Factors

Selection of the best sub-contractor is a vital process in construction projects. There are many factors that must be taken into consideration when selecting sub-contractors. Improper selection of sub-contractors might lead to many problems during work progress. These include bad quality of work, and delay in project duration. This process is controlled by many factors. Forty six factors are collected from previous studies that influence sub-contractor selection. This paper identifies the most important factors that influence the selection of sub-contractors. A questionnaire was distributed to experts in the construction domain to determine the importance of factors that are taken into consideration by the main contractor to select the most suitable sub-contractor. A survey was carried out which was conducted with 29 experts in the construction field to determine the score of each factor. Statistical analysis is carried out on the feedback of the respondents of the survey. By using SPSS software, the frequency of the results of the questionnaire was determined. Examples of crosstabs between some of the most important factors are presented to provide a comparison between two factors. The mean score of each factor was determined and the p-value was calculated using the SPSS software, the significance of each factor used in the questionnaire is determined. Any factor that has a p-value less than 0.05 is considered a significant one

Mitigation Adverse Effects of Salinity Stress on Wheat Plants by Co-inoculation of Plant Growth Promoting Rhizobacteria, Arbuscular Mycorrhizal Fungi and Compost Amendment

Salinity has become one of the most important challenges in agriculture. A pot experiment was conducted during 2017/2018 and 2018/2019 seasons at the greenhouse of Fac. Agric., Cairo Univ., Giza, Egypt, on Triticum aestivum L., var. Gemmiza 10. Plants irrigated with diluted seawater with tap water (control), 4.0 6.0, 8.0 and 10.0 dS m-1 to investigate the utilization of co-inoculation of plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) and the addition of compost individually or in combination as an environmentally sustainable tools to alleviate the effects of salinity on wheat plants at both 75 days after sowing (DAS) (elongation stage) and 150 DAS (maturity stage). Salinity stress caused significant reduction in shoot height, shoot fresh and dry weights, K+/Na+ ratio and nitrogen, phosphorous and potassium contents of shoot at 75 DAS, however, Na+ concentration increased significantly. At maturity yield and its attributes, nitrogen, phosphorous and potassium contents in grain and straw decreased significantly with increasing irrigation water salinity level. Co-inoculation and/or compost amendments increased significantly the growth parameters and yield components compared to untreated plants under all irrigation water salinity levels