low water temperatures, so it is important to increase the temperature of the nutrient solution. Too high soil temperatures also affect growth, with root absorption ability weakening when soil temperatures exceed 25℃, and root growth inhibited and plants easily diseased when soil temperatures are above 30-35℃. In summer, measures such as frequent light watering, earthing up, and mulching can be used to lower soil temperatures and protect the roots. Additionally, it is not advisable to suddenly water in the middle of a hot summer day, causing a sudden drop in root zone temperature, which can lead to plant wilt or even death.
IV. The harm of high temperature and low temperature to vegetable growth and development
(一) Harm caused by high temperature
1. High temperature accompanied by strong light can cause plant dehydration and wilt, and if water is not kept up, it can lead to plant death.
2. High temperature affects pollen viability, leading to flower drop and reduced fruit setting rate in solanaceous and leguminous vegetables, with an increase in malformed fruits.
3. High temperature and strong light can easily cause scorching of tomato, watermelon, wax gourd, and pepper fruits.
4. High temperature and strong light can lead to a decrease in photosynthesis and an increase in respiration, causing a deficiency in internal nutrients and poor growth.
5. Affecting flower bud differentiation and sex differentiation: High temperature and long-day conditions often lead to an increase in male flowers in cucumbers and late female flower differentiation. Fewer flowers and poor development occur in tomatoes and peppers under high temperature conditions.
6. Affecting the normal formation of pigments: When tomatoes are exposed to high temperatures (above 35℃), lycopene is difficult to form normally, resulting in fruits with a mixture of yellow, red, and white colors, greatly reducing their commercial value.
To cultivate vegetables resistant to high temperatures, it is first necessary to select heat-resistant varieties. Additionally, watering in the early morning and evening during high temperature periods, cultivating in water basins to lower temperatures, using shade nets, or covering the ground to reduce temperatures can be effective. In greenhouse cultivation in winter and spring, attention should be paid to ventilation and cooling on sunny days to prevent high temperature damage.
(二) Harm caused by low temperature
Low temperature harm can be divided into two situations: cold injury and frost injury. Cold injury refers to the damage to vegetables at temperatures above 0℃, while frost injury refers to the damage to vegetables at temperatures below 0℃ due to internal ice formation.
1. Solanaceous vegetables, melons, and leguminous vegetables often suffer from flower drop and reduced pollen viability at low temperatures, affecting fruit setting rate and resulting in malformed fruits.
2. Low temperatures often cause biennial vegetables (such as cabbages, kale, and root vegetables) to bolt before the product organ is formed or during formation.
3. Frost injury at temperatures below 0℃ often causes tissue damage, dehydration, and drying, leading to plant death.
4. Low temperatures hinder the normal growth of vegetables, affect root water absorption, leading to water imbalance and possible plant wilt, inhibit chlorophyll formation, causing leaves to turn yellow or yellow-white, which is a typical symptom of cold injury in warm-loving vegetables.
5. Early spring sowing of warm-loving vegetables often results in seed rot, with seedlings encountering low temperature and rainy conditions, leaves gradually turning yellow, roots turning rusty-brown, lateral roots and root hairs dying, and the aboveground parts wilting, commonly known as "rotten roots and fallen seedlings."
Cultivation can involve selecting cold-tolerant varieties, conducting low-temperature seedling training, applying phosphorus and potassium fertilizers to prevent excessive growth, and improving the quality of seedlings or plants to enhance cold resistance. Measures such as watering or foliar spraying can also be used to increase near-ground air humidity to reduce frost injury. The most effective method is to use plastic film mulching cultivation measures or smoking, ground heating, and other measures to prevent low temperature injury.
V. Low temperature vernalization and vegetable production
Biennial vegetables (such as Chinese cabbages, kale, celery, spinach, radishes, etc.) require certain low temperature conditions before bolting and flowering. This physiological process of requiring a period of low temperature to bolt and flower is called "vernalization" or "vernalization stage." After passing the vernalization stage, bolting and flowering occur under long-day conditions and higher temperatures. The conditions required for vernalization in biennial vegetables vary depending on the vegetable type and can be basically divided into two categories.
1. Seed vernalization type vegetables: such as Chinese cabbages, radishes, mustard greens, spinach, lettuce, etc., which can pass the vernalization stage at any time from seed germination as long as there is a period of suitable low temperature, and then bolt and flower after long-day conditions and higher temperatures. Most vegetable vernalization requires temperatures of 0-10℃, with 2-5℃ being optimal, and some vegetable types or varieties can vernalize stably at temperatures up to about 15℃ or higher, with a required continuous low temperature period of 10-30 days. This type of vegetable has a wide temperature range for vernalization and a shorter required time, making it easier to encounter such conditions in production. Therefore, improper variety selection or sowing time arrangement can easily cause bolting and flowering before or during the formation of the product organ, a phenomenon known as "early bolting" or "immature bolting." For example, spring Chinese cabbages should select varieties such as "Yangchun" and "Chundajiang," which have lower temperature requirements and longer duration for the vernalization stage, and are less likely to bolt early. Chinese cabbages are seed vernalization types and should be raised with ground heating to avoid low temperature effects during the seedling stage, which can cause bolting. Additionally, the sowing time should not be too early, and mulching cultivation should be used. For off-season cultivation of Chinese cabbages in the mountains, the selection of sowing time is very important, for example, "Xiayang" Chinese cabbages sown in the mountains (800-meter-high) mountains in early April can easily lead to bolting and flowering without forming heads.
2. Green body (seedling) vernalization type vegetables: such as kale, onions, celery, etc., which must grow to a certain size before they can be affected by low temperatures and pass the vernalization stage. Low temperatures have little effect on the germinated seeds and very young seedlings of these vegetables.
A certain size of plants is usually indicated by leaf number and stem thickness.
The above[] introduces the specific content of the key points for growing vegetables on the balcony that need to be known about the growth and development of vegetables. Unauthorized reproduction is prohibited!