eChapters

Summary

Fertilizers are materials when applied replenish lost soil nutrients on farmer’s field. Without the use of fertilizers farmers would find it extremely difficult to increase their production to meet the ever-growing mouths. The purpose of this session is to discuss what a fertilizer is, and the different terminologies used in fertilizer technology.

Summary

ISFM is important, cost-effective and has the potential of improving farming efficiency and crop productivity. This is only possible when farmers understand the concept and follow recommended practices in the ISFM approach.
 
The challenge is how to effectively disseminate ISFM practices to farmers for sustainable crop production.

Summary

Food production starts with a good soil. No matter the kind of seed and good agronomic practices that are put in place without a good soil yields will be low and hence income. ISFM is a technology that helps to solve the problem of soil infertility and production.
 
Farmers only accept and adopt a technology if they see it to be superior to what they have been doing and it makes business sense. Farmers will not worry about the bigger picture of food security or increased production – they need to make a profit to support their household.

Summary

Reaching large-scale implementation should be the overriding objective of all projects that have successfully ISFM practices to share provide markets support them. All too often ISFM results are only reported in peer-reviewed journals that are not accessible outside the research community.
 
Funding agencies often fail to make the production of extension materials an integral and mandatory requirement of research projects.
Unfortunately, in the past, adoption of economically proven technology has often been poor. Some of the reasons include:

Abstract

Cyanobacteria have gained a lot of attention in recent years because of their novel applications in biotechnology, besides their well recognized role as inoculants for rice crop. They represent favourite model organisms for a deeper understanding of several plant and microbial metabolic processes and efficient systems for the production of recombinant compounds of pharmaceutical and commercial value. They have been identified as a rich source of biologically active compounds with antiviral, antibacterial, antifungal and anticancer activities, which illustrate their potential as biocontrol agents. The genus Anabaena assumes significance not only as a diazotroph, but also as a rich source of pharmacologically active and structurally interesting secondary metabolites with diverse applications in agriculture and industry. The present compilation aims to present an overview of the literature available globally, and studies undertaken in India illustrating the diversity and potential of Anabaena strains, besides their significance in biology and evolution.

Abstract

Twelve different cyanobacteria strains from different locations in Syria were collected and analyzed. They were identified as strains from Anabaena, Nostoc, Phormidium and Chroococcus. All strains produce mycosporine-like amino acids (MAAs) as UV-screens upon UV-radiation. Composition of the MAAs and amount of UV-induced MAA production differ between the strains. In order to evaluate the long-term stability of completely encapsulated cyanobacteria aliquots were transferred into hermetically closed vessels. The survival was non-invasively determined by means of pulse-amplitude modulated fluorescence and by delayed fluorescence detection. It was found that 4 strains (one Chroococcus, two Anabaena and one Nostoc species) show photosynthetic performance after 4 years of encapsulation. In addition, many cyanobacteria are desiccation tolerant and are able to fix atmospheric nitrogen. They may play an important role in biological life support systems e.g. in space research.

Abstract

Present implementation of mass spectrometers has allowed developing new approaches in algal research. Soft ionization techniques like atmospheric pressure chemical ionization (APCI), electrospray ionization (ESI), and matrix assisted laser desorption ionization (MALDI) extend the analytical possibilities of mass spectrometry (MS) beyond classical fatty acid analysis by gas chromatography (GC) with electron impact ionization (EI). New MS-based analytical methods have been developed over the last two decades for algal molecule research including membrane lipids, carotenoids, mycosporine-like amino acids and peptides.
 
MS-based Metabololomics approaches have also been used to gain insights into algal biochemistry and physiology. This review aims at highlighting the achievements in algal research gained by using these recent research tools and their future prospects.

Abstract

Being an obligate photoautotroph, cyanobacteria must cope with a wide range of fluctuating environmental factors, including high light and ultraviolet radiation (UVR) that may lead to oxidative stress by upsetting the cellular redox status. Photo-induced oxidative stress by means of oxidizing agent such as reactive oxygen species (ROS) may damage several biological processes. In response to several adverse effects of solar UVR, cyanobacteria have developed different strategies such as heat dissipation mechanisms, synthesis of UV- absorbing/screening compounds and antioxidant systems to overcome the detrimental effects of intracellular oxidant molecules. This review deals with UV-induced oxidative stress and their counteracting mechanisms operating in cyanobacteria.

Abstract

The substantial loss in the shielding ozone layer has resulted in an increase in the solar ultraviolet radiation (UVR) on the Earth’s surface, which is detrimental for all living organisms ranging from prokaryotes to eukaryotes, including humans. This has augmented the scientific concern and interest in searching for the photoprotective compounds from diverse organisms. Cyanobacteria, the primitive O2-evolving photosynthetic prokaryotes are solely dependent upon the solar radiation for their energy requirement and thereby have to always face the UV-B stress. UVR affects cyanobacteria either directly or indirectly by inducing oxidative stress. In response, they have evolved the capacity to synthesize, accumulate and metabolize a variety of UV-absorbing compounds such as, mycosporine-like amino acids (MAAs), scytonemin, carotenoids, biopterin glucoside, as a strategy to reduce the direct and indirect damaging effects of UVR.

Abstract

Synonymous and non-synonymous substitution result in isomerization and deformity in protein structure. Both play more or less important role in evolution. Interestingly, cyanobacterial phycobiliproteins (PBPs) are composed of proteins which are coded by codons by mRNA translation. These proteins are categorized into three groups e.g., C-PC, C-PE and C-APC having a and b subunits. The skeleton and arrangement of amino acids in subunits can provide structural and functional integrity of PBPs as well as GC₃ associated substitution of synonymous and non-synonymous codons.

Abstract

Cyanobacteria, the Gram-negative photosynthetic prokaryotes are able to produce a wide range of secondary metabolites. Some of these metabolites are of general concern due to their toxicity and known as cyanobacterial toxins. These cyanotoxins are reported widely due to human and animal health hazard. On the basis of their toxicological target, these cyanotoxins can be classified into five different groups: hepatotoxins, neurotoxins, cytotoxins, dermatotoxins and irritant toxins (lipopolysaccharides). Hepatotoxins constitute a family of cyclic peptide variants and are classified as microcystins and nodularins. These hepatotoxic peptides possess a high degree of cellular specificity to the hepatocytes with similar mode of action and act as potent inhibitors of protein phosphatases 1 and 2A (PP1 and PP2A).

Abstract

The extensive use of antibiotics has raised serious health concern throughout the world due to development of resistance in microbes towards many classes of antibiotics. The emergence of multidrug resistance (MDR) in microbes and lack of novel classes of antimicrobial agents have raised an immediate need to identify new agents with novel mode of action. In addition to novel agents, inhibitors of efflux pumps are being now viewed as one of the most viable management strategy for treating MDR infections. In this concern, plants have always been a source of inspiration for novel drugs.

Abstract

Despite several controversies surrounding the genetically modified (GM) crops or their produce, the production of such crops is constantly increasing, especially in developing countries. To regulate the GM produce in the market, several countries have set very strict regulatory procedures for the approval to grow, import or utilize these GM crops as food or food ingredients. Hence, for regulatory compliance on GM labeling and identification of genetic traits, the development of reliable, sensitive and precise detection assays have become essential. The detection of GM produce is carried out by detecting either the inserted foreign DNA or the novel transgenic protein specifically expressed in GM crops. This article broadly focuses on some DNA and protein-based detection methods employed for GM produce and significant current advances in such detection technologies.

Abstract

Cyanobacteria were first oxygen evolving photosynthetic organisms on Earth, which not only survived under harsh conditions of primitive Earth but are also dominant and efficient photosynthesizers and N₂ fixers of present time which significantly contribute to fertility of paddy fields as natural biofertilizers. Cyanobacteria require solar radiation to carry out photosynthesis and nitrogen fixation. The stratospheric ozone depletion which has resulted in an increase in ultraviolet-B (UV-B; 280 - 315 nm) radiation on the Earth’s surface has been reported to inhibit a number of photochemical and photobiological processes in cyanobacteria. However, they have evolved mechanisms such as synthesis of photoprotective compound scytonemin and their derivatives to counteract the damaging effects of UV-B. In addition to Photoprotection, scytonemin has biotechnological potentials and several applications in biology and allied sciences.

Abstract

This study was conducted to examine the response of photosynthetic pigments to heavy metal stress in a short-term toxicity test using high performance liquid chromatography (HPLC). HPLC pigment analysis of Euglena has resulted in 5 separated pigments: chlorophylls a, b and three carotenoids, which are 9-cis-neoxanthin, diadinoxanthin and b-carotene.

Abstract

In order to fill the gap between the protein sequences and their 3D structures available in the public databases, the computational prediction of protein structure has become the need of the hour. Therefore, the present chapter aims to highlight various methods and strategies for computational protein structure prediction by established ab initio, threading and homology modeling methods. Ab initio, threading and homology modeling methods are mainly based on the low sequence similarity, similarity between 25-30% and similarity more than 30% with the template structure respectively. Hybrid methods are preferred which club together a number of features such as structural alignments, solvent accessibility and secondary structure informations.

Abstract

A transect was performed along the Chubut River (Patagonia) from the Atlantic towards the Andes measuring major water parameters of this drainage area. Samples were taken at different locations of the Chubut River, and also brooks several Andes lakes in the Chubut and Río Negro Provinces as well as from several Andes rivers and mountain creeks. For comparison, the Laguna Cacique Chiquichano in Trelew (Chubut) was investigated. Several physico-chemical parameters were determined (pH, oxygen, nitrogen compounds, conductivity, redox potential, water hardness and spectral transmission), as well as photosynthesis by means of PAM fluorimetry. Water toxicity was assessed with a bioassay based on toxicity-induced changes of the movement behavior of a flagellate.

Abstract

Cyanobacteria  evolved during  the  Precambrian  era and are believed to be the first  one  to  introduce oxygen  into  the  initially  reducing  atmosphere  by  oxygenic  photosynthesis. Thus being the main primary producers of organic matter at that time and thereby contributed to a major global transformation leading to the development of aerobic metabolism and the subsequent rise of higher plants and animal forms. Reactive  oxygen  species  (ROS)  in  cyanobacteria  are  commonly  generated during  normal  growth  and  development.  However  abiotic  and  biotic stresses  enhance  the  level  of   ROS  which  in  turn  pose  the  danger  of oxidative  stress.  Ability  to  perceive  ROS  and  to  rapidly  initiate  antioxidant defenses  is  crucial  for  their  survival.  Therefore cyanobacteria evolved four lines of defense mechanisms to combat the damages caused by oxidative stress. Inretrospect  to  their  ecological  adaptivity, ubiquitous  presence  and  efficient  source  of   compounds  of biotechnological  significance, this chapter aims to elucidate various mechanisms adopted by cyanobacteria to combat oxidative stress.

Mycorrhiza research is relatively recent. Although, it was in 1885 that A.B. Frank made reference for the first time to the term “Mycorrhiza”, it took him nine more years to establish the symbiotic relationship between the fungus and its host plant. It took a much longer time to convince the rest of the scientific community of the validity of Frank’s theory. Researches carried out between 1917 to 1950 confirmed that “Mycorrhizal colonization is a beneficial symbiosis between tree and fungus”. It is an unique partnership in nature, where the higher plants share their photosynthates with their fungal partners and provide them shelter, the fungal partners in return provide protection to the root system and assist it in performing its functions especially anchorage and absorption of nutrients / water from soil more efficiently.

The ectomycorrhizal fungi have been in use as a biological tool in improving the performance of forest trees since long. Better performance of forest trees is ensured by making them mycorrhizal, employing efficient strains of ectomycorrhizal fungi.

VAM fungi are of worldwide distribution. They are present in the soil in form of chlamydospores, zygospores and azygospores and have been recovered from the soils of a variety of habitats e.g. agricultural fields, nutrient deficient soils, sand dunes and deserts, industrial wastes, sodic soils, polluted sites, sewage, eroded sites and others like forests, open woodlands, scrub, savana, heaths, grasslands, anthracite and bituminous coal wastes. There are several reports of VAM fungi from diverse habitats from India.

VA-mycorrhizal associations occur widely throughout the plant kingdom. They have  been reported to be present in Bryophytes, Pteridophytes, Gymnosperms and Angiosperms in nearly all the geographical regions of the world. Most of the agricultural and horticultural crops belonging to diverse families have been shown to form VA-mycorrhizae. Many species of plants of economically important families have been reported to be mycorrhizal. Likewise, many of the plantation crops like coffee, tea, citrus, timber trees, many of the fruit trees and medicinal plants have been shown to form VA-mycorrhiza.

In recent years the importance of VAM fungi for plant growth in most soils has been accepted and acknowledged by soil chemists, agronomists, horticulturists and farmers. Ever since it was shown that VAM could increase nutrient uptake and water uptake from soil in plants, researchers have been trying to extend and manipulate this effect of mycorrhiza in improving the growth and productivity in various groups of plants. Mycorrhizasts of the country have also explored the possibility of utilizing this tool for improving the performance of various crops including cereals, millets, pulses, vegetables, oilseeds and fruit crops. In addition, they have tried to explore the possibility of utilizing this biotool also for improving the growth of various types of trees including forest trees. Following account is related to the work done by the mycorrhizasts of the country on the effect of VA mycorrhiza on the growth and productivity of various groups of plants including cultivated crops.

Favourable effect of VAM association in plants has been attributed to an increased nutrient uptake by mycorrhizal roots. The transfer of ion from the soil to the roots by mass flow or by diffusion depends on the mobility of that particular ion in the soil. Ions such as NO₃^- ,SO ₄^— and Ca⁺⁺ may move rapidly through the soil to the roots by mass flow, and uptake would be limited by the absorbing capacity of the roots. On the other hand, ions such as H₂PO₄^-, NH₄⁺, Zn⁺⁺ and Cu⁺⁺ are poorly mobile and move to the roots by diffusion, the rate limiting steps is likely to be the movement to the root surface. Under such conditions, it is expected that uptake would be increased if ions could be moved rapidly through extramatrical hyphae of the VAM fungi rather than diffusing slowly through the soil. It is now well established that VA mycorrhizae enhance the uptake of phosphate by the roots but it is likely that they can also assist in the uptake of other ions. The following account provides an information on the findings of Indian mycorrhizasts on the effects of VA mycorrhizal association on nutrient uptake in the plants and its physiological implications.

Of the various microorganisms present in and around roots, VAM fungi occupy unique ecological position as they are partly inside and partly outside the host. Their internal phase encounters competition and antagonism from other beneficial symbiotic microbes while their external phase faces competition and antagonism from beneficial non-symbiotic microbes present around the roots. Since they have an ensured source of nutrients from the host, they have comparatively better conditions for their growth and may exert greater effect on plants with other symbiotic and non-symbiotic microbes in and around their roots. It has been pointed out that investigations are needed on the interactions between VAM fungi and these beneficial microbes, and their effect on growth and productivity in plants. A bulk of information has been collected related to this aspect; however, authentic generalization has not been possible as yet. Following description gives an account of the work done by Indian mycorrhizasts on the interactions between VAM fungi and other beneficial symbiotic/non-symbiotic microbes in and around the roots.

Factors which influence the colonization and life cycle of VAM fungi have important bearing on the extent to which they may benefit their host. As we move closer to using mycorrhizal fungi to increase growth and productivity of different plant communities, a thorough understanding of the factors which influence their survival, germination, root colonization an d sporulation will be critical. Seasons, physico-chemical characters of the soil, agronomic practices, plant protection chemicals, pollutants and genotypic characters of the host may affect VAM fungi and their potentiality to colonize and provide benefit to the host. In view of this, the effect of such factors on the VA mycorrhizal symbiosis and its benefit to diverse plant communities has been extensively investigated worldover.

Extensive studies have been carried out to explore the possibility of using mycorrhizal model system in inducing suppressions of potential soil-borne pathogens. Its relevance becomes all the more important since most of the soil-borne diseases, by and large, are not easily controlled by conventional methods.

Diseases due to Fungal Pathogens

Most of the studies conducted on the interaction of VAM fungi and fungal pathogens suggest that mycorrhizae decrease the severity of disease, while a few studies suggest that there is either no effect or there is an increase in the severity of disease. It has been pointed out that in view of the fact that VAM fungi deter the severity of disease they may be used as biocontrol agents. Various mechanisms by which VAM could suppress the fungal pathogens have been suggested on the basis of experimental evidences.

During the last thirty years, there has been a growing appreciation of the impor tance of VAM fungi in improving the plant growth and yield. They have been extensively studied also in India. Considering the potential importance of these organisms in the recovery of disturbed sites and their possible use in land reclamation, researches regarding their relationship to ecosystem recovery have now been initiated also in India.

Large areas of land in the country called wastelands are degraded and lying unutilized due to various constraints. Part of it called culturable, has the potential for the development of vegetation cover. On the other hand, part of it called unculturable, has no potential for the development of vegetation cover. In addition to these natural wastelands, there are large tracts of wastelands created due to human activities such as mining, deforestation etc. Such wastelands are also culturable and a vegetation cover can be developed on them after removing the constraints with some efforts.

Since a method to cultivate VAM fungi in pure culture is not available as yet, clean and high quality VAM inoculum production is not possible. However, VAM technology is gradually getting a place in agriculture as well as reclamation and afforestation programmes. The inoculum currently being used includes infested fields soils, sievings from such soils, soil and roots of greenhouse plants, or pot culture inoculum derived from surface disinfected spores of a single VAM fungus on a host plant grown in a sterilized growth medium. Attempts are being made to manipulate VAM fungi, rooting media, hosts and fertilizers in order to secure superior quality of inoculum by these methods on a large scale. In addition, other techniques like tissue culture, hydroponic system etc. are also being attempted to cultivate VAM fungi in pure culture. The Indian mycorrhizasts have also attempted to devise and develop improved methods for production and storage of commercial VAM inoculum. The following description gives an account of Indian work related to production and storage of consistently high quality disease free VAM inoculum.

The understanding of VAM symbiont and VAM symbiosis is of prime importance in manipulating VAM associations for the welfare of plants. Many contributions have been made worldover in the areas of taxonomy, morphology, anatomy, histology, cytology and genetics of VAM fungi and/or their associations with the plants. However, the share of Indian mycorrhizasts in such contributions is negligible. The following description gives an account of work done by the mycorrhizasts of the country in these areas.

Current status of researches on VA mycorrhiza and their benefits to the plants carried out by the mycorrhizasts of the country has been described in detail in chapters II to X.

Prior to the establishment of any specific forum, the pace of research on VA mycorrhiza in the country was not of desired level. However, the activities related to research on VA mycorrhiza gained unexpected momemtum when Mycorrhiza network came into exixtence in the year 1989. The network provided not only assistance and guidance of various types to the scientists working on VA mycorrhiza in the country but also offered them periodical platforms to exchange their informations and thoughts on status of researches on VA mycorrhiza and to propose future strategies of research. During the National conferences held in different parts of the country the panel of experts made certain observations regarding future prospects and strategies for research on VA mycorrhiza. They have been mentioned in the present chapter.

Introduction

Water is a precious natural resource vital, for sustaining all life on the earth. It is in a continuous circulatory movement - hydrologic cycle. It is not uniformly distributed in time and space. Due to its multiple benefits and the problems created by its excesses, shortages and quality deterioration, water as a resource requires special attention. On a global scale, total quantity of water available is about 1600 million cubic km. The hydrological cycle moves enormous quantities of water about the globe. However, much of the world’s water has little potential for human use because 97.5% of all water on earth is saline water. Out of remaining 2.5% fresh water, most of which lies deep and frozen in Antarctica and Greenland, only about 0.26% flows in rivers, lakes and in the soils and shallow aquifers which can be readily used. Sustainable water management in India is fast becoming a necessity, with the looming crisis over water resources in the country threatening the security and livelihood of the population and the environment over the coming decades. Managing water resources, river catchments, and coastal zones are outstanding challenges of today and tomorrow’s. Global changes ask for a comprehensive scientific approach, an international multi-disciplinary orientation and require a new mind-set towards water and coastal management problems.

Introduction

The globally growing demand for water has ushered the need for its efficient and judicial utilizations in all fields, and agriculture in particular being a single largest consumer of water. The majority of irrigation projects in India perform at a very low efficiency, which calls for application of efficient water management technologies for meeting the increasing water demands. Estimation of soil moisture or crop evapotranspiration from climatic parameters provides objective criteria for irrigation management. Methods to estimate evapotranspiration require huge climatic data, which are seldom available and not applied by common crop growers. Determining crop water requirement through soil moisture measurement at several locations is time consuming, destructive exercise, and may not give proper assessment of crop water need. The plant based indicator approach considers the plant water status for scheduling irrigation. This might be considered as the ideal criterion because the plant water is a good integrator of the soil, water and climatic parameters.

Introduction

Indian agriculture was contributing 70% to total GDP of the country at pre-independent time, but it decreased drastically year by year and contributed 66.8% in 1960, 55.6% in 1994, 27.1% in 1997 and now a days, it reached only to 25% in 2001. With the advancement of civilization our population is increased, whereas, the cultivable lands is decreased side by side, thus, on an average income of agriculture is decreased.

Gujarat is the leading state to concern with the productivity, production and the area of the some crops like Groundnut, Castor, Cotton, etc. in India. The major part of the state is surrounded by sea coast border, which is 1600 km. Gujarat is popular for production of oilseed crops like groundnut, cotton ; horticultural crops like mango, chiku, coconut, banana, papaya, citrus; spices crops like chili, cumin, funnel etc.

The coastal agro ecosystem is very important among the different agro ecosystems of our country both economically and environmentally. It spans over a length of 8129 sq. km. covering 9 states and 2 Island ecosystems. Agriculture and allied activities constitute the single largest component of India’s economy, contributing nearly 27 per cent of the total Gross Domestic Product (GDP) in the year 1999-2000 (TERI, 2002). Agriculture exports accounts for 13 to 18 per cent of total annual exports of the country (MoF, 2002). However, given that 62 per cent of the cropped area is still dependent on rainfall (MoEF, 2002). Coastal agricultural region comprises of hinterland, which has a varied geometric and topographical features of mountains valley, coastal plains, riverine systems, climatic conditions, different soils and water bodies, vegetation ranging from rich tropical rain forests to coastal mangroves and a wide range of crops that are cultivated in this region (Table 1). The agro climatic conditions of the coastal zones are congenial for growing various field and horticultural crops.

Experiment

An experiment is a planned inquiry to obtain new facts or confirm or deny the result of previous experiment. Such inquiry can aid in an administrative decision, such as recommending a variety, a feed, a cultural practices, a fertilizer, a pesticide or a fungicide etc.

Type of Experiments

    1.     Preliminary experiments : Here investigator tries out large number of treatments in order to obtain leads for future work. Here replications are not taken for such treatments tried e.g. number of pesticides for control of diseases - take single observation for each treatment and take decision that some of them worth trying for use.

Groundwater is a precious renewable resource which gets replenishment from the precipitation. Total water resources of the world are estimated at 1.37 x 10⁸ million ha-m. Of these, about 97.2% is salt water, mainly in oceans, and only 2.8% is available as fresh water. And, out of this 2.8%, about 2.2% is available as surface water (2.1% is fresh water in glaciers and icecaps, 0.1% is available in lakes and reservoirs, 0.0001% in streams) and 0.6% is available as groundwater. Only 50% of groundwater resource is economically extracted with available technology. Presently, 1.3 x 10⁴ million ha-m fresh water in reservoirs and 41.1x10⁴ million ha-m groundwater is theoretically available to provide usable water for drinking, domestic use, irrigation, etc., to mankind. Groundwater is the largest source of fresh water excluding the polar icecaps and glaciers. The amount of groundwater within 800 m from the ground surface is over 30 times the amount in all fresh water lakes and reservoirs, and about 3000 times the amount in stream channels, at any one time.

Aquaculture is the cultivation of fish, molluscs, crustaceans (shell fish) and aquatic plants in controlled conditions, provides an increasingly significant proportion of food production globally. The sector has represented the greatest growth of all food production systems in the last two decades and an estimated 10% yearly increase in output is likely to bring productivity to a predicted 47 million tonnes in the year 2010 (Pedini and Shehadeh, 1997). Significantly, the greatest contribution to total production and the greatest rate of uptake of aquaculture activity is in the developing world. More than 82% of the total global yield in 1999 was produced by developing countries (GESAMP, 2000) and growth rates between 1984 and 1995 were six times higher than that from developed countries (Rana, 1997; Tacon, 1996).

Soil Erosion As a Process
 
Soil erosion is a three stage process, namely (1) detachment, (2) transport, and (3) deposition of soil. Different energy source agents determine different types of erosion. There are four principal sources of energy: physical, such as wind and water, gravity, chemical reactions and anthropogenic, such as tillage. Soil erosion begins with detachment, which is caused by break down of aggregates by raindrop impact, sheering or drag force of water and wind. Detached particles are transported by flowing water (over-land flow and inter-flow) and wind, and deposited when the velocity of water or wind decreases by the effect of slope or ground cover. Processes like dispersion, compaction and crusting, accelerate the natural rate of soil erosion. These processes decrease structural stability, reduce soil strength, exacerbate erodibility and accentuate susceptibility to transport by overland flow, interflow, wind or gravity. These processes are accentuated by soil disturbance (by tillage, vehicular traffic), lack of ground cover (bare fallow, residue removal or burning) and harsh climate (high rainfall intensity and wind velocity).

Introduction

Salinity in India is a major issue affecting the sustainability of irrigated as well as non-irrigated areas particularly in the states of Rajasthan, Gujarat, Haryana, Uttar Pradesh, West Bengal and Orissa. Salt affected soils are unproductive unless excess salts are reduced or removed. These soils occur most extensively in arid and semi-arid climates, but these soils are also found in coastal sea areas where soils are unundated by ocean or sea water. Soils are said to be saline if they contain an excess of soluble salts and sodic or alkali if they contain an excess of sodium salts. Again soils are said to be saline-sodic or saline-alkali if they contain appreciable amounts of both soluble salts and sodium. The impact of salinity manifests itself in several ways. As the salinity increases, not only does the productivity decline but sensitive crops also go out of cultivation and are replaced by salt-tolerant, low value crops and other plant species.

Mulching

The technique of covering the soil with plastic films or natural crop left over (residues) for soil and water conservations is called mulching.

This technique was practiced by farmers using dry leaves straw, trash, stones etc to conserve water. Presently plastic film have come into use for the purpose of mulching due to inherent advantages.

India is an agricultural country. The geographical area of India is about 328 mha out of which 147 mha of land under cultivation and 84-mha land is under irrigation. The population is increasing at an alarming rate that requires producing more food for the growing population. This problem can be solved either by increasing the land under irrigation or using different soil water conservation techniques. It is well known fact that during rainfall a considerable amount of water goes to sea due to high rate of runoff. It is highly needed to trap as much as water falling in the form of rainfall and recharge the groundwater so that it is made available for irrigation purposes.

Agricultural land drainage is adopted for removal of excess surface and subsurface water, either from irrigation or rainfall in order to improve the profitability of land use.  Drainage also plays a role in removal of salts from the root zone. Therefore, land drainage is closely linked to irrigation in arid and semi arid regions. India has a long history of practicing irrigation and drainage in its semi arid irrigated regions. During the ancient times in the Indus Valley dams and drainage system were built for cultivation of different crops. The earlier experience of drainage was more concerned with surface drainage because from time immemorial India has been experiencing floods of varying magnitudes.

For better yield irrigation water must be free from soluble salts and from concentration of specific chemical substances that may hazard to soil with respect to salinity, sodicity, alkalinity and toxicity. Water analytical data which helpful to predict the magnitude of the effect of irrigation water on soil and plant growth under specific environmental circumstances so irrigation water must be analyzed for EC, pH, Na+, Ca⁺⁺, Mg⁺⁺, Cl^-, CO₃–, HCO₃-  and SO₄.^– 

Importance

Drought is a climatic anomaly characterized by deficient supply of moisture, which may result from sub-normal, untimely and unevenly distributed rainfall. Among the various hazards of nature, drought is one of the major disasters because it brings innumerable miseries to the mankind. Almost every year some part or the other of the country suffers from such calamities. Drought is a recurring phenomena and its occurrence cannot be avoided. However, its impact can be minimized through application of science and technology by developing drought management plans.

The Gujarat state is located on the north-west of India between 20^o6' N and 24^o42' N latitude and 60^o24' E to 74^o24' longitude. The climate of Gujarat is semi-arid tropical . the summers are very hot, the winter season is uncertain and irregular. The Arabian sea and Gulf of cambay have a moderating effect on the climate of the coastal areas of the state.

The state has a coastline of 1600 km (27% of the country) out of which Saurashtra and Kutch has about 1125 km long coastal line. The total coastal cropped area of the state is 8.75 lakh ha (9.11% of total cultivated area) spread over three agro-climatic regions of the state, out of which 91% comes under arid and semiarid climate type (Table 1). The important crops of the region are groundnut, bajara, sorghum, cotton, and wheat. The ground water availability is also scare. In the state recently the soil degradation through salinity has caught hold over 1.2 m ha of land, of which, about 0.3 m ha occurs in the coastal area. About 1125 km long coastal line is in Saurashtra and Kutch which comprises about 0.1079 m ha of saline land which needs to be treated for salinity reduction.
 

Agriculture is world’s single largest employer and probably the most weather dependent of all human activities.  Climate and its variability have been and continue to be, the principal source of fluctuations in global food production. Throughout history, extreames of heat and cold, droughts and floods, and various form of violent weather have wretched havoc on the global agricultural production. With the unprecedented increase in population over past few decades, clearly the mankind faces undertaking task to ensure food and nutritional security for all, considering reduced per capita land, reduced availability of water, depleting biodiversity and need to preserve ecology and environment. In India, of the total geographical area of 328 m ha, about 175 m ha (53 % of total) are categorized as degraded land, of which 150 m ha are subjected to serious water and wind erosion (Singh et al. 1981). Crops are sown in about 180 m ha annually. Since it seems very much impossible to bring more area under cultivation we need to achieve greater efficiency in the natural resources use while conserving the environment by placing greater emphasis on understanding and exploiting climatic resources for the benefits of agriculture.

Participation means different things to different people. They way participant is defined largely depends upon the context and back ground in which participation is applied. While the Economic Commission for Latin America (1973) considers contribution by the people to public programmes to the complete exclusion of any involvement in the decision making process as participation. Cohem and Uphoff (1977) maintain that participation tools includes the peoples involvement in the entire decision making process. Like Cohem & Uphoff, FAO (1982) emphasizes participation in all the decision making processes but by the people’s organization and through self organized action. Paul (1987) introduces the concept of enhancement of well-being in terms of values cherished by the communities as being the ultimate objective of participation.

Vegetables are defined as edible herbaceous plants or parts of plants consumed as raw or after cooking and are rich in vitamins and minerals, low in calorific value and neutralize the acid substances produced during digestion of high energy foods.  Olericulture is a branch of Horticulture that deals with production, storage, processing and marketing of vegetables and has its origin when man started growing vegetables for consumption. The term Olericulture comes from Latin words holus-holeris = any kind of culinary vegetable, pot herb, and cultura = to cultivate.

Quite a large number of vegetable crops are grown in the country either on a commercial scale or limited to backyards of homesteads.  A few crops have similarity while others have dissimilarity in their climatic and soil requirements, parts used, method of cultivation etc. While describing individual vegetables, there is possibility of repetition in many aspects. In order to avoid repetition, it is essential to classify or group them into different classes/groups. Different methods of classification followed in vegetables are described below: 

Diverse soil and climatic conditions prevailing in different parts of the country offer scope for cultivation of a variety of crops in India.  Around 250 crops either cultivated or grown under natural habitat are used for vegetable purpose.  The crops and varieties vary in their soil and climatic requirements, cultivation practices, resistance to pests and diseases, quality etc.

Considering the climatic conditions for growing vegetable crops and for evolving zone wise technologies and recommendations, the entire country is divided into eight agro-climatic zones under the All India Coordinated  Research Project (Vegetable Crops) as given in Table 1.

Vegetables are grown on a limited scale in homesteads for family use and cultivated in an extensive scale for marketing.  Depending on the purpose for which they are developed, vegetable gardens are classified into different types, viz., kitchen garden or nutrition garden, market garden, truck garden, garden for processing, garden for seed production and vegetable forcing or protected cultivation.