Physiological Disorder of Rice Associated with High Levels of Iron in Growth Medium

Three rice (Oryza sativa L.) varieties viz. ‘CR 683‘, ‘Budumoni’ “Budumoni”, and ‘Akisali’ were grown in sand culture in a greenhouse with three levels of iron (Fe) in nutrient solutions viz., 0.045 (control), 5.34, and 7.12 mM Fe to study the effects of iron on physiology of rice seedling growth. Shoot length, root, and shoot dry weights were reduced significantly by higher levels of Fe in the medium. Results of leaf bronzing have revealed higher bronzing score in the seedlings grown at 7.12 mM Fe in the growth medium. Occurrence of bronzing was severe in varieties ‘CR683’ and ‘Akisali’. Variety ‘Budumoni'maintained higher leaf chlorophyll content, nitrate reductase activity and total soluble protein in the leaves at 5.34 and 7.12 mM Fe. Higher concentration of iron in the nutrient medium exerted an inhibiting effect on the concentration and content of almost all the macro and micronutrients in the root and shoot. Higher Fe and nitrogen (N) contents and lower phosphorus (P), potassium (K), manganese (Mn), copper (Cu), and zinc (Zn) were determined in roots and shoots in plants grown in medium supplied with 7.12 mM Fe. The variety ‘Budumoni’ “Budumoni” performed relatively better in comparison to other tested varieties at 7.12 mM Fe in the growth medium. ‘Budumoni’ “Budumoni” can be considered a suitable rice variety to use in the rice-breeding programme for Fe toxicity tolerance in acid soils of Assam.     

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.     

DIFFERENTIAL RESPONSE OF TWO OLIVE CULTIVARS TO EXCESS MANGANESE

The response of three-month-old rooted cuttings of the olive cultivars ‘Picual’ and ‘Koroneiki’ grown in black plastic bags containing perlite as a substrate to excess manganese (Mn) (640 μM) was studied. The rooted cuttings were irrigated with 50% modified Hoagland nutrient solution. At the end of the experimental period, which lasted 130 days, the total fresh and dry weights, as well as the shoot elongation of ‘Picual’ plants were significantly reduced under excess Mn (640 μM), compared to the control plants (2 μM), whereas the growth of ‘Koroneiki’ plants was similar in both Mn treatments. The tolerance index, which is derived from the ratios between the plant growth data of different treatments and the control one, of ‘Picual’ plants to excess Mn was about half of this of ‘Koroneiki’ plants. In both cultivars, the concentrations of Mn in various plant parts (root, basal stem, top stem, basal leaves, top leaves) were significantly increased as Mn concentration in the nutrient solution increased. Furthermore, in the 640 μM Mn treatment, 2 to 2.5-fold greater Mn concentrations were recorded in almost all plant parts of ‘Koroneiki’, than those of ‘Picual’. Similar results were recorded with regard to the total Mn content per plant (‘Koroneiki’ absorbed much more Mn from the nutrient solution than ‘Picual’). On the other hand, excess Mn negatively affected the absorption of iron (Fe), calcium (Ca), magnesium (Mg), phosphorus (P), zinc (Zn), and boron (B), depending on the olive cultivar. In both cultivars, while the Mn use efficiency was significantly decreased under excess Mn conditions, the nutrient use efficiencies of P, Ca, and Fe were significantly increased, compared to the control plants (2 μM Mn). It was also found that excess Mn resulted in a significant increase of stomatal conductance and transpiration rate of both cultivars, whereas the photosynthetic rate was significantly increased only in ‘Koroneiki’. In ‘Picual’, similar photosynthetic rates were recorded in both Mn treatments. The measurement of the various chlorophyll fluorescence parameters, F_v/F_m and F_v/F₀ ratios, revealed that the functional integrity of photosystem II (PSII) of photosynthesis was not affected due to excess Mn, irrespectively of the cultivar. In conclusion, although ‘Koroneiki’ tissues had much higher Mn concentrations than those of ‘Picual’, the parameters related to the growth and photosynthetic performance of plants indicates that the internal tolerance of ‘Koroneiki’ tissues to excess Mn was higher than this of ‘Picual’.     

Effects of High Boron Concentration and Scion-Rootstock Combination on Growth and Nutritional Status of Olive Plants

Own rooted olive plants (Olea europaea L.) of the cvs. ‘Megaritiki’ (M), ‘Chondrolia Chalkidikis’ (C), ‘Amfissis’ (A), ‘Kalamon’, ‘Koroneiki’, ‘Agiou Orous’, and wild olives, as well as the scion x rootstock combinations CxC, MxC, MxM, AxM, CxM, AxA, and CxA were irrigated with a nutrient solution containing 10 mg boron (B)/L for two months. In all the own rooted plants and in the rootstock—scion combinations of the same cultivar stem growth rate was decreased due to high B. The lowest B concentration in leaves and roots was found in ‘Kalamon’ and wild olives, respectively. ‘Megaritiki’ had higher leaf B concentration when grafted on ‘Megaritiki’ or ‘Chondrolia Chalkidikis’ compared to own rooted plants. The same cultivar as own rooted plant had higher root B concentration than as rootstock of the other tested cultivars.     

Dynamics of macronutrients in olive leaves

The study aims to track the dynamics of the olive leaf nitrogen (N), phosphorus (P) and potassium (K) for five olive varieties under drip irrigation in farmer's fields in central Morocco. Leaf sampling was done every month from May 2014 to April 2015. Leaf macronutrients contents showed variation over time. Olive leaves have maintained the same N content throughout the study period indicating a continuing olive uptake of nitrogen. Higher leaf P absorption was observed during flowering and fruit magnification periods indicating the important P needs of olive during these periods. Olive leaf K levels were higher from September to December indicating the high K needs of olive. No variety effect was revealed on the leaf N, P and K contents. Very highly significant differences were found between the leaf N and K levels measured at different sampling periods. The leaf P concentration was statistically equal in all measuring periods.     

Effect of Cadmium and Iron on Rice (Oryza Sativa L.) Plant in Chelator-Buffered Nutrient Solution

ABSTRACT

To better understand the mechanisms responsible for differences in uptake and distribution of cadmium (Cd), nutrient-solution experiments were conducted with different varieties of rice (Oryza sativa), ‘Khitish’ and ‘CNRH3’. The plants were grown in a complete nutrient solution with different levels of pCd (-log free Cd⁺² activity) and pFe [-log free iron (Fe⁺²) activity]. The required concentrations of chelating agent and metals were determined using a computerized chemical equilibrium model such as Geochem-PC. Experimental treatments included a combination of four pCd activity levels (0, 7.9, 8.2, and 8.5) applied as Cd (NO₃)₂ 4H₂O, and two pFe activity levels (17.0 and 17.8) applied as FeCl₃. The application of both Cd and Fe in solution culture significantly affected plant growth, yield, and Cd accumulation in plant tissue. In general, yield of rice was decreased by an increase in amount of solution Cd; however, yield response varied among the cultivars. At the 7.9 pCd level, yields of rice cultivars ‘Khitish’ and ‘CNRH3’ were reduced to 69% and 65%, respectively, compared with control plants. Root Cd concentrations ranged from 2.6 mg kg^?1 (control plants) to 505.7 mg kg^?1 and were directly related to solution Cd concentrations. In rice plants, Cd toxicity symptoms resembled Fe chlorosis. Differential tolerance of varieties to phytotoxicity was not readily visible, but a significant interaction of substrate Cd and variety was obtained from dry-matter yields. Significant interactions indicated that response of tissue Cd concentration, plant Cd uptake, and translocation of Cd to the aerial parts were dependent on variety as well as substrate Cd. Uptake of Cd by roots was significantly higher than by shoots. Higher Cd uptake by rice plants decreased the uptake of other beneficial metals.

The effect of Cd and Fe on the rate of phytometallophore release was also studied in the nutrient solution. Among the rice genotypes, ‘Khitish’ was the most sensitive to Cd toxicity. In both genotypes, with the onset of visual Cd-toxicity symptoms, the release of phytometallophore (PM) was enhanced. Among the rice varieties, ‘Khitish’ had the highest rate of PM release. Treatments with the metal ions studied produced a decrease in chlorophyll and enzyme activity. A decrease in concentrations of chlorophyll pigments in the third leaf was observed due to the highest activity level of Cd (pCd 7.9). Activities of enzymes such as peroxidase (POD) and superoxide dismutase (SOD) are altered by toxic amounts of Cd. Changes in enzyme activities occurred at the lowest activity of Cd (pCd 8.5) in solution. Peroxidase activity increased in the third leaf. Results showed that in contrast with growth parameters, the measurements of enzyme activities may be included as early biomarkers in a plant bioassay to assess the phytotoxicity of Cd-contaminated solution on rice plants. Evidence that Cd uptake and translocation are genetically controlled warrants the selection of varieties that assimilate the least Cd and that translocate the least metal to the plant part to be used for human and animal consumption.     

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.     

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.     

Nutritional status of ‘Hass’ and ‘Fuerte’ avocado (Persea americana Mill.) plants subjected to high soil moisture

Abstract

In this study, the effect of increased soil moisture on the nutritional status of two key commercial avocado (Persea americana Μill.) cultivars, ‘Fuerte’ and ‘Hass’, was examined. The results revealed that prolonged exposure of plants to high soil water content conditions (waterlogging) reduced the total nutrient content (absolute quantity) of almost all of the nutrients in scion’s tissues (leaves and stems) of both cultivars. The decrease of nutrient content in the ‘Fuerte’ leaves was more prominent/severe compared to the ‘Hass’ leaves, which could be the outcome of the reported higher sensitivity of the cultivar to soil waterlogged conditions in previous studies. Interestingly, the inability of ‘Fuerte’ avocado plants to withstand high soil moisture conditions was not reflected in the relative concentrations of most nutrients, both in leaves and stems. Indeed, significantly higher concentrations of P, K, B, Fe, and Zn were found in the leaves of ‘Fuerte’ waterlogged plants than in well-watered ones. This fact reveals that under marginal/stressful conditions, like waterlogging, nutrient concentration in tissues does not reflect potential negative effects on total nutrient uptake of avocado plants, obviously due to concentrated nutrient phenomena primarily created by the stress-dependent growth inhibition. Therefore, total nutrient content is proposed as a more representative indicator for assessing plant response to waterlogged conditions.     

旱地甘蔗若干生理特性比较及其与抗旱性的关系

选用Ｆ１７２、Ｆ１３４、选蔗３号、桂糖１１号和粤糖５７／４２３为试验材料，于分蘖期、伸长初期、工艺成熟初期分别测定叶片细胞膜相对透性、ＮＡＤＰ－苹果酸酶活性、转化酶活性、光合色素含量以及叶片Ｎ，Ｋ，Ｃａ，Ｍｇ，Ｍｎ，Ｆｅ含量。结果表明：耐旱能力强的品种如Ｆ１７２，在旱地栽培时能保持较高的酶活性及光合色素含量，叶片细胞膜透性小，不耐旱品种粤糖５７／４２３则有相反的表现。选蔗３号叶片内Ｋ，Ｃａ，Ｍｇ等大量矿质元素含量较高，这可能是通过渗透调节作用影响其抗旱能力。     

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.     

IS CHLOROPHYLL FLUORESCENCE TECHNIQUE A USEFUL TOOL TO ASSESS MANGANESE DEFICIENCY AND TOXICITY STRESS IN OLIVE PLANTS?

A 130-day hydroponic experiment was carried out in a glasshouse to examine whether manganese (Mn) concentration in the nutrient solution affects the nutritional status of olive plants and to find out whether the chlorophyll fluorescence technique is suitable to assess Mn toxicity and/or deficiency stress in olive plants prior to the appearance of these two nutritional disorders. For this purpose, chlorophyll fluorescence parameters (F_v/F_m and F_v/F₀ ratios) were recorded every 40 days in the leaves of ‘Kothreiki’ and ‘FS-17’ olive cultivars, which were irrigated with Hoagland's nutrient solutions containing various Mn concentrations. In parallel the elongation of the main shoot of all experimental plants, as well as the concentrations of Mn, iron (Fe), zinc (Zn), boron (B), phosphorus (P), calcium (Ca), magnesium (Mg), and potassium (K) in their leaves were recorded. The following Mn treatments were applied: 0 μM Mn (to induce Mn deficiency), 40 μM Mn (to promote normal growth), and 640 μM Mn (to induce Mn toxicity). Our results indicated that not only the rate of shoot elongation but also the fluctuation with time of the leaf concentrations of all determined mineral elements (except for Mn) was not significantly affected by the Mn concentration in the nutrient solution, irrespectively of the cultivar. This was not observed with regard to the time variation of the F_v/F_m and F_v/F₀ ratios, where the values of these parameters were significantly reduced in the 640 μM Mn treatment at the 80th and 130th day of the experiment in both olive cultivars, compared to the relevant previous ones (those of the days 0 and 40th), something which did not happen in the other two Mn treatments (0 and 40 μM). However, in none of the two cultivars tested and in any of the three Mn treatments (0, 40 and 640μM) the F_v/F_m and F_v/F₀ ratios did not drop below the critical values of 0.8 and 4, respectively, even at the end of the experiment, where high Mn concentrations were found in the leaves of both cultivars treated with 640 μM Mn (616 μg g^?1 d.w. in ‘FS-17’ and 734 μg g^?1 d.w. in ‘Kothreiki’). Symptoms of Mn toxicity (curling and brown speckles) were observed in the top leaves of both cultivars, after the 90th day of the experiment. At the same time, the final leaf Mn concentrations (those of the 130th day of the experiment) in plants grown under 0 μM Mn were 23 μg g^?1 d.w. in ‘FS-17’ and 20 μg g^?1 d.w. in ‘Kothreiki’, i.e., a little above of the deficiency range (<20 μg g^?1 d.w.). At the 130th day, Mn concentration in nutrient solution, as well as Mn concentration in the leaves of both olive cultivars was negatively correlated with the leaf concentration of Fe and the values of the F_v/F_m and F_v/F₀ ratios, and positively with the concentrations of Zn and P in the leaves. Finally, the periodical measurement of the F_v/F_m and F_v/F₀ ratios was proved to be a non-reliable means to predict the appearance of the visible symptoms of Mn toxicity in olive leaves (although their values declined significantly at the 80th and 130th day of the experiment in both olive cultivars).     

硅对大葱矿质元素吸收、 分配特性及产量和品质的影响

【目的】大葱因含有机硫化合物等功效成分而具有重要的保健和药用价值,为此,前人曾就氮、 磷、 钾、 硫等矿质元素与大葱产量、 品质及风味物质的关系进行了一些研究。硅作为一种公认的有益元素,在提高作物产量、 改善品质等方面具有重要作用,本试验研究了硅对大葱矿质元素吸收、 分配特性和产量及品质的影响,以期为大葱高效施肥提供科学依据。【方法】本研究以‘天光’和‘章丘’两个不同类型大葱品种为试材,供试硅源均为Na2SiO3·9H2O,通过盆栽Hoagland营养液培养和大田土壤栽培相结合的方法,分别研究了营养液不同硅水平(SiO2 0、 0.6、 1.2、 1.8 mmol/L)和土壤不同施硅量(SiO2 0、 150、 300、 450 kg/hm2)对大葱生长、 产量、 品质及硅、 氮、 磷、 钾含量、 吸收量的影响。【结果】营养液硅水平在1.8 mmol/L范围内,‘天光’和‘章丘’两品种大葱株高、 假茎长、 假茎粗、 植株干重以及单株产量均随硅浓度升高呈先上升后下降的趋势,且均以1.2 mmol/L的处理表现最好,其单株产量分别较不施硅提高了19.4%和30.9%; 适量施硅还显著提高了大葱游离氨基酸、 可溶性糖、 丙酮酸等含量,表明施硅有利于改善大葱品质。随营养液硅水平的升高,两大葱品种各器官硅含量均显著增加,在1.8 mmol/L处理时达最高,而钾含量则与之相反,氮、 磷含量则呈先上升后下降的趋势,均以1.2 mmol/L处理含量较高; 由于施硅促进了大葱生长,所以大葱对硅及氮、 磷、 钾的吸收量则均随硅水平的升高呈增加趋势。大田施硅试验表明,‘天光’和‘章丘’两品种大葱均以施硅量(SiO2)300 kg/hm2时产量较高,分别比对照增产15.4%和25.6%。【结论】大葱增施硅可显著增加大葱对硅及氮、 磷、 钾的吸收量,促进植株生长,提高产量和品质,但同一硅水平的增产率以‘章丘’品种显著高于‘天光’,且二者随硅水平变化的幅度也不相同,表明不同大葱品种对硅的反应敏感性存在显著差异。本试验条件下,以营养液硅水平1.2 mmol/L、 土壤施硅300 kg/hm2时较有利于大葱的生长及产量和品质的提高。     

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’.     

Einfluß der Mineralstoffversorgung auf die Prädisposition von Phaseolus vulgaris gegen Colletotrichum lindemuthianum (Sacc. et Magn.) Br. et Cav. I. Wirkung verschiedener Nährstoffe und des Blattalters auf die Symptomausprägung

Influence of mineral nutrition on the predisposition of Phaseolus vulgaris against Colletrotrichum lindemuthianum (Sacc.et Magn.) Br.et Cav. I. Effects of different mineral nutrients and leaf-age on the disease severity 1. The N-concentration between 2–12 mMol N/I did hardly influence the disease, higher concentrations up to 52 mMol/I led to a severe disease increase. Potassium at concentrations of 5–10 mMol/I showed little effect on disease, higher concentrations up to 50 mMol also strongly increased the predisposition. 2. Calcium had a remarkable influence on symptom expression. Lower concentrations (1.15–0.25 mMol/I) increased the symptoms, higher concentrations up to 4.25 mMol/I reduced the disease, but only at a high disease level resulting from high N- or K-concentration. 3. The influences of Mg, P and Fe were of minor importance. 4. Usually, bean-leaves show resistance against C. lindermuthianum when the leaves are old. This is prevented by high N- and K-concentrations. 5. The change of predisposition related to the N- and K-concentration in the nutrient solution was confirmed with 3 additional bean varieties (‘Comtessa’ ‘Perry Marrow’, ‘Pizzaro’). No further increase of disease severity could be achieed with variety ‘Wavero’ which was generally very sensitive. 6. The monogenic resistance of incompatible combinations (‘Titan’/δ and ‘Titan’/λ) could not be changed with high N- or K-concentrations.     

Nutrient Distribution and Stem Length in Flowering Stems of Protea Plants

A study of nutrient distribution in the flowering stem of proteas was carried out in commercial protea plantations of each of the cultivars ‘Scarlett Ribbon’, ‘High Gold’, ‘Veldfire’, and ‘Sunrise’ of Leucospermum cordifolium, and of the species L. patersonii located in a subtropical zone (La Palma Island, Canarian Archipelago). Flowering stems were cut into different parts: flower bud, leaves from half proximal stem to the flower bud, leaves from half distal stem to the flower bud, half proximal stem to the flower bud, and half distal stem to the flower bud. Nutrient content of the different parts of the flowering stems of the cultivar and the species gave significant differences in some cases, depending on the nutrient and the cultivar. Occasional dissimilarities among the levels of nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) were determined in comparisons among half proximal stems and half distal stems, independent of the cultivar. The same trend was observed when nutrient contents of the leaves from the half distal and the half proximal stems were compared. Phosphorus exhibited the lowest concentrations of all macronutrients in the different organs. Flower buds presented the smallest levels of macro-and micronutrients, while the leaves of the half distal and half proximal stems showed the highest values. The influence of nutrients of leaves from the half proximal stems on the stems length varied among cultivars.     

FLORAL ANALYSIS AS A NEW APPROACH TO EVALUATE THE NUTRITIONAL STATUS OF OLIVE TREES

The main objective of this work was to evaluate if inflorescence analysis could be considered as an alternative to foliar diagnosis in determining the nutritional status of the olive orchards. Olive leaves from ‘Arbequina’ and ‘Chetoui’ cultivars in irrigated and rained systems were sampled within 8 phenological growth stages (dormant inflorescence bud, cluster development, petals whitening, fruit set, fruit development, stone hardening, fruit color break, and fruit ripening) from different sites of Tunisia during 2006 and 2007. Inflorescence samples were taken at petal whitening stage. Results showed that when ignoring the site of experimentation, some significant correlations were obtained between leaves and inflorescence during both years for ‘Arbequina’, at the stone hardening stage: standard date for leaf sampling, for nitrogen (N), phosphorus (P), copper (Cu), zinc (Zn), and manganese (Mn). Further work is required to assess the possibility of using inflorescence analysis to diagnose the nutritional status of olive trees.     

EFFECT OF CITRUS ROOTSTOCKS ON LEAF MINERAL COMPOSITION OF ‘OKITSU’, ‘CLAUSELLINA’, AND ‘SILVERHILL’ MANDARIN CULTIVARS

Citrus performance is strongly related with rootstock. This study was conducted to investigate leaf nutrient contents of ‘Okitsu’, ‘Clausellina’ and ‘Silverhill’ mandarin cultivars budded onto sour orange, ‘Carrizo’ and ‘Troyer’ citrange rootstocks in Dörtyol, Turkey in 2004 and 2005. The maximum nitrogen (N), potassium (K), and copper (Cu) contents were determined for ‘Clausellina’; phosphorus (P) for ‘Okitsu’; and sodium (Na) for ‘Silverhill’. Calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn) uptake were similar for the mandarin cultivars. ‘Carrizo’ citrange at N, K, Mg, Mn, and Cu uptake; ‘Troyer’ citrange at N, P, K, and Fe uptake; and common sour orange at Ca, Zn, and Na uptake was superior on the other rootstocks. It was observed that ‘Carrizo’ and ‘Troyer’ citrange rootstocks had advantages over sour orange in nutrient uptake. Thus, growth performance, yield, and quality parameters considered, ‘Carrizo’ and/or ‘Troyer’ citranges could be suggested as rootstocks for the studied mandarin cultivars under similar ecological conditions.     

Dry Matter and Nutrient Partitioning of Selected Pineapple Cultivars Grown on Mineral and Tropical Peat Soils

The pineapple cultivars ‘Moris’ (Queen cultivar), ‘N‐36’ (‘Sarawak’ × ‘Gandul’ hybrid), ‘Gandul’ (Singapore Spanish cultivars), and ‘Josapine’ (‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid) are mostly grown on peat soils in Malaysia, whereas ‘Sarawak’ (‘Smooth Cayenne’ cultivar) is more commonly grown on mineral soils. To obtain good yields of fruit of high quality, it is important to understand the differences in nutrient requirements for these cultivars in the different soils in which they are grown. Therefore, the objectives of the study were to determine the biomass and nutrient partitioning of the different pineapple cultivars and to determine the plant variables affecting fruit yield and quality. Plants of each of the pineapple cultivars were randomly sampled from different locations of the major pineapple‐growing areas in Malaysia. Only plants having A‐grade fruit of marketable quality at harvest were selected. The cultivars and respective field sites were as follows: ‘Sarawak,’ Bukit Tandak farm, Kelantan (5° 55.274′ N, 102° 00.608′ E); ‘Moris,’ ‘N‐36,’ and ‘Gandul,’ Peninsula Pineapple Plantations, Simpang Renggam, Johor (1° 49.909′ N, 103° 14.053′ E); and ‘Josapine,’ Goh Swee Eng Pineapple Farm, Simpang Renggam, Johor (1° 48.441′ N, 103° 11.935′ E). Plants were partitioned into roots, stem, leaves, peduncle, fruit, and crown, and fresh and dry weights were recorded. Total biomasses for the different cultivars were 733.46 ± 22.83 g for ‘Gandul,’ 842.34 ± 43.26 g for ‘N‐36,’ 927.38 ± 53.10 g for ‘Moris,’ 434.77 ± 16.82 g for ‘Josapine,’ and 2446.94 ± 156.00 g for ‘Sarawak.’ Leaves accounted for the greatest proportion of dry matter (48.5%), followed by fruit (22.9%) and stem (21.6%), and a smaller proportion (1.2–2.5%) was roots, peduncle, and crown. The proportions of the dry‐matter accumulation in leaves and stem for the cultivars were 53.5 ± 0.7 and 16.7 ± 0.9% for ‘Gandul’; 45.1 ± 0.5 and 17.7 ± 0.7% for ‘N‐36’; 51.9 ± 1.6 and 16.8 ± 0.6% for ‘Moris’; 56.5 ± 1.0 and 12.0 ± 0.9% for ‘Josapine’; and 54.2 ± 5.1 and 27.7 ± 4.4% for ‘Sarawak.’ The proportion of the macro‐ and micronutrients in pineapple parts differed widely between cultivars. Potassium (K) showed the greatest proportion (7.96 ± 0.6 to 29.73 ± 1.17%) in leaves and (4.46 ± 0.70 to 9.35 ± 0.28%) in fruit followed by nitrogen (N) and phosphorus (P) with lower proportions. Most pineapple cultivars grown showed variation in nutrient‐use efficiency (NUE) with respect to the elements measured with values of <1.0 g dry matter g^?1 nutrient. The NUE values of >1.0 g dry matter g^?1 nutrient were observed for magnesium (Mg) in ‘Gandul’ and ‘N‐36’ and for calcium (Ca) and copper (Cu) in ‘N‐36.’ Total nutrient accumulation in the plant components differed approximately according to their cultivar origins (‘Smooth Cayenne,’ ‘Queen,’ ‘Singapore Spanish’). It is interesting that the results for the ‘Singapore Spanish’ × ‘Smooth Cayenne’ hybrid Josapine were more similar to the ‘Singapore Spanish’ cultivars than being between the parents. Partitioning of biomass and nutrients in pineapple provides a means to categorize them and makes it possible to use a cultivar‐based fertilization program.     

Effects of Seasonal Nitrate Flush on Nitrogen Metabolism and Soluble Fractions Accumulation in Two Rice Varieties

ABSTRACT

Two rice varieties, ‘Piaui’ (a landrace) and ‘IAC-47’ (an improved variety), were grown in nutrient solution containing 20 mg nitrate (NO₃ ^?)-nitrogen (N) L^{? 1} up to 32 days after germination (DAG). After this, a group of plants received 200 mg NO₃ ^?NL^{? 1}, while the other was kept at 20 mg NO₃ ^?NL^{? 1} up to 42 DAG. From 42 until 56 DAG, all plants received 5 mg NO₃ ^?NL^{? 1}. Plants were collected at 42 and 56 DAG, soluble fractions, nitrate reductase (NR) and GS enzymatic activities were determined. The nutritional history of the plants affected significantly the uptake and use of nitrogen (N), and should be taken into consideration in the studies of N-use efficiency. The variety ‘Piaui’ was more efficient than ‘IAC-47’ in N-uptake use, accumulating more NO₃ ^? in its tissues at the initial phases of its cycle for subsequent utilization.