Physiological diseases of lily

Physiological disease, also known as abiotic disease, refers to the disorder of normal physiological metabolism caused by factors other than pathogens. The causes of physiological disorders may be due to internal factors such as lack of mineral elements, tissue aging, or environmental factors such as temperature, luminosity, abnormal gas composition and so on.

I. Leaf burn disease

The typical symptoms of leaf burning are the formation of semicircular gangrene at the tip edge of the leaf, sometimes the formation of yellowing or gangrene at the edge of the leaf or yellow-green spots on the undeveloped or unfolded young leaves, and sometimes white spots.

The symptoms of annular albinism were often seen in the apical leaves of Asian hybrid lilies, while in oriental hybrid lilies, they were damaged at the end of the leaf expansion, and the leaves were constricted in the middle, and the symptoms ranged from albino spots to browning spots. If the leaf burns slightly, the crop can still grow. if it is so serious that the albino spot turns into brown spot, the leaves there will curl. In more serious cases, all the leaves and young buds will be damaged, and the plant will stop growing.

Since the pathogen can not be isolated from leaf burning, it is generally considered that it may be related to fluoride pollution and low pH value. It is considered that leaf burning can be avoided by avoiding fluoride pollution sources such as superphosphate fertilizer and controlling pH up to 6.0 ~ 7.0.

Generally speaking, when the nitrogen fertilizer is too much, the water content is too high, the root growth is poor, the soil salt content is high, and the stem and leaf growth of the plant exceeds the root development, the incidence of leaf burn increases, and the big ball is more prone to leaf burn than the small ball.

The ways to prevent leaf burning are as follows:

1. Do not choose sensitive varieties, and do not choose more sensitive balls if you cannot avoid them.

2. Before planting, wet the soil, select the bulb with good root system and give it deep planting.

3. In sunny days, shading or sprinkling water should be taken to Dow evaporation, and moisture control should be made in the period of increased sensitivity to prevent the spread of greenhouse temperature and air humidity, and try to maintain the relative humidity at about 75%.

4. Rapid growth should be avoided as far as possible. For sensitive Asian lily hybrids, the greenhouse temperature should be maintained at 10: 12 ℃ in the first four weeks, and 15 ℃ in the first six weeks for oriental lily hybrids.

5. Pay attention to fertilization, especially to avoid the pollution containing fluoride, adjust the pH value and EC value to make the pH above 6.

6. The diseases and insect pests that will harm the roots should be effectively controlled.

Second, blind buds, eliminating buds, falling buds

The causes of blind bud, bud elimination and bud drop are mainly related to variety, bulb preparation, cultivation temperature and luminosity. Generally speaking, the longer the forced dormancy refrigerated ball is stored, the higher the probability of blind bud, bud elimination and bud drop after planting in the future.

In the case of Asian-type lily, if the temperature is not well controlled during long-term storage or extended storage and transportation, which results in flower bud differentiation before planting, and the short shrinking stem protrudes more than centimeters of bulbs before planting, or delayed planting, it will cause problems such as blind buds, falling buds and obstruction of Internode elongation. In the early stage of flower bud differentiation, the high temperature (more than 25 ℃) not only reduced the number of flowers, but also prone to blind bud or bud elimination, especially the upper limit temperature of most varieties of Asian type lily was 28 ℃, the buds dropped seriously at 30 ℃, and the blind buds occurred at high temperature above 30 ℃. Similarly, when cultivated at high temperature above 30 ℃, the bud stopped developing at about 3 mm, resulting in stunted individuals.

Generally speaking, the effect of low temperature in the early stage of flower bud differentiation is small. Once the bud is exposed and not fully developed, the phenomenon of bud elimination or bud drop will easily occur when it is encountered at low temperature. For lily, buds below 1 cm will disappear after 20 days when the night temperature is 8 ℃. When the bud is 2 cm and the low temperature is about 9 ℃, the bud will be stunted and abnormal flowers will increase. Even if the flower bud above 6cm keeps the temperature of 13 ℃ in the day and 0 ℃ at night, there is no abnormal phenomenon after 40 days, that is to say, from budding to before the bud reaches 6 cm, abnormal flowers are easy to occur if they are exposed to low temperature, so the temperature management in this period is particularly important.

Therefore, in order to prevent the failure of flower bud differentiation and development, the bulb should be avoided, and the sprouting bulb should not exceed 3 cm. During the cultivation period, try to keep the daily temperature below 25 ℃ and the night temperature 15 ℃ to avoid high temperature and strong light above 25 ℃. For high temperature sensitive Asian varieties, summer planting needs cooling facilities, such as evaporation) and shading, to control the temperature below 28 ℃, which can effectively reduce the bud drop rate. As for ethylene gas pollution, including budding caused by excessive ethylene production during adversity, ethylene inhibitors can be used to reduce the budding problem (Mason,1991). In addition, stress-resistant varieties can be selected from breeding.

Third, sunburn

Sunburn refers to the phenomenon of being burned by the sun. It usually occurs on leaves and buds, and when the dew or irrigation water is not dry, the cells of plant tissue die because of high temperature under intense sunlight. The symptom is that the leaf tissue often forms uniform albinism on the sunny side, and the browning burn marks on the sunny side of the bud. The preventive method is to set up a shading net. Do not carry out sprinkler irrigation in strong sunlight.

IV. Lack of trace elements

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