Although boron (B) is essential micronutrient, higher soil B concentrations become toxic to the plants in arid and semi-arid regions of the world. Very little is known about the pH related nutrient ...solubility, including transpiration-mediated B uptake by plants. The effects of high B (200 μM) and low to high pH (3.0-10.0) on B toxicity, transpiration and nutrient uptake by wheat and rapeseed were studied. Plants were grown for 5 weeks under greenhouse conditions and analyzed for elements concentrations. Regardless of high B or not, low pH favored in the higher B accumulation in roots and shoots of both plant species. However, both plant species exhibited a differential B uptake pattern in roots and shoots. Both low and high pH levels in combination with high B decreased the plant biomass, transpiration, N and Mg concentrations, whereas increased the K, Ca, S, Cu, Fe, Mn and Zn concentrations. With the increase in pH 3.0-10.0, excess B decreased the Cl concentrations in wheat and rapeseed. In conclusion, low pH and high B supply enhanced the transpiration-assisted B uptake by plants although pH alone had little effects on B concentrations. Furthermore, nutritional disorder caused by high B in conjunction with low to high pH (3.0-10.0) inhibited the plant growth and transpiration.
Phosphorus (P) availability in alkaline soils of arid and semi-arid regions is a major constraint for decreased crop productivity. Use of plant growth promoting rhizobacteria (PGPR) may enhance plant ...growth through the increased plant antioxidation activity. Additionally, PGPR may increase nutrient uptake by plants as a result of induced root exudation and rhizosphere acidification. The current study was aimed to investigate combined effects of P and Pesudomonas putida (PGPR) on chickpea growth with reference to antioxidative enzymatic activity and root exudation mediated plant nutrient uptake, particularly P. Half of the seeds were soaked in PGPR solution, whereas others in sterile water and latter sown in soils. Plants were harvested 8 weeks after onset of experiment and analyzed for leaf nutrient contents, antioxidant enzymes activities and organic acids concentrations. Without PGPR, P application (+P) increased various plant growth attributes, plant uptake of P and Ca, soil pH, citric acid and oxalic acid concentrations, whereas decreased the leaf POD enzymatic activity as compared to the P-deficiency. PGPR supply both under −P and +P improved the plant growth, plant uptake of N, P, and K, antioxidative activity of SOD and POD enzymes and concentrations of organic acids, whereas reduced the rhizosphere soil pH. Growth enhancement by PGPR supply was related to higher plant antioxidation activity as well as nutrient uptake of chickpea including P as a result of root exudation mediated rhizosphere acidification.
•Without inoculation, P-deficiency was responsible for plant growth reduction.•Growth enhancement by PGPR in both P-treatments was due to plant-induced antioxidation activity.•PGPR supply also enhanced the root exudation mediated leaf nutrient accumulation in chickpea.•PGPR inoculation not only increased the P uptake by plants, but also improved the N and K nutrition.
Nutrient disorder and presence of disease-causing agents in soilless media negatively influence the growth of muskmelon. To combat these issues, use of environmentally-friendly sanitation techniques ...is crucial for increased crop productivity. The study was conducted under greenhouse and field conditions to investigate the effect of two different sanitation techniques: steaming and formalin fumigation on various media's characteristics and their impact on muskmelon yield. Media: jantar, guar, wheat straw and rice hull and peat moss of 10% air-filled porosity and sanitized with formalin and steaming. Steaming of guar, jantar, and wheat straw increased the phosphorus (P) and potassium (K) concentrations by 13.80-14.86% and 6.22-8.45% over formalin fumigation. Likewise, P and K concentrations in muskmelon were higher under steaming. Steaming significantly inhibited the survival of Fusarium wilt sp. melonis, root knot nematode sp. meloidogyne and nitrifying bacteria in media than formalin fumigation. In conclusion, steaming decreased the prevalence of nitrifying bacteria and pathogens which thus improved the NO
-N:NH
-N ratios, P and K nutritional balance both in the media and muskmelon transplants. Hence, steaming as an environment-friendly approach is recommended for soilless media. Further, optimization of steaming for various composts with different crops needs to be investigated with steaming teachnique.
•Without inoculation, accumulation of salt toxic ions was responsible for shoot growth reduction.•PGPRconferred rice tolerance to individual stresses due to induced plant antioxidation activity.•PGPR ...supply excluded Na+ from rice leaves which enhanced the plant tolerance to NaCl+high B.
Plant growth promoting rhizobacteria (PGPR) confer plant tolerance to abiotic stresses like salinity and high boron (B) due to limited uptake of toxic ions as well as increased production of antioxidants. The current study was aimed to investigate whether particular PGPR strain is responsible either for the decreased uptake of B together with salt toxic ions or to promote rice growth through an efficient antioxidative system under combined stresses of salinity and high B. Rice seedlings were maintained in pots according to completely randomized design (CRD) and stressed with high B (0.92mmolL−1 or 10ppm) and NaCl (150mmolL−1 or ECw of 14.7dSm−1) for 8 weeks. Half of the pots received Bacillus pumilus-inoculated rice seedlings, whereas the other half received un-inoculated ones. Subsequently, plants were harvested and analyzed for mineral composition and antioxidation activity either using atomic absorption spectrometer (AAS) or spectrophotometer. In the absence of PGPR, NaCl salinity significantly enhanced the leaf B and salt toxic ions concentrations, thereby resulting in the shoot growth reduction when compared with the control. Similarly, combined treatment increased the leaf and xylem sap B as compared to NaCl alone, however, remained insignificant for salt toxic ions. Contrary, NaCl+high B decreased the leaf B concentrations as compared to high B alone. Application of PGPR enhanced the plant growth under individual stresses due to enhanced activity of certain of antioxidative enzymes. In combined treatment, B. pumilus showed a positive potential for limiting the Na+ accumulation in rice leaves, but not for leaf B. Moreover, limited uptake of Na+ resulted in the decreased plant antioxidation activity irrespective of increasing leaf B concentrations which in turn enhanced the rice tolerance.
Maize cultivated for dry grain covers approximately 197 million hectares globally, securing its position as the second most widely grown crop worldwide after wheat. Although spermidine and biochar ...individually showed positive impacts on maize production in existing literature, their combined effects on maize growth, physiology, nutrient uptake remain unclear and require further in-depth investigation. That's why a pot experiment was conducted on maize with spermidine and potassium enriched biochar (KBC) as treatments in Multan, Pakistan, during the year 2022. Four levels of spermidine (0, 0.15, 0.30, and 0.45mM) and two levels of potassium KBC (0 and 0.50%) were applied in completely randomized design (CRD). Results showed that 0.45 mM spermidine under 0.50% KBC caused significant enhancement in maize shoot length (11.30%), shoot fresh weight (25.78%), shoot dry weight (17.45%), root length (27.95%), root fresh weight (26.80%), and root dry weight (20.86%) over control. A significant increase in maize chlorophyll a (50.00%), chlorophyll b (40.40%), total chlorophyll (47.00%), photosynthetic rate (34.91%), transpiration rate (6.51%), and stomatal conductance (15.99%) compared to control under 0.50%KBC validate the potential of 0.45 mM spermidine. An increase in N, P, and K concentration in the root and shoot while decrease in electrolyte leakage and antioxidants also confirmed that the 0.45 mM spermidine performed more effectively with 0.50%KBC. In conclusion, 0.45 mM spermidine with 0.50%KBC is recommended for enhancing maize growth.
The current study aimed to improve the nitrogen recovery efficiency (NRE) of maize under the application of balanced proportions of ammoniacal-nitrogen (NH4+-N) and nitrate-nitrogen (NO3−-N) (1:1), ...as well as to determine economic impacts of such fertilizers on maize productivity. A 3-year field study was carried out in Sahiwal, Punjab, Pakistan during the 2018–2020 growing seasons with autumn maize. In parallel, multi-location field experiments were conducted at farmer’s fields in Sahiwal during the same growing seasons with autumn maize. The trials compared the effects of different fertilizers like urea, calcium ammonium nitrate (CAN), Sarsabz nitrophos (NP), nitrphos plus (NP Plus), and di-ammonium phosphate (DAP) on maize growth and yield, as well their economic efficiency. The results revealed that the application of Sarsabz NP and CAN increased the maize grain yield by 30%, 13%, 15%, 19%, 15%, and 9% as compared to the control, NP + urea, NP Plus + CAN, NP Plus + urea, DAP + urea, and DAP + CAN, respectively. In addition, the combined application of NP and CAN increased the total N and NO3−-N concentrations, whereas it decreased the NH4+-N concentrations in the soils. By contrast, NP + CAN increased the NH4+-N concentrations in maize leaves as compared to NO3−-N concentrations. Overall, the NRE of maize plants and the net return were higher under combined application of NP and CAN. In conclusion, CAN fertilizer increased the soil NO3−-N concentrations, which thus assimilated in the plants as NH4+ and improved the NRE of maize. Improved NRE thus enhanced maize yield and resulted in the maximum net return as compared to all other fertilizer combinations.
Plants show enhanced phytoremediation of heavy metal contaminated soils particularly in response to fungal inoculation. Present study was conducted to find out the influence of Nickel (Ni) toxicity ...on plant biomass, growth, chlorophyll content, proline production and metal accumulation by L. usitatissimum (flax) in the presence of Glomus intraradices . Flax seedlings of both inoculated with G. intraradices and non-inoculated were exposed to different concentrations i.e., 250, 350 and 500 ppm of Ni at different time intervals. Analysis of physiological parameters revealed that Ni depressed the growth and photosynthetic activity of plants. However, the inoculation of plants with arbuscular mycorrhizae (G. intraradices) partially helped in the alleviation of Ni toxicity as indicated by improved plant growth under Ni stress. Ni uptake of non- mycorrhizal flax plants was increased by 98% as compared to control conditions whereas inoculated plants showed 19% more uptake when compared with the non-inoculated plants. Mycorrhizal plants exhibited increasing capacity to remediate contaminated soils along with improved growth. Thus, AM assisted phytoremediation helps in the accumulation of Ni in plants to reclaim Ni toxic soils. Based on our findings, it can be concluded that the role of flax plants and mycorrhizal fungi is extremely important in phytoremediation.
The hormonal imbalances, including abscisic acid (ABA) and brassinosteroid (BR) levels, caused by salinity constitute a key factor in hindering spikelet development in rice and in reducing rice ...yield. However, the effects of ABA and BRs on spikelet development in plants subjected to salinity stress have been explored to only a limited extent. In this research, the effect of ABA and BRs on rice growth characteristics and the development of spikelets under different salinity levels were investigated. The rice seedlings were subjected to three different salt stress levels: 0.0875 dS m
(Control, CK), low salt stress (1.878 dS m
, LS), and heavy salt stress (4.09 dS m
, HS). Additionally, independent (ABA or BR) and combined (ABA+BR) exogenous treatments of ABA (at 0 and 25 μM concentration) and BR (at 0 and 5 μM concentration) onto the rice seedlings were performed. The results showed that the exogenous application of ABA, BRs, and ABA+BRs triggered changes in physiological and agronomic characteristics, including photosynthesis rate (Pn), SPAD value, pollen viability, 1000-grain weight (g), and rice grain yield per plant. In addition, spikelet sterility under different salt stress levels (CK, LS, and HS) was decreased significantly through the use of both the single phytohormone and the cocktail, as compared to the controls. The outcome of this study reveals new insights about rice spikelet development in plants subjected to salt stress and the effects on this of ABA and BR. Additionally, it provides information on the use of plant hormones to improve rice yield under salt stress and on the enhancement of effective utilization of salt-affected soils.
Arid and semi-arid soils are low in organic matter and have poor fertility, making them a serious threat to crop production. Most organic amendments, such as crop residues and farmyard manure, are ...short lived because of rapid decomposition. Incubation and pot studies were conducted to assess the impact of wheat straw biochar (produced at 350 °C) on temporal changes in soil microbial biomass and fertility status and to evaluate the efficacy of biochar for maize production in the top layer of Typic calciargid. The incubation study compared four levels of biochar (control, 0.5, 1.0 and 2.0% on a w/w basis of soil) and two fertilizer rates, i.e., unfertilized (no NPK fertilizer) and fertilized (nitrogen, P2O5 and K2O with rates of 125, 80 and 52.5 mg kg−1 soil, respectively). After incubation, the 2.0% biochar significantly improved the soil cation exchange capacity, organic carbon and microbial biomass carbon by up to 35, 59 and 26%, respectively, while decreasing the soil pH by up to 1.5% compared to that of the control treatment. When fertilized, the 2.0% biochar improved the soil’s available phosphorous, extractable potassium and total nitrogen by up to 59, 39 and 28%, respectively, compared to those of the control. The results from the pot experiment showed that using the 1% biochar with fertilizer significantly increased the maize dry biomass and grain yield by up to 57 and 72%, respectively, compared to those of the control. Additionally, the nitrogen and phosphorus recoveries from the mineral fertilizers improved significantly (up to 26 and 38%, respectively) when using the 1.0% biochar compared to those of the control. Conclusively, the addition of 1.0% biochar significantly improved maize growth and yield by enhancing nutrient recovery from mineral fertilizer and improving soil properties.
•Without inoculation, higher shoot boron (B) accumulation was responsible for tomato shoot growth reduction.•Bacillus pumilus (PGPR) limited the shoot B accumulation only at moderate level of B ...supply (B2).•PGPR conferred tolerance in B-stressed plants through the induced plant antioxidation activity.
High soil boron (B) concentrations in arid and semi-arid regions of the world are responsible for decreased crop productivity. However, the use of plant growth promoting rhizobacteria (PGPR) can improve the plant growth under stress conditions like high B either due to limited uptake of B or enhanced antioxidants production, as PGPR have been shown to enhance the resistance in plants against various abiotic stresses. A pot experiment was conducted under green house conditions according to completely randomized design (CRD) and comprised of four levels of B (0.45, 10, 20, and 50mg B kg−1 soil) either with or without PGPR. Plants were grown for 10 weeks after onset of experiment and analyzed for mineral composition including B and antioxidation activity. Shoot fresh weight, shoot dry weight and leaf chlorophyll contents were inhibited to increasing levels of B. Interestingly, shoot K+ concentration tended to increase with increasing B levels, particularly at 50mg B kg−1 soil; third level of B (B3). Similarly, highest shoot B concentrations were observed at high levels of B supply (B3) as compared to all other treatments. Likewise, with the increase in external B supply, antioxidant enzymes activities and proline contents in tomato shoot were enhanced. Bacillus pumilus inoculation significantly improved the shoot fresh weight and dry weight of unstressed (control) as well as B-stressed plants. In general, B. pumilus inoculation enhanced the plant antioxidation activity, particularly superoxide dismutase (SOD) and catalase (CAT) antioxidant enzymes. Contrary, the interaction between high B and B. pumilus remained insignificant for limiting the shoot B uptake except for second level of B (B2) which decreased the shoot B accumulation by 21% as compared to non-inoculated B2. Our results suggest that PGPR inoculation confer tolerance in B-stressed plants through the induced plant antioxidation activity. Additionally, PGPR inoculation reduces the shoot B accumulation, however, differential response of shoot B inhibition is expected to increasing B concentrations.
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