Thunberg fritillary (Latin scientific name: Fritillaria thunbergii), a perennial herb. The bulb is hemispherical, 1.5-6 cm in diameter, with 2-3 fleshy scales. The stem is single, erect, cylindrical, 50-80 cm tall. Leaves are sessile; the lower stem leaves are opposite, rarely alternate, narrowly lanceolate to linear, 6-17 cm long, 6-15 mm wide; the middle and upper leaves are often in whorls of 3-5, rarely alternate, with shorter blades and tendril-like tips.
I. Grading of Thunberg Fritillary Seed Bulbs
When harvesting Thunberg fritillary, the bulbs are divided into four grades according to size. The largest is called tubbei, with a diameter of 4.5-6 cm; grade two bulbs have a diameter of 3-4.5 cm; grade three bulbs have a diameter of 1.5-3 cm; grade four bulbs have a diameter below 1.5 cm; broken or smaller ones are called jiaohuo. Generally speaking, tubbei and grade four bulbs are both directly used as commercial products, grade two bulbs are used as seed stock for seed fields, and grade three bulbs are used as seed stock for commercial fields; sometimes grade three bulbs can also be used as seed stock for seed fields. The seed stock should be uniform in size, with plump buds, tightly closed scales, and free from pests and diseases.
II. Planting Time for Thunberg Fritillary
In Zhejiang production areas, planting is generally carried out from mid-September to late October, lasting about one and a half months in total. In Jiangsu production areas, mid-September to early October is suitable. Planting time should not be too late; if planting is delayed until after November, root growth will be poor, plants will be short, leaves small, and secondary stems poorly developed, resulting in reduced yield. When planting, seed fields are planted first, with digging and planting done in succession, and commercial fields are planted afterward.
III. Planting Methods for Thunberg Fritillary
On properly prepared land, dig holes for planting according to the requirements of Thunberg fritillary seed fields and commercial fields as well as the different grades of seed bulbs. Place one seed bulb in each hole with the bud center facing upward, then cover with soil, then spread a layer of decomposed dry manure, press lightly, and cover with grass. For seed fields, the row spacing is 20-24 cm and the plant spacing is 16 cm; it is best to plant 15000-16000 plants per mu, with a planting amount of 400-500 kg per mu; large bulbs may exceed 500 kg. For commercial fields, tubbei is best planted at a plant spacing of 20 cm and row spacing of 23 cm, with 12000-13000 plants per mu, and a planting amount of 450-600 kg per mu; grade three bulbs are best planted at a plant spacing of 14-16 cm and row spacing of 20 cm, with 17000-19000 plants per mu, and a planting amount of 350-400 kg per mu; grade four bulbs are best planted at a plant spacing of 14-15 cm and row spacing of 17-20 cm, with about 20000 plants per mu, and a planting amount of 250-300 kg per mu; jiaohuo is sown in furrows in rows, then spread evenly with a certain plant spacing.
IV. Planting Depth for Thunberg Fritillary
Thunberg fritillary should be planted deeper in seed fields and shallower in commercial fields. In seed fields, the planting depth for grade two bulbs is about 10 cm. Deeper planting in seed fields can make the bulb tissue dense, the scales hold each other tightly, and reduce scale scattering and damage to the heart buds during lifting and planting; more importantly, deep burial of bulbs in the soil can reduce the adverse effects of high summer temperatures.
For commercial fields, the planting depth for Thunberg fritillary is 7-8 cm for tubbei, and 5-7 cm for grade three and grade four bulbs. Shallower planting in commercial fields is beneficial for bulb enlargement and increased yield; the scales do not close tightly, and it is also convenient to remove the fritillary heart during processing.
V. Intercropping
From planting to emergence, Thunberg fritillary takes 3-4 months. In order to make full use of the land and fertility, vegetables and other crops can be intercropped in seed fields. The intercropped crops must be harvested before the Winter Solstice so as not to affect the growth of Thunberg fritillary. The method is to plant shallow-rooted plants on the bed surface after planting Thunberg fritillary each year, such as radish, pea, taro, potato, eggplant and other vegetables; peanuts, corn and other crops can also be intercropped. Thunberg fritillary can also absorb and utilize part of the fertilizer applied to those crops, and after the crops are harvested, additional fertilizer is applied specifically to Thunberg fritillary.