Pest Management in Horticultural Ecosystems, Vol. 15, No. 1 pp 1-8 (2009) GIBBERELLIC ACID ( ) AND Pseudomonas fluorescens AS COMPONENTS OF BIOINTENSIVE PEST MANAGEMENT STRATEGY AGAINST Plutella xylostella IN CAULIFLOWER A. MOHANA SUNDARAM * and N. DHANDAPANI Depatment of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India 641 003. *E-mail : mohanasundaramiari@gmail.com ABSTRACT : Plutella xylostella is one of the most important constraints in cauliflower production. Chemical control measures are not very effective due to the development of resistance to many insecticides and hence biointensive management is desirable. Field experiments were conducted by integration of Gibberellic acid ( ) and Pseudomonas fluorescens along with various combinations of Bacillus thuringiensis var kurstaki (Btk) and P. xylostella granulosis virus (PxGV) during kharif and rabi seasons of 2004-05 at Thondamuthur and Boluvampatty villages of Coimbatore district, Tamil Nadu, India. The treatment @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk 1 kg ha -1 in alternation with PxGV @ 1.5x10 13 OB ha -1 recorded significantly lower incidence of P. xylostella and increased curd yield of cauliflower (32.33 t ha -1 and 35.33 t ha -1 ). Key words : Bacillus thuringiensis, Cauliflower, Gibberellic acid, Granulosis virus, Plutella xylostella, Pseudomonas fluorescens INTRODUCTION Plant growth regulating (PGR) substances are being increasingly used in modern agriculture for enhancing the crop yield. In India, use of PGR in vegetable cultivation is gaining importance among the farming community. Gibberellic acid (GA) and naphthalene acetic acid (NAA) were proved to be effective in increasing the yield (Muthoo et al., 1987). Studies made on the Plant Growth-Promoting Rhizobacteria (PGPR) indicated that they were able to induce the defence mechanism in host plants through alterations in the secondary plant compounds and thus enhancing the resistance in plants against challenging pathogens, nematodes and insect pests (Vidyasekaran et al., 1997; Zehuder et al., 1997; Murphy et al., 2000). Experiments had also shown that plant growth promoting substances induced by PGPR in plants, indirectly contribute to the suppression of insect population (Mukunthan, 1975; Ramamoorthy et al., 2001; Radja commare et al., 2002). In the recent years, the use of PGPR as a component of organic crop production has been receiving considerable attention. Particularly in cauliflower, synergistic effects of mineral nutrition with PGR and PGPR have been noticed for plant growth and curd yield (Vijaykumar, 2000). In our earlier studies we reported the reduction in fecundity of Spodoptera litura and Plutella xylostella developed from larvae fed with + Pseudomonas fluorescens treated leaves (Mohana Sundaram et al., 2006). All these findings clearly indicate the role of PGRs in insect pest suppression. Therefore, the present study 65
was undertaken to understand the influence of PGRs viz., Gibberellic acid and P. fluorescens along with biological control agents on the incidence of P. xylostella and curd yield parameters of cauliflower under field conditions. MATERIALS AND METHODS Field experiments were conducted during Kharif and Rabi seasons of 2004-05 at Thondamuthur and Boluvampatty villages of Coimbatore district, Tamil Nadu, India. Details of the treatments used are given in the Table 1. Each treatment was replicated three times at random on cauliflower var. Pawas following Randomized Block Design (RBD). The crop was transplanted in 20 m 2 (5m x 4m) plots at a spacing of 45cm x 45cm. Foliar applications of and P. fluorescens were carried out twice, at 15 days interval starting from 15 Days After Transplanting (DAT). On 45 th, 53 rd and 60 th DAT the microbials viz., Btk @ 1 kg ha -1 and PxGV @ 1.5 x 10 13 OB ha -1 and insecticide quinalphos @ 1200 ml ha -1 were sprayed to study the added effects. Application of Btk @ 1 kg ha -1 and PxGV @ 1.5x10 13 OB ha -1 was carried out when early instars were observed at pre-flowering stage with an interval of 7 to 10 days, using a knapsack hydraulic sprayer (Aspee Bombay) with a spray fluid volume of 250l ha -1. Tween 20 at the rate of 0.01 per cent was added as a surfactant and the spraying was carried out during evening hours. Observations on P. xylostella populations in different treatments were recorded at weekly intervals on 10 randomly selected plants in each plot. The curd yield parameters in different treatments from ten randomly selected plants per plot were also recorded at the time of harvest. RESULTS AND DISCUSSION Observations on larval population in different treatments are presented in Table 1. Larval population of P. xylostella was low (ranged from 21.00 to 22.50/10 plants) in + P. fluorescens treated plots at 45 days after transplanting. Observations on the larval population of P. xylostella on 7 th day of first spray showed that P. xylostella population was significantly low (8.00 /10 plants) in @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk @ 1 kg ha -1 in alternation with PxGV @ 1.5x10 13 OB ha -1 sprayed plots and at par with quinalphos (1.2 lit ha -1 ) (7.67 /ten plants). Since, the population increased in all treatments on 10 th day after first spray, a second spray was given. Similar trend as in first application was observed on seventh day after second spray. But ten days after second spray, P. xylostella population was low (11.33 /ten plants) in @ 100 pm + P. fluorescens @ 5 kg ha -1 + Btk @ 1 kg ha -1 followed by PxGV @ 1.5x10 13 OB ha -1 and + P. fluorescens + Btk (11.67 /ten plants) which were on par with each other. Quinalphos treated plots recorded 17.00 / ten plants compared to untreated check which recorded 48.00 /ten plants. Among the treatments, @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk 1 kg ha -1 in alternation with PxGV @ 1.5x10 13 OB ha -1 treatment recorded the maximum curd diameter (15.5cm), curd weight (1026.67g) and yield (32.33 t ha -1 ). The untreated check recorded the lowest curd diameter (8.70cm), curd weight (836.60g) and yield (20.17 t ha -1 ). Quinalphos @ 1.2 lit ha -1 treated plot registered a curd diameter, weight and yield of 11.00cm, 956.00g and 28.00 t ha -1 respectively. The other combinations viz., + P. fluorescens + Btk, + Btk in alternation with PxGV and + P. fluorescens with PxGV recorded 30.67, 30.17 and 29.67 t ha -1, respectively. The treatments of + P. fluorescens, alone and P. fluorescens alone recorded a yield of 26.67, 26.33 and 25.83 t ha -1 respectively (Table 3). Results of the second field trial are presented in Table 2. Larval population of P. xylostella was 66
relatively low (ranged from 31.00 to 32.00/ten plants) in + P. fluorescens treated plots at 45 DAT. On 7 th day of second spray P. xylostella population was significantly low (3.67 /ten plants) in @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk @ 1 kg ha -1 alternation with PxGV @ 1.5x10 13 OB ha -1 sprayed plots followed by quinalphos @ 1.2 lit ha -1 (4.00 /ten plants) and + Btk alternation with PxGV were (4.33 /ten plants) which were on par with each other. Seventh day of third spraying indicated that P. xylostella population was low (4.33 /ten plants) in + P. fluorescens + Btk alternation with PxGV and + P. fluorescens + Btk were on par with each other. But it was 7.33 /ten plants in quinalphos treated plots and 43.00 /ten plants in untreated check. Among the treatments, @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk 1 kg ha -1 in alternation with PxGV @ 1.5x10 13 OB ha -1 treatment recorded the maximum curd diameter (15.33cm), curd weight (1071.67g) and yield (35.33 t ha -1 ). The untreated check recorded the lowest curd diameter (8.00cm), curd weight (863.33g) and yield (22.50 t ha -1 ). Quinalphos @ 1.2 lit ha -1 treated plot registered a curd diameter, weight and yield of 10.67cm, 985.33g and 29.33 t ha -1 respectively. The other combinations viz., + P. fluorescens + Btk, + Btk alternation with PxGV and + P. fluorescens + PxGV recorded a yield of 33.83, 33.83 and 33.17 t ha -1, respectively. The treatments of + P. fluorescens, alone and P. fluorescens alone recorded a yield of 27.16, 26.66 and 25.00 t ha -1, respectively (Table 3). Neumann (1982) observed that in wheat grass, Agropyron smithii (Rydb.), application of, indole-3-acetic acid and kinetin reduced the fecundity and decreased the number of viable eggs of grass hopper, Aulocara elliotti (Thomus). Seed treatment and foliar application of GA 150ppm and ethrel 1000ppm on okra recorded the lowest population of aphid, (Aphis gossypii) mites, (Tetranychus telarius) and Earias vittella. (Mukunthan, 1975). Singh and Bhattacharya (2003), reported that the GA is widely used in soybean crop as plant growth regulator, which in turn resulted in reducing the population of S. litura. The foliar application of @ 100ppm at 15 and 30 DAT produced the tallest plants, largest curds and highest curd yields in cauliflower (Vijay Kumar, 2000). The application of PGPR, P. fluorescens on tomato and okra reduced the incidence and damage of leaf miner, Liriomyza trifolii, whitefly, Bemisia tabaci and also affected the fecundity of H. armigera. The P. fluorescens induced plants affected the egg laying behaviour of Helicoverpa armigera in tomato and okra (Murugan, 2003) and of P. xylostella and S. litura in cauliflower (Mohana Sundaram et al., 2006). Rao and Shylaja (2004), reported that the carrot seeds treated with P. fluorescens significantly reduced the incidence of reniform nematode, Rotylenchlulus reniformis (Linford and Oliveira) and subsequently increased the plant growth and crop yield. The application of talc formulation of P. fluorescens through seed, root, soil and foliar spray significantly reduced the leaf folder, Cnaphalocrocis medinalis incidence in rice (Radjacommare et al., 2002). Our results are in conformity with the above findings, confirming the added impact of PGR and PGPR on pest control. The action of the fungal pathogen, Beauveria bassiana and bacterial pathogen, Bacillus thuringiensis was enhanced owing to the feeding of the larvae on the P. fluorescens induced plants (Murugan 2003). Su (1987) found that combinations of PxGV + Bactospeine, ArGV + Bactospeine and ArGV + PxGV + Bactospeine were effective against both A. rapae and P. xylostella. Sairabanu (2000) reported that foliar application of PxGV alternation with Btk was found to be most effective in reducing the larval population of P. xylostella. The present study indicated that the application of @ 100 ppm + P. fluorescens @ 5 kg ha -1 + Btk 1 kg 67
Table 1. Effect of and P. fluorescens application along with microbials on P. xylostella population in cauliflower S.No. Treatments $ Number of larvae per ten plants I Spray (45 DAT) II Spray (55 DAT) 45 DAT 5 DAS 7 DAS 10DAS 5 DAS 7 DAS 10 DAS T 1 alone @ 100 ppm 23.83 21.33 20.00 20.67 21.00 24.67 28.67 (4.93) bc (4.67) I (4.53) I (4.60) g (4.64) fg (5.02) gh (5.40) hi T 2 + Btk @ 1 kg ha -1** 24.00 12.33 9.00 15.00 7.00 4.33 13.00 (4.95) bcd (3.58) bc (3.08) bcd (3.94) abc (2.74) cd (2.20) bcd (3.67) abcd T 3 + PxGV @1.5x10 13 OB ha -1** 23.83 13.00 10.67 17.33 8.00 5.00 13.67 (4.93) bc (3.67) d (3.34) ef (4.22) def (2.92) de (2.35) cde (3.76) bcde T 4 + Btk @ 1 kg ha -1** - PxGV @ 1.5x10 13 OB ha -1** 24.00 11.67 8.33 14.67 5.33 3.67 12.33 (4.95) bcd (3.49) bc (2.97) abc (3.89) abc (2.42) ab (2.04) ab (3.58) abc T 5 P. fluorescens alone @ 5 kg ha 1 26.17 23.33 23.33 24.00 23.00 26.67 30.67 (5.16) de (4.88) j (4.88) j (4.95) h (4.85) g (5.21) h (5.58) I T 6 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** 26.50 13.33 10.67 15.67 8.00 5.33 14.00 (5.20) e (3.72) de (3.34) ef (4.02) bcd (2.92) de (2.42) def (3.81) cde T 7 P. fluorescens @ 5 kg ha 1 + PxGV @ 1.5x10 13 26.00 15.33 13.00 18.00 8.00 5.33 14.33 OB ha -1** (5.15) cde (3.98) efg (3.67) g (4.30) ef (2.92) de (2.42) cdef (3.85) def T 8 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** - 26.00 14.00 9.67 15.67 7.00 4.33 13.00 PxGV @ 1.5x10 13 OB ha -1** (5.15) cde (3.81) ef (3.19) de (4.02) bcd (2.74) cd (2.20) bcd (3.67) abcd T 9 (100 ppm) + P. fluorescens @ (5kg ha -1 ) 21.00 19.00 17.33 17.67 19.33 23.33 27.33 (4.64) a (4.42) h (4.22) h (4.26) ef (4.45) f (4.88) g (5.28) h T 10 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 22.00 11.33 8.33 14.33 6.33 4.00 11.67 Btk @ 1 kg ha -1** (4.74) ab (3.44) bc (2.97) abc (3.85) ab (2.61) bc (2.12) bc (3.49) a T 11 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 22.50 12.33 9.33 16.33 6.33 4.33 12.00 PxGV @1.5x10 13 OB ha -1** (4.80) ab (3.58) cd (3.14) cde (4.10) cde (2.61) bc (2.20) bcd (3.54) ab T 12 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 22.00 11.00 8.00 13.33 5.67 3.33 11.33 Btk @ 1 kg ha -1** - PxGV @1.5x10 13 OB ha -1** (4.74) ab (3.39) ab (2.92) ab (3.72) a (2.48) ab (1.96) ab (3.44) a T 13 Btk alone @ 1 kg ha -1** 27.00 14.33 11.33 16.33 9.33 6.67 15.00 (5.24) e (3.85) ef (3.44) f (4.10) de (3.14) e (2.68) f (3.94) efg T 14 PxGV alone @1.5x10 13 OB ha -1** 26.50 16.00 14.00 19.00 9.00 6.33 16.33 (5.20) e (4.06) g (3.81) g (4.42) f (3.08) e (2.61) def (4.10) fg T 15 Quinalphos @1200 ml ha -1** 27.00 10.00 7.67 13.67 4.67 2.67 17.00 (5.24) e (3.24) a (2.86) a (3.76) a (2.27) a (1.78) ab (4.18) g T 16 Untreated check 27.50 32.00 34.67 37.67 38.33 44.33 48.00 (5.29) e (5.70) k (5.93) k (6.18) I (6.23) h (6.70) I (6.96) i In a column means followed by similar letters are not significantly different (P = 0.05) by DMRT DAT Days after transplanting # Mean of three replications $ and P. fluorescens were sprayed on 15 th and 30 th DAT ** Spray on 45 th and 55 th DAT 68
Table 2 : Effect of and P. fluorescens application along with microbials on P. xylostella population in cauliflower (Rabi season) S.No. Treatments $ Number of larvae per ten plants # I Spray (45 DAT) II Spray (53 DAT) III Spray (60 DAT) 45 DAT 5 DAS 7 DAS 10DAS 5 DAS 7 DAS 10 DAS T 1 alone @ 100 ppm 33.00 27.33 23.67 22.33 21.33 20.33 22.67 (5.79) abc (5.28) g (4.92) g (4.78) de (4.67) h (4.56) h (4.81) h T 2 + Btk @ 1 kg ha -1** 33.33 15.00 7.67 b 7.00 5.67 4.67 6.67 (5.82) bcd (3.94) bc (2.86) a (2.74) bc (2.48) cde (2.27) cde (2.68) cde T 3 + PxGV @1.5x10 13 OB ha -1** 33.00 17.00 10.00 7.33 6.00 5.00 7.00 (5.79) abc (4.18) de (3.24) cd (2.80) bc (2.55) de (2.35) def (2.74) cdef T 4 + Btk @ 1 kg ha -1** - PxGV @ 33.33 14.00 7.33 6.00 4.33 3.00 5.00 1.5x10 13 OB ha -1** (5.82) bcd (3.81) ab (2.80) a (2.55) ab (2.20) ab (1.87) ab (2.35) ab T 5 P. fluorescens alone @ 5 kg ha 1 35.00 30.00 26.00 25.00 23.67 23.00 25.00 (5.96) cde (5.52) h (5.15) g (5.05) e (4.92) I (4.85) h (5.05) h T 6 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** 35.00 16.00 8.33 7.33 6.33 5.33 7.33 (5.96) cde (4.06) cd (2.97) ab (2.80) bc (2.61) ef (2.42) ef (2.80) def T 7 P. fluorescens @ 5 kg ha 1 + PxGV @ 1.5x10 13 35.33 18.00 10.67 8.00 6.67 5.67 7.67 OB ha -1** (5.99) de (4.30) ef (3.34) de (2.92) c (2.68) ef (2.48) ef (2.86) ef T 8 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** - 35.33 15.00 7.67 6.67 5.00 4.00 6.00 PxGV @ 1.5x10 13 OB ha -1** (5.99) de (3.94) bc (2.86) ab (2.68) bc (2.35) bcd (2.12) cd (2.55) bcd T 9 (100 ppm) + P. fluorescens @ (5kg ha -1 ) 31.00 25.33 21.00 20.00 18.00 16.67 19.33 (5.61) a (5.08) g (4.64) f (4.53) d (4.30) g (4.14) g (4.45) g T 10 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 31.33 14.00 7.00 5.00 3.67 2.33 4.33 Btk @ 1 kg ha -1** (5.64) ab (3.81) ab (2.74) a (2.35) a (2.04) a (1.68) a (2.20) a T 11 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 32.00 15.00 9.00 6.00 4.67 3.67 5.67 PxGV @1.5x10 13 OB ha -1** (5.70) ab (3.94) bc (3.08) bc (2.55) ab (2.27) abc (2.04) bc (2.48) bc T 12 (100 ppm) + P. fluorescens @ 5 kg ha 1 + 31.67 13.00 7.00 5.00 3.67 2.33 4.33 Btk @ 1 kg ha -1** - PxGV @1.5x10 13 OB ha -1** (5.67) ab (3.67) ab (2.74) a (2.35) a (2.04) a (1.68) a (2.20) a T 13 Btk alone @ 1 kg ha -1** 36.00 17.00 9.00 7.00 5.67 4.67 6.67 (6.04) e (4.18) de (3.08) bc (2.74) bc (2.48) bcde (2.27) cde (2.68) cde T 14 PxGV alone @1.5x10 13 OB ha -1** 36.67 19.00 12.00 8.33 7.33 6.33 8.33 (6.10) e (4.42) f (3.54) e (2.97) c (2.80) f (2.61) f (2.97) f T Quinalphos @1200 ml ha -1** 36.33 e 14.00 8.00 6.00 4.00 3.00 7.33 15 (6.07) (3.81) ab (2.92) ab (2.55) ab (2.12) a (1.87) ab (2.80) def T 16 Untreated check 36.67 40.67 45.00 48.00 41.33 49.00 43.00 (6.10) e (6.42) I (6.75) h (6.96) f (6.47) j (7.04) I (6.60) I In a column means followed by similar letters are not significantly different (P = 0.05) by DMRT DAT Days after transplanting # Mean of three replications $ and P. fluorescens were sprayed on 15 th and 30 th DAT ** Spray on 45 th and 55 th DAT 69
Table 3 : Effect of and P. fluorescens along with the microbials application on the yield parameters of cauliflower S.No. Treatments $ 1st field trial IInd field trial Curd dia Curd weight # Yield Curd dia Curd weight Yield meter (cm) # (g) (t ha -1 ) # meter (cm) # # (g) (t ha -1 ) # T 1 alone @ 100 ppm 12.50 def 928.33 ij 26.33 fgh 13.33 abcd 968.33 hi 26.66 fg T 2 + Btk @ 1 kg ha -1** 14.17 abc 965.00 cd 29.00 bcde 14.00 abc 1005.00 cd 32.83 abc T 3 + PxGV @ 1.5x10 13 OB ha -1** 13.17 cde 953.33 defg 28.67 bcdef 14.67 abc 993.33 def 31.33 bcd T 4 + Btk @ 1 kg ha -1** - PxGV @ 1.5x10 13 OB ha -1** 14.50 abc 988.33 b 30.17 abc 13.67 abcd 1028.33 b 33.83 ab T 5 P. fluorescens alone @ 5 kg ha 1 11.50 fgh 918.33 j 25.83 gh 11.33 def 958.33 i 25.00 gh T 6 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** 12.67 def 955.00 def 28.17 bcdefg 12.00 cdef 995.00 def 30.00 cdef T 7 P. fluorescens @ 5 kg ha 1 + PxGV @ 1.5x10 13 OB ha -1** 12.17 efg 940.00 fghi 27.00 efg 12.00 cdef 980.00 fgh 30.33 cde T 8 P. fluorescens @ 5 kg ha 1 + Btk @ 1 kg ha -1** - PxGV @ 1.5x10 13 OB ha -1** 13.83 bcd 975.00 bc 28.50 bcdef 12.33 bcde 1008.33 cd 31.83 bcd T 9 (100 ppm) + P. fluorescens @ ( 5kg ha -1 ) 13.83 bcd 936.67 hi 26.67 cdefg 14.33 abc 973.33 ghi 27.16 efg T GA (100 ppm) + P. fluorescens @ 5 kg ha 1 + 10 3 Btk @ 1 kg ha -1** 15.17 ab 981.67 b 30.67 ab 15.33 a 1018.33 bc 33.83 ab T GA (100 ppm) + P. fluorescens @ 5 kg ha 1 + 11 3 PxGV @1.5x10 13 OB ha -1** 15.00 ab 961.67 cde 29.67 bcd 15.00 a 998.33 de 33.17 abc T GA (100 ppm) + P. fluorescens @ 5 kg ha 1 + Btk 12 3 @ 1 kg ha -1** - PxGV @1.5x10 13 OB ha -1** 15.50 a 1026.67 a 32.33 a 15.33 a 1071.67 a 35.33 a T 13 Btk alone @ 1 kg ha -1** 10.50 h 948.33 efgh 28.00 defg 10.00 efg 983.33 efgh 28.83 def T 14 PxGV alone @1.5x10 13 OB ha -1** 10.30 h 938.33 ghi 27.33 efgh 9.67 fg 971.67 ghi 27.16 efg T 15 Quinalphos @1200 ml ha -1** 11.00 gh 956.00 de 28.00 cdefg 10.67 ef 985.33 efg 29.33 def T 16 Untreated check 8.70 i 836.67 k 20.17 h 8.00 g 863.33 j 22.50 h In a column means followed by similar letters are not significantly different (P = 0.05) by DMRT DAT Days after transplanting # Mean of three replications $ and P. fluorescens were sprayed on 15 th and 30 th DAT ** Spray on 45 th, 53 rd and 60 th DAT 70
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