COMPARISON OF MODULES OF INTEGRATED PRACTICES WITH FARMER S PRACTICES ON FARMERS FIELD TO MANAGE AFLATOXIN IN GROUNDNUT B. R. Nakrani, Assistant Research Scientist (Plant Pathology), Regional Research Station, S.D. Agricultural University, Kothara (Gujarat) Received: 08/04/2017 Edited: 17/04/2017 Accepted: 24/04/2017 Abstract: The experiment was conducted to evaluate the effectiveness of improved package against farmers practice to manage aflatoxin in Groundnut. Analysis of soil population of Aspergillus flavus and kernel infection were carried out and aflatoxin estimation was done using indirect competitive ELISA technique. The lowest soil population of A. flavus (before, 45 days after and after harvest) and seed infection by A. flavus, higher plant population, higher pod and fodder yield, less stem rot incidence and lower aflatoxin content were recorded in the improved practices as compared to the farmer s practices. Key words: Aflatoxin, Aspergillus flavus, Groundnut, Improved practices. Introduction Contamination of groundnut with aflatoxins, the secondary metabolites, produced by fungus Aspergillus flavus is a serious problem deteriorating the quality of the produce and causing health hazards (Mehan et al., 1991). Aflatoxin producing fungi, A. flavus, can infect groundnut during the crop season and even after harvest. Due to their saprophytic nature, A. flavus can inhabit the crop rhizosphere very easily and contaminate the pods with aflatoxins. Pre-harvest infection by A. flavus and consequent aflatoxin contamination is more important in the semi-arid tropics, especially when drought occurs just before harvest. Management of aflatoxin contamination requires both preventive and curative approaches throughout crop production during, harvesting, processing and storage. The adoption of improved production technologies is likely to help in improving the productivity and quality of groundnut by reducing aflatoxin contamination. In the present investigation an attempt has been made to find best integrated practices to reduce aflatoxin. Materials and Methods The on-farm trial was conducted at farmers field of Kachchh in kharif-2008-09 and at the same site in kharif-2009-10 under rainfed condition to evaluate the effectiveness of improved package against farmers practice. The trial was undertaken in two plots of 0.4 ha each, one adopting the farmers practices while the other with an improved package with following components: Summer ploughing Application of recommended dose of fertilizer Healthy seed of improved variety @ 120 kg/ha Seed treatment with carbendazim @ 2g/kg Furrow application of Trichoderma (biocontrol agent @ 2.5 kg/ha) with FYM @ 500 kg/ha Application of gypsum @ 500 kg/ha before Insects and other diseases control at proper time by recommended practices Harvest at right maturity Drying of pods properly All the observations were recorded from the 10 quadrates (each of 5 m) from both plots. Soil was sampled at three stages to monitor the levels of A. flavus population. Initial sampling was done just before, secondly 45 days after, and the final sampling at harvest in both the experimental plots. Pods from both plots were harvested at right maturity and dried under sunlight in cotton bag. Analysis of soil population of A. flavus and kernel infection were carried out as under. 179
Enumeration of A. flavus population in soil sample The collected soil samples were sieved to fine powder and mixed thoroughly. From each samples, 10 g soil sample was taken in known amount of distilled sterile water to obtain 10-3 dilution factor. From this dilution, 1 ml suspension was spread on Aspergillus Flavus and Parasiticus Agar (AFPA) medium and spread uniformly with three replications, the plates were incubated at 27 ± 2oC for five days and colonies of A. flavus were counted. The population density was calculated as colony forming units (cfu) per gram of soil. Assessment of kernel infection For seed infection, randomly collected seeds (50 seeds per sample) were imbibed in sterilized distilled water for 20-30 minutes and then surface sterilized with 0.1 % HgCl2 for 1 minute followed by three subsequent washes of sterile distilled water. The surface sterilized seeds from each sample were plated @ 10 seeds per plate containing PDA medium amended with Rose Bengal and streptomycin sulphate. The observation for seed infection was recorded after 8 days of incubation at 27 ± 2oC.The aflatoxin estimation was also done using indirect competitive ELISA technique. Results and Discussion The experiments were conducted at the farmer s field of Kachchh district during kharif-2008-09 and at the same site during kharif-2009-10 under rainfed condition to evaluate the effectiveness of improved practice against farmer s practice. The improved practice contains different inputs as mentioned in Material and Methods. The efficacy of both the practices has been judged based on various parameters viz., soil population of A. flavus (Before, 45 days after, and after harvest), seed infection, aflatoxin content, plant population, pod yield, fodder yield and stem rot disease incidence in groundnut. The data of each parameters were analyzed using two samples t test and are presented in the Table 1 for the year 2008-09, 2009-10 and pooled for both the years. 180 1. Evaluation based on soil population of A. flavus Before The data on population of A. flavus per gram of soil were recorded before of the crop during 2008-09, 2009-10 and pooled over. The data for the year 2008-09 on the population of A. flavus in the soil samples collected from both the plots were non-significant. Comparatively lower (4.03 x 103 cfu g-1soil) soil population was recorded from the plots of improved practice than farmer s practices (4.83 x 103 cfu g-1soil). Thus it indicated that there is similar population of A. flavus. In the year 2009-10, the data showed significantly lower A. flavus soil population (3.43 x 103 cfu g-1soil) as compared to farmer s practices. (9.17 x 103 cfu g-1soil) and has showed the effectiveness of improved practices. The pooled data over years revealed that there was a significant difference among both the practices in groundnut crops during Kharif 2008-09 and 2009-10. The soil population of A. flavus was found significantly lower in improved practices (3.73 x 103 cfu g-1 soil) in comparison to farmer s practices (7.00 x 103 cfug- 1soil). 45 days after The data on population of A. flavus in soil sample collected after 45 days of from both the plots showed significant difference during the year 2008-09, 2009-10 and in pooled value for both the years. The superiority of improved practices in reducing the A. flavus population was observed during both the years as well as in pooled data. During the year 2008-09, improved practices resulted significantly to lower soil population of A. flavus (3.93 x 103 cfu g-1soil) than the farmer s practices (6.67 x 103 cfu g-1soil). Same trend was observed during the year 2009-10 as significantly lower soil population of A. flavus was recorded with improved practices (2.97 x 103 cfu g-1soil) than the farmer s practices (10.80 x 103 cfu g-1soil). The data on pooled analysis showed that improved practices (3.45 x 103 cfu g-1soil) was found statistically more effective than the farmer s practices (8.73 x 103 cfu g-1soil).
After harvest The data on population of A. flavus in soil samples collected after harvest from both the practices showed highly significant differences during the year 2008-09, 2009-10 and in pooled values. During the year 2008-09, improved practices showed significantly lower soil population of A. flavus (3.17 x 103 cfu g-1soil) than the farmer s practices (9.03 x 103 cfu g-1soil). The same trend was also observed during the year 2009-10 as significantly lower soil population of A. flavus was recorded with improved practices (2.23 x 103 cfu g-1soil) than the farmer s practices (15.07 x 103 cfu g-1soil). The data on pooled analyses showed that improved practices (2.70 x 103 cfu g-1soil) was found more effective than the farmer s practices (12.05 x 103 cfu g-1soil). Overall conclusion of data on soil population of A. flavus is that there was a gradual decrease in the soil population with improved practices (from 4.03 to 2.23 x 103 cfu g-1soil); whereas a gradual increase with the farmer s practices was observed (from 4.83 to 15.07 x 103 cfu g-1soil). It indicated that adopting the improved practices year after year in the same field reduced the soil population of A. flavus. 2. Seed infection (%) The data on per cent seed infection of A. flavus in seed samples collected after harvest from both the practices showed significant differences analysis. During the year 2008-09, improved practices resulted in significantly lower seed infection (15.33 %) than the farmer s practices (34.67 %). The same trend was observed during the year 2009-10, recording significantly lower seed infection with improved practices (12.67 %) than the farmer s practices (42.33 %). The data on pooled analyses showed that improved practices (14.00 %) were found more effective than the farmer s practices (38.50 %). 3. Aflatoxin content (ppb) The data on aflatoxin content (ppb) in the undamaged seeds samples collected after harvest from both the practices showed highly significant difference during the year 2008-09, 2009-10 and in 181 pooled analysis. During the year 2008-09, improved practice (4.67 ppb) resulted in significantly lower aflatoxin content than the farmer s practices (10.12 ppb). The same trend was observed during the year 2009-10, as significantly lower aflatoxin content was recorded with the improved practices (2.73 ppb) than the farmer s practices (11.25 ppb). The data on pooled analyses showed that improved practices (3.70 ppb) were more effective in reducing the aflatoxin content in the seeds than the farmer s practices (10.68 ppb). 4. Plant population The data on plant population at harvest from both the practices showed significant difference analysis. Significantly higher plant population of 38.70, 41.70 and 40.20 with improved practices were recorded during the year 2008-09, 2009-10 and pooled over the year, respectively as compared to the farmer s practices (33.70, 32.60, and 33.20 respectively). It indicates that the seeds of improved variety with seed treatment of systemic fungicides and use of Trichoderma harzianum antagonist increased the plant survival from germination to harvest in improved practices. 5. Pod yield and Fodder yield The data on pod and fodder yield from both the practices showed highly significant difference analysis. Significantly higher pod yields (941g, 1209g, 1075g) were recorded with the improved practices during the year 2008-09, 2009-10 and pooled over the years, respectively as compared to the farmers practices (761g, 719g and 740g respectively). Same trend was also observed with the fodder yield during year 2008-09, 2009-10 and pooled data. 6. Stem rot diseases incidence (%) The incidence of stem rot was observed over the geographical areas of Kachchh during both the years. Improved practices recorded significantly less stem rot incidence 5.36 %, 5.20 % and 5.28 % during the year 2008-09, 2009-10 and pooled, respectively as compared to the farmer s practices (9.38 %, 12.27 % and 10.83 % respectively). As a spin-off experiment,
there was a reduction in stem rot incidence with improved practices as compared to the farmer s practices. The reduction in soil population of A. flavus with improved practices may be due to the beneficial effects of seed treatment with carbendazim. Carbendazim was the most effective in inhibiting the growth of A. flavus (Reddy et al., 1991; Sobti et al., 1995 and Kumar et al., 2002). The beneficial effect of soil application with the antagonistic fungus Trichoderma spp. was also effective in reducing the population of A. flavus. Trichoderma spp being a potential antagonist prevented the proliferation of A. flavus in soil. Trichoderma spp. has the ability to inhibit the growth of A. flavus in vitro by production of non volatile antibiotics (Mixon et al., 1984; Desai et al., 2000; Srilakshmi et al., 2001; Vanamala et al., 2001; Kumar et al., 2002 and Thakur et al., 2003). Application of gypsum also enhanced the control of seed colonization in plots treated with T. harzianum, reduction in aflatoxin content and improved soil health which might have resulted in improved yields (Mixon et al., 1984; Bhat et al., 1992 and Kumar et al., 2002). Harvesting the groundnut at right maturity stage decreased the seed infection of A. flavus as well as aflatoxin content in the seeds (Mehan et al., 1986; Rachaputi et al., 2002; Timmannavar et al., 2003; and Rossetto et al., 2003). Table 1: Evaluation of integrated practices with farmer s practices in groundnut (GG-2) during Kharif 2008-09 and kharif 2009-10 at farmer s field of Kachchh district Sr. No. 1 2 Seasons Practices 2008-09 2009-10 Soil population of A. flavus (x 10 3 cfu g -1 of soil) ++ Before 45 days after After harvest Seed infection (%) ++ Aflatoxin content (ppb)+++ Plant Population + Pod Yield (g)+ Fodder Yield (g)+ Stem rot disease (%) Integrated 4.03 3.93 3.17 15.33 4.67 38.70 941 1625 5.36 Farmer s 4.83 6.67 9.03 34.67 10.12 33.70 761 1278 9.38 t value 1.066 NS 2.192* 3.827** 5.535** 10.224** 3.594** 5.414** 6.141** 2.115* Integrated 3.43 2.97 2.23 12.67 2.73 41.70 1209 2135 5.20 Farmer s 9.17 10.80 15.07 42.33 11.25 32.60 719 1526 12.27 t value 3.611** 7.779** 6.439** 6.163** 11.310** 6.426* 13.529** 8.681** 3.086** Integrated 3.73 3.45 2.70 14.00 3.70 40.20 1075 1878 5.28 Farmer s 7.00 8.73 12.05 38.50 10.68 33.20 740 1402 10.83 t value 3.901** 8.292** 6.585** 9.091** 16.795** 6.428** 12.499** 9.877** 4.451** + Average of ten quadrates (each of five meters) *Significant ** Highly significant NS Non Significant ++ Average of ten quadrates with three replications +++ Average of ten quadrates with two replications 3 Pooled References Bhat, D., Shetty, H. S., Prakash, H. S. and Karanth, N. G. K. (1992). Influence of gypsum amendment to soil on Trichoderma harzianum and Aspergillus flavus in the rhizosphere of groundnut. Adv. in Pl. Sci. 5 (2): 506-510. Desai, S., Thakur, R. P., Rao, V. P. and Anjaiah, V. (2000). Characterization of isolates of Trichoderma for biocontrol potential against Aspergillus flavus infection in groundnut. Int. Arachis Newsletter 20: 57-59. Kumar, K. V. K., Desai, S., Rao, V. P., Nur, H. A., Srilakshmi, P. and Thakur, R. P. (2002). Evaluation of an integrated management package to reduce pre-harvest seed infection by Aspergillus flavus in groundnut. Int. Arachis Newsletter 22: 42 44. 182
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