Production and Cultivation Techniques for Oriental Lily Cut Flowers in East China
Cut flower lilies are a premium type of fresh flower and are currently among the most popular and best-selling cut flowers in the world. The following introduces the production and cultivation techniques for Oriental lily cut flowers in East China.
Oriental lilies belong to the subclass Monocotyledoneae, family Liliaceae, genus Lilium, and are perennial herbaceous plants. They prefer a cool, humid climate with ample light, and grow with appropriate shading and ventilation. The optimum growing temperature is 8°C to 25°C. They require loose soil, low salinity, and good water retention and drainage.
In East China, such as in Shanghai and other places, summers are hot with strong light, while winters are dry and cold with weaker light, so under traditional natural conditions it is very difficult to achieve year-round lily production and obtain high-quality cut flowers. Generally, protected cultivation is required, such as using greenhouses, cold storage, heating boilers and other facilities. Because the early rooting stage of Oriental lilies is very sensitive to high temperatures, planting from June to September should be avoided as much as possible in East China, especially soil cultivation, as high soil temperatures will seriously affect the quality of lily cut flowers. Oriental lily production can use soil cultivation or substrate cultivation, and substrate cultivation has two types: box cultivation and raised bed cultivation.
Cultivation Steps
(1) Thawing. Oriental lilies planted in East China mainly use imported Dutch bulbs, and Dutch bulbs are generally shipped in boxes in a frozen state. After the bulbs arrive, they should be planted as soon as possible within a short time. Frozen bulbs need to be slowly thawed before planting, generally by opening the box lid and plastic packaging bag and placing them at 10°C to 15°C. Never place them under direct sunlight or at high temperatures. After thawing, the bulbs must not be frozen again, otherwise freezing damage will occur. If temporary storage is needed, they can be placed at 0°C to 2°C for up to two weeks, or at 2°C to 5°C for up to one week, with the packaging bag opened to prevent the temperature inside the box from rising rapidly. High-temperature storage and prolonged storage will cause premature sprouting and affect bulb quality. Pay attention to the moisture of the packaging medium, otherwise the bulbs will dehydrate and dry out, which will shorten the main stem of the lily and reduce the number of flower buds.
(2) Making raised beds. The soil should first be plowed and finely leveled, and the drip irrigation system (drip lines) installed in place. Then make raised beds and set up nets. The bed width is generally 1 to 1.2 m, and preferably not more than 1.4 m, otherwise it is inconvenient for planting and harvesting operations. For the support net, generally a metal net or plastic net of the same width as the bed is used, with grid squares usually 12 to 14 cm on each side. The support net needs to be fixed with posts, usually 1 post every 2 to 4 m. The posts can be thin iron pipes or thin bamboo poles, etc., but they must have a certain length, with a height above ground of 80 to 100 cm, so that the support net can be raised upward.
(3) Density. Planting density varies with variety, bulb size, season, soil type, etc. Generally, in winter when light is poor or under high-temperature conditions, the density should be lower. In heavy clay soil, such as peat soil, plants grow quickly, so the density can also be reduced. Table 1 shows the minimum and maximum planting densities per square meter for different sizes of Oriental lily bulbs.
(4) Planting. Factors such as the workers' planting speed, the greenhouse environment of the day, the arrangement of varieties, and the planting tools used should be considered. The greenhouse should be adjusted to conditions of shading, appropriate ventilation, and relatively humid conditions. Carefully remove the thawed bulbs from the packaging bags, try not to damage the root system, and plant them into the soil as soon as possible to prevent a decline in bulb quality caused by dehydration. A small planting trowel can be used to dig soil and plant the bulbs. The bulbs must be planted at sufficient depth in the soil, generally with a soil layer above the bulb of 6 to 8 cm in winter and 8 to 10 cm in summer, to benefit the later growth of stem roots. Note that the covering soil should keep the soil loose to benefit root growth. After planting, appropriate materials such as rice husks or straw can be used to cover the soil, which can play a role in heat insulation, moisture retention, and preventing deterioration of soil structure. A better method is to cover with a 2 to 3 cm thick layer of moist peat soil, which gives relatively good results.
Environmental Control and Management
(1) Irrigation. A combination of top sprinkler irrigation and bottom drip irrigation can be used. Generally, top sprinkler irrigation is used before the flower buds can be seen, and once the flower buds appear, it can be switched to bottom drip irrigation. Whichever irrigation system is used, it must distribute water evenly. A sprinkler irrigation system helps to spray water evenly and, to a certain extent, increases relative humidity and lowers temperature. In addition, the raised bed must have a good drainage system so that excess water drains away quickly. The amount of watering is determined by soil type, greenhouse climate, cultivated variety, plant growth status, etc. Because lilies have stem roots growing in the upper soil layer, the upper soil must always remain appropriately moist. Watering should be done immediately after planting and should be thorough, so that the soil and bulbs can fully and closely combine, which benefits root growth. A general method for checking soil moisture is to tightly squeeze a handful of soil in the hand; if a few drops of water can be squeezed out, it indicates that the moisture is appropriate.
(2) Temperature and relative humidity. The temperature required by Oriental lilies varies with growth stage, etc. During the first one-third of the lily's growth cycle (or at least before the stem roots emerge), the temperature (including soil temperature) should be as low as possible to benefit the growth and development of stem roots, with the optimum temperature being 12°C to 13°C. Too low a temperature will prolong the growth period, while a temperature above 15°C will lead to a decline in lily flower quality. During the remaining growth period, the daily optimum temperature for Oriental lilies is 15°C to 17°C. If it is below 15°C, it may cause bud drop and yellow leaves. Usually, the night temperature can be controlled at 15°C to 16°C and the daytime temperature at 17°C to 18°C, but care should be taken to avoid too large a difference between day and night temperatures. Generally, greenhouse temperature is regulated through measures such as ventilation, shading, and heating. Cultivation temperature requirements for Oriental lilies
The relative humidity requirement is between 75% and 85%. Sudden changes in relative humidity should be prevented, as this may cause leaf scorch in some sensitive varieties. Oriental lilies are the most prone to leaf scorch, generally occurring before flower buds appear. Symptoms are that young leaves curl slightly inward, then small yellow-green to white spots appear on the leaves, after which the leaves bend and begin to rot. In severe cases, young buds and leaves drop off, and plant growth almost stops. The causes are drastic changes in greenhouse relative humidity, high humidity, lack of ventilation, or poor lily root systems, high soil salt content and other factors, which can disrupt the balance between water uptake and transpiration in the plant and cause calcium deficiency in leaf cells.