. Leaf mineral nutrients. Leaf samples (20 fully developed leaves from new growth) from developed plants were dried at 70 °C for 2 d and analyzed for mineral nutrient concentration at the Univ. of Georgia Agricultural & Environmental Services Laboratories
The influence of six rootstock on growth, yield, fruit quality, and leaf mineral nutrient concentration of `Fairchild' mandarin [`Clementine' mandarin (Citrus reticulata Blanco) × `Orlando' tangelo (C. paradisi Macf. × C. reticulata)] is reported for the arid climate of southwestern Arizona. Trees on macrophylla (Alemow) (C. macrophylla Wester) were precocious and produced high yield 4 years after planting. Six-year cumulative yields of trees on Volkamer lemon (C. limon Burro f.), Carrizo citrange [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.], Taiwanica (C. taiwanica Tan. & shin.), and rough lemon (C. jambhiri Lush.) were similar and higher than those of trees on macrophylla and Batangas mandarin (C. reticulata). `Fairchild' mandarin tree canopies were large with Volkamer lemon and Taiwanica; intermediate with Carrizo citrange, rough lemon, and Batangas mandarin; and small with macrophylla rootstock. Fruit from trees on Carrizo citrange had the highest soluble solids concentration (SSC), while those on Volkamer lemon and rough lemon had the lowest SSC and total acids. `Fairchild' trees on macrophylla had higher levels of leaf N, Mn, and Fe but lower Ca, while trees on Batangas mandarin and Carrizo citrange had higher leaf K than those on the other rootstock. Trees on Volkamer lemon had higher leaf Zn than those on Carrizo citrange, Taiwanica, rough lemon, and Batangas mandarin rootstock. Considering yield, growth, fruit quality, and/or leaf nutrient concentration, Volkamer lemon, Carrizo citrange, Taiwanica, and rough lemon are suitable for `Fairchild' mandarin in the arid regions of southwestern Arizona. Trees on macrophylla could be advantageous for short-term planting, but would not be satisfactory for long-term planting because of gradual decline in growth and yields. Batangas mandarin is not recommended for `Fairchild' mandarin due to poor production.
To observe changes in the nutritional status of corollas during development and senescence, Petunia ×hybrida cv. Mitchell corollas were analyzed for macronutrient and micronutrient content, dry weight, fresh weight, and ethylene production. Carbon content decreased at slightly lower rates than dry weight during corolla development between anthesis and senescence, while fresh weight and ethylene production followed patterns expected of climacteric flowers. Nitrogen, phosphorus, and potassium content declined during development. Both phosphorus and potassium content gradually declined throughout development with overall losses of about 75% and 40%, respectively. Nitrogen content declined 50% during development but losses occurred only during the final stages of senescence. No significant changes were observed in sulfur, calcium, magnesium, and micronutrient content of the corollas during development. Most elements were present in much lower concentrations in corollas than in leaves. The concentrations of calcium, magnesium, and manganese were about 1-, 5-, and 15-fold lower in corollas than in leaves, respectively. Results indicate that remobilization of selected macronutrients from corollas occurred before and during senescence. Taken together with the presence of low concentrations of macronutrients, my data support the contention that petunia corollas are nutritionally in expensive and therefore easily disposable organs.
Containerized seedlings of eastern redcedar (Juniperus virginiana L.) were fertilized weekly for 175 days with a solution containing 50 ppm P, 150 ppm K, and either 0, 5, 10, 20, 40, 80, 160, 320, or 640 ppm N. Plant height, stem diameter, and shoot and root dry weights increased asymptotically with applied N; 640 ppm N diminished response. Growth after 175 (height, stem diameter) and 180 (shoot and root dry weights) days was optimal (90% of maximum) at N concentrations of 115, 155, 230, and 105 ppm, respectively, 1.5% foliar N optimized height growth. Foliar concentrations of N, P, and K increased in treated plants over the duration of the experiment, while Ca, Mg, and Mn decreased or remained constant. Starch concentration of fertilized plants decreased sharply after initiation of the experiment, but controls showed little change during the first 120 days. Sucrose concentration remained constant over the summer but increased sharply in late fall. At 180 days, foliar concentrations of starch, sucrose, hexose, N, P, K, and B increased asymptotically with applied N; concentrations of Ca, Mg, and Mn decreased.
Floricane-fruiting blackberry (Rubus L. subgenus Rubus, Watson) cultivars, ‘Marion’, ‘Black Diamond’, ‘Onyx’, ‘Columbia Star’ (early-season trailing types), ‘Ouachita’ (erect, midseason), and ‘Triple Crown’ and ‘Chester Thornless’ (semierect, late season) were studied for 2 years to determine whether these cultivars and types of blackberry should be sampled at a certain stage of development or time of season to best evaluate plant nutrient status. Leaf nutrient standards are based on primocane leaves in most countries, but there is interest in using floricane leaves. Primocane leaves were sampled every 2 weeks from late May through early October, whereas leaves on fruiting laterals (floricane) were sampled every 2 weeks from early May through fruit harvest. Leaves were analyzed to determine the concentration of macronutrients and micronutrients. The pattern of change in primocane leaf nutrient concentration varied between the trailing and the later-fruiting erect and semierect types, particularly for P, K, Ca, Mg, B, and Mn, where leaf levels were higher in the late season for the erect and semierect cultivars (except for P and K which were lower). Nutrient concentrations in floricane leaves decreased during growth and development of the lateral and fruiting season for N, P, K, and S, but increased for most other nutrients in all blackberry types. Floricane leaf N and K declined most rapidly during the fruit development period in all cultivars. Sampling of floricane leaves is not recommended, particularly for trailing types, as there are no sufficiency standards. In primocane leaves, the nutrients that did not show significant changes in concentration during the currently recommended sampling period of late July to early August were N, Mg, K, Ca, S, B, Mn, and Zn, but only in 2014. Leaf P, Fe, and Al were stable during this period in both years. In contrast, when sampling in mid to late August, leaf N, Mg, Fe, Mn, and Al were stable in both years and leaf K, Ca, S, B, Cu, and Zn were stable in one of the 2 years. We thus propose changing the recommended sampling time to mid to late August for these diverse blackberry cultivars. The current sufficiency standards for primocanes did not encompass the blackberry types and cultivars studied here, suggesting the standards may need to be revised for this region.
Pickling cucumbers (Cucumis sativus L.) were grown at high plant population (250,000 plants/ha) for once-over harvest. Nitrogen was applied preplant, 0 to 268 kg/ha, and sidedress, 0 to 112 kg/ha, from 2 N sources, NH4NO3 and urea. The effects of N fertilization practices on mineral nutrient composition of the tissue was studied. The concentration of NO3-N in leaf blade and petiole tissue rapidly decreased during the last 2 to 3 weeks before harvest (fruit sizing period). Preplant and sidedress N fertilizer applications led to increased tissue concentration of NO3-N and total N. Petiole tissue concentration less than 0.8% NO3-N or greater than 1.5% at harvest usually reflected reduced yields. Optimum yields generally occurred when blades contained 4 to 5% total N. The source of N fertilizer used had little influence on tissue concentration of NO3-N and total N. Nitrogen fertilization practices had a direct influence on the mineral nutrient composition of the leaf tissue at harvest. Tissue concentration of K, Ca, Mg, Fe and Mn were higher in tissue that received preplant fertilizer N rates from 67 to 201 kg/ha compared to plants that received no preplant N, while the Na concn was reduced. Sidedressing N fertilizer had little influence on cation and anion accumulation in the tissue.
foliar K (2.9%, 2.1%) concentrations for Hibiscus coccineus Walt. and Rudbeckia fulgida var. sullivantii ‘Goldsturm’, respectively. Although similar foliar mineral nutrient concentrations were required to maximize growth of both hibiscus and rudbeckia
Seedlings of six provenances of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] (Escambia Co., Ala., Santa Rosa Co., Fla., Wayne Co., N.C., Burlington Co., N.J., New London Co., Conn., and Barnstable Co., Mass.) were grown in controlled-environment chambers for 12 weeks under 16-hour photoperiods with 16-hour days/8-hour nights of 22/18 °C, 26/22 °C, 30/26 °C, 34/30 °C or 38/34 °C. Considerable variation in height, foliage color, and overall plant size was observed among plants from the various provenances. Seedlings from the two most northern provenances (Massachusetts and Connecticut) were most heat sensitive as indicated by decreasing growth rates at temperature regimes >22/18 °C. In contrast, plants from New Jersey and the three southern provenances (North Carolina, Florida, and Alabama) exhibited greater heat tolerance as indicated by steady or increasing growth rates and greater top and root dry weights as temperature regimes increased above 22/18 °C. Growth rates of seedlings from the four aforementioned provenances decreased rapidly at temperature regimes >30/26 °C suggesting low species tolerance to high temperatures. There were no significant differences in seedling dry matter production among provenances when temperature regimes were ≥34/30 °C. Net shoot photosynthesis and dark respiration of plants did not vary by provenance; however, net photosynthesis was temperature sensitive and decreased at temperature regimes >26/22 °C. Foliar respiration rates increased as temperature increased from 22/18 °C to 26/22 °C, but then remained relatively constant or decreased at higher temperature regimes. Plants at temperatures ≥34/30 °C exhibited severe stunting, chlorosis, and necrosis on branch tips. However, tissue concentrations of N, P, K, Ca, Mg, Fe, Zn, Cu, and Mn generally increased with temperature regimes >30/26 °C indicating that mineral nutrient concentration was not a limiting factor at high temperatures.
were ground into a fine powder for the determination of B and other mineral nutrient concentrations in the tissues. Seedling height (cm) and taproot length (cm) were measured using a scaled ruler. Leaf gas exchange measurements. After 6 weeks of
seeding. Fig. 3. The effect of adequate and elevated levels of potassium on plant height of greenhouse-grown red romaine lettuce plants harvested 56 d after seeding. K influence on mineral nutrient concentration in leaf tissue. Increasing levels of K