Seed priming in mungbean and chickpea strengthens disease resistance |
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Chickpeas sown from primed seed in farmers' fields in Bangladesh have proved to be more resistant to collar rot than chickpeas from seed that was not primed. Likewise, primed mungbean proved resistant to Mungbean Yellow Mosaic Virus in Pakistan. Then, tests in glasshouses showed that primed pearl millet was resistant to Downy Mildew. All this means that priming helps prevent serious damage to pea and bean crops from common diseases. Farmers in the High Barind Tract of Bangladesh and in eastern India now readily prime chickpea seed. They've seen for themselves that primed chickpeas are more resistant to disease than those that aren't primed. Project Ref: PSP29:
Research Programmes: Plant Sciences Research Programme (PSP). Relevant Research Projects: R7438, R8269, R8221
Seeds of many crops can be primed - soaked in water overnight before sowing -to improve germination, seedling emergence and vigour, growth and yield. Observations in farmers' fields suggested that, in some circumstances, primed crops suffered less damage from some pests and diseases than crops grown from non-primed seed. Field studies between 1999 and 2006 of chickpea and collar rot (Sclerotium rolfsii) in Bangladesh and mungbean and Mungbean Yellow Mosaic Virus in Pakistan confirmed that seed priming could increase resistance to those diseases. We also showed that priming pearl millet seeds could increase resistance to Downy Mildew (Sclerospora graminicola), at least under glasshouse conditions, although additional studies to identify the physiological mechanism involved in this response have so far proved inconclusive. It is unlikely that commonly observed yield increases in a wide range of crops from primed seeds are solely the result of increased disease resistance. However, it may be that small increases in resistance contribute 'unseen' in many situations where disease pressure is present at a low level. In addition to promoting innate disease resistance, priming can also be used as a vehicle to treat seeds with crop protection chemicals such as fungicides.
The studies described in this document apply to:
Other reports, such as those involving rice and Rice Blast, remain unconfirmed
Farming Systems:
This is a cost-effective output that could contribute to crop productivity in general but would be particularly appropriate to take forward with other IPM-related outputs such as those listed below:
How the outputs were validated: Indian farmers reported that primed chickpea suffered less damage from pod borers (Harris et al. 1999) and damage in Bangladesh was much reduced but the apparent difference was not statistically significant (Musa et al., 2001). However, damage in farmers' trials caused by collar rot (Sclerotium rolfsii) in Bangladesh was significantly reduced by priming seeds overnight, by 45 % in 1998-99 (30 trials) and by 30 % in 1999-00 (35 trials) (Musa et al., 2001). In an on-station trial in Peshawar, Pakistan in 2002, Rashid et al. (2004a) showed that priming seeds of mungbean cv. NM 92 for 8 h in water resulted in a significant five-fold increase in grain yield relative to a non-primed crop. This was associated with a large difference in the severity of symptoms of mungbean yellow mosaic virus (MYMV) assessed using a visual scoring index. More than 70 % of the non-primed plants had severe or lethal symptoms whereas only 14 % of the primed plants were similarly affected. Only 9 % of non-primed plants showed no disease symptoms in contrast to 32 % of primed plants. Rashid et al. (2004b) also observed similar differences in MYMV infection in other on-station mungbean priming trials. Downy mildew disease, caused by the obligate biotroph Sclerospora graminicola (Sacc.) Schroet. is a major constraint to pearl millet yields. A standard greenhouse screening method (Jones et al., 1995) was used to investigate the effect of seed priming on the disease resistance of pearl millet. Priming seeds in water for 8 h before sowing significantly reduced the incidence of downy mildew disease in seedlings of a highly susceptible cultivar from about 80 % to less than 60 % (Harris et al., 2005). The effect was confirmed in additional glasshouse experiments (unpublished). Although the screen would not allow plants to be assessed at later stages of growth, there is a high degree of correlation between performance of cultivars in the screen and their resistance to downy mildew in the field (Jones et al., 2002). However, a preliminary trial at ICRISAT, India in 2006 failed to confirm this effect in the field. Where the Outputs were Validated: The effect on disease resistance has only been validated quantitatively by 65 farmers with chickpea in Bangladesh in two seasons (1998-1999 and 1999-2000) although a total of 280 farmers compared primed- with non-primed chickpea using paired-plot trials between 1998 and 2002 in rice-fallows of the High Barind Tract (semi-arid smallholder and sharecropper, rainfed dry). Effects in other crop-disease systems have only been validated in replicated on-station trials (mungbean for semi-arid, smallholder, rainfed dry) and under glasshouse conditions (pearl millet, usually grown in semi-arid, smallholder, rainfed dry systems). Who are the Users? Any disease alleviation due to priming is included in the overall positive priming effect where crops are primed but is not currently explicitly recognised. Priming chickpea seed is a common practice in Bangladesh (Saha, 2002; Socioconsult, 2006) and in eastern India (Kankal et al., 2006) and it is possible that enhanced disease resistance is contributing to the increased yields associated with priming. Similarly, some farmers in Pakistan are priming mungbean seeds so may be benefiting from the same effect. Where the outputs have been used: In theory, if the effect is a real one, it is benefiting farmers wherever they are using primed chickpea seeds and there is disease pressure. If the effect operates in other crop/disease systems then it might be contributing to priming-related yield increases everywhere. Without further specific studies it is difficult to quantify any benefits. Scale of Current Use: Priming of chickpea seed was rapidly adopted in the High Barind Tract of Bangladesh (Saha, 2002; Socioconsult, 2006) and in eastern India (Kankal et al., 2006), not because of its specific effects on disease but because of the overall positive effect of priming, which is mainly considered to be improved crop establishment under sub-optimal soil moisture conditions. Rapid spread of the technology will depend on the continued popularity of chickpea as a second crop after rainfed rice and the intensity of promotion efforts for chickpea. Priming of mungbean in Pakistan is only done by a small number of farmers. Policy and Institutional Structures, and Key Components for Success: Farmers have adopted seed priming in chickpea because of its overall benefits, with reduced losses due to disease only one component of that. Successful promotion was a result of making farmers aware of the potential benefits of priming then facilitating them to test the idea for themselves. Existing institutions, e.g. the Department of Agricultural Extension in Bangladesh, can do this effectively if they foster the close linkages with communities espoused by NGOs such as PROVA and use participatory Action Research (PAR). More research on the effects of priming on diseases of other crops would be useful. Lessons Learned and Uptake Pathways Promotion of Outputs: Priming specifically to alleviate disease is not currently being promoted. Potential Barriers Preventing Adoption of Outputs: Increasing disease resistance is only one of the reasons why seed priming is attractive to farmers, so it is difficult to promote on that basis alone. How to Overcome Barriers to Adoption of Outputs: A focussed research programme to quantify effects of priming on disease across crops and locations. Lessons Learned: It is unlikely that seed priming can be promoted on the basis of increased disease resistance alone. For seed priming technology in general, one of the best ways to get to a large number of farmers is to link the technology to a PVS programme. Experience has shown that farmers are very keen to try new varieties. By giving improved cultivars to farmers and asking them to prime some of the seeds they can see the direct and indirect effects for themselves, thus leading to adoption. Use of participatory methods, such as farm walks and field days, is very useful in the validation of the technology as they allow farmers to observe it in a range of familiar situations and can facilitate the effective use of farmers' feedback in fine-tuning it. Participatory approaches also break down barriers between scientists, extension agents and farmers. Seed priming is an enabling technology - helping to ensure good stands of vigorous plants - and, as such, is an important component of an integrated approach to crop production. Holistic approaches to agricultural development, such as those pursued in rural development programmes or through Farmer Field Schools would be an ideal vehicle for promoting seed priming because its effects open up additional opportunities to apply other technological innovations, such as low-risk use of fertilizer. Poverty Impact Studies: No impact studies have been done specifically on the effects of priming on disease resistance. Impact studies from Bangladesh and India in relation to elements of chickpea production, including priming are: Saha, A.K. (2002). Impact assessment study for the DFID-funded project R7540 'Promotion of Chickpea following Rainfed Rice in the Barind Area of Bangladesh'. CAZS Natural Resources, University of Wales, Bangor, UK. Socioconsult (2006). Report on Impact Assessment Study of Chickpea in the High Barind Tract (HBT). Socioconsult Ltd., SEL Centre, 29 West Panthapath, Dhanmondi, Dhaka. Kankal, M., Basu, I., Gupta, B., Mishra, K., Gupta, A., Peter, R. and Dash, P. (2006). Agricultural Alternatives - Experiences of Rainfed Rabi Cropping in Rice fallows of India. Catholic Relief Services-USCCB, October 2006. pp 33. How the Poor have Benefited (including gender and other poverty groups): There is no evidence as yet of benefits to the poor from priming specifically through reducing disease in crops. It is possible, however, that benefits due to priming in general will have a component of enhanced disease resistance. Direct and Indirect Environmental Benefits: Benefits would include less need for agricultural chemicals to manage disease, with decreased production costs and fewer opportunities for human toxicity to farmers and consumers. Reduced disease incidence in legumes, leading to higher yields, would promote beneficial "legume effects" such as improved soil health and fertility. Adverse Environmental Impacts: No adverse effects envisioned. Coping with the Effects of Climate Change, or Risk from Natural Disasters: Climate change is likely to change disease patterns, with possible epidemics of new diseases. Priming may be able to help poor people manage these, without increasing reliance on agro-chemicals. References Harris, D., Joshi, A., Khan, P.A., Gothkar, P. and Sodhi, P.S. (1999). On-farm seed priming in semi-arid agriculture: development and evaluation in maize (Zea mays L.), rice (Oryza sativa) and chickpea (Cicer arietinum) in India using participatory methods. Exp. Agric. 35: 15-29. Harris, D., Breese, W.A. and Kumar Rao, J.V.D.K. (2005). The improvement of crop yield in marginal environments using 'on-farm' seed priming: nodulation, nitrogen fixation and disease resistance. Australian Journal of Agricultural Research 56 (11): 1211-1218. Jones, E.S., Breese, W.A., Liu, C.J., Singh, S.D., Shaw, D.S. and Witcombe, J.R. (2002). Mapping quantitative trait loci for downy mildew resistance in pearl millet: Field and glasshouse screens detect the same QTL. Crop Sci. 42: 1316-1323. Jones, E.S., Liu, C.J., Gale, M.D., Hash, C.T. and Witcombe, J.R. (1995). Mapping quantitative trait loci for downy mildew resistance in pearl millet. Theor. Appl. Genetics 91: 448-456. Kankal, M., Basu, I., Gupta, B., Mishra, K., Gupta, A., Peter, R. and Dash, P. (2006). Agricultural Alternatives - Experiences of Rainfed Rabi Cropping in Rice fallows of India. Catholic Relief Services-USCCB, October 2006. pp 33. Musa, A. M., Harris, D., Johansen, C. and Kumar J. (2001). Short duration chickpea to replace fallow after aman rice: the role of on-farm seed priming in the High Barind Tract of Bangladesh. Experimental Agriculture 37 (4): 509-521. Rashid, A., Harris, D., Hollington, P.A. & Ali, S. (2004a). On-farm seed priming reduces yield losses of mungbean (Vigna radiata) associated with mungbean yellow mosaic virus in the North West Frontier Province of Pakistan. Crop Protection 23: 1119-1124. Rashid, A., Harris, D., Hollington, P.A. & Rafiq, M. (2004b). Improving the yield of mungbean (Vigna radiata) in the North West Frontier Province of Pakistan using on-farm seed priming. Experimental Agriculture 40 (2): 233-244. Saha, A.K. (2002). Impact assessment study for the DFID-funded project R7540 'Promotion of Chickpea following Rainfed Rice in the Barind Area of Bangladesh'. CAZS Natural Resources, University of Wales, Bangor, UK. Socioconsult (2006). Report on Impact Assessment Study of Chickpea in the High Barind Tract (HBT). Socioconsult Ltd., SEL Centre, 29 West Panthapath, Dhanmondi, Dhaka. Relevant Research Projects,
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