Assessment of Qualitative and Quantitative Characters of Two Persian Clover Ecotypes Inoculated by Rhizobium leguminosarum biovartrifoli and Pesudomonas putida Bacteria

Over the past decades, world attitude has changed towards the reduction of environmental pollutants. Harmful effects of synthetic fertilizers on environment have been identified. Bio-fertilizers are not harmful to the environment, but also they have favorable effects on plant growth processes. Soil biotechnology can be defined as the study of soil organisms and their metabolic processes which may have positive effects on plant yields. The main goal of this study is to asess the biotechnology fertilizers beneficial effects on soil organisms and their subsequently to maximize the yield. It is also our desire conside the soil quality, hygiene and environmental protection along this process. Among the strain of nitrogen-fixing bacteria, symbiotic bacteria such as rhizobium bacteria are important and essential in planning the sustainable farming systems. Several studies have shown that crop varieties which inoculated with rhizobium and pseudomonas were superior in yield production and performance.

An experiment was designed as factorial performed in randomized complete block design (RCBD) with three replications in Agricultural Research Center of Golpayegan (Isfahan) during 2010 – 2011. the purpose of this study was to evaluate the effects of inoculation of two ecotypes of Persian clover by various strains of Rhizobium leguminosarum. Biovar trifoli bacteria accompanied with plant growth promoting rhizobacteria (PGPR) Pseudomonas putida was employed to find certain qualitative and quantitative characteristics of clover yield, The main plots included two local ecotypes of Persian clover; Arak Haft Chin (V1) and Isfahan Haft Chin (V2)), the subplots included inoculation by two strain of Rhizobium; Rb-3, Rb-13 and one strain of Pseudomonas; PS -168.4 cuts were performed during the experiment and 60 kg/ha seed was used for cultivation based on local knowledge. According to recommendations of the Institute of Soil and Water the powder used for inoculum was 5 gram from every bacterium seed (Containing 108 × 5 bacteria per gram) for 100 kg seed. For better adhesion of the bacteria on the surface of seed, water with 20% sugar solution was used. (2) Sampling performed by harvesting 2 meter of every plot and 2 kg of fresh yield was transferred to oven (48 hours) with (72 °C) to determine dry matter. The crude protein content was determined by multiplying nitrogen content by the correction factor (6.25). At the end of the season a few plants from each plot were selected, and the number of nodules formed on the roots were counted and secondary roots with the highest penetration depth were measured by ruler. Analysis of variance and the means of treatments were performed using SAS software. Average interaction MSTAT- C treatments were performed using the software and the treatments were compared based on Duncan method.

The results showed that the qualitative factors have not been affected by Rhizobium and Pseudomonas bacteria so that the differences between treated plots with control were not significant. The quantitative factors except for depth of root penetration were affected by inoculation with Rhizobium and Pseudomonas bacteria and a significant difference between treated plots and control was obtained. Roberts et al. (3) reported that delay in planting caused plant growth exposure to high temperatures and long days, thus cell walls were stimulated to increase fiber and protein content and consequently digestibility was extremely reduced. The results indicated that inoculation by both bacteria (Rhizobium and Pseudomonas) has affected quantitative indicators of growth significantly and increased fresh and dry yield, plant height, leaf/stem ratio and the number of nodes on roots. However the results showed that the qualitative characteristics and root infiltration did not change significantly by inoculation of both bacteria. Plant growth promoting rhizobacteria (PGPR) leaded to an increase in the growth of quantitative traits. Inoculation with Rhizobium and Pseudomonas putida in most of the cases combined with the highest growth and treatments without inoculation (control) had the lowest growth as well. Dilip Kumar et al. (1) demonstrated that the combined inoculation of pea seeds with Rhizobium and Pseudomonas leads to an increase in plant height, root length and dry weight compared to control treatments. However the present study has shown the positive impacts of biological fertilizers on some of the growth parameters, but the important thing is the proper use of biological fertilizers. It was also concluded that the date of planting in spring is very important and delayed planting can affect forage quality.

This study showed that biofertilizers can have positive effects on growth characters of clover, and requires more research.