The Applications of Nanotechnology in Crop Production

With the frequent occurrence of extreme climate, global agriculture is confronted with unprecedented challenges, including increased food demand and a decline in crop production. Nanotechnology is a promising way to boost crop production, enhance crop tolerance and decrease the environmental pollution. In this review, we summarize the recent findings regarding innovative nanotechnology in crop production, which could help us respond to agricultural challenges. Nanotechnology, which involves the use of nanomaterials as carriers, has a number of diverse applications in plant growth and crop production, including in nanofertilizers, nanopesticides, nanosensors and nanobiotechnology. The unique structures of nanomaterials such as high specific surface area, centralized distribution size and excellent biocompatibility facilitate the efficacy and stability of agro-chemicals. Besides, using appropriate nanomaterials in plant growth stages or stress conditions effectively promote plant growth and increase tolerance to stresses. Moreover, emerging nanotools and nanobiotechnology provide a new platform to monitor and modify crops at the molecular level.

Silicon Improves the Redox Homeostasis to Alleviate Glyphosate Toxicity in Tomato Plants—Are Nanomaterials Relevant?

Given the widespread use of glyphosate (GLY), this agrochemical is becoming a source of contamination in agricultural soils, affecting non-target plants. Therefore, sustainable strategies to increase crop tolerance to GLY are needed. From this perspective and recalling silicon (Si)’s role in alleviating different abiotic stresses, the main goal of this study was to assess if the foliar application of Si, either as bulk or nano forms, is capable of enhancing Solanum lycopersicum L. tolerance to GLY (10 mg kg−1). After 28 d, GLY-treated plants exhibited growth-related disorders in both shoots and roots, accompanied by an overproduction of superoxide anion (O2•−) and malondialdehyde (MDA) in shoots. Although plants solely exposed to GLY have activated non-enzymatic antioxidant mechanisms (proline, ascorbate and glutathione), a generalized inhibition of the antioxidant enzymes was found, suggesting the occurrence of great redox disturbances. In response to Si or nano-SiO2 co-application, most of GLY phytotoxic effects on growth were prevented, accompanied with a better ROS removal, especially by an upregulation of the main antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Overall, results pointed towards the potential of both sources of Si to reduce GLY-induced oxidative stress, without major differences between their efficacy.

​Promoting Rhizosphere Microorganisms and Biopesticides: A Review

Microbes are associated inside and outside tissue parts of producers like plants, lichen, algae and phototrophic bacteria. Biofertilizer bacteria, fungi, algae and protozoa provide the suitable environment condition, nutrition constituents and inhibit harmful microorganism from rhizosphere zone. Biofertilizer and biocontrol microbes play key roles for improved soil texture, secreting, hormones, antibiotics and various stress signal compounds, enhancement plant parts elongation and prevent pathogen microbial population. Plant growth promotion rhizosphere microorganisms can improve crop tolerance for the non- living stresses such as drought, heat and salinity and living stress such as soil borne pathogens, over load of the microbial population liable to turn out to be more incessant as various atmosphere design keep on creating. Plant disease major issue for loss of productivity and unsafe for living organism due to chemical pesticides, insecticides, fungicides, bactericides and chemical fertilizer. Due to its high potential as an alternative/complement to these pesticides, biological disease control is now generally recognized and constitutes a low cost-efficient eco-friendly biofertilizer, biocontrol, biopesticide and bioinsecticide.

Sweetpotato Response to Reduced Rates of Dicamba

A field study was conducted in Mississippi to determine the effect of reduced dicamba rates on sweetpotato crop tolerance and storage root yield, simulating off-target movement or sprayer tank contamination. Treatments were a non-treated control and four rates of dicamba [70 g ae ha−1 (1/8X), 35 g ae ha−1 (1/16X), 8.65 g ae ha−1 (1/64X) and 1.09 g ae ha−1 (1/512X)] applied either 3 days before transplanting (DBP) or 1, 3, 5, or 7 weeks after transplanting (WAP). An additional treatment consisted of 560 g ae ha−1 (1X) dicamba applied 3 DBP. Crop injury ratings were taken 1, 2, 3, and 4 weeks after treatment (WAT). Across application timings, predicted sweetpotato plant injury 1, 2, 3, and 4 WAT increased from 3 to 22%, 3 to 32%, 2 to 58%, and 1 to 64% as dicamba rate increased from 0 to 70 g ha−1 (1/8X), respectively. As dicamba rate increased from 1/512X to 1/8X, predicted No. 1 yield decreased from 127 to 55%, 103 to 69%, 124 to 31%, and 124 to 41% of the non-treated control for applications made 1, 3, 5, and 7 WAP, respectively. Similarly, as dicamba rate increased from 1/512X to 1/8X, predicted marketable yield decreased from 123 to 57%, 107 to 77%, 121 to 44%, and 110 to 53% of the non-treated control for applications made 1, 3, 5, and 7 WAP, respectively. Dicamba residue (5.3 to 14.3 parts per billion) was detected in roots treated with 1/16X or 1/8X dicamba applied 5 or 7 WAP and 1/64X dicamba applied 7 WAP with the highest residue detected in roots harvested from sweetpotato plants treated at 7 WAP. Collectively, care should be taken to avoid sweetpotato exposure to dicamba especially at 1/8X and 1/16X rates during the growing season.

Tolerance of Wheat to Soil Sodicity Can Be Better Detected through an Incremental Crop Tolerance Approach and Ascertained through Multiple Sowing Times

Soil sodicity is a significant crop production constraint around the world. Inherited tolerance is a precursor to pre-breeding and breeding tolerant cultivars. However, high yield per se and seasonal variability are potential limitations to identify real tolerance rather than escape correctly. To minimise this risk, we generated yield, yield components and supporting data at two times of sowing (TOS) of 15 lines representing four quadrants of a biplot from a sodic- vs. non-sodic yield dataset of 112 wheat lines trialled in the previous year. Data from sodic and non-sodic sites were investigated using three analytical approaches namely, simple ratio of yield (REI), ratio of genotypic effects (TI) after excluding site effects, and the incremental crop tolerance (ICT) reflected as deviation from regression. REI and TI produced similar results showing ninelines to be tolerant, but only four lines namely, Scepter, Condo, WA345, and WA134 passed the ICT test. The tolerance comparison at the two TOSs differentiated lines tolerant at either or both TOSs. Association of Yield-ICT with leaf tissue mineral analysis and ICT for morphological traits was genotype specific, thus not usable invariably for detection of tolerant germplasm. Hence, we conclude that (i) focussing on yield rather than yield components or tissue tests, (ii) following the ICT approach, and (iii) evaluation at multiple sowing times will provide an accurate and rigorous test for identifying inherited tolerance that breeders and physiologists can reliably use. We anticipate our suggested approach to be applicable globally across crops.

Sulfate enhances drought tolerance in foxtail millet seedlings by promoting ABA biosynthesis and inducing stomatal closure

Background and aims Sulfate, the main source of sulfur in natural soil, is critical for plant growth and development, as well as plant responses to environmental stress, including drought. However, our understanding of the detailed mechanisms of sulfate-modulated drought tolerance in crop plants is far from complete. In the present study, by using foxtail millet (Setaria italica L.), an emerging model crop, we investigated the possible mechanisms involved in sulfate-induced crop tolerance to drought stress. Methods A combination of biochemical and molecular approaches, as well as stomatal apertures analyses were applied to determine the effect of sulfate application on sulfur assimilation, ABA biosynthesis, and stomatal movement. Results Upon drought exposure, sulfate (4 mM) pretreatment significantly alleviated the decrease in relative water content in foxtail millet leaves. Exogenous sulfate increased endogenous sulfate content and markedly enhanced the enzyme activity of sulfite reductase (SiR) and O-acetylserine(thiol)lyase (OASTL), as well as levels of their transcripts, leading to an increase in cysteine (Cys) production in drought-stressed leaves. Furthermore, in comparison with drought stress alone, sulfate application significantly upregulated the transcriptional expression of SiABA3 and SiAAO3, which contributed to the increased ABA levels in the leaves of drought-stressed foxtail millet seedlings. Moreover, the addition of sulfate decreased stomatal aperture, thus resulting in reduced leaf water loss in foxtail millet exposed to drought. Conclusion Our data suggest that sulfate application was able to promote drought tolerance of foxtail millet plants, at least partially by increasing ABA biosynthesis and triggering stomatal closure.