Phenylalanine supply alleviates the drought stress in mustard (Brassica campestris) by modulating plant growth, photosynthesis, and antioxidant defense system

Physiological, cytological and multi-omics analysis revealed the molecular response of Fritillaria cirrhosa to Cd toxicity in Qinghai-Tibet Plateau

Fritillaria cirrhosa, an endangered plant endemic to plateau regions, faces escalating cadmium (Cd) stress due to pollution in the Qinghai-Tibet Plateau. This study employed physiological, cytological, and multi-omics techniques to investigate the toxic effects of Cd stress and detoxification mechanisms of F. cirrhosa. The results demonstrated that Cd caused severe damage to cell membranes and organelles, leading to significant oxidative damage and reducing photosynthesis, alkaloid and nucleoside contents, and biomass. Cd application increased cell wall thickness by 167.89% in leaves and 445.78% in bulbs, leading to weight percentage of Cd increases of 76.00% and 257.14%, respectively. PER, CESA, PME, and SUS, genes responsible for cell wall thickening, were significantly upregulated. Additionally, the levels of metabolites participating in the scavenging of reactive oxygen species, including oxidized glutathione, D-proline, L-citrulline, and putrescine, were significantly increased under Cd stress. Combined multi-omics analyses revealed that glutathione metabolism and cell wall biosynthesis pathways jointly constituted the detoxification mechanism of F. cirrhosa in response to Cd stress. This study provides a theoretical basis for further screening of new cultivars for Cd tolerance and developing appropriate cultivation strategies to alleviate Cd toxicity.

Metallic allies in drought resilience: Unveiling the influence of silver and zinc oxide nanoparticles on enhancing tomato (Solanum lycopersicum) resistance through oxidative stress regulation

The escalating influence of environmental changes has heightened the physiological challenges faced by plants, with drought stress increasingly recognized as a critical global issue significantly impeding affecting the crop productivity. This study investigates the effectiveness of metal nano particles such as zinc oxide nanoparticles (ZnO NPs) and silver nanoparticles (Ag NPs) in mitigating drought stress in Solanum lycopersicum. The foliar application of ZnO NPs (500 ppm) and/or Ag NPs (500 ppm), individually or in combination, significantly alleviated drought stress-induced. This mitigation was evidenced by enhanced antioxidant enzymes activity viz., catalase (64%), peroxidase (76%), superoxide dismutase (78%), chlorophyll content (31%) & photosynthesis (37%), and protein levels (15%). Furthermore, ZnO NPs and Ag NPs effectively mitigated oxidative stress and lipid peroxidation, as evidence by reduced accumulation of malondialdehyde (11%). Remarkably, the combined application of ZnO NPs and Ag NPs expedited the water-splitting capacity and facilitated electron exchange through redox reactions under drought stress. Consequently, these enhancements positively influenced the morpho-physiological characteristics such as height (28%), fresh weight (31%), dry weight (29%) and net photosynthetic rate (37%) of S. lycopersicum. These findings underscore the promising potential of metal NPs, such as ZnO NPs and Ag NPs, in mitigating drought stress, offering valuable insights for sustainable crop production amidst evolving environmental challenges.

Mitigation of drought stress in maize and sorghum by humic acid: differential growth and physiological responses

BACKGROUND

Drought is a major determinant for growth and productivity of all crops, including cereals, and the drought-induced detrimental effects are anticipated to jeopardize world food security under the ongoing global warming scenario. Biostimulants such as humic acid (HA) can improve drought tolerance in many cereals, including maize and sorghum. These two plant species are genetically related; however, maize is more susceptible to drought than sorghum. The physiological and biochemical mechanisms underlying such differential responses to water shortage in the absence and presence of HA, particularly under field conditions, are not fully understood.

RESULTS

Herein, the effects of priming maize and sorghum seeds in 100 mg L-1 HA on their vegetative growth and physiological responses under increased levels of drought (100%, 80%, and 60% field capacity) were simultaneously monitored in the field. In the absence of HA, drought caused 37.0 and 58.7% reductions in biomass accumulation in maize compared to 21.2 and 32.3% in sorghum under low and high drought levels, respectively. These responses were associated with differential retardation in overall growth, relative water content (RWC), photosynthetic pigments and CO2 assimilation in both plants. In contrast, drought increased root traits as well as H2O2, malondialdehyde, and electrolyte leakage in both species. HA treatment significantly improved the growth of both plant species under well-watered and drought conditions, with maize being more responsive than sorghum. HA induced a 29.2% increase in the photosynthetic assimilation rate in maize compared to 15.0% in sorghum under high drought level. The HA-promotive effects were also associated with higher total chlorophyll, stomatal conductance, RWC, sucrose, total soluble sugars, total carbohydrates, proline, and total soluble proteins. HA also reduced the drought-induced oxidative stress via induction of non-enzymic and enzymic antioxidants at significantly different extents in maize and sorghum.

CONCLUSION

The current results identify significant quantitative differences in a set of critical physiological biomarkers underlying the differential responses of field-grown maize and sorghum plants against drought. They also reveal the potential of HA priming as a drought-alleviating biostimulant and as an effective approach for sustainable maize and sorghum production and possibly other crops in drought-affected lands.

Carotenoid Accumulation in the Rhododendron chrysanthum Is Mediated by Abscisic Acid Production Driven by UV-B Stress

Rhododendron chrysanthum (R. chrysanthum) development is hampered by UV-B sunlight because it damages the photosynthetic system and encourages the buildup of carotenoids. Nevertheless, it is still unclear how R. chrysanthum repairs the photosynthetic system to encourage the formation of carotenoid pigments. The carotenoid and abscisic acid (ABA) concentrations of the R. chrysanthum were ascertained in this investigation. Following UV-B stress, the level of carotenoids was markedly increased, and there was a strong correlation between carotenoids and ABA. The modifications of R. chrysanthum's OJIP transient curves were examined in order to verify the regulatory effect of ABA on carotenoid accumulation. It was discovered that external application of ABA lessened the degree of damage on the donor side and lessened the damage caused by UV-B stress on R. chrysanthum. Additionally, integrated metabolomics and transcriptomics were used to examine the changes in differentially expressed genes (DEGs) and differential metabolites (DMs) in R. chrysanthum in order to have a better understanding of the role that ABA plays in carotenoid accumulation. The findings indicated that the majority of DEGs were connected to carotenoid accumulation and ABA signaling sensing. To sum up, we proposed a method for R. chrysanthum carotenoid accumulation. UV-B stress activates ABA production, which then interacts with transcription factors to limit photosynthesis and accumulate carotenoids, such as MYB-enhanced carotenoid biosynthesis. This study showed that R. chrysanthum's damage from UV-B exposure was lessened by carotenoid accumulation, and it also offered helpful suggestions for raising the carotenoid content of plants.

Chitosan combined with humic applications during sensitive growth stages to drought improves nutritional status and water relations of sweet potato

The current decline in freshwater resources presents a significant global challenge to crop production, a situation expected to intensify with ongoing climate change. This underscores the need for extensive research to enhance crop yields under drought conditions, a priority for scientists given its vital role in global food security. Our study explores the effects of using humic and chitosan treatments to alleviate drought stress during critical growth phases and their impact on crop yield and water efficiency. We employed four different irrigation strategies: full irrigation, 70% irrigation at the early vine development stage, 70% irrigation during the storage root bulking stage, and 85% irrigation across both stages, complemented by full irrigation in other periods. The plants received either humic treatments through foliar spray or soil application, or chitosan foliar applications, with tap water serving as a control. Our findings highlight that the early vine development stage is particularly vulnerable to drought, with a 42.0% decrease in yield observed under such conditions. In normal growth scenarios, foliar application of humic substances significantly improved growth parameters, resulting in a substantial increase in yield and water efficiency by 66.9% and 68.4%, respectively, compared to the control treatment under full irrigation. For sweet potatoes irrigated with 70% water at the storage root bulking stage, ground application of humic substances outperformed both foliar applications of chitosan and humic in terms of yield results. The highest tuber yield and water efficiency were attained by combining chitosan and humic ground applications, regardless of whether 70% irrigation was used at the storage root bulking stage or 85% irrigation during both the early vine development and storage root bulking stages.

Comprehensive review: Effects of climate change and greenhouse gases emission relevance to environmental stress on horticultural crops and management

Global climate change exerts a significant impact on sustainable horticultural crop production and quality. Rising Global temperatures have compelled the agricultural community to adjust planting and harvesting schedules, often necessitating earlier crop cultivation. Notably, climate change introduces a suite of ominous factors, such as greenhouse gas emissions (CGHs), including elevated temperature, increased carbon dioxide (CO2) concentrations, nitrous oxide (N2O) and methane (CH4) ozone depletion (O3), and deforestation, all of which intensify environmental stresses on crops. Consequently, climate change stands poised to adversely affect crop yields and livestock production. Therefore, the primary objective of the review article is to furnish a comprehensive overview of the multifaceted factors influencing horticulture production, encompassing fruits, vegetables, and plantation crops with a particular emphasis on greenhouse gas emissions and environmental stressors such as high temperature, drought, salinity, and emission of CO2. Additionally, this review will explore the implementation of novel horticultural crop varieties and greenhouse technology that can contribute to mitigating the adverse impact of climate change on agricultural crops.

Enhancing Wheat Crop Resilience to Drought Stress through Cellulolytic Microbe-Enriched Cow Dung Vermicompost

BACKGROUND

Wheat, an important cereal crop, is commonly cultivated in arid and semiarid areas, and therefore, it often experiences water deficit conditions. The consequences of induced stress on wheat can be mitigated through vermicompost amendments. To address drought stress on wheat seedlings, a pot experiment was conducted in the wire-house in which two contrasting wheat cultivars, Faisalabad-08 (drought-tolerant) and Galaxy-13 (drought-sensitive), were exposed to three water level conditions: well-watered [D0, 70% of field capacity (FC)], moderate drought (D1, 45% FC), and severe drought (D2, 30% FC). Four rates of vermicompost, derived from cow dung enriched with cellulolytic microbes, were applied (VT0, control; VT1, 4 t ha-1; VT2, 6 t ha-1; and VT3, 8 t ha-1) to the experiment. Data on various physiological, biochemical, and enzymatic antioxidants were recorded.

RESULTS

Our results demonstrated that the drought treatments significantly reduced nutrient accumulation, chlorophyll and SPAD values, and carotenoid content in both cultivars where the maximum reduction was recorded for severe drought stress. Nonetheless, the application of vermicompost significantly improved these traits, and statistically maximum chlorophyll contents, SPAD value, and total carotenoid contents were observed for VT1 in both cultivars under drought treatments. While the lowest chlorophyll and carotenoid contents were recorded for untreated replicated pots. Among the cultivars, Faisalabad-08 exhibited greater resistance to drought, as evidenced by higher values of the aforementioned traits compared to Galaxy-13. Soil-applied vermicompost also showed a positive influence on antioxidant enzyme activities in both wheat cultivars grown under well-watered as well as water-scarce conditions.

CONCLUSIONS

The findings of this study revealed that drought conditions substantially decreased the enzymatic antioxidants and physiological and biochemical attributes of the wheat crop. However, soil-applied vermicompost, particularly at an optimum rate, had a positive impact on the wheat seedlings under drought conditions. Moving forward, exploring the potential of utilizing cellulolytic microbe-enriched cow dung vermicompost stands as a promising avenue to mitigate the detrimental effects of water stress on wheat. Further research in this direction could offer substantial insights into enhancing wheat resilience and productivity under water stress conditions.

Amino Acids Biostimulants and Protein Hydrolysates in Agricultural Sciences

The effects of different types of biostimulants on crops include improving the visual quality of the final products, stimulating the immune systems of plants, inducing the biosynthesis of plant defensive biomolecules, removing heavy metals from contaminated soil, improving crop performance, reducing leaching, improving root development and seed germination, inducing tolerance to abiotic and biotic stressors, promoting crop establishment and increasing nutrient-use efficiency. Protein hydrolysates are mixtures of polypeptides and free amino acids resulting from enzymatic and chemical hydrolysis of agro-industrial protein by-products obtained from animal or plant origins, and they are able to alleviate environmental stress effects, improve growth, and promote crop productivity. Amino acids involve various advantages such as increased yield and yield components, increased nutrient assimilation and stress tolerance, and improved yield components and quality characteristics. They are generally achieved through chemical or enzymatic protein hydrolysis, with significant capabilities to influence the synthesis and activity of some enzymes, gene expression, and redox-homeostasis. Increased yield, yield components, and crop quality; improved and regulated oxidation-reduction process, photosynthesis, and physiological activities; decreased negative effects of toxic components; and improved anti-fungal activities of plants are just some of the more important benefits of the application of phenols and phenolic biostimulants. The aim of this manuscript is to survey the impacts of amino acids, different types of protein hydrolysates, phenols, and phenolic biostimulants on different plants by presenting case studies and successful paradigms in several horticultural and agricultural crops.

Optimizing Sugarcane Growth, Yield, and Quality in Different Ecological Zones and Irrigation Sources Amidst Environmental Stressors

The imbalanced use of fertilizers and irrigation water, particularly supplied from groundwater, has adversely affected crop yield and harvest quality in sugarcane (Saccharum officinarum L.). In this experiment, we evaluated the impact of potassium (K) and micronutrients [viz. Zinc (Zn), Iron (Fe), and Boron (B)] application and irrigation water from two sources, viz. canal, and tube well water on sugarcane growth, yield, and cane quality under field trails. Water samples from Mardan (canal water) and Rahim Yar Khan (tube well water) were analyzed for chemical and nutritional attributes. The results revealed that tube well water's electrical conductivity (EC) was three-fold that of canal water. Based on the EC and total dissolved salts (TDS), 83.33% of the samples were suitable for irrigation, while the sodium adsorption ratio (SAR) indicated only a 4.76% fit and a 35.71% marginal fit compared with canal water. Furthermore, the application of K along with B, Fe, and Zn had led to a significant increase in cane height (12.8%, 9.8%, and 10.6%), cane girth (15.8%, 15.6%, and 11.6%), cane yield (13.7%, 12.3%, and 11.5%), brix contents (14%, 12.2%, and 13%), polarity (15.4%, 1.4%, and 14%), and sugar recovery (7.3%, 5.9%, and 6%) in the tube well irrigation system. For the canal water system, B, Fe, and Zn increased cane height by 15.3%, 13.42%, and 11.6%, cane girth by 13.9%, 9.9%, and 6.5%, cane yield by 42.9%, 43.5%, and 42%, brix content by 10.9%, 7.7%, and 8%, polarity by 33.4%, 28%, and 30%, and sugar recovery by 4.0%, 3.9%, and 2.0%, respectively, compared with sole NPK application. In conclusion, the utilization of tube well water in combination with canal water has shown better results in terms of yield and quality compared with the sole application of canal water. In addition, the combined application of K and B significantly improved sugarcane yields compared with Zn and Fe, even with marginally suitable irrigation water.

Comparative Analysis of Growth and Physiological Responses of Sugarcane Elite Genotypes to Water Stress and Sandy Loam Soils

Stumpy irrigation water availability is extremely important for sugarcane production in Pakistan today. This issue is rising inversely to river flow due to inadequate water distribution and an uneven rainfall pattern. Sugarcane growth faces a shortage of available water for plant uptake due to the low water-holding capacity of sandy loam soil, particularly under conventional flood irrigation methods. To address this problem, sugarcane clones were evaluated for their agronomic and physiological traits under conditions of low water availability in sandy loam soil. Ten cane genotypes, HSF-240, SPF-213, CPF-249, CP 77-400, S2008-FD-19, S2006-US-469, S2007-AUS-384, S2003-US-633, S2003-US-127, and S2006-US-658, were exposed to four levels of water deficit created through skip irrigations. These deficit levels occurred during the 9th, 11th, 13th, and 16th irrigations at alternate deficit levels between 2020 and 2022. Physiological data were collected during the tillering and grand growth stages (elongation) in response to the water deficit. The sugarcane clones S2006-US-658, S2007-AUS-384, and HSF-240 exhibited resistance to low water availability at both the tillering and grand growth stages. Following them, genotypes S2006-US-658, S2007-AUS-384, and HSF-240 performed better and were also found to be statistically significant. Clones susceptible to water deficit in terms of growth and development were identified as CP 77-400, S2008-FD-19, S2006-US-469, and S2003-US-633. These genotypes showed reduced photosynthetic rate, transpiration rate, stomatal conductance, relative water content, cane yield, and proline content under stressed conditions. Therefore, genotypes S2006-US-658, S2007-AUS-384, and HSF-240 were better performers concerning physiological traits under water deficit and sandy loam soil in both years. Moreover, a significant positive correlation was assessed between agronomic traits and photosynthetic rats. This study highlights that sugarcane can sustain its growth and development even with less irrigation frequency or moisture availability, albeit with certain specific variations.