eChapters

Powdery Mildew

Erysiphe polygoni

Diagnostic Symptoms

• At first symptom appears on leaves.

• White floury patches appear on both surface of leaves as well as tendrils, stem and pod.

Wilt

Fusarium oxysporum f.sp. vasinfectum

Diagnostic Symptoms

• Disease affects the crop at all stages.

Diagnostic Symptoms

• Symptoms can occur at both the seedling and plant developmental stages and appear as patches in the field

• It usually occurs near or at the reproductive stages (flowering to podfilling) of crop growth

Diagnostic Symptoms

• At first pale-green chlorosis, typically appear on lower leaves and extending up the plant.Leaves eventually take on a dull-yellow colour, wilt and the plant collapses and dies.

Diagnostic Symptoms

• Intially chlorotic (yellowed) lesions and sometimes galls appeared on the upper leaf surface.

• There are corresponding white blister-like dispersal pustules of sporangia on the underside of the leaf.

Diagnostic Symptom

• Circular to oval, dark brown to black spots appear on the leaves.The spots enlarge into round to irregular spots with concentric rings and coalesce causing blighting and withering of leaves.

• These are surrounded by chlorotic zone with grey white necrotic center.

Diagnostic Symptoms

• Practically all above ground parts are affected, but stalks are the main targets of stack.

• Spindle leaves (third or fourth) starts drying.

• Further stalks becomes discolored and hollow.

Rust

The rust of wheat has been studied more than any other disease in the world. In India, K.C Mehta and his associates studied this disease with exemplary zeal. Three rusts of wheat are known. These are Black stem rust, caused by Puccinia graminis tritici, Brown rust (leaf rust), caused by Puccinia recondita, and Yellow rust, caused by P? striiformis. Brown and yellow rusts cause more damage thant the black rust, because of early appearance in the season.

24.1 Introduction

In India, the commercial cultivation of oil palm started during 1970. Today about 16 countries of tropics cultivate oil palm. The palm oil has been safe and nutritious source of edible oil for human consumption for 1000 years. Palm oil and its liquid fraction palmolein is consumed worldwide as cooking oil. Malaysia, Indonesia, Nigeria and Columbia started to grow oil palm in a large scale during 1980. The commercial producing countries are Liberia, Peru, Angola, Senegal, Ghana, etc.

23.1 Introduction

Coffee is the second important popular beverage for its aroma and mild stimulant action. Its dried beans are roasted, ground and brewed to make a stimulating and refreshing beverage. Use of coffee has evolved from original chewing of leaves and beans of the plant to relieve pain, hunger and fatigue to the present more sophisticated uses, like espresso and decaffeinated coffees. Its use was first discovered in Arabia around mid-15th century.

22.1 Introduction

Tea is the most important non-alcoholic beverage gaining further popularity as an important “health drink”. It is consumed as a morning drink by 2/3rd of world population. Tea was initially used as a medicine and subsequently as beverage and now has proven to be a potential raw material for pharmaceutical industry. Tea is mainly consumed in the form of ‘fermented tea’ or ‘black tea’, ‘non-fermented tea’ or ‘green tea’ and ‘semi-fermented tea’ or ‘oolong tea’. Green leaves are also used as vegetables such as ‘leppet tea’ in Burma and ‘meing tea’ in Thailand. Tea leaves have more than 700 chemical constituents among which flavonoids, amino acids, vitamins (C, E, K), caffeine and polysaccharides are important to human health. The stimulating effect of tea is due to caffeine (1.25-4.5%). Per cup value of caffeine in tea is three and half times less than that of coffee and is less harmful than coffee. Importantly, the vitamin C content in leaves is comparable to that of lemon.

21.1 Introduction

Cashewnut or cashew is an export-oriented crop grown for its nuts, a true drupe. It is often referred to as ‘wonder nut’. It is highly delicious and nutritive. Its nutritional composition compares well with almond, hazelnut and walnut. The economic part is kernel which is a unique combination of fats (47%), protein (21%), carbohydrates, minerals and vitamins. Nutritionally it is equivalent to milk, egg and meat, it is good appetizer, an excellent nerve tonic, stimulant, body builder. India is the largest producer, processor and exporter; and second largest consumer in the world. Cashew is grown in Kerala, Karnataka, Goa and Maharashtra along the west coast and in Tamil Nadu, Andhra Pradesh, Odisha and West Bengal along the east coast.

20.1 Introduction

Arecanut (or betel palm) is chewed as narcotic either alone or more commonly along with betel leaf. Its nut has medicinal and pharmaceutical properties. About 1/10th of world population has a habit of betel chewing. Nut contains polyphenol (11-18 %) which includes flavonols like catechin, epicatechin, leucocyanidin, fat (9-15%), polysaccharides (17-25%), fibre and protein (6- 7.5%) and some minerals like calcium, phosphorous and iron.

19.1 Introduction

Coconut is valued most for its nut. The other components are coconut water, kernel, shell and husk. Coconut water is one of the most refreshing drinks. It is also known for its medicinal value. It increases blood circulation in kidneys, causes profuse diuresis and eliminates mineral poisoning. It is a good substitute for saline glucose under gastroenteritis conditions. The coconut has been regarded as ‘Kalpavriksha’ because all the parts of the palm is useful to mankind in one way or other. The dried kernels commonly called as copra is the richest source of vegetable fat (60-67 % oil). Coconut is major source of edible oil. India is the largest producer of coir and its product. The major coconut growing areas of the world are found in Asia, Oceania, West Indies, Central South America, East and West Africa. In India, coconut is commercially grown in Kerala, Karnataka, Tamil Nadu, Andhra Pradesh, Gujarat, Odisha and West Bengal.

18.1 Introduction

Among nut crops, ‘Walnut’ or ‘Akhrot’ is the most important crop. It has immense commercial importance even in the areas situated in remotes without having good market and transport infrastructure. Because of long storability, growers have opportunity to hold the produce at room temperature for two to three months easily and sell out at intended time. Walnut is rich in protein, fats and vitamins, especially vitamin B6 . The walnut kernel contains about 90% PUFA of which 26% is the Omega-3 fatty acid, alpha-linolenic acid. But the problem with this type of kernel is that higher the percentage of PUFA in it, the more is the chances of getting the oil oxidized and thereby reducing the shelf life of the walnut kernel.

17.1 Introduction

Almond or badam is a high energy nut. Almond kernels contain lipids (52.2%), protein (20%), carbohydrate (20.4%) and water-soluble sugars (4.4%). Irrigation affects almond yield and quality. Almond quality is primarily genotype dependent. Maturity at harvest can also influence kernel quality.

16.1 Introduction

Peach is one of the important fruits grown in warm temperate zones of the world. Fruits are rich in protein, sugar, minerals and vitamins. Peaches are highly valued as table fruit for their attractive colour and palatability. Canned peaches, dried frozen preserves, jams, nectar are principal processed products of peach. It is grown mainly in Jammu and Kashmir, Himachal Pradesh, Punjab, Uttarakhand, Nilgiri hills, Jharkhand and North-Eastern States.

15.1 Introduction

Pear is one of the important fruit crops that belong to the family Rosaceae. In the world pear is cultivated in China, USA, Argentina, Italy, Turkey, Spain, India, South Africa, Japan, Belgium etc. It is grown under a wide variety of climatic regimes ranging from cold dry temperate hilly conditions to warm humid sub-tropical conditions on the plains of northern India. In India pear is widely cultivated in Punjab, Himachal Pradesh, Jammu and Kashmir, Uttar Pradesh, Uttarakhand etc.

14.1 Introduction

Apple is the most widely grown temperate fruit of the world. It is considered as King of temperate fruits. It is rich in carbohydrate, calcium, phosphorous, iron, potassium, vitamin B6 . Apple is rich in antioxidant, flavonoids and dietary fibre. It is recommended to reduce the incidence of dental caries. The phytonutrients and antioxidants may help reduce the risk of developing cancers, hypertensions, diabetes and heart disease. Apple is mainly used for table purpose. The various processed products are prepared from fruit, e.g., juice, jelly, preserve, canned slice, wine, concentrated juice, cider and powder. It is widely cultivated in Afghanistan, Armenia, Azerbaijan, Bhutan, China, India, Indonesia, Iraq, Iran, Israel, Japan, Jordan etc.

13.1 Introduction

Pomegranate (Punica granatum L.), an economically important fruit plant species, belongs to the family Punicaceae. It is an important fruit crop of arid and semiarid regions of the world and has been believed to be the symbol of fertility and abundance. Pomegranate is a highly remunerative crop for replacing subsistence farming and alleviating poverty. The plant is drought tolerant, winter hardy and can thrive well under desert condition. It is a good source of protein, carbohydrate, minerals, antioxidants, vitamins A, B and C, and has also been used in controlling diarrhoea, hyperacidity, tuberculosis, leprosy, abdominal pain and fever. Pomegranate juice contains antioxidants such as soluble polyphenols, tannins, anthocyanins and can be used in the treatment of cancer and chronic inflammation. It has enjoyed a reputation for its healthy dietetic and medicinal properties.

12.1 Introduction

Aonla (also called Amla, Indian gooseberry) is a tropical and sub-tropical fruit. It is mainly recognized due to its high nutritive, medicinal and therapeutic properties. It contains high amount of vitamin C (500-1500 mg/100 g); it is also rich in pectin, iron, calcium and phosphorus. Dried fruits of aonla are used in curing haemorrhage, diarrhoea, chronic dysentery, diabetes, jaundice, dyspepsia, cough etc. Aonla is the main ingredient of Chavanprash and Triphala powder. The fruit contains gallic acid and leucoanthocyanin which have antioxidant property. Its cultivation is more common and widely grown in Uttar Pradesh, Gujarat, Rajasthan, Madhya Pradesh and Tamil Nadu.

11.1 Introduction

Ber (also called Indian Jujube, Indian Plum, Chinese Apple and Masau) is an important minor fruit of India. It is most widely cultivated in Punjab, Haryana, Rajasthan, Uttar Pradesh, Madhya Pradesh, Bihar, Gujarat, Maharashtra etc. Fruits are mostly eaten fresh but other forms, such as dried, candied, squash etc. can be prepared from ber. Stem, bark, root and leaves have some medicinal values. Leaves of ber are used as fodder in dry regions.

10.1 Introduction

Litchi is a delicious fruit and generally consumed as a table fruit. It is one of the most popular fruits in India. It is also recognized as “Queen of Fruits”. It is a subtropical evergreen fruit crop. Its climatic requirements are highly specific. Thus, its commercial cultivation is restricted to only a few subtropical countries of the world. The major litchi producing countries are China, India, Taiwan, Thailand and Vietnam. In India, the important litchi growing states are Bihar, Jharkhand, West Bengal, Tripura, Uttar Pradesh, Uttarakhand, Chhattisgarh, Punjab and Himachal Pradesh. Litchi makes an excellent canned fruit and highly flavoured squash is prepared from inferior fruits.

9.1 Introduction

Pineapple is one of the most important commercial fruits of the world. It is good source of vitamin A, B and fairly rich in vitamin C, minerals like calcium, phosphorous and iron. Fresh fruit is used as dessert. Fruit is also used for juice, squash, jam, mixed jam and in canned form. Fruit core is used for preparing candy. Some cultivars of pineapple are used for extraction of fibre. The important pineapple growing states are Assam, West Bengal, Tripura, Kerala, Andhra Pradesh, Bihar, Karnataka and Madhya Pradesh.

8.1 Introduction

Guava is the fourth important fruit crop next to mango, banana and citrus. It is known as the ‘Apple of tropics’. It is very rich and cheap source of Vitamin C and also contains a fair amount of calcium. Important guava growing states are Uttar Pradesh, Bihar, Madhya Pradesh and Maharashtra. Allahabad district of Uttar Pradesh has the reputation of growing the best quality of guava fruits in the world. The importance of guava is due to the fact that it is the hardy fruit which can be grown in alkaline and poorly drained soil. Guava fruits are used for making jam, jelly and various culinary purposes. The fruit can be canned in sugar syrup.

7.1 Introduction

Papaya is a fruit crop grown in kitchen garden, backyards of home and orchards. It is grown as a filler crop in orchard. India is the largest producer of papaya in the world. It is also cultivated in Brazil, Mexico, Australia, Hawaii, Malaysia, Taiwan, Peru, Florida, Gold Coast, South Africa and Bangladesh. In India, it is widely cultivated in Uttar Pradesh, Bihar, Karnataka, Jharkhand and Madhya Pradesh. The ripe fruits of papaya are consumed throughout the tropics and sub-tropics. Fruits are also used in the preparation of jam, soft drinks, ice cream flavour, crystallized fruits and syrups. Unripe fruits are commonly used as vegetables. Papain is prepared from the latex of immature fruits. It is a proteolytic enzyme used for tendering of meat, preparation of chewing gum and cosmetics. The ripe fresh fruit is rich source of vitamin A, carbohydrates and minerals. The fruits are prescribed for piles, dyspepsia, liver, spleen and digestive disorders. Roots are used as nerve tonic. The plants flower five months after planting and fruits are ready five months after flowering. So, it has attracted attention of fruit growers to cultivate on a large scale in the country.

6.1 Introduction

Grapes are being grown commercially in the tropics. The region between the tropics of Cancer and Capricorn which was once considered to be unsuitable for growing quality grapes is producing good quality grapes. Tropical countries where grapes are grown are India, Indonesia, the Philippines, Thailand, Taiwan, South China, Australia, Brazil, Columbia, Ecuador, Mexico, Venezuela, West Indies, Kenya, Nigeria and Zimbabwe. In India, about 90% of grapes are being produced in the tropical states including Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu. There are three main commercial uses of grape, viz., table, raisin and wine.

5.1 Introduction

Citrus is one of the most important fruit crops in the world. It is grown in the tropical and sub-tropical regions of the world. The top ten citrus producing countries are China, India, Nigeria, Brazil, Mexico, USA, Spain, Egypt, Italy and Argentina. The citrus industry in India is the third fruit industry after mango and banana. The important groups of crops in citrus are sweet orange, mandarins, limes, lemons, grape fruits and pummelo. The most important commercial Citrus species grown in India are mandarin (Citrus reticulata Blanco.), followed by sweet orange (Citrus sinensis (L.) Osbeck) and acid lime (Citrus aurantifolia Swingle). The major citrus producing states are Maharashtra, Karnataka, Andhra Pradesh and Punjab.

4.1 Introduction

Banana (Musa spp.) is one of the oldest fruits and second largest growing fruit crop in the world. It is also known as Adam’s Fig and Apple of Paradise. Important banana growing states are Maharashtra, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Odisha, Bihar, West Bengal and Assam. In South India, banana is extensively used in all auspicious occasions such as wedding, festival and worship. Banana is a good table fruit. The cultivar Nendran is used for cooking; it is also used for preparation of halwa, sweet, chips etc. Main bud or heart of banana bunches is also used as vegetable in India, Thailand, Philippines, Malaysia and Indonesia. Musa textiles is known for strong fibre quality. Ripe banana contains about 20% sugar (but no starch) and about 4.7% protein. Further, it contains vitamins A, B, C, D and E and minerals such as K, P, Ca and Fe.

3.1 Introduction

The Mango (Mangifera indica L.) belonging to the family Anacardiaceae in order Sapindales, is amongst the most important tropical fruits of the world. In India, it is also known as the ‘king of fruits’ owing to the delicious quality of the fruit rich in vitamins and minerals. Its long period of domestication is evident from its mention in the ancient Indian scriptures. In India, mango has been valued not only for religious consideration but also for its importance in the economic and cultural life of the society. Mango is rich in Vitamin A and C, flavonoids, carotenes, glucosides, sterols, terpenes, aromatic acids, essential oils, fatty acids and phenolics. It is a powerful nutritive fruit, containing most of the essential substances needed by the human body. The most important single factor limiting the production of mango fruit at the present time is the erratic fruiting habits of this species. Some cultivars produce a good crop in most years and a poor crop in other years, while still other cultivars produce only a few fruits each year. For many years new cultivars have been selected and grown on the basis of size, appearance, and dessert quality with very little attention given to their production capabilities. The improvement of mango needs to explore new recombinants primarily by means of exploiting the breeding methodologies. Diversity or heterogeneity is the main character desired for breeding either natural or manmade. It is required to have vast genetic pool to get new combinations of desired nature and developing new hybrids. It has been mentioned earlier that the development of mango in India is the result of selection from the amateur gardeners. Now, the scientists have developed certain hybrids of mango.

2.1 Introduction

The different breeding strategies (methods) that can be employed for improvement of fruit crops include introduction, open pollinated selection, clonal selection, hybrid breeding, polyploidy breeding, mutation breeding, molecular breeding, in vitro breeding and transgenic breeding. Combining traditional approaches with biotechnological approaches will speed up the rate of genetic improvement. Thus, what is required is to adopt a coordinated approach involving breeders, biotechnologists, horticulturists, pathologists, entomologists and statistician for making the cultivation of fruit crops more scientific and more profitable and thereby contributing more to improving the health of the people in a sustainable manner.

1.1 Introduction

Fruit breeding is an ancient technology with dynamic current technology and an exciting future (Janick and Moore 1975, 1996). In its broadest sense, fruit breeding refers to the purposeful genetic improvement of fruit crops through various techniques including selection, hybridization, mutation induction and molecular techniques. Its origins trace to the domestication process in prehistory and antiquity, where useful species were chosen and cultivated, and improved by continuous selection (Janick 2005, 2011). Through the millennia genetic improvement of these species have been achieved by grower selection, first from natural seedling populations and then from grower field that continued unique genotypes fixed by vegetative propagation. Spontaneous hybridization between wild plants and cultivated clones was critical to the early domestication of fruits.

Botanical Name: Hevea brasiliensis

Family: Euphorbiaceae

Chromosome No: 2n =36

Place of Origin: Amazon basin in Brazil

Common Name: Rubber tree, Rubber plant, Para rubber tree

11.1 Introduction

Rubber is a fast-growing tropical tree and mainly grown for the production of latex. In 1495, Columbus was the first person to report about latex. The latex was used for rub out pencil marks and this gave the product name as rubber. The latex is used for production of various rubber products. The most important application of latex rubber was initially accomplished in the 1880s when the rubber was used for making motor cars tyres. When rubber is heated with sulphur, it retains the physical properties.

Botanical Name: Camellia sinensis L.

Family: Theaceae

Chromosome No: 30

Place of Origin: China

Common Name: Tea

9.1 Introduction

Tea (Camellia sinensis L.) of family Camelliaceae or Theaceae is the oldest and second most widely consumed beverage in the world following water. Tea is an evergreen plant that mainly grows in tropical and subtropical climates. India is world’s 2nd largest tea producer after China with production of 1.25 million tonnes in 2020. In India it is grown in an area of 6 lakh hectares, contributing one fourth of world total tea production annually. Interestingly, India is also the world’s largest consumer of the beverage and using nearly 30 percent of the world’s tea output. India stands third in terms of tea export after Kenya (including neighbouring African countries) and China. The total tea export was US$ 501.16 million in April 2020 to November 2020 and for November 2020 it was US$ 71.61 million.

Botanical Name: Coffea arabica, Coffea canephora

Family: Rubiaceae

Chromosome No: 44, 22

Place of Origin: Africa

Common Name: Coffee

8.1 Introduction

Coffee is widespread throughout the tropics with more than 70 species. All cultivated species originate from Africa. Economically important today is Coffea arabica (Arabica, 64 % of world production) and Coffea canephora, (Robusta, 35 %). It is cultivated worldwide on approximately 10.3 million hectares and represents the sole economic income for more than 25 million families. The crop is produced and exported by more than 60 nations and ranks as one of the top cash crops in developing countries with 3.19 lakh MT production per annum in India in 2018-19 from more than 459 thousand hectares crop area. The coffee plant is a fast-growing tropical bush tree, with two types of shoots: upright growing orthotropic main shoots (stem), and horizontally growing plagiotropic shoots (branches). Traditionally, coffee trees are cultivated only for the berries, which are processed using dry or wet techniques directly in the growing areas to the final raw product, green coffee; this serves as the basis for various coffee products. Both the coffee species tolerate shade and share quite similar growth requirements with various forest crops and trees, thus predisposing them to be grown in agro-forestry ecosystems.

Botanical Name: Anacardium occidentale L.

Family: Anacardiaceae

Chromosome No: 42

Place of Origin: Brazil

Common Name: Cashew, cashew tree, caju

7.1 Introduction

Cashewnut (Anacardium occidentale L.) is an important tropical tree crop which leads the edible nuts in international trade with 29% market share only after hazelnuts (35%) and followed by walnuts (21%) and almonds (16%). It is one of the major exports earning crops which accounts nearly Rs. 2515 crores contributing about 1.5% of the total Indian exports. It was only during the past two decades it gained the status of horticulture crop. India is the world’s largest producer of cashewnut. The cashew cultivation area in India during 2018-19 was 10.89 lakh hectares with an annual production of 743 thousand metric tons of fruits. Maharashtra is a much-advanced state for horticulture which occupies large area (1.9 lakh hectares) under this crop (Directorate of Cashew & Cocoa Development, Cochin, Kerala). Cashew exports amounted to over 566 million U.S. dollars from India in fiscal year 2020. This included cashew kernels and cashew nut shell liquid. India’s main export markets for this commodity included South Korea, China, Spain, United States and Belgium (Department of Agriculture, Cooperation & Farmers Welfare).

Botanical Name: Theobroma cacao L.

Family: Sterculiaceae

Chromosome No: 20

Place of Origin: Tropical South America

Common Name: Cacao, cacao bean, cocoa, cocoa bean

6.1 Introduction

Cocoa (Theobroma cacao L.) is a perennial plant and is used as beverage crop. The generic name Theobroma means the “Food of the God”. The word cacao refers to the tree, while the word cocoa refers to the drink made from its seeds. The roasted product of the dried beans is called as Cacao nibs that are used for the manufacture of various products. When cacao nibs are ground, the resulting product is called chocolate liquor or mass, which contains around 55% fat. The fat that is pressed from chocolate liquor is termed as cacao butter. It is mainly used for the manufacture of chocolates, in pharmaceutical preparations and soap making. After pressing out the fat the resultant product with reduced fat content is called cacao powder. For preparation of chocolates cacao powder is mixed with cacao butter and sugar with a definite ratio. Milk chocolates are prepared by adding milk to the above mixture. The cocoa powder contains 22- 25% fat, 20.4% protein and 35% carbohydrate with caloric value of 452 cal. Rind or shell of pod is used as a cattle feed.

Botanical Name: Borassus flabellifer L.

Family: Arecaceae

Chromosome No: 36

Place of Origin: Tropical region of Africa, Asia and New Guinea

5.1 Introduction

Palmyrah is a monocotyledon and perennial crop. The word “Borassus” was derived from a Greek word and it means the leathery covering of the fruit and “flabellifer”, means fan-bearer. The distinguishing characters of palm in this genus are their palmate, fanlike leaves and dioecious character, i.e., male and female flowers are borne on separate trees (sex ratio 1:1), allotetraploid (X= 8 or 9, n = 18), the male tree has a heteromorphic XY pair of chromosomes while the female has an XX pair (Sankaralingam et al., 1999). Next to coconut, palmyrah is the most abundant palm found in the world. Palmyrah thrives in arid conditions and is grown extensively in Tamil Nadu. Palakkad district of Kerala is popularly known as land of palmyra trees. Palmyra trees are known as the icon of this district and have a vast cultural, heritage and literary association.

Botanical Name: Elaeis guineensis Jacq.

Family: Arecaceae / Palmae

Chromosome No: 32

Place of Origin: Guinea Coast of West Africa

Common Name: Oil Palm

4.1 Introduction

The cultivated oil palm Elaeis guineensis Jacq. is a native of West Africa and exists in wild, semi- wild and cultivated forms. It was introduced as an ornamental crop in 1860 and planted at National Botanical Garden, Kolkata. Research on oil palm in India started during 1960 with the establishment of a research station at Thodupuzha by the Department of Agriculture, Kerala with Dura and Tenera germplasm imported from Malaysia and Nigeria. National Research Centre (NRC) for oil palm is situated at Elur, Andhra Pradesh. Oil palm crop is one of the highest oil yielding crops among all perennial crops. It gives 4 to 6 tonnes of edible oil/ha from 3 to 25 years of its life span compared to less than one tonne of oil per ha from other cultivated oil yielding crops. This oil palm is considered as golden palm due to its high yielding capacity. Among the 10 major oilseeds, oil palm is accounted for 5.5% of global land use for cultivation, but produced 32.0% of global oils and fats output.

Botanical Name: Cocos nucifera L. Family: Arecaceae / Palmae Chromosome No: 32 Place of Origin: Malaysia Common Name: Coconut 2.1 Introduction Coconut (Cocos nucifera L.), is widely known as ‘Kalpavriksha’ (i.e., tree of heaven) as each and every part of the palm is useful in one way or the other and is an important perennial oil yielding crop of humid tropics. It provides food security and livelihood opportunities to 20 million people around the globe and 10 million people in India (Chowdappa et al., 2017). Even though India is the largest coconut growing country in the world, its contribution to the export market is not significant. Coconut as an edible oil and food crop, is now slowly transforming into raw material for various pharmaceutical, nutraceutical and cosmetic products. Coconut is rich in fibre, vitamins and minerals. Because of its health benefits beyond its nutritional content, it has been considered as “functional food”. Hence, there exists a huge scope for coconut-based agribusiness in India, which will increase the present 8% level of value addition to 25%. The coconut-based value-added products are desiccated coconut powder, coconut milk, coconut cream, coconut milk powder, coconut flour, coconut water concentrate, coconut jelly (Nata-de-coco), coconut vinegar, virgin coconut oil, coconut chips, coconut pickle, coconut ice cream, neera and neera based value added products such as syrup, squash, honey, jaggery, candy and sugar (Chowdappa et al., 2017).

Botanical Name: Phoenix dactylifera L.

Family: Arecaceae

Chromosome No: 2n = 36

Place of Origin: Countries around Persian Gulf

10.1 Introduction

Date palm is a nutritive fruit rich in sugar and iron and predominantly seen in desert oasis. It is the main fruit crop in arid and semiarid regions, particularly in the arid regions of western Asia and North Africa. The palm tree is well adapted to desert environments that are characterized by extreme temperatures and water shortage. Beyond the arid climates, date palm can also be grown in many other countries for food or as an ornamental plant including the continents of Americas, Southern Europe, Asia, Africa and Australia. The majority of date palm growing areas are located in developing or underdeveloped countries where dates are considered the primary food crop, thus playing a major role in the nutritional status of these communities. By-products from date palm are used in building structures, animal feed, and also in several items such as baskets and ropes. The date palm tree has been in cultivation since 2400 BC. It is one of the oldest cultivated fruit trees on earth. India is the leading importer of dates. According to FAO statistics, in 2011 India was the largest world importer of dates (256,295 mt) and its neighbour Pakistan, in 2012, was the world’s sixth largest producer (600,000 mt). The major date palm growing areas in India are Kutch (Gujarat), Rajasthan and certain parts of the Punjab, as well as Tamil Nadu state to some extent. In Kutch, there are more than 2 million date palms, the majority of them grown from seeds and offshoots, providing a huge biodiversity for experimentation and improvement of products. Efforts by the Indian government in the last decade have resulted in an increase of date palm cultivation from 8,973 to 16,000 ha and establishment of a prominent effort in Rajasthan (Shah, 2014).

Botanical Name: Areca catechu L. Family: Arecaceae / Palmae Chromosome No: 32 Place of Origin: Philippines, Malay, Indonesia, Cochin, China and Malaya Peninsula Common Name: Betel nut 3.1 Introduction Arecanut (Areca catechu L.), commonly known as Supari or Betel palm or Arecanut palm, is cultivated primarily for its kernel obtained from the fruit which is chewed in its tender, ripe or processed form. It is an important cash crop of India. The economic produce is the fruit called ‘betel nut’ and used mainly for masticatory purposes. Its cultivation is restricted in South Western and North Eastern regions of the country. The chromosome number of Areca catechu L. was first determined as 2n=32 (Venkatasubban, 1945) and it belongs to family Arecaceae. It is one of the important commercial crops grown in parts of Karnataka, Kerala, Assam, Meghalaya, West Bengal, and Andaman and Nicobar Islands. The cultivation of arecanut has also been extended to other states like Tamil Nadu, Andhra Pradesh and Maharashtra. India is the largest producer and consumer of arecanut in the world holding 62% of the area and 60% of the production. The other major arecanut growing countries are Indonesia, Bangladesh, China, Myanmar and Thailand. Arecanut being a profitable plantation crop, it is important to understand the package of practices and seasonal operations to be followed in the nursery, in young gardens and in old plantations to get maximum returns. To get additional income in the adverse periods, concept of cropping system is very important. The exact origin of areca nut is not known till date but, arecanut is a palm which grows in much of the tropical Pacific, Asia, and parts of East Africa (Kumar, 2013).

Threats

There are sixteen threat factors have been identified from Indian mangroves (Kathiresan 2010). However, habitat conversion for agriculture and aquaculture activities, environmental pollution by upstream anthropogenic activities, Climate change processes (e.g. sea level rise; increasing frequency of cylones, etc.) are the major threat factors for mangroves. Mangroves are able to cope up with short-term oscillations and long-term fluctuations of climatic conditions, but the consequences of global climate change, such as increased extreme events, will have unprecedented effects on biota and threaten the resilience and recovery potential of the ecosystems (Harris et al. 2018; Sippo et al. 2018). Despite conservation measures, the mangroves still experience an annual loss of 0.2-0.7% during 2000-2012 and they remain the most threatened ecosystem of the world (Hamilton and Casey 2016).

Mangrove forests are ecologically significant and economically important (Kathiresan 2018). They provide ecosystem services worth at least US$ 1.6 billion each year and support coastal livelihoods worldwide (Costanza et al. 1997). They serve as the nursery, feeding and breeding grounds for crabs, prawns, molluscs, finfish, birds, reptiles and mammals. A large amount of global fish catches (up to 80%) is dependent on mangroves, thereby ensuring the food security of coastal people (Ellison 2008). The mangroves provide firewood, timber, cattle feed, honey, medicines and tourism development. They protect groundwater aquifers from seepage of seawater, thereby ensuring water security for coastal population. Mangrove forests remove coastal pollution particularly toxic heavy metals. They offer coastal protection against the fiery effects of natural calamities such as tsunami, storm surges, cyclone and floods (Kathiresan and Bingham 2001; Kathiresan and Qasim 2005; Kathiresan and Rajendran 2005). The potential of mangroves in carbon capture and sequestration is remarkable in mitigating the impacts of global warming and climate change (Kathiresan et al. 2013, 2014).

West Bengal

In West Bengal, mangroves are present in Sundarbans, the large deltaic complex of three major rivers, the Ganges, Brahmaputra and Meghna, and 62% of total area is shared by Bangladesh and 38% by India. The Sundarban Biosphere Reserve (SBR), at the confluence of the Bay of Bengal covering an area of 9,630 km², lies between 21°40′N and 22°40′N latitudes and 88°03′E and 89°07′E longitudes, spreading in districts of South and North 24-Parganas in West Bengal, India. The major portion of SBR is designated as Reserve Forest, covering nearly 4260 km² and the area under mangrove vegetation is 2112 km² (FSI 2019). Compared to 2017 assessment there has been a decrease of 2 km² area of mangroves. The mangroves and their associates in the SBR exhibit great generic and species diversity and it is abode to rare and highly endangered flora and fauna, as well as, the only mangrove-tiger (Royal Bengal Tiger - Panthera Tigris tigris) kingdom in the world. Recognizing importance and uniqueness, the United Nations Educational, Scientific and Cultural Organization (UNESCO) declared the Indian part of Sundarbans as a ‘World Heritage Site’ in 1987, and also designated the ‘Sundarban Biosphere Reserve’ under the UNESCO Man and the Biosphere (MAB) program in 2001. Recently, Sundarbans has been declared as a Ramasar Site, considering ecological significance. Totally 33 true mangrove species belonging to 21 genera and 13 families have been identified in Indian Sundarbans. Among the mangrove species listed, Rhizophora apiculata, Bruguiera parviflora, Ceriops decandra, Kandelia candel, Aglaia cucullata, Excoecaria indica, Xylocarpus moluccensis, Xylocarpus granatum, Heritiera fomes, Scyphiphora hydrophyllacea, Brownlowia tersa, Nypa fruticans, Acanthus volubilis, Dolichandrone spathacea and Phoenix paludosa are under serious threat in Sundarbans (Kathiresan 2008; Gopal and Chauhan 2006). Particularly Heritiera fomes (locally called Sundari, from which Sundarbans derives its name), Nypa fruticans and Phoenix paludosa are declining rapidly due to the reduction of freshwater input (Gopal and Chauhan 2006).

Distribution of Mangroves in India

Mangrove forests in India are found along the coastline of 9 States and 4 Union Territories (Fig. 5). The mangrove habitats are broadly classified into three namely, Deltaic (Eastern Coast Mangroves), Estuarine & Backwater (Western Coast Mangroves) and Insular mangroves (A & N Islands) (Mandal and Naskar 2008). India has a total mangrove cover of 4975 km²; of which, 57% is present along the east coast (Bay of Bengal); 31% along the west coast (Arabian Sea) and the remaining 12% in the Andaman and Nicobar Islands (FSI 2019).

Origin and diversification of Mangroves

Mangroves are quite old, possibly arising just after the first angiosperms (Duke 1992). Based on the fossil evidence and recent molecular studies, it is believed that mangroves originated along the shorelines of ancient Tethys Sea and there was a dispersal along the Tethys seaway westward into the Atlantic and further into the east Pacific (long before the closure of the Panama Isthmus) and eastward into South east Asia and Australia during the Late Cretaceous or early Eocene around 80 million years ago (Duke 2006). Nypa seems to be earliest fossil evidence. However, prior to closure of Tethys sea, around 40-55 million years ago, the mangrove genera - Nypa, Acrostichum, Rhizophora, Avicennia, Pelliciera, Sonneratia, Bruguiera, Ceriops, Heritiera, and Aegiceras - were present around shoreline (Duke 2017). The closure of Tethys Seaway by the mid-Tertiary (34-50 Million years ago) by northward movement of African landmass, created a physical barrier that completely terminated the Atlantic East Pacific (AEP) and Indo-West Pacific (IWP) exchange route, and resulted in subsequent diversifications within the AEP and IWP regions influenced by region-specific events (Ellison et al. 1999; Duke 2006). The plate tectonics and other vicariant events like Pleistocene sea level rise are attributed to the current distribution pattern and disjunct distributions of species within genera. Duke (2017) hypothesised two separate westward dispersal routes in AEP: (i) a southern path along the coasts of West Africa, South America and, (ii) a northern path along the North American east coast, whereas he hypothesised two isolated pathways in IWP towards eastward dispersal: (i) a northern path along the coast to the Middle East, Southeast Asia and, (ii) a southern path along the coasts of East Africa, India, and Australia. Further he noted that collision of India and Australia with Middle East and Southeast Asia respectively, resulted complication in dispersal route. Based on the available records it is presumed that diversification of mangrove plants has largely been driven by three key processes of speciation viz., Allopatric speciation, Peripatric speciation and Parapatric speciation (Duke 2017).

Mangroves Definition

A mangrove is tree, shrub, palm or ground fern, generally exceeding one and a half meter in height that normally grows above mean sea level in the intertidal zone of marine coastal environment and estuarine regions of the tropical and subtropical coastlines (Duke 1992). The mangrove is also defined as assemblages of salt tolerant trees and shrubs. Mangroves are taxonomically heterogenous and more related to environment than terrestrial or aquatic plants.

The term ‘mangroves’ is used to define both a group of plants and a community. To avoid confusion, Macnae (1968) proposed the term ‘mangal’ for the mangrove forest community, and the term ‘mangroves’ for the plants. Other terms for the mangrove forest community are coastal woodland, oceanic rainforest, intertidal forest, tidal forest, blue carbon forest, mangrove forest, and mangrove swamp.

Generally, mangrove species are grouped into two types: Exclusive and Non-Exclusive. The exclusive species are limited to the mangrove habitat, and they are also referred to as strict mangroves, obligate mangroves or true mangroves. The non-exclusive species are mainly distributed in a terrestrial or aquatic habitat, but they also occur in the mangrove habitats and they are referred to as semi-mangroves, back mangroves or mangrove associates. Tansley and Fristch (1905) are the first to introduce the criteria to classify mangrove species into true mangroves and mangrove associates. Tomlinson (1986) used rigid criteria to distinguish true mangroves from mangrove associates. In his criteria, true mangroves possess all or most of the following features:

29.1 Introduction

An environmental factor that interferes with the complete expression of genotypic potential of a crop is called stress. The stresses may be biotic (pathogens, insect-pests, etc.) or abiotic. The main abiotic stresses are drought, mineral deficiency/toxicity and heat or cold. The losses due to abiotic stresses can be minimized by:

Crop management: The degree of stress can be reduced by suitable agronomic/soil management practices, e.g., irrigation to relieve drought stress, soil amendments to reduce salinity.

Development of resistant cultivars: This offers the cheapest, easiest to apply and most eco-friendly approach to reduce losses due to any stress.

Indirect breeding: Evaluation of materials under stress often helps in identification of a resistant line that may become an important commercial cultivar.

???????Direct breeding: It is deliberate breeding of materials for stress resistance. When a genetically variable material is grown under the stress environment, selection can be based on survival, yield and other traits contributing to stress resistance.

28.1 Introduction

The stress that is caused by biological agents or factors such as diseases, insect-pests and parasitic weeds is called biotic stress. The term disease can be broken into two words: “dis” (means negative, reverse or opposite) and “ease” (means comfort, or freedom from pain or discomfort). Hence, plant disease can be defined as any harmful alteration from the normal functioning of physiological processes. Diseases may be bacterial, fungal or viral. A wide range of insects infests various crop plants. The extent of damage caused to crop plants by various organisms is usually in the order fungi > bacteria > viruses > nematodes = insects. But the relative importance of these organisms varies to a great deal in different crops. Breeding of cultivars resistant to diseases and/or insect-pests is the cheapest, safest and most dependable means of limiting the losses due to them. Resistant cultivars form an important component of integrated management of diseases and insect-pests.

28.2 Breeding for Resistance to Biotic Stresses-Diseases

Agrios (1970) has defined disease as: “Disease is a series of invisible and visible responses of plant cells and tissues to a pathogenic microorganism or an environmental factor that result in adverse changes in form, function or integrity of plant and may lead to partial impairment or death of the plant or its parts.” The organism causing disease is called pathogen, while the plant affected by the disease is called host.

The principles underlying breeding for resistance to diseases are much the same as for other characters, except for one important difference, i.e., the diseases caused by pathogens are the product of interaction between two genetic systems, that of the host and that of the parasite. Both systems are capable of variation and evolution and affect the interaction between host and pathogen. Here the breeder is required to deal with the heritable traits of both the host plant and the pathogens invading it.