Relationships Between Site Index and Ecological Variables of Trembling Poplar Forests (\u3ci\u3ePopulus tremula\u3c/i\u3e L.) in Türkiye

This study was carried out to identify relationships between site index (dominant height at a reference age) and ecological variables of trembling poplar forests in Türkiye. Samples were collected from 78 plots differing in elevation, aspect, inclination, slope position, and site class. Physiographic factors of the sample plots were recorded, soil samples were collected from different predefined layers from soil pits, and bedrock samples were collected for identification. From three trees at the stand top height, the tree closest to the arithmetic mean height was felled, and its height and age were determined. Physical and chemical characteristics of the soil samples were analysed. Relationships of the soil properties, physiographic factors, and climate with site index were assessed with correlation, stepwise regression, and regression tree methods. Significant relationships were found between site index at 30 years and elevation from the physiographic factors; the maximum temperature and the number of snowy days of the coldest month from the climate characteristics; fine earth, silt, and clay from the soil characteristics aggregated on pedon level. The height growth of trembling poplar was 11.8% according to stepwise regression analysis and 18% according to the regression tree method. The models obtained in the current study might help evaluate the potential of sites regarding the growth of trembling poplar

Insecticide-releasing LLDPE films as greenhouse cover materials

The use of chemical pesticides is limited by several public health concerns regarding their toxicity levels and indiscriminate use. Nevertheless, they are still vital components of agricultural industry since no other competitive equivalents to chemical pesticides still exist in terms of efficiency. This study describes the preparation and biological assessment of an insecticide releasing plasticfilm for agricultural covering purposes. The formulation was prepared by incorporation of deltamethrin loaded, nano-sized halloysite nanotubes into polymeric films. Thermal, morphological, and mechanical properties of films were characterized by Differential ScanningCalorimetry (DSC), Scanning Electron Microscopy (SEM) and Universal Testing Machine UTM. Sustained release profiles of the films were evaluated by Thermogravimetric Analysis (TGA). Results reveal that deltamethrin was successfully loaded into halloysite nanotubes and nanotube incorporation enhances the elastic modulus of linear-low density polyethylene (LLDPE)films. In addition, films exhibit sustained release function of the active agent for 60 days. Bioassays of the nanocomposite films with varying deltamethrin doses tested on grasshoppers showed that theLD50values of the films are−x1.85 105g/cm2. Insecticidal activities of films were tested in greenhouse on Medicago Sativaplants contaminated with thrips and aphid. Nanocomposites are observed to repel mature aphids and kill young aphids and thrips