Analysis of growth response and tolerance index of Glycine max (L.) Merr. under hexavalent chromium stress

Background: Metal pollution has become one of the most serious environmental problems due to various human activities. It can damage or alter the biosphere reducing the agricultural productivity and can affect both animals and humans.  Emission of various pollutants into the atmosphere has many harmful effects on plant growth. Rapid urbanization, unregulated industrialization, growing transport, metal plating and agricultural activities have created a problem of heavy metals contamination. Methods: A greenhouse experiment was conducted to determine the toxicity of chromium onGlycine max. Chromium concentration applied to G. max was managed as 0.5, 2.5, 5, 10, 25, 50 and 100 mg kg-1 for experimental period of 90 days. The phytotoxic effect of chromium metal was analyzed by studying seed germination, seedling vigor index, root and shoot length, root and shoot fresh and dry weights, chlorophyll content tolerance index.Results: The data presented in this study showed that chromium metal adversely affects the seedling vigor of G. max and significantly (p<0.05) reduces seed germination and growth. The toxic effect of chromium on the seeds increased with increasing the concentration of the metal. It was also found that high concentrations of chromium (50 and 100 mg kg-1) can completely inhibit the seed germination. Conclusion: The chromium metal is extremely toxic for seeds and young seedling of G. max at high concentrations. Moreover, G. max has little potential to counteract the deleterious effect of chromium metal in soil at aforementioned treatments. The results of the present study may help in better understanding of the mechanisms involved in pytoextraction

Investigating the effect of inbound tourism on FDI: The importance of quantile estimations

The current study investigates the asymmetric effect of inbound tourism on foreign direct investment (FDI) in the world’s top tourist destinations based on monthly data for the period between 1995 and 2017. The quantile-on-quantile (QQ) approach introduced by Sim and Zhou was adopted for this study, because it assesses how various quantiles of inbound tourism affect different quantiles of FDI. Thus, the QQ approach gives a more detailed explanation of the general dependence of inbound tourism and FDI than traditional approaches, such as ordinary least squares or quantile regression. Further, the test of Granger causality in quantiles proposed by Troster et al. was also applied in this study to check the causal relationship between inbound tourism and FDI. The empirical outcomes explain that the relationship between inbound tourism and FDI is mostly positive for all countries except Mexico and Russia on low and middle quantiles, although there are significant differences throughout the nations and across all quantiles of inbound tourism and FDI

Water resources and tourism development in South Asia: an application of dynamic common correlated effect (DCCE) model

The current study explores the relationship between water resources and tourism in South Asia for the period of 1995-2017. The study employs the CIPS unit root test for stationarity of the variables and the CD test for cross-sectional dependence among cross-sectional units. As for the long-run parameters, a novel technique, known as dynamic common correlated effect (DCCE) model, is used which was recently developed by Chudik and Pesaran (J Econ 188:393-420, 2015b). The outcomes from the DCCE method suggest that water resources have a positive impact on tourism in South Asia. It is also proven that ignoring cross-sectional dependence among the cross-sectional units may bring about misleading outcomes. The findings of the study can be helpful for policymakers to understand the role of water resources in boosting tourism and contributing to the economic prosperity of South Asian countries

Comparative study of Zn-phytoextraction potential in guar (Cyamopsis tetragonoloba L.) and sesame (Sesamum indicum L.): tolerance and accumulation

Phytoextraction is a plant-based technique for removing heavy metals from polluted soil. The experiment reported in this paper was undertaken to study the Zn phytoextraction potential of Cyamopsis tetragonoloba in comparison with Sesamum indicum in the framework of a pot experiment. Plants were subjected to six Zn concentrations (0, 50, 100, 200, 300, 400 mg kg−1 soil) for 90 days to investigate Zn tolerance and accumulation. Results demonstrated that, at higher Zn levels, root, shoot lengths, biomass and chlorophyll content were all significantly reduced (p < 0.05). A steady increase in Zn accumulation with increasing concentration in soil was observed for all treatments. Both plant species had relatively high Zn tolerance and accumulation capacity, with C. tetragonoloba being more tolerant and having higher Zn accumulation than S. indicum. At 400 mg Zn kg kg−1, accumulation of Zn in C. tetragonoloba was highest in the root (439.33 mg kg−1) followed by stem (436.00 mg kg−1), leaf (40.67 mg kg−1) and pod (11.33 mg kg−1). Considering the rapid growth, high biomass, tolerance, accumulation efficiency, bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) (all greater than 1) established C. tetragonoloba as a potential candidate plant for Zn phytoextraction

Accumulation and distribution of lead (Pb) in plant tissues of guar (Cyamopsis tetragonoloba L.) and sesame (Sesamum indicum L.): profitable phytoremediation with biofuel crops

Contamination of lead indicates one of the major threats to soil system. Phytoremediation technique utilized plants which are able to tolerate and accumulate metals within in their tissues. It has recently been suggested that biofuel plants are more suitable for both utilization and remediation of metal contaminated soil. This study reported Pb phytoremediation potential of Cyamopsis tetragonoloba L. in comparison with Sesamum indicum L. in the framework of a pot-experiment. Plants were subjected to seven Pb concentrations (0, 100, 200, 400, 600, 800 and 1000 mg kg-1 soil) for 12 weeks. Our results demonstrated that both C. tetragonoloba and S. indicum were able to tolerate Pb concentrations up to 1000 mg kg-1 which confirms the plant ability to grow well in higher Pb levels. Significant metal accumulation was observed in root along with reduced biomass for both plants species. Furthermore, both plant species could possibly be used for phytostabilization, with success in marginally polluted soils where their growth would not be impaired and decontamination of Pb could be maintained at satisfying levels. However, bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) values proposed that C. tetragonoloba was more efficient for phytoremediation than S. indicum at higher Pb levels