Association of vesicular arbuscular mycorrhiza with different fruit crops

Introduction

The cultivation of fruit crops has a significant impact on the overall well-being of humans and the state of the nation. A high source of important vitamins, minerals as well as high in fiber, fruits are an excellent food choice. Fruits also include a variety of antioxidants that are beneficial to one's health, such as flavonoids It is generally agreed that the per capita production and consumption of fruits can be used to determine the overall standard of living of a population. Chemical fertilizers are used to achieve an optimum plant growth and obtain good fruit yield. However, the excess use of chemical fertilizers negatively affects viable soil microorganisms, especially mycorrhizal fungi. VAM fungi are probably the most ubiquitous soil microbe that can colonize 80% of terrestrial plant species consisted of many fruit crops. Mycorrhizal colonization increased seedling survival, enhanced growth, fruit yield and quality, uniformity of fruit crops, and earlier and increased flowering as well as induced resistance to abiotic and biotic stresses. (Meena kumari et al., 2017) [8] . In marginally poor soils and under environmental stress mycorrhizal fungi can promote plant root growth. The production of high-quality fruit trees with balanced mineral nutrient is possible due to Mycorrhizal inoculation. Vesicular arbuscular mycorrhiza is the most abundant kind of mycorrhiza describe as a universal plant symbiosis. Vesicular arbuscular mycorrhizae are ubiquitous plant root symbiont considered as "keystone mutualists" in terrestrial ecosystem forming (O'Neill et al., 1995) [11] . Mycorrhiza play crucial role in natural ecosystem as well as agriculture ecosystem, hence looking forward the advantages of mycorrhizal association with different fruit crops and its correlation with soil pH, EC, soil type, percent organic matter, available nutrients etc., the study was undertaken to know the mycorrhizal species associated with different fruit crops.

Rhizosphere soil of Mango and Papaya was collected from Vihirgaon village and soil sample of Guava rhizosphere was collected from College of Agriculture, Nagpur Maharashtra. The fruit crop of Lemon, Bael, Orange and Pomegranate, the soil samples were collected from Wayagaon village and for the fruit crop Jackfruit, Aonla, Sweet orange and Banana were collected from Akola, Kargaon and Ghoturli village of Umred Taluka of Nagpur District. Sapota, Ber and Tamarind rhizospheric soil sample was collected from village Channa and Pohara of Kuhi Taluka of Nagpur District. Whereas, the rhizosphere soil from Custard apple fruit crop was collected from Regional Fruit Research Station, Taluka Katol, District Nagpur Maharashtra.

Maintenance and preservation of roots

Collected root samples from different host were thoroughly washed in tap water to remove soil particles. Selected and cleaned roots were fixed in 4% formaldehyde/acetic acid solution (Johansen, 1940) [5] .

Isolation and identification of Vesicular Arbuscular Mycorrhiza

Mycorrhized roots from different fruit crops viz., Mango, Papaya, Guava, Lemon, Bael, Orange, Pomegranate, Jackfruit, Anola, Sweet orange, Banana, Custard Apple, Sapota, Ber and Tamrind were isolated by wet sieving and decanting method (Gerdemann and Nicolson, 1963) [2] in 500µm, 104 µm and 45 µm sieve as shown in plate 1 and stained with Trypan blue (Phillips and Hayman, 1970) [12] as shown in plate 2. The spore was identified as mycorrhizal spore based on morphological characters and published literature.

Soil Analysis

The rhizosphere soil analysis was carried out by adopting standard methods as suggested by different researchers. Soil pH was determined by using an electrode pH meter following the method of Jackson (1973) [4] . Electrical conductivity (EC) of the soil, expressed in dS m⁻¹, was estimated using a conductivity meter as per Jackson (1973) [4] . Organic matter content in the soil was estimated by the titration method developed by Walkley and Black (1934) [20] . Available nitrogen (kg ha⁻¹) was determined by the alkaline potassium permanganate method following Subbiah and Asija (1956) [18] , whereas available phosphorus (kg ha⁻¹) was estimated by the Olsen method using 0.5 M NaHCO₃ at pH 8.5, followed by calorimetric measurement with a spectrophotometer as described by Olsen and Sommer (1982) [10] . Available potassium (kg ha⁻¹) was extracted with neutral normal ammonium acetate and measured using a flame photometer following Jackson (1973) [4] . Available Sulphur (mg kg⁻¹) was analysed by the turbidimetric method suggested by Chesnin and Yien (1951) [1] . For micronutrients such as available Zn, Fe, Mn, and Cu (mg kg⁻¹), the DTPA extractable method was employed and estimated using an atomic absorption spectrophotometer as recommended by Lindsay and Norvell (1978) [6] .

Results and Discussions 3.1 Isolation, identification, Percent root colonization and spore density of VAM, isolated from different fruit crops

The rhizosphere soil samples collected from different fruit crops were isolated by wet sieving and decanting method to identify the genus by studying their spores' type, colour and shape, like wise root colonization percentage and spore density were also studied as predicted in Table 2 and Plate 3. The Glomus type of spore was observed in rhizosphere soil of fruit crops in all the locations which was found singly and in cluster. Regarding colour of spore, dark orange brown colour was observed in the isolate collected from Papaya, Guava, Anola and Sweet Orange rhizosphere soil. Dark brown colour of VAM was observed in Sapota and Tamrind. Brown colour was observed in Mango, black colour spore seen at maturity in rhizosphere soil of Bael. Orange brown coloured spore observed in Lemon, Custard apple, Orange and Ber. Blackish brown colour was seen in pomegranate. Orange colour spore was observed in Banana. Spore was also found with one straight to recovered funnel shape subtending hyphae. The colour of hyphae was observed as Orange to brown. Regarding shape of mycorrhizal spore, it was globose to sub-globose in maximum isolates of fruit crops. Irregular shape was observed in Pomegranate and typical globose to sub-globose with elongated vesicles were observed in the roots of fruit crops. Based on the morphological characters of arbuscular mycorrhizal spore was identified to be Glomus sp. as given in descriptions of INVAM, 2019. The spore colour was determined according to INVAM colour chart showed spore was light yellow brown or bright yellow and transparent to translucent when young and became black brown to black at maturity. Similar result found in Manoharachary (2004) [7] , Trappe (1982) [19] , who reported the spore colour, size, shape, wall characteristics and nature of spores. Selvam and Mahadevan (2002) [14] reported wide variety of VAM species in over burden dumps and found Glomus mosse was the dominant VAM fungus. Singh and Tyagi. (1989) [17] reported the predominance of Glomus type of spores in the rhizosphere soil of both Kinnow as well as rough lemon seedlings. The maximum spore density of mycorrhiza was observed in sweet orange i.e. 39 no. of spores/100g of soil, whereas the minimum was recorded in Ber i.e., 11. The percent root colonization was maximum (34.8%) in Mango and minimum root colonizations was 15.4% in Pomegranate. Nair and Girija (1988) [9] also found that VAM colonization in roots of fruit species varied from 19.9% to 70.6%. Hasan and Khan (2004) [3] carried out a survey for mango nurseries and orchards of different age groups in Uttar Pradesh, India and reported greater colonization in nurseries (22.5-31.7%) than in orchards (11.6-27.6%). The spore population of young orchards was 190.0-314.4 and 64.0-90.9 in old orchards.

Assessment of physico-chemical properties of mycorrhizal rhizosphere soil of different fruit crops

The physico-chemical properties of mycorrhizal soil of different fruit crops collected from different location presented in Table 3. In case of soil type, all locations showed clay soil type except mycorrhizal soil collected from village Akola and Kargaon from Jackfruit and Aonla fruit crop where the soil type was loamy. Regarding pH of soil, it was in the range of 7.45±1.03 to 8.10±1.06 and in Ber collected from Channa village it was 8.10±1.06 which was maximum as compared to the other mycorrhizal samples collected from other locations. The physical property E.C (dSm -1 ) was recorded in the range of 0.083±0.03 to 0.201±0.04 and in Pomegranate it was 0.201±0.04 dSm -1 , which was maximum as compared to other location's mycorrhizal soil samples. Organic matter is known to influence arbuscular mycorrhizal fungi, the percent organic matter in all the soil sample was in the range of 1.15±0.17 to 1.50±0.21%. The maximum percent organic matter was recorded in sweet orange and minimum in Ber. The chemical properties like available nutrient of nitrogen, phosphorus, potash, Sulphur, copper, zinc, iron and magnesium were studied to know the correlation of all physical and chemical properties on mycorrhizal population Table 4 [16] reported that physicochemical properties of soil of study site were analysed i.e. soil pH ranged from 6.1 to 7.8, the EC ranged from 0.11-0.20 and the OM% ranged from 1.18 to 1.40%. Macronutrients such as N, P, K. ranged from 71.4 to 81.9, 5 to11 and187 to 262kg/acre, respectively. Micronutrient such as Cu, Zn, Fe and Mn ranged from 2.18 to 3.62, 0.76 to 1.1, 5.18 to 7.2 and 3.16 to 4.16 Kg/acre, respectively.

Correlation of physico-chemical properties with mycorrhizal spore count:

The population of vesicular arbuscular mycorrhizal spore is influenced by the physico-chemical properties of rhizosphere soil. Soil pH sensitive to AM spore helps in the stabilization of OM% in soil and VAM helps in uptake of available nutrients in soils and supply to plants. Hence effects are made to study the correlation between physicochemical properties with AM spore count of rhizosphere soil collected from fruit species of different locations as predicted in Table 4. The mycorrhizal spore counts i.e., 0.959, 0.955 and 0.953, respectively showed significant positive correlation with soil physico-chemical properties like organic matter, available macrounutrient N and K. Whereas soil pH and available micro-nutrient i.e., Cu, Fe, Mn showed negatively significant correlation i.e.,-0.836,-0.706,-0.917 and-0.913 with mycorrhiza spore count. The same results are observed by Shivakumar (2013) [16] reported Pearson correlation followed to edaphic factors such as available K on AM spore density revealed a positive correlation and negative correlation of Cu, Zn and P on AM spore population. Wani and Konde (1996) [21] reported a negative correlation between organic carbon and available phosphorous in the soil. AM spore population was positively and significantly correlated with organic carbon and available N but negatively and significantly correlated with available K, Cu and Zn in the soil. The correlation between AM spore population and available K, Fe and Mn were found to be negative and non-significant reported by Sharma and Sharma (2006) [15] .

References

1. Chesnin L, Yein CH. Turbidimetric determination of available sulfates. Soil Science Society of America Journal. 1951;15(C):149-151.
2. Gerdemann JW, Nicolson TH. Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Transactions of the British Mycological Society. 1963;46:235-246.
3. Hasan A, Khan MN. Status of arbuscular mycorrhiza in six districts of Uttar Pradesh. Mycorrhiza News. 2004;16(1):11-13.
4. Jackson ML. Soil chemical analysis. New Delhi (India): Prentice Hall India; 1973.
5. Johansen DA. Plant microtechnique. New York & London: McGraw-Hill Book Company; 1940. p. 530.
6. Lindsay WL, Norvell WA. Development of DTPA soil test for zinc, iron, manganese and copper. Soil Science Society of America Journal. 1978;42(3):421-428.
7. Manoharachary C. Biodiversity, taxonomy, ecology, conservation and biotechnology of arbuscular mycorrhizal fungi. Indian Phytopathology. 2004;57:1-6.
8. Meena Kumari, Prasad H, Kumari S, Samriti. Association of AM (arbuscular mycorrhiza) fungi in fruit crops production: a review. Pharma Innovation. 2017;6(6):204-208.
9. Nair SK, Girija VK. Incidence of vesicular-arbuscular mycorrhiza in certain tree crops of Kerala. Journal of Plantation Crops. 1988;16(1):67-68.
10. Olsen SR, Sommer LE. Phosphorus methods of soil analysis: chemical and microbiological properties. Part 2. 2nd ed. Agronomy. 1982;9(2):403-430.
11. O'Neill EG, O'Neill RV, Norby RJ. Hierarchy theory as a guide to mycorrhizal research on large scale problems. Environmental Pollution. 1995;73:271-284.
12. Phillips JM, Hayman DS. Improved procedures for clearing root and staining parasitic and vesiculararbuscular mycorrhizal fungi for rapid assessment of infection. Transactions of the British Mycological Society. 1970;55:158-161.
13. Ponpandian SV, Rose AES. Arbuscular mycorrhizal fungi associated with some agro-forestry tree species from eastern ghats of Tamil Nadu. Indian Journal of Scientific Research. 2018;20(2):6-11.
14. Selvam A, Mahadevan A. Distribution of mycorrhizas in an abandoned fly ash pond and mined sites of Neyveli Lignite Corporation, Tamil Nadu, India. Basic and Applied Ecology. 2002;3(3):277-284.
15. Sharma SD, Sharma NC. Studies on correlations between endomycorrhiza and Azotobacter population with growth, yield and soil nutrient status of apple orchards in Himachal Pradesh. Indian Journal of Horticulture. 2006;63(4):379-382.
16. Shivakumar N. Effect of edaphic factors and seasonal variation on spore density and root colonization of arbuscular mycorrhizal fungi in sugarcane fields. Annals of Microbiology. 2013;63:151-160.
17. Singh CS, Tyagi SP. Study on the occurrence of vesicular-arbuscular mycorrhizal fungi in the roots of Aeschynomene indica under the influence of various ecological factors. Zentralblatt für Mikrobiologie. 1989;144(4):241-248.
18. Subbiah BV, Asija GL. A rapid procedure for determination of available nitrogen in soil. Current Science. 1956;25:259-260.
19. Trappe JM. Synoptic key to the genera and species of zygomycetes mycorrhizal fungi. Phytopathology. 1982;72(8):1102-1108.
20. Walkley A, Black IA. An examination of the method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Science. 1934;37(1):29-38.
21. Wani PV, Konde BK. Vesicular arbuscular mycorrhizal association in garlic. Journal of Maharashtra Agricultural Universities. 1996;21(3):420-423.