Status of Copper Level and Effects of Rhizatech®tm Vesicular Arbuscular Mycorrhizal Fungi on Wheat Growth, Yield and Copper Ion Uptake in Narok North Sub-county, Kenya

Abstract

Soil related abiotic factors hindering wheat production in wheat growing regions in East Africa include poor soil fertility, pests, diseases, drought and salinity. Copper (Cu) deficiency has been identified in soils in major wheat growing areas in Kenya. Majority of the farmers in the region use chemical fertilizers to alleviate this deficiency, which may be harmful to human health, animals and environment. Bio fertilizers can serve as safe natural alternative to reduce reliance on chemical fertilizers. Thus, the overall objective of this study was to determine the effect of RHIZATECH ® TM (a mixture of strains of Glomus species; including Glomus intraradices, Glomus etunicatum and Glomus mosseae) vesicular arbuscular mycorrhiza fungi, on wheat growth, grain yield and copper ion uptake under copper deficient soils in wheat growing areas in Narok North Sub-County. Fifty soil samples were collected from 50 wheat growing farms in five wards: Narok Town, Olokurto, Nkareta, Oloropil and Melili. The levels of copper in the soil samples were determined using Atomic Absorption Spectrophotometer. Greenhouse and field experiments were set up in Completely Randomized Design (CRD) and Randomized Complete Block Design (RCBD), respectively. Wheat seeds from four wheat varieties including King bird, Kenya Eagle 10, Njoro BW2 and Kenya Tai were planted in pots and furrows after treatment with or without the RHIZATECH ® TM. Roots of the germinated wheat seedlings were sampled 8 weeks after sowing to assess wheat root colonization by RHIZATECH®TM mycorrhiza. Plant height, total dry weight and grain yield were measured as response variables, 120 days after inoculation with RHIZATECH ® TM. The dry roots, shoots and grains were ground into small particles for determination of Cu ion concentration using microwave-assisted acid extraction and measured using atomic absorption spectrophotometer (AAS). Copper concentration levels varied between and within the farms of which 29 soil samples (58%) of the total 50 soil samples were below the critical value of 1.0 mg/kg and was deemed as low concentration whereas 21 soil samples (42%) of the total 50 soil samples were above the critical concentration value of 1.0 mg/kg hence were adequately supplied with copper for wheat growth. The total average mean of copper concentration in the soil samples was 0.98±0.11 (SE) mg/kg, which according to soil classification was below the critical value of copper hence, these findings are an indication of copper deficiency in soils in wheat growing areas in Narok North Sub-County. In both greenhouse and field trials, inoculation of the wheat varieties with RHIZATECH ® TM inoculant resulted in a positive impact on the wheat varieties over the non- inoculated wheat varieties (controls). In the greenhouse study, this reflected in significant mean increase at p=0.00 in RHIZATECH ® TM VAMF colonization rate from 4% to 46.5%...