First, the reasons: 1, the normal physiological phenomenon. The absorption root of garlic in seedling stage changes from longitudinal growth to lateral growth, and absorbs nutrients and water for plant growth and development. Functional leaves grow continuously for photosynthesis to produce nutrients, and plant growth also gradually transitions from nutrient-dependent nutrition to photosynthetic nutrition. . During this period, the mother's valve gradually shrinks due to nutrient depletion, until the film is dried up, this process is called "recessed mother" or "rotten mother." During the period of retreat, garlic buds and flower buds are in the differentiation phase and require a lot of nutrients. At this time, the nutrients in the mother's petal have been exhausted and the plants are still not adapting to self-cultivation. Therefore, the supply of nutrients is in a state of disrespect between the yellow and the yellow. On the plants, the tips of the first to fourth leaves were yellow, a phenomenon called "dry tip." Therefore, "dry tip" is a kind of growth transition of garlic plants, not less fertilization, and it is not caused by diseases.
2, the impact of abnormal climate. Garlic is a cold vegetable, the suitable temperature for the growth of stems and leaves is 12 ~ 16 °C, when the temperature reaches above 26 °C, the leaves are vigorous, the water transpiration is large, nutrient consumption is more, then the yellow leaves at the top of the plant's upper leaves, from The tip of the leaf gradually develops toward the base, and the dry tip appears. In case of dry hot air, the damage to the blades is even heavier. The earlier it occurs, the heavier the damage.
3, the impact of cultivation measures. The root system of garlic is a hi humid root system. The distribution range of fibrous roots is small, and the requirements for water and fertilizer are relatively high. The soil is too dry or too wet and the fertility is insufficient. In addition, the planting of heavy crops, the density is too large, lack of nitrogen or potassium fertilizers are also prone to yellow tip phenomenon. The yellow tips produced by this reason are more common in production and often occur on the upper leaves of the plants.
4, garlic degradation or infection. Due to the garlic's long-term use of garlic cloves for vegetative propagation, garlic is degraded, its growth potential is reduced, its ability to resist diseases and its ability to adapt to adverse environments is reduced. If improper cultivation measures are encountered, yellow leaves are produced, premature aging occurs, and garlic sprouts and garlic are seriously affected. Yield and quality.
Second, prevention and control measures: For the reasons for the occurrence of the above-mentioned yellow leaf tip, the following preventive measures can be taken:
1, selected excellent species. Select garlic hypertrophy, complete bottom buds, top buds are fat, white color, no wounds, no lesions of garlic seeds do species. According to the survey, under the same fertility and management level, the size of garlic is directly proportional to the output. The large garlic clove, the garlic mother are more nutritious, the plants are strong, and the stress resistance is strong. The garlic sprouts are thick and the garlic head is large and the yield is high.
2, purification and rejuvenation. The establishment of garlic seed fields or the breeding of aerial bulbs will restore the species of garlic and increase its viability. It is also possible to culture stem tips to cultivate non-toxic virus-free garlic.
3, carefully cultivated. (1) Choose sandy loam with loose soil and high fertility, and apply 4000 kg of farmland fertilizer before planting. (2) 100 kilograms of plant ash in the seedling stage will not only prevent the soil from cracking and damage the garlic roots, but also increase the potassium fertilizer. (3) In the early stage of the mother's retreat, foliar spray of chitin + foliar fertilizer and amino acid foliar fertilizer can be applied to increase the resistance of the plant; if the organic fertilizer is applied before the seed is applied, the topdressing nitrogen fertilizer can also be applied before the mother is retired. Reduce dry tip hazards. (4) Grasp the season of garlic sprouts and maintain the maximum water holding capacity of 60% to 70% in the field. Otherwise, the soil is too dry and too wet to easily produce yellow tips. (5) In the early growth stage of garlic sprouts, regular spraying foliar spray, Phytophthora blight, potassium dihydrogen phosphate, etc. are used to improve stress resistance. Before 10 to 15 days of rotten mothers, 10 kg of urea was applied to ensure the absorption of roots during this period. (6) Spray water at high ambient temperature, night and night temperature difference, day and night, supplement water or spray 150 mg/kg sodium bisulfite, inhibit plant nutrient consumption, reduce evaporation of leaf water, ease the harm of dry hot wind, delay yellowing of leaves And premature aging of plants. (7) Root rot in garlic leaf blight areas can also cause garlic tip, and it is recommended that vegetable farmers have specific prevention and treatment according to actual conditions.
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