(Junaid Ul Hasan, M. Modassar Ali, M. Yousaf Quddoos)
(Institute of Food Science and Nutrition, University of Sargodha)
Pakistan is known worldwide for some fruits, citrus is one of the most important to be counted. Pakistan is a place where high-value citrus is produced and is exported to a number of countries. The citrus produced in Pakistan is well known and demanded in the international market. Among the horticulture crops, citrus is most famous in Pakistan. A significant increase in the production was observed from 2001-2010. Pakistan is ranked at 10st in the list of citrus producing countries in terms of area and production. The demand of citrus either fresh or processed is increasing day by day among the consumers. In a report by FAO, the largest producer of Citrus is Brazil followed by China then the United States. In Pakistan the most of citrus is cultivated in the Punjab, because of the suitable temperature and climatic conditions. Citrus is a genus of flowering trees and shrub in the family rue. Includes many varieties i.e. kinnow, mandarins, grapefruits, pomelos, lime, lemons, blood orange, bitter orange, calamondin, citron, key lime, and kumquat. It has high nutritional value and contains phytochemicals of great importance. Phytochemical include carotenoids (beta-carotene, lutein, beta-cryptoxanthin), and flavonoids. Vitamins includes vitamin c, thiamine, riboflavin, niacin, folate, pantothenic acid and others. Minerals includes calcium, iron, magnesium, manganese, phosphorous, potassium and zinc. It was firstly developed by H. B. Frost in citrus research center California. Citrus is grown in tropical to subtropical climates. According to a survey in 2015-16 total citrus production of Pakistan is 2.36 million tons on an area of 206,569 hectares. Kinnow is the largest fruit containing 12 to 25 seeds per fruit and has globular shape. Seeds are major problem in out of hand eating so seedless (triploid) varieties had also been developed. Naturally seeds are diploid or tetraploid. Seed has two parts seed coat and embryo. There is a small hole in the seed coat through which pollen tube passes and radical emerges. Embryo has three parts radical plumule and cotyledons. Roots are present at the bottom end and their function is to absorb nutrients and also to anchor the plant with soil. Best soil for citrus has pH from 6.0 – 7.0. Basically, taproot system is present. Citrus has evergreen leaves with the life of almost three years. Citrus consists of single fleshy fruit. Exocarp is called flavedo and mesocarp is called albedo. The endocarp contains juice vesicles and is the edible part of fruit. It has high demand over all the world due to its special flavor, odor, juice content and vitamin c. Some important export markets for kinnow are: Bahrain, Dubai, Kuwait, Oman, Qatar, Saudi Arabia, Indonesia, Malaysia, Afghanistan, Netherlands, Philippines, Singapore, the United Kingdom and Vietnam. Harvesting of citrus is done during December to February when outer color of fruit becomes orange. Best time is mid-January to mid-February (TSS 12:1 to 14:1). Harvested by sharp clipper called as secateurs from the stem. Stem is removed as early as possible because it can cause damage to other fruits when packed. It is a loose peel fruit so harvesting by direct pulling is avoided as it can cause harm to fruit. Processing of citrus includes following steps starting from the orchard. First step is picking (with the help of manual clippers), transportation to processing plant, washing and drying (in order to remove dirt and dust), waxing(in order to prevent water loss), drying (for wax stability), grading and sorting (basically a quality parameter and done on the basis of color and size), packing, weighing, chilled storage (at least 72 hrs. is mandatory or recommended under the temperature of 2ᵒc to 4ᵒc to increase the shelf life of kinnow or to sustain the quality of kinnow for a stipulated period), shipment port, shipping, and at last delivered to international market. Quality and standard includes the parameters like juice content, shiny surface, and blemish free and insect free fruit. Other includes gap certifications, skilled labor, blast chillers and controlled atmosphere rooms. Farm management has also an important role in determining citrus quality. There are a lot of problems related to citrus, diseases are one of them. Some important bacterial diseases of citrus are citrus variegated chlorosis, citrus canker and black pit. Fungal diseases include albinism, Alternaria brown spot, Alternaria stem-end rot and anthracnose, black mold, blue mold, black rot, branch knot, charcoal root rot, damping off and fusarium rot. Viral diseases includes citrus mosaic, bud union crease, citrus yellow mosaic, navel infectious mottling, psorosis and satsuma dwarf. These diseases either bacterial or fungal effect the quality of citrus badly. The market of citrus also falls by these. Pest attack is also a major problem. Tylenchulussemipenetrans Cobb. And other nematode species are associated with the rhizosphere of diseased plants. One of the most dangerous disease Citrus cancer is bacterial basis caused by Xanthomonas Pv. Citri. Colletotrichumgloeosporioides Penz. causes citrus whiter. In spite of these, there are attacks of pests during storage and maybe during transportation. Several measures should be taken to avoid any kind of past attack either in the field or in storage or transportation.  Now comes the problems related to citrus processing. Alternate bearing phenomenon means low yield in alternate year, there is lack of competitiveness in citrus industry which makes it underdeveloped, there is poor management practices during handling, transportation , storage and shipment of fruit, citrus of Pakistan has higher demand but higher number of seeds is a major problem, long growing period of kinnow and late maturation, growers purchase poor quality seeds from unspecified nurseries which results in lower yield, lack of R&D facilities and internationally accredited laboratories is one of the major cause, Pakistan citrus processing industry is labor dependent and facing shortage of skilled labors, attacks of various diseases, imbalanced fertilization and load shedding are some important constraints. In Pakistan citrus industry is facing many pre-harvest and post-harvest problems. These problems greatly affect the citrus quality and its exports. This ultimately results in economic loss to the economy of the country and also to the farmer. These problems include lack of education, poor organization of the institutions, undeveloped citrus industry, lack of management during sewing, growing, harvesting, storage and transportation and packaging.  The problems from citrus growing, its development, harvesting, transportation and storage lead to the poor quality of citrus. Summing up, Citrus is an important Horticulture product in Pakistan, it shares an important part in raising the economy of Pakistan and the citrus of Pakistan is known all over the world by its name. It is highly nutritious and readily available. Citrus processing industry is being raised in Pakistan and fighting with the major problems related to its processing, transportation and storage. There are several diseases that lead to poor quality of citrus. Pest attack is also a major problem in reducing the quality of citrus. Finally, measures should be taken to control diseases and improve the quality of citrus.
