Abstract

Abstract

This research aims to identify and analyze the various factors affecting construction labor productivity covering the period from December 9, 2020, to January 31, 2021, a year after it was declared Covid-19 a pandemic. Due to the pandemic effect, the local government units in four selected study areas imposed intermittent Enhance Community Quarantine on all places to control the Coronavirus spread in compliance with the health department protocol. Fifty-five questionnaires returned out of 63 distributed are tabulated according to each group-related factor. The correlation analysis resulted in the highest coefficient value of 0.89 between the CTDEO and contractor groups. Meaning, most respondents have the same perception of the factors affecting construction's low labor productivity. Besides, results depicted that the absence of health workers on the construction site ranked 1st in the health & safety provision factor group with an RII of 0.97, followed by no safety engineers on the construction project sites with an RII of 0.93. From all the seven groups of factors, the health and safety group-related factors ranked 1st with an RII of 0.81, next, the schedule compression group with an RII of 0.78. Hypothesis testing asserted that working six days per week was one of the significant factors affecting labor productivity on the contractor's side, suggested by more than 50% of the respondents. The workforce group-related factors with an RII of 0.77 demonstrated a slight difference with the schedule compression group-related factors. Thus, the Covid-19 pandemic has a significant effect on the essential factors affecting construction's low labor productivity.

Abstract

Wheat is one of the strategic crops in most parts of the world. Mostly, the growth and yield of this plant are affected by biological and non-biological factors such as irrigation water quality, salinity, drought, high temperature. In this paper, the effects of balanced nutrition (fertilization at five levels plus control sample) in developmental stages on agrophysiological characteristics of wheat cultivars (Mehregan, Shush, Chamran 2) under drainage irrigation conditions were studied. Statistical data were collected during the cultivation period (planting, growing, harvesting). The means were compared by Duncan‘s test at 5% probability level. To examine and evaluate the presence or absence of a linear relationship between the studied variables, simple correlation coefficients of the traits were calculated with Minitab 17 software. According to the results of LSD test, the use of drainage improved grain yield, biological yield, harvest index and proline content. The evaluated indices did not show a significant difference between wheat cultivars. Pearson correlation test was performed between the studied indices and the degree of direct and inverse correlation between the indices was evaluated. In most cases, a significant correlation was observed between the evaluated indicators at the level (p less than 5%). Finally, grain yield regression analysis was performed. Based on the obtained results, the variables of biological yield, harvest index, the weight of one thousand seeds, and number of spikelets with a multiplication of effects greater than 0.962, were identified as the most effective variables on grain yield.

Abstract