Influence of nitrogen and potassium on micronutrient content of fifteen cultivars of bermudagrass

Abstract

There is limited information concerning the micronutrient composition of different turfgrass species and cultivars. Bermudagrass [Cynodon dactylon (L.) Pers.] is an important turfgrass utilized throughout the Southeastern and Southwestern states and the transition zone of the United States. A study was conducted to determine the effects of different rates of nitrogen (N) and potassium (K) on the micronutrient content of fifteen bermudagrass cultivars. The cultivars utilized were: ‘Ormond’, ‘Texturf 10’, ‘Tiflawn’, ‘Tufcote’, and ‘U‐3’ [Cynodon dactylon (L.) Pers.]; ‘Everglades’, ‘Midiron’, ‘Midway’, ‘Pee Dee’, ‘Santa Ana’, ‘Tifdwarf, ‘Tifgreen’, ‘Tifway’, and ‘Tifway II’ [Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Burtt‐Davey]; and ‘Sunturf [Cynodon magennisii Hurcombe]. The study was a 2x2 factorial with the factors being two levels each of N and K imposed on the fifteen cultivars. It was a completely randomized design with three replications. The N and K rates were 227 g N and 227 g K 93 m^‐2 month^‐1 (low rates) and 454 g N and 454 g K 93 m^‐2 month^‐1 (high rates) that resulted in four N:K treatment combinations as follows: 1) high N:high K; 2) high N:low K; 3) low N:high K; and 4) low N:low K. Plant tissue samples were collected in late August and analyzed for boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn). There were differences for the Cu, Fe, Mn, and Zn concentrations for several cultivare under certain treatment combinations. Zinc concentrations exceeded the sufficiency range in all but one instance, while there were several cases in which Fe and Mn concentrations were above the sufficiency range. The levels of B and Cu were within the sufficiency range and there were no differences for B.     

Salt influence on germination and seedling survival of six cool season turfgrass species

Abstract

‘Merion’ Kentucky bluegrass (Poa pratensis L.), ‘Pennfine’ perennial ryegrass (Lolium perenne L.), ‘Seaside’ creeping bent‐grass (Agrostis palustris Huds.), ‘Dawson’ slender creeping red fescue (Festuca rubra trichophylla (L.) Gaud.), ‘Fults’ weeping alkaligrass (Puccinellia distans (L.) Parl.), and ‘common’ Lemmon alkaligrass (Puccinellia lemmoni (Vasey) Scribn.) were evaluated for germination and seedling survival in the greenhouse and laboratory under saline conditions. Overall results indicated that weeping and Lemmon alkaligrass were superior performers under saline and/or sodic conditions. Among the remaining four species, none appeared clearly superior in overall performance.     

Ozone tolerances of soybean cultivars and near‐isogenic lines in a fumigation chamber

Ozone (O₃) toxicity is a potential yield‐limiting factor for soybean (Glycine max L. Merr.) in the United States and worldwide. The most economical solution to the problem is to use O₃‐tolerant cultivars. Thirty‐four cultivars and 87 near‐isogenic lines (NILS) of soybean were screened for O₃ tolerance in a fumigation chamber (250 ppb for three hrs). Most tolerant cultivars tested were ‘Cloud’, ‘T‐276’, ‘T263’, and ‘Kindu’. Moderately tolerant cultivars included ‘Davis’, ‘T‐210’, and ‘Elton’. Most sensitive cultivars were ‘Corsoy 79’, ‘Noir’, and ‘Midwest’. The original ‘Clark’ cultivar was not tested, but ‘Clark 63’ tended to be more tolerant than ‘Harosoy’. The aluminum (Al)‐tolerant ‘Perry’ cultivar also tended toward greater O₃ tolerance than the Al‐sensitive ‘Chief’, as observed earlier. Our rankings of ‘Hark’ as moderately sensitive and ‘Davis’ as moderately tolerant are also in agreement with earlier reports. Among NILS, the order of O₃ tolerance was generally Williams>Clark>Harosoy, but differences were also observed within these parental groups. For example, L68–560 was more tolerant than some other NILS of ‘Harosoy’. ‘L76–1988’ appeared more tolerant to O₃ than other NILS of ‘Williams’, but all ‘Williams’ NILS were more tolerant than most NILS of ‘Harosoy’ and ‘Clark’. Ozone‐tolerant and ‐sensitive soybean cultivars or NILS identified in our study may be useful tools in studies on mechanisms of 03 tolerance and differential 03 tolerances in plants and in the development of ameliorative measures.     

Late blight and virus host-plant resistances,crossing ability and glycoalkaloids in Nordic potato germplasm*

Old potato cultivars from the Nordic Genetic Resource Center (NordGen) and advanced breeding clones from the Swedish University of Agricultural Sciences (SLU) were evaluated for susceptibility to Potato Virus Y (PVY) and Potato Leafroll Virus (PLRV), foliar and tuber resistance to late blight – caused by Phytophthora infestans – as well as for glycoalkaloid content and crossing ability. Enzyme-Linked Immunosorbant Assay (ELISA) tests were used for PVY and PLRV screening during two years that were characterized by intensive virus incidence and severity in the field, while foliar and tuber resistances to late blight were assessed under artificial inoculation with an aggressive Swedish isolate of P. infestans. Hybrid seeds were obtained by crossing cultivars such as ‘Kiva’, ‘Sarpo Mira’, ‘Rosamunda’ and ‘Superb’ with SLU advanced breeding clones and a selected clone of Solanum tuberosum Group Andigena. Some cultivars (‘Hårek’, ‘Sarpo Mira’) and breeding clones (04-2662, 04-2085) with late blight resistance did not show virus infection. The α-solanin and α-chaconin contents of some of the old Nordic potato cultivars and breeding clones were similar to the known Dutch table cultivar ‘Bintje’ after 3 years of testing. This research allows identification of promising Nordic potato cultivars and SLU breeding clones for further use in developing germplasm aiming at organic and conventional farming systems.     

A greenhouse technique for screening Trifolium seedlings for iron‐deficiency chlorosis 1

Susceptible Trifolium plants often exhibit symptoms of iron (Fe)‐deficiency chlorosis when grown on high pH, calcareous soils. A greenhouse method was developed to screen seedlings for Fe‐deficiency chlorosis. ‘Yuchi’ arrowleaf (T. vesiculosum Savi.) and ‘Dixie’ crimson (I. incarnatum L.) clover seedlings were grown in “Super Cell”; Cone‐tainers in six calcareous Texas soils differing in Fe and selected other chemical characteristics. At the fourth trifoliolate leaf stage, chlorosis was induced by saturating the soil for a minimum of 2 weeks. The soils differed in their capacity to induce chlorosis in both clovers. Yuchi was more susceptible than Dixie, showing a higher percentage of chlorosis in five of the six soils. The results indicate that this screening method would be a useful tool for studying Fe‐deficiency chlorosis in Trifolium spp.     

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.     

Influence of ca concentration on growth,tissue concentration,and nutrient uptake of in vitro propagated plums and lovell seedlings

Seedlings of ‘Lovell’ peach [Prunus persica (L.) Batsch], and in vitro propagated plums, ‘St. Julien A GF 655–2’ [Prunus institia (L.) Bullace] (655–2), ‘Damas GF 1869’ [Prunus domestica (L.)] (D1869), and ‘Clark Hill Red Leaf’ [Prunus saliciana (Lindl) x Prunus cerasifera (EHRH)] (CH redleaf) were grown in the greenhouse 45 or 51 days in nutrient solutions containing 2, 6, 22, 200, and 400 μM Ca. Terminal length, number of laterals, trunk cross‐sectional area, and root volume were increased by the 22 μM Ca treatments at harvest 1. The CH redleaf and 655–2 plums had the largest increase in growth for harvest 1, but the ‘Lovell’ peach seedlings and D1869 plum had the largest increase in growth for harvest 2. There were no leaf symptoms of Ca deficiency when the leaf Ca concentration in the tissue exceeded 2500 μg/g (dry wt.) Calcium concentration was increased from 1406 to 4109 μg/g (dry wt.) in the stems, and from 540 to 2633 μg/g (dry wt) in the roots by Ca treatments of 400 μM after 45 days of growth. Calcium uptake rate for ‘Lovell’ seedlings was greater than were rates for CH redleaf and 655–2 plums at all solution concentrations during the first 45 days of growth. The Ca uptake rate for D1869 plum was greater than the rate for ‘Lovell’ seedlings during the second growth period. An interaction between Ca concentration and plant species occurred for P, K, and Mg uptake rates at both harvest dates. The in vitro propagated D1869 plum was equal to the ‘Lovell’ seedlings in growth, tissue Ca concentration, and Ca uptake rates.     

Relationship of Soluble Salts Content in MSW Compost Media and Rooting of Evergreen Cuttings

Municipal solid waste (MSW) compost media with various levels of soluble salts were used for rooting stem cuttings of nine evergreen landscape shrubs: Buxus sempervirens L. ‘Green Gem’; Juniperus chinensis L. ‘Hetzii; J. chinensis ‘Mint Julep’; J. chinensis ‘Pfitzeriana Aurea’; J. horizontalis Moench ‘Bar Harbor’; J. horizontalis ‘Blue Chip’; J. sabina L. ‘Blue Danube’; Taxus x media Rehd. ‘Densiformis’; and Thuja occidentalis L. Rooting occurred during the winter in greenhouse compartments supplied with bottom-heated benches filled with 100% sphagnum peat or 100% perlite, or peat or perlite mixed with 15, 30, 45, 60 or 75% by volume of MSW compost. The electrical conductivity (salt) levels were similar in MSW compost with peat or with perlite (range, 0.05-0.60 dS·m^?1 with 0-75% compost) and positively correlated with levels of MSW (r = 0.88, P≤0.001). With few exceptions, cuttings rooted similarly in MSW with peat or perlite. Depending on taxa, increasing salt levels had various degrees of diminutive, neutral, and enhancing effect on rooting response, expressed in terms of percent rooting, root number per cutting, and root length (longest root per cutting). Four taxa (J. horizontalis ‘Bar Harbor’ and ‘Blue Chip’, J. sabina ‘Blue Danube’, and T. occidentalis) were tolerant of the salt levels tested (positively influenced or unaffected). The other five taxa were intolerant (adversely affected).     

Yield of iron‐sprayed and non‐sprayed strawberry cultivars grown on high ph calcareous soil

Abstract

Iron (Fe) deficiency chlorosis (FeDC) results in extensive reduction in yield of strawberry (Fragaria x ananassa Duch.) grown on high pH calcareous soils. Three cultivars differing in response to FeDC were grown on a high pH (8.2) calcareous soil (25.4% calcium carbonate equivalent in surface 20 cm) in the field (Choueifat, coastal area of Lebanon) to determine the effects of FeDC on fruit yield of cultivars sprayed with FeEDDHA [ferric ethylene‐diiminobis (2‐hydroxyphenyl) acetate]. The unsprayed plots were used as a control. No significant interaction (P<0.05) between cultivars x FeEDDHA spray treatment, and no significant differences (P<0.05) between one and two FeEDDHA spray(s)/week treatment was noted for visual FeDC, fruit number, and fruit yield. Sprayed cultivars once a week produced higher yields than unsprayed ones; overall increases were 33% (13% for ‘Motto’, 30% for ‘Chandler’, and 56% for ‘Douglas'). Even though only slight FeDC was noted on the ‘Motto’ cultivar receiving no Fe EDDHA spray, fruit yields were increased when sprayed with FeEDDHA. However, significant increases in yield for ‘Chandler’ and ‘Douglas’ cultivars with severe FeDC ratings were rioted when sprayed with FeEDDHA.     

Biomass production and water use efficiency of barley and wheat plants with different irrigation intervals at various water levels

Biomass production in terms of dry‐matter yield of both straw and grains of barley (Hordeum vulgare L., cv. ‘Walfajr') and wheat (Triticum aestivum L., cv. ‘Karaj I') plants subjected to water stress were studied at the College of Agriculture, University of Tehran Experimental farm located in the city of Karaj, Iran. The treatments consisted of two irrigation intervals, 7 and 14 days. Six water levels, 100, 80, 60, 40, 20, and 0% of the crops’ total water requirements were used at each irrigation interval. The experimental units consisted of 2.5m × 2.5m plots replicated three times for each treatment. A 1m x 1m sub‐plot at the center of each 2.5m X 2.5m plot was selected and the plants were harvested to prevent border effects. After each harvest, the straw and the grains were separated and weighed.

Total dry‐matter yield of straw and grains significantly decreased by decreasing applied water levels (especially, at the lower water levels, 40, 20, and 0%) and increasing irrigation intervals for both plants. Water use efficiency (WUE) was higher at the higher applied water levels for the straw than for the grains for barley, however, the trend was reverse for wheat plants. The WUE decreased for straw by deceasing applied water in both barley and wheat plants.     

Field evaluation of phenology and success of hardy,micro-propagated old shrub roses in northern Finland

Abstract

Five old shrub rose taxa were studied in field experiments in northern Finland during the years 1993–1999. The plant material was micro-propagated from woody plants selected for their ornamental value and hardiness for northern areas of Finland. The observations in the experiments were based on phenological monitoring and survey of plant success. The results revealed significant differences in the success of the different rose genotypes, and the most valuable genotypes were identified. Micropropagation was successfully used as a propagation method and these in vitro propagated roses grew naturally under harsh field conditions. The Rosa ‘Tornedal’ origins, R. ‘Poppius’ and R. ‘Sipi’ were ranked the most suitable cultivars for northern landscaping. Overall, all of the studied roses succeeded fairly well.     

Remote sensing of sugarbeet canopies for improved nitrogen fertilizer recommendations for a subsequent wheat crop

Abstract

Return to soil of high N, green sugarbeet (Beta vulgaris L.) tops, but not the return of low N, yellow to yellow‐green tops, reduces the magnitude of N‐fertilizer responses for the following crop. Twelve N fertilizer trials with spring wheat (Triticum aestivum L.) were established at sites with late‐season ‘green’ (8 sites) or ‘yellow’ (4 sites) sugarbeet canopies the previous year. Late‐season, aerial color photographs of sugarbeet fields and global positioning system (GPS) technology were used to locate the experimental sites. Based on the soil NO₃‐N test customarily used in the Northern Grain Plains, N fertilizer responses were expected at 11 of the 12 sites. However, no significant grain‐yield responses were obtained at the eight antecedent ‘green’ sugarbeet sites. Expected yield and grain‐N responses were obtained at the four antecedent ‘yellow’ sites. In contrast to the usual soil NO₃‐test, remote sensing of the previous sugarbeet crop resulted in successful prediction of N‐fertilizer responses at all 12 experimental sites. Application of N fertilizer at the ‘green’ canopy sites increased the likelihood that excess soil NO₃‐N would be present after the wheat harvest. A precision farming technique, involving remote sensing of late‐season sugarbeet canopies, use of GPS technology, and use of variable rate N‐fertilizer application is recommended for a wheat crop following sugarbeet.     

Relationship of fertilizers on soil ph and fruit disorders of apples and pears

Abstract

In nutrition experiments of fruit‐growing areas of central Washington state, ‘Delicious’ and ‘Golden Delicious’ apple (Malus domestica) orchards and ‘d'Anjou’ pear (Pyrus communis L.) orchards with the lowest soil pH values had a high incidence of fruit disorders and the lowest concentration of leaf calcium (Ca). In contrast, orchards with the highest soil pH values had the highest concentration of soil Ca (meq 100 g^‐1) and the lowest incidence offrait disorders (bitter pit for apples and alfalfa greening, black end and cork spot for pears). Apple orchards with the highest soil pH values also had ‘Delicious’ and ‘Golden Delicious’ apples containing the highest concentration of Ca, but Ca concentrations in ‘d'Anjou’ pears were not significantly different among the different soil pH groups.     

Interseeded legumes with loblolly pine. II. Effect of phosphorus and legume variety on the growth of pine seedlings

A field study was initiated to quantify growth attributes of loblolly pine (Pinus taeda L.) when intercropped with warm‐season annual legumes. In addition to main treatments, subplots of phosphorus (P) and a cool‐season annual legume were also evaluated as factors contributing to growth of pine trees. After 3 years, pine seedlings grown with ‘Iron and Clay’ cowpea [Vigna unguiculata (L.) Walp.] had grown to a height of 315 cm and had a diameter of 63 mm which was a substantial increase when compared to plants receiving other treatments. Phosphorus application had no effect (P>.10) on pine growth parameters. The addition of ‘Tibbee’ crimson clover (Trifolium incarnatum L.) affected height (P<.10) of pine trees grown with ‘Comanche’ partridge pea (Cassia fasciculata Michx), and pine trees grown alone (control). Regression analyses indicated no correlation between rate of growth in height of pine trees and warm‐season legumes over a three‐year period. Growth rate in diameter during this period, however, was greatest for pine trees growing with cowpeas. Pine seedlings grown as a control or with alyceclover had similar diameter growth rate, but then grew slower than pines with cowpeas, and faster than pines grown with partridge peas.     

Modelluntersuchungen zur mineralisierung der biomasse von Miscanthus x giganteus (Mineralisierung von Miscanthusbiomasse)

Im Rahmen eines fach übergreifenden Forschungsprogramms wurde die Mineralisierung verschiedener Bestandteile der Biomasse von Miscanthus x giganteus modellhaft untersucht. Daten zur Nährstofffreisetzung und zur Reproduktionswirksamkeit der organischen Rückstände dieser Dauerkultur waren das Ziel der Experimente.

Bei spezifischen Abbauraten verlief die Umsetzung der Miscanthusbestandteile wie die Umsetzung von Stroh. Nur die Wurzeln wurden in deutlich geringerem Umfang mineralisiert. Im Verhältnis zu Stalldung schwankte die Humusreproduktionswirkung der organischen Rückstände von Miscanthus x giganteus zwischen 0,6 (Rhizome), 0,6–0,9 (oberirdische Rückstände) und 1,0 (Wurzeln). Dies führt dazu, daß in etablierten Beständen von Miscanthus x giganteus jährlich zwischen 5 und 9 t/ha organische Substanz anfallen, die der Humusreproduktion des Bodens dienen. Der Prozeß der Mineralisierung führte zu einer teilspezifischen Netto‐N‐Immobilisierung. Ein engeres C/N‐Verhältnis in der Miscanthusbiomasse, keine Einmischung in den Boden und ein nur grobes Zerkleinern bewirkten in der Regel eine stärke N‐Freisetzung.

Die Ergebnisse berechtigen zu der Aussage, daß Miscanthus x giganteus als humusmehrende Pflanzenart zu bezeichnen ist. Die Mineralisierungsbedingungen auf dem Feld (keine Zerkleinerung, keine Einarbeitung der organischen Substanz) müssen bei der Bewertung der Ergebnisse berücksichtigt werden.     

Nitrogen transfer from warm‐season annual legumes to pearl millet

A glasshouse study was conducted to determine and quantify direct transfer of nitrogen (N) between 3 selected warm‐season annual legumes and a warm‐season annual grass during the growing season, ‘Tifleaf’ pearl millet [Pennisetum americanum (L.) Leeke] was grown in pots as a monoculture with and without N applied as inorganic fertilizer, or with either ‘Iron and Clay’ cowpeas [Vigna unguiculata (L.) Walp], common alyceclover [Alysicarpus vaginalis (L.) DC.], or ‘Comanche’ partridge pea (Cassia fasciculata Michx.). Sixty‐three percent of the N contained in pearl millet grown with alyceclover was derived directly from alyceclover as determined by the ¹⁵N dilution technique. Partridge peas and cowpeas transferred 34% and 32%, respectively, of the N contained in companion pearl millet plants. Pearl millet grown with partridge peas produced dry matter yields similar to pearl millet that received the equivalent of 112 kg N/ha. Pearl millet grown with legumes contained lower levels of neutral detergent fiber than did pearl millet that received inorganic fertilizer. Nitrogen content of pearl millet grown with legumes was not as great as pearl millet that received N‐fertilizer.     

Influence of rootstocks on ‘Orlando’ tangelo leaf elemental concentration

Abstract

The influence of 10 rootstocks on leaf elemental concentrations and their relationship with yield, tree growth, leaf fresh weight and dry matter of ‘Orlando’ tangelo (C. parodisi Macf. x C. reticulata Blanco) was studied under the arid climate of southwestern Arizona. ‘Orlando’ tangelo trees on Carrizo citrange [(C sinensis (L.) Osbeck x Poncirus trifoliata (L.) Raf.], Yuma citrange (P. trifoliata x C. sinensis), Taiwanica (C. taiwanica) and Volkamer lemon (C. limon Burm f.) had larger canopy and higher yield than the trees on Savage citrange (P. trifoliata x C. sinensis), Ichang pummelo (C. ichangensis hyb.) and Palestine sweet lime (C. limettoides Tan.). Leaves of trees on Carrizo citrange were heavier but those on Savage citrange had higher percent dry matter than those on other rootstocks. Trees on macrophylla (Alemow) (C macrophylla Wester) had significantly higher leaf N and Mn while those on Carrizo, Yuma and Savage citranges had lower leaf N than the trees on other rootstocks. Trees on Volkamer lemon, rough lemon (C. jambhiri Lush), macrophylla and Palestine sweet lime had low leaf K but high leaf Mg. ‘Orlando’ trees on Carrizo citrange had the highest leaf Mg and Cu but the lowest leaf Mn. Considering mineral (elemental) uptake efficiency, tree growth and/or yield, Carrizo citrange, Volkamer lemon, Yuma citrange, rough lemon and Taiwanica are desirable for ‘Orlando’ tangelo under the arid conditions and sandy soils of the southwest United States. Macrophylla could only be used for a short term planting, while Savage citrange, Batangas mandarin (C. reticulata Blanco), Ichang pummelo and Palestine sweet lime are not recommended for planting under the arid conditions similar to those of this experiment.     

Nutrient Removal,Fertilization Needs and Yields of Protea Plants Cultivated in Subtropical Conditions

A study of nutrient removal 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 region (La Palma, Canarian Archipelago).

Flowering stems of optimal commercial quality were taken from each of the mentioned cultivars and species, once a year (2003 and 2004) at harvest time (January to April), and the different organs were analyzed separately. Flowering stems of the cultivars ‘High Gold’ and ‘Veldfire’ presented the highest contents of most studied nutrients, whereas the opposite was observed in ‘Scarlett Ribbon’ and L. patersonii. Mean yields of flowering stems varied very much among cultivars, and the highest ones were those of ‘High Gold’ and ‘Scarlett Ribbon’. The cultivar ‘High Gold’ removed the highest quantities of studied nutrients, and the contrary was observed in L. patersonii for most of them.

Suitable rates of nitrogen (N): phosphorus (P): potassium (K) fertilizers for nutrient restitution purposes were 1:0.08:0.40 for ‘Scarlett Ribbon,’ 1:0.08:0.66 for ‘High Gold,’ 1:0.08:0.38 for ‘Veldfire,’ 1:0.09:0.75 for L. patersonii;and 1:0.18:1.11 for ‘Sunrise’.     

Effect of B,Mn and Zn on nodulation and N2‐fixation in southernpeas

Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N₂‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N₂‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N₂‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N₂‐fixation to seed yield.     

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.