Boron Deficiency in Durian
Boron is an essential micronutrient for plants, including durian trees. As with other fruits, boron impacts growth and quality of the durian fruit. For example, boron positively interacts with sulfur which can help improve soil fertility and increase durian yield. Research by Mitali Mandal et al (2018), showed the interaction effect between boron and sulfur might be helpful in maintaining boron and sulfur in soil vis-a-vis in moderating some important biological indices in a most favorable state, which ultimately improved soil fertility with simultaneous increase in yield. Durian is a chloride sensitive crop and normally farmers apply sulfate of potash for potassium input. Good sulfur content in the soil enhances the production of volatile sulfur compounds in durian. This contributes to the distinct smell and taste of durian fruit.
Boron deficiency can have significant impacts on durian trees, affecting their growth, development, and fruit production. Signs and symptoms of boron deficiency in durian include:
- Poor flowering and fruit set: Boron deficiency hampers the development and functionality of reproductive organs, leading to poor pollination and fertilization.
- Abnormal fruit development: Fruit may be small, misshapen, or have uneven growth.
- Cracked or split fruits: This occurs because boron plays a role in cell wall formation and elasticity. Without sufficient boron, the fruit's skin may not be able to expand properly, resulting in these types of defects.
- Corky tissue: Durian fruit tissue appears dry, cork-like, and can negatively affect the fruit's texture and quality.
- Leaf symptoms: Durian tree leaves may exhibit chlorosis, yellowing along the edges, and eventually necrosis or death of leaf tissue. The affected leaves may also become brittle or show signs of deformation.
When boron deficiency happens in durian it can also result uneven fruit ripening (UFR) which is characterized by:
- Hardened, leathery aril
- Whitish color
- Odorless and tasteless pulp
UFR normally occurs when the fruits are about to ripen and remains invisible until the fruits are opened. D159 Monthong, D197 Musang King, and D24 varieties that have bigger pulp flesh will face a higher chance of UFR.
In addition to preventing UFR, boron encourages flower bud initiation as well as increases flower production and retention—all of which can increase fruit yield. Boron also plays a vital role in pollen tube elongation, and seed and fruit development. Boron deficiency can cause incomplete pollination.
Unfortunately, boron deficiency symptoms often reveal themselves once fruit yield has decreased. U.S. Borax recommends regular soil and tissue testing to ensure you are giving your trees an adequate supply of boron throughout their growing cycle.