Seasonal Changes of Mineral Nutrients in Fruit and Leaves of ‘Newhall’ and ‘Skagg's Bonanza’ Navel Oranges

In southern Jiangxi province of China, ‘Newhall’(Citrus sinensis Osbeck) navel orange presented a conspicuous symptom of boron (B) deficiency in mature leaves, whereas B deficiency symptoms were not manifested on ‘Skagg's Bonanza’(C. sinensis Osbeck) navel orange. In this study, changes in concentrations of B, calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) were comparatively investigated in the structural parts of the fruit (rind and pulp) and leaves (old leaves from last season and spring-flush leaves from current year) of ‘Newhall’ and ‘Skagg's Bonanza’ navel orange during the growing season. Two peaks of B concentrations were observed in the rind of the two cultivars during fruitlet growth and fruit enlargement, respectively. Boron concentrations were relatively high in the rind during fruitlet growth, and then decreased in both rind and pulp, whereas, during middle and late fruit enlargement significant increases were found for B in both rind and pulp of the two cultivars. Boron concentrations in old leaves of ‘Newhall’ decreased progressively and remained relatively low, whereas that of ‘Skagg's Bonanza’ was relatively high and changed slightly as the season progresses. Both Ca and K concentrations were above the critical threshold values, while their dynamics were reverse to that of B in fruit and leaves during certain times. Old leaf Mg concentrations of samples at 140 days after full bloom from the two cultivars and spring-flush leaves from ‘Newhall’ were below the threshold limit for sufficiency. In addition, Mg in old leaves was much lower from ‘Newhall’ than from ‘Skagg's Bonanza’. Spring-flush leaf concentrations of Mn and Zn and Mn concentrations in old leaves from ‘Newhall’ were relatively lacking during middle and late season, which accelerated the occurrence of B deficiency symptoms on mature leaves of ‘Newhall.’     

Optimum Nutrient Level on Growth,Flowering, and Rhizome Production in Curcuma

ABSTRACT

This study investigated the effect of liquid fertilizer treatments on growth, flowering, leaf mineral content, and rhizome production during forcing of Curcuma alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’. Plants were irrigated with 200 mL of 1.3 g L^?1 of 15 nitrogen (N) -7 phosphorus (P) -14 potassium (K) water soluble fertilizer at 0, 1.3, 2.7, 4.0, 5.3, or 6.6 g L^?1 weekly. Days to flower, flower stem length, and leaf length were recorded, the mineral contents in leaves were analyzed, and the number of rhizomes with tuberous roots were recorded at harvest. Flowering of the first inflorescence in both C. alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’ was significantly delayed when plants received 6.6 g L^?1 fertilizer as compared to the control plants. The number of rhizomes with more than 4 tuberous roots was highest when plants received 2.7 g L^?1 fertilizer. No medium-sized rhizomes with more than seven tuberous roots were produced when ‘Chiang Mai Pink’ plants received 0, 4.0, 5.3, and 6.6 g L^?1 fertilizer. Based on the production of rhizomes with four to six tuberous roots, optimum concentration of 15N -7P -14K water soluble fertilizer is 2.7 g L^?1 for C. alismatifolia ‘Chiang Mai Pink’ and 1.3 to 4.0 g L^?1 for C. thorelii ‘Chiang Mai Snow’. Although high boron content occurred only in the outer part of the second leaf when fertilizer concentrations were increased, leaf-margin burn (LMB) symptoms were not observed in both species and this could not be related to the production of rhizomes.     

Aluminum toxicity in tomato. Part 1. growth and mineral nutrition

Aluminum (Al) toxicity was studied in two tomato cultivars (Lycopersicon esculentum Mill. ‘Mountain Pride’ and Floramerica') grown in diluted nutrient solution (pH 4.0) at 0, 10, 25, and 50 μM Al levels. In the presence of 25 and 50 μM Al, significant reduction was found in leaf area, dry weight, stem length, and longest root length of both cultivars. Growth of ‘Floramerica’ was less sensitive to Al toxicity than growth of ‘Mountain Pride’. Elemental composition of the nutrient solutions were compared immediately after the first Al addition and four days later. The uptake of micronutrients copper (Cu), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B), and iron (Fe) from the nutrient solution was reduced in both cultivars with increasing Al levels. Nutrient solution Al gradually decreased in time for every treatment; less in cultures of ‘Floramerica’ than in ‘Mountain Pride’. Aluminum treatments decreased the calcium (Ca), potassium (K), magnesium (Mg), Mn, Fe, and Zn content in the roots, stems, and leaves. Aluminum treatment promoted the accumulation of P, Mo, and Cu in the roots, and inhibited the transport of these nutrients into stems and leaves. At 25 and 50 μM levels of Al, lower Al content was found in the roots of cv. “Floramerica’ than in the roots of cv. ‘Mountain Pride’.     

Aluminum toxicity in tomato. Part 2. leaf gas exchange,chlorophyll content,and invertase activity

The effect of aluminum (Al) toxicity on leaf gas exchange, leaf chlorophyll content, and sucrose metabolizing enzyme activity of two tomato cultivars (Lycopersicon esculentum Mill. ‘Mountain Pride’ and ‘Floramerica') was studied to determine the mechanism of growth reduction observed in a related study (Simon et al., 1994, Part 1). Plants were grown in diluted nutrient solution (pH 4.0) with 0, 10, 25, or 50 μM. Al for 16 days. Leaf gas exchange was reduced 2–3 fold in both cultivars as Al concentration increased. Gas exchange of ‘Mountain Pride’ was more sensitive to Al toxicity than ‘Floramerica’, agreeing with growth responses observed. Reductions in carbon dioxide (CO₂) assimilation rate appeared to be due to nonstomatal factors in ‘Floramerica’, but stomatal and non‐stomatal limitations in ‘Mountain Pride’. Chlorophyll content of leaves was not affected by Al. Acid invertase (AI) and neutral invertase (NI) activity of roots responded consistently to Al concentration in both cultivars. Root AI and NI activity decreased to a greater extent for ‘Mountain Pride’ than for ‘Floramerica’.     

Toxicity symptoms and tissue levels associated with excess boron in pear trees

Abstract

High levels of B were applied to the soil around ‘Bartlett’ and ‘d'Anjou’ pear trees in a non‐irrigated orchard. B levels in the soil profile and in the flowers, leaves and fruit were monitored for 6 years. Levels of B in the soil dropped to below 2 ppm within 5 years following the application. By then all visible symptoms of toxicity had disappeared. The B content of ‘Bartlett’ tissues was always higher than that of ‘d'Anjou’ and the symptoms of toxicity were more severe. Under conditions of this research, full bloom blossom cluster levels and levels in the fruit at harvest time were better indicators of toxicity than were the levels in leaves. Boron levels in blossom clusters above 90 and 115 ppm and in fruit above 55 and 45 ppm for ‘d'Anjou’ and ‘Bartlett’ pears respectively were considered to be toxic.     

Acute boron toxicity in Begonia X hiemalis ’Schwabenland Red‘

Abstract

Boron toxicity was induced in Begonia X hiemalis Fotsch ‘Schwabenland Red’ by successive applications of 1.0 mM H₃BO₃ to the root medium. Treatments were initiated at progressive stages of growth. Leaf injury occurred initially on mature leaves. Symptoms progressed from mild chlorosis of the leaf margins to an eventual necrosis extending inwards 3 to 5 mm from the leaf margin. Mean concn of B in canopy leaves of plants exhibiting incipient symptoms of B toxicity ranged from 125 to 258 ppm. Older plants tended to exhibit B toxicity symptoms at lower foliar concn of B than younger plants.     

Rootstock Effect on Nutrient Concentration of Sweet Cherry Leaves

The present investigation aimed to study the leaf mineral composition of sweet cherry trees on different rootstocks, since the literature data on uptake efficiency of different rootstocks is inconsistent. Results confirmed the different uptake efficiency of rootstocks. The efficiency of ‘GiSelA 6’ root is emphasized in uptake and supply of leaves with nitrogen (N), phosphorus (P), potassium (K), zinc (Zn), boron (B), and manganese (Mn), but trees on this rootstock tend to develop calcium (Ca), magnesium (Mg), and copper (Cu) deficiencies. The Prunus mahaleb rootstocks on calcareous sandy soil are efficient supplier of N, P, K, Ca, Mg, Fe, and Cu, but this root tends to develop Zn, B, and Mn deficiencies. Prunus avium seedling as rootstock proved to be less efficient in supply of leaves by N, P, K, Ca, and Cu. Prunus fruticosa ‘Prob’ root showed tendency in developing several leaf nutrient deficiencies. The applied fertilizer program led to low nutrient levels or even deficiency symptoms in leaves.     

Protea Nutritional Problems and Soil Nutrient Status in Norton-Darwendale and Juliasdale Farming Areas,Zimbabwe

A study was conducted from November 2000 to February 2001 to establish causes of poor protea plant growth in the Juliasdale and Norton-Darwendale commercial farming areas of Zimbabwe. Soil and leaf samples from farmer-perceived “deficient” and “normal” areas were analyzed. Soils perceived by farmers to be deficient had lower levels of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) compared with the normal soils. In Juliasdale, all cultivars from perceived-deficient samples had lower levels of zinc (Zn) in leaves compared with normal leaves. Leucospermum cultivar ‘Tango’ and Protea cultivar ‘Moonshine’ also had low levels of P and Zn in the deficient plants compared with the normal plants. In Norton-Darwendale, the Protea cultivar ‘Moonshine’ had lower levels of nitrogen (N), P, K, and boron (B) in perceived-deficient samples compared with normal samples. Soil-analysis data were generally comparable to leaf-analysis data, indicating the potential use of leaf analysis to determine nutritional requirements of proteas.     

Salicylic Acid–Induced Growth and Biochemical Changes in Salt‐Stressed Wheat

The interactive effect of salicylic acid and sodium chloride (NaCl) salinity on wheat (Triticum aestivum L.) cv. ‘Inqlab’ (salt‐sensitive) and cv. ‘S‐24’ (salt‐tolerant) was studied in a sand‐culture pot experiment in a net house. Wheat seeds soaked in water and 100 ppm salicylic acid solution for 6 h were sown in sand salinized with 0, 50, and 100 mM NaCl. Pots were irrigated with quarter‐strength Hoagland's nutrient solution. Fourteen‐day‐old seedlings were harvested, and growth parameters (leaf and root length, leaf and root dry weight) were recorded. Chlorophyll a and b content; soluble sugar (reducing, nonreducing, and total sugars) content; nitrate (NR) and nitrite reductase activity (NiR); soluble proteins, and total soluble amino acid content of fresh leaves were determined. Sodium chloride salinity significantly reduced growth parameters. Salicylic acid treatment alleviated the adverse salinity effect on growth. Salinity decreased the chlorophyll a and b content and chlorophyll a/b ratio in both varieties, but a decrease in the chlorophyll a/b ratio was less in salt‐tolerant wheat variety (‘S‐24’), which could be a useful marker for selecting a salt‐tolerant variety. Salinity (NaCl) stress considerably increased the accumulation of reducing sugars, nonreducing sugars, and total soluble sugars in leaves of 14‐day‐old wheat seedlings of both varieties. The salt‐tolerant variety (‘S‐24’) accumulated a higher sugar content, which also could be a useful marker for selecting a salt‐tolerant variety for slat‐affected areas. Salinity caused a reduction in nitrate reductase and nitrite reductase activity. The salt‐tolerant variety (‘S‐24’) showed resistance to a decrease of nitrate reductase activity under salinity. This could be a useful criterion for selecting salt‐tolerant varieties. In response to salinity, wheat seedlings accumulated soluble proteins and amino acids, which might reflect a salt‐protective mechanism.     

Salt tolerance of two lemon scions measured by leaf chloride and sodium accumulation

Effects of salinity on growth, ion content, water relationships, and chlorophyll and proline levels were measured on one‐year‐old ‘Verna’ and ‘Fino’ lemon (Citrus limon [L] Burm. F.) scions budded to either Sour orange (C. aurantium L.) or macrophylla (C. macrophylla Wester) rootstock. Trees were grown in nutrient solutions containing 2 (control), 40, or 80 mol m^‐3 NaCl for 75 days.

Growth of all combinations was reduced by salinity, but this effect was greater for both scions budded on macrophylla. Leaf chloride and sodium concentrations were lower in both scions budded on Sour orange. Leaf salt concentration was scion dependent. Leaves of ‘Fino’ lemon had higher levels of both chloride and sodium than did leaves of ‘Verna’ lemon, regardless of the rootstock considered.

Despite an accumulation of chloride and sodium in the leaves of salinized trees, leaf water potential and leaf water content increased above the control level. However, stomatal conductance declined in all rootstock/scion combinations.

Chlorophyll contents were markedly reduced by salt treatment; greater reductions were seen in ‘Fino’ lemon than in ‘Verna’ lemon on both rootstocks. Chlorophyll reductions were highly correlated with both chloride and sodium concentrations in the leaves. Free proline increased with salinity in leaves of both scions budded on Sour orange, but was unaffected on macrophylla.

Differences in the parameters determined in response to salinity were attributed to the different capacity of each specific rootstock/scion combination to import chloride and sodium into leaves.     

Effect of Plant Age and Humidity on Development of Bacterial Wilt of Forage Grasses

Abstract

The effect of plant age on the development of bacterial wilt of forage grasses was studied by dipping cut roots of Lolinm perenne L. cv. ‘Svea’ in a suspension of Xanthomonas campestris pv. graminis. The effect of humidity on disease development was studied by cutting leaves with scissors dipped in inoculum, and by spraying inoculum onto unwounded leaves. Young plants were more susceptible to the pathogen than old ones. X.c.graminis was easily isolated from young leaves and tillers, especially from the leaf bases. Disease symptoms were most severe at low humidity. However, high humidity is necessary for infection to take place through stomata and hydathodes.     

Salt tolerance evaluation of nine indigenous Greek olive cultivars

The present work was aimed to evaluate nine Greek olive (Olea europaea L.) cultivars for tolerance to sodium chloride (NaCl) salinity, most of which have never been evaluated or considered to be extinct, in order to be used in the future as olive rootstocks in areas with salt toxicity problems.One-year old, self-rooted trees of the cultivars ‘Aetonicholia Kynourias,’ ‘Arvanitolia Serron,’ ‘Ntopia Atsicholou,’ ‘Koroneiki,’ ‘Lefkolia Serron,’ ‘Ntopia Pierias,’ ‘Petrolia Serron,’ ‘Smertolia,’ and ‘Chrysophylli’ were subjected to 0, 50, 100, and 200 mM NaCl, for six months, in nutrient solution pot experiment. The experiment was conducted as a completely randomized factorial design with four replications (of one tree), with the factors being the cultivar (nine levels) and the salt concentration (four levels). According to plant growth parameter results, ‘Arvanitolia Serron’ followed by ‘Lefkolia Serron’ were found to be the most salt tolerant cultivars to growth reduction. The same cultivars accumulated less sodium (Na) and chlorine (Cl) in the leaves by retaining more ions in the roots. Moreover, ‘Arvanitolia Serron’ was able to maintain high potassium (K) levels and K/Na ratio in younger leaves under salinity.     

Growth of Brazilian Cotton Cultivars in Response to Soil Applied Boron

ABSTRACT

The growth of cotton (Gossypium hirsutum L.) was evaluated in a 6 × 5 factorial experiment with 6 boron (B) levels (0.0, 0.5, 1.0, 1.5, 2.0, and 3.0 mg dm^?3), 5 cultivars (‘CNPA 8H’, ‘BRS Aroeira’, ‘BRS Antares’, ‘BRS Sucupira’, ‘BRS Ipe’), and 3 replications. As B increased in the soil, leaf B concentrations increased linearly in ‘BRS Aroeira’ and ‘CNPA 8H’, and quadratically in ‘BRS Ipe’ and ‘BRS Sucupira’. The concentrations of B in the leaves and in the soil increased with the B increasing in the soil. The agronomic characteristics evaluated showed ‘BRS Aroeira’ and ‘BRS Sucupira’ responding more and BRS responding less to the B doses applied. The variation in the effFiciency of B utilization was: ‘BRS Aroeira’ > ‘CNPA 8H’ = ‘BRS Antares’ > ‘BRS Sucupira’ > ‘BRS Ipe’. Cultivar ‘BRS Aroeira’ had the greatest potential to respond positively to the addition of B to the soil.     

Urea retention and uptake by avocado and apple leaves

Solution retention by avocado (Persea americana cv. Fuerte) and apple (Mallus domestica Burkh. cv. Anna) leaves was measured by weight gain of detached leaves after dipping them in solutions of two surfactants and by analysis of various concentrations of urea retained at zero time on surfaces of attached leaves. Linear regression equations were calulated, relating leaf area and retention of solution. The slope of the equation represents the retention of solution on the leaf surface, and its intercept represents the value retained on the leaf margin. Solution retained on leaf surface was 2.5–2.6 and 5.4–6.4 mg/cm² for ‘old’ avocado and apple leaves, respectively. Retention on the serrated leaf margin of the apple was greater than on the smooth margin of the avocado. The abaxial leaf surfaces retained approximately 62% and 83% of the total solution retained by the avocado and the apple leaves, respectively.

The rate of urea uptake was proportional to the applied concentration and reached in avocado 65–85% within 2–5 days and over 90% in apple within 2 days. The rate of urea uptake by avocado was similar on ‘Young’ and ‘old’ leaves, similar from either Triton X‐100 or L‐77 surfactants, and similar through abaxial and adaxial surfaces. The nitrogen enrichment from foliar application of urea was related to retention and threshold of phytotoxicity rather than to rate of uptake. Older leaves of avocado showed some phytoxicity to 4% urea. Young leaves were damaged by repeated 2% application and flowers by 0.5–1.0%.

The actual nitrogen enrichment in avocado, which could be predicted accurately from measurement of urea retention, was 43% following three successive applications of 3% urea in 12 days.     

Salinity and Defoliation Effects on Soybean Growth

An experiment was conducted to determine if salinity stress alters the response and tolerance of soybean to defoliation. Four soybean [Glycine max(L.) Merr.] cultivars (‘Tachiutaka,’ ‘Tousan 69,’ ‘Dare’ and ‘Enrei’) in a growth chamber were exposed to two salinity treatments (0 and 40 mM NaCl) and two defoliation treatments (with and without defoliation). The interactive effects of salinity stress and defoliation on growth rate, leaf expansion, photosynthetic gas exchange, and sodium (Na⁺) accumulation were determined. The decrease in growth rate resulting from defoliation was more pronounced in plants grown under salinity stress than in those grown without the stress. Without salinity stress, defoliated plants of all four cultivars had leaf-expansion similar rates to those of the undefoliated ones, but the photosynthetic rates of their remaining leaves were higher than those of undefoliated plants. However, with salinity stress, defoliated ‘Tachiutaka’ and ‘Tousa 69’ had lower leaf expansion and photosynthetic rates than undefoliated plants. For cultivars ‘Dare’ and ‘Enrei,’ the defoliated plants had leaf-expansion rates similar to undefoliated ones, but the photosynthetic rate of the remaining leaves did not increase. Except for cultivar ‘Dare,’ defoliated plants grown under salinity stress had higher Na⁺ accumulation in leaves than undefoliated ones, and this result may be related to slow leaf expansion and photosynthesis. Salinity stress negatively affects soybean response and tolerance of defoliation, and the effects varied according to the salt tolerance of the cultivar.     

Critical toxic concentrations of boron are variable in barley

The use of leaf symptoms and plant analysis in diagnosing and predicting yield depressions associated with boron (B) toxicity in barley was examined. Barley (Hordeum vulgare L., cv. Stirling) was grown in pots of a sandy soil to which six levels of B were added. With increasing additions to the soil, B accumulated in the older leaves, increasing leaf injury and senescence. Leaf injury symptoms at high levels of B supply appeared in time well before dry mailer was depressed. Root weight was decreased more than shoot weight. Grain filling was affected only at severe levels of B toxicity. Critical toxic concentrations (CTC) of B in shoots were found to vary between approximately 40 and 150 μg, depending on the stage of plant growth at the lime of B analysis and the yield parameter chosen. A distinction is made between CTC values of B that are diagnostic or prognostic.     

Effect of magnesium on early taro growth

Abstract

Little research has been conducted on magnesium (Mg) nutrition of taro [Colocasia esculenta (L.) Schott cv. ‘Bun Long']. In this study, we evaluated the effects of varying levels of Mg (0.0, 0.05, 0.1, 0.2, 0.4, and 0.8 mM) on taro plants grown hydroponically for 33 days. Magnesium treatment effects were evaluated for dry matter biomass, leaf area, and N, P, K, Ca, Mg, Na, Mn, Fe, Cu, Zn, and B concentrations of old and young leaves. Dry matter of leaves (young, old, and total), roots, corms, petioles, and total biomass were significantly higher in all plus‐Mg treatments than in the zero‐Mg treatment. These same biomass parameters were not different among treatments with Mg (0.05 to 0.8 mM). Leaf area (young, old, and total) did not differ significantly with varying levels of Mg. A quadratic model described the relationship between Mg levels in leaves and solution Mg (r² = 0.99). Young and old leaf Mg concentrations did not differ. Total leaf Mg concentration ranged from 0.07% to 0.42% for the lowest and highest Mg levels in solution, respectively. Leaf Mg effects on total leaf DM was best fit using segmented regression (r² = 0.95), with a corresponding critical leaf Mg concentration (95% of maximum predicted leaf DM) of 0.14%. No significant interactions were observed between Mg and other mineral nutrients. Critical leaf Mg concentration is based on the vegetative growth stage of taro and could be a key index for taro producers who emphasize vegetable leaf, rather than corm production.     

Growth and phosphorus accumulation in tomato cultivars 1

Abstract

The distribution patterns of dry matter and P in field‐grown tomato ‘Campbell‐37’, ‘Knox’, and ‘Tipton’, (Lvcopersicon esculentum mill), were determined from 25 days after emergence to harvest. Dry weight accumulation was about the same for the 3 cultivars up to 55 days after plant emergence. From 55 to 75 days, ‘Knox’ accumulated more total plant dry weight than either ‘Tipton’ or ‘Campbell‐37’, largely due to an accelerated fruit accumulation rate during this period. In the 75 to 105 day interval, dry weight accumulation by ‘Knox’ was less than ‘Campbell‐37’ or ‘Tipton’. Fruit accumulation, as indicated by fruit number increase, was during the 45 to 75 day period for ‘Knox’, the 55 to 75 day period for ‘Tipton’, and the 55 to 85 day period for ‘Campbell‐37’. ‘Knox’ and ‘Tipton’ had a faster fruit ripening rate than ‘Campbell‐37’. The total ripe fruit yields, for single and multiple harvests, were 36.7% and 28.6% respectively, higher in ‘Campbell‐37’ than in ‘Knox’. Phosphorus concentration of stem, leaf, and cluster tissues decreased over the season for the 3 cultivars. Phosphorus concentrations of leaves decreased from 0.49% to 0.16% as plant development progressed from seedling stage to ripe fruit harvest. Phosphorus in the vegetative portion of the tomato plant at final harvest represented only about 10% of the total P accumulated. The plant efficiency with respect to P accumulation decreased from an early stage of plant development as the relative growth rate of the plant declined.     

Sorghum genotype differences to leaf “red‐speckling”; induced by phosphorus 1

Sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solutions, sand, and soil under greenhouse or growth chamber conditions developed a lower leaf “red‐speckling”; which was induced by phosphorus (P). As P in solution increased, the intensity of the “red‐speckling”; increased. Although the severity of “red‐speckling”; was not directly related to leaf P concentration, leaves with more severe symptoms had higher P concentrations. KS35, ‘Martin’, and ‘Plainsman’ developed severe symptoms, CK60‐Korgi, SC369–3‐1JB, and TX415 developed intermediate symptoms, and NB9040 developed no symptoms when grown at relatively low levels of P (10 to 20 umol per plant). Organic sources of P induced more severe “red‐speckling”; than inorganic sources. The severity of “red‐speckling”; induced by P compounds followed the sequence of gyceryl > ethyl ammonium = phenyl > potassium dihydrogen > calcium meta > calcium dibasic > calcium tribasic > ferric > calcium pyro = ferrous = aluminum phosphates. “Red‐speckling”; on young sorghum leaves may be caused by excess P. This excess or toxic P “red‐speckling”; occurred at P levels lower than had normally been considered or expected.     

Relationships between leaf and fruit minerals and fruit quality attributes of apples grown under northern conditions

Field experiments were conducted during 1994–1995 in seven apple (Malus spp.) orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Transparente Blanche’, ‘Samo’, ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Åkerö’, ‘Aroma’, and ‘Lobo’. Leaf samples from branches bearing fruits (BF) and not‐bearing fruits (BNF) were collected two times during the growing seasons. Fruit samples were picked about one week before commercial maturity. Macronutrient concentrations in fruits and leaves, fruit diameter and juice pH, titratable acidity (TA) and soluble solids concentrations (SSC) were determined. Leaf nitrogen (N), phosphorus (P), and potassium (K) were higher, but calcium (Ca) and magnesium (Mg) were lower in BNF. Branch types (BF and BNF) were closely related in leaf N, P, and Ca, but not in leaf K and Mg at the first sampling time. Fruit N, P, K, and Mg were closely related to each other but not to fruit Ca. Mean fruit N and Ca and leaf P and Mg were low compared with the recommended levels. Relationships between fruit and leaf nutrient concentrations were found only in P and Mg. Fruit diameter increased and juice SSC decreased with increasing leaf N concentration. Fruit P declined with increasing fruit diameter and juice TA increased and SSC/TA decreased with increasing leaf P and Ca concentrations.