eChapters

1. Anthracnose
Colletotrichum gloeosporioides (Glomerella cingulata)
Diagnostic Symptoms
• Disease produces symptoms like leaf spot, blossom blight, withertip, twig blight and fruit rot .
• Symptoms on leaves show as gray to brown spots with dark margins and a yellow halo. The spots later enlarge and coaleasce to form sizable necrotic areas.
• Tender shoots and foliage are easily affected which ultimately cause die back young branches.
• Blossom blight may vary in severity from slight to a heavy infection of the panicles .
• Black spots develop on panicles as well as on fruits. Severe infection destroys the entire inflorescence resulting in no setting of fruits.
• Young infected fruits develop black spots, shrivel and drop off.
• Fruits infected at mature stage carry the pathogen into storage and cause considerable loss during storage, transit and marketing (Figure -1).

Mango (Mangifera indica L), the king of fruits, is cultivated throughout a wide range of frost-free climates (Litz 1998). It is commercially the most important fruit crop of India, accounting for more than 54% of the total mango production worldwide. The fruit of mango (Mangifera indica L.) is exceptional for its juicy, succulent, thick fruit pulp and nutrient abundance in terms of wide range of amino acids, sugars, organic acids, minerals including Ca, P, Fe, and K and vitamins. Out of several diseases which attack mango crop, mango malformation disease is a serious threat to its cultivation since it causes gross deformation of the vegetative and floral tissues (Ploetz et al., 2002; Kumar et al., 2011). Floral malformation is a major problem in mango, rendering mango cultivation unproductive in northern India and other regions of the world (Pandey et al., 1977; Ram, 1991).

Important Commercial Mango Varieties

Northern Region: Langra, Dashehari, Chausa, Bombay Green, Amrapali, Sukul, Sipia

Eastern Region: Himsagar, Langra, (syn. Malda), Krishna-Bhog, Zardalu, Gulabkhas, Fazli.

Southern Region: Banganapalli, Bangalora, Mulgoa, Neelum, Swarnarekha,

Western Region: Alphonso, Kesar, Pairi.

It is a very common disease of mango. It is otherwise known as blossom blight, leaf spot, twig blight or wither tip.

Mango, Mangifera indica is indigenous to India and ranks at number one as for as production and export are concerned. The productivity of mango in India is low (6.6MT/ha) and one of the reasons for the same is pests associated with the crop at varying stages of the tree growth. Around 175 insect pests have been reported to infest mango but only few are the major pests the details of which re provided hereunder:

Mango hopper, Idioscopus clypealis (Lethiery); I. niveosparsus (Lethiery); Amritodus atkinsoni (Lethiery) (Cicadellidae: Hemiptera) Hoppers constitute one of the most destructive pests of mango throughout the country. The eggs are dull white and concealed inside tissue. The colour of the nymphs vary from dust yellow to pale yellow and these nymphs walk in a crab like manner. The adults are small wedge shaped grayish insects measuring3.4-5.1mm in length. Amritodus atkinsoni is comparatively bigger and light brown in colour with two spots on scutellum, while Idioscopus clypealis is smallest and lighter in colour with dark spots

Mango Fruit fly : Bactrocera dorsalis : Tephritidae

This is probably the most economically important pest of mango. It can attack many crops like mango, guava, peach, apricot, cherry, pear, ber, citrus, banana, papaya, avocado, passion fruit, coffee, melons, jack fruit and strawberry. There are also related species that may cross infect. The adults are light brown small flies with a single pair of membranous transparent wings. The other pair is modified into halteres. Eggs are thrust into the skin of the mangoes when they are semi ripe. A drop of resin comes out of the ovipunctures and can be seen as a black mark. While purchasing mango, this can be used as an indication of the presence of the fruit fly eggs.

Garcinia mangostana Linn. (GML) belongs to the family of Guttiferae and is named “the queen of fruits”. It is cultivated in the tropical rainforest of some Southeast Asian nations like Indonesia, Malaysia, Sri Lanka, Philippines, and Thailand. The mangosteen fruit is round in shape, dark-purple, 2 to 3 inches in diameter and contains 4 to 8 segments of snow-white, delicious soft flesh. The fruit may or may not contain seeds. Encasing the flesh is a purple skin 6 to 10 cm thick. Because of its taste and medicinal properties, the mangosteen is often called “The Queen of Fruits”. For centuries, the mangosteen has been honored and cherished by the peoples of Southeast Asia. It is a delicately flavoured fruit of temperate zone.

Mangosteen is native to Malaya Peninsula, and mainly cultivated in Malaysia, Indonesia, Thailand, Sri Lanka, Myanmar, India, Vietnam, Philippines, China, California (USA), Hondurus, Panama, Hawaii, Trinidad and Cuba. In India it is cultivated in lower slopes of Nilgiris, Kerala and West Bengal.

Uses

Mangosteen is mainly used as a fresh fruit. Aril of the seed is edible after being boiled in water. The cortex of the fruit contain tannin, and is used as a commercial dye. The rind of fruit is astringent, which is used in chronic dysentery and diarrhea. The bark and young leaves are used to gargle for sore throat. It contains a crystalizable substance known is mangosteen.

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:

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).

In the coffee family Rubiaceae, Rubia cordifolia L. (RC) is a useful medicinal plant in the Ayurvedic system due to its many pharmacological characteristics. It is also known as common Madder or Indian Madder. It was grown for a red pigment generated from the roots. Rubia was divided into roughly 70 species that were found all over the world, including 36 species and two variants described from China. Because of their high bioactivities, Rubia plant extracts and phytochemicals have gotten a lot of interest.

Morphological characteristics

It is a perennial, prickly climber with a stem, growing up to 12 m long. Leaves are highly variable, ovate lanceolate, 5-7 nerved, 2-10 cm long and 2-5 cm broad, occurring in whorls of 4-6. The stems are slender and quadrangular. The leaves are simple, opposite and stipulate, the stipule is interpetiolar. The petiole is 1.5–3 cm long. The blade is lanceolate, 1.5–5 cm × 0.5–2.5 cm, cordate at base, obtuse acuminate at apex and displays three to five longitudinal nerves. Roots are perennial, long, cylindrical, and rusty brown in colour

1) Botrytis Gray Mould
Diagnostic Symptoms
• Appearance of a gray, fuzzy mold leaves, stems and on flowers of or plants. Also called, “gray mold”.
• Spotting or blight on leaf and flower stem lesions, and dieback.
• Flower parts become necrotic and die(Fig-1).
Etiology
Domain : Eukaryota
Kingdom : Fungi
Division : Ascomycota
Class : Leotiomycetes
Order : Helotiales
Family : Sclerotiniaceae
 

Marigold is one of the dominant loose flower crops in India, particularly important for religious ceremonies, festivals, weddings, garlands and decoration. The principal cultivated types include African marigold (Tagetes erecta) and French marigold (Tagetes patula). The chapter discusses the origin, distribution, genetics, botanical characteristics and important varieties of marigold. It also highlights emerging applications such as lutein extraction, natural colourants, culinary uses and companion planting. Detailed production practices cover climate, soil, propagation, nursery management, land preparation, nutrient management, planting, irrigation, pinching and flower harvesting. Important pests and diseases, postharvest handling and yield are also discussed for efficient commercial production.

Bud caterpillars : Helicoverpa armigera : Noctuidae

Eggs are laid singly on young buds.  Larvae feed on developing flowers by damaging florets. They can also eat the leaves.

Leaf webber : Phycita sp. : Phycitidae

Larvae of Phycita sp. feed on heads of buds and flowers.

25.1 Introduction

The method of selection in which a gene/QTL (Quantitative Trait Locus) is selected on the basis of the genotype of the molecular marker (also called DNA marker) linked to this gene/QTL is known as marker-assisted selection (also called marker-aided selection). The idea of marker-assisted selection (MAS) was first advocated by Tanksley (1983). MAS can be used in combination with the conventional breeding methods or novel breeding schemes could be devised to take full advantage of the marker data. MAS has been widely used for introgression of the desired genes and QTLs using backcross programmes.

25.2 Marker-Assisted Backcrossing (MABC)

The backcross programme based on molecular marker is usually called marker-assisted backcrossing (MABC). MABC has three activities: (a) foreground selection, (b) background selection and (c) recombinant selection.

25.2.1 Foreground Selection

The use of molecular marker to select the gene/QTL being introgressed is known as foreground selection. The objective of foreground selection is to select the target gene, i.e., the gene being introgressed, without phenotypic evaluation for the trait governed by the target gene. Foreground selection for a gene/QTL will be highly desirable in a variety of situation, some of which are listed below:

ABSTRACT

In last twenty years, molecular biology has revolutionized conventional plant breeding techniques in many areas. The use of molecular markers in conventional breeding techniques has also improved the accuracy of selection and allowed breeders to produce varieties with combined traits that were difficult before the advent of DNA technology. Among vegetables, onion (Allium cepa L.) is the most important cash crop of India. Onion productivity in India is much lower (11.38 tones / ha.) compared to other countries (44.1 tones / ha. in Japan). Purple blotch disease (PBD) caused by Alternaria porri (Ellis) Ciferri decreases the yields by up to 50 percent. Genetically resistant onion varieties are the most economical, simple and eco-friendly mode of disease management. The advent of mo- lecular markers provided the opportunity to understand the genetic resistance more pre- cisely. In this paper we present our successful efforts in developing PCR based markers linked to purple blotch disease resistance, so that such markers can be easily integrated into PBD resistance breeding program in onion. Onion germplasm was screened for PBD resistance. Line PBR 287 was identified as a good source of resistance and the genetics of inheritance of resistance in this line was worked out. The protocols for isolating good quality DNA and PCR amplification conditions were standardized. 37 polymorphic mark- ers were identified between resistant and susceptible parents. Crosses were made between resistant and susceptible parents. Parents, F₂ and individual F₂ progenies were subjected for analysis of genetics of resistance and RAPD marker analysis. F₂ individuals segregated in 3:1 ratio for resistance. DNA from resistant and susceptible F₂ individuals was pooled separately for Bulked Segregant Analysis (BSA). BSA identified one RAPD marker of 900bp being linked to resistance. Further Chi-square test for detecting the deviation of segregation of this 900bp marker confirmed segregation with classical Mendalian ratio 3:1 for a monogenic trait. Identified marker is of great practical utility to the plant breeders to screen large number of populations for purple blotch disease resistance at the early stages of the crop even in absence of the pathogen.

A concentrated, hydrophobic liquid containing volatile aroma compounds obtained from aromatic plants is referred to as essential oil. It is so-called to indicate that the oil is the fragrant essence of the plant from which it is extracted generally through various distillation methods. The economics working behind essential oils has three components. First, the cultivation of herbs and plants used to extract essential oils; second, the actual process of extraction of the oils; and, third, the marketing and actual sale of these oils. But the major emphasis is often given to the agrotechnology, since the crop yield and yield of the essential oil depends on the quality of cultivation. The cost of cultivation of herbs in the developing countries per hectare is estimated at US $ 600 to 1100. This cost mainly comprises labour cost and as such this industry is uniquely suitable only for developing nations. The revenue from essential oils after the extraction per hectare is estimated to be around US $ 2500 to US $ 6500. According to industry sources, more than 3,500 essential oils are known. Out of these, some 400 are used for commercial purposes on a regular basis. These are obtained mostly from agricultural plants, some from wild plants that may be seasonal or perennial. Oil can be extracted from any part of plants—from leaves, flowers, fruits, roots etc. Whatever the source of essential oils, they have complex compositions, containing alcohol, aldehydes, ketones, phenols, esters, ethers and turpenes in varying proportions.

Demand and Supply of Horticulture Produce

India’s horticulture production rose 30 per cent in the last five years — an impressive rise, considering growth in the preceding five years stood at about 23 per cent. India is currently producing 257.2 million tonnes of horticulture produce from an area of 23 million ha.The area under horticulture grew by about 3.8% per annum but production rose by 7.6% per annum. Improvement in productivity of horticultural crops was noted by about 28% between 2001-02 and 2011-12. Of the 140 million farmers in the country, horticulture engages about 20 million and also contributes about 30 per cent of India’s agricultural GDP. Horticulture contributes 37% of total exports of Agricultural commodities. India is among the foremost countries in horticulture production, just behind China.

The world trade in flavour and fragrances in 1987 was US $ 7,000 million and at present, it is estimated at more than $ 10,000 million annually. In 1975, perfume was used by one woman in ten, but today it is used by eight out of ten women; even reticent Japanese women are adopting the habit (Anonymous, 1995 c). The average annual industry growth rate in perfumes of India is valued at about US $ 20 million with an annual growth rate of 12% (Murty, 1993),while the UK market is Rs. 2000 crores and the US market supersedes it by Rs. 4000 crores (Walia, 1997). However, the domestic luxury perfume market is estimated to grow at a rate of 20-25 % (Biswas, 2012). Besides domestic market, India earns a lot of foreign exchange from the export of total essential oils and perfumes and is fast growing as it is showed from the trends in export earnings of Rs. 11.1 corers in 1982-83 rose to 4-fold in 1986-87 of Rs. 41.1 crores (CHEMEXCIL, 1988). According to a market survey report, Ahmed (1999) reported that the daily turn over of the attar market in India is more than 50 crores.

Middle East countries continue to be the big buyers of our traditional perfumes. Kewda flavour which is used in pan masala and tobacco is a familiar one in this part of the world. Kewda essence, being one of the few flavouring oils, has a good scope for export to other developed countries where the food flavouring industry is well developed. India is the leading producer of kewda perfumes in the world and the market for kewda perfumes is fast expanding specifically in the Arab countries. India exported the kewda water of Rs. 266.2 lakhs in 1986-87 which rose to Rs. 276.4 lakhs in 1987-88 (CHEMEXCIL, 1990). Anonymous (2007) reported that about 140 distilleries (bhattis), both local and outsider, earn about Rs.1.3 crore by way of extraction charges and annually they extract 332 kgs of kewda oil (Rs.8.3 crore), 7823 kgs of kewda attar (Rs.15.65 crores) and 150 MTs of kewda water (Rs.4.47 crore), the total coming to around Rs.28 crore. For extracting attar , the extractors use about Rs. 8 crore worth of sandal wood oil procured mainly from other states, while Rs.18 crore goes to the plantation owners as flower cost and to the flower collectors.

Raw cashew nuts are a seasonal commodity and the trading season is from March to May. Growers usually supply the primary or village markets where small traders collect and supply the urban markets. The cashew trade is seldom handled by exclusive traders. Usually, those traders who collect other plantation products also trade in cashew. Due to the highly competitive nature of the cashew trade, growers have few marketing problems. When large quantities are collected by middlemen, the processors enter the marketing chain and make wholesale purchases. Grades and standards for cashew are yet to be introduced in India. Quality is generally determined by appearance and cutting tests that traders employ prior to purchase. The raw cashew nut market involves a large amount of capital where nearly 80 per cent of the produce is transacted within a period of 35 days. The current value of Indian production is estimated at around Rs. 10,000 million. This capital is made available by industry for procurement and processing operations.

There are no growers’ cooperatives or organizations for cashew marketing. In Kerala, however, the government has been involved in the procurement process and supply to large-scale processors. This adversely affected the cashew trade and has now been replaced by a free market policy.

In addition to the local production of nearly 7 lakh tonnes, India also imports a considerable quantity of raw nuts from several African and South-east Asian countries to satisfy the national processing capacity of about 12-14 lakh tonnes established in the country.