How to rejuvenate 'Ai Datou' garlic? Master these key measures

Tongling County, Anhui Province, China is located in the middle and lower reaches of the Yangtze River. Garlic, as one of the "Eight Treasures of Tongling," has a long history of cultivation, especially the local variety 'Ai Datou', which has a unique flavor and is highly favored by people. Due to various reasons, 'Ai Datou' has shown serious variety degeneration: the per-unit yield of garlic scapes and garlic bulbs has dropped substantially, quality has deteriorated, and a large number of undesirable traits such as single-clove garlic, single-segment garlic and multi-segment garlic have appeared.

1 Causes of variety degeneration in 'Ai Datou'

1.1 Long-term asexual propagation

'Ai Datou' has always been propagated by planting garlic cloves in the Tongling area. Due to lax seed selection and improper methods, small cloves, diseased cloves and damaged cloves are often used as seed. Many factors cause the progeny to retain the superior traits of the parent while also retaining the degenerative traits of the parent. Long-term accumulation has led to severe variety degeneration in 'Ai Datou'.

1.2 Improper cultivation methods

Excessive planting density results in poor nutrition and poor maturation of individual plants kept for seed, leading to deterioration in the quality and traits of the seed garlic; because garlic scapes fetched high prices in the early period, vegetable growers harvested the scapes too early, causing excessive consumption of nutrients in the garlic bulbs; improper tools and methods frequently damaged the bulbs.

1.3 Improper cultivation management

Due to long-term continuous cropping, low application of organic fertilizers such as farmyard manure, and excessive application of chemical fertilizers, the physical and chemical properties of the soil were altered. During the seedling growth period, insufficient fertilizer and water or damage to the cotyledons made the plants grow weak and spindly, resulting in very little growth at the beginning of bulb formation and the appearance of single-clove garlic or small-clove garlic.

1.4 Influence of climatic conditions

Due to weather conditions, late spring cold spells often occur during the garlic bulb swelling period. With too many low-temperature days, garlic leaf growth is small, producing single-clove garlic, few-clove garlic or multi-segment garlic.

2 Measures for rejuvenating 'Ai Datou' varieties

2.1 Intensive and meticulous cultivation

It is best to choose sandy loam soil with deep soil layers and rich organic matter. Apply sufficient base fertilizer 1 week before planting: per 667 sq m, apply 20 kg urea, 20 kg potassium chloride, a small amount of potassium dihydrogen phosphate and 150 kg decomposed cake fertilizer or several loads of decomposed human manure and urine, spread evenly in the field, plow the land deeply, and rake the field level.

2.2 Tissue culture

Under the leadership of the Tongling Municipal Institute of Agricultural Sciences, asexual propagation of 'Ai Datou' has been successfully carried out. Using stem tips and root tip growing points as tissue culture materials, virus-free seedlings were cultivated under aseptic conditions, planted in the field, and retained for seed propagation.

2.3 Strict seed selection

Before harvest, select healthy, disease-free plants from which garlic scapes have already been harvested and keep them for seed. When the garlic leaves begin to turn yellow and wither, tread down the aboveground stem portion and let them after-ripen for 3-4 days. At harvest, select plants with round, regular garlic bulbs that are disease-free and undamaged, dry them together with the aboveground parts for 1-3 days, tie them into bundles, and store them in a pile or hang them in a cool place. At planting time, once again select garlic bulbs that are round and regular, large and undamaged, and free of pests and diseases, peel off the garlic skin, and remove curved and excessively small garlic cloves.

2.4 Propagation by aerial bulbs

Aerial bulbs are small in size. In the first year after sowing, they all form single-clove garlic. They need not be discarded. In the second year, continue sowing the single-clove garlic. Only then can the garlic be rejuvenated and produce normal, high-quality garlic bulbs and garlic scapes.

2.5 Timely topdressing

Fertilizer for garlic should be heavy early and light later. During the growth of garlic leaves, fertilizer and water management should be strengthened, with more fertilizer applied before overwintering as the main focus. In addition, two main topdressing stages must be grasped: first, the seedling-promoting fertilizer. After spring warms up, apply nitrogen fertilizer and potassium fertilizer, and apply them heavily to promote early garlic leaf growth; second, the bulb-promoting fertilizer. Apply it after the garlic bulbs begin to swell to promote bulb expansion. When topdressing, avoid using overly concentrated manure to prevent pests and diseases.

2.6 Improving cultivation conditions

Choose loose, fertile soil for cultivation, plant appropriately sparsely, expand the nutritional area of the plants, and try not to select or collect seed from continuously cropped fields.

2.7 Changing cultivation methods

Using plastic film mulch, planting can be carried out in mid-to-late October, and the plastic film can be laid in mid-to-late November. Since topdressing is inconvenient later, fertilizer should be applied all at once, then the soil should be plowed and beds made for planting cloves. For herbicides, acetochlor and similar products can be selected. Finally, lay the film and press it down, which can increase temperature, preserve soil moisture, and improve the microclimate.