ABSTRACT
A pot study was conducted to assess the significance of phosphobacterial and mycorrhizal inoculation in wheat. The results showed that phosphobacterial counts before sowing and after harvesting of wheat were significantly improved as compared to their respective control treatments. Highest phosphobacterial estimates of 86.25 x 108 g -1 soil recorded in P fertilizer treatment were statistically identical to 80.25 x 108 g -1 soil obtained with phosphobacterial inoculation. Moreover, yield and yield attributes in wheat were also affected significantly by phosphobacterial inoculation. The grain yield of 15.20 g/pot recorded with 100 kg ha -1 of applied P was statistically similar to 13.97 g /pot obtained from phosphobacterial treatment.
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DOI: 10.3923/ajps.2002.322.323
URL: https://scialert.net/abstract/?doi=ajps.2002.322.323
INTRODUCTION
Phosphate solubilizing microorganisms and mycorrhizal fungi plays a key role in the plant metabolism and crop productivity. They have been reported to increase the availability and uptake of native soil P in different crops by converting insoluble phosphates in the soil to soluble forms by producing various organic acids (Guar and Ostwal, 1972; Banik and Dey, 1982; Subba Rao, 1982; Kucey, 1987; Raced, 1994). Moreover, substantial increase in crop growth and yield by phosphobacterial and mycorrhizal inoculation has also been reported by Guar et al. (1980), Menge and Johnson (1987) and Young et al. (1988). However, the presence of phosphobacteria in sufficient quantities is always necessary in the soil for higher inoculation affectivity on the crop plants (Subba Rao, 1982).
Owing to limited informations available on the subject, therefore, a pot study was conducted to evaluate the impact of phosphobacterial and mycorrhizal inoculation with respect to yield and yield contributing attributes in wheat.
MATERIALS AND METHODS
Studies were conducted during Rabi season 1999-2000 under green house conditions at Nuclear Institute of Agriculture, Tandojam. Soil used for the purpose was silty clay in texture, low in organic matter (0.89%), Kjeldahl N (0.043%) and Olsens P (8.1 mg kg-1). Inoculum of phosphate solubilizing bacteria was prepared by using tricalcium phosphate media as modified by Subba Rao (1982). Mycorrhizal species were extracted by wet sieving and decanting method as described by Gerdemann and Nicolson (1963). The experimental treatments comprising of control (P0), 100 kg P ha-1, phosphobacteria, mycorrhiza and phosphobacteria + mycorrhiza were arranged according to Complete Randomized Design (CRD) having four replications. Each pot containing 5 kg soil was sown to seven wheat seeds. The seeds sown to phosphobacterial and mycorrhizal treatments were treated with their respective inoculum at the bacterial concentration of 5x 108 ml-1 solution. After germination, 50 ml suspension each of phosphobacteria and mycorrhiza was also imposed in addition to seed treatment for maintaining and regularizing the availability of soil P for plant growth. Soil samples obtained from each pot before sowing, but seven days after inoculation and after harvesting of wheat were assessed for phosphobacterial population using standard method.
The data recorded at maturity on yield and yield attributes were subjected to statistical analysis according to methods described by Steel and Torrie (1986). The differences among treatments means were compared by employing Duncans multiple range test (Duncan, 1970).
RESULTS AND DISCUSSION
Quantitative estimates: The microbiological analysis of the soil samples showed that before sowing of wheat, but seven days after inoculation, phosphobacterial estimates varied from 51.75 x 108 to 63.25 x 108 g-1 soil against microbial counts of 48.75 x 108 g-1 soil recorded in the control treatment (Table 1). However, phosphobacterial population in P fertilizer treatment was significantly highest showing counts of 74.75 x 108 g-1 soil. After harvesting of wheat, microbial counts of 80.25 x 108 g-1 soil recorded in phosphobacterial treatment were statistically identical to 86.25 x 108 g-1 soil obtained from the treatment receiving 100 kg ha-1 of fertilizer phosphorus. Significant variations however, were observed between phosphobacterial+ mycorrhizal treatment and single mycorrhizal inoculation by producing bacterial counts of 74.0 and 65.75 x 108 g-1 soil, respectively. Higher number of phosphobacteria recorded after harvesting of wheat may be ascribed to synergistic interactions between native rhizobacterial activities and the added phosphobacterial plus mycorrhizal species. The results are in close conformity with those reported by Barea et al. (1975) and Reid (1990).
Yield and yield parameters: The performance of phosphobacterial and mycorrhizal inoculation with regard to yield and yield attributes in wheat has been depicted in Table 2. The results showed that plant height of 59.20 cm produced by 100 kg ha-1 of fertilizer P was highest and significantly different from phosphobacteria (53.40 cm), mycorrhiza (52.80 cm) and phosphobacteria + mycorrhiza (51.90 cm). Lowest plant height of 50.90 cm however, was recorded in the control (P0) treatment. The data further revealed that number of spikelets per spike recorded were 15.8 with 100 kg P, 14.2 with phosphobacteria, 14.1 with mycorrhiza and 14.0 with phosphobacterial + mycorrhizal treatment. With the exception of pots receiving 100 kg P ha-1, the differences among rest of the treatments for number of spikelets/spike were statistically non-significant. It was also observed that by producing 46.2 number of grains per spike, phosphobacterial inoculation was statistically parallel to treatments receiving 100 kg P ha-1 (46.9 grains), mycorrhiza (45.7 grains) and phosphobacteria + mycorrhiza (45.4 grains), but significantly higher than control treatment (30.1 grains). Moreover, grain yield of 15.2 g/pot recorded with 100 kg ha-1 of fertilizer P was statistically identical to 13.97 g yielded by phosphobacterial treatment, but significantly higher than 12.34 g and 12.42 g obtained from mycorrhizal treatment and phosphobacterial + mycorrhizal inoculation, respectively.
Table 1: | Phosphobacterial estimates before sowing and after harvesting of wheat. |
Means followed by similar letters do not differ significantly from each other at 5% level of probability. |
Table 2: | Effect of phosphobacterial and mycorrhizal inoculation in wheat |
Means followed by similar letters do not differ significantly from each other at 5% level of probability. |
Significantly lowest yield of 9.09 g pot-1 however, was recorded in the control treatment (P0).
These findings have also been substantiated by many researchers, while investigating the inoculation effects of different species of phosphate solubilizing bacteria and vesicular-arbuscular fungus on variety of crop plants. Rovira (1963) recorded significant positive effect with the inoculation of Bacillus species on the yield and various yield parameters in wheat. Wanish (1990) reported that the combined inoculation of Azospirillum species and vesicular-arbuscular mycorrhiza showed better plant growth and nutrient uptake than control and single inoculation in pearl millet and summer wheat. Sharif (1999) conducted pot experiment to study the interactions among phosphate solubilizing bacteria, VAM fungus and associative N2-fixing bacteria with respect to growth and nutrient uptake in pearl millet. He reported that the plants fertilized with hardly soluble rock phosphate and inoculated with Bacillus megaterium var. phosphaticum produced significantly higher shoot dry weight as compared to plants treated only with soluble monocalcium phosphate in sterilized soil. Significant yield response of wheat to phosphobacterial and mycorrhizal inoculations warranted extensive research efforts under field conditions with a view to exploit their potential in fullest for mobilizing soil and added fertilizer phosphorus.
REFERENCES
- Banik, S. and B.K. Dey, 1982. Available phosphate content of an alluvial soil as influenced by inoculation of some isolated phosphate-solubilizing micro-organisms. Plant Soil, 69: 353-364.
CrossRefDirect Link - Gerdemann, J.W. and T.H. Nicolson, 1963. Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Trans. Br. Mycol. Soc., 46: 235-244.
CrossRefDirect Link - Kucey, R.M.N., 1987. . Increased phosphorus uptake by wheat and field beans inoculated with a phosphorus-solubilizing Penicillium bilaji strain and with vesicular-arbuscular mycorrhizal fungi. Applied Environ. Microbiol., 52: 2699-2703.
Direct Link - Rovira, A.D., 1963. Microbial inoculation of plants. Establishment of free-living N2-fixing bacteria on maize and wheat. Plant Soil, 19: 304-314.
CrossRef - Young, C.C., T.C. Juang and C.C. Chao, 1988. Effect of Rhizobium and VA mycorrhizal inoculation on nodulation, symbiotic nitrogen fixation and soybean yield in subtropical and tropical fields. Biol. Fert. Soils, 6: 165-169.
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