Calcium Sprays Research Articles

Spray-pyrolyzed hydroxyapatite thin-film coatings

Hydroxyapatite (HA) thin-film coatings have been deposited on sheet substrates of a commonly used biomaterial (Ti6Al4V) using the spray pyrolysis technique. For this, a 0.042 M calcium spraying solution was prepared by dissolving calcium acetylacetonate hydrate in N,N-dimethylformamide, and phosphoric acid (H 3PO 4) was used as the source of phosphorous with different volume concentrations in deionized water. Both the solutions were supplied simultaneously and in parallel during the deposition of the coatings. The coatings were deposited at substrate temperatures of 425 and 525 °C. The use of 0.27% (volume) solution of H 3PO 4 resulted in coatings with stoichiometry close to that of the HA. The chemical composition, surface morphology and structure of the HA coatings were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The characteristics of the coatings thus observed are presented and discussed. The high purity of the coatings was revealed by XPS, confirming the presence of Ca, P and O as the main constituents, with a Ca/P ratio of about 1.3. Some carbon, inherent to the precursors used, was also detected by XPS. The XRD patterns obtained suggested preferred (113) and (321) crystal orientations in the coatings.

Preharvest calcium sprays were not always needed to improve quality of 'gala' apples in Brazil

Calcium sprays have normally improved both the quality and the storage life of apples throughout the world because Ca helps to prevent many fruit disorders and that taken up from the soil does not often reach the fruit in adequate amounts. Since the efficacy of Ca sprays varies according to soil, apple cultivar, and weather conditions, this study was carried out from 1998 to 2004, in the Southern of Brazil, in order to assess the effect of Ca sprays on the quality and storability of 'Gala' fruits. The experiment was set up in an orchard planted in 1988, on a density of 1234 trees/ha. Treatments consisted of 0, 4, 8, and 12 annual sprays of 0.5% CaCl2 regularly distributed 30 days after petal fall until one week before harvest. Fruits of the same size and maturity level were annually analyzed at harvest and after five months of conventional cold storage (-1ºC and 90-95% of RH). In five out of six seasons, fruits from all treatments were free of any physiological disorder, and Ca sprays had no effect on leaf composition and on any fruit attribute (soluble solids, titratable acidity, starch pattern index, flesh firmness, and concentrations of N, K, Ca and Mg). In the season of 2000/2001, however, when yield was 18 t ha-1 and fruits had an average weight of 175 g, the incidence of bitter pit plus lenticel blotch pit on stored fruits was 24% in the treatment with no calcium sprays and it decreased up to 2% in that with 12 sprays. Two seasons later, yield was also low (25 t ha-1) and fruits were large (168 g each), but they did not show any physiological disorder regardless of the number of Ca sprays. It seems that the incidence of Ca related disorders in 'Gala' apples grown on limed soils in Brazil with no excess of any nutrient only occurs on seasons with low crop yield, as a result of large fruits and a high leaf/fruit ratio, associated with some unknown environmental conditions.

Effect of Pre-Harvest Calcium Sprays on Calcium Concentrations in the Skin and Flesh of Apples

ABSTRACT During 2004 and 2006, experiments were conducted that measured the absorption of calcium (Ca) by the fruit and assessed the effects of Ca sprays on the skin and flesh of apples. Frequent (1 spray/month for 2 or 4 months) Ca treatments increased the concentration of Ca in the skin, but not in the flesh of fruit, and several sprays were needed to promote a prolonged increase in the concentration of Ca in the skin. Calcium sprays did not influence the concentrations of magnesium (Mg) and potassium (K). Foliar analyses confirmed the absorption of topical Ca by the apple tree following the Ca sprays as the concentration of Ca in leaves increased.

Texture and Other Quality Attributes in Olives and Leaf Characteristics after Preharvest Calcium Chloride Sprays

The effect of three preharvest sprays with water or 58.5 mm calcium chloride (CaCl2) on texture and other quality attributes was investigated in ‘Konservolia’ olives harvested at the black-ripe stage and measured after 1 and 15 days of storage in air at 10 °C with 85% relative humidity. Effects on fruit calcium (Ca) and magnesium (Mg) concentrations during the period of spray applications were also studied. Concentrations of Ca, Mg, and chlorophyll and photosynthesis rate in leaves were measured on the day of final fruit harvest. No foliar or fruit toxicity was observed. In leaves, Ca sprays increased Mg but did not affect Ca and chlorophyll concentration and photosynthesis rate. In fruits, Ca sprays prevented the gradual decrease in Ca concentration that occurred in untreated fruits and maintained Mg at constant levels during ripening on the tree but did not affect fruit size and oil content as measured 1 day after storage. Ca-treated fruits were firmer with lower soluble pectin (SP) concentration and higher calcium pectate (CaP) than controls in both storage days, whereas the protopectin levels were similar in all fruits. Results showed positive linear correlation between Ca concentration and either firmness or CaP, whereas that between Ca and SP was negative as found in fruits stored for 1 day. Fruit production rates of carbon dioxide and ethylene, L* and chroma (C*) of peel, and hue angle (h°) of flesh were unaffected either by Ca treatment or storage time. Ca treatment did not affect fruit weight loss, the decreases in peel h° and flesh L*, but increased flesh C* during storage. The results indicate positive effects of preharvest calcium sprays on olive firmness without any negative effect on fruits or leaves.

Calcium-Induced Freezing and Salinity Tolerance in Evergreen Oak and Apple cv. ‘Golden Crown’

Greater variability in weather patterns and later spring frosts equate to poor winter hardiness, premature spring budbreak, and greater susceptibility to low-temperature damage and concomitant deicing salt application. A field trial was undertaken to determine the influence of a range of commercially available calcium fertilizers applied as foliar sprays on the freezing and salinity tolerance of two tree species, evergreen oak (Quercus ilex L.) and apple (Malus cv. ‘Golden Crown’). In all cases, application of calcium sprays increased twig, leaf, and root freezing and salt tolerance of both species as measured by leaf chlorophyll fluorescence and tissue electrolyte leakage bioassays. In the case of apple, a hardiness gain of 4.3°C (7.74°F) was recorded in twig tissue. In the case of evergreen oak, a hardiness gain of 2.1°C (3.78°F) was recorded in leaf tissue. After a –5°C (23°F) (apple) and –6.5°C (20°F) (evergreen oak) freezing stress, root electrolyte leakage values as a measure of cell membrane structural damage were 16% to 27% less in calcium-treated trees compared with noncalcium-treated controls. The salt concentration needed to cause 50% reductions in leaf chlorophyll fluorescence as a measure of photosynthetic efficiency rose by 0.2% to 1.2% in calcium-fertilized trees indicating a positive influence of calcium on enhancing leaf tissue tolerance to salt damage. Differences in the magnitude of freezing and salinity tolerance gained were noticeable between the calcium products used. In general, calcium hydroxide, calcium nitrate borate, and calcium metalosate improved twig, leaf, and root freezing and salt tolerance in both tree species to a greater degree than calcium chloride, calcium sulphate, calcium nitrate, and a calcium–magnesium complex. A significant correlation existed between increased freezing tolerance and internal tissue calcium content. Results of this study indicate that calcium sprays during late summer and fall can increase the freezing and salinity tolerance of evergreen oak and apple during the winter. This should be considered noteworthy for individuals involved in the management of trees in areas subject to subzero temperature fluctuations and/or concomitant applications of deicing salts in the form of sodium chloride.

Effect of foliar fertilization on leaf mineral composition, sugar and organic acid contents of sweet cherry

Influence of a three-year-long foliar fertilization on mineral composition of leaf, content of sugars (glucose, fructose, galactose and sucrose) and organic acids (citric, malic and fumaric acid) of sweet cherry (Prunus avium L.) fruits was studied. The experiment was conducted during 2005-2007 in West Hungary on mature cv. `Germersdorfi 3' grafted on Prunus mahaleb rootstock, planted in 1999. Trees spaced 7 x 5 m, and growing in a calcareous chernozem soil. Trees were foliar-fertilized with potassium (K) as KNO3 and calcium (Ca) as Ca(NO3)2. Potassium spraying was carried out 3 (K1) and 5 (K2) while calcium was applied at 3 (Ca 1), 5 (Ca2) and 6 (Ca3) weeks after full bloom. Beside fruit analysis, complete soil and leaf analysis were done to study the rate of nutrient uptake and its effects on fruit quality. Contents of nutrients of soil and leaf were determined by atomic absorption and spectrophotometric method, while sugars and organic acids in fruit were determined by HPLC. The applied treatments (except K1) had been increasing leaf K significantly compared to the control till ripening. Most of treatments had no significant effect on Ca content of leaf till ripening. From applied treatments only the boron treatments had significant increasing effect on contents of all examined sugars, compared the control. Furthermore, the effect of calcium spraying on the contents of organic acids was significant.

Effect of calcium on cyclamen pedicel elongation

AbstractA greenhouse experiment was conducted to study the effect of calcium (Ca) supply on pedicel growth of Cyclamen persicum “Metis” during flower development. When flower buds started to develop, four foliar spray Ca treatments were applied, including Ca0 (no added Ca as control), Ca(NO3)2, CaEDTA, and CaEDTA+H3BO3. Calcium spray treatments significantly reduced the number of short pedicels. There were 62% of the flowers with short pedicels (i.e., flower height lower than the foliar height) in the control treatment (Ca0). Short pedicels accounted for 23%, 12%, and 10% in the Ca(NO3)2‐, CaEDTA‐, and CaEDTA+H3BO3‐treated plants, respectively. CaEDTA was a more effective Ca source than Ca(NO3)2 for improving cyclamen pedicel elongation and increasing flower numbers. Additional boron (B) supply may have enhanced Ca translocation within the plant. Transmission electron microscopy (TEM) indicated that pedicel‐cell structure was severely damaged in the control plants. Pedicel‐cell damage was greatly alleviated in plants treated with Ca(NO3)2. No symptoms of cell damage were found in the CaEDTA‐ and CaEDTA+H3BO3‐treated plants. Energy‐dispersive X‐ray spectrometer (EDX) analysis confirmed that CaEDTA+H3BO3 and CaEDTA had increased the Ca : O ratios. Therefore, Ca localization in the pedicel cell had a great influence on the pedicel height of cyclamen, and Ca concentration could be a good indicator for undisturbed cyclamen flower development.

CALCIUM SPRAYING ON NUTRIENT CONCENRATION OF LEAF, SKIN, AND FRUIT IN ‘HASS’ AVOCADO

With the objective of studying the effect of Ca(NO3)2, we carried out pre-harvest foliar sprayings in avocado cv. Hass trees using concentrations of 0, 0.3 and 0.5% every fifteen days from the mid September 2003 until early January 2004, resulting in 11 applications. We evaluated nutrient concentration in the leaf, skin and pulp. Results indicated no increase in concentrations of N, P, Km Ca, and Mg in the leaf, skin and pulp during the first year of evaluation. We concluded that the second year presented a Ca increase in skin and pulp, but not in leaf, with residual effect evidence.

Foliar-applied GA3 Advances Fruit Maturity and Allows Off-season Harvest of ‘Hass’ Avocado

Michoacán and Nayarit are, respectively, the largest and second largest avocado-producing states in Mexico. The main harvest of the ‘Hass’ avocado in both states is concentrated during November to December, which saturates the market and reduces the price of fruit and grower income. The goal of this research was to manipulate vegetative and reproductive growth of the ‘Hass’ avocado with properly timed foliar-applied plant bioregulators (PBRs) to shift the date of flowering and harvest to the period before or after the main harvest. Effects of canopy sprays of gibberellic acid (GA3) or prohexadione calcium (a gibberellic acid biosynthesis inhibitor) applied at different stages of tree phenology on inflorescence development, time of anthesis, date of legal maturity for harvest of ‘Hass’ avocado fruit, yield, and fruit size were quantified. No PBR treatment influenced the time of anthesis. A single or double foliar application of GA3 (50 mg·L−1) ≈4 months (July) before the expected date of main harvest (November) resulted in ‘Hass’ avocado fruit reaching legal maturity (mesocarp dry matter 21.5% or greater) 24.8 to 28.2 d earlier than those of untreated control trees with no negative effect on yield or fruit size.

Pre-harvest foliar application of calcium and boron influences physiological disorders, fruit yield and quality of strawberry (Fragaria×ananassa Duch.)

Studies were conducted in ‘Chandler’ strawberry to determine if pre-harvest foliar application of Ca, B or their combination influences physiological disorders, fruit yield and quality or not. For this, treatments consisted of (i) five sprays of calcium as CaCl2 (first spray was performed at the petal fall stage and later at 7 days interval), (ii) three sprays of boron as boric acid (first spray at the beginning of flowering and later at 15 day interval), (iii) combination of (i) and (ii), and (iv) plants sprayed with water served as the control. Results indicated that fruit harvested from plants, which were sprayed either with Ca or Ca + B had significantly lesser incidence of albinism (6.7 and 6.5%), and grey mould (1.3 and 1.2%) than those harvested from plants sprayed either with B alone or in control. Although, B alone could not influence the incidence of albinism and grey mould, but it reduced fruit malformation (3.4 and 3.1%) significantly. Further, Ca, B or their combination had not influenced the individual berry weight, but marketable fruit yield differed significantly. The lowest marketable fruit yield (149.3 g/plant) was recorded in plants under control, and the highest (179.2 g/plant) in plants sprayed with Ca + B. Similarly, such fruit were firmer; had lower TSS, higher acidity and ascorbic acid content at harvest than those in control. Similarly, such fruit after 5 days storage were firmer and brighter, and have significantly lower TSS (7.9 and 7.8%); higher ascorbic acid content (43.7 and 45.0 mg/100 g pulp) and acidity (1.08 and 1.07%) than those in control or those receiving B alone. Incidence of grey mould was significantly lesser in fruit, which received Ca (2.2%) or Ca + B (1.9%) than those, which received either B (8.1%) alone or those in control (8.4%). Our studies indicated that pre-harvest foliar application of Ca + B is quite useful for reducing the incidence of disorders and getting higher marketable yield in ‘Chandler’ strawberry.

Repartição de nutrientes nas flores, folhas e ramos da laranjeira cultivar Natal

As plantas cítricas produzem elevado número de flores, porém pequena porcentagem chega a fruto maduro. A fixação é influenciada por diversos fatores, com destaque para os nutricionais orgânicos e minerais. O objetivo do trabalho foi verificar a repartição de macro e micronutrientes nas flores, folhas e ramos de laranjeira e a contribuição nutricional das flores para os demais órgãos. Plantas de Citrus sinensis L., cultivar Natal sobre porta-enxerto de limoeiro cravo de 10 anos de idade, provenientes de pomar comercial, foram amostradas por ocasião do fluxo primaveril e separadas em flores, folhas e ramos. As flores representam dreno tanto para compostos orgânicos quanto para macro e micronutrientes. Sua massa seca na antese se iguala às das folhas e é maior que a dos ramos. A maior proporção de Ca, Mg e de Ni das três partes encontram-se nas flores de onde, possivelmente, passam em parte para o fruto em desenvolvimento. Sugere-se que aplicações foliares de cálcio, magnésio e níquel, em condições de deficiência, poderiam aumentar a produção através do seu efeito no florescimento.

The Effect of Calcium Sprays and Fruit Thinning on Bitter Pit Incidence and Calcium Content in ‘Honeycrisp’ Apple

ABSTRACT ‘Honeycrisp’ is a recently released cultivar of apple (Malus x domestica) developed by the University of Minnesota, now in high demand by growers and consumers. This cultivar is susceptible to bitter pit, especially when the trees are young and the fruit load is low. The effects of calcium (Ca) sprays, fruit thinning, vegetative growth, fruit and leaf nutrient concentration on bitter pit incidence, and two sampling methods for nutrient analysis were studied. Bitter pit incidence was associated with several variables, including Ca and phosphorus (P) concentrations in leaves and fruits, magnesium (Mg) concentration in leaves, and yield parameters. Fruit Ca concentration and content for the growing season were modeled, which allowed the determinations of Ca levels associated with bitter pit incidence. Our data suggest that plug analysis was less sensitive than fruit-segment analysis for finding differences in Ca concentrations.

Effect of in‐season calcium applications on cell wall physicochemical properties of nectarine fruit (Prunus persica var. nectarina Ait. Maxim) after harvest or cold storage

AbstractPre‐harvest calcium sprays with calcium chloride or with a commercial chelated calcium form at equivalent calcium rate were applied in nectarine trees at weekly intervals beginning 4 or 8 weeks before harvest, respectively. The fruits were harvested at commercial maturity stage and cold stored (0 °C, 95% RH) for 0, 2, 4 and 6 weeks, prior to their ripening at room temperature (20 °C) for 1 and 5 days. The interrelations between calcium content (total, cell wall and pectin‐bound), cell wall components (polyuronide, neutral sugar and cellulose content) and tissue firmness of the nectarine fruits were examined. The two strategies (four or eight calcium sprays) were equally effective at increasing the fruit calcium content. Calcium increased by 14–25% in the peel and by 8–11% in the flesh, whereas cell wall calcium increased by 7–17% in calcium‐sprayed compared to non‐sprayed fruits after harvest. Cell wall and pectin calcium increased with the increase of storage time both in sprayed and non‐sprayed fruits without a corresponding increase of total calcium and uronic acid content, indicating the formation of more sites for calcium binding as storage period increased. Neutral sugar and cellulose content remained unaffected by the application of calcium sprays. Copyright © 2006 Society of Chemical Industry

복숭아

복숭아 백도 품종에 칼슘의 효과를 평가하기 위해 <TEX>$CaCl_2$</TEX>을 포장에서 엽면시비 하였다. 엽면시비는 <TEX>$CaCl_2$</TEX> 단용 살포와 <TEX>$CaCl_2(Ca:\;400mg.kg^{-1})$</TEX> 과 보조제(amino acid: <TEX>$2g.kg^{-1}$</TEX>, phytic acid: <TEX>$2ml.kg^{-1}$</TEX> 및 wood vinegar: <TEX>$2g.kg^{-1}$</TEX>)를 혼용하여 6월 21부터 7월 4일까지 7일 간격으로 4번 살포하였다. 수확기에 잎과 과실에 Ca함량, 과실 강도, 당도, Monilinia fructicola에 의한 잿빛무늬병을 조사하였다. 저장 과실의 품질조사는 실온에서 14동안 저장 후 Ca 함량, 과실의 강도, 당도 및 자연부패 율을 조사하였다. 수확기 잎과 과실에 Ca 함량은 <TEX>$CaCl_2+amino$</TEX> acid 처리구에서 가장 높았으나(P=0.05), 과피에 Ca 함량은 처리구간에 유의차이가 없었다. 과실경도는 <TEX>$CaCl_2+amino$</TEX> acid 처리구에서 가장 높았다(P=0.05). 실온에서 14일 저장기간 중 자연부패(Rhizopus stolonifers)에 의한 부패 율은 <TEX>$CaCl_2+wood$</TEX> vinegar 처리구에서 가장 낮았다. 과실의 경도는 <TEX>$CaCl_2$</TEX>와 보조제를 혼용 처리한 구에서 높았다. 포장에서 잿빛무늬병의 발생 억제율과 잿빛무늬병원균(Monilinia fructicola)으로 인공 접종한 실내시험에서 발병 억제율을 조사한 결과 <TEX>$CaCl_2+phytic$</TEX> acid과 <TEX>$CaCl_2+amino$</TEX> acid 처리한 구에서 가장 효과가 높았다. 이들 결과는 과실의 칼슘함량 과 과실경도 증가, 병 발생 억제 및 자연부패 방지는 <TEX>$CaCl_2$</TEX>과 보조제를 혼용하여 엽면 살포할 경우 정의 상관관계가 있다는 것을 제시하고자 한다. To evaluate the effectiveness of the foliar spray of calcium on "Baekdo" peach fruit, we carried out experiments in the orchards. The sprays were applied with <TEX>$CaCl_2\;(Ca:\;400mg.kg^{-1})\;and\;CaCl_2$</TEX> with adjuvants (amino acid, <TEX>$2g.kg^{-1}$</TEX>; phytic acid, <TEX>$2ml.kg^{-1}$</TEX> and wood vinegar, <TEX>$2ml.kg^{-1}$</TEX>) for four times from June 12 through July 4 at weekly intervals. The fruits and leaves were evaluated for Ca content, firmness and incidence of Brown rot caused by Monilinia fructicola at harvest To evaluate fruit quality included Ca content, firmness natural decay during the storage, the fruits were stored at room temperature for 14 days. The Ca content in leaf and fruit flesh at harvest was significantly increased (P=0.05) in <TEX>$CaCl_2$</TEX> + amino acid treatment among <TEX>$CaCl_2$</TEX> treatments. However, there was not significant Ca content in fruit peel. The firmness of flesh increased significantly (P=0.05) in <TEX>$CaCl_2$</TEX> + amino acid treatment. The natural decay (Rhizopus stolonifers) during storage at the room temperature for 14 days, the fruit treated with <TEX>$CaCl_2$</TEX> + wood vinegar exhibited lowest (P=0.05) incidence. Also, the firmness of the fruit during storage was firmer with treated <TEX>$CaCl_2$</TEX> than untreated fruit. In the treatments of <TEX>$CaCl_2$</TEX> + phytic acid and <TEX>$CaCl_2$</TEX> + amino acid, it was possible to reduce incidence of Brown rot caused by M. fructicola most effectively in the field. In addition, inoculation with M. fructicola in fruits was also the most effective treatment for inhibiting disease development in vitro. These results suggested that the foliar spray of <TEX>$CaCl_2$</TEX> with adjuvants increased the content of Ca and firmness of the fruits positively. It also inhibited the natural decay and the Brown rot effectively.

Post-harvest disorders and mineral composition of apple fruits as affected by pre-harvest calcium treatments

The effect of pre-harvest calcium sprays, CaCl2 and Ca (NO3)2, on apple (Malus domestica) N, P, K, Ca and Mg content, storability and incidence of physiological disorders (superficial scald, bitter pit, physiological spot) was studied using two cultivars, ‘Krameri Tuviõun’ and ‘Talvenauding’. In the first year calcium treatment did not reduce any physiological disorders or loss of marketable yield. In the second year calcium treatment reduced storage losses until four months after storage. Bitter pit in ‘Krameri Tuviõun’ was unaffected by calcium treatment, but physiological spot of ‘Krameri Tuviõun’ and superficial scald of ‘Talvenauding’ were reduced by calcium treatment in the second year. Both physiological disorders of 'Krameri Tuviõun’ correlated negatively with Mg and P content and Mg/Ca ratio in apples. Superficial scald of ‘Talvenauding’ correlated negatively with Ca content and positively with K/Ca ratio, N/Ca ratio and Mg/Ca ratio in fruits. The conclusion can be made that content of Ca and its ratios with other nutrients plays an important role in the development of superficial scald on ‘Talvenauding’ fruits, and increasing Ca content in fruit can therefore be recommended for improving post-harvest quality of this cultivar. Since bitter pit in 'Krameri Tuviõun’ was not reduced by calcium treatment, it would be worth trying other measures for this cultivar.

Effects of pre-harvest foliar calcium sprays on fruit calcium levels and brown rot of peaches

Brown rot of stonefruits caused by Monilinia fructicola (Wint.) Honey continues to be responsible for significant crop losses in New Zealand despite the application of recommended fungicides. The goal of our research programme is to substantially improve brown rot management and in the first part of a multi-year programme, we investigated the hypothesis that supplementing a brown rot fungicide spray programme with calcium (Ca) reduces brown rot incidence. A range of commercially available Ca products were applied to peach ( Prunus domestica L.) trees (cv. ‘Scarlett O’Hara’) at two weekly intervals from 3–5 November until fruit harvest (January 2001 and 2002) in the Hawke's Bay region of New Zealand. Calcium content of the peach epidermis was significantly increased by at least 50% by Ca sprays, compared to unsprayed fruit in both seasons. Increasing the Ca content of fruit significantly reduced the incidence and severity of M. fructicola infections in fruit disk assays. Pre-harvest Ca applications also significantly reduced the number of brown rot infected fruit per tree at harvest and the incidence of postharvest rots. The integration of Ca foliar sprays into current brown rot management practices has been widely adopted by stone fruit growers in New Zealand as a practical tool to reduce brown rot losses.

Calcium Foliar Sprays for Control of Alfalfa Greening, Cork Spot, and Hard End in ‘Anjou’ Pears

ABSTRACT New calcium (Ca) spray materials were made available to test for their possible improvement over the often-used dry form of calcium chloride products. Four orchards of mature ‘Anjou’ pears (Pyrus communis L.) were selected for the experiments. Three Ca materials were used at equal Ca rates, consisting of a dry Ca material derived from calcium chloride (Mora-leaf-Ca) with and without Sylgard; a liquid Ca material derived from CaCl2 (Cal-Plex-12); and a dry Ca material derived from calcium oxide (Mira-Cal) at different concentrations. In one orchard, Mira-Cal Ca at the double rate had the lowest incidence of cork spot and hard end with the highest concentration of cortex Ca and acceptable fruit finish, closely followed by the standard rate of Mora-Leaf-Ca. In a second orchard, Mora-Leaf-Ca plus Sylgard 309 had the lowest incidence of cork spot and alfalfa greening. In the third orchard, Mora-Leaf-Ca had the lowest incidence of cork spot and the highest concentration of fruit Ca in peel and cortex. In the fourth orchard, Cal-Plex-12 Ca produced nearly complete control of cork spot and the highest concentration of fruit Ca in peel and cortex. When comparing commercial spray-machine application of 935 L ha−1, control of cork spot and fruit Ca absorption was improved with six calcium applications versus only two spray applications.

Foliar- and Fruit-applied Strontium as a Tracer for Calcium Transport in Apple Trees

Application of calcium (Ca) sprays is a recommended practice to reduce the incidence of Ca-related disorders such as bitter pit in apple (Malus ×domestica), but effectiveness of sprays to increase Ca concentrations in the fruit is not always consistent. Strontium (Sr) has been used as a Ca analog to evaluate Ca transport processes and distribution in plants. A field study was conducted using foliar- and fruit-applied Sr as a tracer for Ca transport in 20-year-old `Honeycrisp' apple trees on Malling.26 (M.26) rootstock. The objectives of this study were to 1) measure the amount of Sr translocation from leaves to fruit, 2) determine the effectiveness of eight sprays applied over the growing season vs. four late-season sprays on increasing Sr concentrations in leaves and fruit, and 3) evaluate the effect of an experimental adjuvant consisting of alkyl-polysaccharides and monosaccharides on spray efficacy. Seven treatments were tested, which included a control and six Sr treatments applied in various combinations with or without an adjuvant. Trees were sprayed four or eight times during the growing season, either directly to leaves and fruit or to leaves only (fruit covered during application). Spray treatments did not significantly affect total fruit fresh or dry weight. Although some discrimination between Ca and Sr was detected, the similar distribution of Ca and Sr in fruit tissue of control treatments suggested that Sr is a suitable tracer for Ca. Based on the covered vs. uncovered fruit treatments, about 11% to 17% of the Sr in the fruit came from Sr applied directly to the leaves. Eight spray applications over the growing season more than doubled both the concentration and content of fruit Sr compared with four late season sprays. The tested adjuvant doubled Sr absorption by and translocation to fruit compared with not using an adjuvant. Assuming similar transport for Ca and Sr, and adjusting for the atomic weight of Ca relative to Sr, the maximum increase in fruit Ca concentration at harvest from foliar and fruit applications (eight sprays with adjuvant and uncovered fruit) would have been as follows: core = 78 mg·kg–1; flesh = 35 mg·kg–1; peel = 195 mg·kg–1; entire fruit = 67 mg·kg–1. In addition to being an underused tool for studying Ca transport patterns, the results also suggest that use of Sr may be a novel technique for testing the efficacy of various adjuvants used to enhance uptake and transport of Ca in leaves and fruit.

INFLUENCE OF DIFFERENT SUBSTRATES AND NUTRIENT SOLUTIONS ON THE YIELDS AND THE INCIDENCE OF ABIOTIC DISORDERS OF BROCCOLI

INFLUENCE OF DIFFERENT SUBSTRATES AND NUTRIENT SOLUTIONS ON THE YIELDS AND THE INCIDENCE OF ABIOTIC DISORDERS OF BROCCOLI

The effect of preharvest calcium sprays on quality attributes, physicochemical aspects of cell wall components and susceptibility to brown rot of peach fruits ( Prunus persica L. cv. Andross)

This study was planned to evaluate the effect of preharvest calcium sprays on physicochemical aspects of cell wall components, activity patterns of pectin-modifying enzymes and susceptibility to brown rot ( Monilinia fructicola) of peach fruits ( Prunus persica L. cv. ‘Andross’). Six or 10 preharvest calcium sprays were applied with two different formulas (calcium chloride and an ethylenediamine tetraacetic acid (EDTA) chelated calcium form) in equimolar calcium concentration (0.12% Ca, w/v). After harvest, peach fruits were cold stored (0 °C, 95% R.H.) up to 4 weeks. Calcium content increased significantly in the calcium-sprayed peaches both in the peel (25–42%) and in the flesh (11–17%), 1 d after harvest. Calcium chloride sprays were more effective than those of chelated calcium, whereas the increase of calcium content in the fruits seems to be unaffected by the 6 or 10 calcium sprays. The increase of cell wall calcium corresponded to increase of calcium in the insoluble pectin fraction, whereas no differences were detected in the calcium of water-soluble pectin fraction. Ethylene production, respiration rate, uronic acid content and activity of pectin-modifying enzymes did not indicate substantial differentiations by preharvest calcium sprays as ripening progressed after harvest or cold storage. Calcium sprays resulted in significant decrease of brown rot development, although no effect on disease incidence was recorded.