Heavy-metal (HM) pollution is considered a leading source of environmental contamination. Heavy-metal pollution in ground water poses a serious threat to human health and the aquatic ecosystem. Conventional treatment technologies to remove the pollutants from wastewater are usually costly, time-consuming, environmentally destructive, and mostly inefficient. Phytoremediation is a cost-effective green emerging technology with long-lasting applicability. The selection of plant species is the most significant aspect for successful phytoremediation. Aquatic plants hold steep efficiency for the removal of organic and inorganic pollutants. Water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes) and Duck weed (Lemna minor) along with some other aquatic plants are prominent metal accumulator plants for the remediation of heavy-metal polluted water. The phytoremediation potential of the aquatic plant can be further enhanced by the application of innovative approaches in phytoremediation. A summarizing review regarding the use of aquatic plants in phytoremediation is gathered in order to present the broad applicability of phytoremediation.

Unexpected biomagnifications and bioaccumulation of heavy metals (HMs) in the surrounding environment has become a predicament for all living organisms together with plants. Excessive release of HMs from industrial discharge and other anthropogenic activities has threatened sustainable agricultural practices and limited the overall profitable yield of different plants species. Heavy metals at toxic levels interact with cellular molecules, leading towards the unnecessary generation of reactive oxygen species (ROS), restricting productivity and growth of the plants. The application of various osmoprotectants is a renowned approach to mitigate the harmful effects of HMs on plants. In this review, the effective role of glycine betaine (GB) in alleviation of HM stress is summarized. Glycine betaine is very important osmoregulator, and its level varies considerably among different plants. Application of GB on plants under HMs stress successfully improves growth, photosynthesis, antioxidant enzymes activities, nutrients uptake, and minimizes excessive heavy metal uptake and oxidative stress. Moreover, GB activates the adjustment of glutathione reductase (GR), ascorbic acid (AsA) and glutathione (GSH) contents in plants under HM stress. Excessive accumulation of GB through the utilization of a genetic engineering approach can successfully enhance tolerance against stress, which is considered an important feature that needs to be investigated in depth.

The major problem with the simultaneous improvement of yield with higher fiber quality is the negative association due to the linkage and pleiotropic effects between lint yield components and fiber quality parameters. The objectives of this research were to estimate the general combining ability (GCA) of parents and specific combining abilities (SCA) of hybrids for fiber quality parameters and within-boll yield components, and to determine the association of fiber quality parameters with basic within-boll lint yield components. In this study, eight cotton cultivars and 15 F 1 hybrids obtained by crossing five lines and three testers in the line × tester mating system during 2006 were planted in a randomized block design with four replications in 2007. The predominance of non-additive gene action was estimated for all traits except for the upper half mean fiber length (UHM), fiber strength, and seeds per boll, which were controlled by an additive type gene action due to the high GCA variance. Among the parents, 'Askabat-100' and 'Carmen' were the best general combiners for fiber length, strength, and uniformity index (UI). Additionally, 'GW Teks' and 'Sahin-2000' were determined to be good combiners for lint weight per seed (L/S) and spinnable fibers per seed (F/S). The SCA effects showed that the best specific combination was 'Sealand-542' × 'Sahin-2000' and 'TAM 94L-25' × 'SG-125' for lint percentage, L/S, and lint weight unit per seed surface area. The most important fiber quality parameters, UHM, fiber strength, and UI, were negatively associated with the most basic within-boll lint yield components, L/S, and F/S.

Biotic and abiotic stress factors can adversely affect the agricultural productivity leading to physiological and biochemical damage to crops. T herefore, the most effective way is to increase the resistance to stresses. Silicon plays a r o le in reducing the effects of abiotic and biotic stresses (drought, salt stress, disease and insect stress etc.) on plants. Silicon is accumulated in the cell walls and intercellular spaces and thus it has beneficial effects on disease infestations in especially small grains. T he application of silicon may reduce the effects of environmental stresses on plants while making effective use of plant nutrients such as nitrogen and phosphorous. Also, silicon may reduce the toxic effects of heavy metals in soil. I t may protect the foliage and increase light uptake and reduce respiration. T herefore, in this review, we discussed the effects of silicon on abiotic and biotic stresses in especially field crops.

Ultraviolet-B (UV-B: 280 to 320 nm) radiations have appeared to be detrimental to plants, due to their damaging effects on proteins, lipids, membranes and DNA. UV-B radiations are a significant regulator of plants’ secondary metabolites. High intensity of ultraviolet radiations may interfere with growth and productivity of crops. But low levels of UV-B radiations give rise to changes in the plants’ secondary metabolites such as phenolic compounds, carotenoids and glucoseinolates. Therefore, low intensity of UV-B radiations may be used to generate plants, enriched with secondary metabolites, having improved reproductive ability, early ripening and tolerance against fungi, bacteria and herbivores.