Keeping in view the importance of vegetables in both food and nutrition security, it becomes necessary for the nation to ensure sustainable vegetable production. Presently, the vegetable production is neither sufficient and stable in its supply nor adequate to meet nutritional standards. This is due to low crop productivity, inadequate water resources, erratic rains, and natural disasters such as typhoons and floods.
While area expansion may not be easily possible, it would not be difficult to increase crop productivity. Higher production can be obtained with the help of improved varieties and F1 hybrids, advanced agro-techniques, adequate water resources, water management and improved plant protection methods. In view of the fact that the national requirement for vegetables is likely to increase in the coming decades, to keep pace with the rising population, research priorities and programmes have to be reoriented and intensified, specifically with respect to need-based applied research. The varietal improvement should be targeted mainly towards breeding for resistance to diseases and insect pests, earliness and better keeping quality and transportability. Varieties have to be developed also for abiotic stresses, especially suitable for various agro-climatic conditions, like rainfed conditions, heat tolerance and problem soils (saline and alkaline). Early maturing varieties will fetch higher prices in the market than normal varieties, and in some cases these may escape the attack of a disease or insect. Efforts may be concentrated to identify genetic sources of resistance within both indigenous and exotic germplasm. Germs for disease resistance may be incorporated into the existing varieties through protoplast fusion/sotuatic hybridization, recombinant DNA technique and coat-protein in case of virus diseases. However, the development of transgenics should invariably be taken up under an appropriate regulatory system within the country. Breeding for heat tolerance in cabbage, cauliflower, onion, carrot, lettuce and tomato also needs to be emphasized.
It is essential to undertake collection, conservation, evaluation and documentation of the existing biodiversity of the common native vegetables before these are lost. Domestication, cultivation and improvement by conventional breeding methods is useful. A similar approach is required in the case of under-utilized vegetables, especially those which have a wide distribution in nature in the Southeast Asian region, like coccinia, bitter gourd, luffa, wax gourd, amaranthus, horseradish tree (Moringa oleifera). In addition, a genetic base could be enlarged through the introduction of germplasm particularly from Asian countries (Nath, Velayudhan and Singh, 1994).
With the use of F1 hybrids, crop productivity can be increased manifold within a short period. Besides, hybrid cultivars have other useful attributes too, like disease resistance, earliness, better keeping quality and transportability. Development of F1 hybrids should receive priority in crop breeding programmes. It may include development and utilization of male sterility, genic (GMS) and Cytoplasmic (CMS) self-incompatibility and gametocide induced male sterility.
Hybrid cultivars require better production technology than common OP cultivars, which is necessary for exploitation of their maximum potential. Undoubtedly, seeds of hybrid cultivars are expensive, but provide at least two to three times higher economic returns from their yield and quality as compared to open pollinated cultivars. Besides, the cost of F1 hybrid seeds is only six to ten percent of the total production cost. By adopting improved methods of seed germination and raising seedlings often under protected environment, it has been possible to drastically reduce the seed rate per acre.
Priority may be given to develop appropriate and cost-effective agro-techniques, including bio-fertilizers, integrated nutrient management, water management etc. suitable to different agro-climatic and soil conditions and cropping systems in a few selected vegetables. The effort should be made in order to narrow down the existing wide gaps between farm yield and potential yield.
Raising seedlings in low polyethylene or netted tunnels, in polygreenhouses or in insect-proof net houses will be beneficial in obtaining healthy seedlings sufficient to maintain the desired plant density with almost negligible seedling mortality in the field. It will also help in raising an early crop. Protrays may also be used for sowing of seeds. Perhaps it may be worthwhile to develop greenhouse technology for growing vegetables under a protected environment, like polygreenhouse and insect-proof net house, with proper ventilation and air circulation but without cooling, similar to those used in Israel, Spain and other countries. Protected cultivation will be helpful in getting an early and off-season crop.
Farmers often indiscriminately use chemical pesticides to control diseases and insect pests in vegetable crops, resulting in environmental pollution and heavy residual toxicity most harmful to humans and animals. The multiplicity of diseases and insect pests in most of the vegetable crops makes it difficult to effectively control them. Integrated Pest Management (IPM), though useful in minimizing the use of chemicals, has unfortunately not proven its success in vegetable cultivation in the open in many developing countries because of small holdings, intensive cultivation, several crops grown in the same season, and numerous diseases and insect pests. Nevertheless, it may be useful to take up research on IPM using various methods including predators and parasites, bio-pesticides etc. in a few important vegetable crops. A bio-pesticide like Trichogramma is useful in controlling soil-born fungi like Pythium and Rhizoctonia in the nursery. Botanical or plant derived pesticides, like neemicide from neem, and a few others, have been found to be useful in controlling insect pests. Neem kernel extract has been reported to be effective against diamond back moth, which is a serious pest of cabbage, cauliflower and other crucifers in Asian countries, including Thailand. Trap crops are also useful in controlling this pest. Planting mustard around the cabbage field, or planting a few rows of it in between the rows of cabbage, minimizes the damage caused by the diamond back moth. Investigations on such aspects would prove useful.
The recently launched organic farming project in Bangkok by His Majesty the King of Thailand is commendable. Organically grown vegetables have a great potential for export, besides sale in domestic markets. However, many aspects of the organic farming system have to be studied in detail and standardized e.g. utilizing composts, greenhouse, oilcakes, bonemeal, vermiculture, bio-fertilizers (azetobacter and others), bio-pesticides etc. Besides, the cost-effectiveness of this system is equally important. In organic farming the general experience of farmers is that initially it takes at least three years to attain normal crops yields. Nevertheless, organic farming is a challenging venture.
Vegetables, being perishable, are subject to heavy losses after harvesting and during transportation. The post-harvest losses in vegetables are about 30 percent in Thailand. However, post-harvest handling of vegetables for processing and export by contract growers in commercial farms is better, with less wastages than in small-scale farming. Research on post-harvest technology may be focussed on physiological, pathological, entomological and engineering aspects, with a view to developing a package of practices to be adopted by small as well as large scale farmers. This technology should be simple, cost-effective, efficient on both small and large farms and dependable on different agro-climatic conditions.
Since most of the vegetables are perishable, cold storage facilities on farms and market outlets should be provided to reduce post-harvest losses. It will also enable the transportation of fresh vegetables from centres of excess production to deficit areas or to distant markets in large cities which have higher demands. Refrigerated vans for transport are necessary in such cases. The government should consider providing subsidies to farmers for cold storage and refrigerated vans, if possible. Furthermore, the public sector may encourage the formation of cooperative societies of farmers, preferably involving small farmers in contract farming. The cooperative society may also collect the vegetables from farms, grade them, store them in cold storages and transport them in refrigerated vans to market outlets in cities from where they may be sold directly without any involvement of wholesalers and middlemen. The cooperative society may establish a network of air-conditioned kiosks or shops in the city for selling vegetables at a pre-fixed price daily to consumers. It would ensure stability of supplies and prices of fresh vegetables of good quality, which will benefit both the growers and the consumers. To begin with, such a venture may be taken up in Bangkok and if successful, it may be adopted in other cities.
Seed is the basic need for any crop production programme. In Thailand, vegetable seeds of both open pollinated varieties and hybrids are supplied (75 percent) by about 50 private seeds companies and only five percent is supplied by the public sector. The rest, 20 percent, is from seeds saved by farmers. All important aspects of seed technology require intensive studies. Standardization of seed production techniques, especially with respect to hybrid seed production, deserves special attention. Other studies may include advanced methods such as: electrophoresis, DNA makers, DNA-fingerprinting etc. for testing the genetic purity of parent, hybrid, and open pollinated varieties.
A few other techniques, like seed coating, pelleting, enhanced seeds, pre-germinated seeds, seed colouring etc., as well as methods of seed storage and packaging using different types of packing materials etc. may be worth investigating for their usefulness in the country.
Seed certification standards may be formulated which are to be followed by all seed producers. An independent seed certification agency/authority may be set up. It is always necessary to have an independent seed certification system separate from seed production agencies.
The public sector may consider expansion of the present production of vegetable seeds, which is only five percent of the total seed requirement. Since there are already good infrastructure facilities available, it should not be difficult to organize large scale seed production within the country. This will also be useful in popularizing some of the good varieties already developed by government institutions among local farmers. Seed production for temperate vegetables (onion, carrot and crucifers) would, of course, be limited to the cooler regions of the country.
The public sector seed production will be helpful in import substitution to a great extent, save foreign exchange, provide gainful employment opportunities to young men and women in rural areas, especially in the case of labour intensive hybrid seed production, besides providing remunerative and stable income to small contract growers. The other advantage will be that farmers can depend on the performance of seeds of the varieties adapted to local agro-climatic conditions. It is also necessary to test the performance of imported varieties or hybrids in different agro-climatic conditions. Large quantities of seeds are allowed to be imported by the government. It will also be in the national interest to get the seeds of the best performing varieties or hybrids produced by foreign companies, into the country. The import substitution of vegetable seeds and their production in the country may be taken up in a phased manner.
The export of F1 hybrid vegetable seeds produced within the country by private seed companies may be encouraged in view of the fact that, it is not only remunerative to farmers, but also being labour intensive it generates employment opportunities in rural areas, besides bringing in much- needed valuable foreign exchange into the country. Similarly, export of both fresh and processed vegetables should be encouraged and expanded, if possible. The potential for the export of organically grown vegetables may be explored and encouraged in the future. The export of seeds, as well as of fresh and processed vegetables grown on commercial farms which adopt high standards of production and quality control, will prove helpful in upgrading the production technology and quality of local production.
The marketing of perishable vegetables is a difficult task in most of the developing countries. The main constraints are unstable supplies, uncertain demands, highly fluctuating prices, inadequate storage facilities, and problems in the long distance transportation of vegetables from production centres to distribution outlets in cities. Weather forecasting will be useful to farmers in vegetable growing regions, especially in those where weather is often uncertain such as in the more erratic southern and central regions. Similarly, market intelligence and forecasting is necessary to monitor demands, and thus help the farmers in efficient crop planning. A well-regulated marketing channel is required to avoid shortages, discourage hoarding, and to control prices in the market to a great extent. The market information service, with the help of modern information technology, can be easily made available to farmers and planners. On the basis of the weather and market information available, the government may undertake crop planning region-wise, by convening regular meetings with extension and development staff before the start of each crop season. This planning would also be necessary to ensure adequate supply of seeds to farmers. In the absence of a database, crop planning may be difficult but, it would be useful for the national interest.
Human resource development is an important foundation block for building any institution or programme. In the foregoing chapters, the relevance, importance and contribution of vegetables to food security have been discussed and highlighted. In order to maintain and improve upon activities of the vegetable sector, staff development in research, extension, and marketing will be essential. To ensure continued research, highly qualified personnel with M.S. and Ph.D. degrees in different disciplines, particularly breeding, agronomy, entomology, pathology, processing and biotechnology, are a pre-requisite to the success of research projects. To cater to the needs of the crop fields and farmers, well-trained officers would be required to train the middle-level technicians or extension workers with high school or agriculture diplomas, who, in turn, will train the farmers. Thus, an appropriate forward-looking human resource development strategy and plan need to be developed, looking into the foreseeable future and the requirement of the personnel at higher, middle and lower cadres covering all administrative regions of the country. This plan should take into consideration both the quality and quantity aspects of production to facilitate development of the vegetable sector in the country.
On the one hand, there are significant gaps between potential yields and actual on-farm yields or between experimental plots and farmers fields which need to be bridged. On the other hand, problems emanating in the field should be identified by the extension officers and brought to the attention of the researchers for developing appropriate solutions. Hence, strenghtening of linkages between the institutions and officials of research and extension can ensure better results.