I. Symptoms:

Boron deficiency symptoms occur in the apical growth point, young leaves, tuberous stems, or fruits and other tissues in the growth and development of the symptoms vary from crop to crop, in summary:

(1) the apical growth point and the heart of the leaf growth is hindered, whitening or browning and necrosis, to stimulate the growth of side shoots (part of the side shoots are also necrotic) and the clumps or clusters of the shape.

(2) Leaf deformity, thickened and fragile or wrinkled and curled, and some crops have intervein yellowing symptoms.

(3) Thickening of petioles or stems to short and thick, cracked and corky, or water-soaked gangrene.

(4) Corking or black heart in tubers or stems.

(5) Boron deficiency inhibits pollen and nectar formation and pollen tube development and affects pollination, resulting in severe flower or fruit drop.

(6) Fruit deformity, slow development, localized water-soaked skin or pulp, thickening of the skin, low juice rate, poor seed development.

Two, easy to occur in the environmental conditions:

(1) rainfall-rich areas of the riverbed, gravelly, sandy soil or red soil, because of the long-term drenching effect of the soil boron content is very low, the crop is prone to boron.

(2) high acidity and alkalinity of calcareous soil, boron is easy to be fixed, low effectiveness, and cause crop boron deficiency.

(3) drought, boron movement in the soil and crop uptake are blocked, more prone to boron deficiency.

(4) Preferential application of nitrogen fertilizer aggravates boron deficiency.

(5) Planting sensitive crops. Dicotyledonous plants are more sensitive than monocotyledonous plants, and fruit and vegetable crops are generally more deficient in boron than field crops. Field crops in rape, sugar beet, sunflower, sesame, cotton; fruit and vegetable crops in citrus, apples, grapes and kale, cabbage, celery sensitive to boron. Grain crops in addition to wheat, corn is generally not sensitive to boron.

Three, prevention and control methods:

Soil application of boron fertilizer is commonly used. Used as boron fertilizer, borax, boric acid, boron mineral mud, etc., but borax is commonly used. General dosage of field crops 7.5 ~ 15 kg / ha, large boron demand, such as sugar beet 22.5 ~ 30 kg / ha, mixed with mud or water, spraying with 0.1% ~ 0.2% borax liquid, dosage per hectare 750 ~ 1500 grams; fruit trees according to the application of the tree, 50 ~ 100 grams per tree.

Since the general crops containing boron suitable for a narrow range of appropriate, appropriate and excess boundaries close to the limit, it is very easy to overdose, so the dosage should be strictly controlled; in fact, it is a slow dissolution of borax, should be used to promote the dissolution of warm water, and then to the full amount of water application.

In addition, to control the soil too alkaline, fertilization should focus on the choice of acidic fertilizer.