Potassium Absorption Research Articles

Effects of Potassium Application on Growth and Root Metabolism of Salvia miltiorrhiza under Drought Stress

Potassium application can effectively mitigate the effects of drought stress on plant growth, and few studies have reported its application to the medicinal plant Salvia miltiorrhiza (S. miltiorrhiza). Four experimental treatments were used, including a control (Z1K0), non-drought potassium application (Z1K3), drought treatments (Z2K0), and drought-stress potassium application (Z2K3). The findings revealed that, in contrast to Z2K0, Z2K3 promoted the absorption of potassium in S. miltiorrhiza, elicited the aggregation of osmoregulatory compounds such as soluble protein and proline, and mitigated membrane impairment as a defense against the deleterious consequences of drought stress. Additionally, we extended our investigation to encompass comprehensive metabolomics analysis of the roots. Interestingly, subsequent root metabolomics analyses demonstrated that the drought application of potassium not only significantly reduced the amino acid content, but also increased the amount of terpenoids and phenolic acids in the roots. Nonetheless, the application of a particular amount of K under moderate drought conditions promoted the growth and yield of S. miltiorrhiza, but proved to be detrimental to its active ingredients. Indeed, the findings of this study offer valuable insights and recommendations for the application of potassium to mitigate the impact of drought stress in S. miltiorrhiza and other medicinal plants.

Exogenous γ-aminobutyric acid improves the photosynthesis efficiency, soluble sugar contents, and mineral nutrients in pomegranate plants exposed to drought, salinity, and drought-salinity stresses

Backgroundγ-aminobutyric acid (GABA), as a regulator of many aspects of plant growth, has a pivotal role in improving plant stress resistance. However, few studies have focused on the use of GABA in increasing plants’ resistance to interactional stresses, such as drought-salinity. Therefore, the focus of this study was to examine the effect of foliar application of GABA (0, 10, 20, and 40 mM) on growth indices and physio-biochemical parameters in plants of two pomegranate cultivars, ‘Rabab’ and ‘Atabaki’ exposed to drought, salinity, and drought-salinity.ResultsUnder stress conditions, the photosynthetic capacity of two pomegranate cultivars, including transpiration rate, net photosynthetic rate, intercellular carbon dioxide concentration, stomatal conductance of water vapour, and mesophyll conductance, was significantly reduced. This resulted in a decrease in root morphological traits such as fresh and dry weight, diameter, and volume, as well as the fresh and dry weight of the aerial part of the plants. However, the application of GABA reversed the negative effects caused by stress treatments on growth parameters and maintained the photosynthetic capacity. GABA application has induced the accumulation of compatible osmolytes, including total soluble carbohydrate, starch, glucose, fructose, and sucrose, in charge of providing energy for cellular defense response against abiotic stresses. Analysis of mineral nutrients has shown that GABA application increases the absorption of potassium, potassium/sodium, magnesium, phosphorus, manganese, zinc, and iron. As concentration increased up to 40 mM, GABA prevented the uptake of toxic ions, sodium and chloride.ConclusionsThese findings highlight the potential of GABA as a biostimulant strategy to enhance plant stress tolerance.

Soil Potassium Balance in the Hilly Region of Central Sichuan, China, Based on Crop Distribution

The problem of soil fertility imbalance in hilly agriculture is prominent, and accurate estimation of soil potassium balance is key to achieving precision fertilization at the regional level. Crop distribution has a significant impact on potassium balance, but studies on potassium balance with a focus on crop cultivation types are scarce, especially with regard to hilly areas. In this study, the spatial distribution characteristics of soil potassium balance under different cropping conditions and its influencing factors were analyzed for a hilly region. The results showed that (1) the soil rapidly available potassium (RAK) and slowly available potassium (SAK) content in the 0–20 cm soil layer ranged from 29.37 to 122.07 mg kg−1 and from 472.31 to 772.77 mg kg−1, respectively. (2) The soil potassium equilibrium status varied considerably among different cropping systems and the soil potassium deficit was greatest under the rapeseed–maize rotation, reaching −129.50 kg K ha−1 yr−1. The difference in soil potassium deficits between the rice–rapeseed and wheat–maize rotations was not significant, at −46.79 kg K ha−1 yr−1 and −44.07 kg K ha−1 yr−1, respectively, and only the rice–wheat rotation showed a potassium surplus. Due to the low potassium absorption of crops, the equilibrium value of soil potassium is higher than that of crop rotation, and rice and wheat can achieve different degrees of potassium surplus. Rapeseed planting was generally under-applied with potassium, and the potassium deficit could reach −70 kg K ha−1 yr−1. (3) Climate, topography, anthropogenic activity, and soil available potassium explained 20.8% of the variance in soil potassium balance. Anthropogenic activity such as roads and population density had the greatest influence, with 0.797. Topography and average annual precipitation had the weakest influences. These findings emphasize the importance of anthropogenic activity for soil potassium balance, and also provide regional evidence for formulating efficient measures for regional potassium resources management.

Dynamics of the Content of Nutrients in Agrochernozem during the Cultivation of Ginger Seed

In the field experiment, the food regime of agrochernozem was studied during the cultivation of the seed ginger (Camelina sativa (L.) Crantz) in the conditions of the Kansk forest-steppe of the Krasnoyarsk Territory. The predominant absorption and removal of nitrate nitrogen and exchangeable potassium by the culture determined the low availability of 0–40 cm of mineral nitrogen in the soil layer (5–6 mg/kg) while maintaining an average and very high availability of exchangeable potassium (87–158 mg/kg). It is shown that the largest share of the return to the soil after harvesting the ginger was accounted for by N and P (50–37%). With root and crop residues, nitrogen – 70, phosphorus – 19 and potassium – 51 kg/ha were returned to the soil. Agrochernozems of the Kansk forest-steppe, without additional fertilization, are able to provide a sufficient level of phosphorus and potassium nutrition in ginger crops.

Effect of Arranger of Conductor Tubes of Adjusted Subsurface Drip Irrigation (SSDIadj) on Potassium Absorption and Pistachio Yield at Damghan Region

Effect of Arranger of Conductor Tubes of Adjusted Subsurface Drip Irrigation (SSDIadj) on Potassium Absorption and Pistachio Yield at Damghan Region

Trichoderma longibrachiatum Inoculation Improves Drought Resistance and Growth of Pinus massoniana Seedlings through Regulating Physiological Responses and Soil Microbial Community.

Drought stress poses a serious threat to Pinus massoniana seedling growth in southern China. Trichoderma species, as beneficial microorganisms, have been widely used in agriculture to enhance plant growth and drought tolerance, but the interaction mechanisms remain unclear. To investigate the effect of drought-resistant Trichoderma longibrachiatum inoculation on P. massoniana growth under drought stress, the plant physiological indicators and rhizosphere microbiome diversity were measured to identify Trichoderma-activated mechanisms. Trichoderma longibrachiatum inoculation significantly promoted P. massoniana growth under drought treatment, and enhanced nitrogen, phosphorus, and potassium absorption compared with those of non-inoculated seedlings. Trichoderma longibrachiatum treatment alleviated the damage to cell membranes and needle tissue structure, and significantly increased antioxidant enzyme activities, osmotic substance contents, and photosynthesis in P. massoniana in response to drought stress. Soil nutrient contents, activities of sucrase, phosphatase, and urease as well as the relative abundances of the dominant genera Burkholderia, Rhodanobacter, and Trichoderma were elevated in the rhizosphere soil of P. massoniana inoculated with T. longibrachiatum under drought stress. A network analysis showed that certain crucial dominant taxa driven by T. longibrachiatum inoculation, including Penicillium, Trichoderma, Simplicillium, Saitozyma, Burkholderia, Bradyrhizobium, Sinomonas, and Mycobacterium, had more correlations with other microorganisms in the soil. Trichoderma longibrachiatum enhanced P. massoniana seedling growth under drought stress by regulating physiological responses and soil microbial community.

节水灌溉与调理剂结合对旱直播稻产量、养分吸收及品质影响

Dry direct seeding cultivation technology of rice is an important aspect of rice production and management. Six treatments were designed in this paper, and that is, T1 (conventional irrigation), T2 (conventional irrigation + conditioner), T3 (30% water-saving irrigation), T4 (30% water-saving irrigation + conditioner), T5 (50% water-saving irrigation), T6 (50% water-saving irrigation + conditioner). The results showed that in the three separate irrigation treatments, 30% water-saving irrigation was conducive to the growth of dry direct seeding rice at the tillering stage, jointing and booting stage, and 50% water-saving irrigation was more conducive to the growth of rice at grain filling stage. Compared with no application of amendments, all kinds of treatments could significantly promote the growth of dry direct seeding rice. Under the condition of water-saving irrigation of 30%, higher dry matter quality, yield and nutrient absorption can be obtained. The total dry matter quality and rice yield of T4 treatment with 30% water-saving irrigation and conditioner were the highest, which were 99.90 g/pot and 37.76 g/pot respectively, compared with conventional treatment (T1) was 37.60% and 45.96% higher, and this treatment had obvious effect on nitrogen and potassium absorption. In terms of quality impact, water saving was 30% Irrigation conditions are conducive to the improvement of rice processing quality, appearance quality and nutritional quality, especially after the application of conditioner, the overall rice quality is improved. This study has a certain reference value for water-saving irrigation, promoting nutrient utilization, stable yield and high quality of dry direct seeding rice.

Isolation and identification of highly effective potassiumsolubilising bacterial strain from coastal soils

Soil potassium supplementation relies heavily on the use of chemical fertilizer, which has a considerablenegative impact on the environment. Potassium-solubilizing bacteria (KSB) could serve as inoculants.They convert insoluble potassium in the soil into a form that plants can access. This is a promising strat-egy for the improvement of plant absorption of potassium and so reducing the use of chemical fertilizer. In order to overcome poor potassium availability, potassium solubilising microorganisms can be used to ensure agriculture production. Hence, the study was aimed to isolate, identify, and characterise a potent bacterial species from coastal soils that can efficiently solubilise phosphate for plant absorption. From the five soil samples, a total of eight different discrete bacterial colonies were identified and they were named as MGK-01, MGK-02, MGK-03, MGK-04, MGK-05, MGK-06, MGK-07 and MGK-08. The screening of potassium solubilisation demonstrates that the greatest potassium solubilisation ability was found in the MGK-06 strain. Furthermore, the greatest potassium solubilisation under increasing NaCl concentrations were found in the MGK-06. Due to better potassium solubility and plant growth promoting activities, bacterial isolate MGK-06 was selected for molecular identification and bioinoculation studies. The molecular phylogeny revealed that the bacterial isolate MGK-06 is belongs to Azotobacter chrococcumspecies.

Root zone temperature regulates potassium absorption and photosynthesis in maize (Zea mays)

Affected by climate warming, the impact of crop root zone warming (RZW) on maize seedling growth and nutrient uptake deserve attention. The characteristics of K uptake in maize under root zone warming and the combined impacts of potassium deficiency and RZW are still unclear. The present study aimed to investigate the effects of RZW on potassium absorption and photosynthesis of maize seedlings under the difference in potassium. The results showed that RZW and low potassium treatment significantly affected root shoot development and photosynthetic physiological characteristics of maize seedlings. Moreover, the interaction of RZW and potassium content had striking influence on maize seedlings. Under the normal potassium with root zone medium temperature treatment, the development of maize was the most vigorous. Under the dual stress of high root zone temperature and low potassium, the root absorption area, total potassium content and root activity were significantly reduced, which then influenced the light energy use efficiency and dry matter accumulation. Securing the supply of potassium fertilizer under high root zone temperature stress is useful to alleviate the impact of high temperature stress.

Evaluation of Soil Salinity Using Inductively Coupled Plasma-Mass Spectrometer (ICBMS)--Case Study of Al Qassim Region, Kingdom Saudi

Al Qassim region situated in the middle of the Kingdom of Saudi Arabia. It has a population of roughly 370,727 people and a 58,046-km² area. It is referred to as the "trophic basket" of the nation due to its agricultural resources. It is one of Saudi Arabia's most significant agricultural districts. Soil salinization is present as a global problem. Analyzing the impact of trace elements on soil salinization done. The concentrations of trace elements in three samples (Chlorine (Cl), Sodium (Na), Potassium (K), Magnesium (Mg), and Boron (B),), were taken from the western and eastern sides and 50cm depth, were testing using a COUPLED PLASMA-MASS SPECTROMETER (ICBMS), and they were found to be (152 μg/g, 5066 μg/g, 16022 μg/g, 4.2 μg/g, respectively) for the first sample. (185 μg/g, 4873 μg/g, 14876 μg/g, 2.6 μg/g, and respectively) for the second sample. (144μg/g, 5298 μg/g, 15080 μg/g, 3.8 μg/g, respectively) for the third sample. A pH meter used to determine the pH. The pH ranged from 5.98 on the east to 6.08 and 6.02 for 50cm depth, indicating somewhat acidic conditions. In addition, the concentrations of SO₄ and HCO₃, salty water-containing anions, which are common components, were tested. One of the main barriers to plant growth and development in acidic soils is aluminum (Al) toxicity. Magnesium and potassium values are higher than usual. At the plant root, a high potassium concentration prevents magnesium from being absorbed; a high magnesium content in the soil solution has no effect on potassium absorption.

Potassium capture by ilmenite ore as the bed material during fluidized bed conversion

Biomass is a complex fuel containing a heterogeneous mixture of organic matter and, to a lesser extent, inorganic matter. Inorganic ash-forming elements can cause serious ash-related problems in fluidized bed combustion systems, such as bed agglomeration, fouling and corrosion of heat transfer equipment. Potassium (K), a biomass ash component, is a major contributor to these phenomena. The aim of this work, in the context of high-potassium biomass fuel combustion, is to estimate the potential for the absorption of potassium by bed materials under different oxygen carrier aided combustion (OCAC) operating conditions, in terms of reaction gas composition, exposure duration, bed temperature, potassium salt type, and concentrations of potassium salt. Experiments were conducted with an electrically heated fluidized bed reactor (FBR). The potassium solution is injected into the dense bed region via a small tube. In the studied temperature range of 700–900 °C, the captured K amount increases significantly at temperatures lower than 850 °C. The gas atmosphere had a less notable effect on K capture, but the capture rate of potassium dropped to half after the K-solution was switched from KOH to K2CO3 in the CO2 gas atmosphere. The percentage of injected potassium that is captured is high (∼40–60 wt%) in the first 5 h, and it remains at a high level of about 35 wt% after 25 h. KTi8O16 is the only crystalline K-compound found in the bed solid samples when ilmenite ore was used as bed material. KAlSi3O8 and K0.43(NH4)0.53Al0.89Si2.11O6 were detected when olivine sand was used as bed material. Thermogravimetric analysis (TGA) indicated no significant effect of the spent ilmenite on its redox reactivity after its reaction with K-solutions in the fluidized bed; however, the O2-carrying capacity of spent ilmenite shows a 7 % reduction after 25 h of exposure to potassium in the fluidized bed.

Industrial Organic Wastewater through Drip Irrigation to Reduce Chemical Fertilizer Input and Increase Use Efficiency by Promoting N and P Absorption of Cotton in Arid Areas

The use of industrial waste as an agricultural resource is important for clean and sustainable agriculture. We assumed that industrial organic wastewater coupled with chemical fertilizer would increase cotton yield by enhancing nutrients absorption and utilization. To test this hypothesis, a two-year (2019–2020) field trial was conducted to assess the impacts of CK (0 kg ha−1), chemical fertilizer (CF) (N-P2O5-K2O: 228-131-95 kg ha−1), chemical fertilizer + organic wastewater (F0.6 (60%CF + OW: 1329 kg ha−1), F0.8 (80%CF + OW), F1.0 (CF + OW), F1.2 (120%CF + OW) and F1.4 (140%CF + OW)) on nutrient absorption and distribution, fertilizer use efficiency and cotton yield under drip irrigation system. Compared with CF, the soil organic matter, NH4+-N and AV-K increased significantly after F0.8-F1.4 treatments. The absorption of nitrogen (N), phosphorus (P) and potassium (K) by plants after dripping organic wastewater (F0.8-F1.4) increased by 1.1–11.2% as compared with CF (F0.6, CF < F0.8, F1.0 < F1.2, F1.4). Under F0.8, treatment resulted in a higher distribution rate of N, P and K in reproductive organs compared with other counterparts. In addition, drip application of organic wastewater promoted the absorption of magnesium (Mg) and zinc (Zn) in leaves and Fe in roots with higher translocation of Zn and boron (B) to reproductive organs compared with other treatments. The absorption of N, P and K was positively correlated with Mg, negatively correlated with calcium (Ca) and sulfur (S), and positively correlated with manganese (Mn) and iron (Fe). The yield and fertilizer utilization rate of cotton were higher at F0.8. Conclusively, the use of 1329 kg ha−1 organic wastewater (organic mattered ≥ 20%, humic acid ≥ 20 g L−1, Bacillus subtilis ≥ 2 × 108 L−1) combined with chemical fertilizer (N-P2O5-K2O) at (182-104-76 kg ha−1) reduces the application of chemical fertilizer and can increase utilization efficiency of chemical fertilizer with a high cotton yield under mulch drip irrigation in arid regions.

Steroidal or non-steroidal MRAs: should we still enable RAASi use through K binders?

Renin-angiotensin-aldosterone system inhibitors (RAASi) and mineralocorticoid receptor antagonists (MRAs) are important interventions to improve outcomes in patients with chronic kidney disease and heart failure, but their use is limited in some patients by the development of hyperkalemia. The risk of hyperkalemia may differ between agents, with one trial showing lower risk of hyperkalemia with the novel non-steroidal MRA finerenone compared with steroidal MRA spironolactone. Novel potassium binders, including patiromer and sodium zirconium cyclosilicate, are available interventions to manage hyperkalemia and enable continuation of RAASi and MRAs in patients who could benefit from these treatments. These agents bind free potassium ions in the lumen of the gastrointestinal tract to prevent the absorption of dietary potassium and increase potassium secretion. Several studies showed that potassium binders are effective compared with placebo for preventing hyperkalemia or steroidal MRA discontinuation, but none has evaluated whether this strategy impacts clinically important endpoints such as cardiovascular events. Due to this and other limitations related to cost, clinical availability, pill burden and patient selection, alternative potential strategies to mitigate hyperkalemia may be more practical. Conservative strategies include increased monitoring and use of loop or thiazide diuretics to increase urinary potassium excretion. Non-steroidal MRAs may have a lower risk of hyperkalemia than steroidal MRAs and have stronger anti-inflammatory and anti-fibrotic effects with resultant reduced risk of kidney disease progression. Sodium-glucose cotransporter-2 inhibitors also decrease hyperkalemia risk in patients on MRAs and decrease cardiovascular events and kidney disease progression. These may be better first-line interventions to obviate the need for potassium binders and offer additional benefits.

Inoculation of Arbuscular Mycorrhizal Fungi Isolated from Peach Orchards and Vineyards in Aldrighi Peach Rootstock Plants

Arbuscular mycorrhizal fungi species (AMFs) present intraspecific differences in the ability to stimulate plant growth and depend on genetic and environmental factors involved among the biotic agents. This work aimed to evaluate the influence of the AMFs Glomus clarum and G. etunicatum isolated from peach orchards and vineyard on the vegetative growth, content of nutrients and carbohidrate contents on Aldrighi peach rootstocks plants. The experiment was conducted in a greenhouse, with a split-plot experiment, with 15 plants per plots and four repetitions. The plants inoculated with AMFs had higher responses in height, diameter, leaf area, fresh and dry biomass of shoots and content of reserves, due to the increased absorption of nitrogen, phosphorus and potassium in excess of non-inoculated plants. Data were submitted to analysis of variance using the Statistical Analysis System (SAS) program and the means were compared using Duncan's test at a 5% significance level. Simple correlation analyzes were performed using Pearson's correlation coefficient (r) with maximum values represented by r = 1 and r = -1. All AMF isolates benefited the Aldrighi peach rootstock plants, accelerating vegetative development and increasing macronutrient content. The study showed a correlation between root colonization and the increase in plant development parameters. The symbiosis efficiency was higher with isolates from peach orchards, when compared with isolates from grapevine orchards.

Impact of polyethylene on soil physicochemical properties and characteristics of sweet potato growth and polyethylene absorption.

Microplastic (MP) pollution problem is severe in China. As the main component of mulch film, whether polyethylene (PE) poses a threat to the safe production of sweet potato is unknown. In this study, micron-sized original or weathered PE was simulated as the field film particles, and pot, hydroponic experiment were conducted to explore the effects of original and weathered MPs on physicochemical properties in soil, growth and phosphorus (P), potassium (K) absorption in sweet potato; P and K adsorption in liquid environment, and also the distribution of original MPs in sweet potato tissues respectively. The results showed that 5μm original PE MPs significantly reduced pH (5.6-7.9%) and increased EC (6.0-12.1%) of soil compared to weathered PE MPs. In addition, original PE MPs can also significantly improved the biomass growth rates (5.9-19.0%) of sweet potato compared with weathered PE MPs by adsorbing more Olsen-P and Olsen-K in soil, and increasing K concentration in stems compared with control (17.1-55.4%). Although there was no significant difference between original and weathered PE MPs on the degree of membrane lipid peroxidation in sweet potato leaves, the original PE MPs made sweet potato exhibit the stronger oxidative stress. The tissue distribution of PE MPs-fluorescent spheres were only observed in cortical tissues of roots and stems. Results from our study suggest that sweet potato were not significantly affected by a short term exposure to single PE MPs.

Quantifying source-sink relationships of drip-fertigated potato under various water and potassium supplies

Water and fertilizer supply can affect the processes of assimilate production (source) and assimilate accumulation (sink), thereby causing differences in potato yield. However, little is known about the coupling effects of irrigation amount and potassium rate on potato tuber yield and its potential source-sink relationships. The objective of this study was to quantify how water and potassium supplies affected the source-sink relationships of drip-fertigated potato after tuber emergence. A two-year field experiment was conducted during the potato growing seasons of 2019 and 2020, with three irrigation levels (W1: 60% ET c , W2: 80% ET c and W3: 100% ET c , where ET c is the crop water requirements) and four potassium rates (K0: 0 kg ha -1 , K1: 135 kg ha -1 , K2: 270 kg ha -1 and K3: 405 kg ha -1 ). The results showed that compared with K0, the treatments viz ., K1, K2 and K3 increased average tuber yield by 1.3%, 17.3% and 15.5% in 2019 and 10.7%, 24.0% and 19.3% in 2020, respectively. However, compared with W3, the treatments viz ., W1 and W2 reduced the average tuber yield by 8.0% and 12.9% in 2019 and 8.9% and 14.7% in 2020, respectively. The beta sigmoid growth function well fitted the relationship of source capacity and sink capacity. The source capacity and source activity increased with the increase of potassium rate under W2 and W3 in 2019 and under W3 in 2020, while the sink capacity and sink activity first increased and then declined with the increasing potassium rate. Increasing water and potassium supply generally increased the vegetative growth and tuber growth time. The tuber growth rate first increased and then decreased with the increase of potassium rate, while it increased with the increasing irrigation amount. The sink-source ratio decreased with the increase of potassium rate, but there was no significant difference between K1 and K2, and the sink-source ratio under K3 was significantly lower than that in the other potassium treatments. It was concluded that potato was in source-sink balance under K1 and K2, but not under K3. The quantitative approach produced parameters that characterized the differences of source and sink capacity in response to various water and potassium supplies. Sufficient irrigation (W3) with moderate potassium application (K2) increased potato yield mainly by maintaining its source-sink balance. • A model approach was proposed to quantify source-sink relationships of potato under various water and potassium supplies. • The mechanism analysis of yield difference from various water and potassium supplies was conducted by source-sink balance. • Source-sink capacity was affected by different water and potassium management practices. • The sink-source ratio was not significantly different between 135 and 270 kg ha -1 , indicating the source-sink balance. • Various water and potassium application amounts influenced plant potassium absorption and tuber yield.

Combined analysis of mRNA and miRNA reveals the banana potassium absorption regulatory network and validation of miRNA160a.

Potassium (K) has an important effect on the growth and development of plants. Banana contains higher K content than many other fruits, and its plant requires more K nutrient in soil. However, the soil in the banana-producing areas in China is generally deficient in K. Therefore, understanding the mechanism of banana K absorption may assist in providing effective strategy to solve this problem. This study used two banana varieties with contrasting K tolerance, 'Guijiao No. 1' (low-K tolerant), and 'Brazilian banana' (low-K sensitive)to investigate K absorption mechanisms in response to low-K stress through miRNA and mRNA sequencing analysis. Under low-K condition, 'Guijiao No.1' showed higher plant height, dry weight, tissue K content and ATPase activity. Analysis of transcription factors showed that they were mainly in the types or classes of MYB, AP-EREBP, bHLH, etc. The sequencing results showed that 'Guijiao No. 1' had 776 differentially expressed genes (DEGs) and 27 differentially expressed miRNAs (DEMs), and 'Brazilian banana' had 71 DEGs and 14 DEMs between normal and low K treatments. RT-qPCR results showed that all miRNAs and mRNAs showed similar expression patterns with RNA-Seq and transcriptome. miRNA regulatory network was constructed by integrated analysis of miRNA-mRNA data. miR160a was screened out as a key miRNA, and preliminary functional validation was performed. Arabidopsis overexpressing miR160a showed reduced tolerance to low K, and inhibited phenotypic traits such as shorter root length, and reduced K accumulation. The overexpressed miR160a had a targeting relationship with ARF10 and ARF16 in Arabidopsis. These results indicate that miR160a may regulate K absorption in bananas through the auxin pathway. This study provides a theoretical basis for further study on the molecular mechanism of banana response to low potassium stress.

Nitrogen Reduction Combined with Organic Materials Can Stabilize Crop Yield and Soil Nutrients in Winter Rapeseed and Maize Rotation in Yellow Soil

Objective: To investigate the effect of nitrogen reduction combined with organic materials on crop growth of winter rapeseed and maize rotation in yellow soil. Methods: A 2-year, four-season winter rapeseed and maize rotation experiment using three organic materials (biochar (B), commercial organic fertilizer (O) and straw (S), 3000 kg·hm−2) and three nitrogen application rates (100%, 85% and 70%) was carried out from 2018 to 2020 in Guizhou Province, China. By comprehensively analyzing the crop yield, biomass and nutrient absorption, soil nutrients indicators, and the efficiency of nitrogen fertilizer was calculated. Results: All organic materials could increase the yield of both crops, and 100% N + O treatment was the best, and the 2-year winter rapeseed and maize yields reached 3069 kg·hm−2, 3215 kg·hm−2 and 11,802 kg·hm−2, 11,912 kg·hm−2, respectively. When nitrogen application was reduced by 15%, the addition of the three organic materials could stabilize or increase the yield and biomass, and nitrogen, phosphorus and potassium absorption in both crops showed an increasing trend, which could improve or maintain soil nutrients. When nitrogen application was reduced by 30%, the yields of two crops with organic materials addition were lower than those of 100% N treatment. Through the interaction, it was found that nitrogen and organic material were the main reasons for the increase in yield, respectively. Conclusions: The addition of three organic materials can replace 15% of nitrogen fertilizer. It is recommended to apply 153.0 kg·hm−2 and 127.5 kg·hm−2 of nitrogen fertilizer in winter rapeseed and maize seasons, respectively, in the rotation area of Guizhou yellow soil, with the addition of 3000 kg·hm−2 organic materials, most appropriately commercial organic fertilizer.

Effects of nutrient uptake and utilization on yield of maize-legume strip intercropping system

<p id="C2">To clarify the difference of nutrient uptake and utilization to yield advantage between maize-soybean relay intercropping and maize-peanut intercropping, we conducted a field experiment for two consecutive years. The results were obtained by comparing nitrogen (N), phosphorous (P), and potassium (K) absorption efficiency and utilization in the intercropping with sole cropping. The results showed that land equivalent ratio (LER) of maize-soybean relay intercropping was 1.16-1.72, which had the advantage of intercropping yield, but the LER of maize-peanut intercropping was 0.89-1.13, which had no obvious yield disadvantage. In maize-soybean relay intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by 32.60%-54.22%, 27.35%-34.64, and 17.74%-24.42%, respectively, but the N utilization efficiency was lower by 21.99%-42.07%. The contributions of the N, P, and K uptake efficiencies to LER were 0.34-0.62, 0.31-0.46, and 0.22-0.32, and the utilization efficiencies contributions were -0.11 to -0.35, -0.03 to -0.31, and -0.11 to 0.22, respectively. In maize-peanut intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by -7.86% to 31.58%, 23.09%-46.52%, and 1.60%-55.48%, respectively, and the N utilization efficiency was higher by 7.55-26.60. The contributions of the N, P and K uptake efficiencies to LER were 0-0.22, 0.05-0.27, and -0.11-0.32, respectively, and the utilization efficiencies contributions were -0.25-0.19, -0.32-0.11, and -0.47-0.32, respectively. In conclusion, yield advantage of maize-soybean relay intercropping was mainly from enhanced nutrient uptake efficiency, but there was no obvious yield advantage in maize-peanut intercropping mainly due to relatively less contribution of nutrient uptake to yield advantage.

Effect of Enerplant® doses on the development and nutrient use by cacao (Theobroma cacao L.) seedlings

Objective: To evaluate the effect of the application of biostimulant doses on the development, absorption, and use efficiency of nitrogen, phosphorus, and potassium by cacao seedlings. Design/Methodology/Approach: Five doses of Enerplant® (0, 1, 2, 3, and 4 mL ha-1) were applied to cacao seedlings grown under a saran mesh. The study was carried out using a completely randomized design. The foliar area received a monthly application of the biostimulant. In order to determine the nutrient absorption, 3 plants per treatment were divided into leaves, stems, and roots; they were subsequently dried for 72 h at 65 °C. Finally, they were ground, packaged, labeled, and sent to the laboratory, where the macronutrients of each component were analyzed. Results: The cacao seedlings had a positive response to the biostimulant application. In average, the results of our two-year study were: 1 mL ha-1 doses of Enerplant® significantly increased height (24%), dry mass (30%), quality index (58%), and foliar area (56%) of the cacao seedlings. Doses higher than 1- and 2-mL ha-1 decreased plant growth. The nutrient absorption by cacao in the nursery stage followed the following pattern: K &gt; N &gt; P. Findings/Conclusions: The efficiency of nutrient use —regardless of the Enerplant® dose applied— was higher for P, followed by N and, finally, K. Applying 2 mL ha-1 doses of the biostimulant guaranteed the highest absorption and use efficiency values of macronutrients by cacao seedlings.