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Saxena, A.K.

Saxena, A.K.
Designation: 
Principal Scientist
Division/Section: 
Division of Plant Pathology
Specialisation: 
Fungal diseases of fruit crops, Post harvest disease of fruits and vegetables
Qualification: 
Ph.D.
Experience (No. of Years): 
28
Research Accomplishments: 

A. Institute Projects: Salient achievements: Symptomatology, etiology of pathogens, epidemiological studies, crop loss assessment and disease management protocols for important diseases of fruit crops were standardized. Bioefficacay of newer molecules for the disease management was evaluated Guava wilt disease: • Status of guava wilt in the guava growing tracts of northern India and guava decline in south India was ascertained. • Fusarium oxysporum f. sp psidii was established as the causal organism of the wilt whereas F. moniliforme, F. solani, Pestalosiopsis psidii, C. gloeosporioides, A. altenata were associated with the decline. • Declined guava trees had low Phosphorous, Potassium and zinc contents than their critical levels which could predisposed plants to such diseases. • A quick evaluation technique ‘Hoagland solution culture and inoculation technique’ was developed to evaluate the pathogenic potential of Fusarium isolates. (I) Epidemiological studies: GUAVA: (i) Epidemiology of following diseases have been studied to assess the impact of weather factors on the disease progression and to identify the critical factors to develop disease prediction models: Guava: fruit rot, Cercospora leaf spot, Guava canker Grapes: Downy mildew, Powdery mildew, Anthracnose: Mango: powdery mildew, anthracnose and blossom blight and leaf spot. Papaya: Powdery mildew, anthracnose Ber: powdery mildew, Isariopsis black leaf spot (ii) Disease Prediction models have been developed for the following: Grapes: (i) Downy mildew: Among the weather parameters number of rainy days had a greater influence on the disease. It followed a multi linear equation of Y = 274.33 – 1.95 x1 – 3.82 x2 – 1.86 x3 + 0.56 x4 + 3.6 x5 + 3.07 x6 – 0.08 x7 + 11.7 x8 – 5.4 x9 with R2 = 71.1%. (ii) Powdery mildew: Relative humidity at 1430 hours had the least effect whereas, the number of rainy days was the most favourable factor. It followed a multiplier regression equation of Y = 235.9 + 3.92, x1 – 3.94 x2 + 2.93 x3 – 0.25 x4 + 5.67 x5 + 4.75 x6 – 6.75 x7 + 9.97 x8-1 x9 with R2 = 93.1% (iii) Anthracnose: Most influenced by the minimum temperature followed by wind speed. The least influencing factor was relative humidity at 1330 hours. The regression equation derived was Y = 143.95 + 1.51 x1 – 9.23 x2 – 0.18 x3 + 0.77 x4 + 4.98 x5 – 6.25 x6 – 0.23 x7 + 1.5 x8 – 9.23 x9 with R2 = 61.5 %. Mango: Powdery mildew: Y= 14.99- 2.5 max temp -1.79 min temp +1.74 RH 0730 -0.86 RH 1430 +0.06 Evaporation +1.6 Wind speed -0.2 rain fall +0.22 no of rainy days +1.87 Br sun shine -1.96 VPD; R2=90.5 % Optimized model: Y= -27.87-2.67 min temp +1.8 RH 730- 0.94 RH 1430, R2=80.6 % Blossom blight: Disease was most influenced by maximum and minimum temperatures, wind speed and number of rainy days. This followed a multilinear regression equation of Y = 1353.2 – 34.46 x1 + 15.07 x2 – 11.86 x3 + 6.00 x5 – 20.86 x6 + 3.39 x7 + 15.58 x8+ .44x9; R2 = 98.6%. (c) leaf spot of mango: Disease was directly proportional to the age of the leaf and the minimum temperature followed by the Y= 60.3- 1.64 max temp -0.2 min temp +0.39 RH 0730 -0.02 RH 1430 – 2.65 Evaporation +1.12 Wind speed +0.27 rain fall -2.5 no of rainy days -1.4 Br sun shine -2.47 VPD; R2=90.0 % Optimized model: Y= 28.48-1.4 Evaporation-1.8 Br sunshine- 1.2 no of rainy days; R2=81.2 % (II) Technology for the management of field diseases: The efficacy of different fungicides, no of sprays required and the time of pre harvest application was standardized for the management of following diseases: MANGO: Powdery mildew, Anthracnose, Stem end rot, Blossom blight GRAPES: Downy mildew, Powdery mildew, Anthracnose, Greenaria fruit rot and leaf s pot: BANANA: Anthracnose GUAVA: Anthracnose, Fruit rot, Styler end rot, Fruit canker or Grey blight , Seedling blight Leaf spot. SAPOTA: Leaf spot POMEGRANATE: Leaf and Fruit spot, Antthranose BER: Powdery mildew, Black spot (III) Management of Post harvest diseases of fruit and vegetables: Protocols were developed for the safer and effective integrated management of storage rots in mango, banana and tomato. Judicious and need based application of fungicides as pre harvest treatment integrated with pot harvest treatments involving botanicals, physical methods and GRAS compounds were evaluated. Fungicides were not used as post harvest treatments in developing safer and effective protocols Four pre harvest applications at fifteen days interval were applied to the crop in the field at peanut stage of fruits in mango; early greenish stage of fruits in banana and flower bud opening stage in tomato. Harvesting of the fruits was done at the maturity levels avoiding any injury or physical damage to the fruits. Mango: (i) post harvest usage of Neem leaf extract (5%) or Vitex negundo leaf extract (5%) or Azoxystrobin (0.1%) preceded by pre harvest application of Prochloraz (0.1%) or Azoxystrobin (0.1%) and (ii) post harvest usage of Garlic extract (5%) or Turmeric extract (5%) preceded by pre harvest application of Vitex negundo leaves extract (5%) were most effective for the management of fruit rots in mango. (ii) Treating mango fruits in Hot water for 10 min at 52oC preceded by pre harvest application of Prochloraz (0.1%) or Thiophanate methyl (0.1%0 or Carbendazim (0.1%) was most effective that resulted in complete control of anthracnose and Aspergillus rot in var. Totapuri and recorded minimal fruits (3.33%) having stem rot. The fungicide residues in such fruits were much below the MRL values. Banana: Integration of pre harvest application of Carbendazim (0.1%) or Prochloraz (0.1%) with the post harvest application of botanicals namely Garlic extract (5%) or Turmeric extract (5%) and Neem leaf extract (5%) and GRAS compounds namely Potassium metabisulphite (2%) or Sorbic acid (1%) resulted in complete control of fruit rot. Tomato: Pre harvest application of Zineb (0.2%) or Chlorothalonil (0.2%) integrated with the post harvest treatment with Turmeric extract / Neem leaf extract were most effective that recorded more than 90% healthy fruits. (B) ICAR-Network projects: Project I: Wilts of crops with special reference to cultural, morphological, molecular characterization and pathogenic variability of Fusarium isolates in India 1.Total no of eighty (80) isolates of FOC isolated from the wilt infected rhizome samples collected from the different localities were purified and studied for the variability among them. Large variability was observed among the FOC isolates. Colonies of FOC isolates differed considerably with regard to mycelial growth as slow, moderate and fast; dimensions of macro conidia of all isolates were recorded and grouped as small (17-20 µm) and large (20-26 µm); isolates exhibited either profuse or sparse pattern of growth, whereas mycelial pigmentation varied from white, pinkish white to bluish white. Considering all these characters all the FOC isolates were categorized in 23 groups. 2. Inhibitory potential of 10 selected isolates of Trichoderma harzianum was assessed by dual culture method in vitro. T. harzianum isolate HSG-12B could inhibit the mycelial growth of of FOC by 60.07% followed by T. harzianum isolate HSG-11B which inhibited the mycelial growth by 58.15%. The T. harzianum isolate HSG-16B recorded the least suppression of mycelial growth (32.95%) 3. Inhibitory potential of selected botanicals namely Neem leaves extract, Garlic extract and Vitex negundo leaves extract was evaluated in vitro. Among the different concentration of extracts evaluated, extract at 5% was most inhibitory. Vitex negundo leaves extract (5%) resulted in more inhibition of FOC than Garlic extract (5%) and Neem leaves extract (5%). It resulted in 25.00% and 90.30% inhibition in conidial germination and mycelial growth, respectively whereas Garlic extract (5%) and Neem Leaf Extract (5%) caused 18.50% & 72.41% and 17.00% and 66.00% inhibition in conidial germination and mycelial growth, respectively. Project II: Molecular breeding in banana - development of molecular markers linked Fusarium wilt resistance: (a) Screening of Banana germ plasm against wilt disease caused by Fusarium oxysporum cubense Banana varieties namely Ney Poovan, Yellaki bale, 13 – 10 – 1, Kapooravalli, Amthur kela, Tongat, cultivar Rose, Sanna chan kadali and Pisang lilin gave susceptible reaction as per the field observations on rhizome and isolation of FOC from the infected tissue. The wild types like, M. acuminata ssp banksii, M. accuminata (wild), M. accuminata (cal-4) M. accuminata malaccensis, M. schizocarpa and cultivars Dwarf Cavendish, Vala kunnan, Mysoreni Hill, Cuba, Jurmorey, Bungan, Klue fi parad ,Matti, Kadali, Pisang jari buya, Annara kunan and Anaikomban did not show any rhizome infection nor FOC could be isolated from their rhizome. M. acuminata x Kadali and M. acuminata x Hoo bale were also disease free. (c) Non-destructive in vitro evaluation of Banana accessions: Non destructive procedure (Companion et al., 2003) was followed to evaluate the banana accessions (including hybrids) for the reaction to the culture filtrate obtained from FOC (Fusarium oxysporum cubenuse race-1). There were variations in the size of lesion area developed on inoculation of culture filtrate to the leaves of different banana accessions (susceptible, resistant and hybrids).In banana accessions (resistant to FOC race 1) namely Pisang lilin, Annara Kunnan and Calcutta-4 mean lesion area (mm2) were 0.92, 1.24 and 1.48, respectively compared with susceptible control (Ney poovan), which recorded 2.19 mm2. Similarly the differences in mean lesion area (mm2) compared with control were 1.29, 0.95 and 0.71, respectively.The lesion area (mm2) in different hybrids varied from 1.03 (F1Fu 33) to 2.18 (F1Fu 60) with corresponding mean difference in lesion area (mm2) of 1.16 to 0.01 compared with susceptible control. F1Fu 33 and F1Fu 54 recorded higher mean differences (1.16 and 1.01), compared with F1Fu 47 (0.98), F1Fu51 (0.85), F1Fu 43 (0.75), F1Fu 52 (0.73), F1Fu 42 & F1Fu 48 (0.65), F1Fu 39 (0.46), whereas in hybrids namely F1Fu 60 (0.01), F1Fu 34 (0.06), F1Fu 70 (0.09) and F1 Fu 50 (0.11) mean differences were low. Project III: Development of transgenic banana cv Rasthali resistant to Fusarium wilt: (i) Screening of Transformed banana plants against wilt disease caused by Fusarium oxysporum cubense (FOC): (a) Non-destructive in vitro evaluation of transformed Banana plants:Non destructive procedure (Companion et al., 2003) was followed to evaluate the transformed banana plants Leaves and from the polyhouse grown banana cv. Rasthali (Plant 6 - susceptible to FOC race-1), Pisang lily (Plant 8 - resistant to FOC race-1) and transformed Rasthali banana plants (1,2,3,4,5 and 7) were evaluated for their reaction to the culture filtrate obtained from FOC (Fusarium oxysporum cubense race-1). In transformed Rasthali banana plants namely, Plant 1, Plant 2, Plant 7 and Plant 8 (resistant) mean lesion area (mm2) was 1.44 ± 0.768, 1.00 ± 0.000, 0.98 ± 0.035 and1.11 ± 0.191, with corresponding differences in mean lesion area (mm2) compared with control were 9.00 ± 5.786, 9.44 ± 5.484, 9.46 ± 5.473 and 9.33 ± 5.610, respectively, whereas in Plant 3, Plant 4 and Plant 5 mean lesion area (mm2) was 3.54 ± 2.069, 1.61 ± 0.672 and 1.89 ± 0.255 respectively, with corresponding differences in mean lesion area (mm2) compared with control was 6.90 ± 6.91, 8.83 ± 5.498 and 8.55 ± 5.644, respectively. In control (Plant 6 - susceptible Rasthali) mean lesion area was 10.44 ± 5.484 mm2 whereas Plant 8 (known resistant - Pisang lily) recorded1.11 ± 0.191 mm2 mean lesion area. (b) Evaluation of transformed banana plants under challenge inoculated conditions: Pot Screening of transformed banana plants: Fifteen transformed (transgenic) banana plants were screened against Fusarium wilt in cement pots. There were variations in the expression of the foliar symptoms in the transgenic banana plants. Three plants namely Plant 1, Plant 2 and Plant 6 scored the PDI = 20% and survived. In rest of the plants (Plant 3, Plant 4, Plant 5, Plant 7, Plant 8, Plant 9, Plant 10, Plant 11 and Plant 12) PDI was 100% and these plants died whereas in Plant 13 the score was 60%. Non transgenic susceptible plants (Plant 11 - Plant 15) scored between 60 – 100% followed by total plant death except in Plant 14 the score was 20%

Important Publications: 

1. Sukhada Mohandas, R.Manjula, A. K. Saxena, K. M. Ajay, B. Shakunthala, H. D. Sowmya and S. Meenakshi (2011). Transformation of banana cv Nanjangud Rasbale (Rasthali, Silk group AAB) with AMP gene and application of bioassay for screening for Fusarium resistance. Acta Hort. 897: 293-295. 2. A. K. Saxena (2010). Post-harvest diseases of fruits in transit and storage in India and their control. In Microbial Diversity and Plant Disease Management (Edit: Dr. K. P. Singh. and D. K. Shahi), VDM Verlag Dr. Muller, Germany 538-562 pp. 3. Gajanana, T.M., Sudha, M., Saxena, A. K. and Dakshinamoorthy, V. (2010). Post harvest handling, marketing and assessment of losses in papaya. Acta Hort. 851:519-526. 4. Rawal, R. D., Venugopalan, R. and Saxena, A. K. (2008). A statistical model for describing the epidemiology of incidence of downy mildew in grapes. Acta Hort. 785: 279-284. 5. Rawal, R. D., Venugopalan, R. and Saxena, A. K. (2008). A statistical model for predicting the outbreak of powdery mildew in grapes. Acta Hort. 785: 293-296. 6. Venugopalan, R, Rawal, R.D., and Saxena, A. K. (2006).A statistical model for ascertaining the influence and reliability of weather parameters on incidence of blossom blight in Mango (Mangifera indica) J. Hort. Science. 1 (1): 64 -67. 7. A. K. Saxena and Sharma, S.R. (1989). Effect of some stionic combinations and host nutrition on viral/mycoplasmal disease of citrus J. Turk. Phytopath. (18): 17-29. 8. Saxena, A. K. and R. D. Rawal (1989) Wilt of mango - a new disease. Plant Disease Research 4 (1): 90.

Contact Details
Address for Communication: 
No.28, “SHREEKALPATARU", 1st Floor South, 1st Main, 1st A Cross, Chikkabommasandra, GKVK Post, Yelanka New Town, Bangalore - 560 065.
Email Address: 
aks@iihr.res.in, arvindkumarsaxena@gmail.com
Telephone #: 
9448535950 080- 28566763
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