Potassium Application Research Articles

Effect of Different Fertilization Treatments on Methane and Nitrous Oxide Emissions from Rice-Vegetable Rotation in a Tropical Region, China

The study of the effects of different fertilization treatments on soil methane (CH4) and nitrous oxide (N2O) emissions in rice-vegetable rotation systems is of great significance to supplement the research gap on greenhouse gas emissions in tropical regions of China. In this study, four fertilization treatments were set up during the pepper season:phosphorus and potassium fertilizer application (PK); nitrogen, phosphorus, and potassium (NPK) application; half application of nitrogen, phosphorus, and potassium plus half application of organic fertilizer (NPK+M); and application of organic fertilizer (M). There was no fertilizer application during the following early rice season. The objective of our study was to investigate the rules of CH4 and N2O emissions under different fertilization treatments in the pepper growth season, and the effects of different fertilization treatments in the pepper growth season on rice yield, and CH4 and N2O emissions in the following early rice growth season. The close static chamber-gas chromatography method was applied to determine soil CH4 and N2O emissions. We measured crop yield, estimated global warming potential (GWP), and calculated greenhouse gas emission intensity (GHGI). Our results showed that:① the cumulative CH4 emission under the four fertilization treatments ranged between 0.9 kg·hm-2 to 2.7 kg·hm-2 during the pepper growth season and between 5.5 kg·hm-2 to 8.4 kg·hm-2 during the early rice growth season. Compared with NPK, NPK+M and M reduced the cumulative CH4 emission in the pepper growth season by 35.3% and 7.6%, respectively; however, NPK+M and M increased the cumulative CH4 emission in the early rice season by 37.5% and 55.1%, respectively. There was a significant difference in cumulative CH4 emission between M and NPK in the early rice growth season. ② The cumulative N2O emission under the four fertilization treatments varied from 0.5 kg·hm-2 to 3.0 kg·hm-2 in the pepper growth season and from 0.3 kg·hm-2 to 0.5 kg·hm-2 in the early rice growth season. The cumulative N2O emission was significantly decreased by 33.7% in NPK+M and by 16.0% in M, compared with that in NPK. In the early rice growth season, the cumulative N2O emission was decreased by 23.5% by NPK+M but was increased by 9.1% by M. There was no significant difference in the cumulative N2O emission among the four fertilization treatments. ③ The yields of pepper and early rice under the four fertilization treatments were 3055.6-37722.5 kg·hm-2 and 5850.9-6994.4 kg·hm-2, respectively. Compared with that in NPK, NPK+M and M significantly increased pepper yield. The GWP under the four fertilization treatments in the pepper-early rice rotation system varied from 508.0 kg·hm-2 to 1864.4 kg·hm-2. Compared with NPK, NPK+M significantly decreased GWP by 25.7% and M insignificantly decreased GWP by 5.7%. The pepper growth season with the four fertilization treatments contributed to 69.2%-78.1% of the total GWP, and N2O contributed to 77.3%-85.3% of the total GWP. The GHGI ranged between 0.03 kg·kg-1 and 0.09 kg·kg-1 in the pepper growth season and between 0.04 kg·kg-1 and 0.24 kg·kg-1 in the early rice growth season. Compared with that in NPK, both M and NPK+M significantly reduced the GHGI by 71.5% and 54.7%, respectively, in the pepper growth season. In the early rice season, NPK+M significantly decreased the GHGI by 44.0%, but M non-significantly decreased the GHGI by 20.8%. The peak in N2O emission in the tropical pepper-early rice rotation system appeared after fertilization, and N2O emissions primarily occurred in the pepper growth season. However, CH4 emission was mainly concentrated in the early rice season. Considering the overall enhancing effects on crop yield and mitigation of greenhouse gas emissions, the co-application of chemical and organic fertilizers (NPK+M) can be recommended as an optimal fertilization practice to mitigate greenhouse gas emissions and maintain crop yield in pepper-rice rotation systems of Hainan, China.

Application of Potassium after Waterlogging Improves Quality and Productivity of Soybean Seeds.

Potassium (K) improves the stress tolerance of crop plants, which varies on the timing of K application and crop varieties. Soybean is a promising crop that can easily fit with the cropping pattern during kharif I season, when water logging occurs due to sudden rain. Therefore, an experiment was conducted to determine the effect of K management on the productivity and seed quality of soybean under normal and waterlogged conditions. The treatments comprised three factors, namely soybean genotypes (BU Soybean-1 and BU Soybean-2), waterlogging (WL) (control and WL for 4 days at the flowering stage (FS)), and K application (full dose as basal and 50% as basal +50% as top dress after termination of the flooding). The trial was laid out in a randomized complete block design with three replications. Findings revealed that BU Soybean-1 produced a higher number of pods and seeds pod-1 under control conditions with basal application of K. On the other hand, BU Soybean-2 produced taller plants and heavier grain, improving grain and straw yield under WL conditions when K was top dressed. The varieties absorbed a higher amount of nitrogen, phosphorus, and potassium under control conditions compared to WL when K was top dressed. Similarly, the seed protein content of both varieties was higher in the control condition with a top dressing of K. However, a higher percentage of seed germination was obtained from BU Soybean-2 in the control condition with a top dressing of K. Further, more electrical conductivity and more mean germination time were recorded in the case of BU Soybean-2 under WL with the basal application of K. Split application of 50% of recommended K fertilizer after the recession of flood water could be suggested for improved grain yield in flood-affected soybean growing areas.

Postharvest Quality of Sour Passion Fruit Under Irrigation Strategies with Brackish Water and Potassium Application in Two Crop Cycles

Postharvest Quality of Sour Passion Fruit Under Irrigation Strategies with Brackish Water and Potassium Application in Two Crop Cycles

Effects of potassium and phosphorous on growth and yield of soybean variety VNUAĐ2 in Gia Lam – Ha Noi

The experiment was carried out to determine effects of potassium and phosphorus fertilizers on growth and yield of the soybean variety VNUAĐ2. The experiment was conducted in the spring season of 2021 and was a split-plot design with 3 replications. Potassium levels included 0, 60, 80 and 100 kg/ha and phosphorous levels were 0, 70, 90 and 110 kg/ha. The effects of different fertilizer rates were determined through growth and development characteristics (plant height, number of leaves, number of nodes, number of branches), leaf area index, number and weight of nodules, yield components and yield. Results showed that phosphorus and potassium fertilizer application resulted in better plant growth and development than no fertilizer application. Also, the average plant height (47.4 to 50.5 cm), number of branches (2.2 to 2.6), number of nodules in the flowering period (51.2 to 56.3) and yields (1.77 to 1.81 tons/ha) with phosphorus application were better than the plant height (46.1 cm), number of branches (2.0), number of nodules (48.1) and yield (1.74 tons/ha) without phosphorus application. Different levels of fertilization affected the growth and development of VNUAĐ2 variety and its yield. The level of application of potassium (80 kg/ha) and phosphorus (90 kg/ha) significantly increased yield components and yield by 10,1 - 50% as compared with no fertilizer application. When compared with other fertilization levels, the application of potassium (80 kg/ha) and phosphorus (90 kg/ha) resulted in better total pod number of 38.1 pods/plant (30.9 - 36.5% higher), number of filled pods of 36.7 pods/plant (6.70 - 31.5% higher), percentage of 3-seeded pods of 12.9% (6.6 - 29.0% higher), individual yield of 11.42 g/plant (0.53 - 14.1% higher) and yield of 1.86 tons/ha (1.1 - 8.8% higher). Thus, the most suitable fertilizer rate for the soybean variety VNUAĐ2 in the spring season was 80 kg/ha of potassium and 90 kg/ha of phosphorus.

English

This study focused on the improving effect of external application of calcium and potassium on growth, ions and organic solutes accumulation in tossa jute plants grown under salt stress. Young plants were subjected in pots to ten treatments including the control without NaCl, 120 mM NaCl and a combination of 120 mM NaCl and an addition of 40 or 60 mM CaSO4, CaCl2, K2SO4 or KNO3. Plant growth, sodium, potassium, proline and soluble sugars contents were determined after two weeks. Results revealed that only the external application of CaSO4 and K2SO4 at 40 mM significantly improved the growth reduction induced by NaCl followed by CaCl2; whereas at 60 mM, only CaSO4 induced similar changes in plant growth. Only, the exogenous application of calcium at 40 mM induced a significant decrease (p<0.05) in the Na+ content and a significant increase (p<0.001) of the K+/Na+ ratio of leaves in comparison with salt stressed plants, while the two forms of calcium and K2SO4 induced a significant increase (p=0.05) in the K+ content. CaSO4 had the best improving effects on plants growth under salt stress, followed by K2SO4 and CaCl2 at 40 mM. This improving effect is due to a better exclusion of Na+ from the leaves, the maintenance of a high ionic selectivity ratio K/Na and/or a better accumulation of K+.   Key words: Corchorus olitorius, sodium, potassium, calcium sulphate, calcium chloride, potassium sulphate, potassium nitrate, proline, soluble sugars.&nbsp

Fruit growth, carbon allocation, and related enzymes in tomato under different irrigation and potassium application regimes

AbstractBackgroundThe increasing concentration of atmospheric CO2 not only affects the growing environment of crops but also aggravates the global greenhouse effect and further aggravates the problem of water shortage. The combined effect of water deficit and potassium (K) application has not been widely studied.AimsA pot experiment was conducted to investigate the effect of deficit irrigation (DI) and K application at different growth stages on carbon allocation and enzyme activities related to sugar metabolism.MethodsTomatoes were transplanted and planted on April 26, 2017 and harvested on August 15, 2017. Four irrigation regimes were implemented with two water levels (full irrigation‐W and DI‐W/2) in different growth stages, and each water treatment was equally divided into two subgroups: with K (K1) and without K (K0). Fruits from the first to fourth trusses of the tomato plants were sampled. Tomato growth, carbon allocation, and related enzyme activities were measured.ResultsThe fresh weight (FW), dry weight, and relative growth rate of dry mass were sensitive to irrigation amount under K fertilization, enhancing the promotion effect of irrigation on fruit. Meanwhile, carbon allocation was sensitive to irrigation amount under K regime. Sucrose synthase (SuSy), acid invertase (AI), and sucrose phosphate synthase (SPS) were also highly sensitive to irrigation amount under K application condition. Starch phosphorylase displayed a quadratic parabola for irrigation amount, and adenosine diphosphate glucose pyrophosphorylase (AGPase) was highly sensitive to irrigation amount without K fertilization. Carbon in the form of other carbohydrates, carbon in the form of soluble sugar (Csol), and fruit water content were the factors that had the greatest influence on the principal components. Classification by K‐means algorithm and canonical correlation analysis showed that FW, fructose, sucrose, and starch could be used as significant indicators of the dry matter components of the fruit for the treatment without K. In the case of K regime, SuSy, AGPase, AI, and Csol could be used as a significant indicator of the correlation analysis of carbon metabolism activity.ConclusionsThe factors related to the improvement of fruit quality and carbon allocation by deficient irrigation and K application were explored. Water stress changed the distribution of photosynthetic carbon between starch and soluble sugar. K application further changed the balance between soluble sugars and other compounds. In particular, it significantly increased the carbon content of soluble sugars and decreased that of other compounds. AI and SuSy are key enzymes affecting carbon metabolism under water‐deficient conditions.

Response of wheat to potassium and its fractions in Punjab soils

A pot experiment was conducted at screen house of Department of Soil Science, PAU, Ludhiana during rabi 2017-18 to evaluate the response of wheat to applied potassium. Twelve soil samples were taken from all over Punjab varying in available K. Potassium was applied @ 0, 15, 20, 25 and 30 kg K/ha soil. The mean grain yield varied from 12.39 to 20.13 g/pot in K sufficient soils (>137 kg K/ha) and 8.43 to 12.09 g/pot in K deficient soils (<137 kg K/ ha). Increase in grain yield was significant up to 25 kg K/ha in K sufficient soils, however in K deficient soils, wheat responded up to 30 kg K/ha. Application of 30 kg K/ha resulted in significant increase in content of K fractions (water soluble K (WSK), exchangeable K (EXK) and non exchangeable K (NEK) as compared to control in both K sufficient and deficient soils. WSK showed significant and positive correlation with EXK (0.964*) and NEK (0.872*) indicating dynamic equilibrium between these forms of K. About 70.5 and 93.4% variation in grain yield of wheat was due to the combined influence of WSK and EXK in K sufficient and deficient soils, respectively. NEK accounted for only 0.9 and 5.2% variation in grain yield in K sufficient and deficient soils, respectively. Hence, contribution of NEK towards wheat yield in K deficient soils was higher as compared to K sufficient soils. Therefore, K deficient soils are more responsive to potassium application as compared to K sufficient soils.

Effects of Potassium Application on Lilium davidii var. unicolor Growth, Polysaccharide Accumulation, and Metabolism

Lilium davidii var. unicolor is an important variety of lily with high economic, ornamental, edible, and medicinal values. Up to now, the research on polysaccharide as the main active substance is not vast, especially the effect of potassium on lily polysaccharide. Here, we investigated the effects of potassium fertilizer application on the growth and development, polysaccharide accumulation in the bulb, and differential metabolites in L. davidii var. unicolor. It was treated with fixed amounts of nitrogen (N) and phosphorus (P), and four K concentrations comprising K0 (0 mg·L−1), K1 (447.6 mg·L−1), K2 (671.4 mg·L−1), or K3 (895.2 mg·L−1). The growth indexes were determined for L. davidii var. unicolor under different K concentrations in different growth stages. The polysaccharide contents of the bulbs were determined using the sulfuric acid−phenol method. An analysis of the differential polysaccharide metabolites was also conducted. The application of potassium promoted the growth and increased the bulb polysaccharide content of L. davidii var. unicolor, and the most suitable K concentration of 671.4 mg·L−1 had the most significant effects. Non-targeted metabolomics analysis screened 37 differential polysaccharide metabolites under K0 and K2, where 25 were significantly upregulated and 12 were significantly downregulated. Three metabolic pathways were enriched in polysaccharide-related differential metabolites, i.e., the galactose metabolism, amino sugar and nucleotide sugar metabolism, and starch and sucrose metabolism. The results could provide a theoretical basis for an improved fertilization management and the high-quality cultivation of L. davidii var. unicolor.

Evaluation of the Effects of Nitrogen, Phosphorus, and Potassium Applications on the Growth, Yield, and Quality of Lettuce (Lactuca sativa L.)

Lettuce (Lactuca sativa L.), a popular edible vegetable, is highly responsive to mineral fertilizers. A two-year field trial was carried out to determine how nitrogen (N), phosphorous (P), and potassium (K) application ratios affected lettuce growth, yield, and quality. Within a certain range of nutrient application rate, the plant height, stem diameter, yield, and the concentrations of vitamin C and soluble sugar were higher than those without fertilization. Compared with no fertilization condition, the yield increased approximately 13.56–22.03%, 15.15–42.42% and 7.14–10.32% under increased N, P, and K application conditions, respectively. Furthermore, substantial quadratic parabola relationships were observed between lettuce yield and fertilizer application amounts as well as most quality traits. The nitrate concentration was proportional to the N fertilization rate, while the concentrations of soluble sugar and vitamin C positively correlated with N and P application ratios, respectively. The lettuce leaves had the largest N (60.59%) and K (52.25%) accumulations, whereas the lettuce stem had the highest P (46.33%) accumulation. Above all, the optimal N, P, and K application amounts for lettuce were 315 kg N ha−1, 210 kg P2O5 ha−1, and 285 kg K2O ha−1, respectively.

Effects of Exogenous (K+) Potassium Application on Plant Hormones in the Roots of Tamarix ramosissima under NaCl Stress.

Abiotic stresses such as salt stress seriously affect the growth and yield of plants. Tamarix ramosissima Lcdcb (T. ramosissima) is a widely cultivated halophyte in saline-alkali areas of the world. As an essential element for plant growth and development, K+ plays an irreplaceable role in improving the tolerance of plants to salt stress. However, there are few reports on the mechanism of K+ in promoting plant hormones to reduce the damage of NaCl stress to T. ramosissima. In this study, we sequenced the transcriptome of the roots of T. ramosissima which were treated with exogenous potassium (K+) for 0 h, 48 h and 168 h under NaCl stress, according to the changes in the expression levels of differentially expressed genes (DEGs) in T. ramosissima roots. Key candidate genes and metabolic pathways related to plant hormones were mined for analysis and further verified by quantitative real-time PCR (qRT-PCR). The results showed that under NaCl stress for 48 h and 168 h, there were a large number of DEGs in the roots of T. ramosissima, and the expression levels changed over time. In particular, we found that 56 plant hormone-related genes were annotated to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and with the increase of time, their expression levels were mainly up-regulated and involved in the related metabolic pathways to resist NaCl stress. It is worth noting that 7 DEGs related to abscisic acid (ABA), 28 DEGs related to auxin, 1 DEG related to ethylene (ET), and 1 DEG related to cytokinin (CK) were added within 168 h of exogenous potassium, and they were involved in alleviating the root damage of T. ramosissima under NaCl stress and played an important role. In addition, we found the plant hormone signal transduction pathway, which plays an important role in resistance to NaCl stress. As a result of this study, the molecular mechanism of plant hormones involved in applying exogenous potassium under NaCl stress is further understood, resulting in a better understanding of how exogenous potassium can alleviate the damage caused by NaCl under stress in T. ramosissima.

Strengthening leaf physiological functioning and grain yield formation in heat-stressed wheat through potassium application.

Wheat crops are highly sensitive to high temperatures during their reproductive and grain-filling phases. We hypothesized that potassium could increase thermotolerance in wheat during grain filling by protecting cellular organelles, particularly chlorophyll, from heat injury. Two wheat genotypes, Ujala-16 (relatively heat tolerant) and Anaj-17 (relatively susceptible) were grown in pots and were submitted to 4 and 8 days of heat stress under polythene sheets 1 week after anthesis. One day before the onset of heat stress, 2% potassium (K) as K2SO4 was sprayed on all the plants. Flag leaves from both genotypes were collected after 4 and 8 days of heat stress. Leaf physiology changes were measured to quantify heat damage and to understand the K-induced recovery mechanism. The crop was harvested 125 days after sowing, and grain yield data were collected. Increasing duration of heat stress significantly impaired leaf physiology and grain yield of both studied wheat genotypes. Compared with control (under optimum temperature), 4 and 8 days heat-stressed plants produced 11 and 19% lesser grain yield per spike (averaged across genotypes and in the second years of study), respectively. Likewise, 4- and 8-days heat-stressed plants had 15 and 37% (averaged across genotypes and in the second years of study) lower flag leaf photosynthesis, respectively, compared with control plants. Across the genotypes, 8-days heat caused significantly more grain yield loss in Anaj-17 during the second year than in Ujala-16. Foliar K significantly restored leaf chlorophyll, Pn, Fv/Fm by reducing cellular membrane damage in the heat-stressed plants. This physiological recovery and activation of the plant defensive system by K under high-temperature stress protected the growth and grain development. For example, K–treated plants produced 19% higher 1,000 grain weight in 8 days of heat stress (across genotypes and in the second years of study) compared with water-treated plants under the hot environment of the respective thermal regime. Our study suggests that wheat performance under terminal heat stress can be improved through the exogenous application of K.

Farmland scale and chemical fertilizer use in rural China: New evidence from the perspective of nutrient elements

Chemical fertilizer overuse has resulted in serious agricultural pollution. Many studies have analyzed the effect of farmland scale on fertilizer use. Fertilizer has different nutrient elements, such as nitrogen, phosphorus and potassium, but little evidence of the effect of farmland scale on nutrient elements application rate has been found. Using micro-survey data of 1015 households across 5 provinces of China, this study empirically identified the effect of farmland scale on fertilizer use from the perspective of nutrient elements. The instrumental variable method was used to solve endogenous problems. Results showed that farmland scale had a significant negative impact on the total nitrogen application rate from fertilizer and the nitrogen application rate from urea but had no statistically significant impact on the nitrogen application rate from non-urea, phosphorus application rate or potassium application rate. The nitrogen application rate on average decreased by 0.93% for each 1% increase in average farm scale. Heterogeneity analysis indicated that the effect of farmland scale on the nitrogen application rate were different among groups with different crops, gender, age and education of head of household, and differences in proportion of farmland transfer. Scale effect was found only in maize cultivation. The proportion of farmland transfer is higher, the scale effect for fertilizer reduction is less obvious. The findings offer new insights that farmland scale has heterogeneity effects on nutrient element application rates and fertilizer reduction should focus on nitrogen application rate from non-urea.

Effects of the potassium application rate on lipid synthesis and eating quality of two rice cultivars

Lipid content has an important effect on rice eating quality, but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood. Potassium (K) has a strong influence on rice quality and the requirement for K fertilizer in rice is greater than for nitrogen (N) and phosphorus (P) fertilizers. To investigate the effects of K fertilizer on the lipid synthesis and eating quality of rice, we used Nanjing 9108 (NJ9108, japonica) and IR72 (indica) rice as experimental materials and four K levels: K0 (0 kg ha–1), K1 (90 kg ha–1), K2 (135 kg ha–1) and K3 (180 kg ha–1). The results showed that the lipid content, free fatty acid (FFA) content, unsaturated fatty acid (UFA) content, malonyl-CoA (MCA) content, phosphatidic acid (PA) content, lipid synthesis-related enzyme activities and eating quality first increased and then decreased with increasing K in both cultivars. The maximum values were obtained under K2. However, the saturated fatty acid (SFA) content showed the opposite trend. No significant differences were found in pyruvate (PYR) content among the K treatments. The protein and oxaloacetic acid (OAA) contents and phosphoenolpyruvate carboxylase (PEPCase) activity of NJ9108 first decreased and then increased with increasing K, and the minimum values were obtained under K2; while IR72 showed the opposite trend and the maximum values were obtained under K1. Overall, increasing K optimized the fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis. The optimal K application rate for lipid synthesis, eating quality and grain yield was 135 kg ha–1 for both cultivars.

​Effect of Foliar Applied Nitrogen with Growth Regulators (2,4 D, GA3, Amrut-pani) and Soil Applied Potassium on the Management of the Rough-skin Disorder of Nagpur Mandarin (Citrus reticulata Blanco)

Background: Rough-skin disorder mainly occurs in 6-12 years old young and senile orchards of Nagpur mandarin due to excess application or availability of potassium. The characteristics of rough-skinned fruits are large fruit size with rough textured peel, segments are loose intact with rind, improper fruit shape (fruit length to breadth ratio is equal to one or more than one), reduced juice per cent and TSS. Methods: Based on the incidence of rough-skin disorder, an orchard of Nagpur mandarin was earmarked at Hetikundi village of Wardha district, Maharashtra for Mrig bahar during 2020. The selected orchards are 10 years old, spaced at 6 m x 6 m and grafted on Rangpur lime rootstock. At harvest, yield and yield attributes, fruit physical characteristics and critical quality characteristics viz. TSS, acidity, TSS/ acidity ratio and vitamin C content of disordered and normal fruits were recorded according to treatments. Result: Foliar application of plant growth regulators like 2,4-D 15 ppm and GA3 15 ppm and reducing soil application of potassium in high potassium available soils reduced the rough skin and improved the rind texture and physicochemical characteristics at harvesting in mrig bahar.

Indigenous Nutrient Supplying Capacity of Young Alluvial Calcareous Soils Favours the Sustainable Productivity of Hybrid Rice and Maize Crops

The crop productivity in calcareous soils is low due to their low organic matter content, high pH levels and improper nutrient management without considering the indigenous nutrient supplying capacity and crop yield potential; therefore, this study was conducted for a quantitative assessment of the nutrient supplying capacity of a calcareous soil on the productivity of hybrid and conventional rice and maize crops using an omission plot technique. The treatments included the ample application of Nitrogen (N), Phosphorus (P), Potassium (K), Sulphur (S) and Zinc (Zn), and an unfertilized check and omissions of N, P, K, S and Zn in rice and maize for six cropping seasons. The impact of the nutrient omission towards crop productivity was highest for nitrogen followed by phosphorous, potassium, zinc and sulphur. The total grain yield (3 yr average) in the hybrid rice–maize system was highest (16.32 t ha−1) for the optimum fertilized plot and lowest (6.34 t ha−1) for the unfertilized check. The sustainable yield index indicated that hybrid and conventional rice-maize cropping systems were more sustainable in the amply fertilized plot than in the nutrient-limited and unfertilized treatment plots. The average percent contributions of nitrogen, phosphorous, and potassium from the soil towards total nutrient removal were 36, 80 and 137 kg ha−1, in the hybrid system and 24, 54 and 104 kg ha−1 in the conventional system, respectively. The return on investment (ROI) of the N, P, K, S and Zn for the hybrid rice was 21.2, 7.1, 6.7, 4.1, and 0.3 USD, respectively, while for the maize it was 28.8, 7.6, 4.9, 6.5, and 0.7 USD, respectively. The results suggest that there is a direct link between the soil nutrient supplying capacity and the nutrient requirements by different types of crops in calcareous soil; therefore, the omission plot technique used for the assessment of the indigenous nutrient supplying capacity could be used in the larger domain for improved nutrient management, through synchronization with a targeted crop yield for improved productivity, soil fertility, nutrient use efficiency and farm income.

Effect of Potassium Application Rate on Dry Matter Yield and Forage Nutritive Value in Alfalfa

The United States is the largest producer of alfalfa (Medicago sativa L.) however there is still a wide variation in yield among states. Potassium (K) is one of the key plant macronutrients that affect alfalfa yield and stand persistence. To the best of our knowledge, the evaluation of K rates on alfalfa forage yield and quality attributes has not been done in the United States. Thus, the main objective of this study was to evaluate the effect of K rates along with harvesting intervals (HI) and varieties on alfalfa dry matter yield (DMY), forage nutritive value, and soil K content. The experiment was carried out in a split-split plot with two HI (28 and 35-day after the first cut), two varieties (Hi–Gest 360: reduced-lignin and AFX 457: conventional), and four K application rates (0, 56, 112, and 168 kg K2O ha-1) in a randomized complete block with four replications. The results indicated that harvesting alfalfa at a shorter interval (28-day) resulted in higher dry matter yield and forage nutritive value than a longer harvest interval (35-day). Yield, nutritive values, and soil K content were, however, not significantly influenced by alfalfa variety and K rates. Further research is essential to quantify the actual trade-off between applied K and soil and plant K content in alfalfa production.

Polythene mulch and potassium application enhances peanut productivity and biochemical traits under sustained salinity stress condition

As peanuts are sensitive to salinity, physiological and agronomic responses to mulching and varied potassium rates were explored to boost peanut yield. During 2013–14 and 2014–15, a field study with 12 treatment combinations using three levels of saline irrigation water (control, 2.0 and 4.0 dS m−1) and mulching (Plastic mulch and control) as main plot, and three levels of potassium treatment (control, 30 and 60 kg K2O ha−1) assisted in sub plots. Results revealed that, application of irrigation water at 2.0 and 4.0 dS m−1 salinity exhibited 46.7–133.3% lower nodule count and pod yield reduced by ∼22.5% at successive increase in salinity over best availability water with 0 dS m−1. Salinity levels lowered free amino acids and oil content, but protein and sugar quantities rose modestly. Polythene mulch enhanced peanut pod production, haulm yield, and oil content by 23.9%, 24.6%, and 49.5%, respectively. Potash fertilizer applied at 60 kg ha−1 has a greater impact on pod yield (2.50 Mg ha−1) than lower potassium fertilizer levels. External potassium application didn't affect peanut biochemistry. Adopting polythene mulch with 2.0 dS m−1 salinity level irrigation water increased pod yield by 6.37–116.1%. Polythene mulch + 60 kg K2O ha−1 + 2.0 dS m−1 increased 100 pod weight (88.4 g), root length (8.67 cm), nodules (9.00), and oil content (50.2%) over other combinations. Five principal component analysis (PCA) main components explained 84.4% variation with PC1 explaining 52% and correlating positively with yield related traits, nodule numbers and oil content. Polythene mulch containing 30–60 kg K2O ha−1 increased peanut yield, biochemical parameters, and oil content under similar growing conditions. Therefore, use of polythene mulch with combination of optimum potassium fertilizer application can be effectively used with salinity irrigation water up to 2.0 dS m−1 without compromising in yield and quality loss of peanut.

Effect of potassium application on crop productivity in Boro rice production

Effect of potassium application on crop productivity in Boro rice production

Onion downy mildew severity in no-tillage irrigation under nutrient budgeting and population densities

We analyzed the relationship between nutrient (N and K) parceling and population density on the severity of onion downy mildew under no-tillage fertigation cultivation in the conditions of Alto Vale do Itajaí (Barzil). For this purpose, field trials were conducted in the years 2017, 2018 and 2019, in Ituporanga (Barzil). The treatments corresponded to four population densities (300, 400, 500 and 600 mil plants ha-1) subjected to applications of nitrogen (150 kg N ha-1) and potassium (127.5 kg K2O ha-1) distributed throughout the vegetative cycle of the crop via fertigation on a weekly, biweekly and monthly basis, based on the absorption curve of these nutrients for the cultivar Empasc 352-Bola Precoce. In fertigated no-tillage systems, nutrient (N and K) tranches do not influence the severity of downy mildew. The severity of downy mildew increases linearly with increasing population density, especially from 500 mil plants per ha-1.

Single and poly capsule sesame (Sesamum indicum L.) productivity in response to plant growth-promoting rhizobacteria and foliar application of silicon, potassium, and calcium

Single and poly capsule sesame (Sesamum indicum L.) productivity in response to plant growth-promoting rhizobacteria and foliar application of silicon, potassium, and calcium