Open access peer-reviewed chapter

Hot Water Seed Treatment: A Review

Written By

Suryapal Singh, Harshita Singh and Narender K. Bharat

Submitted: November 20th, 2019 Reviewed: January 22nd, 2020 Published: March 3rd, 2020

DOI: 10.5772/intechopen.91314

Chapter metrics overview

896 Chapter Downloads

View Full Metrics


In present day agriculture, use of chemicals for crop production is discouraged. Hence, other alternative treatments for disease control must be developed, and hot water treatment is one of them. It is a feasible practice, both financially and time wise. Hot water soaking is a very age-old practice, efficient in destroying pathogens borne both outside the testa and inside the seed testa by using temperature hot enough to kill the organism but not quite hot enough to kill the seed. Extensive research work has been reported on hot water treatment in vegetables. Therefore, an attempt has been made to review the information available regarding the effect of hot water treatment on growth, disease incidence and yield of vegetables.


  • hot water treatment
  • capsicum
  • seed-borne disease

1. Introduction

In the present age when the crop production is protected by chemicals and threat of disease due to exposure to these chemicals is at a rise, organic farming is getting momentum. This organic farming is regulated by certain certifications including chemical-free state of agriculture farm. In this condition use of chemicals will not help farmers for these certifications; rather, there is rejection of the produce. Here it becomes pertinent to involve those practices which are natural and can help control diseases naturally. Priming and pelleting are commonly used practices for seed treatment to enhance the production of Capsicum, but some chemicals are involved in it. Capsicum is in great demand as it is a vegetable with very rich contents of vitamins and minerals and is cooked in combination and individually as per the taste of consumers. Rejections of pesticide, insecticide and chemical sprayed crop attracted the attention for the present review where hot water seed treatment is controlling the diseases in bell pepper. Pepper (Capsicum annuum L. var. grossum) is commonly known as Capsicum, Shimla Mirch, green pepper, cherry pepper or bell pepper, and it belongs to the solanaceous group of vegetables. Capsicum is one of the most important vegetable crops grown extensively throughout the world especially in the temperate countries [1] and has attained a status of high value crop in recent years because of its delicacy and pleasant flavour coupled with rich content of ascorbic acid and other vitamins and minerals [2]. Fruits of sweet pepper are either used as salad or cooked as vegetable or processed and is appreciated worldwide for its flavour, aroma and colour. It contains several bioactive substances like capsaicin, vitamin E, pro-vitamin A, carotenoids, flavonoids and other secondary metabolites with antioxidant properties [3]. In the states of Arunachal Pradesh, Himachal Pradesh, Jammu and Kashmir, Darjeeling District of West Bengal and hills of UP, bell pepper is grown in summer, whereas in the states of Karnataka, Tamil Nadu, Bihar and Maharashtra, it is grown in the autumn season [4]. In India, bell pepper covers an area of 29,800 ha with 171,370 tonnes production and productivity of 5.75 tonnes/ha [5]. Sweet pepper is a warm-season crop, which grows well under an extended frost-free season, with the capability of producing high yields of exceptional quality. The best temperature range for sweet pepper growth is 20–25°C, whereas the best germination temperature is 29°C. A temperature of less than 29°C reduces the growth of seedling, leading to increased exposure of seedlings to insects, diseases or salts, resulting in damaged or dead seedlings [6]. High temperatures adversely affect the productivity of many plant species of which sweet pepper is of no exception.

High humidity in the environment and moist soil together with optimum temperature result in high incidence of various diseases. Diseases like bacterial spot (Xanthomonas campestris pv. vesicatoria), Cercospora leaf spot (C. capsici), anthracnose (Colletotrichum capsici) and virus diseases are seed borne in nature. To avoid the occurrence of such diseases, seed treatment with various chemicals has been recommended from time to time [7]. But in present day agriculture, use of chemicals for crop production is discouraged. Hence, other alternative treatments for disease control must be developed. One such treatment is with hot water which is economically as well as temporally feasible. Farmers, along with a little technical assistance, can easily adopt this treatment. This treatment is also successful for destroying viruses like mosaic virus that affect bell pepper. It is very efficient in destroying pathogens borne both outside the testa and inside the seed testa. In this area no such work has been done in the case of bell pepper.


2. Disease of sweet pepper

Bacterial spot (Xanthomonas campestris pv. vesicatoria), bacterial wilt (Pseudomonas solanacearum), anthracnose/ripe fruit (Colletotrichum spp.), Cercospora leaf spot/frog eye leaf spot (C. capsici), bacterial canker (Clavibacter michiganensis) and viruses like Tomato spotted wilt virus (TSWV) are some of the most important diseases of sweet pepper that cause huge economic losses to the farmers. Seed-borne diseases of bell pepper are the most important problems in organic farming systems because of the limitation in chemical control methods. For the successful management of any disease under normal conditions, sanitation, elimination of primary source and chemical protection at initial stages are some of the measures recommended. Various workers are now engaged in developing and testing the non-chemical methods for seed-borne diseases of vegetables including bell pepper.


3. Seed technology

Seed is the primary and essential starting point of a wide range of horticultural crops, including the majority of vegetables. The high-quality seeds of vegetable varieties that display early, consistent, dynamic seedlings and better- and good-quality fruits from individual seed sown at favourable or unfavourable conditions have increased significantly in recent years. Seedling emergence and field stand establishment is one of the problems faced by the growers, especially in early planting where adverse conditions are prevailing (low temperature and high soil moisture). Delayed, erratic germination and emergence, poor stand, slow early seedling growth rate and non-uniform maturity often limit crop production even under optimum environmental conditions [8, 9, 10]. Extensive seed germination and seedling appearance has increased the occurrence of pre-damping off mortality caused by soil-borne fungi [11]. This also leads to establishment of weeds in the fields even before the crop seedlings are mature enough to be cultivated, competing with the main crop for nutrients, and moreover, they hinder the processes of fertilisation, chemical application and mechanical harvesting.


4. Hot water treatment

The most appropriate seed treatment with respect to least damage, economy, efficiency and application is hot water soaking. It is an old-age practice based on treatment with hot water whose temperature is high enough to kill the pathogen but not high enough to harm the seed, hence a very good technique to control many seed-borne diseases [12, 13]. Heat treatment may be applied for agricultural commodities by (1) immersion in hot water, (2) exposure to vapour heat, (3) exposure to hot dry air, (4) treatment with infrared radiation or (5) microwave radiation. Hot water treatments of seed and plant material are classical thermophysical methods of plant protection and are more eco-friendly and effective than chemical treatments.

Hot water treatment can be damaging or not practical for seeds of peas, beans, cucumbers, lettuce, sweet corn, beets and some other crops [12, 14, 15], but it is highly recommended for pepper, eggplant, tomato, cucumber, carrot, spinach, lettuce, celery, cabbage, turnip, radish and other crucifers. It may also severely damage old seeds, and therefore, a small sample of any seed lot over 1 year should be first treated and then tested for germination to determine the amount of injury that may occur. Hot water treatment is recommended for seeds with surface or deep-seated infections. Effective treatment temperature and duration have to be found out for every vegetable crop and the relevant pathogens. The principle is to eliminate the pathogens as far as possible without decreasing germination of seeds. For example, just a 5-min difference in treatment time can lead to diverse differences in the germination rate of cabbage seed.

A number of tests and studies of heat treatment must be undertaken to optimise the time and temperature that are most adaptable to the seeds to be treated and the pathogens to be killed before practical application. Susceptibility to heat damage may differ among different varieties of plant species [16, 17]. The time/temperature combination for a given plant seed depends on many factors interacting with the heat susceptibility of the host, viz., conditions of external layers, dormancy, moisture content, age and vigour [18]. Particularly, it has long been known that the smaller the initial water content of seeds is at the time of heating, the greater the resistance to high temperatures [19]. Two major groups of proteins may be activated by the hot water treatments that induce fruit resistance: heat shock proteins (HSPs) and pathogenesis-related (PR) proteins. HSPs are believed to play a major role in thermotolerance [20, 21, 22]. Among the PR proteins, most characterised enzymes chitinases and β-1,3-glucanases hydrolyse polymers of fungal cell walls and are, therefore, thought to be involved in the plant defence mechanism against fungal infection [23, 24].


5. Effect of hot water treatment on different vegetables

Nega et al. [15] stated that even with longer treatment times, hot water treatment with a temperature of 40°C had no significant effect on the seed-borne pathogens. However, on all the crops investigated, hot water treatments at temperatures 50 or 53°C for 10–30 min had a good phytosanitary effect. In the majority of cases, these treatment conditions did not affect seed germination. Therefore, to reduce the effect of higher temperature like 53°C on germination, comparatively shorter treatment time must be used, especially on sensitive crops like cabbage, etc. The treatment of 50°C for 30 min is optimal against Phoma lingam on cabbage. They also observed that on crops like carrot, cabbage and parsley treatments at temperatures 50–53°C for 10–30 min gave a good elimination of Alternaria species.

In the past, Walker [25] observed complete abolition of P. lingam from cabbage seeds with treatment at 50°C for 30 min. Clayton [26] recorded similar results for 25 min as well as for 30 min at 50°C. Bant and Storey [27] showed good effects of hot water treatment against S. apiicola on celery in field trials. In the view of lack of alternatives, this treatment has proved to be an efficient method on celery and parsley seeds against the Septoria species [28] and that too with well-known yield increase. Due to the rapid spread of bacterial diseases like those caused by Xanthomonas species [29], hot water treatment has emerged as an important method to control seed-borne bacterial diseases because of lack of chemical or other well-established treatments [30, 31]. The documented efficiency of this treatment on cabbage and cauliflower against X. campestris pv. campestris is between 25 and 90%. The treatments differ between 50°C for 10–60 min [32, 33, 34] and 52°C for 30 min [35].

Melanie et al. [36] demonstrated the efficiency of hot water treatment method in reducing bacterial diseases like bacterial spot and bacterial canker in tomato under greenhouse as well as open-field conditions. They also observed that after treating, seedlings from the same seed lots with hot water did not get diseased in the greenhouse or fields. In plots/fields established from hot water-treated seed, the occurrence of bacterial canker was less extensive, and yields were higher than the plots/fields established from non-treated seeds. Also, fruits from non-treated seeds were considerably smaller than fruits from treated seeds. Reduced infection frequency of bacteria responsible for bacterial canker and bacterial leaf spot was observed in tomato seeds after hot water treatment with increased fruit size and yield.

Hot water treatment of seeds of okra (Abelmoschus esculentus) at 52°C for 30 min resulted in the improved crop, both in greenhouse and field conditions. The improvement was with respect to increase in fruit number, leaf number, fruit length and girth, total number of seeds per fruit, seed weight and plant biomass. The hot water treatment of seeds also reduced the frequency of mycoflora infection in the seeds, hence enhancing the vigour index and germination percentage of the seedlings [37]. After soaking carrot seeds in hot water at 52°C for 25 min, the bacterial pathogen (Xanthomonas hortorum pv. carotae) in and on the carrot was killed [38]. On the other hand, Nandini and Shripad [39], observed that hot water treatment at 52°C for 10 min was effective in controlling the bacterial blight of cowpea with minimum number of infected seedlings and percentage of seedling infection. Germination was also not much affected as compared to control (58 vs. 76.00%).

The effects of hot water treatments of carrot seeds on seed-borne fungi, germination, emergence and yield were studied by Hermansen et al. [40] where the seeds infected with Alternaria dauci were hot water treated at temperature ranging from 44 to 59°C at intervals of 5°C for periods of 5–40 min. Treatment of carrot seeds with hot water at 44, 49 and 54°C improved germination rate and reduced the occurrence of A. dauci. Hot water treatment at 54°C for 20 min inhibited A. dauci without negatively affecting germination rate or yield. Ranganna et al. [41] demonstrated that the potato tubers can safely be stored without sprouting for 12 weeks at 8 or 18°C, if treated with 57.5°C hot water for 20–30 min.

Hot water treatment of seeds was also observed to be helpful in controlling seed-borne pathogens in sweet pepper. Aguilar et al. [42] observed that hot water treatment of bell pepper at 45°C for 15 min or 53°C for 4 min before storing them at 8°C reduced the occurrence of fungal infections. Several hot water treatments of bell pepper seeds resulted in considerable drop-off in seed viability but had no effect on seed vigour [43]. No study can be found in the literature that attempted to arrive at the optimum time-temperature combination for sweet pepper. Therefore, the effect of hot water treatments of sweet pepper seeds on seed viability and seedling vigour needs to be investigated (Table 1).

Causal agent Host Thermotherapy tested Result Ref.
Clavibacter michiganensis subsp. michiganensis Tomato (Lycopersicon esculentum) Hot water treatment at 53, 54 and 55°C for 10–60 min Germination remained unaffected up to 55°C for 30 min; bacteria were recovered after 30 min at 53 and 54°C and not after 40 min Bryan [44]
C. m. subsp. michiganensis Tomato Soaking infected seeds 30 min in hot water at 56°C Plants develop significantly less disease than when no seed treatment is used; seed germination is slightly reduced Shoemaker and Echandi [45]
P. s. pv. phaseolicola Bean (Phaseolus vulgaris) Hot water treatments: 50°C for 45–60 min Reduction of bacterial number by 98–l00% but 45% reduction in seed germination for 60 min soaking with naturally infected seeds Tamietti [46]; Tamietti and Garibaldi [47]
P. s. pv. pisi Pea (Pisum sativum) Dry heat at 65°C for 72 h and soaking in water at 55°C for 15 min Significant reduction of pathogen contamination but germination lowered 5–20% Grondeau et al. [48]
P. s. pv. tomato Tomato Infected seeds are subjected to hot water treatment at 48°C for 60 min Pathogens are killed, and germination is not affected Devash et al. [49]
Xanthomonas campestris pv. campestris Cabbage, cauliflower (Brassica oleracea) Hot water treatment at 50°C for 30 min Pathogens are eliminated successfully by this treatment to prevent seedling infestation Shekhawat et al. [34]
X. c. pv. carotae Carrot (Daucus carota) Hot water treatment (52°C for 10 min) Can prevent pathogen infestation Ark and Gardner [50]
X. c. pv. cucurbitae Pumpkin (Cucumis pepo) Hot water treatment at 54 and 56°C for 30 min Greatly reduces the level of seed infestation but does not completely eliminate it Moffett and Wood [51]

Table 1.

Thermotherapy to free seeds from pathogenic bacteria.

Adopted from Grondeau et al. [52].


6. Conclusion

High incidences of disease in consumers leading to fatal diseases like cancer have attracted the attention of researchers. The causative agents were explored, and the focus was indiscriminate use of chemicals starting from seed treatment to crop productions. The residual effects of pesticides, herbicides and other chemicals are long lasting, adversely affecting the health of consumers. Some mechanism and treatments are needed to address these problems. Hot water treatment is one such mechanism which has been reviewed in the chapter to help the consumers taking care of all the public health issues. The present study provides easy to practice technique to farmers without involving cumbersome techniques to farmers to protect the capsicum against bacterial, viral and fungal diseases, leading to optimal productions without harming the interest of consumers.


  1. 1. Manchanda AK, Singh B. Effect of plant density and nitrogen on yield and quality of bell pepper (Capsicum annum L). Indian Journal of Horticulture. 1987;44:250-252
  2. 2. Agarwal A, Gupta S, Ahmed Z. Influence of plant densities on productivity of bell pepper (Capsicum annuum L.) under greenhouse in high altitude cold desert of Ladakh. Acta Horticulture. 2007;756:309-314
  3. 3. Sun T, Xu Z, Wu CT, Janes M, Prinyawiwatkul W, No HK. Antioxidant activity of different colored sweet bell peppers (Capsicum annuum L.). Journal of Food Science. 2007;72:98-102
  4. 4. Singh OP, Anand N, Deshpandey AH. Improvement of bell pepper. Advances in Horticulture. 1993;5:87-104
  5. 5. NHB. Final Area and Production Estimates for Horticultural Crops for 2013-14. Gurgaon, India: National Horticultural Board; 2015. Available from:
  6. 6. Bosland PW, Votava EJ. Peppers: Vegetables and Spice Capsicum. New York: CABI Publishing; 1999
  7. 7. Gupta SK, Thind TS. Disease Problem in Vegetable Production. Jodhpur, India: Scientific Publisher; 2006. pp. 342-346
  8. 8. Cavero J, Ortega RG, Zaragoza C. Influence of fruit ripeness at the time of seed extraction on peppers (Capsicum annuum L.) seed germination. Scienta Horticulturae. 1995;60:345-352
  9. 9. Gerson R, Honma S. Emergence response of the pepper at low soil temperature. Euphytica. 1978;27:151-156
  10. 10. McGrady JJ, Cotter DJ. Anticrustant effects on Chile pepper stand and yield. Horticulture Science. 1984;19:408-409
  11. 11. Ferriss RS, Baker JM. Relationships between soybean seed quality and performance in soil. Seed Science and Technology. 1990;18:51-73
  12. 12. Floyd R. Vegetable Seed Treatments, Farm Note 90/190. Western Australia: Department of Agriculture and Food; 2005
  13. 13. Muniz MFB. Control of microorganisms associated with tomato seeds using thermotherapy. Revista Brassileira Sementes. 2001;23(1):176-280
  14. 14. Miller SA and Ivey LLM. Hot Water Treatment of Vegetable Seeds to Eradicate Bacterial Plant Pathogens in Organic Production Systems The Ohio State University Extension, Columbus, OH Ohio State Extension Bulletin HYG-3086-05; 2005. pp. 3
  15. 15. Nega E, Ulrich R, Werner S, Jahn M. Hot water treatment of vegetable seed—An alternative seed treatment method to control seed-borne pathogens in organic farming. Journal of Plant Disease and Protection. 2003;110:220-234
  16. 16. Lozoya-Saldana H, Merlin-Lara O. Thermotherapy and tissue culture for elimination of Potato Virus X (PVX) in Mexican potato cultivars resistant to late blight. American Potato Journal. 1984;61(12):735-739
  17. 17. Smoot JJ, Segall RH. Hot water as a postharvest control of mango anthracnose. Plant Disease Report. 1963;47(8):738-742
  18. 18. Baker KF. Thermotherapy of planting material. Phytopathology. 1962;52:1244-1255
  19. 19. Waggoner HD. The viability of radish seeds(Raphanus sativus L) as affected by high temperatures and water content. American Journal of Botany. 1917;4:299-313
  20. 20. Howarth CJ, Ougham HJ. Gene expression under temperature stresses. New Phytology. 1993;125:1-26
  21. 21. Sabehat A, Weiss D, Lurie S. Heat-shock proteins and cross-tolerance in plants. Physiologia Plantarum. 1998;103:437-441
  22. 22. Vierling E. The roles of heat shock proteins in plants. Annual Review of Plant Physiology and Plant Molecular Biology. 1991;42:579-620
  23. 23. Collinge B, Kragh KM, Mikkelsen JD, Nielsen KK, Rasmussen U, Vad K. Plant chitinases. Plant Journal. 1993;3:31-40
  24. 24. Schlumbaum A, Mauch F, Vogeli U, Boller T. Plant chitinases are potent inhibitors of fungal growth. Nature. 1986;324:365-367
  25. 25. Walker JC. The hot water treatment of cabbage seed. Phytopatholoy. 1923;13:251-253
  26. 26. Clayton EE. Seed treatment for black-leg diseases of crucifers. New York Agricultural Experiment Station (Geneva) Technical Bulletin. 1928:137
  27. 27. Bant JH, Storey IF. Hot water treatment of celery seed in Lancashire. Plant Pathology. 1952;1:81-83
  28. 28. Merz F. Pflanzenschutztabellen für den Erwerbsgemüsebau. Gemüse. 2000;36:1-39
  29. 29. Poschenrieder P. Pflanzliche Bakteriosen in Bayern– Beobachtungen, Untersuchungen und Erfahrungen in den achtziger und neunziger Jahren. Gesunde Pflanzen. 2000;52:212-220
  30. 30. Koch I, Wahl R, Laun N, Krauthausen HJ, Bauermann W. Bakterielle Blattflecken an Möhren - Bedeutung und Gegenmaßnahmen. Gemüse. 2000;36:28-30
  31. 31. Linders R. Aktueller Wissensstand bei Xanthomonas campestris an Kohl. Gemüse. 2000;36:31-32
  32. 32. Babadost M, Deric ML, Gabrielson RL. Efficacy of sodium hypochlorite treatments for control of Xanthomonas campestris pv. campestris in Brassica seeds. Seed Science and Technolology. 2006;24:7-15
  33. 33. Sha A, Srivastava K, Roy AJ, Bora SS. Control of black rot disease of cauliflower by seed treatment. Progressive Horticulture. 1985;17:72-74
  34. 34. Shekhawat PS, Jain ML, Chkravarti BP. Detection and seed transmission of Xanthomonas campestris pv. campestris causing black rot of cabbage and cauliflower and its control by seed treatment. Indian Phytopathology. 1982;35(3):442-447
  35. 35. Sharma SL. Control of black rot of cauliflower by hot water seed treatment and field sprays with streptocycline. Indian Journal of Mycology and Plant Pathology. 1980;11:17-20
  36. 36. Melanie L, Ivey L, Miller SA. Evaluation of hot water seed treatment for the control of bacterial leaf spot and bacterial canker on fresh market and processing tomatoes. Acta Horticulture. 2005;695:198-200
  37. 37. Begum M, Lokesh S. Effect of hot water and ultra violet radiation on the incidence of seedborne fungi of okra. Archives of Phytopathology and Plant Protection. 2012;45:126-132
  38. 38. Temple TN, Toit LJ, Derie ML, Johnson KB. Quantitative molecular detection of Xanthomonas hortorum pv. carotae in carrot seed before and after hot-water treatment. Plant Disease. 2013;97:1585-1592
  39. 39. Nandini R, Shripad K. Evaluation of hot water treatment on seed germination and seedling infection of artificially inoculated cowpea seeds by Xanthomonas axonopodis pv. vignicola. International Journal of Bioassays. 2015;4(8):4181-4183
  40. 40. Hermansen A, Brodal G, Balvoll G. Hot water treatments of carrot seeds: Effects on seed-borne fungi, germination, emergence and yield. Seed Science and Technology. 1999;27(2):599-613
  41. 41. Ranganna B, Raghavan GSV, Kushalappa AC. Hot water dipping to enhance storability of potatoes. Postharvest Biology and Technology. 1998;13(3):215-223
  42. 42. Aguilar GA, Cruz R, Baez R. Storage quality of bell peppers pretreated with hot water and polyethylene packaging. Journal of Food Quality. 1998;22:287-299
  43. 43. Musazura W, Bertling I. Investigations into the effect of multiple hot water treatment of tomato (Solanum lycopersicum) and pepper (Capsicum annuum) seeds on seed viability and seed vigor. Acta Horticulturae 2013;1007:795-799
  44. 44. Bryan ML. Studies on bacterial canker of tomato. Journal of Agricultural Research. 1930;41(12):825-851
  45. 45. Shoemaker PB, Echandi E. Seed and plant bed treatments for bacterial canker of tomato. Plant Disease Report. 1976;60(2):163-166
  46. 46. Tamietti G. Seed treatment trials to control halo blight of bean. Informatore Fitopatologico. 1982;32(6):47-50
  47. 47. Tamietti G, Garibaldi A. Eradication of Pseudomonas syringae pv. phaseolicola in bean seeds in Italy. In: Quacquarelli A, Casano FJ, editors. Proc. Works. “Phytobacteriology and Plant Bacterial Diseases of Quarantine Significance,” Roma, Italy, 17-21 September 1984. Roma, Italy: Instituto Sperimentale per la PatologiaVegetale; 1984
  48. 48. Grondeau C, Ladonne F, Fourmond A, Poutier F, Samson R. Attempt to eradicate Pseudomonas syringae pv. pisi from pea seeds by heat treatments. Seed Science and Technology. 1992;20:515-525
  49. 49. Devash Y, Bashan Y, Okon Y, Henis Y. Survival of Pseudomonas tomato in soil and seeds. Hassad. 1979;60(3):597-601
  50. 50. Ark PA, Gardner MW. Carrot bacterial blight as it affects the roots. Phytopathology. 1944;34:416-420
  51. 51. Moffett ML, Wood BA. Seed treatment for bacterial spot of pumpkin. Plant Disease Reporter. 1979;63(7):537-539
  52. 52. Grondeau C, Samson R, Sands DC. A review of thermotherapy to free plant materials from pathogens, especially seeds from bacteria. Critical Reviews in Plant Sciences. 1994;13(1):57-75

Written By

Suryapal Singh, Harshita Singh and Narender K. Bharat

Submitted: November 20th, 2019 Reviewed: January 22nd, 2020 Published: March 3rd, 2020