Ca Fertilization Research Articles

Calcium fertilization on the Phalaenopsis ssp. cultivation (Orchidaceae)

The cultivation efficiency and quality improvement of Phalaenopsis sp. production through mineral nutrition has been widely studied. The objective of this study was to evaluate the effects of different concentrations of calcium (Ca) in the nutrient solution on the growth, nutrient uptake, and overall health of Phalaenopsis sp. Seedlings obtained from in vitro propagation at 6 months of age were fed biweekly with a nutrient solution suggested by Hoagland and Arnon with modified Ca concentrations of 0 mM, 1.25 mM, 2.5 mM, 5 mM, 7.5 mM, and 10 mM. After 24 months, characteristics such as number of leaves, width and length of the largest leaf, total leaf area, dry mass of leaves and roots, leaf texture, and number and dry mass of flowers were evaluated. Macronutrient content was determined from leaf dry mass. Substrate pH and electrical conductivity were also measured. Increasing Ca concentrations up to 6.25 mM improved leaf length, total leaf area, number of flowers and flower dry mass. Leaf texture and electrical conductivity of the substrate increased up to a Ca concentration of about 2.5 mM. Leaf nitrogen and phosphorus contents increased with higher Ca concentrations. Optimal Ca fertilization at 6.25 mM had positive effects on both vegetative and reproductive growth, with no visual symptoms of Ca deficiency observed during vegetative development. These results emphasize the importance of precise and tailored nutrient management, not only to avoid hidden deficiencies, but also to maximize the quality and commercial value of Phalaenopsis sp. plants.

Impacts of Various Calcium Concentrations on the Biochemical Characteristics of Corn (Zea mays L.) Seedlings in Drought Conditions

ABSTRACT In recent years, there has been a significant decrease in corn production and quality due to drought. Ca applications are thought to be effective in eliminating this negative effect of drought. The research was conducted in a climatic chamber using a completely randomized experimental design. Four Ca doses were used in this study as research factors. In the study, increases in malondialdehyde, catalase activity, and superoxide dismutase levels, as well as leaf proportional water content, membrane damage index, Ca, and potassium contents, were examined. As a result of the research; leaf proportional water content was 55.633–72.103%, membrane damage index 44.540–71.643%, K content 1.967–2.733%, Ca content 0.243–0.497%, malondialdehyde activity 0.090–0.114 nmol g−1 FW, catalase activity 0.015–0.043 nmol g−1 FW and superoxide dismutase varied between 0.011 and 0.027 unit g−1 FW. Drought stress has negative effects on yield and quality properties in crop production. It has been determined that these negative impacts vary depending on the genetic structure of the plants as well as the presence of regulatory elements such as Ca. In this research, it was determined that Ca fertilization under drought stress caused a decrease in K content and some enzymatic activities such as MDI, MDA, CAT, and SOD, and an increase in LWC and Ca contents in corn seedlings. As a result, it is concluded that the applied Ca doses reduced the negative effects of drought. In conclusion, the 400 mg L−1 Ca application is recommended for reducing the negative effects of drought stress.

Evaluation of the Seed Quality and Fatty Acids Composition of Groundnut (Arachis Hypogaea L.) in Response to the Conventional and Nano Forms of Zn and Ca Based Fertilizers

ABSTRACT The application of zinc (Zn) and calcium (Ca) fertilizers is necessary to improve quantitative and qualitative yield of groundnut. This study was done to evaluate seed yield and the fatty acids composition of groundnut (Arachis hypogaea L.) in response to the different forms of Zn- and Ca-based fertilizers. This experiment is carried out as a split plot arrangement based on randomized complete block design with three replications in Rasht, Iran, during the 2018 and 2019 cropping seasons. The four levels of Zn fertilizers including without fertilizer application (control), Zn Nano-fertilizer (Zn-Nano), Zn-EDTA, and Zn-sulfate (ZnSO4) as the main plot and the four levels of the Ca fertilizers including Ca Nano-fertilizer (Ca-Nano), Ca-EDTA, Ca-chloride (CaCl2), and Ca-nitrate [Ca(NO3)2] as the sub-plot comprised experimental treatments. The greatest pod number per plant (PNP) (38.78), 100-seed weight (100-SW) (61.49 g), seed yield (SY) (2790 kg/ha), biological yield (BY) (9303 kg/ha), seed oil content (SOC) (52.34%), oil yield (OY) (1625 kg/ha), protein yield (PY) (673 kg/ha), oleic acid (OA) (57.30%), and linoleic acid (LA) (30.97%) were obtained in response to Zn and Ca nanofertilizers. The combined application of Zn and Ca nanofertilizers enhanced the SY of groundnut via increasing of PNP and 100-SW indices and improved the groundnut oil quality due to the increment of OA and LA under regional climatic conditions. Hence, Zn and Ca nanofertilizers showed superiority for the quantity and quality of groundnut yield and could be recommendable to enhance the quantitative and qualitative yield of groundnut under similar climatic conditions.

Effect of Calcium Fertilization on Calcium Uptake and Its Partitioning in Citrus Trees

Calcium (Ca) plays a vital role as a macronutrient in the growth and development of plants. In order of decreasing solubility, Ca can be found in vegetal tissues as soluble Ca (Fraction I), bound Ca (mainly pectates, Fraction II), inorganic insoluble Ca (mainly phosphates and carbonates, Fraction III) and organic insoluble Ca or oxalate (Fraction IV). To explore the impact of Ca fertilizer application on plant growth and its allocation among different fractions, young citrus trees were fed over a complete vegetative cycle with a 44Ca labeled fertilizer (T1-Ca), while control plants (T2) received no Ca fertilizer. The results showed that plants receiving Ca exhibited significantly greater biomass. 44Ca derived from the fertilizer was localized mainly in sink organs (new flush leaves–twigs and fibrous roots). The primary fraction responsible for total Ca partitioning was Fraction II, followed by Fraction III or IV. Citrus plants, commonly found in calcareous soils, demonstrated improved growth with calcium treatments, indicating a positive link between calcium supplementation and enhanced development. The calcium supplied through the fertilizer (44Ca) was predominantly concentrated in sink organs (mainly in Ca-pectate fraction), including new flush leaves and twigs above ground, as well as fibrous roots below ground.

Seasonal differences in yield and fertilizer use efficiency of different low-calcium-tolerant peanut varieties in response to the timing and splitting of calcium application in southern China

Soil Ca deficiency hinders the development of the peanut industry, and inappropriate Ca fertilizer application increases the risk of soil environmental degradation and reduces the fertilizer utilization rate and yield in peanuts. N fertilizer doses are frequently split and applied over different time periods. However, whether this widespread method is applicable to Ca fertilizer and improves peanut growth and yield in southern China requires further investigation. Thus, this study evaluated the effects of timing and splitting Ca applications on the dry matter accumulation and partition, fertilizer use efficiency, and yield of different low-Ca-tolerant peanut varieties (low-Ca-sensitive Jihua 16 and low-Ca-tolerant Yueyou 45) in the early and late seasons. The results showed that the early timing and splitting of Ca application significantly increased the pod yield of Jihua 16 by increasing nitrogen and calcium use efficiencies, dry matter accumulation, and assimilate transfer from vegetative parts to the pods in both years. The highest pod yield of Jihua 16 was obtained with 300 kg CaO ha−1 basal application before sowing and 300 kg CaO ha−1 top-dressing application at the flowering stage (B300:T300) in the early season and 600 kg CaO ha−1 basal application before sowing and 600 kg CaO ha−1 top-dressing application at the flowering stage (B600:T600) in the late season; the yields were significantly increased by 91.87 % in 2020, 92.15 % in 2021, and by 255.36 % in 2020, 248.22 % in 2021, respectively, compared with those obtained with no Ca fertilizer use. However, the Ca treatments did not significantly affect pod yield or the related parameters of Yueyou 45 in either season. The pod yield of both cultivars was higher in the early season than that in the late season because of the higher effective accumulated temperature and precipitation during the reproductive stage in the early season of both years. The results of this study indicate that the early season is most suitable for peanut production, and the B300:T300 and no Ca application strategies are appropriate for the Ca-sensitive and -tolerant cultivars, respectively, in the early season in southern China. Notably, additional Ca-tolerant cultivars should be selected for cultivation in southern China to reduce future fertilizer application. These results provide useful information for improving double-cropping systems, Ca fertilization strategies, and peanut cultivar breeding in southern China.

Calcium fertilization strategy to improve production and quality of ‘Tommy Atkins’ mango in semi-arid conditions

ABSTRACT Calcium (Ca) is an essential element for the development of mango plants. New technologies are emerging in the market to assist the production process, such as organic acids and amino acids. The objective of this study was to evaluate the effect of different strategies of Ca fertilization on the production and physical-chemical quality of ‘Tommy Atkins’ mango grown under Brazilian semi-arid conditions. The experiment was carried out in two commercial mango orchards, following a randomized block design, with four replications and four plants per block. The factorial design was composed by three formulations of Ca-based products and three forms of application. Fruit were harvested at the physiological maturity to determine yield and quality. There was no statistical difference among treatments for the incidence of internal physiological disorders in mangoes, with mean values ranging from 0.08% to 0.38%. Fruit production and physical-chemical quality were affected by the different Ca formulations and forms of application. Fruit production ranged from 21.5 to 44.4 kg per plant. The Ca foliar application plus fertigation in the form of CaCl2.2 H2O resulted in higher production, as well as higher fruit weight and lower weight loss at 40 days after harvest.

Role of soil nutrient elements transport on Camellia oleifera yield under different soil types

BackgroundMost of Camellia oleifera forests have low fruit yield and poor oil quality that are largely associated with soil fertility. Soil physical and chemical properties interact with each other affecting soil fertility and C. oleifera growing under different soil conditions produced different yield and oil composition. Three main soil types were studied, and redundancy, correlation, and double-screening stepwise regression analysis were used for exploring the relationships between C. oleifera nutrients uptake and soil physical and chemical properties, shedding light on the transport law of nutrient elements from root, leaves, and kernel, and affecting the regulation of fruit yield and oil composition.ResultsIn the present study, available soil elements content of C. oleifera forest were mainly regulated by water content, pH value, and total N, P and Fe contents. Seven elements (N, P, K, Mg, Cu, Mn and C) were key for kernel’s growth and development, with N, P, K, Cu and Mn contents determining 74.0% the yield traits. The transport characteristics of these nutrients from root, leaves to the kernel had synergistic and antagonistic effects. Increasing oil production and unsaturated fatty acid content can be accomplished in two ways: one through increasing N, P, Mg, and Zn contents of leaves by applying corresponding N, P, Mg, Zn foliar fertilizers, while the other through maintaining proper soil moisture content by applying Zn fertilizer in the surface layer and Mg and Ca fertilizer in deep gully.ConclusionSoil type controlled nutrient absorption by soil pH, water content and total N, P and Fe content. There were synergistic and antagonistic effects on the inter-organ transport of nutrient elements, ultimately affecting N, P, K, Cu and Mn contents in kernel, which determined the yield and oil composition of C. oleifera.

Transfer of 137Cs and 90Sr from soil-to-potato: Interpretation of the association from global fallout in Aomori to accidental release in Fukushima and Chornobyl

Ceasium-137 and 90Sr are major artificial radionuclides that have been released into the environment. Soil-to-plant transfer of radionuclides is an important route to food contamination. The radionuclide activity concentrations in crops must be quantitatively predicted for estimating the internal radiation doses from food ingestion. In this study, soil and potato samples were collected from three study sites contaminated with different sources of 137Cs and 90Sr: Aomori Prefecture (global fallout) and two accidental release areas (Fukushima Prefecture and the Chornobyl exclusion zone). The 137Cs activity concentrations in the soil and potato samples widely ranged from 1.0 to 250,000 and from 0.048 to 200,000 Bq kg−1 dry weight, respectively. The soil-to-potato transfer factor of 137Cs also ranged widely (0.0015–1.1) and decreased with increasing concentration of exchangeable K. Meanwhile, the activity concentrations of 90Sr in the soil and potato samples were 0.50–64,000 and 0.027–18,000 Bq kg−1 dry weight respectively, and the soil-to-potato transfer factor of 90Sr was 0.023–0.74, decreasing with increasing concentration of exchangeable Ca. The specific activity ratios of 137Cs/Cs and 90Sr/Sr in the exchangeable fraction were similar to those in potatoes, with a factor of 3 in the ±95 % confidence intervals over six orders of magnitude and a factor of 2 in the ±95 % confidence intervals over five orders of magnitude, respectively. According to the data, the accuracy of predicting the activity concentrations of 137Cs and 90Sr in potatoes can be improved by applying the specific activity ratios of 137Cs/Cs and 90Sr/Sr in the exchangeable fraction. This approach accounts for variable factors such as the effects of K and Ca fertilization and soil characteristics. It also emphasizes the benefit of determining the stable Cs and Sr concentrations in potatoes and other crops prior to possible future contamination.

Effect of foliar calcium and nitrogen treatments on yield and fruit quality of table grapes cv. ‘Cardinal‘

The foliar fertilization has been used as an important agrotechnical measure to avoid deficiencies and to improve quality. During the three consecutive years, a study has been performed on Vitis vinifera L. (cv. ‘Cardinal’) to examine whether a yield and grape berry quality have been affected by the foliar application of Ca and N fertilizers. A liquid mineral fertilizer containing 40% Ca(NO₃)₂ as Variant I and 31% N with 0,015 % Fe-chelate; 0,01 % Mg – chelat as Variant II (in text) has been sprayed four times during the growing period (before and after blooming, buckshot berries, and verasion). Results showed that foliar application of calcium and nitrogen increased the yield of table grapes in all three years of research, in comparison with a control variant. The highest yields of grapes in all three years of investigations were achieved in Variant II – 4.57 kg/vine (14.85 t/ha). During the tree years of investigations, the largest mass of grape bunch and berries were recorded in Variant II (382g and 368.68g), while the lowest cluster weight was in the control variant (344g and 330.92g). With a reference to the mechanical properties of the grape berries, the highest resistance to pressure (2229.70g) and breaking resistance (364.52g) were found in Variant I, treated with Ca fertilizer. The foliar application significantly affects the mechanical properties (resistance of the berry to pressure and breaking), especially in Variant I. The application of different types of foliar fertilizers did not have any significant effect on sugar contents and total acids, compared with the control variant.

Changes in solubility and chemical speciation of potassium, calcium, and silicon in wood ash by acid treatment

ABSTRACT This study investigated the relationship between the solubility and the chemical speciation of plant nutritional elements (K, Ca, and Si) in wood ash treated with a dilute solution of sulfuric acid or phosphoric acid. The diluted acid solutions were added to fly ash (FA) collected from a power plant, and the untreated and acid-treated FAs were analyzed for their contents of K, Ca, and Si. The crystalline phases of the untreated and acid-treated FAs were identified using X-ray diffraction (XRD), and the Si species were determined using X-ray absorption near-edge structure (XANES) spectroscopy. Sulfuric acid and phosphoric acid treatments did not affect the solubility of K in FA. Water soluble and citrate soluble K in FA were decreased by the addition of these acids. The water soluble Ca content in FA treated with phosphoric acid did not show a significant change compared to that in the untreated FA, but it increased up to 65 times in FA treated with sulfuric acid. It is suggested that CaCO3, which was the main Ca species in the untreated FA, was transformed into syngenite and gypsum by the sulfuric acid treatment. Hydrochloric acid soluble Si in the acid-treated FA decreased compared to that in the untreated FA. In contrast, the NaOH-soluble Si fraction, a method for selectively extracting silica gel, increased especially in the phosphoric acid-treated FA. The results of XANES analysis showed that the FA samples treated with 10–30% sulfuric acid or 10–30% phosphoric acid had a lower degree of Si polymerization than the untreated FA, which corresponded generally to the increased Si solubility in FAs. However, FA treated with 30% sulfuric acid had lower soluble Si despite a lower degree of polymerization than FA, which was attributed to a lower pH. These results suggest that the change in solubility of Si in the acid-treated FA was influenced by the degree of polymerization and the decrease in pH. From the viewpoint of a fertilizer use of FA, sulfuric acid-treated ash, which consists of both water soluble Ca and citrate soluble Ca, is suitable for Ca fertilizer, and phosphoric acid-treated ash, which has high NaOH-soluble Si, is suitable for Si fertilizer

Analysis of leaf forage value and screening of different populations of Pteroceltis tatarinowii, a rare and endemic species in China.

To fully exploit the economic value of the Chinese endemic species Pteroceltis tatarinowii and provide new resources for forage production, the forage nutritional value of P. tatarinowii leaves from different populations was analyzed and evaluated. The results were as follows: 1) There were significant differences in the forage nutrient indices of leaves from different populations. The crude protein content was 10.77%-18.65%, with an average of 14.58%, and the SDJN population had the highest crude protein content. The average crude fat, crude fiber content was 7.62%; the average neutral detergent fiber content was 25.33%; and the average acid detergent fiber contents were 6.79%, 7.62%, 25.33%, and 17.52%, respectively. The average phosphorus and calcium content in the leaves was 0.785 g·kg-1 and 58.01 g·kg-1, respectively. The tannin content was much lower than the antifeedant standard, at an average of 4.97 g·kg-1. The average total amounts of hydrolyzed and free amino acids in the leaves were 108.20 mg·g-1 and 47.87 mg·g-1, respectively. Thus, P. tatarinowii leaves have high crude protein, crude fat, and calcium contents, and low fiber, tannin contents, and are protein-rich. These results provide evidence that this species can be developed into an excellent woody forage tree. 2) There were significant differences in the forage quality evaluation indices among the populations. The forage indices of NDP, ADP, DMI, DDM, and RFV of 21 populations all met the super standard of the American Grass and Grassland Association (AFGC) for hay, two crude protein indices met the grade 1 standard, and 12 crude protein indices met the grade 2 standard. Four high-protein and high-RFV forage populations (SDJN, SDZZ, SXLQ, and AHXX) were selected. 3) The results of the correlation analysis showed that there was no significant correlation between the forage characteristics of P. tatarinowii leaves and latitude and longitude, indicating no significant geographical variation. However, the forage characteristics were strongly correlated with elevation, average annual temperature, and annual precipitation. Thus, high elevation, low temperatures, and rainy weather can improve the forage value of the leaves. P. tatarinowii can be planted to provide leaf forage in cold and wet areas at a specific elevation. Moreover, the forage value of P. tatarinowii leaves can be further improved by increasing nitrogen fertilizer and reducing K and Ca fertilizers during cultivation. 4) Cluster analysis revealed obvious regionalism. Taking the Yangtze River Basin as the limit, cluster analysis divided the species into four population groups: the Yangtze River Basin and northern, southwestern, and eastern coastal populations.

Inoculation with arbuscular mycorrhizal fungi increase calcium uptake in Malus robusta

Utilization of plants-microbe's interactions to remediate calcium11Ca: calcium (Ca) deficiency soils is effective and practical. A greenhouse pot experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi22AMF: arbuscular mycorrhizal fungi (AMF) inoculation and the synergy of AMF and Ca fertilizer on physiological and transcriptomic responses in apple rootstock (Malus robusta) roots. AMF and Ca fertilizer synergistically served to elongate root length, surface area, average stem diameter and biomass, such extended the surface area in contact with soil nutrients and water. Symbiosis of AMF with apple seedlings made significantly higher levels of Ca in root tissue and promoted Ca translocation from roots to shoot tissue. GO and KEGG pathway analysis disclosed that gene expression varies in several critical gene families, such as auxin response (MdAux/IAAs, MdGH3 and MdSAUR), TCA cycles (MdCS, MdMDH and MdACO), phosphate transporters (MdPHT1;1, MdPHT1;10 and MdPHT1;3) and Ca2+ signal transduction pathways (MdCa2+/ATPase, MdCML, MdTPC1 and MdCDPK), indicating that apple regulates the expression of genes related to auxin synthesis, organic acid secretion, and calcium transporters and channels, thereby increased the growth of apple roots and promoted the secretion of organic acids, resulting in the increase of calcium effectiveness in soil. AMF promoted the accumulation and utilization of Ca in plants by regulating the expression levels of genes related to these pathways. These results contribute to a better understanding of AMF symbiosis mechanism behind the Ca uptake of apple seedlings under exogenous Ca treatment.

Silicon and calcium controls on iron and aluminum mobility in Arctic soils

Arctic permafrost soils store large amounts of organic carbon and nutrients. With deepening of the perennial thawing upper active layer due to rising temperatures in the Arctic, not only the mobility of organic matter (OM), but also those of elements like silicon (Si) or calcium (Ca) may increase. It is known that major elements like Si and Ca can affect mineralization rates of OM, consequently influencing the carbon cycle. But only little is known about the interactions of Si and Ca with inorganic nutrients like iron (Fe) or potentially toxic elements like aluminum (Al) in Artic soils. In this study, we analyzed the effect of Si and Ca fertilization in laboratory incubation experiments with soil samples from several Arctic regions. Our results show a significant increase in Fe and Al mobility (Mehlich-3 extractable) after increasing Si. Using high resolution X-ray microscopy (STXM/NEXAFS), we show that Si promotes Fe(II) phases and by this increases Fe mobility. Al mobility was increased for acidic and neutral pH soils but decreased for alkaline soils after increasing Si. Furthermore, we show a decreased Al mobility after increasing Ca, independent on the original pH values and the OM content of the soils. These results demonstrate the importance of interactions between Si and Ca on one hand and Fe and Al mobility on the other hand for Arctic soils.

Exogenous Calcium Induces Different Hydraulic Strategies in Response to Osmotic Stress in Maize Seedlings.

Recent discoveries regarding the signal molecules involved in abiotic stresses require integration into the field of plant hydraulic property research. Although calcium (Ca) is an important second messenger involved in numerous complex, abiotic stress-induced signaling pathways, it remains unclear how exogenous calcium mediates cellular signaling to promote plant drought resistance. We investigated the effects of calcium on the water balance and hydraulic properties in maize seedlings (Zea mays L.) under osmotic stress simulated by 10% (m/v) PEG-6000 in a hydroponic culture. The osmotic stress dramatically decreased the photosynthetic rate, transpiration rate, stomatal conductance, leaf water content, and root water absorption. However, the short-term (2 h) and long-term (10 d) exogenous Ca2+ (CaCl2: 10 mM) treatments had different effects on the maize gas exchange parameters and leaf water status. The short-term treatment improved the leaf transpiration by inhibiting the abscisic acid (ABA) synthesis and accumulation in the leaves, generating a stronger transpiration pull and enhancing the root water absorption and axial flow path water transport by increasing the root hydraulic conductance to relieve the osmotic stress-induced inhibition. The long-term treatment induced the ABA and H2O2 accumulation in the roots and leaves. Under osmotic stress, the accumulation of ABA, H2O2, and Ca2+ rapidly repressed the transpiration and enhanced the radial flow path water transport, decreasing the water loss and improving the stress tolerance. These insights suggest a role for a judicious use of Ca fertilizer in reducing the adverse effects of drought on agricultural production.

Optimal Soil Calcium for the Growth of Mulberry Seedlings Is Altered by Nitrogen Addition

Increasing soil N not only aggravates calcium (Ca) stress by stimulating Ca leaching from the soil but also impacts the sensitivity of plants to Ca stress. However, how increasing N influences the soil Ca demand of seedlings is largely unknown. We studied the influence of different concentrations of exogenous Ca (i.e., 0, 200, 400, 600, and 800 mg⋅kg−1 Ca2+) on the growth, photosynthesis, Ca absorption, and intrinsic water use efficiency (iWUE) of mulberry (Morus alba) seedlings under two N levels (i.e., 200 and 600 mg⋅kg−1 NH4NO3). We found that there was an optimal concentration of soil Ca for the growth and net photosynthetic rate (Pn) of mulberry seedlings; the optimal Ca concentration was 200 mg⋅kg−1 under low N conditions and 400 mg⋅kg−1 under high N conditions. Therefore, the application of N fertilizer increased the optimal Ca concentration. Different from the unimodal relationship between biomass and Ca levels, the iWUE of mulberry was significantly and positively correlated with soil Ca levels. At the same time, except under the 800 mg⋅kg−1 Ca treatment, the soil Ca levels were reflected by foliar Ca concentrations. The N deposition, large-scale N fertilizer application, and drought increase Ca demand in plants, thus causing the application of Ca fertilizer to be necessary in low-Ca soil while alleviating Ca stress in high-Ca soil. The balance between the optimal Ca level needed for growth and drought resistance should be considered when determining the amount of Ca fertilizer required.

Produção e qualidade de hastes florais de gérbera em substrato suplementado com diferentes doses de nitrogênio e cálcio

Abstract Success in production and quality of gerbera flower stalks over time depends on environmental factors and on appropriate fertilization procedures. The objective of the present work was to evaluate the production and quality of flower stalks of gerberas as cut flower cultivated for 28 months (with 25 months of harvest) in a pine bark-based substrate supplemented with different doses of nitrogen and calcium. The experiment was conducted in a greenhouse. Three doses of nitrogen (N) (0.07 g, 0.15 g and 0.20 g L-1 substrate) and three doses of calcium (Ca) (0.02 g, 0.03 g and 0.04 g L-1 substrate) were applied every 15 days along the cultivation period. The control was considered an additional treatment to which neither N nor Ca was supplemented to the plants in the pots. Highest flower yields and best flower quality were obtained in months in which the temperatures were in the range of 20 ºC to 25 ºC. The highest number of floral stalks and the largest diameter of the capitulum had a significant quadratic adjustment according to N doses. The maximum values were obtained with 0.14 g of N L-1 substrate. Whereas for Ca fertilization, a significant positive linear adjustment was determined, i.e., the highest values were obtained with the highest dose (0.04 g Ca L-1 substrate). There was a monthly variation in the yield and quality of cut gerberas grown in commercial substrate based on pine bark regardless of the different doses of nitrogen and calcium used in the experiment.

Anatomical characteristics of cocoa plant roots as affected by the levels of calcium fertilization

Cocoa plant (Theobroma cacao L.) is one of good annual crops grown in Indonesia. The disadvantages and advantages of Ca in plants can affect morphology and anatomy in plants. This research aimed to identify the effect of Ca on the anatomical performance of the roots of cocoa plants and determine the optimal dose of Ca for the anatomical characteristics of the roots of cocoa plant. The research was conducted at the cocoa plantation owned by PT. Pagilaran at North Segayung Production Unit, Tulis Subdistrict, Batang Regency, Central Java, in October 2019 – February 2021. The observation of root anatomy was carried out by making preparations, and the plant roots were taken destructively and sliced transversely. The field experiment was arranged using a single factor randomized complete block design. The treatments consisted of without fertilizer application and calcium fertilization at a dose of 100 g/tree/year, 200 g/tree/year, 300 g/tree/year, and 400 g/tree/year. The cocoa clone used was clone RCC 71. The results showed that an increase in the dose of CaCl2 fertilizer up to 400 g/tree/year was generally followed by an increase in the size of the xylem and phloem diameters, the thickness of the cork layer, the thickness of secondary cortex, and the diameter of the stele. The quadratic effect of the dose of CaCl2 fertilizer was observed only on the thickness of the root cambium tissues. Thus, it is necessary to conduct further research to determine the optimal dose of Ca fertilizer for the anatomical characteristics of cocoa roots.

Absorption and Distribution of Calcium (45Ca) Applied to the Surface of Orange (Citrus sinensis) Fruits at Different Developmental Stages

In this study, the rate of absorption and transport of calcium (Ca) in orange fruits (Citrus sinensis cv. Fukumoto) after surface treatment with 45Ca was evaluated by supplying treatments at different dates between fruit set and mid-phase II of growth (i.e., 30, 44, 66 and 99 days after full bloom, DAFB). 45Ca absorption was always detected, but 45Ca application at the fruit set was associated with the highest rates of Ca transport into the pulp (39%) compared to the other treatments (17–19%). Scanning electron microscopy SEM) images of the fruit surface showed the occurrence of stomata along with the entire rind at all the developmental stages evaluated. However, from the beginning of stage I, stomata began to collapse and develop plugs, and this became frequent as the fruit age increased. From 44 DAFB, oil gland density increased, and Ca oxalates (CaOx) were found in the fruit flavedo and albedo. Fruit Ca (not labeled) concentration increased from fruit set (30 DAFB) to 99 DAFB, although oil gland formation and rind growth and differentiation likely hindered Ca transport to internal fruit tissues (pulp). The total Ca concentration in the pedicel was always higher than that in the fruit, with no differences between the first three treatments. The information obtained in this study may be essential for improving Ca fertilizer efficacy in citrus by spray applications.

Calcium applications on ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees: fruit quality at harvest and after cold storage

The aim of this study was to evaluate the effect of new Ca sources sprayed on ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees on nutrient levels in leaves and fruit, as well as on fruit ripening features and quality at harvest time and after cold storage. Experiments were carried out in a commercial orchard planted with ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees in Caçador, Santa Catarina state, Brazil. Application of different Ca sources and untreated trees were evaluated in each experiment. Fruit were harvested at two different ripening stages and analyzed based on the following variables: fruit ripening at harvest time, as well as fruit quality and incidence of physiological disorders after 210-day storage at 1 °C. Calcium applications did not change Ca levels in the leaves and of the whole fruit. Calcium levels in fruit peel increased in cultivars Maxi Gala and Fuji Suprema due to leaf Ca applications. ‘Maxi Gala’ apples recorded higher postharvest incidence of physiological disorders, such as greater loss of fruit firmness than ‘Fuji Suprema’ apples (Due to 1-methylcyclopropene [1-MCP] application on ‘Fuji Suprema’ apples). Calcium applications did not change fruit maturation (starch index and pulp firmness) or apple pulp firmness preservation in both cultivars, although they reduced the incidence of bitter pit disorder in ‘Maxi Gala’ apples. The new sources of Ca tested did not increase Ca contents, nor did they reduced the risk for physiological disorder compared to the standard CaCl2 treatment that has been commercially used for decades as the main Ca fertilizer.

Study on the Effect Difference of Two Kinds of Control Techniques on Cracking Fruit of Qingcui Plum

In this experiment, Qingcui plum in Xuanhan County of Dazhou City was used as the material. Aiming at the problem of fruit cracking, the cracking rate of different prevention measures was investigated by surface mulching, root irrigation, and foliar spraying of three different Ca fertilizers. The cell growth rate and cell wall composition were determined. The results showed that surface mulching and foliar spraying had significant effects on reducing fruit cracking rate; root irrigation greatly aggravating fruit cracking; the effect of foliar spraying calcium glycol was significantly better than that of foliar spraying calcium nitrate and calcium amino acid. During the second rapid fruit expansion period, the growth rate of pulp cells was always higher than that of pericarp cells, the pectin content of the fruit showed a downward trend, and the pectin content of the cracked fruit was significantly lower than that of the normal fruit; the cellulose content of the cracked fruit was significantly lower than that of the normal fruit. Therefore, the fruit cracking may be caused by the uncoordinated growth of pulp and peel, and the lack of pectin and cellulose.