eChapters

The potential for significant economic losses from decay caused by postharvest pathogens is greater than is often realized. Harvesting and handling, and the attendant costs for labor and postharvest chemical treatments, can increase the cost of fresh fruits and vegetables several fold from the field to the consumer. Therefore, any produce lost in storage is worth more economically than an equivalent amount lost in the field. Considering economics and the problem of world hunger, it is imperative to understand the importance of postharvest disease and to continually strive to reduce postharvest losses from pathogens. In recent years, many international organizations have identified the necessity of reducing postharvest food losses as an important worldwide goal. While postharvest losses vary from season to season, an average loss of 10% to 30% after harvest is an average estimate. Significantly higher losses are not uncommon in developing countries. The extent of these losses justifies increased research efforts in postharvest pathology (Carl E. Sams, 1994). Chemical treatments and irradiation have effectively reduced the number of microorganisms on various commodities. However, consumer fears associated with chemical residues and the effects of ionizing radiation on fresh produce are forcing the development of alternative protection methods. Also, many pathogens have developed resistance to several commonly used chemicals, while other decaycausing microorganisms currently cannot be controlled by chemicals. Therefore it is better to seek control strategies that will supplement or replace current disease control methods.

Fruits, nuts and vegetables play a significant role in human nutrition, especially as sources of vitamins, minerals, dietary fibre, and antioxidants. Increased consumption of a variety of fruits and vegetables on a daily basis is highly recommended because of associated health benefits, which include reduced risk of some forms of cancer, heart disease, stroke, and other chronic diseases. Both quantitative and qualitative losses occur in horticultural commodities between harvest and consumption. Qualitative losses, such as loss in edibility, nutritional quality, caloric value, and consumer acceptability of fresh produce, are much more difficult to assess than are quantitative losses. Quality standards, consumer preferences and purchasing power vary greatly across countries and cultures and these differences influence marketability and the magnitude of postharvest losses. Postharvest losses vary greatly across commodity types, with production areas and the season of production. Losses of fresh fruits and vegetables in developed countries are estimated to range from 2 percent for potatoes to 23 percent for strawberries, with an overall average of 12 percent losses between production and consumption sites. In contrast, the range of produce losses in developing countries varies widely. Losses at the retail, food-service, and consumer levels are estimated at approximately 20 percent in developed countries and about 10 percent in developing countries (Adel A. Kader and Rosa S. Rolle, 2004 ). Overall, about one third of horticultural crops produced are never consumed by humans. Reduction of postharvest losses can increase food availability to the growing world population, decrease the area needed for production, and conserve natural resources. Strategies for loss prevention include use of genotypes that have longer postharvest-life, use of integrated crop management systems and good agricultural practices that result in good keeping quality of the commodity and use of proper postharvest handling practices in order to maintain the quality and safety of fresh produce.

1. INTRODUCTION

Fruits and Vegetables are heighly perishable crops and have to be handled carefully after harvest. Postharvest handling of these perishables is essential to prevent the post harvest losses and maintain the quality of the fruits and vegetables. Various treatments (chemical, physical and biological agents) have been standardised and used for retaining the storage quality of different horticultural commodities. All these aspects have been discussed in this chapter.

1. INTRODUCTION

In the changing global scenario, food nutrition, health care and livelihood security are the matter of great concern to human, social and economic development. Fruits and vegetables is one of the most important and fast growing sub-sectors as they form an indispensable part of healthy diet. The current trend shows that dietary habits are changing with increasing income, from cereal based diet to nutritious diet. Resultantly, there is a growing demand for horticultural produce.

World production of vegetables amounts to 1169.45 million tonnes, while that of fruits is 689.39 million tonnes (NHB, 2017). India is the second major producer of fruits and vegetables in the world and ranks next to China. India produces 92.85 million tonnes of fruits from an area of 6.5 million hectares and 175.00 millions tonns of vegetables from an area of 9.2 million hectares annually. The productivity of vegetables in India is 17.6 tonnes per hectare. Potato (28.9%), tomato (11.3%), onion (10.3%) and brinjal (8.1%) are the 4 major vegetables contributing 58.6% of total vegetable production in our country. Other important vegetables are cabbage (5.4%), cauliflower (4.6%), okra (3.9%) and peas (2.4%)

1. INTRODUCTION

India produces a large variety of fruits and vegetable due to varied agro-climatic conditions. These include mango, citrus, banana, apple grapes, strawberry, pineapple, litchi, guava, papaya, plum, peach, pear apricot etc. Astonishingly, it may appear but it is a fact that postharvest losses of fruits and vegetables in India are staggering. Infact the postharvest losses of fruits and vegetables are equivalent to the annual consumption of fruits and vegetables in U.K. In this article, a focus is made on the causes of postharvest losses of fruits, overview of various techniques used to prevent the postharvest losses constrains in postharvest technology and future strategies.

Postharvest food loss has been considered an unavoidable affliction since food storage first began. These losses are much more painful and costlier in terms of money and man-hours. Such losses due to plant parasitic nematodes, in particular, is severe in tropical regions especially in developing countries like India, where proper storage, transmit and marketing facilities are inadequate. In tropical agriculture, increase in production rate is generally low and, by itself, unable to keep pace with the requirements of the increasing population. Hence, such food shortage demands the need to reduce postharvest loss due to nematodes. Postharvest food losses also constitute a vast complex of physical and biological changes, which makes it very difficult to represent in a single figure. As suggested by different sources, an overall loss of at least 10 per cent occurs in the developing countries. However, the magnitude may range from negligible to cent percent in particular nematode species and crop.

In addition to causing direct losses individually, phytonematodes also favour the establishment of secondary, passive micro- organisms like fungi, bacteria, viruses etc. Nematodes cause mechanical wounds, which serve as avenue for the entry of secondary microorganisms (Ravichandra, 2008). This complex association results in severe damage to planting material.

Postharvest diseases due to nematodes can be managed through restricting the movement of infected planting material to uninfected areas; use of uninfected, healthy planting materials; use of treated planting materials; improvements in the cultural practices at the growing site; timely and careful harvesting; use of nematicides both at pre- and postharvest stages; employment of some physical means like heat, radiation etc; improved storage techniques and integration of these methods. By maintaining hygienic conditions during harvest, transportation, storage and packing most of the postharvest damage due to nematodes can be minimized. Of all the methods, however, regulatory measures like quarantine is more practical and effective in restricting the movement of nematode infected plant materials and contaminated soil into a state or country. Contaminated plant material should be treated (hot water or nematicides) to kill the plant parasitic nematodes before planting to prevent the further postharvest damage. These various measures are primarily aimed at either reduction or wiping out of stages of nematode from the site or protection of host from infection or creation of unfavorable host and/or environmental conditions for the nematodes.

Pomegranate is one of the oldest known edible fruits and is associated with ancient civilizations of the Middle East. From its origin in the area now occupied by Iran and Afghanistan, the pomegranate spread east to India and China and west to Mediterranean countries (Turkey, Egypt, Tunisia, Morocco, and Spain). Spanish missionaries brought the pomegranate to the Americas in the 1500s (Hodgson, 1917; LaRue, 1980). The primary commercial pomegranate growing regions of the world are the Near East, India and surrounding countries, and southern Europe. The fruit is consumed fresh or processed into juice, syrup, jams, or wine (Fig. 1) (LaRue, 1980; Adsule and Patil, 1995; Kumar, 1990; Patil and Karale, 2001; Roy and Wasker, 1997).

Potato, the third most important food crop in the world after rice and wheat is becoming the main source of food and income in developing countries. India stands second in production and area of potato in world after China leaving behind the Russian Federation. In India, potato is an important component in cereal and vegetable-based cropping systems for its ability to produce high dry matter/ha in short duration and high yield compared to cereals. It is grown as mixed crop, intercrop, relay or sequential crop along with other vegetables, cereals and cash crops.

Potato is originated in South America in the high Andean hills and towards the end of 16th century it was first introduced into Europe by Spanish conquerors. In the early 17th century, it was brought to India by British missionaries or Portuguese traders. Thus, potato developed as a temperate crop and was later distributed throughout the world. Cultivated potato consists of two sub species, Solanum tuberosm ssp. andigena and S. tuberosum ssp tuberosum. Subspecies andigena is the primitive form which is adapted to shorter day length and high altitudes of mountains (above 2000). The presently cultivating tuberosum subspecies is adapted to long or short day condition of tropical regions and lower altitudes (500-200m above MSL) and is believed to be evolved from andigena types through selection.

Morphology and Floral Biology

Potato is herbaceous in nature with erect to prostrate stem. Stem is variably coloured from green, purple or mottled green or purple. Leaves are pinnate which ends in single terminal leaflet. Stolon arise from the portion of the plant below the ground. The stolon bears rudimentary leaves and tip is hook shaped. The sub apical portion at the tip of stolon enlarges to produce tubers. Hence, potato tubers are the modification of underground stem with shortened axis and poorly developed eyes. The leaf scar with a subtended lateral bud having underdeveloped internodes is referred to as the eye of the tuber. Potato is a long day plant. Moderate humidity and long day condition favours flowering. Hence flowering and fruit set is observed in hilly tracts. Inflorescence is produced terminally and is usually cymose. Flowers are bisexual, actinomorphic, and hypogynous with 5 calyx, 5 corolla and 5 stamens. The colour of corolla varies from white, pink, lilac, blue and purple. Pollen shedding is through the pores at the tip of the anthers. Mature fruit is a berry. Self-incompatibility is observed in diploid species and tetraploids are self-compatible.

Potato has special seed production problems as the quality characteristics of seed potatoes are influenced by a number of factors and important amongst them are the diseases and pests namely, viruses, fungi, bacteria and nematodes. Once the seed tuber is infected the pathogens, specially viruses, permeate through the plant system. The plant growth, therefore declines and the yield reduces progressively. It is therefore, important that seed stocks should not only be genetically pure but also should be in right physiological condition and disease free at the time of planting. Seed production technology developed for seed potato production, thus aims at producing disease free, genetically pure seed. There are now two independent channels of seed production for hills and plains.

Hill seed : The seed produced in hills (2500 metres above sea level) at suitable locations is called ‘Hill Seed’.

Plain seed : The seed produced in plains at suitable locations is called ‘plain seed’. Northern plains have emerged as an important source of potato seed production. The low aphid, plains seed is in right physiological condition at the planting time and yields higher than the traditional hill grown seed.

Once healthy seed potatoes are introduced into the system of growing them during low Aphid period accompanied by a systematic insecticide application, roguing and removal of haulms before the aphids attain critical number and the re growth is checked, the health standards for the seed crop could be maintained for a number of generations. This system of seed potato production has been designated as ‘Seed Plot Technique’.

INTRODUCTION

Potato (Solanum tuberosum L.) is 3^rd most important noncereal food crop in the world, after rice and wheat, and popularly known as ‘the king of vegetables’. Potatoes are considered as a nonfattening, nutritious and wholesome food, which supply important nutrients to the human diet. Tubers contain significant concentrations of vitamin C and essential amino acids. Potatoes can be consumed in many ways, including baking, boiling, roasting, frying, steaming, and microwaving. It is integral part of food and traditional cousins and likely to find more importance in the dietary habit. Potatoes are either consumed directly or they are processed to give products such as chips and French fries, mashed and canned potatoes. Besides being important in human diet, potatoes are also used as animal feed and as raw material for starch and alcohol production. Potato was an occasional dish of the affluent class at the time of independence but now it is the most abundantly consumed horticulture based food by the poorest of the poor in the country. At present about 68% are utilized for table purpose, 7.5% for processing; 8.5% for seed and remaining 16% produce goes waste due to pre and postharvest handling.

1. Early Blight
Diagnostic Symptoms
• Brown-black necrotic spot-angular, oval shape characterized by concentric rings .
• The concentric ring produce a target board effect, the most characteristic symptom of the disease.
• Several spot coalesce & spread all over the leaf.
• In severe attacks leaves shrivel and fall down.
• Infection and rotting of tubers has also been reported (Fig.1).
Etiology
Scientific Classification
Kingdom : Fungi
Phylum : Ascomycota

Introduction

At the time of inception of CPRI, in the year 1949, India used to produce 1.54 million tonnes potatoes from 0.234 million ha area at an average productivity level of 6.58 tonne/ ha. As per the first advance estimate of the NHB, the potato production in India during 2018-19 was 52.5 million tonnes from 2.18 million ha area at 24 tonnes/ ha productivity. The potato production, area and productivity increased over 7 decades by 34, 9.3 and 3.7 times, respectively. ICAR-CPRI has been adequately recognised by the nation on several occasions for this stupendous contribution. However, potato in India still has to transform from simply a vegetable supplement to serious food security option. Ability of potato to produce highest nutrition and dry matter on per unit area and time basis, among major food crops, made FAO to declare it the crop to address future global food security and poverty alleviation during 2008. Rising number of working couples, rapid rate of urbanization, enhanced tendency of eating out of home, higher disposable income levels of people and important place of potato in fast food items, create an ideal situation for expansion of potato consumption in the near and distant future.

A perusal of various R&D efforts and outcomes in the field of agriculture in general and, more specifically the potato, reveals that “Business as Usual” scenario would not hold much longer. We have to anticipate and get ready to tackle much more complex and diverse future challenges in our respective fields. As the time lag between research and development efforts and the final application/ adoption of the output may stretch over decades, a long term vision and blueprint of action plan is highly important. This chapter attempts to envisage long term state of affairs of potato industry in India and formulate a strategy to fulfil national needs through a well-documented plan to tackle anticipated challenges.

INTRODUCTION

Potato is an important horticultural food crop which has the potential to meet food demand of the fast growing human population across the world, including India. This is going to be the future food crop for the millions especially in the third world countries. However, this crop is highly prone to wide range of diseases and pests that are considered to be the main bottle neck in potato production across the globe. Amongst the biotic stresses, late blight caused by oomycete Phytophthora infestans (Mont.) de Bary has historically been an important disease of potatoes and tomatoes worldwide. In the mid 1800, late blight caused widespread crop failures throughout Northern Europe including Ireland where it was responsible for the Irish famine. Since then, it has spread far and wide and now occurs wherever potatoes are grown. Losses due to P. infestans have been estimated to € 12 billion per annum of which the losses in developing countries have been estimated around € 10 billion per annum (Haverkort et al., 2009). In India, average annual losses to the tune of 15% have been estimated which amounts to 7.95 million tons of potatoes (Current production is 53 MT). Disease appears every year in epiphytotic form in hilly regions whereas in the plains, although it usually appears every year but its intensity is low (traces to 25%). It is only in few years that it assumes epiphytotic form leading to crop losses to the tune of 40%. Recently, late blight has become a serious problem in kharif grown potatoes and tomatoes in Karnataka state (Sharma et al., 2015). Phytophthora infestans is considered as re-emerging pathogen due to regular emergence of its novel strains with increased virulence and its appearance in new locations with surprising intensity. Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars.

INTRODUCTION

Potato is a highly versatile crop grown in varying environmental conditions viz. plains, hills and plateau in India. It is grown under short days (SD) in the plains in autumn season and under long days (LD) during summers in hills. Therefore, the pattern of growth, duration of crop as well as the yield varies according to the environment. Besides, the potato cultivars differ from each other in relation to their morphological characters, response to the environmental factors and finally in yield and the dry matter accumulation. The biochemical reasons for such variations are not clear, but it seems that genetically determined differences in the synthesis of growth regulators such as auxins, cytokinins, gibberellic acid (GA) and abscissic acid (ABA) play an important role and their proportion at different growth stages affect the growth and development and thus, the yield of the cultivar (Minhas and Singh, 2003).The present chapter deals with the physiologicalfactors, which determine the growth, development and yield of potato crop.

INTRODUCTION

Potato production in India has shown a steady increase in the past, presently making the country second largest potato producer in the world. As per the latest available data, during 2018-19, approximately 52.5 million metric tons of potatoes have been produced (NHB, 2019). Increase in production, often resulting in gluts at harvest, has led to several post-harvest problems like storage and proper utilization of the produce. About 90% of the potato crop in the countryis harvested during January-February in the Indo-Gangetic plains comprising the states of Punjab, Haryana, UP, Bihar, West Bengal, MP and Gujarat where the harvest is followed by rising temperatures of hot and dry summer, and further by warm and humid rainy season. Since potato tubers contain about 80% water, under such circumstances, a semi-perishable commodity like potato, cannot be stored for more than 3-4 months without refrigeration because of very high losses due to shrinkage, sprouting and attack by microorganisms.

Therefore, potatoes are mostly stored in refrigerated cold stores maintained between 2-4^oC and 90-95% relative humidity (RH). Low temperature storage has advantages of natural control of sprout growth, low evaporative losses and minimum risk of diseases and pests. These conditions are ideal for storage of seed potato but these cause cold-induced sweetening leading to excessive accumulation of sugars in most of the potato cultivars making them unfit for processing due to browning in chips. Also, such tubers are less preferred for consumption because of sweet taste. Hence, potatoes meant for processing are either stored under non-refrigerated conditions for short term or stored at 10-12^oC with the use of some sprout suppressant like CIPC (isopropyl N-(3chlorophenyl) carbamate) to minimize the accumulation of reducing sugars. The chips produced from such tubers are light in colour.

Potato processing on the other hand is essential to sustain the increasing potato production in the country and to provide proper remuneration to the cultivators. Potatoes can be processed into a variety of products. Potato chips, French fries and dehydrated chips are the most popular processed potato products in the organized and unorganized sectors. The present chapter deals with postharvest management of potatoes in terms of dormancy and sprouting issues and storage technologies for seed, table and processing potatoes. Besides, areas suitable for growing processing potatoes in the country, potato processing scenario in the organized and unorganized sectors are also discussed.

INTRODUCTION

India is the second largest producer of potato in the world contributing about 12.52%of production from 11.29 % area under potato with an average yield of 22.31 t/ha. Potato is grown in almost allthe states in India under diverse agroclimatic conditions. About 90% of the total potato area is located in the subtropical plains, 6% in the hills and 4% in the plateau region of the peninsular India. Indo-Gangetic plains account for about 76% of the potato area and about 87% of the potato production in the country. Availabilityof assured qualityseed is the most important production constraint in all the potato growing regions of the country.

Seed is the basic vital input in agriculture and its timely availability in adequate quantity as per demand decides the strength growth of agricultural economy in the country. Seed has played a very important role in India’s green revolution and shallcontinue to be the importantcomponent in the days to come. There is a saying “as you sow, so shall you reap”, which traditionally relates to the quality of seed determining the production, has been the wisdom of our forefathers. The traditional farmers’ practices are to save their own seeds generally selected from healthy plants from fields which are freefrom diseases pests, harvest them separately, clean, cure and then store in containers and inspect regularly for any kind of damage; or they get quality seed from other seed producing farmers onbarter basis, indicating thereby the importance of seed in their production system.

INTRODUCTION

Potato (Solanum tuberosum L.) is the most importantnon-grain food crop of the world and is central to global food security, offeringhigher yields in calories per acre thanany grain.More than 2 billion people worldwide are estimated to be dependent on potato for food, feed or income. Global potato breeding concentrates on the objectives of increasing the yields through resistance to various biotic and abiotic stresses along with improving quality traits but the cultivated potato is an auto-tetraploid (2n=4x=48), clonally propagated, highly heterozygous, and suffers acute inbreeding depression. All these characters complicate genetics/genomic studies as well as breeding efforts to improve important traits such as disease/pest resistance, processing quality and nutritive value.This has lead to the need of high quality, well annotated genome sequence of potato along with high resolution mapsfor aiding the identification of allelic variants for important agronomic traits in potato. Multiple linkage maps have beenconstructedfor potato usingvarious molecularmarkers like RFLPs, AFLPs and SSRs in an effort to develop markers for marker assisted breeding and facilitate map based cloning. These earlierefforts got unequivocal boost when an internationalcollaborationof13countriesviz.Argentina, Brazil,China, Chile, India, Ireland, The Netherlands,New Zealand, Peru, Poland, Russia, the United Kingdom and the United States came together to form the Potato Genome Sequencing Consortium (PGSC) with aim to decipher the potato genome (Xu et al., 2011). The potato genome sequence has provided a major boost to gaining a better understanding of potato trait biology, underpinning future breeding efforts. This would greatly help in enhancing the breeding techniques by implementing the genome assisted methods for imparting the greatertolerance to various biotic and abiotic stressesand ultimately increasing the yields. The knowledge of the complete genome sequence is an invaluable resource for the identificationof genes and variant/novel alleles of genes for everytrait ofinterest to potato breeders. This is very much required for feeding the ever burgeoning global population.

Introduction Potato, scientifically known as Solanum tuberosum, is a starchy tuberous crop that belongs to the nightshade family, Solanaceae. It is one of the most widely consumed and important food crops worldwide. Potatoes are native to the Andes region of South America and have been cultivated for thousands of years. They have since become a staple food in many countries and have significant cultural and economic importance. Potatoes are known for their versatility, as they can be prepared and cooked in various ways. They are typically harvested from underground stems called tubers, which come in a variety of shapes, sizes, and colours. The most common varieties have brown or yellowish skin and white, yellow, or creamy flesh. However, there are also red, purple, and even blueskinned potatoes available. The cultivation of potatoes is widespread, with major potato-producing countries including China, India, Russia, the United States, and Germany. Potatoes are adaptable to different climates and can be grown in diverse environments. They are an important crop for food security and economic stability in many regions. Beyond their culinary significance, potatoes have also contributed to scientific advancements.

Aphids: Myzus persicae, Lipaphis erysimi and Brevicoryne brassicae Aphididae
 
Aphids suck the sap from potato foliage, causing wrinkling, cupping and downward curling of young leaves. The older leaves will become yellow, wilt and fall off.  They also excrete honeydew on which sooty mould develops covering affected parts with a thin superficial black coating that hinders photosynthetic activity of leaves resulting in stunted growth of plants. In addition, they also act as vectors, for transmitting potato leaf roll virus. Major damage by M.persicae and A. gossypii is through transmission of potato leaf roll virus.

Potato is fourth major food crop after rice, wheat and maize in the world. It produces the highest dry matter, well balanced protein and more calories/ unit area and time. Unlike other food crops, potato tubers contain vitamin-C (17 mg/100 g). It provides carbohydrates, minerals, fibre and a number of vitamin-B groups. Potato protein is comparable to that of milk and egg. Unlike European countries, in tropics and sub-tropics, the crop is of short duration and fits well in intensive cropping system. It can be grown in a wide range of climatic and soil conditions and tubers are available throughout the year. Tubers can be left un-harvested in the soil for some time and are also suitable for long distance transport and storage. Several products like chips, flakes, French-fries, finger chips, granule, disc, cubes and flour are made out of potato tubers

Origin and distribution

Potato is a native of tropical South America. Traditionally, it was adapted as a commercial food crop in temperate climate under long day conditions, mainly in Europe. It was introduced to India in 16^th or 17^th Century by Portuguese or the British.