eChapters

Introduction

The optimum soil pH for plant production is one that is slightly acidic, at this pH soil microorganisms are most active and plant nutrients are readily available. At extremes of high (alkaline) and low (acidic) pH this delicate balance is disturbed and plant nutrients that were in adequate supply can become either deficient or toxic to plant growth. Some essential nutrients such as phosphorous, calcium, magnesium and molybdenum become unavailable if the soil pH becomes too acidic. Acidic conditions will result in a lowering of plant production in farming systems. This will result in reduced profitability and an increased reliance on fertilizers to sustain any form of productive agriculture. Correcting soil pH to a more favorable pH range will increase the availability of essential nutrients.

Introduction

Soil is one of the crucial natural resources that support life on the earth and controls the economic conditions of the nation. Soil erosion has become a serious problem in both rainfed and irrigated areas of India thus it of vital importance to raise awareness about soil erosion and their reclamation / management methods, so that future land management decisions can lead to more sustainable and resilient agricultural systems. In India almost 130 million hectares of land, i.e., 45 % of total geographical surface area, is affected by serious soil erosion through gorge and gully, shifting cultivation, cultivated wastelands, sandy areas, deserts, and water logging.

In India, the soil is eroded at an average annual rate of 16.35 tonnes per hectare which means 5334 million tonnes per year for the country as a whole. Out of this, about 29 per cent is permanently lost to the sea, while 61% is simply transferred from one place to another, and the remaining 10% is deposited in reservoirs (which mean the storage capacity is reduced by 1-2 per cent annually (Narayana and Ram Babu, 1983)). Singh et al. (1990) estimated that the average annual soil loss is about 15.2 tonnes per hectare and at national level it amounts to about 4978 million tonnes annually. The annual erosion rates vary from region to region. In dense forests covers, snow-clad cold deserts and arid regions of western Rajasthan, the annual erosion rates are less than 5 tonnes per hectare. On the other hand, about 64 per cent of the total soil is contributed by highly to very severely eroded areas, such as the Shiwalik hills (annual rate is more than 80 tonnes per hectare), the Western Ghats, black and red soil regions, ravines and other gully eroded areas and the northeastern region. For the first time, Gurmel Singh prepared map of soil erosion in India (Fig. 7.1), on the basis of iso-erosion lines i.e. line joining the place of same erosion rates.

Submerged soils/Flooded soil

Submerged soils are the type of soils that are saturated with water for a sufficiently long time in a year. This gives the soil the following distinctive gley horizons resulting from oxidation-reduction processes:

The soil is intermittently saturated with water, oxidation of organic matter is slow and it accumulated within the “A” horizon. Fe and Mn are deposited as rusty mottles or streaks if the diffusion of O2 into the soil is slow in the second horizon, whereas if the diffusion is rapid, they are deposited as concretions.

Types of submerged soils

1. Waterlogged soils- Waterlogged soils are saturated with water for a sufficiently long time annually to give the soil the distinctive gley horizons resulting from oxidation-reduction processes. Saturation with water may be due to impermeability of the soil material, or the presence of an impervious layer, or a high water table.

2. Marsh Soils- These types of soils are more or less permanently saturated or submerged. Freshwater marshes can be classified according to their origin into upland, lowland, and transitional. Upland marshes are poor in bases and have pH 3.5-4.5 because they receive mainly rainwater. Lowland marshes are saturated or submerged with water-carrying bases and have pH 5.0-6.0.

Introduction

Environment pollution is a burning topic of the day. Air, water and soil are being polluted alike. Soil being a “universal sink” bears the greatest burden of environmental pollution. It is getting polluted in a number of ways. There is importance in controlling the soil pollution in order to preserve the soil fertility and increase the productivity. Pollution may be defined as an undesirable change in the physical, chemical and biological characteristics of air, water and soil which affect human life, lives of other useful living plants and animals, industrial progress, living conditions and cultural resources. A pollutant is something which harmfully interferes with health, comfort and environment of the people. Most pollutants are introduced in the environment by waste, accidental discharge, sewage or else. They are by-products or residues from the production of something useful. Due to this our valuable natural resources like air, water and soil are getting polluted. The basis of agriculture is Soil. All crops for human food and animal feed depend upon it. We are losing this important natural resource by the accelerated erosion to some extent. In addition to this the huge quantities of man-made waste products, sludge and other product from new waste treatment plants, and even polluted water are also causing or leading to soil pollution. In order to preserve the fertility and the productivity of the soil.

Introduction

Calcareous soils are those that contain high levels of calcium carbonate (CaCO3 ) that affects soil properties related to plant growth, such as soil water relations and the availability of plant nutrients (Elgabaly, 1973), and give effervescence visibly releasing CO2 gas when treated with dilute 0.1 N hydrochloric acid. The pH of calcareous soil is > 7.0 and also regarded as an alkaline (basic) soil.

Calcareous soils have often more than 15% CaCO3 in the soil that may occur in various forms (powdery, nodules, crusts etc.). Soils with high CaCO3 belong to the Calcisols and related calcic subgroups of other soils. They are relatively widespread in the drier areas of the earth. They occupy >30% of the earth’s surface, and their CaCO3 content varies from just detectable up to 95% (Marschner, 1995).

Formation of calcareous soils

Calcareous soils occur naturally in arid and semi-arid regions because of relatively little leaching. They also occur in humid and semi-humid zones if their parent material is rich in CaCO3 , such as limestone, shells or calcareous glacial tills, and the parent material is relatively young and has undergone little weathering. Some soils that develop from calcareous parent material can be calcareous throughout their profile. This will generally occur in the arid regions where precipitation is scarce. It has been estimated that these soils comprise over one-third of the world’s land surface area (Taalab et al. 2019, Aboukila et al. 2018).

Introduction

Desert soils are the soils of arid regions that remain dry for most part of the year and support sparse xerophytes. The amount of water received by precipitation is far less than what is lost by evapotranspiration. Most deserts receive an average precipitation of less than 400 mm. Because of extreme imbalance between evapotranspiration and precipitation, many desert soils contain salts.

Distribution

Deserts occupy about one-third of the areas of Africa and Australia, 11% of Asia and about 8% of the Americas (Boul et al. 1997). Desert soils include both cold and hot desert. In India, desert soils occur in three agro-ecological regions (AER). The cold arid desert of extreme north (Leh, Ladakh region of Jammu & Kashmir ), the hot arid desert of north western India (Rajasthan, southern parts of Haryana and Punjab and northern parts of Gujarat) and the tropical arid desert of the Deccan plateau in South India represents AER 1, 2 and 3, respectively. The three different desert regions in India have characteristic climatic and soil conditions.

Introduction

Black cotton soils are formed by the solidification of molten magma; it covers a large area of the Deccan plateau. The depth of this soil is very high in the lower part of the Krishna – Godavari basin. The clay fraction is very high which is responsible for the heavy waterlogging in the area of heavy rainfall and become more vulnerable to soil erosion. The fine fraction of soil not allows draining out through the soil profile and at the same time the rate of evaporation is low. During summer soils suffer from moisture stress and it becomes very hard but at the same time during the rainy season moisture content very high. this imposes severe constraints on conventional agriculture use as a result most of the land remains fallow and subjected to soil erosion due to heavy rain. The nutrient status of the soil is quite good in Vertisol but these constraints limit crop production. To manage black cotton soil for crop production it is advisable to use animal-powered devices for surface soil drainage, Counter cultivation, adoption of a new cropping system will be helpful for better crop production.

Introduction

Irrigated agriculture is dependent on an adequate water supply of usable quality. The water quality used for irrigation is essential for the yield of crops, maintenance of soil productivity, and protection of the environment as well. The quality of irrigation water is defined with respect to its effect on plant growth, soil properties, soil biological equilibrium, and irrigation technology. Conceptually, water quality refers to the characteristics of a water supply that will influence its suitability for a specific use, i.e. how well the quality meets the needs of the user. Specific uses have different quality needs and one water supply is considered more acceptable (of better quality) if it produces better results or causes fewer problems than an alternative water supply. For example, good quality river water which can be used successfully for irrigation may be unacceptable for municipal use without treatment to remove its sediment load. Similarly, snowmelt water of excellent quality for municipal use may be too corrosive for industrial use without treatment to reduce its corrosion potential.

Introduction

One of the most common concerns in irrigated agriculture is regarding water quality or salinity. Out of the ground water surveyed in different Indian States, as much as 84% is rated either saline or alkaline (Minhas 1996). Salinity management is very important for using saline water in irrigation safely. This requires an understanding of how salts affect soil as well as plants, of how hydrogeologic processes affect salt accumulation, and also of how cropping and irrigation activities affect soil and water salinity.

The objectives of management practices for getting optimal crop production with saline irrigation water include the prevention of salt build-up in soil which limit the productivity of soils and the control of salt balances in the soil-water system, as well as minimising the damaging effects of salinity on crop growth (Meiri and Plaut 1985). Amongst the various soil, water, and crop management options available, there is usually no single way to achieve safe use of saline water in irrigation but many different approaches and practices can be combined into satisfactory irrigation systems using saline water. The appropriate combination depends upon edaphic, hydrogeologic, climatic factors as well as social and economic condition of the farmer. Several practices interact with each other, and should be considered in an integrated manner, along with climatic and human factors. Because of the climate, the basic principles of saline water management need some adaptation, e.g. providing for a leaching requirement is not appropriate when the growing season for post-monsoon winter crops starts with a surface-leached soil profile, because it would increase the salt load. High salinities during the initial stages of growth are particularly harmful. Recommendations for effective management of irrigation water salinity depend upon local soil properties, climate, and water quality; options of crops and rotations; and irrigation and farm management capabilities

Remote sensing

It is the art and science of obtaining information about an object, area, or phenomenon through the analysis of data acquired by a device without being in physical contact. Remote sensing technology involves acquiring information about the earth’s surface and atmosphere, using satellite based sensor, interpretation, of spectral measurements and characterization of land resources and environmental phenomena.

The information recorded by this technology is not visible to humankind. It provides synoptic view as well as three-dimensional view of larger area. And data are received periodically and helps in monitoring the changes at short intervals. The data recording is unbiased one which is stored permanently and can be used in many applications. Thus, processing of data is faster than the conventional interpretation method. Thus, soil resources data collected by extensive ground surveys and soil maps were prepared using cartographic techniques these were tedious, costly and time consuming. Multi date, multi spectral and real time satellite data provide a reliable accurate tool for assessment and repeat coverage of the same area at the same local time for monitoring soil resources (Joshi, 2013). In remote sensing, reflected energy from the object is recorded by a sensor. The information about the object is obtained through the analysis of reflected rays. Three energy interactions occurs when electromagnetic energy falls on any surface feature i.e., reflection, absorption and transmission.

Introduction

The term multipurpose trees (MPT) refers to all woody perennials that are grown to provide more than one significant function (shelter shade, land sustainability) of the land use system they implement. More emphasis is given to trees which are indigenous in nature and have the capability to fix atmospheric nitrogen. All trees are said to be multipurpose. The term “multipurpose” as applied to trees for agroforestry refers to their use for more than one service or production function in an agroforestry system (Burley and Wood, 1991).

Multipurpose trees species (MPT) are grown to provide more than one significant crop of function or form. These may include fuel wood, fiber, fodder, flower, fruit, fertilizer (6F) timber, industrial purpose, nitrogen f ixing, soil conservation, soil protection and rehabilitation, shade and nurse trees, medicine, windbreak, shelterbelts, live fences, aesthetic or recreational purpose, shown in Table 16.1.

Introduction

Soil pollution is anything that causes contamination of soil and degrades the soil quality. It occurs when the pollutants causing the pollution decrease the quality of the soil and convert the soil inhabitable for micro and macro organisms living in the soil. Soil pollution can occur either because of human activities and/or natural processes. However, mainly it is due to human activities. The soil contamination can occur due to the presence of chemicals such as ammonia, pesticides, lead, herbicides, mercury, nitrate, naphthalene, petroleum hydrocarbons, etc. in an excess amount.

Soils can be polluted with several organic and inorganic pollutants. Organic pollutants contain hazardous persistent organic compounds viz. polychlorinated dibenzofurans (PCDFs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins (PCDDs), polychlorinated biphenyls (PCBs), polychlorinated naphthalines (PCNs) and other persistent organic compounds. Inorganic pollutants contain heavy metals like lead (Pb), cadmium (Cd), mercury (Hg), zinc (Zn), copper (Cu), arsenic (As) and nickel (Ni) as well as some radioactive compounds or radionuclides. The major sources of soil pollutants are anthropogenic. It contains mainly two sources, point and diffuse; the point sources contains industrial wastes, municipal wastes, domestic wastes, medical wastes, agrochemicals, agricultural wastes, composts and sludges and nuclear wastes. Organic and inorganic soil pollutants can be toxic for plants, animals soil organisms and others. Some compound of the soil pollutants enter into the food chain and can adversely affect on human health. Soil pollutants can be also transferred to surrounding air and water through leaching, volatilization, runoff and dust storms. Quality of air and water adversely affected can be degraded. Thus, remediation of polluted soils has become an awful necessity in many areas of the world.

Introduction

Land capability classification is one of the very important issues in terms of sustainable land use. Land is the most valuable natural resource which needs to be harnessed according to its potential. Land use planning and management is a known strategy for achieving sustainable development. A properly prepared land use plan based on sound scientific and technical procedures, and land utilization strategies can summarize rationally the future demands. This accompanied by a strong planning process, where communities and various stakeholders are involved, can strengthen the decision making process on allocation and utilization of land resources. Land capability is referred as suitability of the land based on inherent characteristics of the soil associated land features, and climatic conditions that limit their safe use under agriculture, forestry etc. Land capability classification is a system of grouping soils primarily on the basis of their capability to produce common cultivated crops and pasture plants without deteriorating over a long period of time. The capability classification is one of a number of interpretive groupings of soils made primarily for agricultural purposes, mainly based on the inherent soil characteristics, external land features and climatic factors that limit the use of land for agricultural purposes. The land capability is governed by the different land attributes such as the type of soil, its depth and texture, underlying geology, topography, hydrology, etc. It also includes soil irrigation classes and ground water table position to decide overall suitability of lands for sustained use under irrigation. The classification points out automatically the possibilities and limitations of the climate and soil for each crop and type of agriculture.

Introduction

Before start of this chapter some pertinent questions need to be answered. What are different agro ecology and what are the problem soils. Since dawn of agriculture in early 2000 B.C. man has been doing agriculture as subsistence farming to cater the needs for his own consumption. Later on as the population increased, the availability of land per pearson reduced and further the commercialization of agriculture after world war II, particularly in industrialized nation, compelled farmers to increase productivity per unit area. The green revolution involving higher fertilizer uses, more use of agrochemicals together with evolvement of improved crop varieties in later part of twentieth century played vital role in producing higher grain production resulting the global production triplet in contrast to merely increase in total global cultivated area to the extent of 10%.

The catastrophe of green revolution was realized in later years when reports of soil health degradation started appearing. Intensified agriculture characterized by excessive use of fertilizers, agrochemicals and unsupportable level of over exploitation of natural resources led to serious degradation of ecosystem. Thus management of agroecosystem has reached to a crossroad with serious pressure to increase productivity simultaneously holding the soil health with prime concern for future generation. Thus the soil heath under different agroecosystem are posing problem as the soil productivity has not reached to plateau level but has started reducing year after year. Thus such soils are becoming problem which need special attention to bring them back to support higher crop production.

Arrangement of plants and animals into groups according to their close resemblance, naming and describing them is called classification. Classifying the plants into groups is called systematic botany. The main aim of classification is to name the plant to describe them and to bring out their resemblances in order to throw light on their relationship and common ancestor. It is to indicate primitive and advanced plants systematically.

Need for Classification

It is not possible for anyone to study all the organisms. But if they are grouped in some convenient way the study would become easier as the characters of a particular group or a family would apply to all the individuals of that group. Classification allows us to understand diversity better.

Classification of plants

Entire plant kingdom is divided into four main groups.

1. Thallophyta 2. Bryophyta 3. Pteridophyta 4. Spermatophyta or Phenerogams

Development of Plant Body

A vascular plant begins in existence as a morphologically simple unicellular zygote (2n). The zygote develops into the embryo which in the long run develops into the mature sporophyte. The development of the sporophyte (2n) involves division and differentiation of cells and organization of cells into the tissue systems. The embryo of the seed plant possesses relatively simple structure as compared to the mature sporophyte. The embryo bears a limited number of parts containing generally only axis bearing one or more cotyledons. The cells and the tissues of this structure are less differentiated. However, the embryo grows further, because of the presence of the meristems, at two opposite ends of the axis, of future shoot and root. After germination of the seed during development of the shoot and root new apical meristems appear which cause a vegetative growth and reproductive stage of the plant attained.

Fundamental Parts of the Plant Body

The plant body consists of a number of organ i.e., root, stem, leaf and flower. Each part has different functions for plant growth.Flower consists of sepal, petals, stamens, carpels and sometimes also sterile members. Each organ is made up of number of tissue systems; each tissue system consists of number of tissues. Tissue consists of group of cells that are alike in origin, structure and function.

Meristematic Tissues

These are composed of cells that are in state of division or retain the power of dividing. These cells are essentially alike and isodiametric. They may be spherical, oval or polygonal and their walls thin and homogeneous; the protoplasm in them abundant and active with large nuclei, and the vacuoles small or absent.

Classification of Meristems

Meristems are classified in different ways on the basis of certain factors.

A) According to their origin and development

1. Promeristem or primordial meristem

2. Primary meristem and

3. Secondary meristem.

Primary Dicot Stem

A stem with only primary permanent tissues is called primary stem. It represents a young stem. The different tissues present in dicot stem are arranged in concentric layers. e.g. Sunflower

I) Epidermis

Epidermis is the outermost layer of the stem. It is made up of compactly arranged parenchymatous cell, which look rectangular in transverse section. The cells are transparent and devoid of chloroplasts. The outer walls are convex, thickened and cutinized. On the outer side they possess a layer of cuticle. The internal walls of the epidermal cells are thin. The radial walls are thick towards the outer side and gradually become thin towards the inner side. Pits occur in the radial walls. The epidermis of sunflower bears several unbranched multicellular hair. At place the epidermis contains minute pores called stomata or stoma. Each stomata or stoma has a pair of specialized kidney shaped cells called guard cells. The guard cells have a few chloroplasts. By their swelling, the two guard cells can form a pore between them.

Primary Dicot Root

A young dicot root which does not possess secondary tissues but only the primary permanent tissues (tissues derived from the apical growing point) is called primary dicot root. It is generally cylindrical in outline and possesses the following tissues.

I) Epiblema or Piliferous Layer

It is the outermost layer of the root. It is made of compactly arranged thin walled and slightly elongated parenchymatous cells. Epiblema of a root differs from the epidermis of the stem in being devoid of distinct cuticle and stomata. Some cells of the epiblema give rise to thin – walled tubular outgrowths called root hairs. In some plants the root hair mother cells are shorter in comparison to other epiblema cells. The root hairs and piliferous layer (pilus – hair, ferre to carry). The root hair and thin walled epiblema cells absorb water and mineral salts from the soil. Root hairs commonly do not live for more than one week. With their death the epiblema cells become suberised and cutinised.

II) Cortex

It lies below the epiblema. The cortex is made up of many layers of thin walled parenchyma cells. The parenchyma cells may be rounded or angular. They enclose inter-cellular spaces for diffusion of gases.The cells of the cortex store food. They also conduct water from the epiblema to the inner tissues.

Secondary Growth in Dicot Stem

The formation of secondary tissue from the lateral meristem is called secondary growth. It increase in diameter of the stem. A stem with secondary tissues is called secondary stem. Secondary tissues are formed by two types of lateral meristem, vascular cambium and cork cambium or phellogen. Vascular cambium produces secondary vascular tissues while phellogen form periderm. Secondary growth occurs in perennial dicots such as trees and shrubs. It is also found in the woody stems of herbs. In such cases, the secondary growth is equivalent to one annual ring, e.g. sunflower.

Formation of secondary vascular tissues

They are formed by the vascular cambium. Vascular cambium is produces by two types of meristems: intrafascicular and interfascicular cambium.

1. Intrafascicular cambium is a primary meristem which occurs as strips in vascular bundles.

2. Interfascicular cambium arises secondarily from the cells of medullary rays which occur at the level of intrafascicular strips.

3. These two types of meristematic tissues get connected to form a ring of vascular cambium

The tissue system

A group of tissues performing a similar function irrespective of its position in the plant body is called a tissue system. In 1875, Sachs recognized three tissue systems in the plants.

a) Epidermal tissue system

b) Vascular tissue system

c) Fundamental tissue system.

a) Epidermal tissue system

Epidermal tissue system is the outermost covering of plants. It consists of epidermis, stomata and epidermal outgrowths. Epidermis is generally composed of single layer of parenchymatous cells compactly arranged without intercellular spaces. But it is interrupted by stomata. In leaves, some specialized cells which surround the stomata are called the guard cells. Chloroplasts are present only in the guard cells of the epidermis. Other epidermal cells usually do not have chloroplasts. The outer wall of epidermis is usually covered by cuticle. Stoma is a minute pore surrounded by two guard cells. The stomata occur mainly in the epidermis of leaves. In some plants such as sugarcane, the guard cells are bounded by some special cells. They are distinct from other epidermal cells. These cells are called subsidiary or accessory cells. Trichomes and root hairs are some epidermal outgrowths. The unicellular or multicellular appendages that originate from the epidermal cells are called trichomes. Trichomes may be branched or unbranched. Rhizodermis has two types of epidermal cells - long cells and short cells. The short cells are called trichoblasts. Root hairs are produced from these trichoblasts.

The macroscopic characteristics of wood give the clues to the conditions under which the wood is grown, provide an indication of physical properties and serve as an aid in wood identification.

Growth rings do not always appear as distinct alternating bands of earlywood and latewood. Some hardwoods, for example, form large-diameter pores early in a growing season and much smaller pores later in the year; such woods are called ring-porous. Discontinuous rings are occasionally found in trees having one-sided crowns and in heavily defoliated, suppressed, and over mature trees. Examination of a stem cross-section often reveals a dark-colored center portion surrounded by a lighter-colored outer zone. The dark center area is known as heartwood and the lighter tissue as sapwood. Trees in which fibers are spirally arranged about the stem axis are said to have spiral grain.

Wood can often be identified by macroscopic characteristics, particularly by colour, gloss, odour, weight and structure. Wood have two types of features:

A) Macroscopic or Gross feature

B) Minute structure feature

The microscopic features reveals that wood is composed of minute units called cells. The fundamental differences between different kinds of woods are founded on the types, sizes, proportions, pits and arrangements of different cells that compose the wood. Softwoods have a simpler basic structure than do hardwoods due to the presence of only two cell types, and relatively little variation in structure within these cell types. Hardwoods have greater structural complexity because they have both a greater number of basic cell types and a far greater degree of variability within the cell types. In each case, however, there are fine details of structure that could affect the use of a wood.

The structure of a typical softwood is relatively simple. The axial or vertical system is composed mostly of axial tracheids, the radial or horizontal system and the rays, are composed mostly of ray parenchyma cells. According to estimates, 1 cubic metre (about 35 cubic feet) of Spruce wood contains 350 billion to 500 billion cells. The basic cell types are called tracheids, vessel members, fibres, and parenchyma

The structure of a typical hardwood is much more complicated than that of a softwood. The axial or vertical system is composed of fibrous elements of various kinds of vessel elements in various sizes and arrangements, and axial parenchyma cells in various patterns and abundance. Like softwoods, the radial or horizontal system are the rays, which are composed of ray parenchyma cells, but unlike softwoods, hardwood rays are much more diverse in size and shape.

Physical properties of wood

The versatility of wood is demonstrated by a wide variety of products. This variety is a result of a spectrum of desirable physical characteristics or proper ties among the many species of wood. In many cases, more than one property of wood is important to the end product. For example, to select a wood species for a product, the value of appearance-type properties, such as texture, grain pattern and color, may be evaluated against the influence of characteristics such as machinability, dimensional stability and decay resistance.

Cell walls mainly consist of cellulose, hemicellulose, and lignin in a 4:3:3 ratio. This ratio differs from sources such as hardwood, softwood, and herbs. Besides these three components, natural lignocellulosic materials contain a small amount of pectin, nitrogenous compounds, and the secret ash.

1. Cellulose

2. Hemicellulose

3. Lignin

Cellulose

Cellulose is a glucan polymer consisting of linear chains of 1,4-ß -bonded anhydroglucose units. Cellulose is the structural component of the primary cell wall of the green plants.About 33% of all plant matter is cellulose (the cellulose content of cotton fiber is 90%, that of wood is 40-50% and that of dried hemp is approximately 45%. Cellulose is a straight chain polymer.The number of sugar units in one molecular chain is referred to as the degree of polymerization (DP).Cellulose is insoluble in most solvents including strong alkali. It is difficult to isolate from wood in pure form because it is intimately associated with the lignin and hemicelluloses.

Ring Porous

• having vessels more numerous and usually larger in cross section in the springwood with a resulting more or less distinct line between the springwood and the last season’s wood— compare diffuse-porous.

• In some species (e.g. Oak (Red Oak, White Oak) Teak and ash elm, hickory), the largest pores are in the earlywood while those in the latewood are more evenly distributed and uniform in size.

• These woods typically have distinct figures and patterns, and the uneven uptake of stain (the large pores soak up more colour) make the figure more pronounced.

• These are also known as open-grain woods

Semi-ring porous or Semi-diffuse porous

• In some species (e.g. Butternut, Black Cherry, Black Walnut, Pecan, Tanoak), pores are large in the earlywood and smaller toward the latewood, but without the distinct zoning seen in ring-porous woods.

• Also, some species that are usually ring-porous (e.g. Cottonwood) occasionally tend toward semi-ring porous.

Seed bearing plants

Seed-bearing plants are broadly categorized in two major types: the gymnosperms and the angiosperms which are together grouped in Division Spermatophyta in the older system of classification for the plant kingdom. Consequently, seed plants are presently classified into multiple phyla. Still, for the purpose of learning basic concepts, it is convenient to group plants informally as spermatophytes (sperm "seed" + phyte "plant"). The spermatophytes are the most complex and evolutionarily advanced plants. Unlike ferns and bryophytes which reproduce and disperse by unicellular spores, spermatophytes reproduce and disperse by means of multi-cellular seeds which consist a protective seed coat surrounding an embryonic sporophyte and its food supply. This group of seed plants exhibits an alternation of generations in which the sporophyte is dominant. Furthermore, the gametophyte is microscopic and heterosporous with the latter term meaning that these seed plants produce two types of spores: microspores and megaspores that give rise to separate male gametophytes (micro-gametophytes) and female gametophytes (mega-gametophytes) respectively. The megaspore is never released from the sporangium; thus, the female gametophyte develops within the sporangium while being still attached to the sporophyte.

The collection of cones/fruits and seeds is the first step in the harvest, processing, and storage of seed in which man interacts with nature in determining ultimate seed quality. Successful collection, therefore, depends on understanding seed maturation and dispersal characteristics of each species, knowing local weather trends, and evaluating crop quality. Collection of propagating material is an expensive process and it is therefore also important that areas wherein cones and seeds are to be collected are evaluated to determine whether a sufficiently heavy crop to permit economic collection of seeds is present and whether the seed zone and elevation represented by the candidate area is appropriate for the production of seedlings needed in the reforestation program. Remember that properly collected, processed, and stored seeds may remain viable for a decade, so evaluation of seed needs may be projected well in advance of current harvest schedules through proper planning and organization of seed collection.

The decision whether to extract the seed from the fruit at a central seed processing depot or close to the site of, and soon after, collection must be made in the light of local conditions. The reduction in bulk and weight of the collected material greatly facilitates transport and for this reason the extraction of the seed from relatively bulky fruits may be desirable at the site close to the collection area. In some cases it has also been found that early extraction of the seed is essential to maintain maximum viability. The use of the sun drying to speed extraction of the seed is common for many conifers and trees with woody dehiscent fruits. However, too rapid drying of fruits may sometimes cause them to remain closed and prevent later extraction, a condition known as “case-hardening” of cones. This is true for the cones of some pines if they are collected before peak maturity. In such cases it is necessary to keep the fruits under cover, with a good circulation of air, for one or two weeks before more rapid drying is attempted.

Seed dormancy

Plants evolve many mechanisms that ensure their survival. For instance, some species produce prodigious number of seeds so that even if only a small proportion germinate and grow, some seedlings will survive. Alternately, dormancy can be defined as: a seed characteristic, the degree of which defines what conditions should be met to make the seed germinate. This definition may be more useful in understanding dormancy because it suggests that dormancy is variable, rather than constant, which is the situation that we generally encounter in the native populations of many species. The staggering of germination (dormancy) is an advantage for seeds that mature in late summer to early fall, since immediate germination would leave vulnerable seedlings exposed to harsh winter conditions.

Seed testing

No matter how good processed seed may look, the actual value is the number of seedlings it will produce. Testing of seeds is therefore imperative to determine and identify the changes that have occurred from the time of collection until the seeds are sold or sown at one time. The critical step in evaluating a seed lot is the drawing of representative sample. Place all the test samples in a bucket, mix them thoroughly and subdivide to obtain sample size. Improvements in seed processing can only be obtained with quality control. These evaluations should be made in the processing plant and at a seed testing laboratory. The National Tree Seed Laboratories offers a free service to evaluate processing machinery. You need only collect a small sample of seed after it has been processed by each machine and send it to the laboratory. Be sure all the seed comes from the same lot so all samples are related. Each machine must be adjusted for efficient operation, and proper adjustment requires monitoring of the operation.

Need for certification

Forest restoration and reforestation experts know the effect the right seed source can have on the long-term economic and ecological success of tree planting efforts. However, unlike stock quality (such as size and health), genetic quality (seed source) cannot be observed by the consumer at the time of stock purchase. Where once the provincial government controlled the source of seed and its destination through the provincial nursery system, seed supply is now in the private sector, and the source is unknown or a matter of trust. Tree planting in general needs help, and the wrong seed source is only one of the many reasons that your planting project may not be successful. Besides, the identity of the source will be tracked throughout the chain of custody until it is presented, as a labeled, certified product to the consumer. The seed source may be from a single parent tree or preferably from a large healthy stand of trees. But if seed is bulked from many locations, the label on the resulting seedlings can only indicate the greater area. For example if a nursery bulked its seed from many counties across a specific place, they can only certify and market that crop as? specific place? not as one from a specific county that may have been a source for the seed. For this reason we will have to encourage collectors and growers to bulk only by tree seed zones to promote certification program for the context of successful tree planting.

Fruits and vegetables are important supplement to the nutritional requirements in the human diet as they provide the essential minerals, vitamins, flavonoids/ antioxidants and dietary fiber required for maintaining health. India is the second largest producer of fruits and vegetables in the world after China. During 2012-13, fruits and vegetables have registered a production of about 77.7 million MT and 159.5 million MT respectively (NHB, 2013. However, increase in production has not matched with the improvement in infrastructure for post-harvest management and processing. Fruits and vegetables are highly susceptible to deterioration owing to their high moisture content and delicate nature. Besides, most of the fruits and vegetables are seasonal in nature leading to glut in the local market during peak season resulting in huge economic losses to the growers. According to an estimate, 6-18% of fruits and vegetables are lost in the supply chain right from harvest to consumption due to lack of infrastructure for postharvest management, processing and value addition (Nanda et al., 2012).

2.1 Introduction

Food Pipeline refers to a post harvest system which deals with ensuring the delivery of a crop from the time and place of harvest to the time and place of consumption, with minimum loss, maximum efficiency and returns to all concerned including grower, processors and consumer. The term system represents a dynamic, complex aggregate of locally interconnected functions or operations within a particular sphere of activity. While, the term pipeline refers to the functional succession of various operations but tends to ignore their complex interactions.

2.2 Stages of postharvest system

The food commodities broadly undergo different stages/operations of post harvest systems right from harvest till consumption.

1. Harvesting

2. Threshing (food grains, pulses and oilseeds)

3. Drying (food grains, pulses and oilseeds)

3.1. Introduction

Food preservation can be defined as the science which deals with the process of prevention of decay or spoilage of food thus allowing it to be stored in a safe condition for future use. Scientifically, preservation may be defined as a science which deals with the process for prevention of decay. All foods gradually undergo deterioration or spoilage from the time they are harvested or manufactured. Some commodities spoil rapidly, while others can keep for longer but limited periods. Spoilage in the food products may be caused due to some physical, chemical and microbial changes during storage. The preservation of these products can be resulted by controlling following physical, chemical and microbial changes.

4.1. Introduction

Food occupies first position among the basic needs of human beings. Food processing dates back to the prehistoric age when crude processing including various types of cooking, such as over fire, smoking, steaming, fermenting, sun drying and preserving with salt were in practice. These crude processing techniques remained essentially the same until the advent of the industrial revolution. However, the change in food habits and the quality consciousness of the consumers in the developed world raises the need of advancements in development of food processing like spray drying, juice concentrates, freeze drying and also introduces dried instant soups, reconstituted fruit juices, and self cooking meals such as ready-to-eat food rations etc., during 20th century.

5.1. Introduction

Food processing units range from home-based businesses to large-scale processing plants. The food processing sector is a highly fragmented industry which includes fruit, vegetables, dried, preserved, canned, pulps, pickles, chutneys, milk, dairy products, ready-to-serve products, frozen desserts, meat, poultry, marine products, grain processing, beer and alcoholic beverages, consumer, convenience and packaged food, soft drinks etc.

The main objective of fruit and vegetable processing is to supply wholesome, safe, nutritious and acceptable food to consumer throughout the year. Fruit and vegetable processing also aim to replace import of products such as squashes, jams, tomato sauces, pickles, etc., besides earning foreign exchange by exporting finished or semi-processed products. The fruit and vegetable processing industries are also established in the developing countries due to following reasons:

• Reduction in fruits and vegetables post harvest losses

• Industrialization policy of the government

• Generate both rural and urban employment

• Improve farmer s nutrition by self consumption of processed fruits and vegetables during off season

6.1. Introduction

Chemical preservatives are those substances which minute organoleptic and physico-chemical properties . Preservation of food products with chemical preservatives is usually based on the combined or synergistic activity of several additives, intrinsic product parameters (e.g. composition, acidity, water activity) and extrinsic factors (e.g. processing and storage temperature).

Many chemical substances are added to the food for functional purposes and are called as additives and in many cases these are found to occur naturally in some foods. An additive is defined as a substance or mixture of substances other than basic food ingredient present in a food as a result of any aspect of production, processing or packaging.

7.1. Introduction

Preservation of fruit and vegetables by application of heat is one of the important methods of food preservation as it not only imparts desirable effect in the eating quality of the food but also exerts a preservative effect on the foods by destruction of micro-organisms, enzymes, insects and parasites. Other advantages of heat processing include destruction of anti nutritional factors (e.g. trypsin inhibitor in some legumes), improvement in availability of some nutrients (eg improved digestibility of proteins, gelatinization of starches, and release of bound niacin), production of shelf-stable foods that do not require refrigeration and above all it offers a relatively simple control of processing conditions. The disadvantages of heat processing include alteration or destruction of sensory quality of foods like flavor, colour, taste and texture as a result the heat processed foods are perceived to have different quality as compared to fresh produce.

8.1. Introduction

The term canning refers to a process which involves heating food stuff in hermetically sealed containers for a specific time at specific temperature to eliminate microbial pathogens that endanger public health and micro-organisms as well as enzymes that deteriorate food during storage. The canning of fruits and vegetables is canned out in the season when they are available in plenty. The canned products are then sold in the off season for getting better returns and to assure availability of fruits and vegetables throughout the year at reasonable prices.

8.2. History of canning

Important historical developments in canning are as under:

• The credit for invention of canning goes to Nicholas Appert, a French confectioner who was awarded a prize in 1809 by the French government for developing new method of heat preservation of food in sealed container and after whose name the process of canning is known as Appertization.

• In year 1810, Appert published the first book on canning entitled The Art of Preserving Animal and vegetable substances for many years which is the first known work on canning.

• The work of Appert consists of packing food in glass bottles, closing with corks and heating the container in boiling water for several minutes depending upon type of food.

9.1. Introduction

Fruit juice and beverages generally comprise of naturally extracted juices, drinks, ready to serve (RTS) beverages, nectars, squashes, cordials and appetizers etc. These products are highly refreshing, thirst quenching, appetizing and nutritionally superior to many synthetic and aerated drinks. Fruit juice is the natural liquid expressed by pressure or other mechanical means from the edible portion of the fruit. Fruit juices are generally extracted from fruits in a number of ways, depending on their structure and composition.

The composition of juice is unaltered during preparation and preservation while for fruit beverages like drinks, squashes, cordial etc the fruit juice or pulp, sugar, acid, colour, flavour etc are mixed in appropriate proportions to a desirable taste. Apple juice, orange juice, mango squash, guava drink, pineapple juice and squash, mixed fruit drink, mango nectar etc are the commercial products available in the market.

10.1. Introduction

Sugar acts as a preservative by osmosis and sugar is not a true poison fo micro organisms. It absorbs most of the available water and restricts the availability of water/moisture required for growth of micro-organism. The concentration of 68 70% sugar is used for preparation of jam and jellies. Sugar adds value to these products as it imparts sweetness as well as body to these products. When sugar is boiled with acid and fruits it is hydrolyzed into dextrose and fructose, the degree of inversion depending on the pH and duration of boiling. Because of inversion of sucrose, a mixture of sucrose, glucose and fructose are found in jams and jellies.

Jams, jellies and marmalades constitute an important class of preserved fruit products. Apple jam, pineapple jam, strawberry jam and mixed fruit jam prepared by using pulp of two or more fruits are quite common. Similarly, guava jelly and orange marmalade are also examples of such products.

11.1. Introduction

A fruit preserve is a product made from properly matured fruit by cooking it whole or in the form of large pieces in heavy sugar syrup, till it becomes tender and transparent. A fruit impregnated with cane sugar and glucose, followed by subsequent draining and drying is called a candied fruit e.g. petha candy, ginger candy. Further, candied fruit covered or coated with a thin transparent coating of sugar, which imparts a glossy appearance is referred to as a glaced fruit. When candied fruit is coated with sugar crystals either by rolling it in powdered sugar or by allowing the sugar crystals from glucose syrup to deposit on it, it becomes a crystallized fruit. The use of high concentration of sugar in these products acts as the preservative. The products like Petha candy, aonla preserve, apple rings; candied citrus peels, ginger candy, ginger in syrup; bael, pineapple and carrot preserve are the commercial products in this category.

12.1. Introduction

Drying refers to the method of removal of moisture content from the food to a level at which the activities of food spoilage and food poisoning micro-organism are inhibited. Drying under open sun is probably the oldest method of food preservation used for agricultural crops including food grains, oilseeds as well as fruits and vegetables. Most of the fruits and vegetables contain enough moisture to permit the activity of enzymes and micro-organisms for spoilage and drying is necessary to reduce the water activity. Therefore, reduction in water activity of the food is the main principle of preservation by drying. Two commonly used terms for dried foods are low moisture foods and intermediate moisture foods (IMF). During drying, a single layer of fruit and vegetables, either whole or sliced after primary pretreatments is spread on trays which are placed inside the dehydrator or in the open sun for drying. In mechanical dehydrator, the initial temperature is generally kept at 43oC which is then gradually increased to 60-66oC for vegetables and 66-71oC for fruits.

13.1. Introduction

The preservation by using common salt, spices and vinegar is a common method for preparation of pickles, sauce and chutneys. Salt is mostly used as preservative in pickles in combination with acid. Minimum concentration of salt to act as preservative is about 12%. It inhibits enzymatic browning/discoloration by acting as an anti-oxidant. It exerts its preservative action by:

• Causing high osmotic pressure and thus suppress the microbial cells.

• Dehydrating food by tying up the moisture thus making it unavailable for the growth of microorganisms.

• Salt in the food affects the solubility of oxygen and thus growth of aerobic microorganisms is inhibited

• Chlorine in sodium chloride being good oxidizing agent is toxic to microorganisms

• Salt increases the permeability of the cell wall and thus cause changes in the permeability. Only the haloduric microorganisms can tolerate these effects while others are unable to survive.

• Similarly addition of acid to the food lowers the pH of the food which inhibits the growth of spoilage causing microorganisms.

• Addition of spices and edible oil in these products besides improving flavour and taste also help in preservation.

14.1. Introduction

Tomato is grown in India in abundance both in summer and winters. Tomato though botanically a fruit is generally considered as vegetable because of the way in which it is consumed. Fresh tomatoes are very refreshing and appetizing but can not be stored for a long period. During peak season, about 25% of the produce is spoiled due to mishandling and such losses can be avoided by converting tomatoes into different value added products. Tomato can be processed into pulp, paste, puree, juice, ketchup and sauce. In India, tomato sauce and ketchup are very popular. High quality products can be prepared from tomatoes by:

1. Using uniformly ripened, red coloured tomatoes.

2. Avoid prolonged heating and cool the product immediately after cooking.

3. Avoid using iron and copper equipments and utensils at any stage of processing.

15.1. Introduction

Freezing is one of the oldest and most widely used methods of food preservation, which allows preservation of taste, texture, and nutritional quality in foods better than any other method. It is a process of bringing down the temperature of food below its freezing point and the frozen storage generally refers at temperature below -18oC.

15.2. Theory of freezing

The freezing process is a combination of the beneficial effects of low temperatures at which micro-organisms cannot grow, chemical reactions are reduced, and cellular metabolic reactions are delayed. Freezing is generally referred to as a unit operation in which the temperature of food is reduced below freezing point and a proportion of water undergoes a change in state to form ice-crystals. Immobilisation of water to ice and the resulting concentration of dissolved solutes in unfrozen water cause lowering of water activity of the food. Thus reduction in water activity and use of low temperature coupled with some pre- treatments like blanching is the basis for food preservation by freezing. Fruits such as strawberries, oranges, raspberries, black currants and vegetables like green pea, green beans, sweet corn, spinach, sprouts and potatoes are examples of commercially frozen products.

16.1. Introduction

Plantation crops are high value industrial crops grown in the tropics play a vital role in agricultural economy and export trade of developing countries. Plantation crops have great potential for utilization of waste land like rainfed dry land, hilly, arid and coastal areas to provide nutritional security, earn foreign exchange and to ensure livelihood security. The major plantation crops grown in India are tea (Camellia sinensis L), coffee (Coffea arabica L.), rubber (Hevea brasiliensis), coconut (Cocos nucifera), arecanut (Areca catechu L.), oilpalm (Elaeis guinensis), cashewnut (Anacardium occidentale L.), cocoa (Theobroma cacao L.) and cardamom (Elettaria cardamomum). India is the leading producer of most of these plantation crops. Among all fruit crops, the processing plays an important role in plantation crops as they are generally consumed only after processing. In addition to primary products which are exported largely, some by-products from these crops also have industrial as well as commercial uses. Coconut, arecanut, cashewnut, black pepper and cardamom are known as small holder plantations whereas, crops like rubber, tea and coffee are known as estate crops or conventional plantation crop. Coir, wood and shell from coconut, leaf sheath in arecanut, cashew nut shell liquid (CNSL) and feni from cashew are some of by-products with a great impact and demand in the market.

17.1. Introduction

Tea (Camellia sinensis L), coffee (Coffea arabica L.) and rubber (Hevea brasiliensis) are known as estate crops or conventional plantation crops. These plantation crops are perennial in nature and cultivation of these crops generates considerable employment opportunities during on farm and off farm processing activities. The plantation crops are high value industrial crops contributing about 25% of AGDP. India is a largest consumer of tea accounts for 22% global tea consumption and also accounts for one-fifth of global tea area. Indian coffee industry also have prime place among plantation crops and also contributing 4% coffee to global market. Similarly, rubber plantations also provides basic raw material to toys, balloon, tyres, seed oil cake and rubber wood factory. The plantation crops along with main processed products also produce large quantity of biomass like husk, coir dust, coffee husk, tea waste, shedding etc which can effectively used to reduce nutrient requirements of crops. Parchment coffee prepared by using the wet method is generally favoured by the market. Cherry coffee, due to its very nature of preparation and longer contact with the mucilage and fruit skin, is usually associated with a characteristic fermenting flavour.

18.1. Introduction

Spoiled food is defined as the food that has been damaged or has undergone changes so as to render it undesirable/unacceptable/unfit for human consumption. Spoilage of processed products is mainly caused by the action of micro-organisms and due to the physical or chemical changes. The reasons for microbial spoilage include under- processing, inadequate cooling, contamination from leakage through can seams and pre-process spoilage. In under-processed cans (receiving low heat treatment) large number of micro-organisms is expected to be involved in spoilage.

18.2. Causes of food spoilage

Food spoilage or deterioration may be described as loss of weight, softening, souring, rotting, wilting, moulding or a combination of one or more forms. The major causes of food deterioration are: biotic and abiotic factors.