Effect of boron deficiency on symptoms and prevention of boron deficiency in flowers, leaves and fruits of pomelo

In recent years, there are different degrees of boron deficiency in pomelo, which affects the quality of pomelo. According to many years' practice, the correction of boron deficiency in honey pomelo should be based on strengthening cultivation management, increasing organic fertilizer, paying attention to balanced fertilization and soil testing fertilization, spraying boron fertilizer and replenishing boron supply outside the root.

Symptoms of boron deficiency in honey pomelo

Symptoms of boron deficiency:

1. Leaves: the new leaves show yellow water spots and deformities; the old leaves are bronzed, the leaves are slightly curled and brittle, and when boron deficiency is serious, the leaves of pomelo turn yellow, and the midrib and lateral veins of leaves are swollen or even burst.

2. Flowers: dysplasia of floral organs, many deformed flowers and dew-styled flowers, poor flower quality, serious flower drop, poor pollination and fertilization and low fruit setting rate.

3. Fruit: the young fruit is deformed, and the pericarp has tumor-like protuberances, often accompanied by brown glue, and the fruit drop is serious. There is obvious rupture of fruit stalk, russet gelatinous substance can be seen in the pericarp spongy layer of honey pomelo section, and hard and stiff fruits often appear. The expansion rate of honey pomelo is slow. During the growth stage, the peel of honey pomelo was rough, thickened and slightly corked, showing unequal yellow patches. During the mature period, the sponge layer of the core and pericarp has the characteristics of brown colloid deposition, poor coloring, low edible rate, less juice, low sugar content, poor flavor and not resistant to storage.

2. Corrective techniques

1. Deep ploughing to improve the soil, increase the application of organic fertilizer, combined with the application of honey pomelo special fertilizer. Cover weeds inside and outside the canopy, keep the soil moist, cultivate strong trees and developed roots, and improve boron absorption and utilization.

2. Boron-deficient pomelo trees can be sprayed outside the roots with 50 kg of water plus 50 grams of boric acid or 100 grams of borax, 150 grams of urea and 200 grams of magnesium sulfate and 150 ml of Xinye flower and fruit nutrient solution during flowering and young fruit stage. According to the degree of occurrence, 2 Mel was sprayed outside the root 4 times a year.

3. When the content of water-soluble boron is less than 0.4 and the pH value is lower than 4.5, the soil can be turned over in winter, 1.5 kg borax per mu can be applied, and 50 kg lime can be added to acid and calcium per mu, so that the soil pH value can be kept at 5MUE 6.5, so as to promote the absorption and utilization of boron by honey pomelo roots.

4. girdling to promote flowers should be carried out according to the tree potential, climate and soil conditions, so as to make the wound heal on time and avoid affecting the absorption of boron. The ring peeling width of pomelo tree with strong tree strength and mild climate and sufficient soil moisture is 3mm 5mm. In other cases, it should be less than 3mm or be replaced by spiral ring cutting 2 times.

5. Jinguang chrysanthemum is a boron-rich green manure, which can be planted in the ridge and grass belt of pomelo orchard as a source of green manure. In production, increasing the application amount of green manure can increase the supply of boron.