eChapters

16.1 INTRODUCTION

The world floriculture business has reached to almost over a $ 40 billion mark. It is continuously going through the rapid transitional changes to have more unique and competitive products of wide choice to the consumers. Netherland is ahead in floriculture trade. Throughout the year, a large number of ornamental commodities are imported in Holland and exported back to the countries for its retail and consumption mostly to the countries in the Gulf, Middle-East Asia and America. According to the statistical estimates worldwide, a large quantity is consumed in US and the other countries. For an example, the US alone consumes 100 lacs of cut flowers a day and approximately 4000 lacs every year, though it ranks only 17^th in per capita cut-flower consumption. The average Swiss spends Rs 4500 a year on flowers, nearly four times than that spent by the average American besides the fact that the consumption of fresh cut flower and foliage plant is on manifold increase every year resulting in the competition worldwide for growing of exportable eco-friendly products. At the same time there is great environmental consciousness towards transforming floriculture with “natural and unspoiled” system of having the exportable produce into a mass and its ease to transport to any distant market. The system relies greatly on the industry with extensive network of breeders, greenhouse managers, field workers, auction houses, sales representatives, shippers, and florists to offer consumers a variety of choices matching their taste. This is the fact that in the recent times, the commercial growers don’t rely on the nature to introduce the genetic mutation that will make them millionaires but depends on the art and scientific knowhow to create a novelty in its own. This has resulted in the seriousness and painstaking effort of the growers to produce the plants in new forms and shape to put forward a new plant with extra-ordinary marketable characteristics every year, e.g. compact chrysanthemum, kalanchoe, bromeliads, orchids, etc (Plate1) are some of the common products with an unusual and eye-catching hue in the European markets. Similarly, the consumers can purchase gerberas with blooms as wide as salad plates and roses with yard-long stems perfectly suited for valentine-day gifts which mainly they get produced under the specific and artificial environment created for a specific growth stages of the plant.

15.1 INTRODUCTION

Vegetables are rich sources of many essential micronutrients, including vitamin C, vitamin K, folate, thiamine, carotenes, minerals, and dietary fibre. In addition, vegetables are rich in health related phytochemicals, such as antioxidants. Such phytochemicals play an important role in reducing the risk of many chronic diseases. Therefore, it is essential to produce more vegetables to feed our ever growing population. In this context, use of genetically improved, disease resistant and high yielding varieties in precision farming may play a significant role in increasing vegetable productivity and production.

15.2 EXPLOITATION OF GENETIC RESOURCES

The genetic resources of a crop may be defined as the sum total of hereditary material, i.e., all the alleles of various genes present in a crop species and its wild relatives. Genetic resources are broadly grouped into two major types (i) cultivated germplasm, and (ii) wild germplasm. Alternatively, they may be termed as (i) indigenous (from the country in question), or (ii) exotic (from another country) based on their place of origin. Genetic resources consist the following five types of materials: (1) land races, (2) obsolete varieties, (3) modern varieties or varieties in cultivation, (4) breeding lines, and (5) wild forms and wild relatives.

14.1 INTRODUCTION

The efforts for harnessing the natural resources for sustainining the human race have been ‘on’ since the beginning of the civilization. The basic needs of food, fuel and fodder are obtained from the land resources with the combination of water and sunlight. The combination of information technology and use of hi-tech equipments paved the way for the introduction of precision horticulture. Precision horticulture may be defined as application of a holistic management strategy that uses information technology to bring data from multiple sources to bear decision associated with agriculture production, marketing, finance and personnel. Enhanced input efficiency is an important component of horticultural production under precision horticulture site specific management. Enhanced input efficiency in crop management can be obtained only when suitable varieties, desired amount of nutrients and water based on calculations, at right time and by proper method are used.

With recent advances in geographic positioning system, remote sensing, data processing, harvesting equipment, fertilizer and pesticide applicators, the approach can be used from a more practical stand point to identify variability and to use the variable rate of inputs over an entire field.

In recent years, there is considerable awareness about the nutritional security and food safety. More emphasis is given to underutilized fruits due to their high nutritive and medicinal value in addition to being resistant/tolerant to many biotic / abiotic stresses. The demand of these fruits are gradually increasing owing to tremendous potential for commercial exploitation aimed at improving the economic status of the poor and marginal farmers. An area, which needs immediate attention, is the collection, documentation, conservation and utilization for their sustained production and popularization.

13.1 INTRODUCTION

The hot arid regions are spread over about 31.7 million ha area mainly in the States of Rajasthan, Gujarat, Andhra Pradesh, Punjab and Haryana, which inhabit on an average 61 persons per square km making up a home for population of nearly 20 million people. The Indian arid zone is characterized by high temperature and low and variable precipitation which limit the scope for high horticultural productivity. However, these conditions greatly favour development of high quality production of fruits such as date palm, ber, pomegranate, citrus, aonla, bael, grapes, guava and vegetables such as cucurbitaceous crops, spices and some medicinal plants. The optimized technologies and inputs could increase the existing low productivity. It is now realized that there is a limited scope for quantum jump in fruit and vegetable production in the traditional production areas. The amelioration of the extreme conditions is also considered vital for life support to the inhabitants of this area. The recent awareness regarding the potential of these ecologically fragile lands for production of quality horticultural produce has not only opened up scope for providing economic sustenance for the people of this region, but also for bringing new areas to increase production through horticulture.

The arid horticultural crops have developed and/or modified to perform certain vital physiological functions even under stress. Strong deep root system (ber, bael, aonla, wood apple, jamun, etc.), moisture synchronous flowering and fruit development (ker, lasora, aonla, pilu, etc.) and other xerophytic characters i.e. leaf shedding in summer (ber), scanty foliage (ker), spiny cladode (cactus pear), mucilaginous sap in plant part (ker, gonda, pilu, bael, etc.), sunken stomata and fur/ hairiness and waxy coating on the leaf surface (phalsa, ber, gonda, fig, etc.) thorny nature, and selective or reduced absorption of cation (Na⁺) and anions (Cl^-, SO4^—) for survival under adverse arid conditions are peculiar adaptations. Therefore, cultivation of suitable species of fruit and vegetables in the arid areas will increase the sustenance of the inhabitants and provide the alternate sources of income through development of nurseries, small scale industries and exports.

12.1 INTRODUCTION

Oil Palm (Elaeis guineensis Jacq.) is a heavy feeder and needs a balanced and adequate supply of nutrients for growth and yield. Fertilizer is one of the most costly inputs, which accounts for greater part of production costs in the cultivation of oil palm. Large amount of nutrients are removed by the fruit bunches harvested from the mature palms. It is estimated that 25 tonnes fresh fruit bunches per hectare per year removes 93.5 Kg Nitrogen, 11.0 Kg Phosphorous, 92.7 Kg Potassium, 19.3 Kg Magnesium and 20.3 Kg Calcium.

Economic yields of oil palm are achieved when the supply of nutrients from the soil, palm residues and fertilizers are properly integrated in required quantities. Leaf analysis is an analytical tool for detecting the nutrient requirements in oil palm and other perennial crops, which are slow growing and can provide easily, defined standard leaf material for analysis due to leaf phyllotaxis. Nutrient deficiency symptoms are also an important means for determining the nutritional problems in oil palm, since the crop presents easily identifiable N, K and Mg deficiency symptoms. However, by the time symptoms are evident, nutrient deficiency might have already affected growth and yield.

Also the nutrient supply may be insufficient before the appearance of leaf symptoms. So there is a need for a thorough inspection of the leaf canopy to corroborate the results of leaf analysis and identify the areas with severe nutrient deficiencies. The research on oil palm nutrition was carried out under rainfed conditions at Palode, Kerala and irrigated conditions at Pedavegi, Andhra Pradesh.

In India, a great variety of soils ranging from red sandy loams/sandy clay loams (Alfisols), alluvial silt loams (Inceptisols / Entisols), heavy black soils (Vertisols) and acidic red laterite soils (Oxisols) are put to oil palm cultivation. In Andhra Pradesh, it is grown in red sandy, red loamy, red loam with clay base, deltaic alluvium pH - 6.5 to 9.0. In Karnataka, it is grown in red and brown sandy loams and black clayey soils, with pH - 6.5 to 9.0. Red soils, red loamy soils and clay loam soils are used for growing oil palm in Tamil Nadu. Laterite soils are used for oil palm cultivation in Kerala.

11.1 INTRODUCTION

Citrus as a perennial crop occupies globally a place of prime importance amongst major fruit crops including India. The cultivation of citrus in India is dominated by three major cultivars viz., mandarin, sweet orange, limes and lemons occupying collectively an area of 9.23 lakh ha with a production of 86.08 lakh tonnes and productivity of 9.3 tonnes/ha. Nagpur mandarin in India is grown in 0.97 lakh ha area with total production of 8.81 lakh tonnes and productivity of 9.l tonnes/ha, respectively. The productivity of mandarins within the country is highly variable in space and time, the major constraint is inadequate and unbalanced fertilizer use. The commercial cultivation of Nagpur mandarin is extensively confined along the Satpuda foothills of central India comprising Chindwara region of Madhya Pradesh and Vidarbha region of Maharashtra. The nutrient demand is highly variable in space (due to heterogenous soils) and time (due to varying weather conditions). Therefore, determination of crop nutrient requirement is a subject of great complexity. Experiments have shown that soils initially rich in fertility developed a variety of nutrient constraints following the non-synchronisation in demand and supply of nutrients with the orchard age (Srivastava et al., 1998). For example when exchangeable K is not rapidly replenished, crops start drawing on the non-exchangeable K, resulting in soil mining and depletion in soil K reserve. A nutrient level sufficient for one particular productivity level may not hold sufficient for other higher productivity levels. An extensive survey of 18,000 ha area of Nagpur mandarin orchards of central India showed large scale deficiency of three nutrients viz., N, P and Zn, with most of the sites expressing multiple nutrient deficiencies (Srivastava and Singh 2002; 2005). Reduced longevity of commercial citrus orchards due to varying nutritional constraints is one of the major production related constraints highly responsible for poor orchard efficiency (Srivastava and Singh, 2008a; 2008b).

10.1 INTRODUCTION

Agriculture is a very important sector for the sustained growth of the Indian economy. About 70 per cent of the rural households and 8 per cent of urban households are still dependent on agriculture for their livelihood. Though, industrialization of the Indian economy has adversely affected the share of agriculture in the GDP, the fact can not be ignored that India has undergone a series of successful agricultural revolutions-starting with the ‘green’ revolution in wheat and rice in the 1960’s and 1970’s, the ‘white’ revolution in milk to the ‘yellow’ revolution in oilseeds in 1980’s. As a result, India has achieved self-sufficiency in agriculture. Applications of agricultural inputs at uniform rates across the field without due regard to in-field variations in soil fertility and crop conditions does not yield desirable results in terms of crop yield. The management of in-field variability in soil fertility and crop conditions for improving the crop production and minimizing the environmental impact is the crux of precision farming. Geographically, India is widely distributed into several agro-climatic zones, and the information needs for the farming systems in these areas are entirely different. Integrating the application of available technologies to realize farmers’ goals requires a systems approach to farming.

9.1 INTRODUCTION

India is the second largest producer of fruit crops with annual production of 68.4 million metric tonnes from an area of 6.1million ha (Anon 2010). The national horticulture mission commenced in 2005 had fixed a target to double the horticultural production by 2011-12. According to the available production data of horticultural crops, it seems that we are very close to achieve our target. But, if the loss caused by biotic and abiotic stresses is accounted, a sound conclusion can be drawn that still there is a huge scope for productivity improvement in fruit crops.

Among biotic factors bacteria, fungi, nematodes, viruses and insect pests, diseases and other pests are widely recognized as the biggest threat to the sustainable production of fruit crops. Every fruit crop is infected with one or other pathogen/pest, which causes a significant reduction in yield. The disease alone both in field and storage accounts for 25-30 per cent losses (Rangaswami and Mahadevan 2002). Along with diseases, insect-pests also cause reduction in the yield. About 600 insect and mite pests have been reported in temperate fruits alone in India (Sharma and Singh 2006).

Beside biotic factors, abiotic factors (salt, drought, low and high temperature) also limit the potential yield of fruit crops. It is estimated that nearly 10 million ha is affected by salinity/alkalinity in India (Singh 2006). Moreover, fruit cultivars are also to be modified for yield and traits of consumers preference e.g. seedlessness in grapes and citrus.

Genetic improvement can be achieved by following the conventional breeding approaches, when the gene of interest is present in related cultivars/species and the crop is sexually crossable. But due to long juvenility and genetically prevalent problems like incompatibility, sterility in most of the fruit crops and apomixis in citrus, mango and apple, conventional techniques seem to have limited role in the improvement of fruit crops.

Various biotechnological approaches either alone or in combination with conventional breeding approaches can provide a direct solution for the genetic improvement of fruit crops.

8.1 INTRODUCTION

In developing countries like India, sustainable development of horticulture is a biggest challenge. There is need to formulate strategies for their management through “state of art” technologies for harnessing the naturally available resources in a sustainable manner to meet the ever growing demands of fruits. Canopy architecture has its role in influencing the productivity of fruits. It has been well highlighted by Halle and Olderman, (1970) and Halle et al. (1978). The emerging concerns in the area of canopy architecture and its management are the existence of large number of old senile orchards among the fruits crops and the development of a rejuvenation technology to restructure their canopy and enhance productive and remunerative plant life. Actually, canopy management “designing the plant as per need, using inherent plant characteristics in accordance with given set of conditions and resources to make the plant to perform maximum. As a result of canopy management, the trees acquire their natural shape which very often is not ideal for quality production. A majority of the trees attain tall, upright and curved growth structure and the canopy is marked with criss-cross branches leading to a highly dense vegetative mass with very poor penetration of active solar radiation. Such conditions not only affect the photosynthetic rate but also facilitate proliferation of pests as they prefer shady conditions. Consequently with pressure of pest abundance and poor photosynthetic efficiency over the years in want of due care of tree canopy architecture, the trees turn senile and unproductive and uneconomical.

Existence of such unproductive senile orchards has a telling impact on the socioeconomic as well as livelihood status of the farmers and consumers are equally affected with low poor production and poor quality of produce is the biggest problem with old orchard. Uprooting such orchards and undertaking new plantation may not be a wise option considering the long gestation period of orchard establishment and resulting impact on livelihood of farm families, environment health as well as the investment cost. Mass scale uprooting of trees for replacement of the orchard will also have very adverse impact on production scenario at the regional and national level.

7.1 INTRODUCTION

Production of temperate-zone fruits in subtropics may seem fanciful to be initiated, but it is a practice that has existed in localized regions for generations. Seedling peaches are grown in Venezuela, Northern Thailand, and Southern Mexico. No one knows precisely when these species were introduced, but local selection has produced cultivars adapted to areas with little or no chilling temperatures. Rest either does not occur or is sufficiently shallow to be broken by stress induced by defoliation or drought. Commercial cultivations of temperate-zone fruits are well-established in subtropical areas, where winter temperatures allow partial breaking of the rest period. In areas of Northern Mexico, Southern Africa, and Israel, for example, chemical treatments are regularly applied to supplement the effects of limited chilling. Because temperature declines with increasing elevations, many microclimates exist in the subtropics where temperate-zone fruits are not currently grown, but could be. Subtropical regions where temperate fruits are grown include the southern past of California (Mediterranean type), the low deserts of the Southwest USA (hot arid type), the Gulf Coast and most of Florida (humid type), the Southern Mediterranean and Northern Sahara, Northern India, Southeast China, the middle part of South America, and much of Australia. Similar potential climatic conditions are also available in subtropics of India.

6.1 INTRODUCTION

Presently, pressure on productive land is greater than ever before and will be further more in years ahead. Per capita arable land is projected to decline from about 0.23 ha in 2000 to about 0.15 ha by 2050 (Lal, 1991). The global demand for food is projected to increase by 1.5 to 2 times due to ever increasing population and also due to demand for richer diets. On the other hand, volatility in the cost of agricultural inputs and the income generated from farm products leads to instability in the farm economy. Moreover, in conventional system, agriculture is practised for uniform application of fertilizer, herbicide, insecticides, fungicides, and irrigation, without considering spatial variability. In some cases, there is excessive use of nitrogenous fertilizer and pesticides, owing to air and water pollution but there are certain cases, where farmers hardly use any chemicals. Hence, to alleviate the ill effects of over and under usage of inputs, the scenario calls for the introduction of modern technologies to improve crop yield, provide information to enable better in-field management decisions, reduce chemical and fertilizer costs through efficient application, permit more accurate farm records, increase profit margin and reduce pollution.

Precision agriculture is a production system that promotes variable management practices within a field, according to site conditions. This system is based on new tools and sources of information provided by modern technologies. These include the global positioning system (GPS), geographic information systems (GIS), yield monitoring devices, soil, plant and pest sensors, remote sensing, and variable-rate technologies for applicators of inputs. Precision farming is concerned with the management of variability in the dimensions of both space and time. Aspects of precision farming, therefore, encompass a broad array of topics, including variability of soil resource base, weather, plant types, crop diversity, machinery performance and most of the physical, chemical and biological inputs used in production of a crop. These are closely linked to the socio-economic aspects of production system. Success in precision framing is directly related to how well it can be applied to manage the space-time continuum in production system. Thus precision farming is technology enabled, information based, and decision focused. It is the integration of these technologies that has enabled farmers and their service providers to do things not previously possible, at level of detail never before obtainable, and, when done correctly, at level of quality never achieved before. In our country, vast data on various aspects like soil characteristics, climatic parameters, topographic features, crop requirement in terms of consumptive use and nutritional requirements have been generated and instruments needed for recording these parameters are also available. However, applications of precision farming as a package in the farmer’s field have received little attention, although some aspects of precision farming have been prasticed. This has been primarily due to lack of awareness about the potential for increasing productivity and improving the quality of produce with minimum use of inputs.

5.1 INTRODUCTION

Drought and rampant poverty, the double plague of arid region, present a scenario of misery and insecurity across the region where agriculture is the main livelihood and chief source for subsistence of the rural people. The conditions of low and erratic rainfall, extreme temperature conditions, high evapo-transpiration, scarce water resources, infertile and saline soils with ill-defined profile development threaten sustainable agriculture. Sustainable productivity is difficult to achieve by monoculture of either seasonal or forage crops. Thus cropping system approach for agricultural production is of far greater significance in these regions. Traditionally efforts have been made by the native people, obviously to achieve sustainable production ensuring ecological stability, to grow several species together, e.g. pearl millet, moth bean, cluster bean and gram between the natural stands of khejri (Prosopis cineraria), bordi (Zizyphus rotundifolia), lasoda (Cordia myxa), pilu (Salvadora oleoides), and ker (Capparis decidua). The perennial species also provide fodder for sheep and goats during scarcity periods.

Fruit based cropping system is now considered to be the most ideal strategy to provide food, nutrition and income security to the people (Chundawat, 1993, Chadha, 2002, Awasthi and Pareek, 2008). Integration of annual crops with fruit trees yields multiple outputs that ensure production and income generation (Randhawa, 1990 and Osman, 2003) in a sustainable manner. Natural resources (land, solar radiation, water, soil etc.) as well as socio-economic inputs (labour, credit, power, and market infrastructure) are efficiently utilized. Crop productivity under tree canopy is enhanced due to improved soil fertility (Young, 1989) and ameliorative influence of shade by reducing understorey temperature and evapotranspiration (Bunderson et al., 1990). Incorporation of fruit trees into the cropping system is more remunerative. It increases the resilience of the system over time. It enables to i) maximize system productivity on annual basis, ii) utilize resources with high efficiency through due consideration of various interactions and direct, residual and cumulative effects occurring in soil-plant-atmosphere continuum, iii) intensify input use vis-à-vis quality of environment, and iv) impart sustainability of farm resources and environment in long term perspective. The type of horticulture based cropping system in arid region has been discussed in this paper considering these issues.

4.1 INTRODUCTION

Ever since the man appeared on the earth, he has been harnessing the natural resources to meet his basic requirements. Reference to soil, water and air as basic resources, their management and means to keep them pure are mentioned in the Vedas, Upanishads and in ancient Hindu literature. Agriculture began sometime during 10000 BC and during 1930 AD use of chemical came into vogue (Sarswat et al., 2003). The phenomenal increase in population of both man and animal in the last century and fast growing industrialization and urbanization in last few decades have overstrained the natural resource base, which are getting degraded much faster than ever before. Thus, the attention of whole world is focused on how to increase production to feed the burgeoning population and the question uppermost in every ones mind is “how can we produce enough food without damage to the natural resource base, in a sustainable manner?” Precision farming is a promise in this regard. It appears to reduce risk of crop failure (De Boer, 1997).

3.1 INTRODUCTION

Today’s technological advancement has reached a level where a farmer can have access to information and tools to manage mechanized field operations. They can now measure, evaluate and deal variability within field (e.g. soil fertility, water availability and yield) that was known to exist previously but was not manageable, to his advantage. The ability to handle the variation in productivity in the field and maximize financial return, reduce waste and minimize impact on environment has always been objective of an enterprising farmer in horticultural sector, especially those who advocate sound horticultural practices. Since precision farming proposes to prescribe strategic farm management decision in the field operations to help to serve this purpose through mechanization, sensing and communication technology, automate data collection, documentation and utilization of this information. Such an approach in horticultural production management gives rise to what is now termed as precision horticulture, soil specific crop management (SSCM), spatially variable crop production (SVCP), smart farming (SF) etc.

2.1 INTRODUCTION

With increasing population, urbanization and continuous depletion of natural resources, there has to be a paradigm shift in farmer’s perception from production to productivity and to profitability. In the present scenario, the major challenges arising are shrinking land and depleting water and other related resources in agriculture. There is need for promoting farmer friendly location specific production system management technologies in a concerted manner to achieve a vertical growth in horticulture production duly ensuring quality of produce and better remuneration per unit of area with judicious use of natural resources. In this endeavour, precision farming aims to have efficient utilization of resources per unit of time and area for achieving targeted production of horticultural produce. With the revolution in information technology, now it has become possible to focus on the positioning of agricultural tools with high degree of accuracy and sophistication for maximizing returns. The combination of information technology and use of hi-tech equipments made it possible for the introduction of precision farming. It is a comprehensive system designed to optimize agriculture production through the application of crop information, advanced technology and management practices. With recent advances in geographic information systems, it has become possible to focus on site specific crop production technologies so as to harness the potential of horticulture through innovative technologies in a sustainable manner.

1.1 INTRODUCTION

The share of agriculture in GDP is sharp declining. Its share which was 55.1 per cent in 1950-51 came down to 21.6 per cent in 2003-04 and it further reduced down standing barely at 14.6 per cent in 2009-10. Horticulture acconts for 29 per cent share in gross GDP obtained from agriculture sector from about 13.08 per cent area put forth under horticultural plantations (Anon., 2010). To achieve the targetted growth rate of 4 per cent in agriculture, horticulture has to grow at the accelerated growth rate above 7 per cent. As a result of R&D initiatives made, there has been considerable increase in horticultural produce which is acclaimed as golden revoution. Horticulture sector has emerged as the frontier area in dealing with the situation of livelihood security and the employment generation. However, looking to the pressure arising from rising population and erratic climatic variation, more attention is required towards the development of technology driven horticulture. Precision farming is being viewed as a promise in this regard.

Precision farming is the process by which exact or accurate results of farming can be obtained. It is a management strategy that relies upon detailed, site specific information to precisely manage production inputs.

Maximisation of quality yield by managing site variable specific management practices is the basic of precision farming. More emphasis needs to be given to make the farming sustainable. In order to make precision farming a reality the following area needs due consideration.

Postharvest losses of fruits and vegetables are even higher and are estimated to be 40-50%. Postharvest fruit rotting are a major cause of those losses and are chiefly caused by fungal pathogens after fruit ripening. In a manner similar to foliar diseases that occur in the field, several factors as fungal pathogenicity, host response and environment determine the outcome of host resistance or susceptibility. However, in postharvest diseases fruit ripening is another major component that will determine fruit resistance. The molecular trigger induces the germ tube to differentiate an appressorium. It has been shown that excess nutrients over ride it and protein synthesis is not required once germination has occurred. Protein synthesis during conidium germination and appressorium formation on cellulose membranes were observed (Pathak, 1997). A specific polypeptide (95 kDa) was synthesized only when appressoria matured (a period lasting from 12-24 h after germination). This molecule is involved in the synthesis of the melanin precursor, Scytalone.

Appressoria grown in the presence of cyclohexamide do not mature nor they subsequently differentiate a penetration peg. Appressorium maturation involves the formation of melanin. It has been shown that melanization of appressoria is necessary for formation of a successful penetration peg. The melanin appears to give the appressorium mechanical strength, but pigmentation is only one factor required for penetration competent appressoria. At restrictive temperatures, pigmentation of conidia of C. lagenarium mutants could be restored with dihydroxyphenylalanine without restoration of appressorial competence. Non-pathogenic mutants have been used to determine factors important for pathogenicity. Cutinase production was essential for penetration of papaya fruits. The cutinase produced during infection of papaya fruit by C. gloeosporioides has been purified and characterized as a glycoprotein of 24 kDa. Polyclonal antibodies raised against this enzyme do not cross react with cutinase from Fusarium so/ani, and lesions do not develop when papaya fruits are inoculated with spore suspensions containing the antibody preparation.

Postharvest food loss has been considered an unavoidable affliction since food storage first began. These losses are much more painful and costlier in terms of money and man-hours. Such losses due to plant parasitic nematodes, in particular, is severe in tropical regions especially in developing countries like India, where proper storage, transmit and marketing facilities are inadequate. In tropical agriculture, increase in production rate is generally low and, by itself, unable to keep pace with the requirements of the increasing population. Hence, such food shortage demands the need to reduce postharvest loss due to nematodes. Postharvest food losses also constitute a vast complex of physical and biological changes, which makes it very difficult to represent in a single figure. As suggested by different sources, an overall loss of at least 10 per cent occurs in the developing countries. However, the magnitude may range from negligible to cent percent in particular nematode species and crop.

In addition to causing direct losses individually, phytonematodes also favour the establishment of secondary, passive micro- organisms like fungi, bacteria, viruses etc. Nematodes cause mechanical wounds, which serve as avenue for the entry of secondary microorganisms (Ravichandra, 2008). This complex association results in severe damage to planting material.

Postharvest diseases due to nematodes can be managed through restricting the movement of infected planting material to uninfected areas; use of uninfected, healthy planting materials; use of treated planting materials; improvements in the cultural practices at the growing site; timely and careful harvesting; use of nematicides both at pre- and postharvest stages; employment of some physical means like heat, radiation etc; improved storage techniques and integration of these methods. By maintaining hygienic conditions during harvest, transportation, storage and packing most of the postharvest damage due to nematodes can be minimized. Of all the methods, however, regulatory measures like quarantine is more practical and effective in restricting the movement of nematode infected plant materials and contaminated soil into a state or country. Contaminated plant material should be treated (hot water or nematicides) to kill the plant parasitic nematodes before planting to prevent the further postharvest damage. These various measures are primarily aimed at either reduction or wiping out of stages of nematode from the site or protection of host from infection or creation of unfavorable host and/or environmental conditions for the nematodes.

A wide variety of fungal and bacterial pathogens cause postharvest disease in fruits and vegetables. Some of these infect produce before harvest and then remain quiescent until conditions are more favourable for disease development after harvest. Other pathogens infect produce during and after harvest through surface injuries. In the development of strategies for postharvest disease control, it is imperative to take a step back and consider the production and postharvest handling systems in their entirety. Traditionally fungicides have played a central role in postharvest disease control. However, trends towards reduced chemical usage in horticulture are forcing the development of new strategies. Controlling or reducing disease relies on integrated crop and postharvest management, with attention to fungicide application, crop hygiene and nutrition, and the management of ripening, to optimise advantages conferred by the plant’s natural resistance factors that prevent and delay disease development. Agricultural production and food distribution systems have evolved over many years to a complex system which allows for nearly year-round supply of most fresh commodities through longterm storage and long distance shipments to consumers. The expectation of year round supplies has resulted in increased challenges for postharvest handling systems. The availability of fungicides for disease management likely played a major role in the evolution of our current system of food distribution (Mitcham, 1999). With the recent loss of registration of many postharvestfungicides and more expected under the Food Quality Protection Act (FQPA), as well as consumer pressure to reduce the amount of chemicals used on food, the challenge to maintain our current system of food distribution increases.

The potential for significant economic losses from decay caused by postharvest pathogens is greater than is often realized. Harvesting and handling, and the attendant costs for labor and postharvest chemical treatments, can increase the cost of fresh fruits and vegetables several fold from the field to the consumer. Therefore, any produce lost in storage is worth more economically than an equivalent amount lost in the field. Considering economics and the problem of world hunger, it is imperative to understand the importance of postharvest disease and to continually strive to reduce postharvest losses from pathogens. In recent years, many international organizations have identified the necessity of reducing postharvest food losses as an important worldwide goal. While postharvest losses vary from season to season, an average loss of 10% to 30% after harvest is an average estimate. Significantly higher losses are not uncommon in developing countries. The extent of these losses justifies increased research efforts in postharvest pathology (Carl E. Sams, 1994). Chemical treatments and irradiation have effectively reduced the number of microorganisms on various commodities. However, consumer fears associated with chemical residues and the effects of ionizing radiation on fresh produce are forcing the development of alternative protection methods. Also, many pathogens have developed resistance to several commonly used chemicals, while other decaycausing microorganisms currently cannot be controlled by chemicals. Therefore it is better to seek control strategies that will supplement or replace current disease control methods.