B.G. Prakash and K.M. Halaswamy

332

considered, sunflower cv. KBSH-1 responded significantly to CaCl2 @ 2% concentration with the results of the observation showing maximum photosynthetic rate (27.7 µ mol CO 2 m 2 S -1), stomatal diffusive resistance (3.9 µ mol CO2 m2 S-1), total dry matter (85 g/plant at 50% flowering) and relative water content (65.1%) as compared to both the controls which was substantiated by the maximum seed yield found in that treatment. In connotation, reduced transpiration rate (1.9 µ mol CO2 m2 S-1), and higher harvest index % (35.6%) found in that treatment suggested higher efficiency in utilization of preceding soil moisture with higher flow of photosynthates from source to sink, higher capacity in drought tolerance and also higher efficiency in photosynthetic rate under drought conditions. The seed hardening process has brought out the physio-chemical changes in seed modifying physico-chemical characters by increasing the physiological activity of embryo and associated structures (Chajnowski et al. 1997 in sunflower, Mauromicale and Cavallro, 1995 in tomato).

Ultimately, the present investigation revealed that seed hardening with CaCl2 @ 2% followed by ZnSO4 @ 0.1% for six hours found to be beneficial for increasing grain yield in sunflower under dryland situations. References Chajnowski, M., Corbineau, F. and Come, D. (1997). Physiological and biochemical changes induced in sunflower seeds by osmoprinting and subsequent drying storage and aging. Seed Research, 7: 323-331. Mauromicale, G. and Cavallro, V. (1995). Effects of seed osmopriming on germination and tomato at different water potential. Seed Sci. & Technol. 23: 107-126. Sundaralingam, K., Srimathi, P. and Vanangamudi, K. (2001). Presowing seed management. In: Quality seed production. (Vanangamudi et al., eds.) p.131-138.

(Received: December 2002; Revised: May 2004)

Madras Agric. J. 91 (4-6) : 332-336 April-June 2004 Research Notes

Influence of different VAM fungi on cotton (Gossypium arboreum L.) infested with reniform nematode, Rotylenchulus reniformis N. SEENIVASAN, K. DEVRAJAN, S.B. NIRMAL JOHNSON AND G. RAJENDRAN Horticultural Research Station, Vijayanagaram, Ooty - 643 001, Tamil Nadu. Cotton (Gossypium spp.) is an important commercial crop in India, its area under production has been reduced in recent years due to various production constraints. The reniform nematode, Rotylenchulus reniformis Linford and Oliveira 1940, is considered as one of the important, production constraint which causes delayed maturity, stunting and reduction in boll size and results in the reduction of cotton yield to the extent of 40-60 percent (Balasubramanian, 1983). To

protect the crop from the nematode damage, the main dependence is the use of nematicides. Since cotton is continuously exposed to chemical pesticides to manage insect pests, nematode management through bio-control agent may reduce some sort of environmental toxicity. Among the various kinds of organisms engaged in the biological control of nematodes, vesicular Arbuscular Mycorrhizae (VAM) suppressess the root pathogenic nematodes through morphological,

Influence of different VAM fungi on cotton (Gossypium arboreum L.) infested with reniform nematode, ....

333

Table 1. Influence of different species of vesicular arbuscular mycorrhizae and Rotylenchulus reniformis on growth and yield of cotton cv. K-10

Treatments T1 T2 T3 T4 T5 T6 T7 T8 T9

- G. mosseae - G. fasciculatum - G. intravadices - G. fulvum - T1 + R. reniformis - T2 + R. reniformis - T3 + R. reniformis - T4 + R. reniformis - R. reniformis CD (P=0.05)

Shoot weight (g/plant)

Root weight (g/plant)

Shoot length (cm)

Root length (cm)

Fresh

Dry

Fresh

Dry

114.7 106.2 96.8 95.1 109.1 105.5 96.1 90.5 81.3 7.8

17.4 15.7 14.4 13.2 16.8 15.4 14.1 12.5 10.9 0.82

42.3 38.39 34.5 30.3 41.0 37.2 32.9 28.7 24.4 2.5

8.4 7.5 6.3 5.3 8.1 7.2 6.0 5.2 4.0 0.51

16.2 14.7 13.6 12.4 15.6 14.5 13.3 12.1 10.2 0.78

3.8 3.3 2.7 2.3 3.6 3.1 2.6 2.1 1.8 0.24

Cotton yield g/plant 67.9 55.5 51.2 45.3 63.7 52.0 48.4 43.5 35.5 5.6

Table 2. Influence of VAM fungi on R.reniformis, mycorrhizal colonization and spore count

Treatments

T1 T2 T3 T4 T5 T6 T7 T8 T9

- G. mosseae - G. fasciculatum - G. intravadices - G. fulvum - T1 + R. reniformis - T2 + R. reniformis - T3 + R. reniformis - T4 + R. reniformis - R. reniformis CD (P=0.05)

Nematode population in roots/plant

No. of eggs / egg mass

Nematode population/ 100 g soil

Per cent root colonization of VAM

No. of mycorrhizal spores/ 50 g soil

35.2 42.1 49.4 56.3 62.5

18.4 20.3 24.7 24.7 26.8

82.4 124.8 226.3 242.4 485.3

57.3 51.1 45.3 38.1 55.2 49.2 42.7 36.4 -

146.2 137.4 128.3 118.7 143.5 135.1 125.5 114.2 -

5.2

3.5

34.5

3.7

5.2

physiological and biochemical alterations in the host plant. Sitaramaiah and Sikora (1996) earlier reported the efficacy of VAM against R. reniformis on cotton. Many workers have also reported the interspecific and intraspecific host preference of endomycorrhizae (Dhillon, 1992). Hence, an attempt was made to select efficient species of VAM for the management of R. reniformis

in the existing cultivated cotton species Gossypium arboreum (cultivar K-10). A pot culture experiment in a completely randomized block design was conducted during the year 2001-2002 under glass house conditions in the Department of Nematology, Tamil Nadu Agricultural University, Coimbatore with ten

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N. Seenivasan, K. Devrajan, S.B. Nirmal Johnson and G. Rajendran

treatments comprising of four different VAM species viz. Glomus mosseae, G. fasciculatum, G. intraradices and G. fulvum as VAM alone and along with Rotylenchulus reniformis and R. reniformis alone. The treatments were replicated three times. VAM cultures maintained on pearl millet were used for the study. The inocula consisted of mycorrhizal spores along with the soil and root segments of the host plant. Population of R. reniformis required for the study was collected from infested fields of cotton and was maintained as pure culture on castor. The juveniles hatched out from egg mass were maintained in tap water at room temperature (28+2oC) with frequent aeration for seven days until the juveniles become pre adult. Two kg capacity clay pots were filled with pot mixture (red earth : sand : farm yard manure in the ratio of 1:2:1) and VAM cultures @ 10 g/kg soil (100 spores/g inoculum) were mixed in the soil thoroughly for each treatment. Seeds of cotton (cv K-10) surface sterilized with 0.1% mercuric chloride were sown at the rate of 5 seeds per pot and seeds germinated were thinned to 2 plants/pot on 10 days after sowing (DAS). Rotylenchulus reniformis was inoculated at the rate of 2 pre adults per g of soil at 15 DAS. The experiment was maintained up to 175 DAS and the observations on growth parameters, nematode infestation and yield were recorded. Observations on nematode infestation were recorded in terms of number of females per plant, number of eggs per egg mass and soil nematode population. Percent mycorrhizal colonization in roots was determined by staining the root bits with tryphan blue (Philips and Hayman, 1970). The spores produced by the VAM fungi were isolated and counted by wet sieving and decanting method (Gerdemann and Nicolson, 1963). The cotton yield was recorded by starting picking from 120 DAS and upto 175 DAS at 10 days interval and expressed as g per plant. The experiment was repeated at 30 days interval identical in all

respects. The data from the two experiments were pooled and analyzed statistically. The results of the study indicated that all the VAM species viz. G. mosseae, G. fasciculatum, G. intraradices and G. fulvum were found to have potential to increase the plant growth in terms of shoot length, root length, shoot weight and root weight, but VAM species varied significantly in improving the plant growth parameters. The maximum plant height was recorded in G. mosseae treated plants (114.7 cm) followed by G. fasciculatum (106.2 cm. Among the VAM treatments, G. fulvum registered the minimum plant height of 95.1 cm. Among the VAM + nematode treatments, G. mosseae recorded maximum height of 109.1 which was on par with G. mosseae alone treatment. The minimum plant height of 81.3 was recorded in R. reniformis alone treatment control. The similar trend was maintained for all the growth parameters. The maximum yield of 67.9 g/ plant was obtained in G. mosseae and it was on par with G. mosseae + R. reniformis. The next best treatment was G. fasciculatum (55.5 g/plant) and it was also on par with G. fasciculatum + R. reniformis treatment. The R. reniformis alone recorded least of 35.5 g/plant. All the VAM alone and VAM + nematode treatments were significantly superior than nematode alone. The increased growth of VAM treated plants was reported by Siquiera et al. (1986) on cotton. Growth improving potentiality of VAM species varied in our study and was in accordance with findings of Shrihari and Sreenivasa (1997) on chilli. Varied ability of VAM species for improving growth and yield may be due to differences in their ability to colonize host roots quickly and extensively. Perusal of the data on nematode population as in Table 2 showed that the population of R. reniformis in roots were significantly lower in all species of VAM treated plants than nematode

Influence of different VAM fungi on cotton (Gossypium arboreum L.) infested with reniform nematode, ....

alone treatment. The number of eggs/egg mass was also reduced by inoculation of the all the VAM species. The percent reduction in nematode population in roots and eggs/egg mass was maximum in G. mosseae with 43.6, 30.9 and 83.0 percent respectively over nematode alone. The reduction in root penetration and development of M. incognita by VAM was observed by Sikora and Schonbeck (1975) on tomato. Suppression in egg production of M.incognita on soybean inoculated with VAM was also observed by Carling et al. (1989). From the results, it was revealed that the reduction in penetration and number of eggs/egg mass in VAM treated plants ultimately reduced soil nematode population significantly. When colonization of VAM species on the host roots was considered, there existed significant variation among VAM species. VAM colonization was the maximum in G. mosseae with 57.3 percent followed by G. mosseae + R. reniformis (55.2%) that were on par and G. fulvum along with R. reniformis recorded the least percent colonization (36.4). There was similar trend in spore count as in colonization. Variation in colonization of roots by different VAM species was earlier recorded on clover (Gianinazzi - Pearson et al. 1989). Among the VAM species tested, G. mosseae inoculated plants showed greater nematode reduction, maximum VAM colonization and maximum increase in growth and yield. Hence, G. mosseae application may be a promising practice in management of reniform nematode in cotton. References Balasubramanian, P., Lakshmanan, P.L. and Sivagami Vadivelu. (1989). Plant Parasitic nematodes associated with cotton in Tamil Nadu. Presented in : National Seminar on futuristic approaches in cotton improvements, Haryana Agril. Univ., Hissar, India. pp.59.

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Carling, D.E., Roncadori, R.W. and Hussey, R.S. (1989). Interaction of vesicular arbuscular mycorrhizal fungi, root knot nematode and phosphorus fertilization on soybean. Plant Dis. 73: 730-733. Dhillon, S.S. (1992). Host endophyte specificitiy of vesicular arbuscular mycorrhizal colonization of Oryza sativa L. at the pretransplant stage in low or high phosphorous soil. Soil Biol. Biochem., 24: 405-411. Gerdemann, J.N. and Nicolson, J.H. (1963). Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Trans. Br. Mycol. Soc. 46: 235-244. Gianinazzi - Pearson, V. Banzanti, B. and Gianinazzi, S. (1989). In vitro enhancement of spore germination and early hyphal growth of vesicular arbuscular mycorrhizal fungi by host root exudates and plant favonoids. Symbiosis, 7: 243-255. Linderman, R.G. (1988). Vesicular Arbuscular mycorrhizal symbiosis. Scienntia Ani. Pl. Sci. 1: 183-188. Palanisamy, S. and Balasubramanian, P. (1983). Assessment of avoidable yield loss in cotton by fumigation with metham sodium. Nematol Medit. 11: 201-202. Phillips, J.M. and Hayman, D.S. (1970). Improved procedures for clearing roots and obtained parasite and vasicular arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Br. Mycol. Soc. 55: 156-161. Shrihari, P.C. and Sreenivasa, M.N. (1997). Response of chilli (Capsicum annum L.) to inoculation with different VAM fungi under two soil types. J. Soil Biol. Ecol., 17: 102-108. Sikora, R.A. and Schonbeck, F. (1975). Effect of vesicular arbuscular mycorrhizae on the population dynamics of the root knot nematodes. Presented in International plant protection Congress. Reports and information section V. Moscow, USSR, pp.158-166.

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Sikora, R.A. (1979). Predisposition to Meloidogyne infection by the endotropic mycorrhizal fungus Glomus mosseae. In "Root knot nematode systematics, biology and control. Eds. Lamberti, F. & Taylor, C.E.: Academic press, New York, pp.399-404. Siqueira, J.Q. Colozzi - Filhu, A., Fairia, F.H.S. and Oliverira, E. (1986). Symbiotic effectiveness of vesicular arbuscular mycorrhizal fungal species in cotton. Rev. Brasi. De. Cien. Dosolo. 10: 231-218.

Sitaramaiah, K. and Sikora, R.A. (1996). Influence of mycorrhizal fungus, Glomus fasciculatum spore concentration on Rotylenchulus reniformis population dynamics and cotton growth. Indian J. Nematol. 26: 1-6. Umesh, K.C., Krishnappa, K. and Bagyaraj, D.T. (1988). Interaction of burrowing nematode, Radopholus similis and Glomus fasciculatum in banana. Indian J. Nematol. 18: 6-11.

(Received: June 2003; Revised: May 2004)

Madras Agric. J. 91 (4-6) : 336-338 April-June 2004 Research Notes

Seasonal fluctuation of Pratylenchus coffeae and Helicotylenchus multicinctus K. DEVRAJAN, N. SEENIVASAN, G. RAJENDRAN AND S.B. NIRMAL JOHNSON Horticultural Research Station, Ooty - 643 001, Tamil Nadu. Banana ranks second next to mango in area and production occupying an area of 47.3 thousand hectares in Tamil Nadu (Shanmugavelu et al. 1992). Nearly 34 genera of nematodes are found to be associated with banana in India. The extent of yield loss was upto 62 per cent due to Pratylenchus coffeae (Rajendran et al. 1980) and 88-94 per cent due to Helicotylenchus multicinctus when occurred together with Radopholus similis (Zem and Alves, 1981) have been reported. Banana is the major crop grown in the southern districts of Tamil Nadu next to paddy and it is prone to attack by these nematode species. The temperature and rainfall play important roles in the population fluctuations of nematodes (Azmi, 1995). In the present study, an effort has been made to study the population fluctuation behaviour of Pratylenchus coffeae and Helicotylenchus multicinctus in banana. The investigation was made during the year 2000-2001 in a banana field located at

Agricultural College and Research Institute, Killikulam, Tamil Nadu. The field was infested with Pratylenchus coffeae and Helicotylenchus multicinctus. An area of 5 m2 was marked in the field and five samples were collected from five spots within this area at monthly intervals from January 1998 to December 1998. Each sample was treated as a replication. The nematodes were extracted and the population of P.coffeae and H.multicinctus were assessed for 0-5 cm, 5-10 cm, 10-15 cm and 15-20 cm depths. The data on temperature and rainfall were collected from the observatory located at the institute. The results of the population fluctuation of Pratylenchus coffeae and Helicotylenchus multicinctus are presented in Fig.1 and 2. Population of both the nematodes was high at 10-15 cm depth followed by 5-10 cm depth. at 0-5 cm depth, the population of P.coffeae and H.multicinctus varied between 0-13 and 1-21