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ID : 85275Ajouté le : 2005-07-21 10:03Mis à jour le : 2005-07-21 10:04Refreshed: 2012-02-11 23:32 
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Document(s) 25 de 38
IntroductionThe impact of the Green Revolution is hardly visible in about 14.9 million ha. of lowland ecosystems of rice in eastern India. Rice, the main staple food of the population, is grown under a wide range of ecological conditions: as an upland crop under great moisture scarcity to a deepwater crop, subject to water depths as high three to four meters. There are many intermediate conditions between these two extremes. In the rainfed lowlands, flood and drought singly or in combination are the major abiotic stresses. So vast is this lowland rice-growing area in Eastern India that it is being increasingly realized at different levels of Indian administration that a large part of the agricultural answers have to come from the region itself. Other regions of the country have achieved fast agriculture growth, while this region has remained static. Better utilization of technology will only come through close analysis of the constraints to the generation and adoption of improved technology as well as analysis involving the formulation of policies.Bihar is a typical eastern state, with highest acreage under rice, 5.4 million ha, and having only 1.2 t/ha average yields. The rainfed lowlands, including the flood-prone ecosystem constituting more than 50% of the total acreage, are characterized by dismally poor productivity. Most of the area is covered by traditional systems of cultivation, though scientists claim to have developed high yielding varietal technologies both at national and state level. Their adoption has been negligible as farmers prefer their own cultivars which are adapted to the varying conditions prevalent in the region. These cultivars have passed through innumerable selection cycles. High yielding varieties perform better where management is better, but virtually fail when conditions are adverse. In this paper, we review the present scenario of high yielding varieties (HYVs) vis-à-vis the traditional genetically-diverse resources, their respective utilization, and describe an approach to develop adapted technologies these rainfed lowlands and flood-prone ecosystems which take account of existing farmer practices. Present system of varietal developmentCrop improvement projects and State Agricultural Universities have a mandate to release varieties with an appropriate package of practices. When a breeder develops a large number of advanced lines at the research station, such lines are initially evaluated and a few best are retained. An even narrower number of entries is promoted to advanced trials. Based on overall performance in yield and other desirable traits, a cultivar is identified for minikit testing, conducted by the State Department of Agriculture. Then again, based on an overall positive performance, the cultivar is named as a variety.Varietal technology developed through this process has mostly been adopted in the risk-free and homogeneous irrigated systems. For the risk-prone rainfed lowlands and deepwater ecosystems, the efficacy of this method appears doubtful. No variety so far developed through this method has been widely adopted. Despite such limitations, this methodology continues to be used and, based on average performance, varieties are being released. It is often assumed that there is a suitable resource base, land tenure system, climatic and infrastructural conditions to suit such component technology. Seldom it is noted that farmers' field conditions are often quite different from those on experimental stations, both in terms of practices and actual agro-ecologies. Farmers' conditions often include dynamic water regions, no insect/pest control, no soil amendments, local practices of cultivation, etc. Improved varieties, consequently, do not manifest their genetic superiority over local varieties under farmers' field conditions (Maurya et al.,1988; Saran et al.,1990). Local cultivar adoption in BiharTable 1 lists the popular local cultivars predominantly grown in different regions of the rainfed lowlands in Bihar. Many high yielding varieties have been released for the lowlands, but their adoption is limited to the favorable, irrigated locales. As we glance over the table, we see that one set of cultivars is popular in one region, another set in another region. No one cultivar is predominately grown in all the regions. Farmers, through their experience, cultivate them in specific situations. Regional adaptability is very obvious. Their choice is mainly based on the average water regime, time of seeding and planting. We may analyze the land situation of a typical Chaur (lowlying land depression, mostly circular or striped in nature). They are deeper at the center and shallow at the periphery. Farmer plant suitable cultivars according to expected water stagnation. At the periphery of the Chaur, short duration varieties, even HYVs, are grown, then photosensitive, tall varieties which can withstand 40-100 cm water depth, and finally floating rices at the center. One can visualize the pattern of water in the Chaur from looking at the varietal composition. Farmers, however, in low rainfall years, such as 1992 onwards, have changed varietal composition; medium duration varieties, instead of photosensitive tall types, are planted now.
Farmers do not always consider the yield as the sole criterion on which to reject or select a culture. The variety must fit into their cropping system, should meet the household requirements and should have practices which farmers can easily afford to apply. The variation in yield due to management and environment should be minimal. In the rainfed lowlands, varieties invariably face drought and/or flood and must have an inherent ability to adapt. This inference has been drawn from the fact that numerous national demonstrations conducted in this environment have amply shown that a higher yield level can be achieved, yet, on practical basis, no farmers grow that variety the next year-- even though they may have realized a higher yield in the past. The reasons for their rejection possibly are (i) high level of management; (ii) necessity for irrigation water; and (iii) input application level, which in the demonstration may have been higher than that available to farmers. We also studied this aspect in our Farming Systems Research Project in a cluster of four representative villages from 1989-1994. This work might serve as a case study on which to plan further work to develop technology for this fragile ecosystem. Targeting the environmentClassifying the environment in relation to the water regime (excess or no water) is difficult to do. There is great yearly variation in terms of flood or drought, rainfall pattern, and type of land depression; such matters complicate targeting for the rainfed lowland/ deepwater ecosystems. There is a high degree of dynamism. The same site may be drought prone if the rainfall is inadequate and or flood prone if the rainfall is heavy. This is main reason that HYVs, when grown in good weather, can yield over average but fail miserably when they face any kind of problem. Local landraces, on the other hand, are adapted to dynamic situations to a much greater degree. They possess adaptability to late sowing and planting, tolerate drought and/or flood and are thermo-sensitive, i.e. tolerance to cold at anthesis.Therefore, we must target the environments based on the varietal choices of the farmers. A set of varieties is being grown in a specific type of environmental context, and that context, when analyzed, was shown to possess a high degree of variation. This indicates that varieties must have ability to adjust a great degree of variation. Bakol, a landrace, was growing in Chauri (lowland) as a transplanted crop and was directly sown in Chauri (deepwater). When there is likelihood of flood, it is directly sown or when there lack of flood, it is transplanted. Varieties possessing a narrow range of adaptability have no future in such an environment. Farmers have, in practice, researched this for years. Intervention and trial designKeeping in view the existing farming systems, on-farm research and on-farm trials were planned as follows. Selected materials generated at the research station were first included in on-farm research trials and, based on their performance, a few were selected for on-farm trials which were conducted over a large number of sites. Farmers were partners in the planning and execution of the trials, which were designed to enable even semi-literate farmers to understand their implications.On-farm research trialEight elite improved rice varieties, differing in maturity and height, along with the local cultivar Bakol were included in this trial (Table 2). The trial sites, one in each village, were selected in cooperation with farmers and the trials were conducted under farmers' management practices. There were three replications, with a plot size of 24 to 30 m2 in a random block design (RBD). The rational of this research trial was two-fold: (i) to offer alternative varietal choices, and (ii) to verify the performance of improved cultures on-farm vis-à-vis the station data. Monitoring was arranged at the post-flowering period jointly with farmers. Based on the performance of entries along yield and maturity criteria, a few entries were selected for specific on-farm trials. This path of rice varietal evaluation, from on-station to on-farm research trial and then to on-farm trial, continued until 1994. Two cultivars, Sudha and TCA 48 in the photosensitive group, like the local Bakol and Rajshree in the earlier maturity group, were identified during the first year itself. They were included in the on-farm trial and, at the same time, remained in the research trial along with other entries (Table 2).
The trial design was simple: the test variety was grown with the local in 500-1000 m2 area under farmers' management practices. The sites, though not very uniform, were mostly on the peripheral portion of the Chaur. Altogether, 54 on-farm trials with Rajshree were conducted. Its performance was rated excellent (Table 3). In drought years of 1990 and 1991, it remarkably did better than the long duration Bakol, which faced severe drought in the absence of rain in September-October. Rajshree, because of its earlier maturity, was virtually unaffected. Sudha was also tried in transplanted conditions against Bakol at 18 locations in three years. It did fairly well over the local but, due to drought in 1991, it also suffered like Bakol. It has, however, a superior grain quality. TCA 48 has now been found better both under transplanted and direct sown conditions. In the drought year, it was significantly superior to Bakol and was also found suitable for delayed sowing and planting. It has now been released as 'Vaidehi' (Thakur et al., 1994.).
ImplicationsThe on-farm data have implications for looking at the two-way linkage between on-farm and on-station research. The rainfed lowlands, which constitutes more than 50% of the rice area in the state, serve as a glaring example where research priorities at the station have had little relevance for actual on-farm situations, both at state and national level. Dwarf varieties, responsive to fertilizer application and record yields, are screened and released-- but they do not match the existing adverse conditions. Mansarowar and Salivahan varieties, released centrally, consequently failed in our on-farm research trials (Table 3). Rajshree, a tall variety, was found successful because it is adapted to late sowing and planting as well as tolerant to drought. It has, however, been released on the basis of its stable yield at research station and, being a spontaneous mutant from the farmers' variety, possibly has adaptation to adverse situations. Criteria such as duration and, to some extent tolerance to submergence and drought, are assessed for rainfed lowlands at the research station but adaptation to delayed sowing/planting, which is the number one problem, is never assessed while selecting a cultivar. At the Eastern India Lowland Breeder's Workshop, held at Bhubneshwar, the author shared his experience of working in farmer fields, which led to the setting up of screening trials for the aforesaid problems in eastern Indian states (Thakur and Mishra, 1992).Rajshree, with about a month earlier maturity than the local, does shows the possibility of developing lies of this duration as envisaged by Choudhury (1982). At present, durations of more than 150 days are the only ones considered. TCA 48, released as Vaidehi, is again a local selection and has advantages over the local Bakol. Varietal release methodThe State Agriculture Universities and Coordinated Crop Improvement Projects have the mandate to release varieties, based on the overall performance of the cultivar at experimental stations and also in minikit testing. Varieties developed through this process have mostly been adopted in the risk-free situations, as mentioned earlier. The rainfed ecosystems have various niches and vary from region to region; varietal adoption is consequently not uniform. For example, varieties suitable for the deepwater Chaur lands of Bihar do not match the requirements in adjoining states like West Bengal and Uttar Pradesh, and vice versa. Farmers, in fact, grow different varieties in different regions. A few varieties, therefore, will not serve the purpose. Release of numerous varieties, rather than a few, has been proposed earlier (Jain and Banerjee, 1982). Therefore, varietal release procedures need to be modified for risk-prone environments.The performance of TCA 48 in farmers' fields under adverse conditions has led its release as Vaidehi, which also has a stable yield at the research station (Thakur et al., 1994). This is a selection from a local cultivar. Pureline selection, though abandoned with the advent of modern varieties and better technical know-how, still has relevance in rainfed ecologies. Jaladhi I and Savita in West Bengal, Kamini and Vaidehi in Bihar have recently been released and have gained popularity in their respective regions. Release will ensure pure seed production and eventually lead to stability in production. This breeding methodology was earlier been suggested, after reviewing the results of the hybridization program (Thakur and Mishra, 1992; Thakur, 1995 ). In a short period of time, it will have a visible impact on the production scenario. However, hybridization has a long-term use in variety release and will ultimately serve to develop varieties adapted to the harsh and dynamic environments (dynamic in respect to water regime, disease/pest pressure and soil deficiencies). North Bihar which used to be largely flood-prone has become now drought-prone for the last four years due to less precipitation. Farmers then started searching for medium duration than long duration cultivars for the upper part of the lowlying Chaur lands. The solution lies in breeding strategies done within the system context, not in isolation but in cooperation and active participation of farmers as partners. We now realize the harsh realities when the HYVs, considered as solutions to all problems, failed to perform. Innovative farmers' techniques, their indigenous knowledge and their overall their active participation in the technology generation is very essential. The participatory approach, advocated earlier, has been found practically useful in identifying farmers-preferred cultivars (Thakur and Singh, 1992, Thakur et al., 1993, Joshi and Witcombe, 1995, Loevinsohn and Sperling, 1995). ReferencesChoudhary, R.C., 1982. Concept of plant type for rainfed lowland rice in India. Task force meeting on Rainfed lowland Rice. November 12-13, Rajendra Agricultural University, Patna.Jain, H.K.. and S.K. Banerjee, 1982. Problem of seed production and varietal release in India. Seed Research, 10:1-7. Joshi, A and J.R. Witcombe, 1995. Farmer participatory research for the selection of rainfed rice cultivars. Proceedings of the IRRI Conference 1995. Fragile lives in fragile ecosystems. Los Banos: International Rice Research Institute (in press). Loevinsohn, M.E. and L. Sperling, 1995. Using diversity: conserving crop genetic resources by meeting farmers' needs. National Seminar on biodiversity conservation, Asian Development Research Institute, Patna, February 18-19, 1995. Maurya, D.M., A. Bottrall, and J. Farrington, 1988. Impact livelihood, genetic diversity and farmers' participation: strategy for rice-breeding in rainfed areas of India. Experimental Agriculture, 24:311-320. Saran, S., K.C. John, A. Kumar, S. Ahmad, M.M. Singh, and P. Mishra, 1990. Incremental method for developing integrated farming system in high ecological risk zones. Asian Farming Systems Research and Extension, Symposium on Sustainable Farming Systems in the 21st Century. Bangkok: AIT. Thakur, R. and A.K. Singh, 1992. Impact assessment of successful on-farm trials. Asian Farming System Research and Extension Symposium, Colombo, November 6-8, 1992. Thakur, R. and S.B. Mishra, 1992. Rainfed lowland in Bihar. Status of varietal development and breeding strategy. Eastern India Breeder's Workshop, Bhubneshwar, March 9-10, 1992. Thakur, R., A.K. Singh, and R.S. Singh, 1993. Sustainable technology for rainfed lowland rice ecosystem through FSR linkage with on-station research. Rice-based Farming System Technology Exchange, Philippines. Thakur, R., S.P. Sahu, A.K. Singh, R.S. Singh, and N.K. Singh, 1994. Vaidehi, a variety for rainfed lowland conditions in Bihar India. IRRN 19:1. Thakur, R. 1995. Prioritization and development of breeding strategies for rainfed lowland: A critical appraisal. Proceedings of the IRRI Conference 1995. Fragile lives in fragile ecosystems. Los Banos: International Rice Research Institute (in press). Footnotes:1 Chief Scientist (Rice) and University Professor, Department of Plant Breeding, Rajendra Agricultural University, Bihar, Pusa (Samastipur), 848125. While unable to attend the conference, the author submitted the following paper. (BACK)
Document(s) 25 de 38
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