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Application of antagonistic agents in the rhizosphere of plants is an important approach in control of soil-borne pathogens. Establishment and persistence of biocontrol agents in the soil is a major concern in biological control. This study aimed to determine the effect of plant debris of oak forests on activity of Pseudomonas fluorescens and Trichoderma vierns against Meloidogyne javanica in tomato in green house conditions. In different treatments, both or one of the bioagents were applied to the soil inoculated with M. javanica and amended or unamended with oak plant debris. Based on the results, the growth–related factors of tomato improved in those treatments, in which plant debris were mixed with the soil. In case of nematode-related factors, the number of galls on roots decreased significantly in pots amended with plant debris. Maximum reduction in reproduction factor was observed in treatments with one or both of the biocontrol agents. In comparison to unamended treatments, the rate of reduction in root gall was 56.3% for treatments receiving T. virens and maximum increase in dry weight of root was observed in soils treated with P. fluorescens or T. virens, 68.2% and 56.1%, respectively.

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The purpose of this research is to investigate the relative importance of Avicennia marina organic matter in the feeding of Ilisha melastoma fish in the Mangrove Biosphere Reserve; It was stable isotope approach. Three primary food sources including mangrove tree leaves, microphytobenthos and suspended organic particles were analyzed isotopically. The samples of primary food sources and fish are converted into pure and simple gases such as CO, CO2 and N2 after minimizing the size and turning into powder. Then the identified isotope ratios are compared with a measured standard and the exact amount of isotope formed in the sample is obtained. In this research, sampling was done seasonally in August in the summer season and February in the winter season of 2019 in the mangrove ecosystems of Bandar Khmer, Hormozgan province.In the summer season, the average stable carbon isotope of primary food sources fluctuated from -28.07 units per thousand for mangrove leaves to -13.58 units per thousand for microphytobenthos.This average in the winter season was obtained from -28.05 units per thousand for mangrove leaves to -13.54 units per thousand for microphytobenthos.The average stable nitrogen isotope of primary food sources in the summer season fluctuated from 1.44 units per thousand for microphytobenthos to 10.72 units per thousand for suspended organic particles.The results of this research showed that in the summer season, suspended organic particles with 63% and in the winter season, microphytobenthos with 45% play the most important role in providing the food needed by the small shemsk fish.
 

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Aims: It is well known that root characteristics and soil properties can be used to predict soil detachment capacity (D_c). However, few investigations have explored the effects of root diameter and plasticity index on rill erosion process, particularly for soils under mixed modes of tree species.
Materials & Methods: To fill this gap, this study has evaluated the effects of root diameter, soil organic matter content and plasticity index on the D_c in soils under mixed modes of Crataegus ambigue, Fraxinus excelsior Linnaeus, Acer velutinum and Pterocarya fraxinifolia species, in planted forests of Gilan province (northern Iran). Moreover, these three variables were used to propose a model for predicting soil detachment capacity. For measuring D_c, the slopes (6.5, 12.3, 18.4, and 26.1%) and water discharges (0.26, 0.34, 0.44, 0.52, and 0.65 L m⁻¹ s⁻¹) were adjusted to the desired values using a laboratory flume with 3.5 and 0.2 m in length and width, respectively. These values were selected based on the field measurements of concentrated flows in the study area. Moreover, shear stress values were calculated using the hydraulic radius and the bed slope.
Findings: The results showed that when root diameter, soil organic matter and plasticity index increase, D_c decreases in soils under the studied species (p ˂ 0.01). These changes in the studied variables were confirmed by principal component analysis (PCA), which did show root diameter and plasticity index influenced the first PC (loading over 0.50) and organic matter significantly influenced PC2 (loading 0.56) (p < 0.01).
 

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