Boron and its importance in fruit crops

 Boron (B) was recognized as an essential plant nutrient by Warington in 1923. The deficiency of B in fruit crops is the second most extensive micronutrient deficiency. More than 90% of the B in plants is associated with cell walls, and its most important role is connected with cell wall development, functioning and strength. It is important in the production and quality of fruits because it plays an important function in different physiological processes within plants. Species differ widely in their B requirements, being it higher for dicots than monocots because of the higher B concentration in their cell wall. B requirement is much higher for reproductive growth than for vegetative growth in most plant species because reproductive organs have a high concentration of pectin which is rich in B. It is crucial to note that, while boron is necessary for fruit crop growth, too much of it can be hazardous. A balanced and well-calibrated strategy for fertilization, like all nutrients, is critical to ensure maximum development, production, and fruit quality in fruit crops. Boron application rates for specific fruit crop kinds and growth conditions can be determined through regular soil testing and consultation with agricultural professionals.

Functions of boron in fruit crops

Pollen tube formation and fruit set: Boron is engaged in pollination and contributes to the formation of pollen tubes. Boron levels that are adequate promote appropriate pollination and fertilization, resulting in improved fruit sets and a greater quantity of healthy fruits.

Cell wall formation: Boron is required for the creation and stabilization of plant cell walls. It stimulates the cross-linking of pectin, a component of the cell wall that gives plant cells strength and stiffness. This is especially significant in fruit harvests since it helps to retain fruit firmness and texture.

Flower and fruit development: Boron has an impact on flower and fruit growth. It is especially critical during the early phases of fruit growth. Boron deficit can result in irregular fruit shape or fruit drop, whereas enough boron levels can contribute to uniform and healthy fruit development.

Carbohydrate metabolism: Boron is required for normal carbohydrate metabolism in plants. It facilitates in the translocation of sugars from leaves to growing fruits, promoting development and sugar buildup, which influences the taste and sweetness of the fruit.

Nutrient uptake and utilization: Boron aids in the intake and utilization of other vital nutrients such as calcium, potassium, and magnesium. It aids in the maintenance of a good nutrient balance inside the plant, which is critical for overall plant health and fruit quality.

Seed and fruit production: Boron influences the formation and development of seeds within the fruit. Healthy seeds are critical for the proliferation of fruit crops, and boron shortage can result in lower seed yield and poor seed quality.

Stress resistance: Boron helps plants endure environmental challenges such as drought, heat, and infections. Fruit crops with proper boron levels are better able to tolerate harsh conditions, resulting in higher yields.

Boron deficiency symptoms in plants

Root growth impairment: Boron deficiency can decrease root elongation and overall root growth. This restriction limits the plant's ability to absorb water and nutrients from the soil.

Stunt growth: Affected plants may grow slowly (stunt growth), with shortened internodes and reduced leaves.

Yellowing of new leaves Boron deficiency frequently causes yellowing of the plant's young leaves near the developing tips. This is known as inter-veinal chlorosis, and it occurs when the tissue between the leaf veins turns yellow while the veins stay green.

Death of growing tips: The plant's growing tips, such as the shoot and root apices, can die back, resulting in diminished or interrupted growth.

Abnormal flower and fruit: Boron is required for the development of flowers, pollination, and fruit formation. Deficient plants may produce malformed or tiny flowers, as well as odd fruits.

Brittle and cracked stems and petioles: Boron-deficient plant’s stems and petioles can become weak and brittle, cracking or breaking under stress.

Boron deficiency disorders in fruit crops

• Corky cork or internal cork in apple
• Black measles in apple
• Hard fruits in citrus
• Black tip of mango
• Fruit cracking of pomegranate
• Snake heart in walnut
• Die back and fruit cracking in apple
• Internal necrosis of mango and aonla
• Hen and cheken diseases in grapes

Causes of boron deficiency

Boron-deficient soil: Some soils have naturally low boron levels, making it difficult for plants to receive enough amounts of this critical nutrient.

Soil pH imbalance: Too acidic or alkaline soil pH levels might influence plant boron availability. Boron may become bonded and unavailable to plants in acidic soils, whereas boron may become too soluble and susceptible to leaching in alkaline soils.

Excessive irrigation or rainfall: Boron can leak from the soil in areas with high rainfall or irrigation, resulting in plant shortages.

Sandy soils: Sandy soils are more susceptible to boron leaching than clay soils, raising the danger of boron deficiency in plants growing in these conditions.

High organic matter content: Soils with a high organic matter content can bind boron, decreasing its availability to plants.

Plants with limited boron mobility: Some plants have poor capacities to transfer boron within their tissues, making them more susceptible to shortage.

Management of boron deficiency

Soil Testing: Perform a soil test to examine boron levels in the soil and determine if there is a deficiency.

Fertilizer application: Treat the soil with boron-containing fertilizers if boron deficiency is proven. Borax and other boron-containing chemicals can be used as fertilizers to compensate for the deficiency.

Foliar sprays: In severe circumstances, boron foliar sprays can be recommended for the leaves to provide an immediate cure.

Soil pH modification: Ascertain that the soil pH is in the ideal range for boron availability (often slightly acidic to neutral).

Soil mulching: Mulching can assist prevent boron leaching in sandy soils while also retaining moisture, which may benefit boron uptake.

Boron deficiency indicator plant (Sunflower)

Sunflower basically displays boron deficiency symptoms, and because it is easily produced under poly-house conditions. If it does not exhibit boron deficiency signs within a short period of time, it is safe to assume that adequate boron is being supplied for normal growth. If it exhibits symptoms, other plants' reactions should be investigated. Sunflower symptoms include terminal bud growth arrest, reduced dry weight, and aberrant leaf features. For boron deficiency symptoms to appear fast, enough levels of other essential nutrients must be present.