How can the germination rate of carrots be improved? Which factors affect seed germination?

Carrot seeds are thin and small, absorb water and germinate slowly, and have a low germination rate. This is especially true for autumn carrots, whose sowing period coincides with the high-temperature and rainy summer season, when the soil is easily compacted by rain erosion, making germination difficult. How can the germination rate of carrots be improved? Which factors affect seed germination?

1. Choose suitable soil

For the preceding crop of carrots, avoid cruciferous crops as much as possible to prevent black rot, black spot and soft rot, and it is best to rotate with allium vegetables. Although carrots have strong drought tolerance, their seed coat has a waxy layer that is not easily permeable to water and air, so if the soil lacks moisture, they often still do not emerge 20-30 days after sowing. Therefore, Gengzhongbang recommends choosing for carrot cultivation a sandy loam or loam with high, level terrain, deep soil layers, loose texture, strong water-holding capacity, good drainage, rich organic matter, and a soil pH of 5.3-7.0. At the same time, deep plow and loosen the soil, remove rubble and tree roots, make sure organic fertilizer is fully decomposed, and avoid clods. The soil surface should be fine and level. Otherwise, if the soil is level and the seeds are small with weak radicle penetration, emergence is often uneven.

2. Do the preparatory work for sowing

Because carrots have umbel inflorescences, the flowers that open later on the inflorescence and the seeds they form often have no embryo or a poorly developed embryo, resulting in a relatively low germination rate for carrot seeds, generally about 70%, and under poorer open-field conditions it can even drop to 20%. Therefore, try to use new seeds from the previous year, and when necessary conduct a germination test to determine the sowing rate; generally the sowing rate is 1.0-1.5 kg per mu. The surface of carrot seeds is densely covered with prickles, which easily stick together into clumps and affect contact between the seeds and soil, so before sowing, rub off the prickles on the seeds, then choose clear, windless weather and sun the seeds for 1-2 days. When necessary, soak the seeds to promote germination: soak them in warm water at 40-50°C for 2 hours, then keep them at 20-25°C to promote germination. Sow after most seeds have their radicles exposed. Because carrot seedlings grow extremely slowly and have very weak absorption capacity, 8-10 kg of quick-acting nitrogen fertilizer can be added per mu in the base fertilizer. In addition, carrot seedlings are extremely sensitive to the salt concentration in the soil; excessively high salinity affects seedling growth.

3. Pay attention to improving sowing quality

First, pay attention to sowing early at the right time. Carrot seeds are small, emergence is slow, seedlings grow slowly, and the growing period is long; medium- and late-maturing varieties all have a growing period of more than 100 days, so they should be sown early at the right time, especially for autumn sowing, so as to make full use of the growing season and promote early maturity and high yield. Generally, autumn carrots should be sown 10-15 days earlier than vegetables such as radish and Chinese cabbage, and in Northeast China no later than the end of June.

Second, adopt a suitable sowing method to promote early emergence, full emergence and uniform emergence. When sowing, a small amount of green vegetable seeds can be mixed in and sown together, using the fast emergence of green vegetables to provide shade. This helps carrot seedlings emerge. In terms of sowing method, small raised ridges with drilling are suitable, sowing 2 rows per ridge, with a furrow depth of 2-3 cm.

Third, after sowing, the covering soil should not be too thick, and the soil should be pressed down, which helps seedlings emerge.

4. Strengthen management after sowing

Treat the soil surface in time. After sowing carrots, to prevent rain from loosening the soil, a layer of short wheat straw cut into 2-3 cun lengths can be spread on top to help seedlings emerge. If sowing is too shallow or rain causes compaction that makes emergence difficult, promptly use a tool to break the soil surface to promote emergence, but be careful not to expose the seeds on the ground. Pay attention to keeping the soil surface moist. Carrot seeds germinate very slowly, so from sowing to emergence, water 2 or 3 times continuously, or water thoroughly before sowing. Generally, maintaining soil moisture at 65%-80% is suitable; too wet or too dry is not conducive to seed germination. The period from when carrot cotyledons emerge above the ground until true leaves appear is also a key period for management. In particular, autumn-sown carrots are very prone to seedling burn caused by dry, hot soil, causing the tender stems of the seedlings to become pinched and die, so special attention should be paid to keeping the soil moist to preserve the full stand. In addition, carrot seedlings are not tolerant of waterlogging, so summer-sown carrots also need timely drainage during the rainy season. Also promptly remove weeds and control diseases and insect pests.