Fruit nutrient accumulation of four orange varieties during fruit development 1

Evaluation of nutrient accumulation trends in fruit during fruit development and nutrient status in the leaves are important components defining nutrient requirements. Such nutrient demand should be met by nutrient supply in order to develop optimal rate and timing of fertilizer application. In a 3‐year study the citrus (orange) varieties, ‘Valencia’, ‘Parson Brown’, ‘Hamlin’, and ‘Sunburst’ were fertilized with either 168, 224, or 280 kg N ha^‐1 yr^‐1 as a broadcast application of N:P:K dry soluble granular fertilizer. These rates did not significantly affect the fruit nutrient status, juice quality, or nutrients concentrations in the spring flush. The concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the fruit decreased with their enlargement during June through November. However, micronutrient concentrations in the fruits increased from June through August or September and then decreased. Fruit dry weight was greatest in ‘Valencia’ followed by ‘Hamlin’, ‘Parson Brown’, and ‘Sunburst’ varieties. Soluble solids concentration (SSC) were higher in ‘Valencia’ and ‘Sunburst’ fruit than in the other two varieties. Other juice quality parameters were not significantly different among the varieties. This study indicated non‐significant influence of fertilizer rates on concentrations of various mineral elements in 6‐month‐old spring flush with most of those concentrations within the optimal ranges.     

Effect of saline irrigation on the biomass yield,and the protein,nitrogen, phosphorus,and potassium composition of alfalfa in a pot experiment

During 1994–1995, field experiments were conducted in six apple orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Lobo’, ‘Aroma’, and ‘Åkero’. Fruit samples were picked at about one week before commercial maturity and stored for three to six months at 2 to 4°C and 85–95% relative humidity. During storage the percentage of physiological disorders was visually recorded. Fruit nitrogen (N) and calcium (Ca), firmness, diameter, juice titratable acidity (TA), and soluble solids concentrations (SSC) were determined at harvest. Nitrogen and Ca in the soil and leaves collected during fruit development were determined. The ranges in fruit N were 296–624 and Ca 27–68 mg kg^‐1 fresh weight, and in the leaves N 15–23 and Ca 9–19 g kg^‐1 dry matter. The N/Ca ratio was 5 and 16 and 0.9 and 2.3 in fruit and leaves, respectively. There was more variation between years in N and Ca contents of leaves than that of fruit. Other fruit quality characteristics varied between seasons and cultivars. Leaf N correlated positively with fruit diameter and negatively with fruit dry matter. The incidence of physiological disorders on apples after three month storage was 2 to 13% and after six months 10 to 95%. Fruit with Ca content below 45 mg kg^‐1 fresh weight were susceptible to bitter pit ('Aroma’ and ‘Åkero') and Jonathan spot ('Red Atlas'). The cultivar ‘Melba’ was susceptible to bruising damages and ‘Raike’ and ‘Red Atlas’ were affected more with internal breakdown and core browning.     

FOLIAR APPLICATION OF BORON INFLUENCES THE LEAF MINERAL STATUS,VEGETATIVE AND REPRODUCTIVE GROWTH,YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN (CITRUS RETICULATA BLANCO.)

The effects of foliar application of boron (B) in the form of boric acid on vegetative and reproductive growth, yield and fruit quality of ‘Kinnow’ mandarin (Citrus reticulate Blanco.) were investigated. Kinnow mandarin was sprayed with different concentrations of boric acid viz. (0.1%, 0.2%, 0.3% and 0.4%) at fruit set stage. Leaf nitrogen (N), phosphorus (P), potassium (K), B, and zinc (Zn) along with flush length, tree height, tree spread and tree trunk diameter increased, while leaf length and leaf age showed non-significant results after foliar B application. Yield of the ‘Kinnow’ mandarin was significantly affected by foliar application of B and a significant increase in fruit weight at harvest was also observed. Soluble solid concentration (SSC): titratable acidity (TA) ratio, ascorbic acid, total sugars, total phenolic content (TPC) and total antioxidants significantly affected, while pH of juice, SSC, TA, reducing sugars and non-reducing sugars showed non- significant results.     

Quality and elemental content of citrus fruit from exposed and internal canopy positions 1

Quality and elemental content of fruit from internal tree canopies were compared with those from external canopy positions in 4 citrus varieties: ‘Kinnow’ mandarin; ‘Redblush’ grapefruit; ‘Valencia’ orange; and ‘Lisbon’ lemon. Fruit weight, total juice per fruit, peel fresh and dry weight, and rind thickness of fruit from internal canopies of all 4 varieties were significantly higher compared with external fruit. Mandarin, grapefruit, and orange fruit from external canopies had higher soluble solids and specific gravity. Fruit from internal canopies of all varieties had generally higher peel concentrations (% dry weight) of N, P and K due to a dilution effect, while the opposite condition existed in mandarin when these elements were expressed on a percent fresh weight basis. Peel Mg and S from external fruit were higher in all varieties, expressed as percentages of either dry weight or fresh weight. Nitrogen content of mandarin and orange juice and Ca content of grapefruit and lemon juice from external fruit were significantly higher compared to those from internal canopy fruit. Elimination of fruit quality and mineral variations as a result of canopy positions is recommended by the means of cultural practices.     

Mineral Concentration,Sugar Content and Yield of Iranian ‘Khatooni’ Melon Affected by Grafting,Pruning and Thinning

Macroelements in leaves and fruits, sugar of fruits, and yield of ‘Khatooni’ melon were compared with melons grafted onto rootstocks cvs. ‘Ace’, ‘Shintozwa’, and ‘ShintoHongto’, and trained into three methods: T1) no pinching and fruit thinning; T2) pinched to produce two lateral branches; and T3) pinched to two branches and all flowers and lateral branches from lower nodes thinned. Concentrations of nitrogen (N), phosphorus (P), and potassium (K) increased in leaves onto ‘Shintozwa’, whereas opposite trends observed for magnesium (Mg) and calcium (Ca). N, P, and K in leaves were significantly higher by 21.5%, 17.2%, and 18.6%, respectively in grafted. N, P and K in fruits onto ‘Ace’ and ‘Shintozwa’ were higher, with exception of Ca and Mg in non-grafted. ‘Ace’ and ‘Shintozwa’ resulted in significant increase in Khatooni yield. T3 showed the highest yield. Soluble solids concentration (SSC) was higher in non-grafted fruits. T2 produced fruits with the highest SSC.     

Fruit quality and mineral nutrient from exposed verses internal canopy positions of four scitrus varieties

>Quality and mineral content of fruit from internal tree canopies were compared with those from external canopy positions in 4 citrus varities: ‘Kinnow’ mandarin; ‘Redblush’ grapefruit; ‘Valencia’ orange; and ‘Lisbon’ lemon. Fruit weight, total juice per fruit, peel fresh and dry weight, and rind thickness of fruit from internal canopies of all 4 varieties were significantly higher compared with external fruit. Mandarin, grapefruit, and orange fruit from external canopies had higher soluble solids and specific gravity. Fruit from internal canopies of all varieties had generally higher peel concentrations (% dry weight) of N, P and K due to a dilution effect, while the opposite condition existed in mandarin when these elements were expressed on a percent fresh weight basis. Peel Mg and S from external fruit were higher in all varieties, expressed as percentages of either dry weight or fresh weight. Nitrogen content of mandarin and orange juice and Ca content of grapefruit and lemon juice from external fruit were significantly higher compared to those from internal canopy fruit. Elimination of fruit quality and mineral variations as a result of canopy positions is recommended by the means of cultural practices.     

Internal breakdown,mineral element concentration,and weight of mango fruit 1

Internal breakdown in mango fruit is a disorder often attributed to a nutrient deficiency, particularly of calcium (Ca), in the fruit. The relationship between internal breakdown in mango fruit and fruit mineral element concentrations and fresh weight was investigated. Fruit were collected weekly from a commercial orchard beginning 4 weeks after fruit set (WAFS) until the fruit were ripe. The concentrations of nitrogen (N), phosphorus (P), potassium (K), Ca, magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), and boron (B) and fresh weight of ‘Tommy Atkins’ mango fruit with and without internal breakdown were compared. Disordered fruit weighed more than healthy fruit 4 WAFS. However, when fruit were ripe there were no significant differences in fruit weight between healthy and disordered fruit. Disordered fruit contained significantly higher concentrations of N, P, Ca, and B than the healthy mango fruit, 4 WAFS. When fruit were ripe, there were no differences in N, K, Ca, Mg, Zn, Mn, Fe, and B concentrations between healthy and disordered fruit. Ripe, healthy fruit had higher Cu and lower P concentrations than ripe, disordered fruit. Internal breakdown could not be specifically linked to a Ca deficiency in mango fruit at any stage of fruit ontogeny.     

Nitrogen Application Rate and the Concentration of Other Macronutrients in the Fruit and Leaves of Gold Kiwifruit

ABSTRACT

Gold kiwifruit (Actinidia chinensis Planch. var. chinensis ‘HORT16A’, marketed as ZESPRI?' ‘HORT16A’) is an important export crop for New Zealand. Nutrient management, including the application of nitrogen (N), for ‘HORT16A’ kiwifruit has mimicked strategies for the green (A. deliciosa ‘Hayward’) cultivar, however, physiological differences between Actinidia species necessitate the development of specific nutrient regimes for ‘HORT16A’ vines. In this trial, all nutrients, except N, were applied at levels comparable to commercial practice. The Control treatment received approximately 145 kg N ha/y, and was based on estimates of total N removed each year in the harvested fruit. The Zero-N treatment vines received all nutrients except N, and the High-N treatment received double the Control, approximately 295 kg N ha/y, for two consecutive seasons. The High-N treatment represents the upper limit of N application practices in commercial ‘HORT16A’ kiwifruit production. Zero-N fruit had higher calcium (Ca) and lower N concentration than High-N fruit in both seasons. Fruit potassium (K) and magnesium (Mg) concentrations were equivalent between these treatments in both seasons. Fruit phosphorus (P) concentration throughout the season was increased in the High-N treatment in both years. Fruit sizes were not different between treatments at final harvest in Year 1, being 130.5 ± 4.13 g, 125 ± 1.49 g, and 125 ± 3.29 g for the High, Control, and Zero-N vines, respectively. Larger fruit were harvested from the High-N vines (125 ± 4.69 g) in Year 2, than from either Control (113 ± 2.03 g) or Zero-N (118 ± 1.03 g) vines. Percent fruit dry matter (DM) content was higher in the Zero-N fruit (17.2 ± 0.06, 17.2 ± 0.06, and 16.8 ± 0.14 for Zero, Control, and High-N vines) at final harvest in Year 1. But values of fruit DM for all treatments were similar in Year 2 in spite of fruit size differences between treatments. Fruit DM for all treatments was slightly higher in Year 2 than in Year 1. Differences in fruit mineral concentration and fruit maturity at harvest may have contributed to increased incidence of low temperature breakdown (LTB) in the High-N fruit in Year 1. In Year 2, when fruit DM was higher in all treatments, yellow coloration was more developed. Total fruit N concentration was lower in Year 2 for all treatments than in Year 1, and LTB was minimal and not different between treatments.

Leaves from Zero-N vines had reduced N in both years compared with Control and High-N vines. In contrast, leaf Ca and Mg concentrations were reduced in High N-vines, compared with values recorded in Zero-N vines in both seasons. Leaf K concentrations were comparable between treatments in both seasons. Leaf sulfur (S) concentration was reduced under the High-N treatment, and leaf P levels were increased under the High-N treatment in both years.

These data demonstrate that N application influences the uptake and accumulation of other mineral elements in ‘HORT16A’ kiwifruit. In order to encourage desirable nutrient concentrations in both the fruit and leaves of ‘HORT16A’ kiwifruit, a reduction in N applied is suggested, and this would have little or no detrimental effect on vine performance over two seasons. Reduced N application will also reduce nitrate leaching which is estimated at 39 kg N ha/y under the Control treatment.     

Seasonal Changes in Nutrient Concentrations of ‘Newhall’ and ‘Skagg's Bonanza’ Navel Oranges

Seasonal changes in nutrient concentrations of leaf and fruit structural parts (rind and pulp) from ‘Newhall’ (Citrus. sinensis Osbeck) and ‘Skagg's Bonanza’ (C. sinensis Osbeck) navel oranges were investigated during fruit development in two successive years. Leaf calcium (Ca), manganese (Mn), and potassium (K) concentrations were relatively constant throughout the whole season with the exception of an increase of K at stage 1, the period of fruitlet growth [before 80 days after full bloom (DAFB)], whereas the magnesium (Mg), boron (B), iron (Fe), and zinc (Zn) concentrations declined distinctly during stage 2 (80–180 DAFB), the period of fruit rapid enlargement. In rind, Ca, B, Fe, and Mn concentrations reached the greatest levels at stage 2, different from K and Mg, which increased at stage 1 and decreased thereafter. In pulp, concentrations of Ca, K, Mg, and Mn declined gradually with time, whereas a small rise in B toward the end of sampling and a clear increase of Fe at stage 2 were observed. It was suggested that ‘Newhall’ required greater B inherently in fruits as the cultivar had greater B concentrations in fruit parts and had greater rind/leaf B concentration ratios than ‘Skagg's Bonanza.’ ‘Newhall’ had relatively greater rind Ca content and exhibited Ca distribution more uniformly within its fruit parts, which probably enhanced the crack resistance.     

Nutritional Status,Yield, and Fruit Quality of “Encore” Mandarin Trees Grown in Two Sites of an Orchard with Different Soil Properties

Abstract

The nutrient status [annual fluctuation of leaf nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn)], yield and fruit quality [soluble solids concentration (SSC), titratable acids (TA), SSS/TA and juice content] of “Encore” mandarin trees cultivated in two sites of the same orchard were studied. The trees were grafted on Carrizo citrange rootstock and grown under identical conditions, apart from some soil properties. Soil B (site B of orchard) contained more K, Ca, Mg, and organic matter than soil A (site A of orchard). The patterns of annual variation of leaf nutrient concentrations were similar in both soils, although leaf concentrations of Ca, Mg, Mn, and Fe in soil A were significantly higher than those of soil boron (B), while leaf K concentrations were significantly lower. The mineral analyses of the leaves revealed some interesting antagonisms between K–Mg, K–Ca, and K–Mn. Manganese deficiency was especially limited in the trees grown in soil B. The average fruit yield per tree in soil A, on two-year basis, was significantly higher than this in soil B. The significantly higher water infiltration rate in soil B, in contrast to soil A, seemed to be the dominant factor responsible for the differences among the two sites in yielding and leaf mineral composition.     

Effects of rootstock and thinning on yield,fruit quality and elemental composition of ‘Redspur Delicious’ apple

Abstract

Influence of two rootstocks and five levels of hand thinning (fruit spacing) on yield, fruit quality at harvest and after storage, and leaf and fruit elemental composition of ‘Redspur Delicious’ apple (Malus domestica Borkh.) were studied. Trees on M.7 rootstock had a higher yield with heavier and firmer fruit at harvest than those on M.26. Trees on M.7 had significantly lower leaf and fruit N which resulted in a darker fruit color than those on M.26 rootstock. Fruit from trees on M.26 had a higher soluble solids concentration (SSC) at harvest than those on M.7. Leaf and fruit potassium (K) increased but fruit calcium (Ca) decreased with an increase in fruit spacing. Thinning fruit to 10 cm or 18 cm spacing, depending on market demand for fruit size, is recommended for improvement of fruit quality. Fruit weight and quality was improved with 18 cm fruit spacing without a significant decrease in yield, while thinning fruit further than 18 cm apart reduced yield without a significant change in the fruit weight or quality.     

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

‘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.     

Standardization of Litchi Leaf Nutrient Composition for Tissue Analysis in Sub Tropics of India

ABSTRACT

Variation in leaf nutrient composition with leaf age and position of leaflets was assessed for ‘Calcuttia’ and ‘Dehradun’ litchi cultivars under loam to sandy loam soils of north India. Leaf samples were collected from first to sixth pair of leaflets starting from the apex of terminal shoots to downward positions during December to May at monthly intervals at two locations for three successive years. The leaves were analyzed for N, P, K, Ca, Mg, Fe, Zn, Cu and Mn concentrations. In both litchi cultivars, leaf N, P, Zn and Cu contents remained more in young leaves; whereas, leaf Ca, Mg, Mn and Fe contents were observed higher in older leaves. Leaf K concentration exhibited inconsistent patterns; however, leaf K concentration in pair of leaflets on the shoot declined basipetal, being maximum in upper pair of leaflets and minimum in lower pair of leaflets. Levels of macro and micronutrients exhibited a degree of stability at second and third pair of leaflets when sampled during February–March. Leaf compositions differed significantly during active vegetative growth, flowering, and fruit development. The results revealed that 4–5 months old leaves from autumn flush at second and third pair of leaflets from the apex of terminal litchi shoots at the advent of panicle initiation (February–March) should be collected to assess the nutritional concentrations of litchi orchards under North India conditions.     

Foliar nutrient status of field grown tissue cultured and budded Apple trees

Nutrient concentrations in leaves of self‐rooted apple trees propagated by tissue culture (TC) were compared to the same cultivars budded on seedling, MM 106, and M.26 rootstock planted at two sites, Beltsville, MD and Kearneysville, WV. Leaf samples were monitored annually for 3 years after planting for N, P, K, Ca, Mg, Mn, Fe, Cu, B, Zn and Al from ‘Ozark Gold’ and ‘Stayman’ apples at both sites and ‘Northern Spy’ at Beltsville only. Leaf K and Mn concentrations tended to be higher in trees on M.26 and MM 106, while Ca was higher in TC or seedling trees. Foliar Mg was lower in trees budded on MM 106. Variation in P concentrations was greatest over years, while leaf N and Fe displayed only slight variation among rootstocks. Leaf B and Zn did not exhibit any consistent trends and Cu and Al were not affected by year, rootstock, cultivar or site.     

Nitrogen rate and source affects leaf elemental concentration and plant growth in muscadine grapes

Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), and manganese (Mn) in ‘Sterling’ muscadine grapes (Vitis rotundifolia Michaux) grown for two years in sand culture were not influenced by different N‐fertilizer sources. Leaf zinc (Zn) and copper (Cu) were higher with ammonium nitrate (NH₄NO₃)than ammonium sulfate [(NH₄)₂SO₄]. Shoot growth was greatest with NH₄NO₃. Leaf Ca, Mg, Mn, and Cu content decreased and leaf N increased as N‐fertilizer rates were raised. Plant growth was positively correlated with leaf N, but was negatively correlated with leaf Ca, Mg, Fe, Cu, and Mn content. Percent Mg in the leaves was reduced when N levels, regardless of N source, were raised from the low (1.8 mM) to the middle (5.4 mM) rate. High leaf‐N levels were correlated with lower Ca and Mg in the leaves, indicating a relationship between N fertilization and the late‐season Mg deficiency often observed in muscadine grapes.     

赣南脐橙叶片营养状况对果实品质的影响

为了探讨赣南产区纽荷尔脐橙果园叶片营养状况与果实品质的相互关系,测定了9个县（市、区）58个脐橙园叶片的矿质营养元素、果实可溶性固形物（TSS）、可滴定性酸（TA）含量和单果重（SFW）。结果表明,大部分果园叶片氮含量高于适宜范围,而所有果园叶片磷、钾含量均处于适宜范围或以上;分别有87.9%、55.2%、5.2%的果园叶片镁、钙、硫含量低于适宜范围;所有果园叶片的钼含量均处于适宜范围,铁含量处于适宜范围或以上,少量果园的叶片硼、锰含量低于适宜范围,接近1/3果园的叶片铜含量低于适宜范围,96.6%果园的叶片锌含量低于适宜范围;随着果园果实品质的提高,TSS与TA显著增加,SFW显著下降。相关性分析表明,果实TSS与叶片钾含量呈显著负相关,与镁、锌含量呈极显著正相关;SFW与叶片12个营养元素均无显著相关;TA与叶片氮含量呈显著正相关,与锰含量呈极显著正相关。因而,生产上需要重视补充镁、锌肥,适量补充钙、铜肥,合理控制氮、磷和钾肥的施用量。     

长期干旱环境对柑橘生长及养分吸收和相关生理的影响

为了揭示长期干旱环境下柑橘生长及养分吸收和相关生理响应的特点,探索长期干旱对柑橘的不良影响,以红橘(Citrus tangerina Hort.cv."Chuanju")为材料,以有灌溉条件为对照,在贵州北盘江喀斯特河谷长期自然干旱环境下连续4年观察和取样分析测定红橘的物候期,新梢和果实生长发育状况,叶片寿命,果实及叶片N、P、K、Ca、Mg、Fe、Cu、Zn、B等元素的含量,分析果实生理病害与干旱及元素含量的关系;测定与抗旱相关的形态、组织解剖及生理特征,研究红橘对长期干旱的生理响应与适应长期干旱的关系。结果表明:长期干旱环境下红橘新梢生长、开花及生理落果物候期明显推迟,果实成熟期提早,叶寿命缩短;新梢短而细且数量及叶片数减少,枯死严重;叶片革质化程度加重,叶片变小变厚,新梢叶缺N、Zn、Fe、B等症状明显;果实的鲜重、干物质质量、水分含量、种子数、果汁含量减少,春梢叶中N、P、K、Ca、Mg、Fe、Cu、Zn、B及果实的N、P、Ca、Fe、B素的含量明显降低,果皮流胶和汁胞粒化程度加重,品质下降;叶片的栅栏组织增厚,海绵组织变薄,组织紧密度和气孔密度增大,气孔变小,组织疏松度降低;在周年中叶片的脯氨酸及可溶性糖含量增加,临界水分饱和亏增大,失水速率及相对含水量和叶水势变小,Pn及Tr明显降低,夏季的WUE明显提高。红橘适应长期抗旱的能力强。在长期干旱的环境中红橘的生长节律、植株及叶片形态和寿命、叶片厚度及组织结构、气孔密度与大小、叶片的临界水分饱和亏、失水速率、相对含水量、叶水势及脯氨酸和可溶性糖含量、光合速率与蒸腾速率都发生了有利于抵御长期干旱的特异性变化。长期干旱是导致红橘树冠枝梢大量枯死、果实发育缓慢变小、种子败育、果皮流胶及汁胞粒化和果实及叶片中营养元素含量减少的主要原因。     

Fruit growth and mineral element accumulation in pacific rose™ apple in relation to orchard management factors and calyx‐end splitting

Abstract

The effect of irrigation and crop load of apple (Malus domestica Borkh cv. Pacific Rose) on the fruit growth and mineral element accumulation was investigated. Fruit growth and changes in the concentration and contents of nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and potassium (K) in the flesh of Pacific Rose? apple fruit were recorded over a growing season at the Massey University Fruit Crops Units orchard in the 1998–99 crop season. Fresh mass showed a linear growth while fruit diameter followed a curvilinear growth pattern during the growing season. Low crop load significantly increased fruit size, particularly during the final expansion phase, whereas irrigation had little effect on this attribute. Both low crop load and frequent irrigation treatments increased fruit growth rate, but the effect of the irrigation treatments fluctuated considerably during the season. The incidence of frait splitting was detected at about 20 WAFB when the fruit attained an asymmetrical growth in shape (L/D). The concentrations of N, P, Ca, Mg, and K declined throughout the sampling period. There was however, an increase in concentrations of P and K at the last harvest. The quantity of individual nutrient elements accumulated by the fruit showed an increasing trend during the season. Nitrogen accumulation however, reached maximum at 16 WAFB after which it declined until the last harvest. Fruit mineral element analysis of sound and split fruit revealed that split fruit had higher concentrations and contents of Mg and K and lower contents of Ca and P. As a result, the ratios of Ca: Mg and Ca: K were lower in split fruit as compared with sound fruit.     

Correlations Between Soil Exchangeable Ca2+, Mg2+, K+ and Foliar Nutrient Concentrations in Mature Biological Olive Groves (Olea europaea L., cv. ‘Chondrolia Chalkidikis’)

Leaf and soil samples were taken and analyzed from two mature biological olive groves (Olea europaea L., cv. ‘Chondrolia Chalkidikis’), in Thessaloniki, Macedonia, Northern Greece, in order to determine the correlations between soil exchangeable cations and foliar calcium (Ca), magnesium (Mg) and potassium (K) concentrations, and the interrelations among leaf nutrients. Τhe nutritional requirements of trees for both biological groves were exclusively based on patent kali supply and nutrient recycling (via pruning material and weed cut recycling). Foliar K, Ca and Mg were positively correlated with soil exchangeable K, Ca and Mg, in the 40–60 cm layer, then in the 20–40 cm layer. Synergistic uptake mechanisms among Ca²⁺, Mg²⁺ and K⁺ probably exist. Leaf N was negatively correlated with foliar K, and positively with leaf Ca, Mg and manganese (Mn). Foliar P was negatively correlated with leaf Ca, Mg and Mn, while foliar Ca was positively correlated with leaf Mg and Mn. Foliar Mg was positively related with leaf Mn. High phosphorus (P) may decrease leaf Ca, Mg and Mn. Enhanced Ca may increase leaf Mg and Mn, while high Mg may also enhance foliar Mn. Finally, based on the determination of foliar nutrient concentrations, the nutritional requirements of olive trees in Ca, Mg, K, P, Fe, Zn were sufficiently (or over-sufficiently) satisfied. However, additional organic fertilization is needed, in order to achieve optimum levels of N, B and Mn (since their foliar concentrations were slightly insufficient). The correlations between leaf and soil exchangeable Ca, Mg and K, as well as among foliar nutrients should be taken into consideration, in order to achieve successful organic fertilization for mature biological olive groves, and to avoid nutritional imbalances and disorders.     

Influence of humic acid and salicylic acid on yield,fruit quality,and leaf mineral elements of strawberry (Fragaria × Ananassa duch.) cv. Camarosa

A greenhouse experiment was conducted to evaluate the effects of foliarly-applied Humic Acid (HA) and Salicylic Acid (SA) on strawberry (Fragaria × Ananassa cv. Camarosa). On average, HA applications, regardless of concentration, increased overall yield, Soluble Solids Concentrations (SSC), Titratable Acidity (TA), vitamin C, red tone (a*), leaf potassium (K), phosphorus (P), calcium (Ca) and magnesium (Mg) while had no effect on pH and fruit luminosity (L*). In contrast, fruit from the untreated control tended to have higher Total Antioxidant Capacity (TAC) and SSC: TA ratio than HA-treated plants. Application of SA significantly increased yield, vitamin C, SSC, SSC: TA ratio, TAC, a*, leaf P and Ca while had no effect on TA, fruit size, L* and pH. In general, application of either HA at 25 mg L¹ or SA at 2 mM resulted in better strawberry performance than did other rates of these compounds.