eChapters

1. Introduction
Hydrogenation plays a vital role in the transformation of organic compounds, making it essential for synthesizing fine chemicals and pharmaceuticals. This process is widely utilized in both laboratories and for industrial applications (Andersson et al., 2008). Typically, two approaches are used for hydrogenation: traditional one involves direct hydrogenation using pressurized hydrogen gas, and the other relies on transfer hydrogenation (TH), which involves addition of hydrogen into a molecule from a non-H2 sources (Johnstone et al., 1985). The use of high-pressure hydrogen gas, however, demands significant investment in infrastructure, making it less economically feasible for developing a sustainable hydrogenation industry. In contrast, TH has gained increasing attention due to its sustainability, particularly when employing hydrogen donors derived from biomass, such as alcohols and organic acids, which are abundant, cost-effective, and easy to handle instead of using non-renewable H2 gas for reduction of CO2 (Becattini et al., 2021) (Figure 1).
2. Historical Background and Classification
The hydrogen transfer process has a rich history spanning over a century. In 1903, Knoevenagel first demonstrated that palladium black effectively promoted the disproportionation of dimethyl 1,4-dihydroterephthalate into dimethyl terephthalate and cis-hexahydroterephthalate, in which hydrogen transfer was occurred between identical molecules (identical donor and acceptor) (Knoevenagel et al., 1905). This pioneering work established the foundation for hydrogen transfer reactions. Braude and Linstead later categorized these reactions into three distinct types (Braude et al., 1954):

Introduction 
Schiff base ligands (also called azomethines) were first revealed by German chemist Hugo Schiff in 1864. They are synthesized through a straightforward condensation reaction between an amine and a carbonyl compound (aldehyde or ketone). This reaction forms a characteristic imine group (>C=N-) while eliminating a water molecule as a byproduct. Schiff bases are highly versatile and serve as ligands for various transition metals, forming complexes with applications in catalysis, material science, and medicinal chemistry. Their ease of synthesis, tunable structure, and ability to stabilize metal centers make them valuable in both academic research and industrial processes (Cozzi, 2004). They can form stable complexes with almost all metal ions, offering various coordination geometries. Their flexibility makes them valuable in catalysis, medicinal chemistry, and materials science, with wide applications across these fields. Schiff base metal complexes exhibit exceptional catalytic performance in various high-temperature reactions (>100 °C), even under humid conditions. These complexes are widely employed in catalytic processes, such as oxidation, reduction, carbon-carbon bond formation, polymerization, and asymmetric synthesis (Zoubi et al., 2016). Recently, interest in olefin polymerization has increased due to their ability to catalyze the formation of commercially significant branched and linear polyethylenes. Their versatility, structural tunability, and high stability make them ideal for such applications, offering pathways to develop advanced materials with tailored properties for industrial and commercial use. Schiff base complexes thus remain central to modern catalysis research. These complexes have shown great potential in producing polymers with tailored properties, making them highly valuable in industrial applications. Schiff base complexes have gained attention for their catalytic roles, particularly in the reduction of ketones to alcohols and the alkylation of allylic substrates. These complexes, typically coordinating with metal ions, facilitate crucial organic transformations by stabilizing intermediates, offering an efficient and selective route for various chemical reactions. Schiff base complexes enable controlled ring-opening polymerization of cycloalkenes at low temperatures, offering precise molecular weight regulation without side reactions. In contrast, traditional catalysts like tungsten, molybdenum, or ruthenium with alkylating agents require high temperatures and lack molecular weight control, making Schiff bases more efficient for polymerization. The oxidation of hydrocarbons catalyzed by Schiff base complexes has garnered significant academic and industrial interest. These metal complexes are studied for their ability to facilitate efficient and selective oxidation reactions, offering insight into their catalytic activity and potential applications in chemical processes and industrial oxidation technologies. The ring-opening of large cycloalkanes is challenging due to their stability, but Schiff base complexes of cobalt(II) and chromium(III) effectively catalyze these reactions. These complexes enhance metal center reactivity and stabilize intermediates, enabling efficient cleavage of cyclic structures and expanding possibilities for catalytic transformations in synthetic and industrial chemistry. These complexes not only facilitate the process but also exhibit important enantioselectivity, creating them valuable catalysts in asymmetric synthesis and fine chemical production. Chiral Schiff base complexes have emerged as versatile and efficient catalysts in various organic transformations, particularly in asymmetric synthesis. Schiff bases derived from salen and binaphthyl frameworks are effective in Michael addition reactions, offering high enantioselectivity and catalytic efficiency. While transition metal complexes

1. Introduction
Palladium (Pd), which has the atomic number 46, was discovered in 1803 by the English chemist William Hyde Wollaston. It is a well-known transition metal recognized for its versatile catalytic properties in chemical reactions, material sciences, and various industries. The palladium-catalyzed coupling reactions extend beyond the formation of biaryls. Many carbon–carbon, carbon–nitrogen, and carbon–oxygen bond-forming reactions in organic chemistry are facilitated by palladium salts and catalytic systems derived from palladium. Some notable organic reactions that involve palladium include the Mizoroki-Heck reaction, (Biffis et al., 2018, Koranne et al., 2023, Lee et al., 2021) Suzuki-Miyaura coupling, (Zhang et al., 2023) Negishi reaction, (Haas et al., 2016). Stille coupling, (Cordovilla et al., 2015). Sonogashira coupling, (Chinchilla & Najera, 2007) Tsuji-Trost reactions, (Kvasovs et al., 2023). and Wacker catalytic processes. (Zhang et al., 2023) In this chapter, we will focus on the applications of palladium and its salts in C-N bond-forming reactions.
2. Palladium (Pd)-Catalyzed C–N Bond Formation
Besides copper, palladium metal is considered as the most widely used metal in organic synthesis. The discovery of cross-coupling reactions catalyzed by palladium(0) complexes in the 1970s was a highly important achievement that substantially changed the strategy of organic chemistry. Best applications of the palladium salts are in enantiolective and new C-N bond forming reactions. Stephen L. Buchwald and John F. Hartwig opened up the catalytic scope of palladium in newer methodologies on C–N bond forming reactions during 1990s, (Ruiz- Castillo & Buchwald, 2016) and henceforth, new methodologies of carbocycles, heterocycles, and simple organic compounds have been created in large scales (Rayadurgam et al., 2021). The mechanisms of palladium-catalyzed C-N cross-coupling reactions are critically discussed in numerous high-quality research journals with different theoretical and experimentally proven methods (Beletskaya & Averin, 2021). However, the most acceptable mechanistic pathway to reaction products in these Pd-catalyzed reactions involving palladium is illustrated in Scheme 1. The process begins with the formation of a palladium complex through the reaction of an aryl halide (which can be aliphatic, heteroaryl, or functionalized alkenes/alkynes), a palladium salt, and amino nucleophiles. In the presence of a suitable base, the loosely bonded halide or any leaving groups are eliminated, leading to the formation of a palladium (IV) complex. This complex then undergoes reductive elimination, resulting in stable aminated aryl, heteroaryl, alkyl, or functionalized alkenes/ alkynes. Additionally, a more generalized reaction mechanism is presented in a circular pathway format, highlighting the bonding approaches, rearrangements, intermediate formations, and the final release of target compounds, as depicted in Scheme 1. The involvement of higher valence organo-palladium complexes in such catalytic transformations have been well established (Hickman & Sanford, 2012).

1. Introduction
With commercial uses ranging from the production of high-quality substances to the manufacture of pharmaceuticals, hydrogenation is an essential step in the formation of organic compounds (Cerveny et al., 1986). There are two main approaches to hydrogenation: direct hydrogenation, which employs pressurized hydrogen gas, and transfer hydrogenation (TH). A versatile and effective approach for producing a large variety of hydrogenated molecules, the TH method entails adding H2 to molecules via an origin other than H2 gas. This approach is increasingly preferred over direct hydrogenation and has recently attracted considerable interest in hydrogenation research. The benefits of the TH method include (i) the elimination of potentially dangerous pressurized hydrogen gas and the complexity of experimental setups, (ii) the accessibility, cost-effectiveness, and ease of use of hydrogen donors, (iii) the potential to recycle the main byproduct, and (iv) the availability and stability of the catalysts employed (Brieger et al., 1974).
1.1. The Historical Context, Core Principles, and Groundbreaking Research on TH (transfer hydrogenation)
With a history spanning more than a century, the TH reaction has a rich past. In order to enable hydrogen transfer between equivalent donor and acceptor units, Knoevenagel showed in 1903 that palladium black could efficiently aid in the disproportionation of dimethyl 1,4-dihydro terephthalate into dimethyl terephthalate and cis-hexahydroterephthalate. Three primary types of hydrogen transfer reactions were distinguished by Braude and Linstead: (i) the hydrogen movement within a single molecule; (ii) hydrogen disproportionation, which entails transfer among identical donor and acceptor units; and (iii) TH-dehydrogenation, which takes place between distinct donor and acceptor units. Of them, THdehydrogenation— often just called TH—is the most well-known and often applied sector. Meerwein-Ponndorf-Verley (MPV) reductions, early transition metal-catalyzed reactions, organocatalytic processes, enzyme-catalyzed reactions, heat techniques, and base-catalyzed reactions are among the types of TH reactions that are classified according to the type of catalyst used. The historical context, important research, and underlying ideas of each category will be covered in detail in this section.In 1925, Meerwein et al. independently reported the significant MPV reduction, which were the first TH process involving carbonyl groups. After earning his Ph.D. under Richard Anschütz in Bonn, where he was appointed a professor in 1914, Hans Meerwein (1879–1965) moved to Königsberg in 1922 and then to Marburg. His name is associated with a number of processes and reagents,

Introduction
Metal-catalyzed C–N cross-coupling reactions are powerful synthetic methods for producing both simple and complex organic compounds, including natural products. These methodologies typically involve shorter reaction times and can achieve good to excellent yields with a broad range of reactions, exhibiting high regioselectivity in certain cases. The coupling of carbon and nitrogen to create organic compounds that contain nitrogen, such as urea and amides, is one of the most fundamental chemical reactions and plays a crucial role in human civilization. C–N coupling reactions have significant importance in industry, starting with the production of ammonia (NH3) through the Haber–Bosch process. Molecules containing C–N bonds are prevalent in a variety of organic materials, natural products, pharmaceutical compounds, and agricultural chemicals. This wide applicability makes them crucial chemicals, leading synthetic organic chemists to continuously seek out novel synthetic methods. In recent years, numerous synthetic strategies involving either transition metals or metal-free enzymes and biocatalysts have emerged. Additionally, new technologies, such as electroreduction, have been employed in these C–N coupling processes (Bariwal & Van der Eycken, 2013, Li et al., 2022, Yin et al., 2024, Rahman et al., 2022).
Common copper salts/complexes, and diamino ligands
Copper is commonly found coordinated by two, three, or four ligands, resulting in linear, trigonal planar, or tetrahedral geometries. Well-known and inexpensive copper halides, such as copper (II) glycinate, copper (II) acetylacetonate (particularly CuI), copper acetates, copper oxide, copper sulfate, and copper triflate salts, are widely used as catalytic systems in C–N bond-forming reactions. Additionally, other complexes such as Cu di-isopropyl salicylate (CuDIPS), copper phthalocyanine, and copper aspirinates have also been employed in these reactions. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions are well-established methods for forming triazoles via C–N bonds in one pot. These reactions often involve domino click chemistry and green approach methodologies, leading to the synthesis of biologically important triazoles. Copper salts in combination with diamine ligands are widely used in C–N bond-forming reactions through cross-coupling strategies. Some notable examples of such diamino compounds that can coordinate with copper are illustrated in Figure 1.

Introduction 
Over the past few decades, magnetic nanoparticles (MNPs) have been showing great importance in the field of organic synthetic reactions, catalysis, sensors, biomedicines, environment rehabilitation, etc. (Gawande, M. B. et al., 2013; Del Rio, M. et al., 2022). Numerous research teams have recognized the significance of solid support materials for the creation of environmentally acceptable nano catalysts with high catalytic activity in light of the infinite advantages of MNPs (Sharma, R. K. et al., 2016; Gawande, M. B. et al., 2013; Deng, J. et al., 2011; Nasrollahzadeh, M. et al., 2015; Hudson, R. et al., 2014; Payra, S. et al., 2017; Chng, L. L. et al., 2013; Parandhaman, T. et al., 2017; Zhang, F. et al., 2014; Pourjavadi, A. et al., 2012). Heterogeneous catalysts in organic chemistry are solid catalysts that, while remaining in a distinct phase (usually solid) from the reactants (generally liquids or gasses), promote chemical reactions without being consumed in the process. These catalysts, which have multiple benefits such as ease of separation, recyclability, and selective reactivity, are essential in a variety of industrial processes and laboratory reactions (Lattuada, M. et al., 2007; Jiang, K. et al., 2011). The standard formula for ferrite nanoparticles is MFe2O4, where M is usually divalent metal ion like copper (Cu), zinc (Zn), or nickel (Ni), and iron (Fe) is the common metal (Kazemi, M. et al., 2018). These nanoparticles work very well as heterogeneous catalysts in a variety of chemical reactions because of their special magnetic and electrical characteristics.Because of its special qualities as a catalyst in a variety of processes, copper ferrite (CuFeO4), a mixed-metal oxide, has drawn interest in organic chemistry (Kharisov, B. I. et al., 2019; Zhu, J. et al., 2014; Vannucci, A. K. et al., 2012). It is a spinel-type ferrite that can catalyse a variety of organic transformations because it combines iron and copper in a stable, highly active structure. With benefits including high stability, reusability, and low toxicity, these catalysts are frequently employed in processes like oxidation, coupling, and reduction (Taghavi Fardood, S. et al., 2018). The Figure 1 represents schematic diagram of a reaction where the ferrite nanoparticles as catalyst have been recovered with the aid of an external magnet after the formation of reaction product.

Introduction 
Natural product scaffolds and heterocyclic ring-based organic compounds are crucial for developing bioactive substances and therapeutic drugs, serving as essential structural units for bioactive molecules and pharmacophores. Numerous experts have worked hard to design and develop organic synthesis, which could make it easier to obtain these crucial organic chemicals. Due to the multistep reactions involving several hazardous chemicals, conventional organic synthesis is neither commercially feasible nor environmentally benign. To overcome these issues, improvisation or developing a new synthetic approach with a superior atom and step economic procedure is always desirable. The biggest challenge in organic synthesis is functionalizing a carbon-hydrogen (C-H) bond in a molecule. This is generally achieved through radical intermediates and catalysis by enzymes or transition metals. The transition metal-catalyzed process is the most popular due to its high chemoselectivity, site-selectivity, and efficiency (Yamaguchi et al., 2012). Inert C-H bonds can be directly functionalized, offering appealing synthetic strategies that enhance both atom and step economy and provide an overall efficiency of multistep synthetic sequences, leading to a sustainable and greener approach. These optimizations provide atom and step-economical methods for synthesizing structurally complicated organic molecules with broad substrate scope and good to exceptional product yields (Ackermann, 2011; Gensch et al., 2016). Direct conversion from the substrate to the desired organic compound without pre-functionalization is attractive and cost-effective. However, it can be quite challenging to selectively functionalize particular C-H bonds due to the inertness of those C-H bonds having similar electronic and bonding properties and the ubiquity of C-H bonds in organic molecules (Sambiagio et al., 2018). Two main techniques have been explored to obtain selectivity in C-H bond functionalization (Brückl et al., 2012). The first is based only on the natural reactivity pattern of an organic molecule. This strategy is highly successful for some heterocycles with at least one specific reactive site due to the presence of heteroatoms. However, it produces inadequate selectivity for most aliphatic and aromatic hydrocarbons. The latter is to direct further functionalization at a particular site using directing groups already present in the molecule (Kuhl et al., 2012). The development of directing groups that effectively control the regioselectivity of C-H functionalization has lately transformed this field, enabling the incorporation of desired groups in unfunctionalized sites (Docherty et al., 2023; Labinger & Bercaw, 2002). Employing directing groups, various functional groups are added to a molecule using this method. Directing groups are crucial for breaking a C-H bond in a transition metal catalysis reaction, where the metal center in the active catalyst complex is usually coordinated with the substrate through a weak interaction with the nearby C-H bond. This interaction is typically not selective; thus, the metal centre may activate numerous C-H bonds on the substrate. However, when a directing group is incorporated into a substrate, the metal center can interact more strongly and regioselectively with a specific region on the substrate as directed by the directing group. This causes selective cleavage

1. Introduction
Pharmacognosy, formerly known as materia medica, is the study of unrefined medications derived from minerals, plants, and animals. Although C. A. Seydler coined the phrase in 1815, J. A. Schmidt used it in 1811 to refer to the study of medicinal plants and their characteristics. The word refers to the study or knowledge of medicines and is derived from the Latin terms gignoso, which means “to acquire knowledge of,” and pharmakon, which means “a drug.” Plants, animals, or their parts that have just been dried, sliced longitudinally or transversely, or infrequently peeled after collecting are considered crude pharmaceuticals. The majority of the basic drugs used in medicine are derived from plants, with only a minor portion coming from the animal and mineral kingdoms. Drugs made from plants are full plants, however cinchona bark, ginger rhizome, nux vomica seeds, and senna leaves and pods are plant components. Some medications, such as orange and lemon peels and colchicum corm, are used fresh, but the majority are dried after harvesting. Crude pharmaceuticals can also be obtained by straightforward physical processes like drying or water extraction. Aloe is the dried juice of Aloe species’ leaves, opium is the dried latex from poppy capsules, and black catechu is the dried aqueous extract from Acacia catechu’s wood. Plant exudates such as gums, resins, balsams, volatile oils, and fixed oils are also considered crude medicines. Additional drugs that physicians, surgeons, or pharmacists use directly or indirectly include diatomite for filtering gums or turbid liquids; cotton, silk, jute, and nylon for surgical dressings or kaolin; wax, gelatin, and agar for use as pharmaceutical auxiliaries of flavoring or sweetening agents; and drugs used as insecticides or vehicles. Animal medications can be extracts, like liver extracts, glandular products, such thyroid organs, or whole animals, like can-tharides. Similarly, goods that come from animals include fish liver oils, bee wax, musk, certain hormones, enzymes, and antitoxins. Drugs can be classified as either organized or disorganized. Organized medications come directly from plants and are composed of biological tissues. Unorganized pharmaceuticals are generated by physical intermediary procedures such as cutting, drying, or extraction with water, and although being derived from plants, they do not contain cellular tissue. Thus, unstructured medications include gums, resins, aloe, catechu, opium, and other plant exudates. Kaolin, chalk, diatomite, and other Ayurvedic bhasmas are examples of mineralbased medicines.

1. Introduction Plants naturally contain compounds called phytochemicals. Due to their numerous therapeutic applications, these phytochemicals are becoming more and more well-known these days. Phytochemicals are essential in the fight against a variety of illnesses, including cancer, arthritis, and asthma. These phytochemicals have no side effects like pharmaceutical compounds do. Because the phytochemicals treat illnesses without harming people, they can also be referred to as “man-friendly medicines.” The primary topics of this study are phytochemical collection, extraction, and qualitative and quantitative analysis. In order to protect themselves against herbivores, many plants secrete chemical substances. Examples of therapeutic plants that include the main groups of pharmacologically active phytochemicals are provided below. Weeds that contain phytochemicals, like chickweed, dandelion, and nettle, are frequently found surrounding human settlements. Many phytochemicals, including curcumin, epigallocatechin gallate, genistein, and resveratrol are pan-assay interference compounds and are not useful in drug discovery.

1. Definition and Scope Pharmacognosy is the study of drugs and other economically valuable materials derived from natural sources, encompassing both plant and animal origins. This field examines a wide spectrum of aspects related to these materials, including their history, production, commerce, collection, selection, identification, valuation, preservation, and ultimately, their use. The term “pharmacognosy” was first formally used by C. A. Seydler in his 1815 dissertation, Analecta pharmacognostica. The word itself is derived from the Greek terms pharmakon, meaning drug or medicine, and gnosis, meaning knowledge. Thus, pharmacognosy literally translates to “knowledge of drugs.” It’s crucial to differentiate pharmacognosy from pharmacology due to their distinct areas of focus within the realm of drugs. Pharmacology, aptly defined as “a discourse on drugs,” centers on investigating the effects of drugs and other chemical substances on living systems, be it organs or entire organisms. In contrast, pharmacognosy directs its attention to the origins, identification, and inherent properties of natural products – often from plants, but also including other biological sources – that exhibit potential medicinal or economic significance. Pharmacognosy, by its very nature, is an interdisciplinary science, integrating knowledge from a variety of scientific domains. A strong foundation in botany is fundamental for the accurate identification and classification of medicinal plants. Chemistry is indispensable for elucidating the chemical constituents of these natural products and understanding their characteristics. Zoology provides insights into drugs and materials derived from the animal kingdom. Moreover, the principles of physics and genetics are applied to tackle diverse issues concerning the identity, purity, quality control, and effective preservation of these important natural resources.

For millennia, humans have forged an intimate relationship with the natural world, recognizing and harnessing the therapeutic potential of plants for healing. This unit, “Introduction to Herbal Medicines,” embarks on a comprehensive exploration of plant-based therapies, delving into their historical evolution, fundamental terminology, integration within traditional healing systems, and the practical aspects of their cultivation, processing, and utilization. We aim to provide a solid bedrock of knowledge, enabling a deeper understanding of the science and practice of herbal medicine, and appreciating its enduring significance in the modern world."
1. History and Scope of Herbal Medicines
1.1 Ancient Beginnings: The Dawn of Plant-Based Healing
• Paleolithic Roots: Our most ancient ancestors, from the Paleolithic period, are believed to have harbored a refined comprehension of the pharmacological attributes of vegetation. Excavations have unearthed indications of specific plant utilization for addressing physical trauma and maladies, underscoring an early grasp of their remedial efficacy. This knowledge was likely passed down through oral traditions, forming the foundation of future herbal practices.
• Civilizational Emergence: With the rise of civilizations, medicinal plant use became more structured and recorded. In ancient Sumeria, clay tablets inscribed with cuneiform script, dating back to 3000 BC, record the use of various plants for medicinal purposes, showcasing organized knowledge of herbal remedies. The Egyptian Ebers Papyrus (c. 1550 BC), a remarkable medical text, provides detailed prescriptions for treating a wide array of ailments using plants like aloe vera, garlic, and opium, evidencing a sophisticated understanding of pharmacotherapy. In India, the ancient system of Ayurveda, with its foundational texts, the Charaka Samhita and Sushruta Samhita, meticulously documents the use of numerous medicinal plants, emphasizing a holistic approach to health. Similarly, Traditional Chinese Medicine (TCM), with the Shennong Bencao Jing (c. 1st century AD), provides a comprehensive pharmacopeia, demonstrating the profound integration of herbal remedies into Chinese medical practice.

1. MATURITY INDICES
Maturity indices (right time of harvesting) are quality factors that give clues as to when a product should be harvested to allow marketing flexibility and ensure the attainment of minimum acceptable quality to the user. It also refers to the set of criteria used to determine the stage of maturity for harvesting the horticultural crops. Commodities harvested either pre-mature or too late are more susceptible to postharvest physiological disorders, diseases and have poor shelf life than harvested at right stage of maturity. The pickers/ handlers are trained in methods of identifying produce that is ready for harvest. However, optimum harvesting stages depends upon type of produce and their final use. Horticultural crops may be harvested at two main maturity levels i.e., physiological maturity and commercial or horticultural maturity. Therefore, the proper stage/maturity indices for harvesting of all horticultural crops should be identified for their implementation during harvesting. Horticultural maturity in relation to developmental stages of the plants is depicted in Fig 3.1.
Maturity indices are different for different horticultural crops and are employed to:
1. Ensure sensory quality (flavour, colour, aroma, and texture) and nutritional quality: Harvesting horticultural produce too early (under-developed or immature produce) will result

I. INTRODUCTION
The fruits and vegetables we eat and flowers and ornamentals we enjoy are biological entities. They breath, produce heat, perspire, are easily damaged, get diseases and finally die. These carry on processes characteristics of all living things before or after harvest to perform the metabolic activities:
1. to maintain cellular organization
2. to transport metabolites around the tissue and
3. to maintain membrane permeability.
The job of postharvest technologist is to understand life in fruits, vegetables and flowers and prolong their life as much as possible. The post harvest life of produce depends on the rate at which they use up their stored food reserves and their rate of water loss. The sugar and starches (carbohydrate derivatives) are stored in various parts of plants through a process known as photosynthesis occurring in growing plants and are used later to provide energy for further growth, development and to prolong post-harvest life. The process of photosynthesis in growing plants and respiration in harvested produce can be seen in Fig. 2.1. The released energy through process known as respiration occurs in plants before and after harvest. Thus, principal normal physiological processes leading to aging are respiration and transpiration.

I. INTRODUCTION
Horticultural crops include fruits, vegetables, flowers, plantation crops, spices, and medicinal and aromatic plants have emerged as a major economic activity in India. It contributes 30% GDP from 11.73 % of its arable land area. Horticulture crops cover over 23.4 million hectares of area, which is approximately 12.7% of the total gross cropped area of the country and contributes 18-20% of the gross value of India’s agricultural output (NHB, 2013). India is the world’s second largest fruit and vegetable producing country accounting for 77.7 million metric tonnes of fruit and 159.5m M tonnes of vegetables (NHB, 2013). Besides, about 5.66 million tonnes of loose flowers, spices, mushroom and aromatic plants are also produced. The country produces 41% of world mangoes, 23% banana, 24% cashew nut, 36% green peas, 10% onion and 30% cauliflower and accounts for 12% of world fruit and 13.25% of vegetable production (NHB, 2013). Owing to wide diversity of agro climatic conditions, almost all types of temperate (apple, peach, plum, apricot, cherries and nuts), subtropical (mango, guava, papaya, etc), tropical (banana, pineapple etc), arid fruit (ber and aonla), plantation crops (coconut, cashewnut and arecanut) and diverse variety of vegetables are grown in India. The export of fresh fruit and vegetables from India in 2006-07 was estimated at 9.84 Lakh tonnes valued at Rs 2411.70 crores. Mango, grapes, apple, onion, potato, green vegetables like okra, bitter gourd and green chillies were the major items of export. Similarly, India exported 5.97 Lakh tonnes of processed foods comprising of mango pulp, juices, concentrates, dried and processed vegetables, pickle and chutney, alcoholic and non-alcoholic beverages worth Rs 2818.1 crores (APEDA, 2012) (Table 1 to 3).

Coffee is grown at higher elevation across the Western Ghats between 750 and 1200 m amsl. It requires a certain degree of shade for its better performance.  The annual rainfall over the coffee growing tracts varies between 1400 and 2600mm, having uni/bi-model rainfall with prolonged dryspell from November to May. It is more so over North of the Western Ghats. The mean annual maximum temperature varies between 24 and 300C while the minimum between 15 and 180C. The difference between maximum and minimum temperatures (temperature range) varies between 5 and 160C across the coffee tract. The ‘Monsooned Malabar Coffee’ is a specialty coffee produced from the erstwhile ‘Malabar Region’. It undergoes certain changes in physical and biochemical characters when the coffee beans are processed during the summer monsoon (June to September). It is processed at Mangalore, located in Coastal Karnataka. The processing location experiences heavy rainfall of more than 1000 mm in July, followed by 950 mm in June and 600 mm in August. Out of 3264 mm of annual rainfall, 2852 mm is received during the monsoon period. It accounts more than 80 per cent of annual rainfall. The maximum temperature during the coffee monsooning period varies between 28 and 30°C while night temperature revolves between 22 and 24°C. Being located in the tropics along the West Coast, the crop processing environment in terms of surface air temperature is relatively uniform and moderate with a characteristic feature of heavy clouds and continuous rainfall during the monsoon period. These monsoon features are more predominant from the middle of June to August during which the coffee beans are subjected to monsooning. The coffee beans
bulge in the process of monsooning and the volume increases significantly due to absorption of atmospheric moisture. It is directly related to the monsoonal wind during which coffee beans are processed. The bulging was less in all the samples processed during monsoon 2003, which varied from 2.1 to 2.7 ml/100 number, while it ranged between 2.7 and 5.8 ml/100 number in the samples processed during monsoon 2004.

The Government of India, during 1980s, recognized the necessity to improve the latex yield productivity in the traditional rubber growing regions and also expand these plantations to non-traditional regions to meet the ever increasing demands of natural rubber in India (Sethuraj et al., 1989). Agrometeorological studies were initiated during early 1986 with the appointment of a Scientist (Agrometeorology). To begin with, scientific issues were identified as: (a) delineate the potential non-traditional regions for expansion of rubberplantations, (b) estimate the impact of climatic conditions, especially abiotic  stress conditions on productivity, (c) quantify influence of meteorological factors on the physiological responses towards plant growth and yield attributes, (d) estimate the irrigation requirements to mitigate the drought conditions, and (e) develop weather based predictive models for `Abnormal leaf fall’ disease of rubber plantations. An attempt is made to present synthesis of accomplishments during 1986 to 1992 period of my association with the Rubber Research Institute of India (RRII), Kottayam.

The global economy has adversely been affected to a considerable extent due to weather related disasters like droughts, floods, heat waves and cold waves which are not uncommon in the recent past due to global warming and climate change. For the first time, the year 1998 was declared as the weather related disastrous year globally. The year 2015 was the warmest year globally, again. Such weather phenomenon of warming more and more year after year was noticed in the current decade as well when we look at 2023 and 2024. The year 2010 was the warmest year ever recorded, followed by 2009 in India. The occurrence of floods and droughts, cold and heat waves adversely affected the Indian foodgrains production to a large extent across the Country in one or other region as seen in 2014, 2012, 2009, 2004, 2002 and 1987. The cold wave in winter 2003- 04 across the Northeast region of the Country and the heat wave in summer 2004 across the same region are still in memory to understand the ill effects in agriculture/horticulture/poultry/inland fisheries sectors. Model simulations
indicate that a marked increase in rainfall and temperature over India would be seen during the current century. The maximum expected increase in rainfall is likely to be 10–30% over the Central India. Temperatures are likely to increase between 2 and 30Cby the end of 2100 A.D. However, steps taken towards the green energy across the world may yield results not to allow atmospheric global temperature beyond 1.5 to 20C. Greater number of high surges and increased occurrence of cyclones in post monsoon period along with increased maximum wind speed are also expected along the East Coast of the Country. The summer droughts and heavy rains leading to waterlogging, floods and landslides during the monsoon period is a threat to plantation crops which are predominantly grown in the Humid Tropics like Kerala (8°15` N and 12°50`N latitudes and between 74°50`E and 77°30`E longitudes).

The natural habitat of rubber (Heavea brasiliensis) is rain forests of the Amazon basin, situated within 5° North and South at altitudes below 200m. The climate of this region is equatorial monsoon type characterized by mean
monthly temperature by 25 to 28°C, well distributed rainfall and no marked dry weather. Though it is originated in the Amazon basin, it is now predominantly grown in the tropics where an equatorial monsoon type climate prevails. Regions between 8°N and 10°S which includes Indonesian archipelago, Malaysia, southern part of Sri Lank  and some other Islands, are better suited to rubber cultivation. The production of natural rubber in the country was 8.65 lakh MT in 2008–09, registering a 4.74 per cent growth compared to the previous year. India is the fourth largest producer of natural rubber with a share of eight per cent in the World after Thailand, Indonesia and Malaysia and the fourth largest consumer of natural rubber after China, USA and Japan. Among the rubber growing countries in the World, India occupies a pride place with the top most position in productivity (Table 9.1). The productivity of natural rubber (NR) in India in 2009–10 was 1784 kg/ha. In 1950–51, it was 284 kg/ha. The growth achieved in terms of the productivity of natural rubber is 628 per cent. This achievement

Tea (Camellia sinensis) is one of the most important beverage crops in the World and the second most commonly drank liquid on earth after water. It has numerous medicinal benefits mainly due to its antibacterial and
antioxidant properties. The major tea growing regions of the world are South-East Asia (India and Sri Lanka), Eastern and South Africa consisting of Kenya, Malawi, Tanzania, Uganda and Mozambique. All these countries are producers of black tea. China and Japan are the major producers of green tea. These countries experience cool, tropical humid climate where this crop is being cultivated. However, at present, the crop is also being cultivated in wide range of climates from Mediterranean to warm, humid tropics to include countries such as Russia and Georgia in the northern latitudes and Argentina and Australia in the southern latitudes (Plate 8. 1). The region to which the crop is grown is closely linked with the climate. The crop is grown across wide altitudes up to 2200 m a.m.s.l. Sri Lanka, Kenya, China and Vietnam are the major competitors to India in tea exporting field. China is the major producer of green tea while Sri Lanka and Indonesia are producing mainly orthodox varieties of tea. Tea industry in India occupies an important place in the national economy since last 172 years. It is an essential item of domestic consumption. Tea is also considered as the cheapest beverage amongst the beverages available in India.

Black pepper (Piper nigrum L.), famous as “Black Gold” and also known the “King of Spices” is the most important agricultural commodities of commerce and trade in India. It is the most important, most popular and most widely used spice in the World. Of the total spices traded internationally, black pepper accounts for 34 per cent. South West India is the traditional home of this important spice, particularly the Malabar Coast. Black pepper is also grown in tropical zones such as the Asia Pacific Region, mainly India, Indonesia, Malaysia, Sri Lanka, Thailand, China, Vietnam and Cambodia. Outside the Asia Pacific region, the crop is distributed in Brazil, Mexico, Guatemala, etc., totaling about 26 countries. It is grown successfully between 20°N and 20°S latitude and from mean sea level to 1500 meters above sea level. World’s black pepper production varies in the range of 2.7 to 3.35 tonnes annually. The major production share is contributed by Vietnam with an annual production of 80,000 tonnes. About 85 per cent of the World trade of pepper is determined by the largest pepper producing countries in the International Pepper Community (IPC). World export fluctuates around 1.5–2.5 lakhs tonnes per annum. Global black pepper supply has shown a drastic increase over last ten years except in 2008–09. Vietnam’s sudden increase in production has resulted in the massive global out put of 3–3.5 lakhs metric tonnes from 1.9–2.0 lakhs metric tonnes in late nineties.