eChapters

Most of the plants undergo a period of rest, and in this period, the growth activities temporarily halt. The whole plant looses its aerial parts and undergoes a rest period in the form of rhizome, corm, or tuber. Researchers who study fruit trees use the term rest for dormancy (Samish, 1954). This period is sometimes called as quiescence. The term rest and quiescence can be included under common category dormancy. Some workers differentiate the term dormancy and rest period (Burton, 1964). Wareing and Co-workers (Robinson and Wareing, 1964; Wareing et al., 1964) isolated dormancy inducing substance in sycamore seedlings (Acer pseudoplatanus) which was named as dormin. Further, analysis of this substance by Cornforth et al. (1965) reveals that dormin was identical to Abscisin-II (a substance speeding the abscission of the young flowers of Lupinus luteus and have antiauxin effect).

Dormancy can be defined as an arrest in development of buds, seeds, embryos, or spores under conditions otherwise suited for growth (Taylorson and Hendricks, 1977). It is a survival strategy (exhibited by many plant species), which enables them to survive in climates where part of the year such as winter or dry seasons is unsuitable for growth. The dormancy may be due to the factors within the dormant organ or seed itself and it is called spontaneous dormancy. This type of dormancy is found in seeds, buds and perenating organs like tubers, bulbs, bulbils, corms and rhizomes. In some weeds, dormancy is caused by high or low temperature and this type of dormancy is called as imposed dormancy. Seeds normally germinate in darkness but are inhibited by light are considered to become dormant after exposure to light (Bewley and Black, 1982; 1985). Seeds that require light for germination are said to be photo dormant.

In general terms, dormancy can be defined as a period during the biological cycle of the plant in which growth of the whole organism (seed) or a plant organ (bud, tuber, corm etc.) is suspended eventhough the environmental conditions for growth may be favourable. More specifically, dormancy refers to a condition in which growth is inhibited by a restriction of essential metabolic processes, such as water uptake, gas exchange and cell division, either as a result of endogenous dormancy-controlling factors or in response to exogenous factors such as changes in the environment. It is distinct from a transient state of quiescence or rest imposed by an unfavourable environment in that dormancy persists even when the environment becomes favourable for growth whereas quiescence ceases.

For wild plants, dormancy has evolved as a means of enabling the plant to endure periods of stress due to drought or low temperatures and is therefore critical for the survival of the species. In cultivated arable or vegetable crops, breeding has generally led to a loss of dormancy or a reduction in the length of the dormant period. In arboreal crops of temperate climates, however, bud dormancy is still an essential feature of the annual growth cycle of the tree.

1. The word physiology was first used by Greeks around 600BC to describe a philosophical enquiry into natural things.

2. The word "physis" meaning nature.

3. The discovery of blood circulation by William Harvey in 1628.

4. C.Bernad (181378) who is considered as one of the founder of physiology.

5. The process of transport of an oxygen from outside air into the cells within tissues are called as Respiration.

6. STPD is abbreviated as standard pressure dry.

7. The gill arch along with the filaments is called as gill.

8. Haemoglobin is abbreviated as Hb or Hgb.

9. Cephalopods use haemocyanin- a copper containing protein for oxygen transportation.

10. Protobranch - the gill structure tends to occur in primitive groups and appears as a small leaf like structure.

Flowering is the most important phenological event in the phyotogerontology, as it is the key factor contributing to fruit production and profitability to the orchardists. Under favourable growth conditions the timing and intensity of flowering greatly determine the quantum of production. However, several times there are very contrasting florigenic events where despite prolific flowering, resultant fruit set remains low leading to low yields. Therefore understanding of the various external and internal factors involved in flower induction in mango is crucial for developing suitable orchard management practices to achieve regular and high yield.

Abstract

The availability of the quality seed is the first and the most important requirement which is of great relevance in tree improvement programme. Unlike agriculture, the forestry seeds have great variation in size, shape, dormancy, viability, moisture content, etc. It needs special techniques for collection, handling, processing and storage of the seeds of the large number of forest species. A strong commitment to improving tree seed technology is required for full utilization of seed supplies with the help of recent advances in seed physiology. Substantial improvements have occurred as a result of seed technology research offering the potential for major advances in traditional seed production and distribution systems.

Growth: Growth involve cell division subsequently cell elongation. Increase in volume that is associated with fruit growth largely result of cell division or cell elongation or both. In some fruit such as apple, extension of intercellular space may also contribute the growth. Generally growth by cell division in early stage whereas, cell elongation during later stage.

Two distinct type of growth curve are observed when increase in such variable such as fresh weight, volume and dry weight of fruit.

1. Single sigmoid curve
2. Double sigmoid curve

In case of single sigmoid growth curve firstly there is rapid increase in size then after decline so there is only one rapid growth is observed e.g. Apple, pear, tomato, cucumber and strawberry.

In case of double sigmoid two rapid growth period are separated by an intermediate period that is less growth or no increasing growth curve. Double sigmoid growth curve can be used as two successive sigmoid curve thus there are three clearly define stage of growth.

Fruit ripening is a highly coordinated, genetically programmed and an irreversible phenomenon involving a series of physiological, biochemical and organoleptic changes which finally lead to the development of a soft edible ripe fruit with desirable quality attributes. Ripening is the process where changes take place in the fleshy fruit and make it edible. It represents the unique coordination of developmental and biochemical pathways leading to changes in colour, texture, aroma and nutritional quality of mature seed-bearing plant organs (Barry and Giovannoni, 2007). Physiologically mature fruit is transformed from an unfavourable state of firmness, texture, colour, flavour and aroma to favourable state for consumption. It is the final phase in the development of fruit and involves major metabolic changes and it is normally an irreversible event. The ripening phase does not start until the fruit has developed considerably from the tissues present at anthesis and it is difficult to stimulate ripening before it attains maturity. The ripening changes which are common during softening are accumulation of pigments and changes in cell wall.

Fruits provide a suitable environment for seed maturation and often a mechanism for the dispersal of mature seeds. By anatomical definition, fruit is a mature ovary, and therefore, includes carpel tissues in part or in whole. However, many fleshy fruit species develop mature fruit tissues by including extra-carpellary floral components. The examples include strawberry, pineapple, mulberry and pome fruit (apple, pear, etc.) in which the receptacle, bracts, calyx and floral tube (the fused base of floral organs), respectively constitute majority of mature fruit tissues. Even species with fruit derived from carpel tissue exclusively can display a range of developmental programs, spanning the relatively uniform single expanded carpel or drupe of stone fruit to the differentiated carpel tissues, giving rise to the peel (flavedo) and multi-carpel flesh as observed in citrus and banana. Although genetic selection of agriculturally valuable fruits is being done since centuries but most of the information about how fruits develop, how this development is coordinated with embryonic development and seed formation and the molecular, cellular and physiological events that control fruit growth and differentiation are still lacking. In the following sections, the various aspects controlling fruit setting and development have been discussed.

Introduction
The genetic code and protein synthesis are fundamental processes that underlie the
expression of genetic information within all living organisms. These processes are integral
to understanding how DNA, the hereditary material, dictates the production of proteins,
which are essential molecules that carry out various functions in the body, from structural
support to catalyzing biochemical reactions.
Genetic Code
The genetic code consists of rules that guide the translation of information stored in
DNA or RNA sequences into proteins within living cells. It is nearly universal across
all organisms, underscoring the shared evolutionary origins of life. The genetic code is
composed of codons, which are sequences of three nucleotides in mRNA (messenger
RNA) that correspond to specific amino acids or stop signals during protein synthesis.
Each of the 20 amino acids used in protein synthesis is encoded by one or more codons.
For instance, the codon AUG not only codes for the amino acid methionine but also serves
as the start signal for translation, marking the beginning of a protein-coding sequence. The
redundancy of the genetic code, where multiple codons can specify the same amino acid,
provides a protective mechanism against mutations, as some changes in the nucleotide
sequence do not alter the resulting protein.
Protein Synthesis
Protein synthesis is the process by which cells construct proteins based on the instructions
encoded in mRNA. This process takes place in two primary stages: transcription and
translation.
Transcription: Transcription is the first step of gene expression, where a particular segment
of DNA is copied into RNA by the enzyme RNA polymerase. During transcription, one
of the two DNA strands serves as a template for the formation of a complementary RNA
strand, This newly synthesized RNA strand, known as pre-mRNA, undergoes further
processing, including splicing, capping, and addition of a poly-A tail, to become mature
mRNA, which is then exported from the nucleus to the cytoplasm in eukaryotic cells. In
contrast, in prokaryotes, both transcription and translation occur within the cytoplasm.

Most food legumes have a long history of domestication almost as long as cereals, and during this time they have been subjected to conscious and unconscious selections for better adaptation to environmental condition as well as better seed yield. In general, crops during their ontogeny faces a number of abiotic stress viz., excessive and/or low soil water stress, soil salinity stress, high as well as low temperature stress. It has been well documented that crop yields would be greater in many cropping regions if more water were available. 
Availability of water for agriculture is being challenged increasingly because of growing demand for water from other sectors such as industry, urban use, and for social and environmental purposes. Water stress may conceivably arise either from an insufficient or from an excessive water activity in the plant’s environment. Many physiological characteristics are correlated with the water potential of mesophyll tissue but the correlations are species specific. There is a general hierarchy of sensitivities among general physiological activities. Most sensitive are cell expansion, cell wall synthesis, protochlorophyll formation, and nitrate reduction. Generally turgor pressure is still accepted as the best indicator of water stress in plants. The specific mechanism by which turgor regulate physiological function probably relate to cell walls and membranes. Cell membrane structure, and spatial arrangement of enzyme, transport channels, cellulose synthesis rosettes, and receptor proteins may be dependent on turgor pressure.

Introduction
Cell Cycle: Growth at the cellular level involves the cell cycle, which includes phases of growth (G1), DNA replication (S), and cell division (M). During these phases, cells prepare for and execute division to increase cell numbers. Mitosis and Meiosis: Mitosis results in two identical daughter cells, crucial for tissue growth and repair. Meiosis, on the other hand, is essential for producing gametes (sperm and eggs) and ensures genetic diversity.
Hormonal Regulation
Growth Hormone (GH): Secreted by the pituitary gland, GH stimulates liver cells toproduce insulin-like growth factor 1 (IGF-1), which promotes cell growth and division throughout the body.
Thyroid Hormones: Thyroxine (T4) and triiodothyronine (T3) from the thyroid gland regulate metabolic rate and are vital for normal growth and development, particularly in the nervous system.
Sex Hormones: Estrogens and androgens influence the growth of secondary sexual characteristics and contribute to the final stages of skeletal growth during puberty.
Nutritional Factors
Proteins: Amino acids from dietary proteins are necessary for the synthesis of new proteins and enzymes, which are crucial for cell growth and repair.
Vitamins: Vitamins such as A, C, and D are essential for various growth processes. For instance, vitamin D is vital for bone growth and calcium absorption.
Minerals: Calcium and phosphorus are key for bone development, while zinc and iron are important for cellular functions and overall growth.
Genetic Factors
Genetic Blueprint: Growth patterns and potential are largely determined by genetic factors. Genes influence growth rates, final height, and the development of various body structures.
Growth Disorders: Genetic mutations or abnormalities can lead to growth disorders such as dwarfism or gigantism, illustrating the role of genetics in growth regulation.

Introduction
Intracellular transport of molecules plays a crucial role in maintaining cellular function and organization. The genetic and biochemical processes that regulate membrane trafficking, such as membrane bending, budding, fusion, and fission, ensure the efficient movement of molecules within cells. Despite substantial advances in understanding the molecular aspects of these processes, the broader, or “supramolecular,” regulation of membrane trafficking, which coordinates the overall balance and response to environmental changes, remains less explored. This involves the transport and exchange of membranes and proteins betweenorganelles in a highly organized manner, critical for maintaining cellular homeostasis.
Membrane Trafficking Pathways
Membrane trafficking consists of well-defined pathways connecting cellular compartments like the endoplasmic reticulum (ER), the Golgi apparatus, and the plasma membrane (PM). Proteins and lipids are transferred from the ER to the Golgi and then directed either to the PM or other intracellular destinations. These pathways must be tightly regulated to maintain cellular balance, as any disruptions in membrane flow can lead to cellular dysfunction. In addition to routine cellular maintenance, these pathways must adapt to signals from the environment, ensuring that cells respond appropriately to external stimuli.

Many horticultural and forestry plants don’t come true-to-type when propagated by seed owing to cross pollination and highly heterogeneous nature of fruit crops, in general. As a result, when such plants are grown, the individuals differ in morphological as well as fruit characteristics as compared to mother plant. Though, it was a common practice in old days to establish new orchards with seedling plants, but now with the development and standardization of different vegetative propagation techniques, such plantings are avoided. In modern system of crop production, instead of a single tree derived from seed, use of composite plants (consist of usually scion and rootstock, joined together by budding or grating) is in vogue. This could have been possible by growing interest of mankind in vegetative means of plant propagation.  In asexual propagation, vegetative parts of the plant are used for propagation.  It is practicable because all the living cells of a plant have a capacity to regenerate into a full plant under favourable environmental conditions.

Selye, H (1936), the pioneer in stress physiology, defined stressors as noxious stimuli that increase adrenocorticotropic hormone and clubbed these stimuli under the term stress. Rivier and Rivest (1991) and Chrousos and Gold (1992) defined stress as “a state of disharmony, or threatened homeostasis.” Stress challenges homeostasis, but does not disrupt it, in an adapting organism. McEwen (2000) defined stress as a “real or interpreted threat to physiological or psychological integrity that results in physiological and/or behavioral responses.” The following are the various stressors:

Domestic animals including chicken and mammals, belong to the category of homeotherms, as opposed to poikilotherms. Homeotherms or warm blooded animals are those which are able to maintain constant body temperature in the face of varying environmental temperature. The poikilotherms or the cold blooded animals change their body temperature according to the temperature of the surroundings. Most invertebrates and lower vertebrates belong to the category of poikilotherms.

Why do animals have to maintain constant body temperature? As we are aware that enzymatic reactions in the body are temperature sensitive. In fact, a 10 degree centigrade increase in temperature can result in doubling of the reaction rates. In order to maintain optimum functioning of the enzymatic reactions in the body a constant temperature is required. This constant body temperature is not very constant in the sense that it varies somewhat during exercise and also when the animal is exposed to extremes of temperature of the surroundings. That means that the temperature regulation mechanisms in the body are not 100 percent perfect.

At this stage it is desirable to clarify the distinction between surface temperature and core temperature. The surface temperature, in contrast to the core temperature rises and falls with the temperature of the surroundings. It is the temperature of the deep tissues or internal organs which remains constant. The temperature of the rectum is usually taken as a useful indicator of core temperature because of the ease of measurement. The rectal temperature of several domestic animals is given in Table 1.

Domestic animals –including chicken and mammals, belong to the category of homeotherms, as opposed to poikilotherms. Homeotherms or warm blooded animals are those which are able to maintain constant body temperature in the face of varying environmental temperature. The poikilotherms or the cold blooded animals change their body temperature according to the temperature of the surroundings.

Presently, potato (Solanum tuberosum L.) is the world’s third most important crop, after wheat and rice. Tubers of the potato plant have been used as a primary nutritional staple and a carbohydrate source in many diets and as the basis for a variety of processed products throughout the world. Owing to climate change, potato production is expected to fall in the coming decades, predictions asserting that global potato yields will decrease by 9–18% in most parts of the world. Availability of new varieties less sensitive to these environmental cues is thus crucial to overcome the negative effects of global warming. Of various developmental phases, tuberization is the most sensitive stage in potato limiting its climate associated geographical distribution and actual yield.  Hence, understanding the tuberization process becomes even more important in the face of changing global climate. The induction of tuber formation is a key developmental transition for the production of potatoes.  Understanding the regulation of tuber induction is essential to devise strategies to improve tuber yield and quality.

Physiotherapy may be defined as the use of physical techniques like massage, exercise, heat, cold, sound waves, electric current etc for the treatment of injuries and movement dysfunction. Physiotherapy deals with the treatment of diseases by physical methods. It is used for treating injuries, strain, spasm, painful conditions, sprain of tendons, paralysis, postoperative trauma etc. It improves functioning of nerve, muscles and bones. The aim of physical therapy is the restoration of function and promotion of tissue healing by assisting normal physiological processes. The physiological response to physical therapy is its effect on the vascular supply; this in turn reproduces similar changes in deeper tissues.

Mycotoxins are naturally occurring toxic secondary metabolites produced by molds. More than 25% of world’s food crops are contaminated with mycotoxins (Eskola et al., 2020). Like other environmental pollutants, mycotoxins also harm the health and productivity of animals and poultry. Mycotoxin development typically occurs in the field, during feed processing and storage under unfavourable conditions. Factors such as temperature changes, storage time, and conditions play a crucial role in fungal growth and aflatoxin synthesis.

Introduction
Aquaculture has grown into a significant business and is the fastest-growing agricultural production sector in the world, taking new, intense, and diverse directions (Villa-cruz et al., 2009). Aquaculture has experienced intensification in recent years attributable to escalating stocking densities and excessive feed utilization, which have imposed stress on aquatic organisms and ultimately inhibited their growth and immune functionality. Chemotherapy remains a principal approach for the treatment and prevention of aquatic diseases. Nevertheless, a plethora of scholarly articles have indicated that chemical therapeutics exert adverse effects on both human health and ecological systems. The aquatic environment is adversely affected by antibiotics and their residuals, as a significant proportion of bacterial strains are developing resistance to these pharmaceuticals within the ecosystem. Consequently, there has been a concerted emphasis on the exploration of environmentallysustainable alternatives (Kumar et al., 2020). The public increasingly recommend natural compounds, while the utilization of synthetic chemicals, hormones, and antibiotics is increasingly becoming impractical owing to consumer apprehensions and stringent regulatory frameworks in numerous nations (Chakarborty et al., 2014).
Phytobiotics can be conceptualized as products originating from plants that are incorporated into animal feed to optimize performance in aquatic species. Predominantly, leaves, roots, tubers, or fruits of various herbs, spices, and other botanical sources may be utilized as phytobiotics (Arts and Hollman, 2005). These substances are typically employed to promote enhanced growth performance in the cultivation of shrimp and fish. Based on their processing characteristics, phytobiotics are divided into categories: