How to grow radishes in summer? Key cultivation techniques

Radish, a root vegetable, also known as laifu or water radish, with a fleshy root that is oblong, spherical or conical. It originated in our country and has a great many varieties, including green-skinned, red-skinned and white-skinned types. It has a variety of culinary and medicinal values.

Growth and development of radish

The growth and development process of radish can be divided into: the vegetative growth stage, the seedling stage and the fleshy root growth stage of planted radish.

Temperature requirements of radish

The most suitable temperature for radish seed germination is 20-25°C, and germination begins at 2-3°C. The seedling stage can tolerate the higher temperature of 25°C and can also endure short periods of low temperature of -2 to -3°C. The suitable temperature for leaf growth is 18-22°C, and the most suitable temperature for fleshy root growth is 15-18°C. Above 25°C the plant grows weakly and product quality is poor, so the suitable temperature for radish growth is high in the early stage and low in the later stage. Alpine radish cultivation is often low in the early stage and high in the later stage. If plastic film mulching cultivation is used, it is not affected by temperature. At present, cold-tolerant varieties from South Korea are selected; they have a wide range of adaptation, and as long as the early-stage temperature is slightly low but not below 10°C, growth and quality are also unaffected. In summer and autumn, high daytime temperatures and low nighttime temperatures also favor nutrient accumulation and the swelling of the fleshy root.

Radish cultivation still has certain temperature requirements, so summer radish must focus on management. So how should radish be cultivated well in summer?

Use good varieties: selecting the right superior varieties is a prerequisite for obtaining high quality and high yield in over-summer radish. Therefore, when cultivating radish in the hot summer season, early-maturing varieties with good heat tolerance and strong stress resistance must be selected.

Apply sufficient base fertilizer:

Early-maturing radish has a short growth period and relatively high nutrient requirements, so sufficient base fertilizer must be applied in combination with land preparation. The amount of base fertilizer applied should account for 70% of the total fertilizer application; per mu, 4000 kg of fully decomposed farmyard manure and 30-40 kg of compound fertilizer can be applied. Radish should be cultivated in deep furrows and high beds, with a bed height of 25-30 cm.

Sowing and raising seedlings:

When cultivating radish in over-summer and early autumn, sowing can be done in batches from May to August according to market demand during the summer-autumn off-season. There are two sowing methods, dibbling and broadcasting, which can be reasonably chosen according to the variety type. Large-fruit varieties should be dibbled, with a plant spacing of 20 cm and a row spacing of 35 cm; the sowing holes should be shallow, and after sowing the seeds should be covered with fine soil; small-fruit varieties can be broadcast, and after thinning the plant spacing should be maintained at 6-12 cm. After sowing, cover the bed surface with rice straw or shade netting to protect against sun and reduce heat, prevent heavy rain from washing it away, and reduce the loss of fertilizer and water. After full emergence, remove the rice straw and shade netting in time to avoid pressing the seedlings or causing them to become thin and weak. During the seedling stage, thinning must be done early and final thinning late. After the seedlings emerge, they grow rapidly; when the seedlings have 1-2 leaves and 3-4 leaves, thin them once each time, and when the seedlings reach the 5-6 leaf stage, final thinning is done.

Fertilizer and water management:

Radish has a relatively high water requirement, and the amount of water is closely related to yield and quality. Too much water makes the radish skin rough and also easily causes cracked roots and rot; lack of water during the seedling stage easily causes viral disease. When fertilizer and water are insufficient, the fleshy root of radish is small and lignified, with a strong bitter and pungent taste, and is prone to pithiness. In cultivation, water should be supplied evenly according to the characteristics of each growth stage of radish and its water needs; do not let it alternate between dry and wet. After sowing, water thoroughly, and after most seeds have emerged, water once more to help achieve full stands. After planting, the seedlings quickly enter the peak leaf growth stage, so water appropriately. In the late vegetative growth stage, water should be properly controlled to prevent excessive leaf growth from affecting fleshy root growth. When the plant has 12-13 leaves, the fleshy root enters the rapid growth stage; at this time fertilizer and water supply should be sufficient, and watering should be done flexibly according to weather and soil conditions.

After heavy rain, drainage must be carried out in time to prevent excess water from waterlogging the roots and causing cracked or rotten roots. In hot and dry seasons, insist on watering in the evening, and never water at noon, to prevent tender leaves from wilting and fleshy roots from rotting; stop watering 7 days before harvest. Radish also has special nutrient requirements; boron deficiency can cause the fleshy root to turn black and become pithy. During the fleshy root enlargement stage, appropriately increase potassium fertilizer. From emergence to final thinning, apply seedling-protecting fertilizer as appropriate; when the seedlings have 2 true leaves, apply a small amount of fertilizer; after the second thinning, apply fertilizer once in combination with intertillage and weeding. During the period from "breaking white" to "showing shoulders" in radish, carry out the second topdressing, and afterward apply topdressing according to seedling growth. It should be noted that topdressing should not be placed close to the fleshy root, so as to avoid burning the roots. Intertillage and weeding can be carried out in combination with irrigation and fertilization; intertillage should be deep first and then shallow, near first and then far, and stop intertillage after the rows close.