K2O Application Research Articles

Soil Heating Significantly Increases Leaf Magnesium Concentration and Fruit Yield in Tomatoes Produced in a Plastic Greenhouse During Winter

Magnesium (Mg) deficiency frequently occurs in tomato leaves grown in plastic greenhouses during winter in northern China. In this study, field experiments were conducted to test the effects of soil temperature and the potassium (K) fertilizer application rate on tomato K and Mg absorption and fruit yield. The treatments were soil non-heating (control) and soil heating with electric hotlines, with three K2O application rates (180 kg ha−1, 580 kg ha−1, and 980 kg ha−1). The soil heating treatments increased the average soil temperature by 2.1 °C during the day, significantly increasing leaf Mg and chlorophyll concentrations by 21.3% (from 6.86 to 8.32 g·kg−1) and 12% (from 1.25 to 1.40 mg·g−1), respectively, and fruit yield by 5.5% (from 150 to 158.2 t·ha−1) and significantly decreasing the leaf K concentration by 10.5% (from 29.4 to 26.3 g·kg−1). However, the K fertilizer application rate had no significant effect on fruit yield and leaf K and chlorophyll concentrations. Moreover, the soil non-heating treatments showed a significant negative correlation between leaf K and Mg concentrations. Low soil temperature exacerbates K–Mg ion antagonism, which is the main driving factor for Mg deficiency in winter greenhouse tomatoes. Soil heating can significantly promote Mg absorption and improve fruit yield in tomatoes produced in plastic greenhouses during winter. The results of this study provide theoretical and technical support for regulating Mg nutrition in tomatoes grown in plastic greenhouses in northern China.

Optimized nutrients management improved citrus yield and fruit quality in China: A meta-analysis

Clarifying current situation of farmers' fertilization and yield in citrus producing areas and the effects of different fertilization measures can provide a scientific basis for improving the yield and quality of citrus in China. We retrieved 92 literatures on citrus fertilization from the CNKI and Web of Science to examine the impacts of nitrogen (N), phosphorus (P or P2O5), and potassium (K or K2O) fertilizer dosage and partial productivity under farmers' conventional fertilization and experts' optimized fertilization, as well as the effects of optimized fertilization measures on citrus yield and quality by using meta-analysis approach. The average conventional application rates of N, P2O5, and K2O were 507.3, 262.2, and 369.3 kg·hm-2 in citrus production in China. Compared with conventional fertilization, optimized fertilization resulted in a reduction of N and P2O5 by 14.7% and 8.3%, an increase in K2O application by 6.6%, which promoted partial productivity of N, P2O5, and K2O fertilizers by 7.8%, 18.4%, and 14.7%, correspondingly. The optimized fertilization resulted in 11.9% and 2.8% increase in fruit yield and single fruit weight, while improved vitamin C content (Vc, 3.1%), total soluble solids (TSS, 5.9%) and total sugar content (TSC, 8.6%). Additionally, it also led to a reduction in titratable acid (TA, -3.4%) and total acid content (TAC, -3.6%), and consequently elevated the TSS/TA (14.0%) and TSC/TAC (9.5%). Among different optimized fertilization methods, the effect of optimized NPK + medium and/or micro element fertilizer on citrus yield and fruit quality was the best, especially NPK decrement ≤25% between optimized NPK measures. The effect of conventional NPK + organic fertilizer was higher than conventional NPK + medium and/or micro element fertilizer. However, different citrus varieties, including mandarins, pomelos, and oranges, showed different responses to optimized fertilization. Optimized fertilization management could synergistically improve citrus yield, fertilizer use efficiency, and fruit quality. Therefore, the strategy of integrated nutrient management1 with reducing NPK fertilizer, balancing medium and/or micro nutrient fertilizer and improving soil fertility by organic fertilizer should be adopted according to local conditions in citrus producing areas of China.

Cold Hardiness in ‘Alphonse Lavallee’ (Vitis vinifera L. cv) Grape Dormant Buds and Phloem Tissue: Seasonal Insights and Some Treatment Impacts

Grapes are highly susceptible to cold damage during critical developmental stages, impacting viticulture. Understanding the intricate dynamics of cold hardiness in grape dormant buds and phloem tissue is crucial for developing effective mitigation strategies. In this study, we investigated the LT50 values, representing the temperature at which 50% of buds are damaged, under different treatments and sampling times. In our research, we evaluated the effects of four treatments—potassium oxide (K2O), calcium chloride (CaCl2), seaweed (SW), and a control—on the cold hardiness of grapevine buds and phloem tissue. Primary bud LT50 values varied across seasons, with January at −22.46 °C, February at −22.35 °C, and March at −20.45 °C. K2O treatment showed a trend toward improvement, although the difference from the control (−21.99 °C) was not statistically significant. Regarding LT50 values, CaCl2 and SW applications did not significantly differ from the control. Tertiary buds, however, exhibited a substantial enhancement in cold hardiness with K2O application, displaying significantly lower LT50 values compared to the control (−23.55 °C). Phloem tissue LT50 values did not significantly differ among treatments, showing less variability. Bud water content significantly increased with K2O application in all sampling periods (January: 35.41% vs. 35.61%; February: 34.03% vs. 39.16%; March: 42.40% vs. 37.82%), while shoot water content remained stable. In conclusion, K2O emerges as a key influencer, particularly in enhancing the cold hardiness of tertiary buds. These insights contribute to the knowledge base for targeted frost mitigation strategies in viticulture.

Infrared thermometry-based stress indices as indicators of yield performance and seasonal evapotranspiration in potato plants grown under different moisture and potassium regimes

As the demand for food continues to rise and water availability challenges intensify, the delicate equilibrium between efficient water usage and sustainable agricultural production has become increasingly pivotal. Recognizing the significance of water stress monitoring and nutrient management in the country's agricultural landscape, two years of field trials (2018–2019 and 2019–2020) were conducted at the Regional Research Station, Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia, to demonstrate the efficiency of canopy temperature-based indices for monitoring crop water stress in potato (cv. Kufri Jyoti) under varied irrigation (IW:CPE = 0.4, 0.8, 1.2 and 1.6) and potassium doses (K2O @ 100, 150 and 200 kg ha−1). The seasonal evapotranspiration of potato plants ranged from 121.0 mm to 320.9 mm during the crop growth period, and it exhibited a quadratic relationship with both the total dry biomass and the tuber yield. In 2019–2020, the highest water use efficiency (WUE) of 12.74 kg m−3 was obtained from the application of IW; CPE= 1.20 with the application of K2O @ 200 kg ha−1. In the following year, the highest WUE of 9.78 kg m−3 was obtained from irrigation at IW:CPE= 1.60, along with K2O application @ 200 kg ha−1. During a major part of the growth period, the canopy air temperature difference (CATD) was greater in the treatments in which irrigation was applied at IW:CPE = 0.4 and 0.8 than in those in which irrigation was applied at higher levels, i.e., IW:CPE = 1.2 and 1.6, implying the effectiveness of CATD as a stress indicator. The stress indices, stress degree days (SDD) and crop water stress index (CWSI) accumulated over the crop growing season showed decreasing trends with increasing irrigation and potassium doses. Both the accumulated SDD and accumulated CWSI showed a strong inverse relationship with tuber yield. The significant linear relationship between tuber yield and the seasonal accumulation of both infrared thermometry-based stress indices (i.e., SDD and CWSI) may help to predict crop yield in response to seasonal moisture stress and thus aid in strategic crop planning under the limited availability of irrigation.

Sesame (Sesamum indicum L.) growth properties and yield attributes are associated with potassium level in response to drought stress

Little attention is paid to the mitigating effect of different potassium (K) levels on sesame (Sesamum indicum L.) growth performance in response to drought stress (DS). A pot experiment was performed under DS conditions along with four K levels (0, 60, 120 and 180 kg ha−1, denoted as DK0, DK1, DK2 and DK3 respectively), and 120 kg ha−1 of K2O application under normal watering was set as control (CK). Results showed that the plant height, specific leaf weight, leaf water content, chlorophyll content, crop growth rate and biomass were significantly decreased by 6.9%, 15.3%, 7.3%, 17.9%, 55.6% and 34.1%, respectively, as compared to CK whereas K could alleviate the adverse effects of drought on the aforementioned parameters, and the mitigation was more prominent as K rates increased. The decrease in capsule number per plant (1.72 g) primarily accounted for yield loss (1.95 g) induced by DS. Expectedly, K supply compensated for the yield reduction to an extent and the maximum compensation was recorded under DK3, which increased by 50.0% as compared to DK0. Additionally, enhanced yield and yield components were positively correlated with K accumulation as it was further evidenced by significantly increased K uptake in plant tissues. For every extra 1 g of K absorbed by the plant, the yield per plant would increase by 16 g However, the K utilization efficiency showed a downward trend along with increased exogenous K supply under DS. In conclusion, K application at the rate of 120 kg ha−1 is an economical and effective approach for alleviating drought susceptibility in sesame crops.

Effect of GA3 and Potassium on Growth and Yield in Red Radish (Raphanus sativus L.) under Subtropical Conditions of Jammu

An experiment was carried out at Vegetable Experimental Farm, Division of Vegetable Science, SKUAST Jammu during Rabi season of 2022-2023. The experiment was laid out under factorial RBD design with three replications comprising of sixteen treatments. The treatments consisted of four doses of Potassium i.e., 40, 50, 60 and 70 kg/ha and four concentrations viz. 0,100,200 and 300 ppm of GA3. The growth and yield parameters maximum viz. shoot length (34.15 cm), root length (18.73 cm), number of leaves/root (14.30), root weight (220.49 g), shoot weight (119.47 g), root- shoot ratio (2.04), fresh root shoot yield (112.42 q/ha) were recorded with 200 ppm GA3 application. Similarly, highest shoot length (29.06 cm), root length (17.53 cm), number of leaves/root (11.18), root weight (171.67 g), shoot weight (104.84 g), root-shoot ratio (1.87), fresh root shoot yield (92.31 q/ha), were recorded with 50kg/ha K2O application. However; highest root length (19.20 cm), number of leaves/root (14.87), root weight (226.14 g), shoot weight (123.54 g), root-shoot ratio (2.10), fresh root shoot yield (115.90 q/ha) were recorded with treatment combination G3K2 (200 ppm GA3 + 50 K2O/ha). Based on the investigation, it can be concluded that the application of 200 ppm GA3 at 30 days after sowing with 50 kg potassium/ha resulted in the highest growth parameters and yield.

The Nutrient Expert decision support system improves nutrient use efficiency and environmental performance of radish in North China

Excessive fertilization has led to nutrient use inefficiency and serious environmental consequences for radish cultivation in North China. The Nutrient Expert (NE) system is a science-based, site-specific fertilization decision support system, but the updated NE system for radish has rarely been evaluated. This study aims to validate the feasibility of NE for radish fertilization management from agronomic, economic, and environmental perspectives. A total of 46 field experiments were conducted over four seasons from April 2018 to November 2019 across the major radish growing regions in North China. The results indicated that NE significantly reduced N, P2O5, and K2O application rates by 98, 110, and 47 kg ha−1 relative to those in the farmers’ practice (FP), respectively, and reduced N and P2O5 inputs by 48 and 44 kg ha−1, respectively, while maintaining the same K2O rate as soil testing (ST). Relative to FP and ST, NE significantly increased radish yield by 2.7 and 2.6 t ha−1 (4.2 and 4.0%) and net returns by 837 and 432 USD ha−1, respectively. On average, NE significantly improved the agronomic efficiency (AE) of N, P, and K (relative to FP and ST) by 42.4 and 31.0, 67.4 kg kg−1 and 50.9, and 20.3 and 12.3 kg kg−1; enhanced the recovery efficiency (RE) of N, P, and K by 11.4 and 7.0, 14.1 and 7.5, and 11.3 and 6.3 percentage points; and increased the partial factor productivity (PFP) of N, P, and K by 162.9 and 96.8, 488.0 and 327.3, and 86.9 and 22.4 kg kg−1, respectively. Furthermore, NE substantially reduced N and P2O5 surpluses by 105.1 and 115.1 kg ha−1, respectively, and decreased apparent N loss by 110.8 kg ha−1 compared to FP. These results indicated that the NE system is an effective and feasible approach for improving NUE and promoting cleaner radish production in North China.

Azotlu ve potasyumlu gübrelemenin kivi bitkisinde verim ve meyve kalitesi üzerine etkisi

ABSTRACT In this research, increasing doses of nitrogen (8-16-24-32 kg N da-1) and potassium (0-8-16-24-32-40 kg K2O da-1) fertilizers were applied to Hayward kiwifruit (Actinidia deliciosa) to determine their effects on the yield and some fruit quality characteristics. The research was started in a kiwi orchard established in 2004 in Ordu, in the vegetation period of 2015-2016, and was carried out in a randomized block design with 4 replications for two years. In general, the yield decreased with increasing N rates while it increased irregularly with the increasing K rates, and the highest yield was achieved by applying 24 kg of N and 40 kg of K2O per decare in both years. Nitrogen fertilization provided a somewhat increase in fruit weight in the first year and tended to decrease in the second year. Total antioxidant capacity generally showed a fluctuating trend in the first year and an increasing trend in the second year considering the nitrogen application. With increasing potassium applications, the total antioxidant activity and vitamin C content of fruits increased up to a certain level and then decreased. Total soluble solids content (SSC) and titratable acidity (TA) generally tended to decrease with potassium applications. Although fruit firmness generally varied considerably with nitrogen and potassium applications, higher fruit firmness was observed at higher doses. Nitrogen application generally increased the total phenolic content. When the yield, fruit weight and fruit quality were evaluated together, it was determined that 16 kg N and 32 kg K2O application per decare was more appropriate.

Impact of Long-Term Manure and Mineral Fertilization on Accumulation of Non-Structural Carbohydrates in Lucerne Forage

Fertilization management affects both productivity and nutritive value of forage legumes. However, there are few studies about changes in lucerne non-structural carbohydrates under long-term fertilization. The aims of this study were to compare the effects of mineral fertilization and organic manure on lucerne plant parts (leaf, stem) starch and water-soluble carbohydrate (WSC) accumulation in association with canopy structure following 60 years of different fertilization management approaches. Treatments investigated were: two contrasting levels of mineral N, P2O5 and K2O application (0:0:0 and 91:71:175), each with and without farmyard manure. Changes were mainly reflected in WSC content where intensive mineral fertilization consistently reduced the stem and forage WSC in contrast to unfertilized control or manure alone. These changes could be associated with a dilution effect presented by the highest increase of maximal stem length at these treatments. Manure improved leaf and forage WSC despite the associated increase in maximal stem length and leaf weight ratio, probably as a result of improved soil environment together with the potentially increased presence of arbuscular mycorrhizal fungi. Results showed that manure fertilization has potential for improvement of lucerne WSC, despite some negative relationships between lucerne canopy traits and sugar content.

Effect of Integrated Potassium Application on Growth, Yield and Micronutrient Uptake by Forage Maize (Zea mays L.)

A pot experiment was conducted during kharif season of 2019 to carry out the study on “Interactive effect of potash (K2O), potassium mobilizing bacteria (KMB) and FYM on forage yield, nutrient uptake by forage maize and soil fertility in a loamy sand soil of middle Gujarat”. Application of K2O @ 60 kg ha-1, KMB and FYM recorded significantly the highest plant height of forage maize at harvest over respective control. Crop fertilized with K2O @ 60 kg ha-1 and KMB gave significantly the highest green forage and dry matter yield. The results indicated that application of K2O @ 60 kg ha-1, potassium mobilizing bacteria recorded significantly the highest uptake of N, P, K, Fe and Zn by crop at harvest. Significantly the highest uptake of N, K and Cu were found with application of FYM @10 t ha-1. Significantly the highest K uptake by maize as well as higher P and Zn uptake by maize were observed due to interaction effect of K × KMB (60 kg K2O ha-1 with KMB). In case of N and Cu uptake by maize were noted the Significantly higher due to interaction effect of K × KMB (30 kg K2O ha-1 with KMB) and K × KMB × FYM (60 kg K2O ha-1 with KMB and FYM), respectively. The integrated use of potassium fertilizers along with KBM or in combination with FYM significantly improved the maize grain and nutrient uptake.

Response of garlic (Allium sativum) to potassium application in loamy sand alluvial soil

A 2-year experiment was conducted during rabi 2015-17 at Bathinda to study the response of garlic (Allium sativum L.) to basal application of potassium chloride and foliar application of KNO3 (potassium nitrate) in a loamy sand alluvial soil. The basal application of K2O (50 kg/ha) caused non-significant increase in number of leaves/ plant, bulb weight, number of cloves/bulb, 50-clove weight and bulb yield, and significant but marginal increase in plant height (3.2%), bulb equatorial diameter (2.9%), benefit: cost ratio (12.0%) and A-grade bulb yield (13.7%) over control. The foliar application of KNO3 gave better results in improving growth, bulb and yield parameters by low (4-5%), moderate (8-24%) and high magnitude (43-52%), respectively. The quantum of increase was higher at 3% concentration of KNO3 than at 2% with equal number of sprays at same crop stage. The increase in cured bulb yield exhibited an upward trend with increasing number of sprays from two to five at both concentrations. Although, the highest increase over control in cured bulb yield (42.8%) and bulb weight (24.2%) was recorded by five sprays of KNO3 @ 3% which was at par with four sprays at same concentration, the former gave higher benefit: cost ratio as it produced significantly higher grade-A bulb yield than the latter. Therefore, five sprays of KNO3 @ 3% at 30, 45, 60, 75 and 90 days after sowing may be done to improve yield potential of garlic in loamy sand alluvial soil of South-Western Punjab.

Physiological and nutritional significance of potassium application under sole and intercropped maize (<em>Zea mays</em> L.)

Highlights - Potassium nutrient management in maize-soybean strip intercropping can increase the resource use efficiency. - Compared to the T0 (no potassium), T2 (80 kg ha–1 on maize) application increases the light interception and leaf area index of maize by 17% and 38% respectively. - Regression analysis reveals a positive relationship between physiological parameters measured at R2 and at R6 growth stages in maize under maize-soybean strip intercropping. - High K2O (80 kg ha–1) inputs enhanced the partitioning of biomass production in maize. - Overall, the optimum K2O application increased the maize yield by 16% under maize-soybean strip intercropping system relative to control.
 
 Globally, maize is an essential food and fodder crop. Fertilisers, as soil amendments, particularly K2O, could increase maize yields. A Two-year field research was designed in 2018- 2019 to examine the influence of three-potassium fertiliser applications on maize-soybean strip intercropping and sole-maize yield components. A Randomized complete block design with three replications was used, and one of three K2O doses (T0, 0; T1, 40:30; T2, 80:60 kg ha–1) was given in each plot. The effects K2O treatments on photosynthetic characteristics, photosynthetic active radiation, leaf area index, total biomass accumulation, and seed yield were investigated at V6, R2, R4, and R6. Compared to T0, maize-soybean strip intercropping system and sole-maize results showed T2 maize enhanced the light interception by 14, 26, 15, and 17% at V6, R2, R4, and R6 respectively. Maize increased the partitioning of biomass to cob and seed by 8 and 10% at R6, respectively in T2, relative to T0 treatment. T2 showed a higher green leaf area than T0; K2O applications led to an enhancement in leaf area index at R6 by 38%, under T2, and subsequently increased the photosynthetic rate at R4 and R6 by 8% and 6% respectively, in both years of the study. These results suggest that we may increase the accumulation of biomass and the yield of the maize seed under maize-soybean strip intercropping system and sole-maize by optimum K application in maize plants.

Potassium fertilization for white oat and maize in integrated crop‐livestock system under no‐tillage

AbstractIntegrated crop‐livestock systems (ICLS) are diversified agroecosystems characterized by the rotation, succession or mixtures of agricultural, livestock or forestry activities, in no‐tillage systems. In ICLS with trees, the tree modifies the light and water availability, and might generate root competition for nutrients, like potassium (K). The study aims to evaluate dry matter (DM) and macronutrients accumulation in white oat, DM and grain yield of maize, and the K use efficiency (KUE) by these crops cultivated in an ICLS with eucalyptus. The experimental design was a randomized block in a split‐plot design with three replications. Plots consisted of four cultivation positions (CP) between the tree rows, where CP1 (0 to 4 m distance) refers to a position close to the trees; CP2 (4 to 8 m distance) and CP4 (12 to 16 m distance) corresponds to two intermediate positions between rows; and CP3 (8 to 12 m distance) corresponds to a central position between rows. In subplots, four potassium oxide (K2O) annual doses were assigned, with potassium chloride being applied on the surface, where each rate was half the rate applied at sowing of each crop. DM and macronutrients accumulation in white oat shoot decreased due to eucalyptus shadow (64.5% light restriction). Responses of maize DM and grain yield to K2O addition were different among CPs, possibly owing to different light patterns. No changes in the maize yield were observed with K2O application in CP1 and CP2. However, for other positions, quadratic responses in grain yield were observed. In ICLS with eucalyptus in a subtropical region of Brazil, the reduction of K fertilization led to lower yields in white oat and maize. As KUE was high in plots with low K rate, the production cost in ICLS with trees may be decreased if massive production is not required.

MACRONUTRIENT RATES AND MULTIFUNCTIONAL MICROORGANISMS IN A TROPICAL FLOODED RICE CROP

ABSTRACT Tropical flooded rice production systems require a high input of fertilizers and chemical defensive. The use of plant growth-promoting rhizobacteria (PGPR), a sustainable component of this system, can increase nutrient-use efficiency and lead to significant increases in the grain yield of tropical flooded rice crop. This study aimed to determine the effect of the microorganism BRM 32110 (Bacillus thuringiensis) in combination with nitrogen (N), phosphorus (P) and potassium (K) application rates on the physiological and agronomic performance of tropical flooded rice plants. Trials were performed in the 2016/2017 growing season in Formoso do Araguaia, a city in Tocantins state, Brazil. Three independent experiments (E1, E2, and E3) were performed in a randomized block design in a 4 x 2 factorial scheme with three replications. E1 comprised four N application rates (0, 40, 80 and 120 kg N ha-1) with and without the addition of BRM 32110, E2 comprised four P2O5 application rates (0, 40, 80 and 120 kg P2O5 ha-1) with or without BRM 32110, and E3 comprised four K2O application rates (0, 20, 40 and 60 kg K2O ha-1) with and without BRM 32110. In fertile soil, there were no interactions between the rhizobacterium BRM 32110 and the N, P or K application rates. BRM 32110 improved nutrient uptake and, on average, increased shoot dry matter by 8%, photosynthesis rate by 14% and grain yield by 11% in the flooded rice plants. Our results suggest that the use of multifunctional microorganisms is a good strategy for improving flooded rice grain yield sustainably.

GROWTH AND POST-HARVEST FRUIT QUALITY OF WEST INDIAN CHERRY UNDER SALINE WATER IRRIGATION AND POTASSIUM FERTILIZATION

ABSTRACT The study was conducted to evaluate the growth and physicochemical quality of West Indian cherry cv. BRS 366-Jaburu, as a function of saline water irrigation and potassium fertilization. The research was conducted under greenhouse conditions in Campina Grande-PB. The experimental design was randomized blocks in a 2 x 4 factorial arrangement, which consisted of two levels of irrigation water electrical conductivity - ECw (0.8 and 3.8 dS m-1) and four levels of potassium of 50, 75, 100 and 125% of the recommendation, in which the dose of 100% was equivalent to 19.8 g of K2O per plant year-1, with three replicates and one plant per replicate. Water salinity of 3.8 dS m-1 inhibited the absolute and relative growth in diameter of the rootstock and scion of West Indian cherry plants, in the period from 100 to 465 days after transplanting. The interaction between saline levels and potassium doses was significant for hydrogen potential, soluble solids and anthocyanins levels in BRS 366-Jaburu West Indian cherry fruits, with the highest values obtained in plants fertilized with 125, 125 and 50% of the K2O recommendation and under water salinity of 3.8, 3.8 and 0.8 dS m-\ respectively. Increasing doses of K did not attenuate the effects of salt stress on the relative growth in rootstock stem diameter, fruit polar diameter and anthocyanin contents of West Indian cherry. Soluble solid contents in West Indian cherry pulp increased with application of K2O.

Nitrogen and potassium fertilization affects banana production

Banana crop presents rapid growth and high fruit production, demanding intense fertilization, with nitrogen and potassium being the most outstanding nutrients. However, national productivity is still low, indicating the need for studies to improve the performance of this fruit. Thus, the objective of this work was to evaluate the productivity and fruit characteristics of Thap Maeo banana, second cycle, under nitrogen and potassium fertilization. Plants of the cultivar Thap Maeo were used in spacing of 2.5 m x 2.5 m. The experimental design was in randomized blocks in a 2 x 4 factorial scheme with three replicates. The combination of presence (400 kg ha-1) or absence of nitrogen and four doses of potassium (0, 300, 600 and 900 kg of K2O ha-1) composed the treatments. It was observed that the application of K2O at the best doses gave gains of 8.5; 5.9; 16.3; 50.2; 20.0 and 27.6%, respectively, for the hands per bunch, fruits per hand, fruits per bunch, fruit diameter and fruit length, and fruit yield, when compared to the control. It was concluded that the use of nitrogen in association with K2O influences in isolation the number of hands per bunch and fruits per bunch, increasing their values. The variables hands per bunch, fruits per hand, fruits per bunch, fruit diameter, length and yield were benefited by the application of K2O, and the best doses were in the range of 502.7 to 658.0 kg ha-1.

IMPACT OF FOLIAR APPLICATION OF POTASSIUM SULPHATE ON WEED DYNAMICS AND SOME PHYSIOLOGICAL ATTRIBUTES OF RAINFED BREAD WHEAT

An experiment to find out the wheat growth as affected by foliar application of potassium Sulphate (K2SO4) on different growth stages under rainfed conditions was conducted at the Agricultural Research Institute, Dera Ismail Khan, Pakistan. Potassium doses viz. 0, 12, 18, 24, 30 and 60 kg ha-1 were applied in foliar form at tillering, booting and heading stages of wheat. The course of study revealed that foliar application of K2O in booting stage produced maximum leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), net photosynthesis rate (NPR) and grain yield, while its application at heading stage produced maximum net assimilation rate (NAR). Among different doses, the application of potassium at the rate of 60 kg ha-1 potassium at the rate of 60 kg ha-1 produced maximum growth and yield and its components during two consecutive cropping seasons of wheat crop while weed density (m-2), relative weed density (%), fresh weed biomass (g m-2) and dry weed biomass (g m-2) influenced non-significantly for both the years. These findings suggest that foliar application of potassium sulphate @ 60 kg ha-1 along with recommended dose of nitrogen (120 kg ha-1) and phosphorus (90 kg ha-1) is the most suitable for successful wheat production under rainfed conditions.

Investigation on Current Status of Rice Fertilization in the Plain Area of Hanzhong Basin

Scientific fertilization is the key to obtain a high-yield and good quality rice. In order to understand the present situation of rice fertilizer application in the Plain Area of Hanzhong Basin, a survey had been conducted. The investigation results showed that: in the Plain Area of Hanzhong Basin, N application was more higher, P2O5 application was reasonable and K2O application was a little lower. Fertilization was very unbalanced and the application rates were quite different among farmers. The base to dressing ratio was unreasonable. All the P2O5, K2O and most of N were applied as base fertilizer, and only a few farmers use top dressing N fertilizer. In the frame of fertilizer variety, there is a phenomenon that using more ammonium bicarbonate than formula fertilizer, using more chemical fertilizer than organic fertilizer and using more macro element fertilizer than trace fertilizer.

Yield gap and production constraints of mango (Mangifera indica) cropping systems in Tianyang County, China

Mango is an important cash crop in the tropics and subtropics. Determining the yield gap of mango and production constraints can potentially promote the sustainable development of the mango industry. In this study, boundary line analysis based on survey data from 103 smallholder farmers and a yield gap model were used to determine the yield gap and production constraints in mango plantations in the northern mountain, central valley and southern mountains regions of Tianyang County, Guangxi, China. The results indicated that the yield of mango in three representing regions of Tianyang County, Northern Mountains, Central Valley and Southern Mountains, was 18.3, 17.0 and 15.4 t ha−1 yr−1, with an explainable yield gap of 10.9, 6.1 and 14.8 t ha−1 yr−1, respectively. Fertilization management, including fertilizer N, P2O5 and K2O application rates, and planting density were the main limiting factors of mango yield in all three regions. In addition, tree age influenced mango yield in the Northern Mountains (11.1%) and Central Valley (11.7%) regions. Irrigation time influenced mango yield in the Northern Mountains (9.9%) and Southern Mountains (12.2%). Based on a scenario analysis, the predicted yield would increase by up to 50%, and fertilizer N use would be reduced by as much as approximately 20%. An improved understanding of production constraints will aid in the development of management strategy measures to increase mango yield.

Investigating the effect of biochar on the potential of increasing cotton yield, potassium efficiency and soil environment

Potassium (K) is an essential macronutrient for plant growth and development. However, in China, available K is relatively low in the soil, and with the extensive use of chemical fertilizer, K use efficiency is constantly reducing, and consequently increasing the potential risk of environmental pollution and economic loss. Therefore, it is essential to reduce the negative impact of over-fertilization on the environment to obtain optimal crop yield. Biochar as a soil amendment has been applied to improve soil fertility and increase crop yield. However, the effects of successive biochar application on cotton yield, agronomy efficiencies and potash fertilizer reduction are not well documented. Our results of a pot experiment showed that the application of 1% biochar to soil under different K levels significantly improved dry mass accumulation and K content of different plant parts, and increased the number of buds, bolls and effective branches of cotton. Particularly, plants treated with 150 mg/kg K2O and 1% biochar had the highest growth parameters. The most important characteristics including the harvest index, K fertilizer contribution index, partial factor productivity, agronomic efficiency and apparent recovery efficiency of K under C1 (1% biochar) were generally greater than those under C0 (without biochar). The 75 mg/kg K2O application was optimal to produce the highest yield with 1% biochar, demonstrating that biochar can increase cotton yield and therefore, reduces chemical K fertilizer application and alleviates agricultural environment risks of chemical fertilizer.