What are the reasons why tuberose does not bloom?
Tuberose is what we commonly call night-blooming jasmine. Because tuberose has very high ornamental value and its habit of blooming at night is deeply loved by flower enthusiasts, many friends often encounter the situation where tuberose does not bloom during the process of growing it. So exactly what causes tuberose not to bloom? And how should it be handled?
Tuberose
1. Improper storage
If tuberose tubers are stored improperly in winter, affected by moisture and freezing, the main flower buds inside the tubers suffer cold damage or rot, so planting the following year also fails to produce flowers. Although there are secondary flower buds inside the tubers, the growing season is too short, and before they can emerge the frost period has already arrived. Therefore, if you want tuberose to bloom, you should fully dry the tuber skin in the sun and then store them in a dry, warm place to prevent the main flower buds from rotting. In addition, you should plant early and harvest as late as possible.
2. Digging up the bulbs too early
Digging up the bulbs too early is also a cause of tuberose not blooming, because digging up the bulbs too early affects the formation of flower buds inside the tubers, causing them not to bloom the following year. Therefore, as long as they will not suffer cold damage, dig up the bulbs as late as possible. This is one of the measures to increase the flowering rate of tuberose.
3. Planting tubers that are too small
Generally, tuberose tubers must grow to a diameter of more than 2.2 cm before flower buds can form inside and bloom. If the tuberose planted is a small tuber, smaller than 2 cm, it has not reached flowering age and tuberose will not bloom either. Therefore, when planting, to encourage large bulbs to bloom you can plant them shallowly, so that the entire terminal bud is exposed above the soil surface; to encourage small bulbs to enlarge you should plant them deeply, covering with soil so that only the tip of the young shoot is exposed.
4. Excessive fertilization
Another main reason tuberose only grows leaves without blooming is excessive fertilizer and water, especially too much nitrogen fertilizer, which leads to excessive vegetative growth, that is, excessive stem and leaf growth, which inhibits flower bud growth and results in few or even no flowers. Therefore, during the vegetative growth period, the concentration of fertilizer applied should be strictly controlled, especially the amount of nitrogen fertilizer. This is an important technical measure to prevent tuberose from only growing leaves without blooming.
Causes and solutions for tuberose only growing leaves without blooming
Tuberose is what we call night-blooming jasmine or moonflower. Because its fragrance is especially strong at night, this unique characteristic makes people love it very much. Because tuberose is relatively easy to cultivate and its flowering period is easy to control, it is also one of the more important cut flowers. But if you encounter tuberose only growing leaves without blooming, it means there is a problem. The editor will analyze for you the causes and solutions for tuberose only growing leaves without blooming.
Tuberose
1. The flower buds of tuberose are already formed on the bulb in the previous year. It may be that a small tuber was planted, which had not reached flowering age, so it cannot bloom. Generally, the diameter of a tuberose bulb must reach more than 2.2 cm, and the inflorescence primordium has already formed inside in the previous year, so it can bloom only after planting.
2. Digging up the bulbs too early affects the differentiation of flower buds inside the tubers, so that planting the following year cannot produce flowers.
3. Digging up the bulbs too late or improper storage of the tubers in winter, with temperatures too low and exposure to moisture and freezing, causes the flower buds inside the tubers to suffer cold damage or rot, so planting the following year also cannot produce flowers.
4. Applying excessive nitrogen fertilizer leads to excessive stem and leaf growth, with few flowers, and in severe cases even no flowers at all.
In response to the above causes, when planting tuberose you should choose large tubers and plant them in April to May each year as needed. At the same time, during management you should apply less nitrogen fertilizer and more phosphorus and potassium fertilizer.
Comparison of cold resistance of spider lily, autumn zephyr lily, red spider lily, and tuberose, plants of the Amaryllidaceae
Abstract: By measuring the morphological indicators and several physiological indicators of the leaves of four Amaryllidaceae plants - autumn zephyr lily, red spider lily, tuberose, and spider lily - as well as their freezing damage under simulated low-temperature treatment, the differences in their cold tolerance were studied. The results show that the order of cold resistance is: autumn zephyr lily > red spider lily > tuberose > spider lily.
Keywords: Amaryllidaceae plants; cold resistance; morphological indicators; physiological indicators; low-temperature simulation
Amaryllidaceae plants have characteristics such as varied flower shapes, rich flower colors, sturdy scapes, and long stems. They have now become world-famous bulb flowers and are an important group of ornamental plants. In recent years, they have attracted the attention of departments or professionals related to landscape engineering and flower breeding. However, because their cold resistance varies greatly, many species with very high ornamental value cannot safely overwinter in the Yangtze River basin and areas to its north. Therefore, studying the cold resistance among these species is of great significance for cold-resistance breeding and cold-resistance cultivation of Amaryllidaceae plants. Scholars at home and abroad have already done a great deal of research on Amaryllidaceae plants from aspects such as morphology, physiological ecology, chromosome karyotype, and tissue culture, but there are still few reports on the changing patterns of cold-resistance physiological substances in leaves and research on their cold resistance. The author measured and analyzed the morphological indicators and physiological and biochemical indicators related to cold resistance of four Amaryllidaceae plants cultivated in the Yangtze River basin - autumn zephyr lily, red spider lily, tuberose, and spider lily - and also used low-temperature simulation tests to determine their cold resistance, in order to judge the degree of cold resistance of these four plants and provide a reference basis for their introduction and cultivation.
1 Materials and methods
1.1 Test materials
Autumn zephyr lily (Zephyranthes candida Herb.), red spider lily (Lycoris radiata Traub.), tuberose (Polianthes tuberosa L.), and spider lily (Hymenocallis Americana Salisb.), planted in the botanical garden of the West Campus of Yangtze University. The growth environment conditions of the four Amaryllidaceae plants, such as light, moisture, and soil fertility, were relatively consistent, and they grew well.
1.2 Test methods
1.2.1 Determination of cold-resistance morphological indicators and physiological indicators. In mid-December 2007, normal leaves from the second layer of plants on the outer periphery of the planting plots of the four plants were randomly picked in the botanical garden. After picking, they were immediately wrapped in moist gauze, placed in sealed plastic bags, and brought back to the laboratory. They were rinsed separately with tap water and distilled water, and the washed leaves were wiped dry with gauze or absorbent paper for later use.
(1) Observation of leaf morphological indicators. The middle section of the leaves was taken and cross-sectioned. Observation was carried out with an OLYMPUS PM-PBM-3 optical microscope at 10×10 magnification. An eyepiece micrometer was used to measure the thickness of the palisade tissue, spongy tissue, and lower compact tissue on the leaf cross-section, and the cell structure tightness (CTR) was calculated. Each species was measured 10 times repeatedly.
CTR (%) = (palisade tissue + lower compact tissue) / leaf thickness × 100
(2) Determination of cold-resistance physiological indicators. The free water and bound water content (extracted with 60% sucrose solution), proline content, malondialdehyde (MDA) content, and peroxidase (POD) activity were determined.
1.2.2 Low-temperature simulated freezing damage test. Leaf preparation: On the afternoon of December 17, 2007, leaves were picked according to the above sampling method, wiped dry, and placed in a refrigerator for cold storage for 24 h. The prepared leaves were first trimmed at both ends with scissors, then cut into segments 2 cm long and mixed evenly. The segments were randomly placed in culture dishes, covered, and arranged evenly, with 5 segments spread flat in each culture dish, and 5 culture dishes for each low-temperature treatment for each plant. Then artificial simulated freezing damage treatment was carried out. The set low temperatures were 0°C, -5°C, -7°C, -9°C, etc. (temperature variation value was ±1°C). Each culture dish was randomly placed in a low-temperature constant-temperature cabinet (model: Haier Aerospace Inverter Refrigerator, Crystal Prince BCD-209BC ZA), and the temperature was gradually lowered. After reaching the required freezing temperature, it was maintained for 1 h. After each temperature stage ended, the culture dishes treated at that stage were taken out. Freezing damage was recorded according to Table 1, and the freezing damage index was calculated.
Freezing damage index (%) = [(∑ number of damaged segments at each level × corresponding representative level value) / (total number of investigated segments × representative value of the highest damage level)] × 100
2 Results and analysis
2.1 Comparison of leaf cell structure
Shu Jilin et al. believed that well-developed tea leaf mesophyll tissue, a high degree of differentiation, large palisade tissue thickness, many layers, tight arrangement, and small cells are anatomical structural characteristics of leaves with strong cold resistance. According to comparative research by Jian Lingcheng et al. on the cell structure of leaves of different citrus species, the tightness of tissue structure - the index of compact tissue (the ratio of the thickness of palisade tissue and lower compact tissue to leaf thickness) - is significantly positively correlated with the cold resistance of citrus species. She Wenqin et al., after studying the relationship between the cell structure tightness of lychee leaves and cold resistance, believed that measuring leaf cell tightness (CTR) reflects the relationship among palisade tissue, spongy tissue, and lower compact tissue, and is more accurate as an indicator than the quantitative change of a single substance or a single structure, and is simple to observe. From Table 2 it can be seen that the differences in leaf cell tightness among autumn zephyr lily, red spider lily, and tuberose are relatively small, but all are significantly greater than that of spider lily.
2.2 Comparison of physiological indicators of leaf cold resistance
2.2.1 Comparison of leaf water content of the four Amaryllidaceae plants. Water in plant tissues exists in two different states: free water and bound water. The relative content of free water and bound water can serve as an important indicator of plant tissue metabolic activity and stress resistance. It is generally believed that the greater the proportion of bound water content, the more cold-resistant the plant. Jin Yanming et al.'s research on peony also concluded that the ratio of bound water to free water can well identify the cold resistance of different varieties. When the ratio of bound water to free water is low, the metabolic activity of plant tissues or organs is vigorous, growth is also faster, and stress resistance is weaker; conversely, growth is slower, but resistance is stronger. From Table 3 it can be seen that the order of the ratio of bound water to free water is: autumn zephyr lily > red spider lily > tuberose and spider lily, among which autumn zephyr lily has extremely significant differences from the other three; red spider lily has significant differences from tuberose and extremely significant differences from spider lily; while the difference between tuberose and spider lily is not obvious.
2.2.2 Comparison of proline content in the leaves of the four Amaryllidaceae plants. Under stress conditions, the proline content in plants increases significantly. The proline content in plants reflects to a certain extent the stress resistance of plants, and the level of proline content can also serve as a physiological indicator of cold resistance. The higher the proline content, the stronger the cold resistance of the plant; conversely, the weaker it is. From Table 3 it can be seen that the proline content of autumn zephyr lily and red spider lily is extremely significantly higher than that of spider lily, but the difference from tuberose is not significant; the difference between tuberose and spider lily is also not significant.
2.2.3 Comparison of malondialdehyde (MDA) content in the leaves of the four Amaryllidaceae plants. Prolonging low-temperature time or strengthening the degree of low-temperature stress destroys the balance between free radical production and scavenging reactions, decreases enzyme activity and antioxidant (Vc) content, damages the defense mechanism, intensifies membrane lipid peroxidation, and causes accumulation of the membrane lipid peroxide malondialdehyde (MDA). Research on the cold tolerance of apricot flower organs shows that MDA content increases as temperature decreases, coinciding with the starting point and inflection point temperatures when plasma membrane permeability rises, and it was found that varieties with strong cold resistance have lower MDA content under low-temperature stress than varieties with weak cold resistance. This indicates that the content of MDA, the most important product of membrane lipid peroxidation, is negatively correlated with cold resistance. From Table 3 it can be concluded that the MDA content of spider lily and tuberose is extremely significantly higher than that of red spider lily and autumn zephyr lily; while the differences between red spider lily and autumn zephyr lily, and between spider lily and tuberose, are not significant.
2.2.4 Comparison of peroxidase (POD) activity in the leaves of the four Amaryllidaceae plants. In research on the relationship between oxidase activity and grape cold resistance, Wang Shujie et al. analyzed the POD activity of 4 grape varieties with different cold resistance and pointed out that POD activity differs among grape varieties with different cold resistance: varieties with strong cold resistance have high oxidase activity and change slowly as temperature decreases; those with poor cold resistance have low enzyme activity and change drastically as temperature decreases. From Table 3 it can be seen that autumn zephyr lily shows extremely significant differences from all the other three plants; red spider lily also has extremely significant differences from spider lily, and significant differences from tuberose; the difference between tuberose and spider lily is not significant.
2.3 Comparison of cold resistance of the four Amaryllidaceae plants under simulated low temperature
Using low-temperature simulation tests, the cold resistance of the four Amaryllidaceae plants can be compared relatively intuitively. In this experiment, the freezing damage indices of the four plants were observed and recorded at 4 temperatures (0±1°C, -5°C, -7°C, -9°C) (see Table 4). It can be seen that spider lily had already suffered freezing damage at around 0°C, while the other plants were at 0, showing significant differences from the other plants. When the temperature dropped to -7°C, the freezing damage index of tuberose was also significantly higher than those of red spider lily and autumn zephyr lily. The freezing damage indices of red spider lily and autumn zephyr lily still showed no significant difference at -9°C. From this it can be inferred that the freezing resistance of these four plants is: autumn zephyr lily and red spider lily > tuberose > spider lily.
3 Conclusion
Through the measurement and analysis of the morphological indicators and physiological indicators of the four Amaryllidaceae plants, as well as low-temperature simulation tests, their degree of cold resistance can basically be determined. The order of their cold resistance is: autumn zephyr lily > red spider lily > tuberose > spider lily.
4 References
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