What to Do About Boron Deficiency in Rapeseed? Symptom Identification and the Latest Control Methods

Rapeseed is grown extremely widely in China, and it is highly sensitive to the element boron. A boron deficiency can seriously affect rapeseed yields, and boron deficiency is quite widespread in most of China's soils. Therefore, applying borax at planting has a clear effect on rapeseed. So what symptoms does boron deficiency in rapeseed cause? How should it be controlled? Let's take a look.

1. Symptoms of boron deficiency

When boron is deficient at the seedling stage, the young seedlings show dark green leaves and shrunken leaf blades; later, purplish-red spots appear, the leaves drop early, and in severe cases the seedlings die. When boron is deficient at the bolting stage, the leaf margins turn red, the leaves become thick and brittle, the top of the main stem withers, stem splitting sometimes occurs, and the flower buds develop abnormally or even dry up and drop. When boron is deficient at the flowering stage, the inflorescence is noticeably stunted, the tip shrivels, flowering is delayed, large numbers of flower buds drop, and the young pods are deformed; in severe cases, no pods set at all. When boron is deficient at the pod stage, flowers appear but no seed sets, the pods contain no seeds or only small, weak seeds and deformed seeds, and the seeds are uneven in size.

2. Causes of boron deficiency

First, boron deficiency is related to the soil: when the soil has poor water-holding capacity, the element boron is very easily lost, causing boron deficiency. It is also related to environmental factors. Studies show that the plant's uptake of the element boron weakens as light intensity decreases; during drought, the transport of the element boron is blocked, which also causes boron deficiency; and when moisture content is high, boron is lost. Boron also has mutually constraining relationships with elements such as nitrogen, phosphorus, and potassium. When the plant's nitrogen content is relatively high, it will take up boron to balance it; generally, boron-deficient plants are found to have higher nitrogen than normal plants. In addition, boron deficiency affects the plant's uptake of phosphate fertilizer, but it can promote the uptake of potash fertilizer. Therefore, when the plant is boron-deficient, potash fertilizer should not be applied, so as to avoid worsening the boron deficiency symptoms.

3. Control methods

Before sowing or transplanting rapeseed, apply an appropriate amount of borax; this can meet the rapeseed's demand for the element boron throughout the entire growth period. Generally, applying 1-2 jin of boron fertilizer per mu is enough; mix it into the base fertilizer and apply them together. At the seedling stage and the bolting stage, the foliar spraying method can be used to supplement the plant's boron needs; generally, spray a very low-concentration borax solution once each at the seedling stage, the bolting stage, and the flowering stage. When applying topdressing, apply nitrogen, phosphorus, and potassium fertilizers reasonably, and it is not advisable to apply any one of them exclusively, so as to increase the soil's boron content. Water promptly during drought, and drain promptly during the rainy season.

The above is an introduction to the symptoms of boron deficiency in rapeseed and the control methods. We hope it can help you. To learn more related knowledge, please stay tuned to us.