Effect of weather parameters on severity of Alternaria blight of cumin caused by Alternaria burnsii in rajasthan

Introduction

Cumin (Cuminum cyminum L.) is believed to be originated from Mediterranean and near Eastern regions of the globe (Nabhan, 2014) [16] . India ranks first in terms of the acreage and production. Within India, it is extensively cultivated in Rajasthan, Gujarat and in some parts of Madhya Pradesh as rabi crop. Cumin is very popular and important among seed spices crops like coriander, fennel, fenugreek, Ajwain etc. The element in amount/100 g present in cumin contains energy 375 Kcal, carbohydrates 44.24 g, sugars 2.25 g, dietary fibers 10.5 g, fat 22.7 g and protein 17.81 g (Rai et al., 2012) [17] and also contain 7.7% minerals and vitamins (vitamin-A, vitamin B1, B2, B3, vitamin-C etc.) (Shankaracharya and Natarajan, 1971; Chadha, 2006) [18,2] . It is also used in food and beverages industry as spice and condiment. Cumin is generally grown as a mono crop. The increasing population load and globalization has created high demand of cumin both in domestic and international markets. There is need to enhance the productivity levels to meet the increasing demand. The principal constrains to achieve high productivity are high yielding varieties, improper nutrient management and susceptibility of cumin to devastating diseases. The climatic conditions found in the two states of Rajasthan and Gujarat are more favorable for cumin cultivation, these two states contribute more than 80% in National area and production status. In India, cumin is grown as a Rabi crop, typically planted in October-November and harvested in February-March. Ensuring the proper seed rate is vital to achieve the desired plant population and maximize cumin production. The seed rate varies depending on the variety and planting method, with an ideal rate of 12 to 15 kg per hectare for cumin. Cumin thrives in a moderately cool and dry climate, with optimal temperatures ranging from 25 °C to 30 °C. Although it is a tropical plant, cumin can also grow well in a sub-tropical climate. Harvesting typically begins in the first week of March, depending on the planting date, with seeds being ready for collection around 110-120 days after sowing (DAS).

Cumin seeds can be separated by beating them on a clean threshing floor or using a cumin threshing machine (Malhotra and Vashishtha, 2008) [13] . This spice crop is subjected to many pathogens causing diseases which negatively influences the yield (Dange, 1995; Sharma et al., 2010) [4,19] . Cumin is highly susceptible to fungal diseases, especially when there is high humidity during flowering and fruit set. These diseases significantly affect the crop health. The plant is also very sensitive to rain, particularly during the harvesting period, as rain can lower both yield and quality. Frost damage is another major threat, especially during flowering and early seed formation. Cumin cannot tolerate shade and is extremely sensitive to any weather changes. For proper storage, dried cumin seeds should be kept in moisture-proof containers, away from direct sunlight. Factors such as fungal diseases, improper sowing dates, and successive planting are major contributors to reduce the cumin yield. Fungal diseases account for 38% of the yield reduction, while the sowing date contributes 30% and successive planting contributes 5% (Kamkar et al., 2011) [10] . The average yield of cumin crop is low because of various factors such as non-availability of superior varieties, inappropriate crop production practices and susceptibility to diseases like Alternaria blight (Alternaria spp. Uppal, 1933) [21] , Fusarium wilt (Fusarium oxysporum f. sp. cumini Gaur, 1949) [6] and powdery mildew (Erysiphe polygoni D. C. Burns, 1921) [1] . Among various biotic stresses, Alternaria blight of cumin incited by Alternaria spp. is second most economically important disease after wilt. The disease was first noticed to be caused by Alternaria spp. from Bombay province and the causal agent was identified as Alternaria burnsii (Uppal et al., 1938). In Rajasthan it was reported by Joshi (1955) [9] .

Materials and methods

The experiment was conducted to investigate the effect of weather factors on the development of cumin blight on the susceptible cumin cultivar GC-4 during the Rabi seasons of 2022-23 and 2023-24 at the instructional Farm, Rajasthan College of Agriculture, Udaipur. Sowing of the susceptible cumin variety GC-4 was carried out in the 3 rd week of November during both years. After germination, 40-day-old plants were inoculated with a spore suspension of Alternaria burnsii at a concentration of 2×10 6 conidia/ml. Disease severity was recorded from the initiation of symptoms and at seven-day intervals, using the 0-5 rating scale given by Jaiman et al., (2013) [8] . Various weather variables such as temperature, relative humidity (RH), and rainfall were recorded throughout the crop season, and their correlation with disease development was analyzed. The percentage disease intensity (PDI) was calculated for each reading until the crop reached maturity.

Number of infected plants

Weekly meteorological data, including maximum and minimum temperature, morning and evening relative humidity, and rainfall, were obtained from the meteorological observatory at the instructional Farm, Rajasthan College of Agriculture, Udaipur.

Results

The first observation on per cent disease incidence was recorded during the first meteorological week (1-7 January) of each crop season and continued until the eleventh meteorological week (12-18 March). A total of eleven observations on disease incidence were recorded during both crop seasons. The data showed that the mean disease intensity ranged from 0.00 % -36.38 % in tested cumin variety GC-4 during 1 st to 11 th meteorological week of Rabi season 2022-23 and it was observed 0.00 % -25.94 % mean disease intensity during 1 st to 11 th meteorological week of Rabi season 2023-24.

During the period (Rabi 2022-23), average maximum and minimum temperatures ranged from 22.5 °C to 33.9 °C and 3.1 °C to 13.4 °C, respectively. The average morning relative humidity ranged from 62.1% to 83.7%, and the evening relative humidity ranged from 24.1% to 72.8%.

During the period from the first to the eleventh meteorological week of Rabi 2023-24, the average maximum and minimum temperatures ranged from 23. 1). The results for disease intensity of Alternaria blight showed significant variation with allweather variations. The data showed that the value of r (0.637 and 0.646) for maximum and minimum temperature was found significant with positive correlation, value for r (-0.551) for relative humidity during morning hours was found significant with negative correlation and value of r (0.350) for relative humidity during the evening hours was found significant with positive correlation with PDI and value of r (0.195) for rainfall was found significant with positive correlation with PDI.

During Rabi 2023-24, the observation with respect to progression of disease intensity of Alternaria blight was recorded (Table 2). The results for disease intensity of Alternaria blight showed significant variation with allweather variations. The data showed that the value of r (0.673 and 0.569) for maximum and minimum temperature was found significant with positive correlation, value of r (-0.667and -0.724) for relative humidity during morning hours and relative humidity during the evening hours was found significant with negative correlation and the value of r (0.00) shows absence of linear relationship between rainfall and PDI.

Multiple regression analysis (R

Discussion

In the present investigation, an attempt was made to study the effect of various weather factors on the initiation and development of Alternaria blight. These factors included maximum temperature (X1), minimum temperature (X2), morning relative humidity (X3), evening relative humidity (X4) and rainfall (X5). The pooled data revealed that the mean disease intensity was 25.81% and 18.14% during both the seasons. The results for disease intensity of Alternaria blight showed significant variation with all-weather variations. Maximum and minimum temperature, morning and evening relative humidity and rainfall was found significant correlation with PDI. The value of r (0.637 and 0.646) for maximum and minimum temperature was found significant with positive correlation, value for r (-0.551) for relative humidity during morning hours was found significant with negative correlation and value of r (0.350) for relative humidity during the evening hours was found significant with positive correlation with PDI and value of r (0.195) for rainfall was found significant with positive correlation with PDI.

Multiple regression analysis indicated that there was 98% influence of five meteorological factors and the remaining 2% variations were unexplained during Rabi 2022-23. The value of r (0.673 and 0.569) for maximum and minimum temperature was found significant with positive correlation, value of r (-0.667and -0.724) for relative humidity during morning hours and relative humidity during the evening hours was found significant with negative correlation and the value of r (0.00) shows absence of linear relationship between rainfall and PDI. Multiple regression analysis indicated that there was 98.20% influence of five meteorological factors and the remaining 1.8% variations were unexplained during Rabi 2023-24. Kumar et al. (2002) [12] reported that Alternaria blight in cumin occurs only after flowering and is heavily influenced by cloudy and humid weather conditions, particularly during February to March. The disease develops when the maximum temperature ranges from 20 °C to 35.3 °C, the minimum temperature ranges from 3.9 °C to 10 °C, and the mean relative humidity varies between 47.5% and 73.5%, along with a peak rainfall of 18.3 mm. In a separate study, Vihol (2004) [23] observed that during the second standard week, the disease was by lower sunshine hours (6.9 hours), cloudy conditions lasting 4 to 5 days, and temperatures between 10.9 °C and 28.7 °C. The morning relative humidity ranged from 73.4% to 86.1%, which directly correlated with an increase in cumin blight intensity under field conditions. Sunder (2005) [20] found that the severity of Alternaria blight was greatest during the 11th standard meteorological week, when the morning relative humidity reached 95%, the maximum temperature was 23.6 °C, and the minimum temperature was 12.9 °C. The present study suggests that all ten selected variables should be incorporated into multiple regression models for more effective prediction of Alternaria blight in cumin, particularly in arid and semi-arid conditions. Gemawat and Prasad (1972) [7] found that sowing of cumin crop before 25th, November was suitable to reduce the disease incidence in Rajasthan. Extended date of sowing from October to December also increase the availability of continuous susceptible host in the area for longer periods (November to April) which results in spread of disease to the adjoining areas.

Champawat and Sharma (2009) [3] studied the effect of temperature, relative humidity and rainfall on Alternaria blight of tomato caused by Alternaria solani. Alternaria blight of tomato was negatively correlated with all the parameter studied. The linear regression on the appearance of blight with weather parameters also gave significantly negative regression coefficients. The multiple regression analysis revealed that parameters contribute 77 per cent towards disease incidence, the effect of maximum temperature was negatively significant. Kumar et al. (2021) [11] observed highest disease severity of leaf blight (14.80% & 15.7%) in the mid-June. High temperature (36.9 o C & 38.1 o C), and relative humidity (94% & 96.4%) were found correlated with higher severity to Alternaria leaf blight. Meena et al. (2021) [14] revealed that Alternaria blight of fennel is greatly favoured by relative humidity more than 80% and rainfall. A significant and positive correlation was recorded with morning and evening relative humidity whereas a negative non-significant correlation with maximum and minimum temperature. Fagodiya et al. (2022) [5] showed the effect of various weather factors viz., temperature, relative humidity and rainfall under inoculated conditions on Alternaria leaf spot incited by Alternaria alternata and with staggered dates of sowing were taken to observe effect on disease progression and their effect on seed yield. Meno et al. (2022) [15] showed that dispersal of A. solani and A. alternata in a potato field per hour in a day is influenced by the weather conditions that characterize the hour, but not the hour of the day. Specifically, the relative humidity and solar radiation were the most relevant weather parameters influencing the conidia concentration in the air and both in a linear model explained 98% of the variation of this concentration per hour.

References

1. Burns W. Work done under Economic Botanist for the year 1919-1920 Appendix. Journal Rep Dep Agric Bombay. 1921;126-130.
2. Chadha KL. Hand Book of Horticulture. 2006;713-714.
3. Champawat RS, Sharma RS. Influence of temperature, relative humidity and rainfall on Alternaria blight of tomato. Journal of Mycology and Plant Pathology. 2009;39(3):550-550.
4. Dange SRS. Diseases of cumin (Cuminum cyminum L.) and their management. Journal of Spices and Aromatic Crops. 1995;4:57-60.
5. Fagodiya RK, Trivedi A, Fagodia BL. Impact of weather parameters on Alternaria leaf spot of soybean incited by Alternaria alternata. Scientific Reports. 2022;12:6131-6131.
6. Gaur MM. Diseases of cumin and fennel. Plant Protection Bulletin. 1949;1(2):28-30.
7. Gemawat PD, Prasad N. Alternaria blight of Cuminum cyminum L. Physiology of pathogenesis. Proceedings of Indian National Science Academy. 1972;38:38-43.
8. Jaiman RK, Patel NR, Patel KD, Agalodiya AV, Patel PK. Management of Ramularia blight in fennel. International Journal of Seed Spices. 2013;3(1):50-51.
9. Joshi NC. Notes on two diseases of Cuminum cyminum L. from Ajmer. Science Culture. 1955;21(2):101-102.
10. Kamkar B, Koocheki A, Mahallati MN, Da Silva JAT, Moghaddam PR, Kafi M. Fungal diseases and inappropriate sowing dates: major reducing factors in International Journal of Advanced Biochemistry Research https://www.biochemjournal.com cumin fields of Iran-a case study in Khorasan provinces. Crop Protection. 2011;30(2):208-215.
11. Kumar S, Md Nadeem Akhtar, Kumar S, Kumar M, Kumar T. Influence of weather parameters on Alternaria leaf blight severity of makhana under the agro-climate of Koshi region of Bihar. Journal of Agrometeorology. 2021;23(1):54-59.
12. Kumar S, Mehra R, Srivastava MP, Panwar RP. Epidemiology of Alternaria blight of cumin. Indian Journal of Mycology and Plant Pathology. 2002;20(12):72-74.
13. Malhotra SK, Vashishtha BB. Package of practices for production of seed spices. National Research Centre on Seed Spices. Ajmer, India; 2008. p. 98.
14. Meena S, Ghasolia RP, Sharma J, Yadav SL. Effect of weather parameters on Alternaria blight of fennel incited by Alternaria alternata (Fr.) Keissler. International Journal of Chemical Studies. 2021;9(1):2639-2642.
15. Meno L, Escuredo O, Abuley IK, Seijo MC. Importance of meteorological parameters and airborne conidia to predict Alternaria risk in potato crop environments using machine learning algorithms. Sensors. 2022;22:7063-7063.
16. Nabhan GP. Cumin, Camels, and Caravans: A Spice Odyssey. University of California Press; 2014. p. 234.
17. Rai N, Yadav S, Verma AK, Tiwari L, Sharma RK. A monographic profile on quality specifications for a herbal drug and spice of commerce-Cuminum cyminum L.A. International Journal of Advanced Herbal Science and Technology. 2012;1(1):1-12.
18. Shankaracharya NB, Natrajan CP. Chemical composition and uses of cumin. Indian Food Packer. 1971;25(6):22-28.
19. M.Sc. Thesis. Anand Agricultural University, Anand (India); 2010.
20. Sunder S. Studies on cumin blight caused by Alternaria burnsii (Uppal, Patel and Kamat). M.Sc. (Agri.) Thesis. Haryana Agricultural University, Hisar (Haryana); 2005.
21. Uppal BN. India: diseases in the Bombay Presidency. International Bulletin of Plant Protection. 1933;7(5):103-104.
22. Uppal BN, Desai MK, Kamat MK. Alternaria blight of cumin. Indian Journal of Agricultural Science. 1938;7:49-62.
23. Vihol JB. Management of Alternaria blight of cumin (Cuminum cyminum L.) caused by Alternaria burnsii under North Gujarat conditions. M.Sc. (Agri.) Thesis. Sardarkrushinagar Dantiwada Agricultural University, Gujarat; 2004.