Vegetative and Reproductive Responses of Apple Trees to Zinc Fertilization under Conditions of Acid Coarse-Textured Soil

ABSTRACT

The aim of this study was to examine response of apple (Malus domestica Borkh.) trees to zinc (Zn) fertilization under conditions of acid coarse-textured soil with low 1M hydrochloric acid (HCl)-soluble Zn level. The experiment was carried out during 2004-2005 at a commercial orchard in Central Poland on mature ‘Jonagold’ apple trees/M.26 EMLA, planted at a spacing of 4 × 2.5 m. The trees were sprayed with Zn: (i) prebloom, at the stage of silver tip, and tight cluster at a rate of 140 and 100 g ha^{? 1}, respectively, (ii) postbloom, at the stage of petal fall, and 2 weeks later at a rate of 80 g ha^{? 1} in each spray treatment, and (iii) postharvest, 4–5 weeks before the natural leaf fall at a rate of 500 g ha^{? 1}. Other trees were supplied with Zn to soil at a rate of 3 kg ha^{? 1}. In all the studied treatments, Zn was used as ethylenediaminetetraacetic acid (EDTA). Trees unsupplied with Zn served as the control. Tree vigor, fruit set, yield and fruit quality at harvest (mean fruit weight, firmness, color, russeting, soluble solids concentration, and acidity) were not influenced by Zn fertilization. Postharvest Zn sprays slightly damaged leaf tissues but did not cause defoliation. Soil Zn application raised Zn concentrations in flowers, and leaves 28, 56, and 84 days after petal fall. Pre- and postbloom Zn sprays increased Zn status in flowers and leaves 28 days after flowering, respectively. The obtained results indicate that Zn fertilization of ‘Jonagold’ apple trees with Zn status in mid-summer leaves and flowers of 17 mg kg^{? 1} and 27 mg kg^{? 1}, respectively, is not successful in improving vigor and tree yield.     

Effect of Postharvest Sprays of Boron and Urea on Yield and Fruit Quality of Apple Trees

ABSTRACT

The objective of the experiment was to examine the effect of postharvest sprays of boron (B) and urea on apple tree yield and fruit quality. The study was conducted during 2002–2003 at a commercial orchard in central Poland on mature ‘Jonagold’ apple trees/M.26 planted on a sandy loam soil with low B status. All experimental trees received soil-applied nitrogen (N) at a rate of 50 kg ha^?1 at bud break. The following spray treatments were performed: (1) postharvest B spray three to four weeks before leaf abscission at a rate of 1.2 kg ha^?1; (2) postharvest urea-N spray at the same time as B spraying at a rate of 18.4 kg ha^?1; and (3) combined B spray with urea at the same time and at the same rates as in the combination of treatments (1) and (2). Trees not sprayed with B and urea served as a control. The results showed that all spray treatments damaged leaves, but only postharvest urea spray and combined B spray with urea caused defoliation. Postharvest B spray with/without urea improved flower B status, fruit set, and tree yield. However, the efficiency of combined B spray with urea in improving reproductive growth was lower than that of foliar B application without the addition of urea. Postharvest sprays of B and urea had no effect o n blushing, flesh firmness, or soluble solids concentration of apple fruit. These results indicated that under B-deficiency conditions, postharvest B sprays are successful in improving reproductive growth and should be recommended without the addition of urea. It is suggested that combined B sprays with urea may be applied in the autumn to apple trees with limited soil B and N availability.     

RESPONSE OF ‘GRANNY SMITH’ APPLE TREES TO FOLIAR TITANIUM SPRAYS UNDER CONDITIONS OF LOW SOIL AVAILABILITY OF IRON,MANGANESE, AND ZINC

The aim of the study was to examine impact of foliar titanium (Ti) sprays on vegetative and reproductive response of apple (Malus domestica Borkh.) trees under conditions of low soil availability of iron (Fe), manganese (Mn), and zinc (Zn). The experiment was conducted during 2005–2006 at a Experimental Station in Isparta region, Turkey, on mature ‘Granny Smith’ apple trees/M.9, planted at a spacing of 3.5 × 1.5 m, on fine-textured soil with neutral reaction, medium status of organic matter, high amounts of available phosphorus (P), potassium (K), and magnesium (Mg), and low availability of Fe, Mn, and Zn. The trees were sprayed with Ti-ascorbate at the green and pink bud stage, petal fall, and 3, 6, and 9 weeks after full bloom, at a rate of 3 g Ti ha^?1 per spray. The efficiency of Ti sprays was compared to combined sprays of Fe, Mn, and Zn [chelated with ethylenediaminetetraacetic acid (EDTA)], applied at the same terms as Ti sprays, at rate of 36 g, 36 g and 24 g per spray, respectively. Trees unsprayed with Ti, Fe, Mn, and Zn served as the control. It was shown that summer leaf Ti concentrations of the trees untreated with Ti were high, varying from 34 to 36 mg kg^?1 dry matter. Foliar Ti sprays increased leaf status of this nutrient but they had no effect on nutrition of essential macro- and microelements, tree vigor, and fruit yield. Mean apple weight, coloring, firmness, soluble solids concentration, and titratable acidity of fruit were not also influenced by Ti sprays. Foliar sprays of Fe, Mn, and Zn improved leaf status of nitrogen (N), Mg, Fe, Mn, and Zn; leaves of the trees sprayed with those micronutrients were also greener, and contained more Fe²⁺ than those of the control plants. Combined sprays of Fe, Mn, and Zn improved tree vigor and fruit yield.     

‘Schattenmorelle’ Tart Cherry Response to Boron Fertilization

ABSTRACT

The objective of the experiment was to examine the effects of soil and foliar applications of boron (B) on tart cherry (Prunus cerasus L.) tree vigor, yield, and fruit quality. The study was conducted during 2003–2004 on mature ‘Schattenmorelle’ tart cherry trees grown at a commercial orchard in central Poland on coarse-textured soil with low B content. Trees were supplied with B as foliar sprays or via soil application. Foliar B sprays were performed: (1) in the spring, at the white bud stage, when 5%–10% of flowers were at full bloom, and 5 d after petal fall, at a rate of 0.2 kg B ha^?1 per each spray treatment; and (2) in the fall, approximately six weeks before the natural leaf fall, at a rate of 0.8 kg B ha^?1. Soil B application was made at the bud-break stage at a rate of 2 kg ha^?1. Trees untreated with B served as a control. Spring and fall B sprays increased flower B concentrations, but had no effect on summer leaf B status. Leaf B concentrations of trees with B supplied to the soil were higher than those of the control trees. However, soil B application had no influence on flower B level. Vigor and yield of tart cherry trees were not influenced by B fertilization. Also, mean fruit weight and titratable acidity of fruit did not differ among treatments. Fruit of trees with B supplied to the soil had higher soluble solids concentration (SSC) than those of the control plants. In conclusion, high yield of tart cherry can be obtained on soils with water-soluble B concentrations as low as 0.32 mg kg^?1. It is also postulated that at low soil-B availability, under conditions of low-light intensity during fruit ripening, soil-B application increases SSC in tart cherry fruit.     

“Szampion” Apple Tree Response to Foliar Titanium Application

Abstract

The aim of the study was to examine effect of foliar titanium (Ti) application on vigor, fruiting, and quality and fruit storability of apple (Malus domestica Borkh.) trees. The experiment was carried out during 2000–2001 on mature “Szampion” apple trees/M.26 planted in a course-textured soil with a low level of organic matter and optimal status of nutrients. The trees were sprayed with TiCl₄ solution: (1) before blooming, at the stage of green and pink bud; (2) during blooming, at the beginning of flowering and the petal fall; (3) after blooming, 1 and 3 weeks after petal fall; and (4) before fruit picking, 4 and 2 weeks before commercial harvest. In each spray, Ti was applied at a rate of 2.5 g ha^?1. Trees sprayed with water served as a control. The results showed that foliar Ti sprays had no effect on vigor, fruit set, yielding, and appearance and apple storability. Foliar Ti application after flowering increased leaf Ti 30, 60, and 90 days after full bloom. Titanium sprays before harvest enhanced status of this element in fruit and leaves 90 days after bloom. Concentrations of essential macro- and microelements in leaf and fruit tissues were not affected by foliar Ti sprays. These results indicate that foliar Ti sprays of apple trees are not beneficial under conditions of optimal nutrition.     

Response of ‘Jonagold’ Apple Trees in the First Three Years after Planting to Mono-Ammonium Phosphate Fertilization Under Replant Problem Conditions

Abstract

The objective of the experiment was to examine response of immature apple trees to application of mono-ammonium phosphate (MAP) fertilizer on replant problem soil. The study was carried out during 2001–2003 under a greenhouse on ‘Jonagold’ apple trees/M.9 EMLA planted singly in 50 L polyethylene containers filled with a sandy loam soil with low status of both organic matter and phosphorus (P) in soil solution. This soil originated from an apple orchard unfertilized with P for 23 years. The biological test showed the presence of specific replant disease in the soil. Immediately before apple tree planting, the soil was mixed with MAP at rates of 1, 2, and 3 g L^{? 1}. Trees grown in the soil untreated with MAP served as a control. Each year apple trees were drip-irrigated and supplied with nitrogen (N) at differentiated rates to achieve a level of 50 g N per plant. The results showed that MAP application increased soil solution P status. Simultaneously, MAP supply at rates of 2 and 3 g L^{? 1} caused a drop in soil pH value in the last two years of the experiment. MAP treatments increased both dry weight and length of fine roots (< 2 mm in diameter), vigor of trees, the number of flower clusters per tree, flower intensity, the number of fruits per tree, and P concentrations in leaf and fruit tissues. Fruits from MAP-supplied trees were firmer than those of the control trees. Mean fruit weight, titratable acidity, and soluble solids concentration of ‘Jonagold’ apples at harvest were not influenced by MAP treatment. Fruits from MAP-supplied apple trees had increased calcium concentration only in one year. It is concluded that pre-plant application of MAP at a rate of 1g L^{? 1}can be recommended on coarse-textured soils with low P status in soil solution to increase precocity of apple trees. However, MAP-supplied apple trees have to be watered to avoid the risk of osmotic stress.     

Alternative procedure for total phosphorus determination in plant tissue

Abstract

Surface liming will prevent the formation of an ‘acid roof’ on the surface of soil cropped in no‐till corn (Zea mays L.). A study was begun in 1985 to determine the effectiveness of unincorporated liming in raising pH in no‐till soil which had developed significant acidity throughout the upper 15 cm. Lime was applied at 0, 3.36, 6.72 and 10.08 Mg ha^‐1. All lime was applied on 26 April 1985 and was not incorporated. The pre‐liming pH at 0‐5 cm below the surface was 4.5; after two months the pH was raised to 5.6, 5.8, and 6.0 by 3.36, 6.72 and 10.08 Mg ha^‐1 of lime, respectively. After 19 months soil‐pH was raised to 6.0, 6.4 and 6.6 by liming at 3.36, 6.72 and 10.08 Mg ha^‐1 respectively. Soil‐pH below 5 cm was not affected by any rate of lime during the first 19 months after liming. Tissue analysis of corn ear leaves indicated that calcium uptake was increased significantly by lime in 1985, while manganese uptake was significantly reduced. In 1986, increases in calcium were greater than in 1985 and addtional significant reduction in manganese uptake was accompanied by significantly reduced zinc and copper uptake. In both 1985 and 1986, a trend toward lower average corn grain yield in unlimed plots than in limed plots was noted, but the yield increases due to lime were not statistically significant in either year. This study will be continued as a long term investigation of lime penetration into no‐till soil and response of corn to soil‐pH changes.     

Effects of preharvest calcium sprays on apple and pear quality

Fruit from apple (Malus domestica Borkh.) and pear (Pyrus communis L.) trees sprayed with calcium chloride (CaCl₂) had higher fruit calcium (Ca) concentrations by 10% or more than the unsprayed control trees. In ‘Delicious’ and ‘Golden Delicious’ apples, the incidences of bitter pit, scald, and internal breakdown were substantially reduced with CaCl₂ sprays. In most instances, firmness, total acidity, and juiciness ratings of apples were improved with CaCl₂ sprays. In ‘Anjou’ pears, the incidence of cork spot was reduced with CaCl₂ sprays. Only sprays of NutriCal and CaCl₂ + Regulaid showed substantial increases in fruit firmness of ‘Anjou’ pear. In 1991, yield of ‘Anjou’ pear trees was increased by 36% with CaCl₂ sprays compared with the control trees.     

BORON UPTAKE AND DISTRIBUTION IN FIELD GROWN CITRUS TREES

In low fertility tropical soils, boron (B) deficiency impairs fruit production. However, little information is available on the efficiency of nutrient application and use by trees. Therefore, this work verified the effects of soil and foliar applications of boron in a commercial citrus orchard. An experiment was conducted with fertigated 4-year-old ‘Valencia’ sweet orange trees on ‘Swingle’ citrumelo rootstock. Boron (isotopically-enriched ¹⁰B) was supplied to trees once or twice in the growing season, either dripped in the soil or sprayed on the leaves. Trees were sampled at different periods and separated into different parts for total B contents and ¹⁰B/¹¹B isotope ratios analyses. Soil B applied via fertigation was more efficient than foliar application for the organs grown after the B fertilization. Recovery of labeled B by fruits was 21% for fertigation and 7% for foliar application. Residual effects of nutrient application in the grove were observed in the year after labeled fertilizer application, which greater proportions derived from the soil supply.     

Structure liming enhances aggregate stability and gives varying crop responses on clayey soils

It has been suggested that liming can improve soil structure and thereby decrease losses of particles and associated nutrients. In this study, two types of structure lime, slaked lime (Ca(OH)₂) and a mixed product of calcium carbonate (CaCO₃) and slaked lime (Ca(OH)₂), were applied at three different rates in field trials on clayey soils (23%–40% clay). A combination of primary tillage and structure liming was also studied, in a split-plot trial on a clayey soil (25% clay). Aggregate (2–5?mm) stability, measured as reduction in turbidity (which is strongly correlated with losses of particulate phosphorus), was significantly increased with the highest application rates of both structure lime products. Aggregate size distribution was also improved with structure lime, creating a finer tilth in the seedbed. Yield response to structure lime was not consistent, with both negative and positive responses over the four-year study period. Positive yield responses can possibly be attributed to the finer tilth preventing evaporation in two dry growing seasons. Negative yield responses were probably an effect of impaired phosphorus availability associated with limited precipitation in May-July in 2011 and 2013. Two years after liming, soil pH levels were significantly elevated in plots with the highest application rate of structure lime, whereas no significant increases were found three years after liming. However, a lingering effect of liming was still detectable, as manganese concentration in barley grain was significantly lower in plots with the highest application rates of both structure lime products in the fourth study year. These results indicate that structure liming can be used as a measure to mitigate phosphorus losses from clayey soils, thereby preventing eutrophication of nearby waters. However, the yield response was varying and unpredictable and thus further investigations are needed to determine the circumstances in which field liming can act efficiently not only to prevent phosphorus losses, but also to ensure consistent yield increases.     

BORON APPLICATION ON A CHESTNUT ORCHARD: EFFECT ON YIELD AND QUALITY OF NUTS

Although boron (B) deficiency in chestnuts (Castanea sativa Mill.) has been identified in Portugal and B fertilization was carried out in some orchards, the post-treatment evaluations have not been made to date. So the objective of this trial was to confirm the B deficiency and to quantify the effect of B applications to the soil on nut yield and quality. In October 2006, a fertilizer trial was established in a 15 year-old orchard in a very acid soil derived from siliceous schists. Soil liming and a basal fertilization were carried out in 16 trees and two levels of sodium tetraborate (Granubor, 14.6% B) were applied to eight trees: control (B0) and 100 g of Granubor per tree (B1). In the beginning of September chestnut leaves were collected from five trees and analyzed for macro- and micronutrients. Nut productivity was measured per tree and some nut quality parameters were evaluated, including the chemical composition of the kernel (soluble sugars, starch, total fiber, crude protein, and crude fat) in 2007, and dry matter, nut caliber, and fruit damage in 2007 and 2008. Boron fertilization of chestnuts significantly increased nut production: 75% in the first year (8 kg and 14 kg per tree, respectively, in the B0 and B1) and, in the second year, was over four times higher (4 kg and 17 kg per tree, respectively, in the B0 and B1). No significant differences were found in dry matter, nut caliber, nut damage and chemical composition of the kernel in the first year, but in the second year lower fruit damage by chestnut tortrix (P<0.0089) was observed. Foliar analyses exhibit relatively low B concentrations in the control trees (average value of 8 mg kg^?1) in both years, while in the fertilized trees the foliar B concentration were in average 61 mg kg^?1 in the first year, and 34 mg kg^?1 in the second year. The large drop in the foliar B concentration in the second year suggests the need to monitoring the nutrient status of chestnut orchards or more frequent of B application than usual practice.     

“JONAGOLD” APPLE FRUIT QUALITY AS INFLUENCED BY FALL SPRAYS WITH CALCIUM CHLORIDE AT HIGH RATES

The aim of the experiment was to examine the effects of fall sprays with calcium (Ca) as calcium chloride at high rates on ‘Jonagold’ apple (Malus domestica Borkh.) fruit quality. Trees were sprayed with Ca both in summer (9, 7, 5, and 3 weeks before fruit harvest) at a rate of 3 kg Ca ha^?1and in fall (one week before fruit harvest) at rates of 8, 16, or 24 kg Ca ha^?1. Fall Ca sprays resulted in leaf injuries and defoliation; however they had no effect on cold hardiness of one-year-old shoots. Fruit yield, weight, maturity at harvest, surface condition, and color were not influenced by Ca sprays during three consecutive years. Fruit Ca concentration corresponded with amount of Ca applied. In two of three years, summer Ca sprays decreased sensitivity of apples to bitter pit. Fruit sprayed with Ca both in summer and in fall had higher firmness and titratable acidity after storage and were more resistant to bitter pit and internal breakdown than controls and fruit sprayed only with Ca in summer. Apples sprayed with Ca in summer and in fall at the highest rate were the least sensitive to bitter pit and internal breakdown and were more resistant to decay than control fruit.     

Effects of long-term contrasting lime and phosphorus applications on barley grain yield,root growth and abundance of mycorrhiza

Lime and phosphorus (P) applications are common agricultural management practices. Our aim was to quantify the effects of long-term application practices on root growth and abundance of arbuscular mycorrhizal fungi (AMF) under field conditions. We assessed the effects of lime and P fertilizer applications on barley yield, root growth and AMF abundance in 2016. Treatments were no, low, medium and high liming rate corresponding to application of 0, 4, 8 and 12 Mg lime ha⁻¹ every 5–9 years since 1942 combined with no or yearly application of 15.6 kg P ha⁻¹ since 1944. At harvest, grain yield, root intensity (core-break) and AMF abundance at different soil depths were estimated. Root development was monitored during early growth with minirhizotrons in treatments receiving low, medium and high liming rates and P fertilization. A quadratic model relating grain yield to liming rate estimated yields to peak at 6.4 Mg lime ha⁻¹ with yields of 4.2 and 3.2 Mg grain ha⁻¹ with and without P fertilization, respectively. Low and medium liming rates resulted in greater AMF abundance, especially in the no P treatments. During early growth in P-fertilized treatments, 77% and 65% more roots developed in the soil profile when treated with medium and high liming rate, respectively, compared to low liming rate. We conclude that long-term application of lime in soils receiving yearly P fertilization improved conditions for root growth in soil layers below 30 cm, but at the high liming rate, this did not translate into higher yield.     

Response of Primocane-Fruiting ‘Polana’ Red Raspberry to Boron Fertilization

The objective of this study was to examine the response of red raspberry to boron (B) fertilization. The experiment was carried out during 2002–2003 in a commercial plantation in central Poland on primocane-fruiting ‘Polana’ raspberries planted on a sandy loam soil with low status of organic matter and hot water-extractable B. Raspberries were fertilized with B via foliar or soil application. Foliar B sprays were made four times per season: two weeks before flowering, at the beginning of blooming, and three and six weeks later. In each spray treatment, B was used at a rate of 0.1 kg ha^?1. Soil B was applied at the stage of bud break at a rate of 1 kg ha^?1. Plants untreated with B served as a control. The results showed that B fertilization, regardless of application mode, increased flower and leaf B concentrations, fruit set, and berry yield. Fruit of B-fertilized plants were firmer, and had higher soluble solids concentrations and numbers of drupelets than those of the control plants. Boron fertilization had no effect on plant vigor, mean berry weight, and titratable acidity of fruit. The obtained results indicated that on coarse-textured soils with low B status, soil or foliar B application should be recommended in red raspberry cultivation to increase yield and improve berry quality.     

Midsummer copper sprays have no effect on ‘delicious’ apple fruit color grade or typiness

Recent reports suggested that multiple midsummer copper (Cu) sprays could improve the proportion of apple fruit (Malus × domestica Borkh.) being packed in the reddest market color grades. We conducted a three‐year field experiment in a low‐Cu orchard with a history of poor fruit coloring. We applied multiple mid‐summer sprays of Cu sulfate and basic Cu sulfate in 1994 and 1995 to ‘Bisbee Delicious’ and ‘Oregon Spur II Delicious’ apple trees. Plant tissue nutrient levels, fruit color grade, and fruit typiness were evaluated in the years of application and the following year. The Cu sprays increased leaf Cu in the years of application; however, leaf Cu in the Cu‐sprayed plots returned to or very near to background concentrations in the year after sprays were terminated. The Cu treatments did not increase the proportion of fruit in the reddest market color grades or influence five fruit typiness indices of either apple cultivar. Although midsummer Cu sprays may not enhance apple fruit red color or typiness, they may be useful for increasing overall tree Cu status, particularly for long‐season cultivars which are harvested too late for postharvest sprays to be effective.     

Iron and/or acid foliar spray versus soil application of Fe-EDDHA for prevention of iron deficiency in Valencia orange grown on a calcareous soil

A two-year experiment was conducted in an iron(Fe)-deficient orchard with calcareous soil to find out an alternate method for soil application of Fe ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) in orange trees. Foliar sprays of Fe-EDDHA (5 g l^?1, pH = 7.8), sulfuric acid (pH = 3), citric acid (5 g l^?1, pH = 2.4), Fe (II) sulfate solutions (250, 500, and 750 mg Fe l^?1) with their initial pH (6.5, 6.35, and 6.12) and reduced ones to pH of 3 were compared with soil applied (75 g tree^?1) Fe-EDDHA and a control test. Although optimum chlorophyll content, leaf Fe concentration, fruit quantitative and qualitative attributes were resulted from soil application of Fe-EDDHA, repeated sprays of Fe-EDDHA or acidified Fe solutions created suitable results. Acidification of Fe solutions made them more effective in alleviation of leaf Fe concentration and Fe chlorosis, probably due to remobilization of inactive Fe within the plant and prevention of Fe oxidation and precipitation in foliar solutions.     

Tomato response to long‐term potassium and lime application on a sandy ultisol high in non‐exchangeable potassium

In a ten‐year study of potassium (K) and lime application to a Kalmia sandy loam (fine‐loamy, siliceous, thermic Typic Hapludult), a soil high in nonexchangeable K, corn (Zea mays L.) and soybean [Glycine max (L.) Herr.] have not responded to applied K. The objectives of this study were to determine if a high K‐requiring crop such as tomato (Lycocersicon esculentum Mill. cv. Redpak) would respond to KCl fertilizer rate or lime type (dolomitic, calcitic, and mixed) and rate on such a soil. Potassium was applied at 0, 56, and 112 kg K/ha every year for ten years. Lime was applied at 0, 2, and 9 Mg/ha in calcitic, mixed, and dolomitic forms twice in ten years (1970 and 1973). In 1980, the tenth year of the study, tomato fruit was harvested by hand once‐over to simulate machine harvest and divided into four maturity groups by color. Soil pH was higher with dolomitic than calcitic lime. Soil K saturation was not influenced by lime rate or type. Fruit yield and leaf phosphorus (P), calcium (Ca), and magnesium (Mg) concentrations increased with increasing lime rates. Leaf K, manganese (Mn), iron (Fe), boron (B), copper (Cu), zinc (Zn), barium (Ba), strontium (Sr), and aluminum (Al) concentrations decreased with increasing lime rate. Leaf Mn, Ba, and Sr concentrations were lower with dolomitic than with calcitic lime. Lime type had no effect on tomato yield. Wide ranges in basic cation saturation ratios had little effect on yield. Soil K saturation and leaf K, Zn, and Ba concentrations increased with increasing K rate. Soil Ca and leaf Ca, Mg, and Al concentrations decreased with increasing K rate. Applied K had no effect on total yield but onceover marketable yield increased linearly with increasing K rate. Marketable yield increased 14% with an increase in K rate from 0 to 56 kg/ha. Thus, fruit maturity was apparently hastened by K fertilization.     

Improvement of “Kinnow” mandarin fruit productivity and quality by urea,boron and zinc foliar spray

The present study was carried out on Kinnow mandarin trees (Citrus reticulata Blanco) to study the effect of urea, zinc (Zn) and boron (B) foliar sprays either alone or in combinations on fruit yield and quality. Trees were grown in alkaline sandy loam soil at Dirab, Riyadh, Saudi Arabia. All trees were sprayed twice: before full bloom (February) and after fruit set (April) during two growing seasons. The obtained results showed a significant increase in tree yield and enhancement in fruit physical characteristics (fruit weight, pulp, juice, volume, length and diameter), as well as fruit chemical characteristics [soluble solids content, acidity, pH, total sugars and ascorbic acid] by all foliar treatments in comparison with the control (water only) in both seasons. Spraying urea in combinations with B and Zn resulted in higher fruit yield and better physico-chemical characteristics as compared with urea only, urea + B or urea + Zn.     

EFFECT OF AUTUMN CALCIUM SPRAY AT A HIGH RATE ON ‘GRANNY SMITH’ APPLE QUALITY AND STORABILITY

The aim of the study was to examine effect of autumn calcium (Ca) spray at a high rate on apple quality and storability. The investigation was carried out during 2005–2006 in Isparta district, Turkey, under semi-arid conditions, on mature ‘Granny Smith’ apple trees/M.9 EMLA, planted at a spacing of 3.5 × 1.5 m on fine-textured soil rich in Ca. The trees were sprayed with Ca in summer and/or in autumn, using organically complexed Ca to avoid possible leaf and fruit injuries. In autumn (10 days before harvest), the trees were sprayed with Ca at a rate of 8 kg ha^?1. In summer, the another trees were sprayed with Ca six times at a rate of 1.5 kg ha^?1 in each measure; the first spray treatment was performed 6 weeks after full bloom, and the others at 7–9 day intervals. The third part of the trees was sprayed with Ca in summer as well as in autumn, at the same terms and rates as given above. Trees unsprayed with Ca served as the control. It was found that Ca sprays in autumn or in summer plus in autumn damaged leaves; however those treatments did not caused defoliation. Calcium sprays had no effect on apple yield, mean fruit weight, fruit skin russeting, and firmness, soluble solids concentration and titratable acidity of fruit at harvest. Fruit flesh Ca concentrations of the control trees were high. However, the highest fruit Ca concentration was recorded on the trees sprayed with Ca in summer plus in autumn. Calcium sprays in summer or in autumn increased fruit Ca concentrations but their effects were weaker than summer plus autumn Ca applications. After 100 days of refrigerated air storage, soluble solids concentration of fruit did not differ between the studied combinations. Only apples sprayed with Ca in summer plus in autumn were firmer and contained more organic acids than the control fruit. During storage, there were neither pathogenic diseases nor physiological disorders. Based on the obtained results we conclude that Ca sprays in summer plus in autumn at high rate can prolong ‘Granny Smith’ apple storage even thought initial fruit Ca concentration is as high as 502–504 mg Ca kg^?1 DW or 84.1–84.8 mg Ca kg^?1 FW.     

Iodine uptake and translocation in apple trees grown under protected cultivation

Background and Aims : Agronomic biofortification of food crops with iodine may improve the dietary intake of this trace element, which is essential for human development and health. So far, little is known about the suitability of this technique in pome fruits. The objectives of this study were (1) to investigate uptake and translocation of exogenously applied iodine in apple trees, (2) to identify possible strategies of iodine biofortification for this type of fruit, and (3) to evaluate interactions between foliar applied iodine and selenium. Methods : Apple trees were cultivated in a plastic tunnel for two growing seasons. Iodine was applied via leaves or substrate. During the 2^nd year, simultaneous foliar application of iodine and selenium were tested as well. At harvest time, iodine and selenium content in leaves and fruits were determined. The phytoavailable iodine concentration in the growing medium was analyzed following an extraction with calcium chloride. In addition, the dynamics of iodine applied as potassium iodide and iodate in a peat‐based substrate was investigated in an incubation experiment without plants. Results : The iodine concentration in washed apples increased more than 100‐fold, valuing around 50 µg (100 g FM)^?1 by foliar application of iodine as compared to the control treatment. However, this level was only achieved in fruits which were directly wetted by the spray solution. The translocation of leaf‐absorbed iodine to fruits was negligible. Following a substrate fertilization, the fruit iodine content remained rather low due to a strong retention of iodine in the growing medium. When using foliar sprays, the addition of selenium did not affect the iodine enrichment of the apple fruits. Conclusions : Foliar fertilization of iodine seems to be a promising method to biofortify apples with iodine. The level of I achieved in apple fruits by means of foliar fertilization can significantly contribute to the daily I intake requirement of humans.