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First, the occurrence of empty stems Symptoms of empty stems are mainly formed during the mature period of the flower bulbs. Initially, several small oval-shaped nicks were formed in the stem tissue. As the plants matured, the small nicks gradually enlarged and connected to form a large gap, which formed a hollow cavity in the stem, and the severe time-space expanded to the stem. The surface of the cavity is lignified and becomes brown, but it does not decay, and no pathogen can be detected from the discolored tissue. The presence of empty stems can be observed by cutting the bulbs and stems longitudinally or by cutting stems 15 to 17 cm below the top of the bulbs.
Second, the reasons for the occurrence of empty stems Broccoli empty stems by the planting density, excessive nitrogen fertilizer, water shortage, lack of boron, high temperature and other factors caused by physiological disorders.
1. Planting density Increased plant spacing, plant growth rate, and high incidence of empty stems.
2. The excessive application of nitrogenous nitrogen fertilizer, especially in the growth period of the flower bulb, makes the plant grow too fast and the incidence of empty stems is high.
Watering broccoli is a kind of multi-sap crop, which requires a certain amount of soil moisture. The lack of water or watering in the vegetative growth period and the growth period of the flower bulb can easily cause the occurrence of empty stems.
4. Temperature Broccoli is a kind of cool crop, suitable growth temperature is 15 ~ 22 °C, such as improper planting season, high temperature (25 °C above) in the flower bulb growth period, so that the bulbs grow too fast, easy to cause Empty stems.
5. Boron test has proved that the empty stem of broccoli is related to boron deficiency. Under the condition of boron deficiency, the structure of cell wall in the stem can be induced to change, and the tissue in the stem is degraded, and the process of lignification is accompanied by lignification.
6. The susceptibility of different varieties of broccoli to empty stems is somewhat different. Some varieties have wide adaptability, they are not easy to empty stems, some varieties are easy to empty stems, and empty stems are heritable, empty stems do not empty stems. Partially dominant.
Third, prevention and control measures
1. Selection of varieties that are not easy to empty stems This is one of the most effective methods for the control of empty stems. The varieties that are not easy to empty stem include the jasper varieties developed by the Beijing Vegetable Research Center, the series of varieties of the Japanese Peony Company, and the green belts, landscapes, and jades. Crown and other varieties.
2. Arrange suitable planting time When arranging broccoli, avoid high temperatures during the growth period of the flower bulbs. Therefore, according to the growing period of the selected varieties, it is required to sow at the right time, cultivate strong seedlings, and plant timely.
3. Reasonable dense planting according to the characteristics of the species used, close planting. Generally speaking, the suitable spacing is 30-45cm and the spacing is 60-70cm.
4. Fertilizer and water management Planting broccoli should select well-drained and well-prepared plots and conduct soil nutrient determination before planting so as to determine the type of fertilization and the amount of fertilizer to be applied.
Management has always maintained that the soil is dry and wet. In the spring and spring planting seasons in the north, it is generally required to pour water every 5 to 7 days. Although it is necessary to apply a certain percentage of nitrogen fertilizer for the normal growth of broccoli, excessive nitrogen fertilizer should be avoided during the growth period of broccoli. In the case of applying composted compost as a base fertilizer, 13 kg of nitrogen fertilizer may be applied with every 1000m2 of watering. The principle of a small number of times shall be used. Fertilizers in the growth phase of flower bulbs shall have little or no nitrogen fertilizer and increase the application amount of phosphorus and potassium fertilizers. .
For boron-depleted soils, apply 0.75 kg of boron fertilizer per 1000 m2 as the base fertilizer, and then use 0.75 kg as top dressing or rooting.
5. The harvested broccoli product organ is a flower bud that has already formed a bud. If the early flower bulb is not fully grown and harvested, the yield is low, and the empty stem is easy to be formed too late, and the flower bulb is easy to loose, and the buds are lost. Value, so it must be harvested in due course. Generally speaking, it takes 10 to 15 days from the present time to the harvest. The harvesting standard is the horizontal diameter of the flower bulb 12 to 15 cm. The flower bulb is tight and the buds are not yellow or necrotic.
Occurrence and Control of Empty Stem of Broccoli
The empty stem or hollow of broccoli refers to the hollow stem of the main stem of the commercial flower bulb, but it does not rot and is formed due to a physiological disorder. Empty stems are a poor commercial character. Markets, especially foreign markets, require commodity stems without empty stems. If improper selection and planting management result in plant physiological disorders, the plants will form empty stems, which will seriously affect the quality and value of commercial flower bulbs, resulting in huge losses.