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Weed infestation is one of the most damaging biotic factors to limit crop production by competing with the crop for space, water, and nutrients. Different conventional approaches are being used to cope with weed infestation, including labor intensive manual removal and the use of soil-degrading, crop-damaging, and environment-deteriorating chemical herbicides. The use of chemicals for weed control has increased 2-fold after the green revolution and their non-judicious use is posing serious threats to mankind, animals, and biodiversity. The detrimental effects of these approaches have shifted the researchers' attention from the last two decades towards alternate, sustainable, and eco-friendly approaches to cope with weed infestation. The recent approaches of weed control, including plant and microbial allelopathy have gained popularity during last decade. Farmers still use conventional methods, but the majority of farmers are very passionate about organic agriculture and describe it as a slogan in the developed world. The effectiveness of these approaches lies in host specificity by selective bacteria and differential response towards weeds and crops. Moreover, the crop growth promoting effect of microorganisms (allelopathic bacteria) possessing various growth promoting traits, that is, mineral solubilization, phytohormone production, and beneficial enzymatic activity, provide additional benefits. The significance of this review lies in the provision of a comprehensive comparison of the conventional approaches along with their potential limitations with advanced/biological weed control approaches in sustainable production. In addition, the knowledge imparted about weed control will contribute to a better understanding of biological control methods. [ABSTRACT FROM AUTHOR]

Drought stress has a significant challenge to crop growth, reproduction, and yield in arid regions. Microbes associated with desert plants offer a promising solution by enhancing moisture and nutrient uptake, mitigating water stress, and ultimately boosting crop growth and yield. In this study, the bacteria isolated from the rhizosphere of native plant Aerva javanica, found in the Cholistan desert, were assessed for their effectiveness to promote chickpea seedlings growth. A total of 21 drought-tolerant rhizobacterial strains were isolated and characterized, with a focus on their ability to produce exopolysaccharide (EPS) and 1-aminocyclopropane-1-carboxylic acid-deaminase (ACC-deaminase) under water-deficit conditions. These conditions were simulated using polyethylene glycol (PEG) 6000 in the growth medium. Notably, strains CD23 and CD21 exhibited the highest EPS production ability, yielding 10.9 and 10.4 mg L-1 of EPS, respectively, under PEG-induced drought stress however, a minute reduction in EPS production was observed under normal conditions. Similarly, ACC-deaminase activity was significant, measuring 3.2 and 3.2 µM mg-1 protein for strains CD23 and CD21, respectively. Further assessments were conducted to evaluate the drought tolerance of these strains at various PEG-6000 levels in jar trials. The strains CD23 and CD21 demonstrated promising results in enhancing chickpea growth. Subsequently, through partial gene sequencing of the 16S rRNA, these strains were identified as Acinetobacter sp. strain CD21 (accession number: MW829536) and Klebsiella sp. strain CD23 (accession number MW829537). The production of ACC-deaminase and EPS by these desert rhizobacteria may serve as crucial indicator for the development of inoculants that can promote chickpea growth under water-deficit conditions. [ABSTRACT FROM AUTHOR]

Catalase can decompose hydrogen peroxide in plants under controlled and stressed conditions. In a stressed environment, an increase in hydrogen peroxide production makes catalase activity a major defense system for plant growth. The current study was conducted to evaluate the catalase activity of the pre-isolated and identified bacterial strains Bacillus aryabhattai (AN30), Bacillus megaterium (AN24), Bacillus megaterium (AN31) and Bacillus megaterium (AN35) and their potential for rice seedling growth promotion. These strains were characterized for quantitative catalase, urease, siderophore and exopolysaccharide production using LB media. Subsequently, the effectiveness of these strains was checked by quantifying the catalase activity in the rhizosphere, roots and shoots of rice seedlings. The secretion of organic and phenolic compounds produced by the tested strains in liquid culture was also investigated. Plant growth parameters were also studied in a growth room trial. Our results showed that the strain AN24 showed the maximum catalase activity (1.36 mol cm−1), urease activity (1.35 mol cm−1) and exopolysaccharide (4.20 µg mL−1) and siderophore (2.32%) production in LB media. All tested strains showed significantly higher catalase activity in soil compared to the control. Among sole applications, strain AN24 showed better results; however, the consortium application of strains AN24 + AN30 + AN35 + AN31 showed the maximum improvement in dry biomass, shoot and root length, and increase in catalase activity of rice seedlings. The results showed that a consortium of these Bacillus strains with catalase activity has greater potential to enhance the antioxidant defense system and growth promotion of rice seedlings. However, further experimentation under natural conditions is required before using these strains as potential bioinoculants for improving rice growth and yield. [ABSTRACT FROM AUTHOR]

Application of untreated wastewater for vegetable production in peri-urban areas enters into the food chain leading to compromised human health. The present study was planned to evaluate the potential of cadmium (Cd) tolerant bacterial strains in combination with foliar application of Jasmonic acid (JA) under Cd stress. The Cd tolerant bacterial strains were isolated from wastewater and characterized for the production of exopolysaccharides (EPS), siderophore, and indole acdetic acid (IAA) under in vitro studies. The four most efficient strains SS5, SS7, SS8, and SS10 were selected based on growth-promoting traits and further evaluated with different levels of JA (20 µmol L-1 and 40 µmol L-1) in jar trial. Cauliflower (hyperaccumulator) was used as a test crop with Cd levels (0 and 150 mg kg-1). Our results depicted that the use of consortium (SS7+SS8) along with a foliar application of JA (40 µmol L-1) significantly improved shoot dry weight (15.5%), root dry weight (28.4%), shoot length (23.7%), root length (37%), superoxide dismutase (29.8%), peroxidase dismutase (29.7%), catalase (31.7%) and POX (29.2%). However, 29 and 26% reduction in Cd concentration in shoots and roots was observed, respectively. It was concluded that the Klebsiella strains SS7 and SS8 with foliar application of JA is a potential biofertilizer and a phyto-stabilizer for metal-contaminated soils and recommended to reduce the Cd toxicity among crop plants. [ABSTRACT FROM AUTHOR]

Many farmers' incomes in developing countries depend on the cultivation of major crops grown in arid and semi-arid regions. The agricultural productivity of arid and semi-arid areas primarily relies on chemical fertilizers. The effectiveness of chemical fertilizers needs to improve by integration with other sources of nutrients. Plant growth-promoting bacteria can solubilize nutrients, increase plant nutrient uptake, and supplement chemical fertilizers. A pot experiment evaluated the promising plant growth-promoting bacterial strain's effectiveness in promoting cotton growth, antioxidant enzymes, yield, and nutrient uptake. Two phosphate solubilizing bacterial strains (Bacillus subtilis IA6 and Paenibacillus polymyxa IA7) and two zinc solubilizing bacterial strains (Bacillus sp. IA7 and Bacillus aryabhattai IA20) were coated on cotton seeds in a single as well as co-inoculation treatments. These treatments were compared with uninoculated controls in the presence and absence of recommended chemical fertilizer doses. The results showed the co-inoculation combination of Paenibacillus polymyxa IA7 and Bacillus aryabhattai IA20 significantly increased the number of bolls, seed cotton yield, lint yield, and antioxidants activities, including superoxide dismutase, guaiacol peroxidase, catalase, and peroxidase. Co-inoculation combination of Bacillus subtilis IA6 and Bacillus sp. IA16 promoted growth attributes, including shoot length, root length, shoot fresh weight, and root fresh weight. This co-inoculation combination also increased soil nutrient content. At the same time, Paenibacillus polymyxa IA7 + Bacillus aryabhattai IA20 increased nutrient uptake by plant shoots and roots compared. [ABSTRACT FROM AUTHOR]

Arid and semi-arid ecosystems are categorized as having degraded soils due to the limited availability of water and nutrients. The perennial shrubs in these regions have developed different ecological and physiological adaptations to cope with harsh conditions. The plant species vary in the chemical profile of their root exudates, which can induce variability in the microbial community in the rhizosphere. The present research has been conducted (i) to investigate the variation in composition, diversity, and structure of rhizosphere's bacterial community of desert plants; (ii) to identify plant-specific effects on the rhizosphere microbial community structure; and (iii) to determine the influence of soil moisture on the rhizosphere's microbial community and soil biological properties under stressful conditions. Ten desert plant species from the Cholistan desert were selected as test specimens. Bacterial communities from the rhizosphere of 10 plants of each species were explored. Soil samples were collected during monsoon (June–August) and dry months (March–May). Microbial community structure analyses were carried out through 16S rRNA sequencing by targeting V3 and V4 regions. Among tested plant species, the rhizosphere of Leptadenia pyrotechnica (S6 vs. S16), Aerva javanica (Burm. f.) Juss. ex Schult (S9 vs. S19), and Vachellia jacquemontii (Benth.) (S10 vs. S20) had greater microbial diversity in both seasons. Higher levels of microbial communities were found during monsoon season. Furthermore, Gammaproteobacteria were abundant in the rhizospheres of all studied plants during the monsoon season. In contrast, the rhizosphere was abundant with unidentified_Actinobacteria during the dry season. The rhizospheric soil was further analyzed for biological properties. The maximum microbial biomass carbon (165 mg kg–1) and microbial biomass nitrogen (6.7 mg kg–1) were found in the rhizosphere of Vachellia jacquemontii (Benth.) Benth during monsoon season. However, a minimum of microbial biomass carbon (119 mg kg–1) and microbial biomass nitrogen (4.2 mg kg–1) were found in the rhizosphere of Cleome pallida Kotschy during dry seasons. The diversified microbial community structure and biological properties enable desert plants to cope with adverse climate conditions. [ABSTRACT FROM AUTHOR]