Visual Quality Defects in Citrus Fruits: Reducing Farmer’s Profit
Citrus is one of the most important fruit crops grown in more than 50 countries of the world. All citrus fruits are member of “Rutaceae” family and characterized by juicy vesicles packed inside the segments within fruit. Segments usually adhere with each other and covered by a spongy white layer called albedo.
Number of segments vary with cultivar and size of fruit. China is leading producer of citrus fruits followed by Brazil and India. Famous citrus fruits grown in world are oranges (contribute 47% of total citrus production), mandarins, tangerines, grapefruit, pummelo, lemons, limes and many hybrids. They are famous for their nutritional and economic benefits.
Nutritionally, citrus fruits are rich sources of vitamin C, soluble fiber, folate and antioxidants. They also contain significant amounts of minerals like potassium, phosphorus, calcium, iron and zinc.
Citrus Fruit Quality
Citrus fruit quality is very important for consumer acceptance and market value. Fruit quality in citrus is divided into two categories, i.e. visual or external fruit quality and internal fruit quality. Visual quality attributes are fruit size, shape and color.
Additionally, consumers prefer citrus fruit which is free from physical injuries, scars, spots, blemishes and signs of disease or insect damage. These attributes of fruit are linked with visual quality of citrus which determines the market value and consumer preference.
Customers pay higher prices for fruits having uniform and proper coloration, normal size and shape and free from above-mentioned damages. On the other hand, fruit taste, sweetness, flavor, proper combination of sugars and acids along with nutritional value are internal fruit quality traits.
These are also linked to consumer acceptance and market value. However, visual quality is the first preferable indicator for determining price, marketability and consumer preference.
Visual Quality Defects in Citrus
Visual defects in citrus fruit significantly reduce overall look and quality of fruit leading to higher rejection from consumers. Resultantly, fruit with visual defects sales on lower prices and reduces farmers’ profitability. Different biotic, abiotic and managerial factors influence fruit quality and become the cause of visual quality defects in citrus. Major visual quality defects of citrus fruits are described here in detail:
1. Fruit size
Fruit size plays important role in fruit selection by the buyers. Bigger fruits fetch higher prices in the market when compared with smaller fruits. Although every cultivar has different fruit sizes, it is also influenced by natural stresses and orchard management practices.
Deficiency of both macro and micronutrients like nitrogen, potassium, iron and zinc reduces fruit size and yield. Similarly, severe attacks of sucking insects also contribute to reducing fruit size in citrus. Moreover, irrigation or drought stress significantly reduces fruit size. By managing these factors, uniform and proper fruit size can be attained for higher market prices.
2. Fruit shape
Fruit shape is also visual quality parameter. Normal fruit shape is essential for marketing. Defects in fruit shape are less common, but their presence completely destroy fruit quality and marketability. Misshaped fruits may completely fail in marketing and not be accepted by the consumers.
Citrus greening disease which is commonly known as HLB is cause of misshaped fruits. It not only causes shape defect but also reduces fruit size and color development. HLB infected fruits have poor visual quality and significantly reduce farmers profit due to less selling price.
3. Fruit color
Fruit color is one of the most significant quality attributes for determining consumer acceptability. Fruit color in citrus is influenced by multiple natural and managerial factors. First of all, proper maturity and ripening are essential for color development in citrus. Fruit must be harvested after proper ripening for better coloration.
Proper sunlight is essential for conversation of green color to yellow, orange-yellow, orange and orange-reddish coloration of different citrus cultivars. For instance, lemons show yellow color after ripening while majority of oranges and mandarins have orange to orange-reddish color.
Plant must be properly pruned for penetration of sunlight which helps in better color development of citrus fruits. Nitrogen deficiency, attack of viruses and HLB diseases cause poor color development in citrus fruits.
These factors must be managed to improve fruit color. Use of plastic or reflective mulching is helpful for increasing coloration in citrus. Similarly, foliar application of magnesium and canopy management are also helpful for increasing peel color in citrus.
4. Skin blemishes
There are different types of blemishes including physical injuries, insect damage, disease attacks and damage of poor handling during harvest, transport and storage. All blemishes destroy the visual quality of citrus and thus contribute to reducing profitability of farmers.
In fields, blemishes are caused by wind injury, sunburn, attack of diseases like citrus canker, scab, melanose and HLB, insects like mites, thrips and peel miners. These blemishes can be minimized by improving management practices like pruning, utilization of proper nutrients and insect and diseases management.
Moreover, poor harvesting techniques, tools and improper handling during transport and storage also cause blemishes. Harvesting must be done properly with clippers to avoid physical injuries and visual blemished during harvesting. Similarly, handling with and use of proper packaging material is helpful for reducing blemishes during postharvest management.
5. Disorders
Different physiological disorders like Oleocellosis, Creasing and fruit splitting also contribute to visual quality defects to reducing fruit quality. These disorders are caused by environmental factors and poor orchard management practices. For example, deficiency of calcium increases chances of creasing and fruit splitting.
Hence, by improving management practices we can minimize the disorders contributing to visual quality in citrus. Application of plant growth regulators (PGRs) like GA3, NAA and 2,4-D are helpful for controlling these disorders and improving visual quality of citrus.
6. Insect damage
Some insects directly damage fruit skin to reduce fruit quality. Mites and thrips directly feed on fruit skin and left scars on fruit skin which become more prominent with the passage of time as fruit grows in size.
Fruit fly may cause decaying and rotting of citrus after laying eggs inside the fruit. Control of these insects is essential for minimizing visual defects in citrus. These insects can be controlled by improving sanitation in orchards and by spraying proper insecticides.
7. Disease damages
Attacks of different diseases like citrus canker, melanose, fruit rot and citrus scab not only reduce fruit size and color development but also produce different spots and blemishes on fruit surface. For example, canker produces brown corky spots on fruit which completely destroy visual quality of fruits.
Citrus scab and melanose produce scars and blemishes on fruit skin while fruit rot cause decay of fruit to reduce visual quality. Fruits infected with these diseases show poor visual quality and thus fetch less price in the market. Severe attacked fruits may be completely rejected by the consumers in fresh fruit markets.
Hence, by improving sanitation of orchards, management practices and spraying proper pesticides for control of these diseases we can reduce disease attack. Management of these diseases is essential for protecting fruit from visual quality defects.
Conclusion
Visual quality is very important in citrus fruits cultivation for fetching maximum price and earning sustainable profits. Visual quality defects must be minimized through better management and control of pests and diseases. Farmers must focus on producing citrus fruits with better visual quality. Increasing only fruit production is not sufficient for sustainable profits as fruit with poor visual quality does not fetch better prices and may cause losses to farmers due to higher consumer rejection.
Consumers pay extra price for fruit free from damage and have excellent visual look. Thus, visual defects in citrus fruits reduce overall look and quality of fruit leading to low prices in market and loss of profits for farmers. Farmers must take care of visual quality of citrus fruits along with higher production to earn better and sustainable profits.
