Uptake In Rice Plants Research Articles

Stability of metal ion complexes with the synthetic phytosiderophore proline-2'-deoxymugineic acid.

Adequate micronutrient concentrations in crops are essential for human health and agricultural productivity. However, 30% of plants growing on cultivated soils worldwide are deficient in iron (Fe). Because of low micronutrient bioavailability, graminaceous plants have evolved to exude small molecules, called phytosiderophores, into the soil environment, which strongly complex and promote uptake of trace elements. The development of a synthetic phytosiderophore, proline-2'-deoxymugeneic acid (PDMA), has been shown to promote Fe uptake in rice plants; however, its binding capabilities with other metals, which may impact the ability to promote the uptake of Fe and other trace nutrient metals commonly found in soils, remain unknown. We conducted spectrophotometric titrations to determine the stability constants (logK) of PDMA complexes with Mn(II), Co(II), Cu(II), Ni(II), and Zn(II). We determined that PDMA complex stability constants correlated with: (1) the hydrolysis constants of metal ions (logKOH) in complexes; (2) the ionic potential of complexed metals; and (3) the corresponding complex stability constants of other mugineic acid type phytosiderophores, as well as the trishydroxamate microbial siderophore DFOB. These correlations demonstrate the potential, and limitations, on our ability to predict the stability of phytosiderophore complexes with metal ions with different physicochemical properties and with potentially different coordination structures.

Effects of Phosphorus and Potassium Supply on Photosynthetic Nitrogen Metabolism, Nitrogen Absorption, and Nitrogen Utilization of Hydroponic Rice

Phosphorus (P) and potassium (K) stress significantly affect the growth, physiological characteristics, and nutrient uptake of rice plants. This study investigated the photosynthetic nitrogen (N) metabolism, N uptake, and N utilization of plants under varied P and K supplies. Two local conventional high-yield rice varieties (Shennong 265 and Liaojing 294) were used. These varieties were subjected to the following hydroponic experimental treatments: HPHK (normal P and K concentrations), HPLK (normal P and 1/20 normal K concentration), LPHK (normal K and 1/20 normal P concentration), and LPLK (1/20 normal P and K concentrations). The results showed that the mesophyll cells had a relatively complete nuclear and chloroplast structures, and the antioxidant enzymes of the plants were significantly reduced under the HPHK treatment. Compared to the LP treatments (LPHK and LPLK), the HPHK treatment was found to have the following potential effects: effectively optimize plant configuration; promote leaf development (Pn, E, Ci, and Tr, chlorophyll, and leaf area index); significantly increase the N-metabolism-related enzyme activity of leaves and roots and the accumulation of N in the plant in the main growth stages; and significantly increase the rice yield and N-related efficiency. In conclusion, the HPHK treatment was found to be beneficial in improving the plant configuration, promoting photosynthetic N metabolism, and increasing grain yield and N-related utilization efficiency.

The improvement of soil properties in rice cropping systems using an integrated fertilization method to increase rice yield

AbstractThe global food crisis provides an impetus for agricultural green transformation via optimized fertilization methods. While organic substitution, green manure incorporation, and targeted fertilization sites have individually shown promise in enhancing rice yield, there is still a gap between optimized fertilization methods and achieving sustainable rice production. To explore the factors influencing rice yield across different fertilization strategies, we conducted a field experiment in Southern China encompassing five treatments, such as CK (no N input), RN (broadcasting urea with recommended N rates), RON (broadcasting organic–inorganic fertilizer with recommended N rates), RONS (side‐deep placement of organic–inorganic fertilizer with recommended N rates), and RONSA (coupled RONS with Azolla [Azolla pinnata R. Brown]). Using a Minimum Data Set approach, we identified the primary variables influencing soil properties and rice production, with a focus on soil physicochemical characteristics and bacterial communities. Further, the soil properties index (SPI), calculated by multiplying the linear score with the weight of each variable, served as an indicator of soil properties variations. Our findings revealed that RONSA significantly increased the SPI by 21.1% compared with RN, predominantly because of higher soil labile organic carbon (LOC) and available N (SAN) fractions (p < .05). N uptake in rice plants (23.9%–28.4%) increased dramatically under RONSA leading to higher rice yield (11.0%–16.9%) and NUE (30.2%–36.1%) than RN (p < .05). The enhancement in soil properties, characterized by increased LOC, SAN fractions, and bacterial community diversity, was essential in boosting rice yields, with dissolved inorganic N emerging as the dominant contributor. In summary, our results highlight the effectiveness of integrated fertilization approaches in enhancing soil properties, subsequently leading to improved rice yields and NUE. This fertilizer strategy holds promise for guiding field fertilization practices and advancing sustainable rice production.

Iron-modified biochar inhibiting Cd uptake in rice by Cd co-deposition with Fe oxides in the rice rhizosphere.

Fe-enriched biochar has proven to be effective in reducing Cd uptake in rice plants by enhancing iron plaque formation. However, the effect of Fe on biochar, especially the biochar with high S content, for Cd immobilization in rice rhizosphere was not fully understood. To obtain eco-friendly Fe-loaded biochar at a low cost, garlic straw, bean straw, and rape straw were chosen as the feedstocks for Fe-enhanced biochar production by co-pyrolysis with Fe2O3. The resulting biochars and Fe-loaded biochars were GBC, BBC, BRE, GBC-Fe, BBC-Fe, and BRE-Fe, respectively. XRD and FTIR analyses showed that Fe was successfully loaded onto the biochar. The pristine and Fe-containing biochars were applied at rates of 0% (BC0) and 0.1% in pot experiments. Results suggested that BBC-Fe caused the highest reduction in Cd content of rice grain, and the reductions were 67.9% and 31.4%, compared with BC0 and BBC, respectively. Compared to BBC, BBC-Fe effectively reduced Cd uptake in rice roots by 47.5%. The exchangeable and acid-soluble fraction of Cd (F1-Cd) in soil with BBC-Fe treatment was 37.6% and 63.7% lower than that of BC0 and BBC, respectively. Compared to BC0, soil pH was increased by 0.53 units with BBC-Fe treatment. BBC-Fe significantly increased Fe oxides (free Fe oxides, amorphous Fe oxides, and complex Fe oxides) content in the soil as well. DGT study demonstrated that BBC-Fe could enhance the mobility of sulfate in the rhizosphere, which might be beneficial for Cd fixation in the rhizosphere. Moreover, BBC-Fe increased the relative abundance of Bacteroidota, Firmicutes, and Clostridia, which might be beneficial for Cd immobilization in the rhizosphere. This work highlights the synergistic effect of loaded Fe and biochar on Cd immobilization by enhancing Cd deposited with Fe oxides.

Community-based mechanisms underlying the root cadmium uptake regulated by Cd-tolerant strains in rice (Oryza sativa. L).

In recent years, the problem of Cd pollution in paddy fields has become more and more serious, which seriously threatens the safe production of food crops and human health. Using microorganisms to reduce cadmium pollution in rice fields is a green, safe and efficient method, the complicated interactions between the microbes in rice roots throughout the process of cadmium absorption by rice roots are poorly understood. In this investigation, a hydroponic pot experiment was used to examine the effects of bacteria R3 (Herbaspirillum sp) and T4 (Bacillus cereus) on cadmium uptake and the endophytic bacterial community in rice roots. The results showed that compared with CK (Uninoculated bacterial liquid), the two strains had significant inhibitory or promotive effects on cadmium uptake in rice plant, respectively. Among them, the decrease of cadmium content in rice plants by R3 strain reached 78.57-79.39%, and the increase of cadmium content in rice plants by T4 strain reached 140.49-158.19%. Further investigation showed that the cadmium content and root cadmium enrichment coefficient of rice plants were significantly negatively correlated with the relative abundances of Burkholderia and Acidovorax, and significantly positively correlated with the relative abundances of Achromobacter, Agromyces and Acidocella. Moreover, a more complex network of microbes in rice roots inhibited rice plants from absorbing cadmium. These results suggest that cadmium uptake by rice plants is closely related to the endophytic bacterial community of roots. This study provides a reference scheme for the safe production of crops in cadmium contaminated paddies and lays a solid theoretical foundation for subsequent field applications.

Influence of arbuscular mycorrhizal fungi on mercury accumulation in rice (Oryza sativa L.): From enriched isotope tracing perspective

The microorganisms that co-exist between soil and rice systems in heavy metal-contaminated soil environments play important roles in the heavy metal pollution states of rice, as well as in the growth of the rice itself. In this study, in order to further examine the effects of soil microorganisms on the mercury (Hg) uptake of rice plants and determine potential soil phytoremediation agents, an enriched 199Hg isotope was spiked in a series of pot experiments to trace the absorption and migration of Hg and rice growth in the presence of arbuscular mycorrhizal fungi (AMF). It was observed that the AMF inoculations significantly reduced the Hg concentration in the rice. The Hg concentration in rice in the AMF inoculation group was between 52.82% and 96.42% lower than that in the AMF non-inoculation group. It was also interesting to note that the presence of AMF tended to cause Hg (especially methyl-Hg (Me199Hg)) to migrate and accumulate in the non-edible parts of the rice, such as the stems and leaves. Under the experimental conditions selected in this study, the proportion of Me199Hg in rice grains decreased from 9.91% to 27.88%. For example, when the exogenous Hg concentration was 0.1 mg/kg, the accumulated methyl-Hg content in the grains of the rice in the AMF inoculation group accounted for only 20.19% of the Me199Hg content in the rice plants, which was significantly lower than that observed in the AMF non-inoculated group (48.07%). AMF also inhibited the absorption of Hg by rice plants, and the decrease in the Hg concentration levels in rice resulted in significant improvements in growth indices, including biomass and micro-indexes, such as antioxidant enzyme activities. The improvements occurred mainly because the AMF formed symbiotic structures with the roots of rice plants, which fixed Hg in the soil. AMF also reduce the bioavailability of Hg by secreting a series of substances and changing the physicochemical properties of the rhizosphere soil. These findings suggest the possibility of using typical co-existing microorganisms for the remediation of soil heavy metal contamination and provide valuable insights into reducing human Hg exposure through rice consumption.

Efficacy of Soil and Foliar Boron Fertilizer on Boron Uptake and Productivity in Rice

This study examined the effect of B fertilizers applied by soil and foliar routes on the yield and total B uptake under glasshouse and field conditions. A high-yield rice variety, Sanpatong 1, was used in the experiments. In a pot experiment, soil B application produced a grain yield of 23.4 g pot−1, similar to the control treatment, but foliar B decreased grain yield by 14.9%. The total uptake of B was the highest at 2.5 mg pot−1 when soil B was applied, 66.7% higher than the in the control and foliar B application treatments, but there was no significant effect on the numbers of filled or unfilled grains. Similar responses of grain yield and total B uptake were observed in both conditions. Soil B application produced a grain yield of 4.7 t ha−1, similar to the control, but foliar B application decreased grain yield by 10.9%. The total uptake of B in the field was the highest at 4.7 mg m−2 when soil B was applied, being 42.4% higher than in the foliar B application and control treatments. This study indicates that the total uptake of B in rice plants can be successfully improved by applying soil B fertilizer, even though no effect was observed on productivity. The efficacy of B uptake in rice plants by soil B application is an interesting subject that should be further studied in greater detail to determine its utility in yield production, e.g., by splitting application times.

Effect of Biochar on Yield, Yield Components, and Macronutrients of Rice (Oryza sativa L.)

Biochar has recently caught researchers’ attention due to its potential of improving soil fertility and immobilizing pollutants and its emergence as a proper method of increasing crop yields. An experiment was conducted on the effect of chemical, ecological, and organic (biochar and compost) nutritional systems on yield and yield components of rice as a split-plot field experiment based on a randomized complete block design with three replications in two sites in Lahijan in 2018-2019. The experimental factors included nutrition at three levels (ecological, chemical, and control) as the main plot and the organic matter at four levels (urban waste compost, biochar, Azolla, and control) as the sub-plot. The combined application of chemical and organic fertilizers produced the highest grain yield, reflecting the positive effect of their combination on grain yield and yield components of rice cv. ‘Hashemi’. The results showed that the highest grain yield of 3699 kg ha-1 was related to the treatment of chemical fertilizer and biochar and the lowest (2209 kg ha-1 , i.e., a 40% decline) to the control (no chemical or biological fertilizer application). The highest number of fertile tillers and panicles per plant was obtained from the application of chemical fertilizer and biochar, the highest number of filled grains per panicle (116 grains) was observed in the application of chemical fertilizer and biochar at the university farm, and the lowest (84 grains) from the control (unfertilized treatment) at the Kateshal farm. The nutrient uptake was significantly higher in the chemical and biochar treatment than in the other treatments. Organic systems had varying impacts on rice yield and reduced the application of chemical fertilizers. Biochar contributed to increasing the growth, yield, and nutrient uptake of rice plants.

OsNRAMP5 Is a Major Transporter for Lead Uptake in Rice.

Lead (Pb) is one of the most toxic metals affecting human health globally. Food is an important source of chronic Pb exposure in humans. How Pb is taken up by rice, a staple food for over half of the global population, remains unknown. In the present study, we investigated the role of OsNRAMP5, a member of the NRAMP (Natural Resistance-Associated Macrophage Protein) transporter family, in Pb uptake by rice roots. Heterologous expression of OsNRAMP5 in yeast increased Pb uptake and sensitivity toward Pb. Knockout of OsNRAMP5 in rice by CRISPR/Cas9 gene editing resulted in significant decreases in root uptake of Pb and accumulation in rice shoots. The maximum influx velocity (Vmax) for Pb uptake of the knockout mutants was 70% lower than that of wild-type plants. When grown in Pb-contaminated paddy soil, OsNRAMP5 knockout mutants accumulated approximately 50 and 70% lower Pb concentrations in the grain and straw, respectively, than the wild type. OsNRAMP5 expression in rice roots was not affected by Pb exposure. These results indicate that OsNRAMP5 is a major transporter for Pb uptake in rice, in addition to its role in the uptake of manganese and cadmium. This study provides a mechanistic understanding of Pb uptake in rice plants and a potential strategy to limit Pb accumulation in rice grains.

Bacillus subtilis Synthesized Iron Oxide Nanoparticles (Fe3O4 NPs) Induced Metabolic and Anti-Oxidative Response in Rice (Oryza sativa L.) under Arsenic Stress.

Nanoparticle (NP) application is most effective in decreasing metalloid toxicity. The current study aimed to evaluate the effect of Bacillus subtiles synthesized iron oxide nanoparticles (Fe3O4 NPs) against arsenic (As) stress on rice (Oryza sativa L.) seedlings. Different concentrations of As (5, 10 and 15 ppm) and Bacillus subtilis synthesized Fe3O4 NPs solution (5, 10 and 15 ppm) alone and in combination were applied to rice seedlings. The results showed that As at 15 ppm significantly decreased the growth of rice, which was increased by the low level of As. Results indicated that B. subtilis synthesized Fe3O4 NP-treated plants showed maximum chlorophyll land protein content as compared with arsenic treatment alone. The antioxidant enzymes such as SOD, POD, CAT, MDA and APX and stress modulators (Glycine betain and proline) also showed decreased content in plants as compared with As stress. Subsequently, Bacillus subtilis synthesized Fe3O4 NPs reduced the stress associated parameters due to limited passage of arsenic inside the plant. Furthermore, reduction in H2O2 and MDA content confirmed that the addition of Bacillus subtilis synthesized Fe3O4 NPs under As stress protected rice seedlings against arsenic toxicity, hence enhanced growth was notice and it had beneficial effects on the plant. Results highlighted that Fe3O4 NPs protect rice seedlings against arsenic stress by reducing As accumulation, act as a nano adsorbent and restricting arsenic uptake in rice plants. Hence, our study confirms the significance of Bacillus subtilis synthesized Fe3O4 NPs in alleviating As toxicity in rice plants.

Zinc application promotes nitrogen transformation in rice rhizosphere soil by modifying microbial communities and gene expression levels

Application of Zn fertilizers to agricultural field is a simple and effective way for farmers to manage Zn deficient stress in soils to avoid yield lose. Although a synergistic effect of Zn on N transformation in soil has been reported, the mechanism is not fully understood yet. In this study, we planted rice in soils with different combinations of Zn and N supply, and analyzed the plant growth and N uptake, the N transformation, microbial communities, enzyme activities and gene expression levels in rhizosphere soil to reveal the underlying mechanism. Results showed that Zn application promoted the rice growth and N uptake, increased the soil alkali-hydrolyzed N and NH4+, but decreased NO3− and inhibited NH3 volatilization from the rhizosphere soil under optimal N condition. Zn supply significantly increased the relative abundances of Sphingomonas, Gaiella, subgroup_6, and Gemmatimonas, but decreased nitrosifying bacteria Ellin6067; while increased saprophytic fungi Schizothecium and Mortierella, but decreased pathogenic fungi Gaeumannomyces, Acremonium, Curvularia, and Fusarium in the rhizosphere soil under optimal N condition. Meanwhile, Zn application elevated the activities of protease, cellulase and dehydrogenase, and up-regulated the expression levels of napA, nirS, cnorB, and qnorB genes involved in the denitrification process in rice rhizosphere soil under optimal N condition. These results indicated Zn application could facilitate the soil N transformation and improved its availability by modifying both bacterial and fungal communities, and altering the soil enzyme activities and functional gene expression levels, ultimately promoted the N uptake and biomass of rice plant. However, this synergistic effect of Zn on rice growth, N uptake and soil N transformation strongly depended on the external N conditions, as no significant changes were observed under high N condition. Our results indicated that Zn co-fertilized with appropriate application of N is a useful strategy to improve the N bioavailability in rice rhizosphere soil and enhance the N uptake in rice plant.

Increasing phosphorus inhibits the retention and prevention of cadmium by iron plaque and promotes cadmium accumulation in rice plants

Iron (Fe) plaque is an important component of rice roots because it influences the uptake and transport of cadmium (Cd) in rice. In this study, a hydroponic experiment was developed to investigate the influence of phosphorus (P) on the formation of iron plaque on the root surface as well as the influence on Cd uptake in rice plants. Three important results were obtained, as follows. (1) During the formation of iron plaque induced by exogenous Fe, P supply was beneficial for the iron plaque formation, but it restrained the Cd retention capability, resulting in a decrease in Cd in iron plaque by 35.48–61.93%, and leading to an increase in Cd in rice roots from 72.13 mg kg−1 to 112.78 mg kg−1 (2) After the iron plaque induction, the formation of iron plaque was inhibited by P supply, resulting in the amount of iron plaque decreasing by 18.46–54.57%, and the Cd in iron plaque decreased by 3.93–31.78%. Then, the Cd retention capability and the prevention effect simultaneously decreased, and as a result, the Cd in rice roots increased from 100.83 mg kg−1 to 146.03 mg kg−1 (3) Without exogenous Fe induction, P sufficiency continued to increase the amount of iron plaque and decrease the Cd in iron plaque, and increase the Cd in rice plants. These results suggested that P supply increases the amount of iron plaque, which is ineffective for Cd retention, such as non-reddish-brown iron plaque (NIP), and then decreases the capacity of iron plaque to retain Cd. Additionally, the P supply decreased the amount of formed iron plaque, causing the decreasing prevention effect. Therefore, excessive application of P fertilizer should be avoided in Cd-contaminated paddy fields.

Co-Application of Biochar Compost and Inorganic Nitrogen Fertilizer Affects the Growth and Nitrogen Uptake by Lowland Rice in Northern Ghana

Inherent low soil fertility status limits productivity of rice in the lowland ecologies in Northern Ghana. Combining organic and inorganic nitrogen fertilizers could help to maintain the fertility of lowland soils for rice production. A screen house pot experiment was carried out to investigate the combined effect of biochar compost and inorganic nitrogen fertilizer on the nitrogen uptake and agronomic performance of rice plants grown on an eutric gleysol lowland soil. Inorganic nitrogen fertilizer alone and its combinations with different types of biochar compost (based on the proportions of biochar and compost) were used as treatment. A control (unamended soil) was also included. The incorporation of biochar compost and inorganic nitrogen fertilizer improved the growth parameters and yield components of rice plants. The combination of biochar compost and inorganic nitrogen fertilizer was also found to improve nitrogen uptake in rice plants. This practice could be the most likely viable option for alleviating lowland soil fertility issues and increasing rice productivity in Northern Ghana.

Essential Dynamics of Rice Cultivated under Intensification on Acid Sulfate Soils Ameliorated with Composted Oyster Mushroom Baglog Waste

This study examines the dynamics of essential macro-nutrients for rice cultivation in acid sulfate soils ameliorated with composted oyster mushroom baglog waste. A single factor randomized block design (RBD) was used, and the factors studied include the compost dose of oyster mushroom baglog waste, which consists of 5 treatment levels, namely 0 t ha-1 (control), 5 t ha-1, 10 t ha-1, 15 t ha-1, and 20 t ha-1. Furthermore, this study was carried out from May to September 2021 in the rice fields of the Faculty of Agriculture, Lambung Mangkurat University (ULM), Sungai Rangas Village, Banjar Regency, South Kalimantan. The rice plants were cultivated using an intensification technique, and the compost was applied based on the research treatment for two weeks on prepared land before planting. Also, Bartlett’s test was carried out before analysis of variance, which had a significant effect of P<0.05, and was further tested using Duncan’s Multiple Range Test (DMRT) at a 5% level. The results showed variations in the availability of macro-nutrients at five different growth stages: early planting, full vegetative, early panicle emergence, panicle filling, and harvesting phases. The highest levels of ammonium (NH4+) and nitrate (NH3-) were found in the full vegetative stage, while early planting had the lowest. Also, there was an increase in the available phosphorus (P) from the early planting to the full vegetative stage. The increase in exchangeable potassium (K) occurred at the transition of these stages. These increasing nutrients were due to the addition of the compost. The higher the NH4+, NO3-, available P, and exchangeable K in acid sulfate soils, the more nitrogen (N), P, and K uptake in rice plants. The provision of the compost supplied N, P, and K in available forms and reduced the amount of soluble alumunium (Al) and iron (Fe). Thereby the plant roots absorb the nutrients optimally. Additionally, the compost increased the essential macro-nutrient availability and plant uptake using the rice intensification technique from early planting to harvest.

Application of zinc oxide nanoparticles immobilizes the chromium uptake in rice plants by regulating the physiological, biochemical and cellular attributes.

Zinc oxide nano particles (ZnO NPs) have been employed as a novel strategy to regulate plant tolerance and alleviate heavy metal stress, but our scanty knowledge regarding the systematic role of ZnO NPs to ameliorate chromium (Cr) stress especially in rice necessitates an in-depth investigation. An experiment was performed to evaluate the effect of different concentrations of ZnO NPs (e.g., 0, 25, 50, 100mg/L) in ameliorating the Cr toxicity and accumulation in rice seedlings in hydroponic system. Our results demonstrated that Cr (100µM) severely inhibited the rice seedling growth, whereas exogenous treatment of ZnO NPs significantly alleviated Cr toxicity stress and promoted the plant growth. Moreover, application of ZnO NPs significantly augmented the germination energy, germination percentage, germination index, and vigor index. In addition, biomass accumulation, antioxidants (SOD, CAT, POD), nutrient acquisition (Zn, Fe) was also improved in ZnO NPs-treated plants, while the lipid peroxidation (MDA, H2O2), electrolyte leakage as well as Cr uptake and in-planta accumulation was significantly decreased. The burgeoning effects were more apparent at ZnO NPs (100mg/L) suggesting the optimum treatment to ameliorate Cr induced oxidative stress in rice plants. Furthermore, the treatment of ZnO NPs (100mg/L) reduced the level of endogenous abscisic acid (ABA) and stimulated the growth regulator hormones such as brassinosteroids (BRs) possibly linked with enhanced phytochelatins (PCs) levels. The ultrastructure analysis at cellular level of rice revealed that the application of 100mg/L ZnO NPs protected the chloroplast integrity and other cell organells via improvement in plant ionomics, antioxidant activities and down regulating Cr induced oxidative stress in rice plants. Conclusively,observations of the current study will be helpful in developing stratigies to decrease Cr contamination in food chain by employing ZnO NPs and to mitigate the drastic effects of Cr in plants for the sustainable crop growth.

Mathematical quantification of interactive complexity of transcription factors involved in proline-mediated regulative strategies in Oryza sativa under chromium stress

Involvement of transcription factor (TFs) in governing genes at transcription or post transcription level is known to have affirmative impact on plant physiological and morphological development, especially during environmental abuse. Application of exogenous proline (Pro) is one among the effective approaches to strengthen plant resistance against stresses. However, Pro-mediated regulative strategies of TFs in responses to the chromium (Cr) in rice plants through the gene interaction network are still not clear. In the current study, Pro-mediated interactive complexity of various TFs (i.e., MYB, NAC, WRKY, bHLH, and bZIP) under hexavalent chromium [Cr(VI)] was investigated using Agilent 4 × 44 K rice gene chip and gene interactive probability model (GIPM). Results showed that exogenous Pro had a negligible effect on Cr uptake in rice plants, while a small positive response in biomass accretion of rice seedlings was observed under Cr(VI)+Pro treatments which was to certain extend greater than single Cr(VI) treatments. Rice microarray analysis showed that Cr(VI) significantly (p < 0.05) repressed the expression of TFs in the rice roots and shoots, while the application of exogenous Pro significantly (p < 0.05) up-regulated the expression levels of some TFs in rice tissues. Mathematical modularization indicated that Pro-mediated interaction between MYB and NAC carried more weightage than other TFs in rice roots and shoots under Cr(VI) stress. Overall, our study provides convincing evidence to confirm a positive role of exogenous Pro on reducing the negative impact exerted by Cr(VI) on rice plants through regulating expression and interaction of different TFs.

Differences in uptake, utilization and loss of nitrogen and phosphorus in a Chinese double rice cropping system under different irrigation and fertilization managements

In order to optimize water and fertilizer use in the double-cropping rice in eastern Fujian Province, a field runoff plot experiment was conducted to investigate rice yield, nutrient uptake, and runoff losses of N (nitrogen) and P (phosphorus) in the T0(no chemical fertilization with traditional flooding irrigation), T1(common chemical fertilizer of 273 kg N·hm-2, 59 kg P·hm-2, and 112 kg K·hm-2 combined with traditional flooding irrigation), T2(chemical fertilizer of 240 kg N·hm-2, 52 kg P·hm-2, and 198 kg K·hm-2 combined with traditional flooding irrigation) and T3(chemical fertilizer combined with shallow intermittent irrigation) treatments. Results showed that early rice grain yield in the T1, T2 and T3 treatments significantly increased by 0.7, 1.0, 1.1 times, late rice grain yield significantly increased by 0.9, 1.1, 1.0 times compared to that in the T0 treatment, respectively. The T1, T2 and T3 treatments significantly increased the uptake of N and P in aboveground parts of the plants, especially in grains. The T1, T2 and T3 treatments significantly increased N uptake by 1.1, 1.2, 1.2 times, increased P uptake by 0.9, 1.4, 1.6 times in early-season grains, and significantly increased N uptake by 0.8, 1.0, 1.0 times, increased P uptake by 0.7, 0.9, 0.9 times in late-season grains, compared to T0, respectively. Furthermore, T3 increased agronomic N use efficiency (AEN) and agronomic P use efficiency (AEP) by 71.1% and 69.2% in early rice plants, increased AEN and AEP by 26.4% and 25.0% in late rice plants, whereas T3 decreased total dissolved N (DN) by 16.0% in comparison with T1. Dissolved inorganic N loss in surface runoff occurred mainly in the form of NO3--N (nitrate N) under different water and fertilizer regimes. However, there were no significant differences in AEN and AEP between T2 and T3 treatments. These findings suggested that optimal applications of water and fertilizers (T3) might increase N and P uptake in rice plants, maintain yield, and reduce N loss, especially in the form of NO3--N in surface water from early rice field. In general, this study could provide theoretical support for the optimization of irrigation and fertilization and for the control of N and P non-point source pollution from the double cropping rice paddy fields in eastern Fujian Province.

Influence of Manganese on Nutrient Uptake in Rice Plants under Saline Conditions

Salinity-induced nutritional disorders adversely affect the performance of crops. The consequence of salinity disorders may result on nutrient availability, competitive uptake, transport or partitioning within the plants. Present study was aimed to investigate the effects of Mn application on nutrient uptake contributing to the salinity tolerance of the rice. A hydroponic experiment was carried out in National Agriculture Research Centre, Islamabad, Pakistan, on two rice varieties. Three NaCl salt concentrations, namely 0, 25, 50 mmol were used. Manganese sulphate was used for foliar and root application with four concentrations (0, 2, 4, 8 mg Mn L-1). Salinity decreased the uptake of P, K, Ca, Mg, Mn and Zn in both applications methods while application of Mn increased the uptake of almost all the investigated macro and micronutrients. Root applications of Mn and foliar application methods were compared where root application method was found better for most of the nutrient uptake. Interaction effect i.e salinity × Mn treatment × methods of application was significant. The results showed that Mn application can improve the nutrient uptake capability contributing to the salinity tolerance in rice.

Bacillus tequilensis strain 'UPMRB9' improves biochemical attributes and nutrient accumulation in different rice varieties under salinity stress.

Soil salinity exert negative impacts on agricultural production and regarded as a crucial issue in global wetland rice production (Oryza sativa L.). Indigenous salt-tolerant plant growth-promoting rhizobacteria (Bacillus sp.) could be used for improving rice productivity under salinity stress. This study screened potential salt-tolerant plant growth-promoting rhizobacteria (PGPR) collected from coastal salt-affected rice cultivation areas under laboratory and glasshouse conditions. Furthermore, the impacts of these PGPRs were tested on biochemical attributes and nutrient contents in various rice varieties under salt stress. The two most promising PGPR strains, i.e., ‘UPMRB9’ (Bacillus tequilensis 10b) and ‘UPMRE6’ (Bacillus aryabhattai B8W22) were selected for glasshouse trial. Results indicated that ‘UPMRB9’ improved osmoprotectant properties, i.e., proline and total soluble sugar (TSS), antioxidant enzymes like superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Moreover, ‘UPMRB9’ inoculated rice plants accumulated higher amount of nitrogen and calcium in tissues. Therefore, the indigenous salt-tolerant PGPR strain ‘UPMRB9’ could be used as a potential bio-augmentor for improving biochemical attributes and nutrient uptake in rice plants under salinity stress. This study could serve as a preliminary basis for future large-scale trials under glasshouse and field conditions.

Effect of Fish Amino Acid Application on Growth and N-uptake in Plants Rice Using The System of Rice Intensification Method

Rice is the main rice crop which is used as the staple food of most Indonesians. Rice production in Indonesia cannot be separated from inorganic fertilizers which have a bad impact on the environment, so it is necessary to carry out a revolution, one of which is the SRI method. The addition of FAA organic matter originating from fish sorted by fishermen which have no selling price is used as a substitute for inorganic fertilizers. This study aims to determine the effect of FAA application on growth and N uptake in rice plants using the SRI method and to determine the best dose of the effect of FAA application on growth and N uptake in rice plants using the SRI method. This research was conducted in December 2019 - April 2020 at the Greenhouse of the Agroecotechnology Department, Faculty of Agriculture, Lambung Mangkurat University, Banjarbaru. The design used was a one-factor Completely Randomized Design (CRD), with treatment f0 (control / without FAA application), f1 (1 mL FAA / L), f2 (3 mL FAA / L), f3 (5 mL FAA / L) , and f4 (7 mL FAA / L). The treatment was repeated 5 times, to obtain 25 experimental units. Observation parameters in the study were plant height, number of tillers, and N uptake of rice leaves. The results showed that the application of FAA with a dose of 1 mL FAA / L was able to increase the height of rice plants by 5.5%, produced an average number of tillers of 14 tillers, and was able to increase nitrogen uptake by 9.6% in rice plant leaves.