Growth, Water Status, Physiological, Biochemical and Yield Response of Stay Green Sorghum (Sorghum bicolor (L.) Moench) Varieties-A Field Trial Under Drought-Prone Area in Amhara Regional State, Ethiopia

Response of Sorghum bicolor genotypes for yield and yield components and organic carbon storage in the shoot and root systems

Sorghum is a vital food and feed crop in the world's dry regions. Developing sorghum cultivars with high biomass production and carbon sequestration can contribute to soil health and crop productivity. The objective of this study was to assess agronomic performance, biomass production and carbon accumulation in selected sorghum genotypes for production and breeding. Fifty sorghum genotypes were evaluated at three locations (Silverton, Ukulinga, and Bethlehem) in South Africa during 2022 and 2023 growing seasons. Significant genotype × location (p < 0.05) interactions were detected for days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), and grain yield (GY). The highest GY was recorded for genotypes AS115 (25.08 g plant-1), AS251 (21.83 g plant-1), and AS134 (21.42 g plant-1). Genotypes AS122 and AS27 ranked first and second, respectively, for all the carbon stock parameters except for root carbon stock (RCs), whereas genotype AS108 had the highest RCs of 8.87 g plant-1. The principal component analysis identified GY, DTH, PH, PB, SB, RB, RCs, RCs/SCs, total plant carbon stock (PCs), shoot carbon stock (SCs), and grain carbon stock (GCs) as the most discriminated traits among the test genotypes. The cluster analysis using agronomic and carbon-related parameters delineated the test genotypes into three genetic groups, indicating marked genetic diversity for cultivar development and enhanced C storage and sustainable sorghum production. The selected sorghum genotypes are recommended for further breeding and variety release adapted to various agroecologies in South Africa.

Determination of Morpho-Physiological Traits for Assessing Drought Tolerance in Sugarcane

Drought is a significant constraint to sugarcane productivity. Therefore, understanding how different varieties of sugarcane respond to drought stress can facilitate breeding programs and set up criteria for selecting drought-tolerant varieties. In the present study, we examined eight morpho-physiological traits to distinguish 40 sugarcane genotypes categorized into four groups based on significant differences in cane yield under non-stressed conditions and reduction of cane yield under drought-stressed conditions. The study was conducted during the formative stage in a greenhouse, encompassing both control and drought conditions. Drought treatments resulted in significant changes and differences in the mean values of various morpho-physiological traits. The hierarchical clustering analysis, utilizing stay-green traits such as higher chlorophyll fluorescence ratio (Fv/Fm), leaf chlorophyll content (SPAD), leaf relative water content (RWC), and lower leaf rolling score (LR), leaf drying score (LD), and drought recovery score (DR), successfully grouped 40 sugarcane genotypes into four major clusters, similar to the previously categorized groups. Correlation analysis showed significant relationships among cane yield, reduction of cane yield under drought conditions, and the stay-green traits. Our results demonstrated that morpho-physiological traits contributing to the "stay-green" phenotypes could be useful as selection criteria for drought tolerance in sugarcane.

The update and transport of aluminum nanoparticles in plants and their biochemical and molecular phototoxicity on plant growth and development: A systematic review

As aluminum nanoparticles (Al-NPs) are widely used in our daily life and various industries, Al-NPs has been becoming an emerging pollution in the environment. The impact of this NP has been attracting more and more attention from the scientific communities. In this review, we systematically summarized the interactions, uptake, and transport of Al-NPs in the plant system. Al-NPs can enter plants through different pathways and accumulate in various tissues, leading to alter plant growth and development. Al-NPs also affected root, shoot, and leaf characteristics as well as changing nutrient uptake and distribution and inducing oxidative stress via excess reactive radical generation, thereby impairing plant defense systems. Additionally, Al-NPs altered gene expression, which involved in various signaling pathways and metabolic processes in plants, that further altered plants susceptible or tolerant to stressors. The review also emphasized the effects of Al-NP size, surface charge, concentration, and exposure duration on plant growth and development. In the future, more research should be focused on mechanisms underlying Al-NPs phytotoxicity and potential risk to humans and off-target species.

A non-specific lipid transfer protein, NtLTPI.38, positively mediates heat tolerance by regulating photosynthetic ability and antioxidant capacity in tobacco

Non-specific lipid transfer proteins (nsLTPs) play an important role in plant growth and stress resistance; however, their function in tobacco remains poorly understood. Therefore, to explore the function of NtLTP in response to high temperature, we identified an NtLTPI.38 from tobacco, obtained its overexpression and knockout transgenic plants, and further studied their response to heat stress (42 °C). The results showed that NtLTPI.38 overexpression in tobacco reduced chlorophyll degradation, alleviated the high temperature damage to photosynthetic organs, and enhanced the photosynthetic capacity of tobacco under heat stress. NtLTPI.38 overexpression in heat-stressed tobacco increased the contents of soluble sugar and protein, proline, and flavonoid substances, reduced the relative conductivity, and decreased H₂O₂, O₂^•-, and MDA accumulation, and increased the enzymatic antioxidant activities, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), compared to wild type (WT) and knockout mutant plants. RT-PCR confirmed that the expression levels of antioxidant enzymes and thermal stress-related genes were significantly upregulated under thermal stress in overexpression plants. Therefore, NtLTPI.38 enhanced heat tolerance in tobacco by mitigating photosynthetic damage and improving osmoregulation and antioxidant capacity. These results provided the theoretical basis and a potential resource for further breeding projects to improve heat tolerance in plants.

Sorghum in dryland: morphological, physiological, and molecular responses of sorghum under drought stress

Droughts negatively affect sorghum's productivity and nutritional quality. Across its diversity centers, however, there exist resilient genotypes that function differently under drought stress at various levels, including molecular and physiological. Sorghum is an economically important and a staple food crop for over half a billion people in developing countries, mostly in arid and semi-arid regions where drought stress is a major limiting factor. Although sorghum is generally considered tolerant, drought stress still significantly hampers its productivity and nutritional quality across its major cultivation areas. Hence, understanding both the effects of the stress and plant response is indispensable for improving drought tolerance of the crop. This review aimed at enhancing our understanding and provide more insights on drought tolerance in sorghum as a contribution to the development of climate resilient sorghum cultivars. We summarized findings on the effects of drought on the growth and development of sorghum including osmotic potential that impedes germination process and embryonic structures, photosynthetic rates, and imbalance in source-sink relations that in turn affect seed filling often manifested in the form of substantial reduction in grain yield and quality. Mechanisms of sorghum response to drought-stress involving morphological, physiological, and molecular alterations are presented. We highlighted the current understanding about the genetic basis of drought tolerance in sorghum, which is important for maximizing utilization of its germplasm for development of improved cultivars. Furthermore, we discussed interactions of drought with other abiotic stresses and biotic factors, which may increase the vulnerability of the crop or enhance its tolerance to drought stress. Based on the research reviewed in this article, it appears possible to develop locally adapted cultivars of sorghum that are drought tolerant and nutrient rich using modern plant breeding techniques.

Drought Tolerance and Application of Marker-Assisted Selection in Sorghum

Simple Summary

Sorghum is a climate-resilient crop grown in limited rainfall areas globally. However, climate change has increased temperature and shortened rainfall durations, which has constrained crop yield. We reviewed mechanisms of drought tolerance and application of marker-assisted selection in sorghum. Marker-assisted selection uses DNA molecular markers to map quantitative trait loci (QTL) associated with stay-green. Stg1, Stg2, Stg3, Stg4, Stg3A, and Stg3B QTLs associated with stay-green and high yield, have been mapped in sorghum. These QTLs are used for introgression into the senescent sorghum varieties through marker-assisted backcrossing.

Abstract

Sorghum is an important staple food crop in drought prone areas of Sub-Saharan Africa, which is characterized by erratic rainfall with poor distribution. Sorghum is a drought-tolerant crop by nature with reasonable yield compared to other cereal crops, but such abiotic stress adversely affects the productivity. Some sorghum varieties maintain green functional leaves under post-anthesis drought stress referred to as stay-green, which makes it an important crop for food and nutritional security. Notwithstanding, it is difficult to maintain consistency of tolerance over time due to climate change, which is caused by human activities. Drought in sorghum is addressed by several approaches, for instance, breeding drought-tolerant sorghum using conventional and molecular technologies. The challenge with conventional methods is that they depend on phenotyping stay-green, which is complex in sorghum, as it is constituted by multiple genes and environmental effects. Marker assisted selection, which involves the use of DNA molecular markers to map QTL associated with stay-green, has been useful to supplement stay-green improvement in sorghum. It involves QTL mapping associated with the stay-green trait for introgression into the senescent sorghum varieties through marker-assisted backcrossing by comparing with phenotypic field data. Therefore, this review discusses mechanisms of drought tolerance in sorghum focusing on physiological, morphological, and biochemical traits. In addition, the review discusses the application of marker-assisted selection techniques, including marker-assisted backcrossing, QTL mapping, and QTL pyramiding for addressing post-flowering drought in sorghum.

Plant response to silver nanoparticles: a critical review

Although several metal ions/metal nanoparticles (NPs) are toxic to both plants and animals, some of them are used as nutrients and growth promoters. Plants exposed to silver nanoparticles (Ag-NPs) have shown both beneficial and harmful effects. All concentrations of Ag-NPs are not effective for a given plant because any excess can block the passage of essential nutrients. Regulated treatment of plants by Ag-NPs may enhance their overall growth and development. It has been noticed that Ag-NPs decrease the mass of edible plants (Cucurbita pepo, Allium cepa, cabbage, and lettuce) and vegetables, but they also induce the germination of seeds in many cases. NPs interact with proteins, enzymes, and carbohydrates influencing the total biomass, root, and shoot growth of plants. Also, Ag-NPs act as an ethylene inhibitor and activate the antioxidants in onions. Their substantial quantity becomes deposited in onion leaves and bulbs. Size and concentration are the two major factors responsible for the increase/decrease of plant growth and biomass. Plants make adaptations to reduce the toxicity caused by Ag-NPs. In some cases, Ag-NPs induce root elongation and increase chlorophyll, carbohydrate, proteins, rate of photosynthesis and inhibit the biosynthesis of ethylene. This review article provides a comprehensive overview of both the beneficial and adverse effects of Ag-NPs on germination, growth, development, physiological, and biochemical characteristics of a wide range of edible and crop plants. We have also critically discussed: the chemistry, toxicity, uptake, translocation, and accumulation of Ag-NPs in plant systems.

Short-time irrigation on young olive tree (Olea europaea L. cv. Chemlali) with untreated industrial poultry wastewater: investigation of growth parameters and leaves chemical composition

The purpose of this study was to evaluate the short-term irrigation effect with industrial poultry wastewater on young olive trees (Olea europaea L. cv. Chemlali). Industrial poultry wastewater can be considered as a bio-fertilizer due to its richness in nutritive elements (SO₄^2-, HCO₃^-, total nitrogen, and K⁺). The physicochemical analysis of wastewater showed a high concentration of TSS, COD, BOD, COT, NO₃^-, and conductivity. Measurements indicated that poultry wastewater enhanced plant growth, leaves dry matter, and ashes in comparison with tap water, as well as poultry wastewater diluted with tap water; however, a decrease in total soluble sugars (glucose and fructose) was detected in leaves. The determination of fatty acid profile of young olive trees leaves irrigated with poultry wastewater showed richness on saturated fatty acids in comparison with mono- and poly-unsaturated ones. In addition, oleic acid (C_18:1) presented the lowest content in leaves of trees irrigated with poultry wastewater irrigation. According to those results, poultry wastewater lends itself to being a hydric alternative and at the same time a source of nutrients that can help fill the water deficit in semi-arid countries and avoid costly waste disposal for slaughterhouses.

Zinc oxide nanoparticles (ZnONPs) as a novel nanofertilizer: Influence on seed yield and antioxidant defense system in soil grown soybean (Glycine max cv. Kowsar)

Dearth of knowledge about the prospect of using Zinc (Zn) based nanoparticles (NPs) to enrich Zn-deficient soils with Zn warrants investigations into potential soil applications of ZnONPs for improving crop yield and plant health. Herein, we investigated the potential influence of ZnONPs on seed yield, focusing on particle size-, morphology-, and concentration-dependent responses of multiple antioxidant defense biomarkers, in soil-grown soybean (Glycine max cv. Kowsar) during its lifecycle of 120 d. We achieved this goal following a rational design strategy that enabled us to synthesize three types of morphologically different ZnONPs (spherical/ 38 nm, floral-like/ 59 nm, and rod-like/ >500 nm); all with high purity, triclinic crystal structure, and negative surface charge; and compared the toxicity with Zn2+ ions. Each pot received two seeds, placed in soil inoculated with N-fixing bacterium (Rhizobium japonicum) and grown in outdoor mesocosm for 120 d. Our findings demonstrated a significant particle size-, morphology-, and concentration-dependent influence of ZnONPs on seed yield, lipid peroxidation, and various antioxidant biomarkers in soybean. Our spherical 38 nm ZnONPs were the most protective compared to the floral-like 59 nm ZnONPs, rod-like >500 nm ZnONPs, and Zn2+ ions, particularly up to 160 mg Zn/kg. However, at the highest concentration of 400 mg Zn/kg, spherical 38 nm ZnONPs elicited the highest oxidative stress responses (H2O2 synthesis, MDA, SOD, CAT, POX) in soybean compared to the other two morphologically different ZnONPs tested. The concentration-response curves for the three types of ZnONPs and Zn2+ ions were nonlinear (nonmonotonous) for all the endpoints evaluated. The weight of evidence also suggested a differential nano-specific toxicity of ZnONPs compared to ionic Zn2+ toxicity in soybean. Our higher no-observed-adverse-effect-level (NOAEL) of 160 mg Zn/kg indicates the potential for using ZnONPs as a novel nanofertilizer for crops grown in Zn-deficient soils to improve crop yield, food quality and address malnutrition, globally.

Current status of plant metabolite-based fabrication of copper/copper oxide nanoparticles and their applications: a review

Since green mode of nanoparticles (NPs) synthesis is simple, advantageous and environment friendly relative to chemical and physical procedures, various plant species have been used to fabricate copper and copper oxide nanoparticles (Cu/CuO-NPs) owing to the presence of phytochemicals which often act as capping as well as stabilizing agent. These Cu/CuO-NPs are highly stable and used in the degradation of organic dyes like methylene blue and reduction of organic compounds such as phenols. They are also used as antibacterial, antioxidant and antifungal agent due to their cytotoxicity. They are also examined for agricultural crops growth and productivity. Cu-NPs increased the root and shoot growth of mung bean. In wheat plants, these particles reduced shoot growth; and enhanced the grain yield and stress tolerance through starch degradation. Similarly, CuO-NPs treated seedlings have shown reduced chlorophyll, carotenoid and sugar content, whereas proline and anthocyanins were increased in Brassica rapa seedlings. Overall, this review presents the recent understanding of plant-mediated Cu and CuO-NPs fabrication and their application in biomedicine, environmental remediation and agricultural practices. A comparison of the traditional/conventional method of fabrication of NPs with those of green protocols has also been made. Some misconception of copper chemistry has also been critically discussed in terms of oxidation and reduction reactions.

Foliar Application of Calcium and Growth Regulators Modulate Sweet Cherry (Prunus avium L.) Tree Performance

Cracking of sweet cherry (Prunus avium L.) fruits is caused by rain events close to harvest. This problem has occurred in most cherry growing regions with significant economic losses. Several orchard management practices have been applied to reduce the severity of this disorder, like the foliar application of minerals or growth regulators. In the present study, we hypothesized that preharvest spray treatments improve the physiological performance of sweet cherry trees and could also mitigate environmental stressful conditions. Effects of repeated foliar spraying of calcium (Ca), gibberellic acid (GA₃), abscisic acid (ABA), salicylic acid (SA), glycine betaine (GB), and the biostimulant Ascophyllum nodosum (AN) on the physiological and biochemical performance of ‘Skeena’ sweet cherry trees during two consecutive years (without Ca in 2015 and in 2016 with addition of Ca) were studied. Results showed that in general spray treatments improved the physiological performance and water status of the trees. AN and ABA sprays were demonstrated to be the best compounds for increasing yield and reducing cherry cracking as well as improving photosynthetic performance and leaf metabolites content. In conclusion, AN and ABA might be promising tools in the fruit production system.

Evaluating maize phenotype dynamics under drought stress using terrestrial lidar

BACKGROUND

Maize (Zea mays L.) is the third most consumed grain in the world and improving maize yield is of great importance of the world food security, especially under global climate change and more frequent severe droughts. Due to the limitation of phenotyping methods, most current studies only focused on the responses of phenotypes on certain key growth stages. Although light detection and ranging (lidar) technology showed great potential in acquiring three-dimensional (3D) vegetation information, it has been rarely used in monitoring maize phenotype dynamics at an individual plant level.

RESULTS

In this study, we used a terrestrial laser scanner to collect lidar data at six growth stages for 20 maize varieties under drought stress. Three drought-related phenotypes, i.e., plant height, plant area index (PAI) and projected leaf area (PLA), were calculated from the lidar point clouds at the individual plant level. The results showed that terrestrial lidar data can be used to estimate plant height, PAI and PLA at an accuracy of 96%, 70% and 92%, respectively. All three phenotypes showed a pattern of first increasing and then decreasing during the growth period. The high drought tolerance group tended to keep lower plant height and PAI without losing PLA during the tasseling stage. Moreover, the high drought tolerance group inclined to have lower plant area density in the upper canopy than the low drought tolerance group.

CONCLUSION

The results demonstrate the feasibility of using terrestrial lidar to monitor 3D maize phenotypes under drought stress in the field and may provide new insights on identifying the key phenotypes and growth stages influenced by drought stress.

Chromosomal aberrations, cell suppression and oxidative stress generation induced by metal oxide nanoparticles in onion (Allium cepa) bulb

In this work, we assess the phytotoxicity of various-sized metal oxide nanoparticles on cell cycle progression and induction of oxidative stress in onions.

Plant Response to Engineered Metal Oxide Nanoparticles

All metal oxide nanoparticles influence the growth and development of plants. They generally enhance or reduce seed germination, shoot/root growth, biomass production and physiological and biochemical activities. Some plant species have not shown any physiological change, although significant variations in antioxidant enzyme activity and upregulation of heat shock protein have been observed. Plants have evolved antioxidant defence mechanism which involves enzymatic as well as non-enzymatic components to prevent oxidative damage and enhance plant resistance to metal oxide toxicity. The exact mechanism of plant defence against the toxicity of nanomaterials has not been fully explored. The absorption and translocation of metal oxide nanoparticles in different parts of the plant depend on their bioavailability, concentration, solubility and exposure time. Further, these nanoparticles may reach other organisms, animals and humans through food chain which may alter the entire biodiversity. This review attempts to summarize the plant response to a number of metal oxide nanoparticles and their translocation/distribution in root/shoot. The toxicity of metal oxide nanoparticles has also been considered to see if they affect the production of seeds, fruits and the plant biomass as a whole.

Engineered Gold Nanoparticles and Plant Adaptation Potential

Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible.