Occurrence and control of hollow in main stem of broccoli

The main stem of broccoli is hollow, but does not rot, and is formed due to physiological disorders. If the selection of varieties and improper planting management, resulting in plant physiological imbalance, which will form a hollow, seriously affect the quality and commodity value of the commodity bouquet, and cause losses. The main results are as follows: 1. the hollow symptom of the main stem is mainly formed in the mature stage of the curd. At first, several small oval gaps were formed in the stem tissue, and with the growth and maturity of the plant, the small gap gradually expanded and connected into a large gap, so that the stem formed a hole, and in severe cases, the cavity extended to the flower stem. The surface of the cavity is lignified and brown, but does not decay, and the pathogen can not be detected from discolored tissue. Second, the reasons for the occurrence of hollow in the main stem 1. In planting, the row spacing is too large and the nitrogen fertilizer is applied too much, especially in the corm growth period, the plant grows too fast, which is easy to cause the occurrence of hollow. 2. Lack of water or improper watering in vegetative growth period and heading period can easily lead to the occurrence of empty stem. 3. Broccoli is a kind of cool-loving crop, and the suitable growth temperature is 15-22 ℃. If the planting season is not arranged properly, the high temperature (above 25 ℃) will make the bulb grow too fast and easily cause hollow. 4. The serious boron deficiency in the field can induce the change of the tissue cell wall structure in the stem, degenerate the tissue in the stem, and accompany the Lignification process, resulting in the formation of hollow. 5. There are some differences in the susceptibility of different varieties to hollow. Some varieties have wide adaptability, not easy to hollow, and some varieties are easy to hollow. Third, prevention and control measures 1. Select varieties that are not easy to be hollow. 2. Sowing seeds at the right time, cultivating strong seedlings, planting at the right time, and staggering the flower heads to meet high temperature during the growing period. 3. Reasonable close planting according to the characteristics of the varieties used. The suitable plant spacing is 30cm to 45cm and the row spacing is 60cm to 70cm. 4. Fertilizer and water management. Water management: to keep the soil dry and wet, it is generally required to irrigate 1 water every 5-7 days. Fertilizer management: in the case of sufficient base fertilizer, the amount of phosphorus and potassium fertilizer can be increased with watering 6 kg / mu of nitrogen fertilizer, a small amount of multiple times as the principle. For boron deficient soil, 0.5 kg boron fertilizer per mu was applied as base fertilizer, and then 0.5 kg was used as topdressing or root irrigation. 5. Timely harvest. It can be harvested in 10-15 days from the current bouquet. The early flower bulb is not fully grown, the yield is low, it is easy to form an empty stem too late, and the flower ball is easy to be loose, withered buds and lose its commercial value.