Rooted cuttings of Nemaguard peach [Prunus persica (L.) Batsch.] were grown in 0.18-, 0.36-, 0.90-, and 2.40-liter containers for 16 weeks to study the influence of root confinement on growth, gas exchange, water uptake, and leaf carbohydrate and nutrient content. An automatic nutrient-solution dispensing system was used to ensure uniform fertility among treatments and to prevent drought stress. Leaf area and stem length were reduced by root confinement 6 to 7 weeks after transplanting, and differences among treatments increased throughout the experiment. Final tree dry weights were reduced by 51% over a 13-fold reduction in rooting volume, but dry weight partitioning was largely unaffected. A temporary limitation to CO2 assimilation (A) and leaf conductance (g) was observed just after budbreak, but consistent reductions in A and g for confined trees did not occur until after week 11. Sorbitol and starch accumulated earlier in leaves of trees in smaller containers than larger containers. Despite similar fertility, concentrations of all nutrients except N and Cu were reduced ≈2-fold for trees in 0.18-liter containers compared to other treatments. However, characteristics of nutrient deficiency were not observed on any trees, and growth reduction with no change in leaf nutrient content was observed in other treatments. It was concluded that the initial mechanisms limiting growth were not gas exchange rates, levels of nonstructural carbohydrates, or drought stress, although nutrient deficiency may have contributed to growth limitation in trees with severely confined root systems.
Chelator-buffered nutrient solutions were used to study the effect of different levels of Zn activity in the rhizosphere on growth and nutritive responses of various tissues of sour orange seedlings. The seedlings were grown for 3 months in a growth chamber in a hydroponic culture containing from 5 to 69 μm and 5 to 101 μm total Zn in Expts. 1 and 2, respectively. Zn+2 activities were calculated with a computerized chemical equilibrium model (Geochem-PC), and buffered by inclusion of a chelator, diethylenetriamine pentaacetate (DTPA), at 74 and 44 μm in excess of the sum of Fe, Mn, Zn, Cu, Ni, and Co in Expts. 1 and 2, respectively. The use of DTPA-buffered solutions proved successful in imposing varying degrees of Zn deficiency. The deficiency was confirmed by leaf symptomatology, leaf chemical analyses, i.e., <16 mg·kg-1 Zn, and responses to foliar sprays and application of Zn to the roots. Growth parameters varied in their sensitivity to Zn deficiency, i.e., root dry weight < leaf number and white root growth < stem dry weight < leaf dry weight < shoot elongation and leaf area. The critical activities, expressed as pZn = -log(Zn+2), were ≈10.2±0.2 for root dry weight, 10.1±0.2 for leaf number and white root growth, 10.0±0.2 for stem dry weight, 9.9±0.2 for leaf dry weight, and 9.8±0.2 for shoot growth and leaf area. Increases in growth were observed in response to Zn applications even in the absence of visible Zn-deficiency symptoms. Seedlings containing >23 mg·kg-1 Zn in leaves did not respond to further additions of Zn to the nutrient solution. Zinc foliar sprays were less effective than Zn applications to the roots in alleviating severe Zn deficiency because foliar-absorbed Zn was not translocated from the top to the roots and thus could not correct Zn deficiency in the roots.
Sweetpotato[Ipommabatatas (L.) Lam.] is a major subsistence crop in southern Africa, where iron and zinc deficiency in humans is an important health problem. A cultivar of sweetpotato that is suited for subsistence farming in this region and that is high in iron and zinc could be an important means of combatting these deficiencies. As part of a program of the International Potato Center (CIP) to develop such a cultivar, we are working to identify the high and low range of iron and zinc in sweetpotato cultivars grown throughout the world by testing a number of cultivars for these nutrients. Subsidiary objectives include determining the heritability of iron and zinc levels and surveying the variability in the levels of these nutrients from root to root on the same plant, from plant to plant of the same cultivar, from the proximal to the distal end of a given root, and from cambium to cortex.
Many people want to use hydroponics in production of plants but often are hobbyists with limited access to the reagents necessary to formulate a nutrient solution. Several readily available commercial fertilizers and chemicals with tomato-(Lycopersicon esculentum Mill.) as the test plant were used to develop a nutrient solution. A 20-8.8-16.6 IN-P-K) general purpose fertilizer was added (1 g/liter) to deionized water to make a basic solution. This solution was fortified with slow-release fertilizer (approx. 17N-2.6P-8.5K with Ca, Hg, and minor elements) at 1 g/liter added directly to hydroponics vessels. Tomato developed severe foliar symptoms of Ca deficiency in this medium. Addition of CaSO4 or CaCO3 at 0.5 or 1 g/liter to give a solid phase of these chemicals in the vessels prevented development of symptoms of Ca deficiency; however, plants now showed symptoms of Mg deficiency. Addition of MgS0 at 0.25 g/liter to the basic solution prevented symptoms o Mg deficiency. Analyses confirmed that leaf N, P, K, Ca, and Mg were sufficient.
This solution was as good as Hoagland's No. 1 solution for growth of tomato, marigold, and cucumber and was better than Hoagland's solution for growth of corn and wheat.
Monitoring the nutrient status of a crop by soil and tissue analysis is an important tool in maximizing yields and avoiding nutrient deficiencies or toxicities. A nutritional management system is presented that uses a computer database to compile periodic soil and leaf tissue analyses to assist in the development of rational fertilizer recommendations for banana and macadamia nut orchards. Database management allows the Extension Agent to organize parameters (soil type, rainfall, elevation, tree age, tree spacing, and previous fertilizer practices) used in nutritional recommendations for individual farms. Graphs depicting nutrient trends over time and comparison of nutrient levels to nutritional standards, present visual illustrations of problems and encourage grower acceptance of fertilizer recommendations. Growers are also able to see graphic responses to application of corrective fertilizers and soil amendments.
Abstract
In ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder (DS) no over-all deficiency was in N, P, K, Ca, amino acids, proteins, sugars or phenols as compared with healthy (CK) trees. N, amino acid and protein contents were higher in DS than in CK spurs on 1- and 2-yearold limb sections. Relatively low nutrient levels in DS spurs on 3-4-year old limb sections indicated that translocation of nutrients to these spurs was restricted. Phenol contents were lower in DS than in CK spurs. P and K contents were higher in DS than in CK spur leaves.
Abstract
Seed of Lycopersicon esculentum Mill. ‘Champion’ and Petunia hybrida Vilm. ‘Snow Cloud’ were irrigated with either nonacidified solution (0.15, 0.30, or 0.45 ml) of 75% H3PO4·liter−1; or 0.11, 0.20, or 0.26 ml of 46.5% H2SO4·liter−1. Germination was not affected by acidification, yet seedling growth was enhanced for both species. Growing medium and plant shoots were analyzed for N, P, K, Ca, and Mg content. Although nutrient levels were affected by acidification, no nutrient deficiency or phytotoxicity due to irrigation water acidification was evident.
Abstract
In nutrient culture, growth of hybrid plants of Cymbidium and Phalaenopsis was optimal with 100 ppm N, 50-100 ppm K and 25 ppm Mg and optimal for Cattleya with 50 ppm each of N, K and Mg. Cymbidium plants developed N deficiency symptoms when supplied with 50 ppm N. K levels tested had little effect on growth responses. Mg at 100 ppm decreased growth of all 3 genera in comparison to 50 ppm.
Abstract
Phosphorus stress caused a general restriction of growth, pinkish tips and purplish leaves and was associated with low tissue P concn. Phosphorus concn for severe deficiency ranged from 0.034 to 0.08%, hidden hunger occurred from 0.09 to 0.11%, and sufficiency 0.12 to 0.27%. Phosphorus removed from the nutrient solutions was recovered in the plants. Soil test P at 50-70 kg/ha did not limit growth.
Abstract
Tagetes erecta L. cv. Golden Jubilee, Zinnia elegans Jacq. cv. Fire Cracker, and Petunia hybrida Hort. cv. Sugar Plum were grown in various sludge compost-based media based on fraction size. Growth determined by shoot dry weight was greatest in media containing greater portions of small compost particles. No nutrient deficiency symptoms or toxicity symptoms were observed. Shoot weight was increased by addition of a N-P-K fertilizer.