eChapters

ABSTRACT

Commercial propagation using tissue culture techniques started in seventies for orchids in USA. Since then, the science and technology of tissue culture have advanced particularly after the development of the most widely used medium by Murashighe and Skoog (1972). The science has led to the development of the fascinating area of gene transfer. Today, micropropagation protocols are available for almost all horticultural crops. But, there are certain grey areas where research need to be intensified to solve the problems confronting certain difficult to propagate species belonging to plantation and spice sectors. The major area that needs to be addressed is recalcitrance.

ABSTRACT

The Plant Growth Promoting Rhizobacteria (PGPR) is a group of rhizosphere-colonizing bacteria producing substances which increase the growth of plants and/or protect plants against pathogens. The use of PGPR has become rather common practice and is on the rise in many regions of the world. Inoculation with PGPR also aims at reducing the application of potent ially pollut ing chemical fertilisers and pesticides. Biocont rol microorganisms have unquestionable potential for managing plant diseases, insect pests and nematodes besides increasing crop productivity. Interest in biological control has recently been intensified because of imminent bans on effective pesticides, widespread development of pesticide resistance in insect pests and plant pathogens and a general need for more sustainable pest control strategies. Active and long-term colonization of the root surface of the plant and effective expression of disease-suppressive traits are generally considered prerequisites for successful suppression of horticultural crop diseases by rhizobacteria. The important mechanism of biocontrol by PGPR involve competition and production of antibiotics such as 2,4-diacetylphloroglucinol (DAPG), pyoluteorin (PLT), pyrrolnitrin, phenazine-1-carboxylic acid (PCA), 2^-hydroxy phenazines and phenazine-1-carboxamide (PCN). Siderophores, including pyochelin and pyoverdine which chelate iron and other metals also contribute to disease suppression by conferring a competitive advantage to biocontrol agents for the limited supply of essential trace minerals in natural habitats. Induced systemic resistance (ISR) is a state of increased defensive capacity developed by the plant when appropriately stimulated, through activation of latent resistance mechanisms induced by diverse agents including rhizobacteria. Microplants are first grown in vitro under aseptic conditions devoid of microorganisms. They are then transferred to a post vitrum substrate for acclimatization. By creating a beneficial rhizosphere in microplants at an early stage, the plants could be better protected against biotic and abiotic stress that occurs in the greenhouse or in the field. The beneficial rhizosphere can be created by biotization of microplants with PGPR. The search for PGPR to control postharvest decay of fruit crops has been actively pursued and promising strategies have been practiced nowadays. Biological control of postharvest diseases of perishable horticultural crops with PGPR is complex and involves a number of mechanisms to suppress the development of the disease. PGPR, being a potential candidate in disease management through multiple mode of action, it becomes highly imperative to know its different role in the management of plant pathogens.

Introduction

The common mycorrhizal association in most of the plants is the arbuscular type occurring in the majority of agricultural and horticultural crops. Arbuscular mycorrhizae (AM) are formed by non-septate Zygomycetous fungi belonging to the genera Glomus, Gigaspora, Acaulospora, Sclerocystis, Entrophospora, Scutellospora, Archaeospora and Paraglomus in the order Glomales. These fungi are obligate symbionts and have not been cultured on nutrient media. These endophytes are not host specific although evidence is growing that certain endophytes may form preferential association with certain host plants. Several investigations indicted that even in unsterile soils plants do respond to inoculation with efficient strains of arbuscular mycorrhizae. Numerous experiments have been conducted in different parts of the world confirming this growth improvement. The increased growth of mycorrhizal plants is favoured in soils with low to moderate fertility. More specifically, soils favouring mycorrhizal growth stimulation usually have one or more essential nutrients, especially phosphorus, in limiting concentrations.

The mechanism of improved plant growth caused by mycorrhizal inoculation has been investigated by many workers. Greater soil exploration by mycorrhizal roots as means of increasing phosphate uptake is well established. They also improved the uptake other diffusion-limited elements like Zn, Cu, etc. The other beneficial effects are their role in the biological control of root pathogens, biological nitrogen fixation, hormone production and greater ability to withstand water stress (Bagyaraj, 1984).

Introduction

Increasing production of cereal crops, oil seed crops, and horticultural crops is becoming more important than ever before owing to increasing population and changing food habits of the people. The modern tools of biotechnology are being exploited to the fullest throughout the world for developing transgenic crop plants with improved traits. Already about 20 countries in the world are growing transgenic crops, predominately with traits such herbicide tolerance and resistance to insect-pests. However, there is a constant fear of pollen flow from theses transgenics to the neighbouring non-transgenic fields or to their weedy or wild relatives. It has become a matter of great concern to all biotechnologists to develop alternative strategies to prevent the pollen flow.

The best alternative strategy available today to circumvent the nuclear- transformation associated bottlenecks in developing tenable crop transgenics is the chloroplast transformation technology. This technology allows introduction and insertion of foreign genes into the chloroplast genome, called plastome. Chloroplasts are the site for photosynthesis in plants mostly present in leaves. In general called plastids, they are also present in other parts of the plant. For example, chromoplasts in coloured leaves and fruits, amyloplasts in starch storing organs, leucoplats in roots, and etioplasts in dark-grown seedlings. The plastids arise from proplastids - the undifferentiated form of plastids present in most plant cells. Just like nucleus, these plastids (and also mitochondria) contain their own genetic material on the chloroplast genome.

ABSTRACT

Of the total production of the crop yield, only 63 per cent is available for human consumption. The remaining is lost in more or less equal proportions to weeds, pests and diseases. Prior to genetic engineering, the exchange of DNA material was possible only between individual organisms of the same species. In the field of agriculture for instance, farmers have continuously modified naturally occurring species through seed selection and controlled breeding. With the advent of the recombinant DNA technology, it has however been possible to identify specific genes associated with desirable traits in one organism and transfer those genes within and beyond the boundaries of species into other organisms.

1. Genes for herbicide resistance

Modern agriculture has developed a range of effective herbicides to tackle the effects of weeds on crop yield. Some of the most useful of these are broad-spectrum herbicides because they are active against a wide range of weeds. However, these can only be used at times when the crop is not itself vulnerable to herbicide action. The development of herbicide-resistant crops therefore offers the opportunity to spray crops at the most effective time to kill weed species without damaging the crop plants. By definition, herbicides are much more toxic to plants than to animals. Therefore, it is not surprising that they generally affect ‘plant-specific’ biological processes. The herbicidal activity of many herbicides has been found to result from the specific inhibition of a single enzyme/protein. The following are four distinct strategies for engineering herbicide resistance: i. Overexpression of the target protein, ii. Mutation of the target protein, iii. Detoxification of the herbicide, using a single gene from a foreign source and iv. Enhanced plant detoxification.

ABSTRACT

The coastal ecosystem happens to be one of the most productive ecosystems. This ecosystem has been under different kinds of threats such as climate change and consequent rise in sea level, increase in population and depletion of natural resources. All this has given rise to an increase in the level of abiotic stresses such as salinity, alkalinity, and drought affecting the agricultural productivity in the coastal region. Salinization is posing an increasing problem in coastal and agricultural areas reducing plant productivity and yield. Salinity is one of the major abiotic stresses decreasing the plant productivity.

Salinity is a significant factor limiting agricultural productivity and affecting about 9x 10⁸ hectares worldwide. Poor quality of water for irrigation and current unsustainable irrigation practices has significantly resulted in salinization and other forms of soil damage. About one third of all irrigated land is affected by salt due to secondary salinization. It is estimated that 50% of all arable land will be salinized by the year 2050. The problem of secondary salinization is also becoming more serious as it represents loss of highly productive lands. Added to this is the problem of coastal salinity where intrusion of seawater into arable land due to erosion of coastal habitat has rendered it unsuitable for cultivation. Salt-affected soils (~11 million ha in South and Southeast Asia) are found along coastlines or in inland areas where evaporation is greater than precipitation.

ABSTRACT

The process of developing new crop varieties involves many steps and takes several years. In recent times, biotechnological advances have helped in reducing these considerably. Apart from the techniques of haploid culture and genetic engineering, one of the tools which is making it easier for scientists to select plant traits and develop new varieties is the use of molecular markers. Molecular markers can be used for (a) characterization of germplasm (b) varietal identification and clonal fidelity testing (c) assessment of genetic diversity (d) validation of genetic relationships and (e) marker- assisted selection. These have widespread applications in management of genetic resources as well as in breeding programmes. Marker-assisted selection has practically revolutionized breeding programmes. Traditionally, plant breeders have selected plants based on their visible or measurable traits called the phenotype. But this process can be difficult especially in the case of multigenic or quantitative traits. Molecular markers can be used to trace linkages with traits of importance. In the area of horticulture, this is a very useful tool in tree breeding, where the breeder has to wait for several years for phenotypic expression of the desired trait. A number of DNA marker technologies are now available and rapid advances are being made in the development of more sensitive marker technologies. The techniques involved, the various applications of DNA marker technologies in horticultural crops and future perspectives in the national context have been discussed.

ABSTRACT

Genetic improvement of crop plants through conventional plant breeding has made tremendous contributions to the breakthrough in the global agricultural production. Recently, an array tools and techniques in the field of molecular biology has become available for supplementing the conventional genetic approaches. Consequently, new integrated approaches are being designed. One of the approaches employs molecular markers for genome mapping, gene tagging and marker assisted selection (MAS). With the complete sequencing of whole plant-genomes and a large number of random cDNAs in many different crop species, newer opportunities are emerging. This presentation is an attempt to briefly describe the current applications of molecular markers and to highlight their future prospects.

Molecular markers

Molecular markers are heritable differences in nucleotide sequences of DNA at corresponding position on homologous chromosomes of two different individuals, which follow a simple Mendelian pattern of inheritance. These differences are detected employing two basic techniques: (a) Southern blot hybridization and (b) Polymerase chain reaction (PCR). Restriction Fragment Length Polymorphism (RFLP) is the first molecular marker system to be conceived and developed. It is based on the southern blot technique. Markers such as random amplified polymorphic DNA (RAPD), sequence tagged site (STS) and amplified fragment length polymorphism (AFLP) are generated by enzymatic amplification of DNA by extension of oligo nucleotide primers and therefore, are based on PCR. Single/simple nucleotide polymorphism (SNP) markers are based on DNA sequence differences as revealed by sequencing and assayed by various techniques.

ABSTRACT

Activity patterns of Grey Jungle fowl, Gallus sonneratii were studied at Gudalur Range (9º 37’ N, 77º 16’ E) which is 23² km area in Theni Forest Division, Western Ghats, Tamilnadu from January to December 2005.

ABSTRACT

In social Hymenoptera, the females carry out nest building, brood care and foraging, while males generally do not take part in any of these social behaviours and act solely as reproductives. The interesting phenomena of cooperation and altruism

Botany :The cabbage plant, Brassica oleracea, is an herbaceous annual or biennial vegetable in the family Cruciferae grown for its edible head. The head of the cabbage is round and forms on a short thick stem. The leaves are thick and alternating with wavy or lobed edges and the roots are are fibrous and shallow. The plant produces large yellow flowers. The densely leaved heads can range in size from 0.5 to 3.6 kg (1-8 lb) depending on variety. The plant is usually grown as an annual.

ABSTRACT

Queens of 4 post-emergence colonies of primitively eusocial wasp, Ropalidia marginata were observed for their propensity to acquire and handle foraged material on naturally occurring free foraging nest. The queens were inclined to acquire pulp loads than food loads. 

ABSTRACT

The coconut eriophyid mite, Aceria guerreronis Keifer is a serious pest of coconut in Kerala, Tamil Nadu, Karnataka, Andhra Pradesh, Orissa, West Bengal, Maharashtra and Gujarat. The mites reside underneath the perianth of nuts and feed on the soft meristematic tissues of the young nuts. Their feeding damage is evident as scars on the surface of the older nuts. The damage results in reduction in size of nut and increases labour for dehusking the nuts.

ABSTRACT

Folivorous bats consume flowers and fruits, effecting seed dispersal and pollination. Adaptation of plants according to the type of pollinator is called pollination syndrome. Some of the adaptations of bat-pollinated syndromes are nocturnal anthesis

ABSTRACT

The Indian short-nosed fruit bat, Cynopterus sphinx is one among the three paleotropical species known to make tents. Once a tent is made, male typically defends it against other competing males and also defends the females who join his tent.

ABSTRACT

Benthic fishes represent a significant component of riffle communities. Our 10 year study on two benthic fishes, Crossostoma lacustre and Rhinogobius candidianus which are sympatric in Hapen Creek, Northern Taiwan, reveals that these species exhibited mesohabitat overlaps but were segregated at the microhabitat levels. Both species preferred riffles and avoided rocks. Heavy flow (typhoons) had an inhibitory effect on the fish densities. The fishes may not be able to swim against the strong currents and might get carried away downstream. The recovery time (number of days after a peak, when the densities were restored to normalcy) for C. lacustre was = 13 days and for R. candidianus, it was = 16 days. Recovery was faster at the downstream (~13-15 days) as opposed to upstream (~1416 days). Direct estimation of the linkage between the hydrological or geomorphological variables and the well being of fish populations is one of the first steps in formulating an efficient, effective conservation plan or restoration strategy to preserve these species for the future.

ABSTRACT

Tropical wet evergreen and tropical moist deciduous forests were the preferred habitats of the Brown-hawk Owl. Detection rate and response to the broadcasted calls were highest during the breeding season and in all the census points, more than one individual i.e. either in pair or three individuals were detected. Besides conspecific species, some heterospecific species were also found to respond to the broadcasted calls of Brown-hawk Owl, where the Brown-hawk Owl was not detected during the Initial Quite Listening survey. Moreover, approach of the sympatric species was observed only in the riparian strip and in rest of the habitats they responded only with calls. No significant seasonal difference was observed in the habitat utilization but seasonality was observed in the response and the approaching distance to the conspecific calls broadcasted. Additionally, the response to the conspecfic calls indicated that the owls were responding to the conspecfic calls throughout the year.

INTRODUCTION

Molecular tools generally refer to molecular genetic tools. Although the first use of these tools began more than four decades ago, whenLewontin & Hubby (1966) used allozymes to find out the amount of genetic variation present in wild populations of Drosophila, the lack of expertise and high cost of these tools have prevented their widespread use among ecologists in general and behavioural ecologists in particular. But recently the accessibility and costs of these techniques have come down a lot and with the right kind of collaboration, lack of expertise is no longer an issue.

As was mentioned above, the Lewontin & Hubby’s (1966) investigation was done using allozymes. Although still an option, user-friendly neutral nucleotide markers are more preferred by investigators nowadays. The discovery of the polymerase chain reaction (PCR) in 1983 by Kary Mullis was the single landmark in this field, if one has to mention one. The use of molecular markers has totally revolutionized the field of ecology. It has provided ecologists the tool to ask questions, which were hitherto impossible to tackle and also to answer questions with much more precision and accuracy than was possible till now. It has toppled long held beliefs, sometimes, romantic ones, by ecologists.

ABSTRACT

The Indian false vampire bat, Megaderma lyra detects and captures prey (e.g. frogs) mainly by listening to the rustling sounds that are created when the prey is on ground. In addition, echolocation and vision are also involved. Mothers of M. lyra take meticulous care of their young. At the age of about seven weeks, juveniles exhibit gleaning flights. Among eight mother-young pairs, four young (group A) began to capture frogs at the age of 62 days

ABSTRACT

Insects are considered the most successful in the animal kingdom. Many factors contribute to their success. One major factor that operates strikingly is the economy and optimal use of energy. One can give several examples taking the life of a single insect

ABSTRACT

Ethology, the biology of behaviour has been a fascinating area of biological investigations during past few decades. In recent past the information gathered by reputed ethologists on social behaviour of insects, fishes, birds and human beings are very helpful in the application of these principles for the welfare of the humanity as well as for the environmental sustainability. Ethology differs from the study of Animal Behavior, in that animal behaviorists generally are interested in learned behaviors while ethologists concentrate on innate behaviors.

ABSTRACT

Male crickets use acoustic signals for long-distance mate attraction. Each cricket species has a unique calling song, used by females to recognize and localize conspecific males. Field cricket songs have wavelengths of several centimeters, which pose a difficult problem for these small animals in terms of localizing males, particularly in choruses. The chorus structure in terms of spacing, call intensity and timing, are important determinants both of the ability of males to synchronise their calls and of female mate-finding strategies.

ABSTRACT

Social primates appear to be knowledgeable about one another’s behaviour to different extents. But do they know as much about one another’s beliefs and intentions? Are they adept at recognizing the similarities and differences between their own and others’ states of mind?

ABSTRACT

Science essentially involves confronting our ‘models’ of nature, against data from the real world, in a continuous effort to refine our knowledge of the system under study. Scientific monitoring of animal populations is therefore best viewed in the context of questions such as why monitor, what to monitor and how to monitor.

ABSTRACT

Malabar Spiny Dormouse (Platacanthomys lasiurus), the endemic rodent found in the Western Ghats of South India was studied in the Peppara Wildlife Sanctuary, Thiruvananthapuram District, Kerala, to determine the status, distribution, food and feeding of the species.

ABSTRACT

Insect societies such as those of ants, bees, wasps and termites are characterized by reproductive division of labour and cooperative brood care. Thus these societies consist of one or a smallnumber of reproductives (usually only queens but also kings in the case of termites) and a large number of sterile or nearly sterile workers

ABSTRACT

Studies on the behaviour of animals are of utmost importance in the conservation of species. Ecology of the communities and individual species has to be examined in terms of different activities to understand the requirements of the species. Foraging and breeding are the major activities while resting and flight maintenance are also essential, although the time spent might vary in different species or situations.

Bird community studies conducted along with my students in different habitats in the Western Ghats since 1995 showed how the species are associated with each other and the impact of habitat changes on them. Endemic and threatened birds of the Western Ghats were specific about selection of habitat and food in different seasons. Identification of such critical habitats is crucial for conservation and management.

The studies on the bird community and drongos at Thekkady, Periyar Tiger Reserve conducted by me during 1979 to 1982, examined the association of drongos with other species in the area, especially while foraging. They fed mostly in mixed foraging flocks which is beneficial to all the participants. The strategy adopted by them for ecological isolation to reduce competition was by selecting different strata and substrate of the vegetation, varying sizes of insects, and methods of feeding.

In the case of wetland birds also habitat selection is a major behaviour limiting their numbers. For the threatened birds such as the Siberian Crane and the Andaman Teal, habitat quality and food availability were critical. Habitat degradation with over abundance of grass and reduction in sedges resulted in spending long duration for feeding and less returns.

Breeding behaviour of birds is interesting because of their strategies such as when to nest and where to nest. Studies on the seasonality have shown the importance of climatic factors. Many of our land birds nest during summer. Nest-site is also crucial as selection of the site with suitable macro and micro-habitats determine the success of the brood. The habitat patches for the individual pairs or groups of breeding birds which are defended against intruders are termed as territories which play a vital role in the distribution and density of birds. Thus the strategies adopted by species are dependent on the environment and species specific constraints affecting the survival of the species.

ABSTRACT

Education begins at home, then in community and finally in the educational institutes. At present 90% of the children in the age group of 6-14 years are receiving free primary education. Education policy of the 11^th plan states that there should be free and compulsory secondary education for all. To meet this goal, additional schools have to be set up to cater to the 30 million students. To teach the 30 million students atleast one million teachers would have to be trained to ensure the 1:30 teacher– student ratio. How do we plan to meet this target?

The projected target has to be met by developing innovative teaching methods in the institutes of higher learning. These methods have to be technology based, as well as community based regional approach. Emphasis has to be given to Liberal Education where there has to be a close interaction between the teacher and learner. The Open and Distance Learning isone such System which can be compared to Liberal Education– where there is flexibility in time and pace of learning for the learners. Reforms and innovations have to be brought in this system of education with utmost caution so that there is no compromise on quality and ethics, since every age has its own ethical environment.

Ethics in this context means traditions and culture of the small communities. This is more so in the North Eastern Region where there is an intimate connection between large and small communities. This region is rich in its community based values, bioresources and cultures. Need based Vocational and Professional courses have to be designed for enriching the region with human resources infused with sophisticated skills, resulting in the economic growth for the region. This method is envisaged to take care of the social challenges, traditions and cultural ethos.

Distance Education coupled with Information Communication Technology plays a pivotal role in meeting the requirements of today’s knowledge society by cutting across the barriers of time and geographic isolation.

ABSTRACT

Bats: A colony of 500 insectivorous bats of Hipposideros speoris inhabited a natural cave in Madurai (9^O58’ N. lat; 78^O10’ E long). At a depth of 40 m, the cave experiences a constant temperature of 27 + 0.1^OC, 95 % relative humidity and absolute and perpetual darkness. Therefore there were no day/night cues. Yet all the members of the bat colony flew out 10 to 15 min. after sunset as though they knew the time of sunset. Recorded flight and rest experiments in flight activity cages and a hand-wound Thermohygrograph drum 40 m from the cave mouth over periods of 50 days revealed that the free-flying conspecific bats were socially synchronizing the activity patterns of the three captive bats. Bats were telling other bats time.

Mice : In the field mouse, Mus booduga the mother conveys information of day and night to her pups by means of her presence and absence (PA) cycles. Her presence meant day and absence denoted night. We named this phenomenon maternal entrainment. Such entrainment of the time sense of the pups was possible if in every cycle the mother was presented for a minimum of 8 hr but not exceeding 16 hr. Therefore 8 hr and 16 hr describe the limits of maternal entrainment.

Botany

The plant is highly cross pollinated due to heteromorphism and bees being the major pollinators.

Varieties: PKM 1 & PKM 2

Method of seed production : Seed to Seed.

Land requirement : Uproot all the wild and non specific moringa trees if any near the field within a radius of 1500ft. Good drainage facility is must for moringa.

Isolation requirement : A distance of at least 500 M is necessary for seed production.

Season : Early season (July August), Mid season (September), Late season (October -November). Best season is September October, so that flowering starts during summer which facilities better pollination and seed set.

Abstract

The landslides of the hill ecosystems are either due to the natural morphotectonic and morphodynamics processes of the planet earth or due to the anthropogenic effects or due to the combinations of the both. In the Indian subcontinent, the landslides are reported from three major provinces viz: Himalayas, Westernghats and The Nilgiris. While the landslides of the Himalayas are demonstrated to be predominantly due to active tectonics, the landslides of the Westernghats are attributed to excessive weathering and rock fall. On the contrary the landslides of the Nilgiris have been thought to be due to extensive deforestation and the related increase in the pore pressure during rainy seasons. But the studies carried out in the recent years show that not only in the Nilgiris but also in other hill systems of Tamil Nadu, the landslides seem to be related to the recent earth movements. This is very significant in the context of fastly recurring seismicities in South India and hence this aspect warrants detailed studies for landslide mitigation.

Abstract

The analysis of IRS - 1A satellite imagery has indicated the existence of two NE - SW trending sub parallel faults along which the coast is undergoing land subsidence as revealed by the concavity in the shore line, preferential migration of the river systems and the drainage congestion, absence of beach ridges, occurrence of off shore shoal etc. The study has further indicated chains of tectonically induced environmental problems such as ground water logging, coastal zone flooding, storm surges, harbour sedimentation etc.

INTRODUCTION

Coastal zones are always dynamic and active, because of the multivariate morpho tectonic and morpho dynamic processes, viz: tectonic, fluvial, marine and aeolian which act in varying degrees and duration along the coasts. As these geomorphic / morpho dynamic processes act in varying permutations and combinations in different segments of the coasts, the land - ocean interactive phenomenon vary greatly in time and space, which in turn frequently and dynamically alter the coastal environment, and cause fragility to the coastal ecosystems. Further, as the coastal zones act as the junction between the Continents and the oceans, even mild earth movements exhibit exemplified expressions in land - water distribution pattern along the coasts. The green house effect and the much apprehended sea level rise and the disasters like cyclones also contribute in their own way in accelerating such land - water distribution / land - ocean interactive phenomenon.

OBSERVATION

The examination of the IRS - 1A imagery under raw and the digitally enhanced modes vividly display heavy concentration of suspended sediments in certain sectors along the east coast of Tamil Nadu. Such pockets of suspended sediments are seen as long and linear bodies trending parallel to the coast to the strike length of 20 - 30 km and width of 5 - 10 km. Such Phenomenon of suspended sediments concentration are strikingly observed in two sectors. One in between Tuticorin harbour and Vaippar river mouth and the other just at the mouth of Ponnaiyar river along Cuddalore-Pondicherry coast. Both of them are observed along conspicuous (Fig.1& 2) concave coasts.

The resources on the land have started showing sign of faster depletion owing to the population explosion, over exploitation of mineral and water resources and also the improper exploitation and the related wasting of the natural resources. Hence a time has come to search for more and more newer natural resources amongst which the ocean resources gain supreme importance as this treasure is yet to be hunted due to the non - availability of suitable technology for the same.

Such ocean resources mainly include the mineralogical and biological resources. The ocean biological resources, their birth, growth, population and migration greatly depend as chlorophyll content, total dissolved oxygen, total suspended solids, salinity etc. These parameters which constitute the marine environment drastically change in a quick span of time owing to the dynamically changing marine forces.

Abstract

The present study has revealed that the NE-SW and WNW-ESE trending sinistral faults are very active along the Tamil Nadu coast and the same have caused considerable slope modifications along the Coleroon and Karungalar rivers which are well-manifested in the land, water and mudflat distribution pattern. Similarly, the progradation of the land in Vedaranniam nose is due to the rise of Pattukottai-Mannargudi area and the time transgressive modifications of the Vedaranniam backwater indicates the opening up of the N-S trending Pleistocene-Holocene faults.

Abstract

The art of remote sensing has opened up many vistas in the study of river migration as satellite photographs, both in their normal and digitally enhanced modes, vividly show the rivers and their migratory signatures. The rivers migrate for various reasons amongst which tectonic movement is one of the main causes. In the present study an attempt has been made to exhibit the palaeochannel network of the rivers of Western India and integrate them with lineament fabric, so as to understand the Quaternary tectonics of the region. The study has shown that Western India shows considerable signs of Quaternary tectonics.

The great Indian epic ‘Ramayana’ says that ‘Lord Rama’ has tried to cross over the Bay of Bengal so as to reach Sri Lanka from India from three points along the southeastern fringe of the Indian coast. Firstly, he is said to have tried to cross from Vedaranniyam which is mythologically called as ‘Kodiyakkarai’ Secondly from Manamelkudi and finally crossed over to Sri Lanka from Rameswaram Island (Fig.1), as the former two coastal locations were widely separated from Sri Lanka by Bay of Bengal and the Rameswaram Island was nearer to Sri Lanka during that period. But, the recently acquired satellite data shows the huge accretion of sediments and rapid land building activity off Vedaranniyam coast (Fig. 2 and 3). The geomorphic interpretations carried out using IRS 1A imagery and 14^C archaeological dating of such geomorphic features have shown that such ongoing sediment accretion phenomena off vedaranniyam nose might in future connect the Vedaranniyam part of Indian Peninsula with Jaffna Peninsula of Sri Lanka if the sediment accumulation continues unabated. The sediment accretion in this area, therefore, requires detailed studies particularly in the context of the coastal ecosystem (Fig. 1).

Abstract

The Remote Sensing and the followed up field based investigations show that the Tamil Nadu coast, India, is facing series of geoenvironmental problems due to tectonic movements and morphodynamic processes. Such problems pose a challenge to the engineering geologists. The paper discusses such challenging engineering geological problems and plausible remedial measures.

Abstract

The tectonic and the geomorphic features observed along the west coast of the area between Mangalore and Cape Comorin show that the NNW-SSE trending west coast has been carved out by the Western Ghats orogeny and the related NNW-SSE trending release fractures. The sinuosity of the otherwise straight coast line is due to Quaternary cymatogenic arching caused by the thrust related to the northerly movement of the Indian plate. The coast line has further attained peaks, projections and serrations due to the ENE-WSW trending series of Precambrian extension fractures which were reactivated gaining the northeasterly directed forces from the rising Carlsberg ridge. Overall, the west coast is being tectonically evolved even today due to the rise of Carlsberg ridge and the Indian plate movement.

Abstract

There is a consensus amongst the geoscientists that overall there has been progradation along the east and west coasts of peninsular India. However, the present day configuration of the coasts and some of the geomorphologic features such as absence of spit and delta along west coast and absence of major estuaries and petroliferous structures along east coast still remain controversial. The present study, based on the appreciation of certain geomorphological and tectonic features on Landsat imagery and aerial photographs of southern part of Indian Peninsula, suggests that the evolution of the coastline has been mainly controlled by tectonism.

The tapering nature of the coastline is attributed to the Precambrian orographic axis. The serrated nature of the post Precambrian coast line is due to the Precambrian transverse faults, whereas the serrated margin of the post Gondwana, Post cretaceous and post Tertiary coast lines are attributed once again to the Precambrian faults reactivated time and again. During the Quaternary period the coast line has undergone many modifications. The coast line attained sinuosity due to Pleistocene folding which is well manifested by river migration. The coast line was subsequently faulted and shifted with en echelon pattern due to N-S regional compression which is referable to the collision of Indian Plate with Tibetan plate.

Amaranth is an annual herb with erect growth and scarce to profuse branching habit. Flowers are borne terminally and in axils of leaves in clusters. Basic unit of inflorescence is called as glomerule. Flowers are small, unisexual and monoecious. Proportion of male and female flowers varies in an inflorescence. Each glomerule consists of a staminate flower and a number of pistillate flowers. The extent of cross pollination is governed by proportion of male and female flowers in an inflorescence and position of inflorescence in plant

Onion is one of the oldest cultivated plant species. Onion forms the bulb in the first year and the seed in the second year. The leaves arise from a shortened crown stem. The sheaths of the older or outermost leaves enclose the younger ones. The basal portion of the leaves encircles the stem, and thickens to form the bulb. The stem elongates during the second year forming the flower stalk. The onion has a fibrous root system extending to a depth of over one meter, but most of them are found in upper surface about one-half meter area.

Remote sensing has proved its credibility beyond doubt in natural resources survey and environmental monitoring owing to its synoptivity, multispectral photographic capability and repetitive coverage. While its synoptivity gives unbiased information on the regional panorama of the earth surface, its multispectral possibility aids precise interpretation of various objects, as different terrestrial objects exhibit various spectral responses in different bands of the electromagnetic spectrum. Amongst various terrestrial objects, water has a characteristic spectral response of its own, i.e. it permits the blue / red part of EMR (electromagnetic radiation, 0.4-0.8 µm) to penetrate inside. On the contrary, it totally absorbs the infrared part of EMR (0.8-1.5 µm). As such blue/red part of EMR penetrates the water bodies, the impurities and suspended sediments are seen very clearly in various shades of gray as and when the water bodies are shallow. Many workers, therefore, have used blue / red band of the satellite data in such water-quality studies^l-3. Hardy⁴ has observed that the infrared light in the spectral regions of 0.6-1.4 µm has the potential to map the turbidity in the ocean water, whereas Kritakos et al ⁵ have used the rationed data of visible and near infrared bands (0.4-1.1 µm) and obtained better results for water quality monitoring. Keeping such facts in mind, the blue/red band (band 2) of the IRS 1A satellite data was used to configurate the bathymetry along Madras coast in Bay of Bengal (Figure 1 a).

In the present study, the IRS lA band 2 data (0.52-0.59 µm) of March 1991 was used and subjected to edge enhancement studies for the coastal zone of Madras (Figure 1 a). Such edge enhancement normally sharpens the edges of two contrasting objects or sharpens the edges of objects of contrasting relief. In such edge enhanced data, few

Pumpkin (Cucurbita maxima Duch.) is a well known and widely cultivated vegetable variety of the family Cucurbitaceae. The seed production can be done in summer season (February - March) and in rainy season (April - May). In Tamil Nadu, sowing during July – August is best for seed production.

Botany: Bottle gourds belonging to the family cucurbitaceae is an annual vine having white flowers and smooth, large, hard-shelled gourds. Brownish seeds are numerous in a whitish green pulp. Each seed is somewhat rectangular in shape with grooved notches near the attached end. Grown most often in warmer climates, this squash grows from 6 to 36 inches long and 3 to 12 inches in diameter.

Seeds leaves, flowers and young stems are all edible. Helpful in shedding extra calories. It contains higher concentrations of Dietary Fiber, Vitamin A, Vitamin C, Vitamin K, Vitamin B6, Folate, Potassium, Manganese, Protein, Vitamin E, Thiamin, Riboflavin, Pantothenic Acid, Calcium, Iron, Magnesium, Phosphorus and Selenium. A rich source of minerals and vitamins, bottle gourds contains many healing and medicinal properties. The cooked vegetable is not only easy to digest but also contains cooling, calming (or sedative), diuretic properties. It contains low calories also has iron, Vitamin C and B complex. Regular consumption of this vegetable provides relief to people suffering with digestive problems, diabetics and convalescents.

Botany:Snake gourd belonging to the family Cucurbitaceae native to Southeastern Asia and Australia but cultivated throughout the world for its curved and oddly shaped fruits that appear like snakes hanging on the supports or ground. This subtropical plant grows very fast in warm climates and produces lots of fruits for a long time. It is suitable for growing for home garden and fresh market.

Climate and soil: Snake gourd is adapted to wide variety of soil and climatic conditions. It requires a minimum temperature of 18^oC during early growth, but optimal temperatures are in the range of 24–27^oC. Snake gourd tolerates a wide range of soil but prefers a well drained sandy loam soil that is rich in organic matter. The optimum soil pH is 6.0–6.7, but plants tolerate alkaline soils up to pH

Varieties: CO1,CO2, PKM 1, PLR 1 and PLR 2.

Pulses can be grouped into kharif and rabi pulses according to their temperature requirements. In India chick pea, pea, lentil and beans require relatively less temperature and are grown in rabi season, whereas others are confined to kharif season. However, kharif pulses can also be grown in pre-rabi on stored soil moisture or as irrigated crops in rabi and summer seasons.

Pulse crops have long tap root system which extracts soil moisture from deeper layers. Water uptake across the depth of rooting zone is not uniform. In general 40 per cent of the total water uptake occurs from first one fourth of the rooting zone, 30 per cent from the second, 20 per cent from the third and remaining 10 per cent from the last one-fourth region of total rooting depth (Nageshwararao and Writ, 1994). Plants often maintain higher root length densities than required in the surface layers to facilitate rapid uptake of recent rain/irrigation before it evaporates.