Effects of ZnO Nanoparticles and Biochar of Rice Straw and Cow Manure on Characteristics of Contaminated Soil and Sunflower Productivity, Oil Quality, and Heavy Metals Uptake

Abstract

Contaminated soils can cause a potential risk into the health of the environment and soil as well as the quality and productivity of plants. The objectives of our study were to investigate the integrative advantageous effects of foliar ZnO nanoparticles (NPs) (60 mg Zn NPs L−1), rice straw biochar (RSB; 8.0 t ha−1), cow-manure biochar (CMB, 8.0 t ha−1), and a combination thereof (50% of each) on sunflowers grown in agricultural land irrigated with polluted wastewater for the long term (≈50 years). The availability of heavy metals (HMs) in soil, HMs accumulation in whole biomass aboveground, growth, productivity, and quality characteristics of the sunflower were investigated. The combination treatment significantly minimized the availability of HMs in soil, and, consequently, substantially lessened the uptake of HMs by the sunflower, compared to treatments of ZnO NPs and control (i.e., untreated soil). The application of the combination treatment reduced the availability of Pb, Cr, Cu, and Cd in the soil by 78.6%, 115.3%, 153.3%, and 178.5% in comparison to untreated plots post-harvest, respectively. Compared to untreated plots, it also reduced the Pb, Cr, Cu, and Cd in plant biomass by 1.13, 5.19, 3.88, and 0.26 mg kg−1 DM, respectively. Furthermore, combination treatment followed by biochar as an individual application caused a significant improvement in sunflower productivity and quality in comparison to untreated soil. For instance, seed yield ha−1, 100-seed weight, and number of seeds per head obtained from the combination treatment was greater than the results obtained from the untreated plots by 42.6%, 47.0%, and 50.4%, respectively. In summary, the combined treatment of NPs and both RSB and CMB is recommended as a result of their positive influence on sunflower oil quality and yield as well as on minimizing the negative influences of HMs.

Nano-Fertilization as an Emerging Fertilization Technique: Why Can Modern Agriculture Benefit from Its Use?

“…Since most of these nutrients are not efficiently taken up by plants, farmers tend to use high fertilizer doses to partially remediate their low NUE values, which results in a notoriously detrimental impact on soil, water, and the overall environment [ 8 , 15 , 16 , 69 ]. The use of NFs can increase the NUE of fertilizers, enhance crop yield and quality, and decrease the negative effects of synthetic fertilizers in the context of more sustainable agriculture [ 21 , 44 , 68 ]. NFs or nano-enabled fertilizers precisely release nutrients in the root zone of plants by preventing rapid changes in the chemical composition of the nutrients in the soil, which, in turn, reduces nutrient losses.…”

“…Zinc is also involved in the regulation of auxins, protein metabolism, the biosynthesis of carbohydrates, and the protection of a plant against pathogens and environmental stresses [ 107 ]. Zinc NFs in the form of ZnO are frequently used in modern agriculture [ 21 ] since they are more efficient and cost-effective than synthetic Zn fertilizers [ 21 , 108 ] and may be used for soil mixing, seed priming [ 109 ], and foliar spray [ 21 ]. However, trace elements such as Zn can negatively affect plant growth via producing some metabolic alterations in plants if they applied in high doses [ 110 ].…”

“…Recent studies have suggested that nanotechnology may have a potential for modifying the current synthetic framework utilized in modern agriculture systems [ 19 ] by increasing the efficiency of novel agrochemicals [ 20 ] and providing solutions for environmental and agricultural problems [ 1 ]. Thus, research regarding the use of nanoparticles (NPs) has gained attention among agricultural researchers in recent years [ 5 , 20 , 21 ]. In this context, there is a scientific curiosity for the production of novel sources of fertilizers with the aim of increasing fertilizer use efficiency [ 22 ].…”

“…In this context, there is a scientific curiosity for the production of novel sources of fertilizers with the aim of increasing fertilizer use efficiency [ 22 ]. From a sustainable agriculture perspective, nanotechnology has the potential to develop new innovative types of fertilizers such as nanofertilizers (NFs) to increase global food production to feed the increasing world population [ 7 , 21 , 23 ].…”

Glycine Betaine Accumulation, Significance and Interests for Heavy Metal Tolerance in Plants

“…Plants have the capability to uptake and translocate toxic metals in different parts of their body as reported in several studies [ 21 , 22 , 23 , 24 , 25 , 26 ]. Uptake of HMs in plants not only inhibits the growth attributes of plants, but also induces toxic effects on consumer health [ 27 , 28 , 29 , 30 , 31 , 32 ].…”