Azarian Journal of Agriculture
Volume:5 Issue: 4, Aug 2018

Urbanization in developing countries has caused extensive soil and environmental contamination with heavy metals. Determination of pollution indices and fractionation of heavy metals in soil is pivotal for assessment and prediction of their mobility and hazard potentials in the environment. Therefore, in this investigation pollution factor as single (PF) and comprehensive (Pn), pollution load index (PLI) and sequential extraction technique were used for Ni, Pb, Cd, Zn, and Cu in soils affected by municipal wastewater in some large cities of Hamedan province, western Iran. According to results, PF factors for heavy metals in Hamedan, Malayer, Razan and Kabudarahang were respectively 2.47-27.40, 2.44-28.80, 2.46-27.20, and 2.50-27.10. PF results indicated that pollution intensity were 21.6-26.56 (very high) for Ni, 4.52-4.81(High) for Pb, 21.90-28.80 (very high) for Cd and 2.44-2.74 (medium) for Zn and 11.85-13.92 (very high) for Cu in the studied sites. Pn and PLI were 20.89-24.88 and 9.44-10.16 in the studied area, respectively. According to results, the OM fraction was the most abundant pool for Ni, Pb, and Cd. The mobility of metals in calcareous soils acquired for Ni (22.81%), Pb (15.32%), Cd (17.88%), and Cu (18.18%) was a representative of potential risk for groundwater contamination through deep percolation or runoff. The bioavailability factor related to each metal was estimated for Ni (26.51-35.72 %), Pb (27.67-35.55 %), Cd (30.22-39.51 %), Zn (22.06-26.71 %), and Cu (22.88-27.34 %). Such high bioavailability of heavy metals especially for Cd can severely impose adverse effects on the environment, groundwaters and accordingly human health.

The selection efficiency can be broadened for certain traits using estimates of genetic parameters, which are fundamental for plant breeding. The present study was carried out with ten maize genotypes grown in October, 2016 to April, 2017 using randomized complete block design with three replications at research field of National Maize Research Program, Rampur, Chitwan, Nepal. The objective of this study was to estimate the variability and correlation of agro-morphological traits in maize genotypes. Variation was observed for all the growth, phenology, yield and yield attributing traits among the genotypes. The genotypes, ZM-627 (4984 kg ha-1) and Across9942/Across9944 (4523 kg ha-1) were identified as promising genotypes. Grain yield had significant positive correlation for ear length, number of grains per row, number of ears per plot and thousand grains weight. Path analysis showed that ear height, days to 50% tasseling, anthesis-silking interval, ear length, ear diameter, number of grain rows per ear, number of grains per ear, number of ears per plot and 1000 grains weight had direct and positive effects on grain yield. Moderate to high estimates of GCV, PCV, heritability and genetic advance were found for plant height, ear height, thousand kernels weight, tasseling days, anthesis- silking interval and grain yield. Therefore, these traits can be used as selection indices for indirect selection for the improvement of maize productivity.

Bacterial wilt is one of the major and serious diseases of tomato and other solanaceous plants caused by Ralstonia solanacearum, one of the most important gram negative, aerobic, motile, rod-shaped, and soil borne bacteria. The disease is more prevalent in tropical, subtropical and warm temperate region of the world and the yield losses by this disease vary from 0 to 91% in the tomato. Thus, this paper intended to review the bacterial wilt control of tomato by using naturally and locally available plants and their products which have been carried out to date so as to find out gap for future research. More than 30 research and technical paper were studied and reviewed. Review focuses on plant-derived natural bactericides and their possible applications in agriculture to control tomato bacterial wilt that has been intensified as huge potential to inspire and influence modern agro-chemical research. Alcoholic leaf extract of Lantana camara, incubation of fresh organic matter of Cajanus cajan and Crotalaria juncea, rhizome extract of Cucurma longa, aqueous extracts of Adathoda vasica and Tagetes patula and essential oil of extracted from Thymol spp and Cymbopogon martini strongly inhibited the growth of bacterial pathogen Ralostonia solanacearum. This shows that phytobiocides are good alternatives to replace the chemicals in managing the bacterial wilt of tomato. The possible mechanisms of action of the plant residues are mainly considered to be antimicrobial activities followed by the indirect suppression of the pathogen through improved physical, chemical, and biological soil properties.