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Abstract One basic method of improving rangelands in a country is the use of native as well as exotic species of plants adaptable. Among the but introduced species, Atriplex canescens has been introduced in many rangelands, but it is important and necessary to consider it’s effects on native species. In the current study the effect of chemical competition (allelopathy) of Atriplex canescens on germination of Salsola rigida has been taken into account. Salsola rigida is known as a native species of good quality traits in arid and semi-arid rangelands. In this survey 10% weight/volume (w/v) of extract from leaves and fruits of A. canescens was prepared and 25%, 50%, 75% and 100% concentrations were obtained through addition of distilled water. Distilled water was used as control treatment. Altogether five treatments of four replicates, based on a completely randomized design (CRD) were studied germination during 8 days. Different groups of treatments were categorized through Duncan’s new multiple range test. The results indicated that the available material in shoots of Atriplex canescens (fruits and leaves) exhibited allelopathic effect on germination of Salsola rigida. The highest percentage of germination was obtained from control while the lowest from the 100% treatment. In fact after exceeding of 25% concentration, germination reached its lowest percentage due to Atriplex effects.

Optimization of truss structures including topology, shape and size optimization were investigated by different researchers in the previous years. The aim of this study is discrete and continuous size optimization of two-dimensional truss structures with the fixed topology and the shape. For this purpose, the section area of the members are considered as the decision variables and the weight minimization as the objective function. The constraints are the member stresses and the node displacements which should be limited at the allowable ranges for each case. In this study, Genetic Algorithm and Particle Swarm Optimization algorithm are used for truss optimization. To analyse and determine the stresses and displacements, OpenSees software is used and linked with the codes of Genetic Algorithm and Particle Swarm Optimization algorithm provided in the MATLAB software environment. In this study, the optimization of four two-dimensional trusses including the Six-node, 10-member truss, the Eight-node, 15-member truss, the Nine-node, 17-member truss and the Twenty-node, 45-member truss under different loadings derived from the literature are done by the Genetic Algorithm and Particle Swarm Optimization algorithm and the results are compared with those of the other researchers. The comparisons show the outputs of the Genetic Algorithm are the most generally economical among the different studies for the discrete size cases while for the continuous size cases, the outputs of the Particle Swarm Optimization algorithm are the most economical.

To study the effect of potassium sulfate on seed yield, yield components and traits affecting seed yield of late maturing corn, a split split plot experiment using a randomized complete block design with three replications was carried out in Kashan Desert Research Station. Irrigation levels consisted of complete irrigation and cutting off irrigation at panicle emergence and seed filling stages which were considered as the main factor, three levels of potassium sulfate 200 (recommendation based on the soil analysis), 245 and 290 kg.ha-1 as the subplot, and two single cross of corn, KSC 700 and 704, as sub-sub plots. Effect of irrigation on traits like seed number per row, 1000 seed weight, biological yield, relative water content and relative water loss were significant. The effect of cultivar on all traits, except relative water loss, and the effect of fertilizer on all traits, except number of rows per ear, were also significant. All of the KSC700 traits, except plant highest were better than those of cultivar KSC704. The highest values for the most traits were obtained in full irrigation condition, applying potassium sulfate at the rate of 290 kg.ha-1 for KSC 700. Cutting off irrigation at the panicle emergence of KSC 900 and seed filling of KSC 704 did not cause significant reduction in seed yield. Highest correlation of grain yield were obtained with number of kernels per row, 1000 grain weight and harvest index. Stepwise regression results showed that number of rows per ear, number of kernels per row and 1000 grain weight in KSC 700, and biological yield and harvest index in KSC 704 justified 98.7 and 98.5 percent of changes, respectively.

One basic method of improving rangelands in a country is the use of native as well as exotic species of plants adaptable. Among the but introduced species, Atriplex canescens has been introduced in many rangelands, but it is important and necessary to consider it's effects on native species. In the current study the effect of chemical competition (allelopathy) of Atriplex canescens on germination of Salsola rigida has been taken into account. Salsola rigida is known as a native species of good quality traits in arid and semi-arid rangelands. In this survey 10% weight/volume (w/v) of extract from leaves and fruits of A. canescens was prepared and 25%, 50%, 75% and 100% concentrations were obtained through addition of distilled water. Distilled water was used as control treatment. Altogether five treatments of four replicates, based on a completely randomized design (CRD) were studied germination during 8 days. Different groups of treatments were categorized through Duncan's new multiple range test. The results indicated that the available material in shoots of Atriplex canescens (fruits and leaves) exhibited allelopathic effect on germination of Salsola rigida. The highest percentage of germination was obtained from control while the lowest from the 100% treatment. In fact after exceeding of 25% concentration, germination reached its lowest percentage due to Atriplex effects. [ABSTRACT FROM AUTHOR]