Authors:S.A. Ghaffari Nejad, G.R. Savaghebi, M. Farahbakhsh, R. Maali Amiri, and H. Rezaei
Boron (B) toxicity is an important problem in low rainfall and highly alkaline soils of central and southern part of Iran. We evaluated B toxicity tolerance of 10 Iranian wheat varieties in a greenhouse experiment. Experimental design was factorial Completely Randomized Design (CRD) with 10 wheat varieties × six B levels (0, 2.5, 5, 10, 20 and 40 mg B kg−1 soil) in three replications. The results showed a great range of tolerance among wheat varieties. Arg was the most tolerant one and Chamran showed the least tolerance. It seems that different mechanisms involved in B toxicity tolerance, namely exclusion of B from root, redistribution of B within leaves and integration of these two mechanisms. Significant negative linear correlation observed between shoot B concentration and shoot dry weight (r = 0.85, p < 0.01) and positive linear correlation between shoot B concentration and shoot dry weight reduction percentage (r = 0.82, p < 0.01).
Authors:L. Mosahaneh, H. Charehgani, M. Abdollahi, and R. Rezaei
The efficacy of single and combined application of Trichoderma harzianum and Pseudomonas fluorescens (CHA0) in the controlling of Meloidogyne javanica on tomato plants was evaluated under green house conditions. Seeds of the susceptible tomato cv. Early-Urbana were sown in clean plastic pots containing 1.5 kg steam sterilized soil. Four weeks after planting, the soil of each pot was infested with a suspension of 20 ml/kg soil of T. harzianum (106 spores/ ml) and a suspension of 15 ml/kg soil of P. fluorescens (CHA0) (108 CFU/ ml). Soil of other pots were infested with the two tested bio-agents together as a combined application. Seven days later, plants in all pots, except the controls, were inoculated with M. javanica at initial population densities of 1, 2 or 4 eggs/ cm3 soil. Sixty days after nematode inoculation, the parameters of plant growth and nematode reproduction were determined. Results showed that the nematode reproduction factor (Rf) on the plants infected with 1, 2 and 4 eggs/ cm3 decreased by 58, 63 and 31% after the single application of T. harzianum, 11, 33 and 12% after the single application of P. fluorescens (CHA0) and 43, 55 and 49% after the combined application of the bio-agents, respectively. Combined application of the two bio-agents was found to be the most effective in controlling the higher initial population density of the nematode (4 eggs/ cm3).