Insights into metabolic profile and redox adjustment during ammonium-induced salt acclimation in sorghum plants.

Sorghum bicolor, a versatile cereal grain, holds significant agronomic importance globally and plays a crucial role in addressing food insecurity. However, salinity, a major abiotic stress, poses a threat to food production by reducing soil fertility and hindering plant growth and yield. In this study, we investigated the potential of Cistus salviifolius water extract (CSE) in mitigating salt stress in sorghum plants. Salt stress severely impacted plant growth, biomass, and chlorophyll production, and reduced indole-3-acetic acid (IAA) levels, which negatively affected plant development. Salt stress also led to the buildup of reactive oxygen species (ROS), hence, resulting in oxidative harm to sorghum plants and also affecting their carbon and nitrogen metabolism. On the other hand, CSE treatments increased IAA and chlorophyll content which promoted growth under stress. Furthermore, this extract exhibited strong ROS scavenging capacity and safeguarded plants against oxidative stress by enhancing the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, and glutathione reductase) and increasing the production of osmolytes. Additionally, CSE treatments enhanced the activities of carbon/nitrogen enzymes (phosphoenolpyruvate carboxylase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, and glutamine synthase), promoting energy synthesis and crop growth. This led to a significant increase in sorghum growth in salted soil with the highest rise recorded for 5mg/L of CSE (an increase of 48.23% and 158.36% in length and weight compared to the salt control), which highlights this extract's potential as a biostimulant to enhance crop tolerance to salinity and contribute to sustainable agriculture.

Different methods of silicon application attenuate salt stress in sorghum and sunflower by modifying the antioxidative defense mechanism

A pot experiment was carried out to explore the role of glycinebetaine (GB) as foliar spray foliar on two pea (Pisum sativum L.) varieties (Pea 09 and Meteor Fsd) under saline and non-saline conditions. Thirty-two-day-old plants were subjected to two levels 0 and 150 mM of NaCl stress. Salt treatment was applied in full strength Hoagland’s nutrient solution. Three levels 0, 5 and 10 mM of GB were applied as foliar treatment on 34-day-old pea plants. After 2 weeks of foliar treatment with GB data for various growth and physiochemical attributes were recorded. Rooting-medium applied salt (150 mM NaCl) stress decreased growth, photosynthesis, chlorophyll, chlorophyll fluorescence and soluble protein contents, while increasing the activities of enzymatic (POD and CAT) and non-enzymatic (ascorbic acid and total phenolics) antioxidant enzymes. Foliar application of GB decreased root and shoot Na+ under saline conditions, while increasing shoot dry matter, root length, root fresh weight, stomatal conductance (gs), contents of seed ascorbic acid, leaf phenolics, and root and shoot Ca2+ contents. Of three GB (0, 5, 10 mM) levels, 10 mM proved to be more effective in mitigating the adverse effects of salinity stress. Overall, variety Pea 09 showed better performance in comparison to those of var. Meteor Fsd under both normal and salinity stress conditions. GB-induced modulation of seed ascorbic acid, leaf phenolics, gs, and root Ca2+ values might have contributed to the increased plant biomass, reduction of oxidative stress, increased osmotic adjustment and better photosynthetic performance of pea plants under salt stress.

This work aimed to study the regulation of K+/Na+ homeostasis and the physiological responses of salt-treated sorghum plants [Sorghum bicolor (L.) Moench] grown with different inorganic nitrogen (N) sources. Four days after sowing (DAS), the plants were transferred to complete nutrient solutions containing 0.75 mM K+ and 5 mM N, supplied as either NO3− or NH4+. Twelve DAS, the plants were subjected to salt stress with 75 mM NaCl, which was applied in two doses of 37.5 mM. The plants were harvested on the third and seventh days after the exposure to NaCl. Under the salt stress conditions, the reduction of K+ concentrations in the shoot and roots was higher in the culture with NO3− than with NH4+. However, the more conspicuous effect of N was on the Na+ accumulation, which was severely limited in the presence of NH4+. This ionic regulation had a positive influence on the K+/Na+ ratio and the selective absorption and transport of K+ in the plants grown with NH4+. Under control and salt stress conditions, higher accumulation of free amino acids and soluble proteins was promoted in NH4+ grown roots than NO3− grown roots at both harvesting time, whereas higher accumulation of soluble sugars was observed only at 7 days of salt stress exposure. Unlike the NH4+ grown plants, the gas exchanges of the NO3− grown plants were reduced after 7 days of salt stress. These results suggest that external NH4+ may limit Na+ accumulation in sorghum, which could contribute to improving its physiological and metabolic responses to salt stress.

The whole-plant daily carbon balance (the 24-h sum of photosynthetic input of substrate carbon per plant and loss of carbon through respiration) is the CO2 exchange measure that relates most closely to crop production rates. Water stress reduces the photosynthetic input, reducing both leaf area and photosynthetic rate per unit leaf area. Respiratory losses are reduced more or less proportionately. A less-than-proportional loss was observed during osmotic adjustment in sorghum (Sorghum bicolor (L) Moench): the metabolic cost of storing photosynthate and using it for osmotic adjustment was less than the cost of converting it to new biomass. A slightly increased metabolic cost is often found under salt stress but, in sorghum plants that were salinized and then water stressed, the adverse effects of salt were mitigated by decreased water loss rates and enhanced osmotic adjustment during water stress. More tests involving combined salt and water stress are needed.

Picloram (4‐amino‐3,5,6‐trichloropicolinic acid) residues in soil may occur as a result of weed control practices on cropland and injure subsequent crops. This study was conducted to determine how soil residues of picloram affected the growth and dry matter production of sorghum (Sorghum bicolor (L.) Moench) ‘Topland’ and soybeans (Glycine max (L.) Merr.) ‘Hill’ grown in soil at various time intervals after picloram had been applied.The potassium salt of picloram was applied at 1.12 kg/ha and incorporated by disking into a Wilson clay loam soil 1½, 3, 6, 7, 12, 14, 16, 19, and 26 months before planting of sorghum and soybeans in the Spring of 1972 and 1973. Soil, sorghum, and soybeans were analyzed for picloram content at time of harvest. After maturing, crop plants were counted and harvested by clipping two rows, 4.1 m long at the soil level in each plot. Plants were weighed and oven‐dried for dry matter determination. Germination tests were conducted with harvested sorghum seed.Sorghum was grown on picloram‐treated soils 12 months after application without reduction in plant numbers, dry matter production, flowering, or germination. No picloram was detected in sorghum seed (immature and mature) produced by plants seeded 6 or 12 months after application of herbicide to the soil. Because soybeans were sensitive to small amounts of picloram in the soil, they should not be grown in a picloram‐treated clay soil for at least 2 years after application. Earlier planting risks possible reduction in stand and dry‐matter production in situations similar to this study.

Water scarcity and soil salinization are increasingly becoming limiting factors in food production, including olives, a major fruit crop in several parts of the world. Investigating historical olives, which are the last resort for genetic resources, is essential due to their natural resilience to drought and salinity, making them valuable for breeding stress-tolerant cultivars and ensuring sustainable olive production. In this study, four historic olive cultivars ('Nabali', 'Mehras', 'Frantoio', and 'Manzanillo') were investigated under both drought and salinity stresses. These cultivars also preserve local biodiversity, support traditional agriculture, and offer economic opportunities through unique, heritage-based olive oils. Drought and salt stress in olives are assessed through physiological [the ratio of variable to maximum fluorescence (Fv/Fm), relative water content (RWC)], biochemical (proline content), and molecular (stress-responsive genes) analyses to evaluate stress tolerance. Under salinity and drought stress, RWC decreased in all olive cultivars, with drought having the most severe impact. 'Nabali' exhibited the highest salinity tolerance, while all cultivars showed similar sensitivity to drought. Proline levels remained stable in 'Mehras' but decreased under salinity stress in 'Frantoio', 'Manzanillo', and 'Nabali'. Higher proline accumulation under drought suggested better drought tolerance than salinity in these cultivars. Photosynthetic efficiency (Fv/Fm) declined under salinity and drought stress in all cultivars, with drought causing a more significant reduction. 'Manzanillo' showed the highest sensitivity to drought, while the other cultivars maintained moderate efficiency under stress. 'Manzanillo' and 'Mehras' exhibited the highest number of differentially expressed genes (DEGs) under both drought and salinity stress, with 'Manzanillo' showing 2,934 DEGs under drought and 664 under salinity stress, while 'Mehras' had 2,034 and 2,866 DEGs, respectively. 'Nabali' demonstrated the strongest salinity-specific response, with 3,803 DEGs under salinity stress compared to 1,346 under drought. 'Frantoio' consistently had the lowest number of DEGs, with 345 under drought and 512 under salinity stress, indicating a more stable transcriptional response. Comparative analyses between drought and salinity conditions revealed significant variations, with 'Manzanillo' showing 2,599 unique DEGs under drought relative to salinity stress, while 'Nabali' exhibited 2,666 DEGs under salinity stress relative to drought. The major novel upregulated genes under salinity stress were Xyloglucan endotransglucosylase hydrolase (7 fold in 'Nabali' and 6.9 fold in 'Mehras'). The novel drought genes detected in 'Frantoio' included Phytosulfokines 3 (4.9 fold), while Allene oxide synthase (6.5 fold) and U-box domain-containing (6.4 fold) were detected in 'Manzanillo'. The data revealed both novel and common stress-specific biomarkers under both salinity and drought stress, which can potentially be utilized in olive breeding and genetic improvement programs to mitigate stress.

BackgroundSorghum is an important food staple in the developing world, with the capacity to grow under severe conditions such as salinity, drought, and a limited nutrient supply. As a serious environmental stress, soil salinization can change the composition of rhizosphere soil bacterial communities and induce a series of harm to crops. And the change of rhizospheric microbes play an important role in the response of plants to salt stress. However, the effect of salt stress on the root bacteria of sorghum and interactions between bacteria and sorghum remains poorly understood.ResultsThe purpose of this study was to assess the effect of salt stress on sorghum growth performance and rhizosphere bacterial community structure. Statistical analysis confirmed that low high concentration stress depressed sorghum growth. Further taxonomic analysis revealed that the bacterial community predominantly consisted of phyla Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Bacteroidetes and Firmicutes in sorghum rhizosphere soil. Low salt stress suppressed the development of bacterial diversity less than high salt stress in both bulk soil and planted sorghum soil. Different sorghum development stages in soils with different salt concentrations enriched distinctly different members of the root bacteria. No obviously different effect on bacterial diversity were tested by PERMANOVA analysis between different varieties, but interactions between salt and growth and between salt and variety were detected. The roots of sorghum exuded phenolic compounds that differed among the different varieties and had a significant relationship with rhizospheric bacterial diversity. These results demonstrated that salt and sorghum planting play important roles in restructuring the bacteria in rhizospheric soil. Salinity and sorghum variety interacted to affect bacterial diversity.ConclusionsIn this paper, we found that salt variability and planting are key factors in shifting bacterial diversity and community. In comparison to bulk soils, soils under planting sorghum with different salt stress levels had a characteristic bacterial environment. Salinity and sorghum variety interacted to affect bacterial diversity. Different sorghum variety with different salt tolerance levels had different responses to salt stress by regulating root exudation. Soil bacterial community responses to salinity and exotic plants could potentially impact the microenvironment to help plants overcome external stressors and promote sorghum growth. While this study observed bacterial responses to combined effects of salt and sorghum development, future studies are needed to understand the interaction among bacteria communities, salinity, and sorghum growth.

Soil salinization and alkalization severely inhibit agriculture. However, the response mechanisms of cotton to salt stress or alkali stress are unclear. Ionomics and metabolomics were used to investigate salt and alkali stresses in cotton roots and leaves. Compared with the control, salt-treated and alkali-treated cotton plants showed 51.8 and 53.0% decreases in biomass, respectively. Under salt stress, the concentration of N decreased in roots but increased in leaves, and the concentrations of P and K increased in roots but decreased in leaves. Salt stress inhibited Ca, B, N, and Fe uptake and Mg, K, P, S, and Cu transport, but promoted Mo, Mn, Zn, Mg, K, P, S, and Cu uptake and Mo, Mn, Zn, B, N, and Fe transport. Under alkali stress, the concentrations of N and P in roots and leaves decreased, while the concentrations of K in roots and leaves increased. Alkali stress inhibited P, Ca, S, N, Fe, and Zn uptake and N, P, Mg and B transport, but promoted K, Mn, Cu, Mo, Mg, and B uptake and K, Mn, Cu, Mo, Fe, and Zn transport. Under salt stress in the leaves, 93 metabolites increased, mainly organic acids, amino acids, and sugars, increased in abundance, while 6 decreased. In the roots, 72 metabolites increased, mainly amino acids, organic acids, and sugars, while 18 decreased. Under alkali stress, in the leaves, 96 metabolites increased, including organic acids, amino acids, and sugars, 83 metabolites decreased, including organic acids, amino acids, and sugars; In the roots, 108 metabolites increased, including organic acids, amino acids, and sugars. 83 metabolites decreased, including organic acids and amino acids. Under salt stress, cotton adapts to osmotic stress through the accumulation of organic acids, amino acids and sugars, while under alkali stress, osmoregulation was achieved via inorganic ion accumulation. Under salt stress, significant metabolic pathways in the leaves and roots were associated with amino acid and organic acid metabolism, sugar metabolism was mainly used as a source of energy, while under alkali stress, the pathways in the leaves were related to amino acid and linoleic acid metabolism, β-Oxidation, TCA cycle, and glycolysis were enhanced to provide the energy needed for life activities. Enhancing organic acid accumulation and metabolism in the roots is the key response mechanism of cotton to alkalinity.

Abstract: Research on the application of silicate fertilizer and manure to growth, brix level, and yield of sorghum (Sorghum bicolor (L.) Moench) was investigated to find ways to increase sorghum productivity in the dry land. The research method used was an experimental method that was set in a randomized block design consisting of 9 treatments namely control (Si0P0), without silicate and manure, 5 tones/ha (Si0P5), without silicate and manure 10 tones/ha (Si0P10), silicate 100 kg/ha and without manure (Si100P0), silicate 100 kg/ha and manure 5 tones/ha (Si100P5), silicate 100 kg/ha and manure 10 tones/ha (Si100P10), silicate 200 kg/ha and without manure (Si200P0), silicate 200 kg/ha and manure 5 tones/ha (Si200P5), and silicate 200 kg/ha and manure 10 tones/ha (Si200P10). Each treatment was replicated 3 times and the size of the plot was 6x6 m2. The results indicated that the application of silicate fertilizer and manure could significantly increase yield and brix levels. Application of silicate fertilizer of 200 kg/ha and manure 5 tonnes/ha gave higher results for the production of sorghum was 6056 kg/ha. However, the growth of sorghum was not affected significantly to the growth of sorghum plants. Keywords: Silicate Fertilizer (Si); Manure; Sorghum Plant

Abstract. Prisillia RMA, Susilowati A, Solichatun. 2021. Screening of phosphate solubilizing bacteria from sugarcane plant rhizosphere as biofertilizer agent for sorghum growth (Sorghum bicolor). Asian J Trop Biotechnol 18: 37-45. Sorghum plants (Sorghum bicolor L.) development in Indonesia is still behind due to limited application in a few locations. Sorghum is a crop that can be grown on marginal terrain. The scarcity of nutrients in marginal land necessitates the addition of nutrients. Biofertilizer is a biological fertilizer that comprises microorganisms that act as nutrient suppliers and promote plant growth in the soil. This research included soil sampling, prospective testing, and screening to identify a biofertilizer solubilizing bacterium candidate. Bacterial screening entails bacterial identification, bacterial growth measurement, and a media pH test. The biofertilizer application experiment used a completely randomized design (CRD) with two factors: the first component was the addition of phosphate solubilizing bacteria, which was divided into two levels, without bacteria, and with bacteria. The second factor was variations in the NPK (Nitrogen, Phosphorus, Potassium) fertilizer concentrations of 0, 25, 50, and 100%, which correspond to 0; 0.625; 1.25, and 2.5 g NPK / plant, respectively. The vegetative phase of sorghum growth was observed for 50 days, and height, the number of leaves, leaves color, root length, fresh weight, and dry weight of sorghum plants were determined using ANOVA and DMRT test levels of 5%. Seven isolates of phosphate solubilizing bacteria were obtained from this research. Two possibly superior isolates were produced as biofertilizers: BPF 5 and 12 I. Compared to control treatments, adding BPF 5 and 12 I isolate in combination with varied NPK fertilizer concentrations significantly altered sorghum growth parameters, such as plant height, root length, fresh weight, and dry weight. The addition of BPF 12 I isolates at 0% and 25% fertilizer concentrations results in sorghum growth.

Sweet sorghum (Sorghum bicolor [L.] Moench) is a plant that can be an alternative for the production of bioethanol in semi-arid regions. The objective of this work was to evaluate sweet sorghum 'BRS 506' under salt and water stress. The experimental design was in randomized blocks, in a factorial scheme (4x4), with the first factor referring to the electrical conductivities of the irrigation water (1.5; 3.0; 4.5; and 6.0 dS m-1) and the second refers to irrigation depths (53, 67, 85 and 95% of crop evapotranspiration). Gas exchange, leaf water status, leaf sugars and plant growth were evaluated. Salt and water stress cause negative effects on the growth of sweet sorghum 'BRS 506'. Salt stress causes disturbances in gas exchange and sugar levels. Sweet sorghum 'BRS 506' is tolerant to combined salt and water stress.

Five species of mangroves (Bruguiera gymnorrhiza, Excoecaria agallocha, Heritiera fomes, Phoenix paludosa and Xylocarpus granatum) were investigated with respect to their photosynthesis rate, chlorophyll content, mesophyll conductance, specific leaf area, stomatal conductance and photosynthetic nitrogen use efficiency under saline (15–27 PPT) and non-saline (1.8–2 PPT) conditions. Some inorganic elements were estimated from the leaf samples to compare the concentrations with change in salinity. Elevated assimilation rate coupled with increased chlorophyll content, more mesophyll and stomatal conductance and higher specific leaf area in non-saline condition indicates that these mangroves can grow well even with minimal salinity in soil. In B. gymnorrhiza, E. agallocha and P. paludosa the optimum PAR acquisition for photosynthesis was higher under salt stress, while the maximal rate of assimilation was lower even with minimal salinity. H. fomes and X. granatum followed the opposite trend, where the peak photosynthesis rate was lower under non-saline conditions even at a higher irradiance than in the saline forest. This indicates less affinity of H. fomes and X. granatum to high substrate salinity. Accumulation of Na+ increased in plants in saline substrate, while in most of the species, salinity imposed reduction in Ca+ and Mg+ uptake. Increased K+ content can be attributed to high substrate level K+ in non-saline soil. Trace amount of salinity induced Cu++ detected in leaves of H. fomes may impart some toxic effects. Photosynthetic nitrogen use efficiency increased in non-saline soil that can be attributed to higher photosynthetic peak in most of the species and/or lower nitrogen accumulation in plant samples.

The efficiency of silicon (Si) foliar spraying in sorghum plants can be increased with new sources that may enhance the uptake of the beneficial element with reflexes in physiology. This study investigated the effect of foliar application of Si on different sources of absorption, gas exchange, and growth in sorghum plants, based on the hypothesis that there is a differential response to specific sources and concentrations of Si. An experiment was conducted in a completely randomized design with three replicates (in triplicate). The treatments consisted of five Si sources (nanosilica, silicic acid, stabilized sodium, potassium silicate, and potassium silicate) and four concentrations of Si (0, 0.5, 1.0, and 1.5 g L−1 of Si). Foliar spraying of Si on sorghum plants was effective at increasing the absorption of the beneficial element and the gas exchange of the plant. Nanosilica stood out as an alternative source of Si, and a promising option for foliar spraying in sorghum crops, as it promoted high uptake of the element by the plant. This source also promoted a high photosynthetic rate for both potassium silicate and alkaline silicate. In this study, spraying of 0.88 g L−1 (Si-alkali) and 0.84 g L−1 (Si-potassium) on sorghum at the phenological stages V4 and V8 (four and eight fully expanded leaves respectively) and R1 (beginning of flowering) was promising because it increased plant growth, reduced water loss through transpiration, and had a positive impact on gas exchange.

Salinity is one of the most common abiotic stresses in the world. It negatively affects the growth and development of sweet sorghum (Sorghum bicolor L. Moench). It significantly reduces germination and seedling growth parameters. The present study was carried out to evaluate the impact of four salinity levels (0, 100, 200, and 300 mM) on the germination and seedling growth parameters of four sweet sorghum genotypes (Erdurmus, Uzun, Srg 156, and BSS 424) and on their ion content (Na, K, Ca, and Mg). The results indicate that under nonsaline conditions, the germination percentage (GP) of all genotypes was 100%, and Erdurmus was identified as the earliest germinating genotype. The BSS 424 genotype showed a significant reduction in germination index (GI), ranging from 8.33% at 100 mM to 0.89% at 300 mM, while Erdurmus and Srg 156 showed the lowest decreases, with mean values of 15.801 and 13.901, respectively. The highest root fresh weight (RFW) value was observed in the control for all the genotypes, while Erdurmus showed the lowest decrease. Moreover, the highest decrease in Mg (0.24%) and Ca (0.17%) content was observed in Uzun, and the lowest K content was identified in BSS 424 (0.5%), whereas the highest Na content was also determined in Uzun (3.12%). Considering all the results, salt stress above 200 mM significantly affected the germination and seedling growth parameters. Therefore, lower concentrations should be taken into consideration for sustainable sorghum production.