sawdust mulch (224 ppm); however, all treatments were well above the recommended sufficiency level for soil P in northern highbush blueberry ( Hart et al., 2006 ). Soil cations. Soil K was higher when the plants were fertilized with the high rate of either
Aluminum (Al) and phosphorus (P) interactions were investigated in mycorrhizal (M) and nonmycorrhizal (NM) highbush blueberry (Vaccinium corymbosum L.) plantlets in a factorial experiment. The toxic effects of Al on highbush blueberry were characterized by decreased shoot, root, and total plant dry mass. Many of the negative effects of Al on plant root, shoot, and total dry matter production were reversed by foliar P and N application, indicating P or N uptake were limited by high Al concentration. However, Al-mediated growth reduction in P-stressed plants indicated that the restriction of P uptake by high Al may not have been the only mechanism for Al toxicity in this experiment. Root Al and P concentration were negatively correlated in NM but not M plantlets, suggesting mycorrhizal infection may alter P uptake processes. Al uptake was also affected by mycorrhizal infection, with more Al accumulating in M plantlet roots and leaves. Correlations among foliar ion concentrations were also affected by mycorrhizal fungal infection.
Aluminum and P interactions were investigated in mycorrhizal (M) and nonmycorrhizal (NM) highbush blueberry plantlets in a factorial experiment. The toxic effects of Al on highbush blueberry were characterized by decreased shoot, root, and total plant dry weight. Many of the negative effects of Al on plant root, shoot, and total dry-matter production were reversed by foliar P and N application, indicating P or N uptake were limited by high Al concentration. However, Al mediated growth reduction in P-stressed plants suggested that the restriction of P uptake by high Al may not have been the only mechanism for Al toxicity in this experiment. Root Al and P concentration were negatively correlated in NM plantlets but not in M plantlets, suggesting mycorrhizal infection may alter P uptake processes. Al uptake also was affected by M infection, with more Al accumulating in M plantlet roots and leaves. Correlations among foliar ion concentrations were also affected by M fungal infection.
A factorial experiment was conducted to determine the effect of aluminum (0 and 600 μM) and media (sand, and 1:1 sand:soil) on mycorrhizal (M) and non-mycorrhizal (NM) highbush blueberry plantlets. There were no differences in nutrient uptake and total plant dry weight between M and NM plantlets. However, more root growth, as determined by dry weight, was observed in M than NM plantlets. The plantlets growing in sand had more dry weight than did those in the soil medium. Although the root growth and shoot growth were reduced by the 600-μM Al treatment, the direct effect of Al on plantlet growth was not clear due to Al and P interactions. Plant nutrient uptake was reduced by high concentrations of Al, suggesting that high Al concentration limited the ability of roots to acquire most of the nutrients. Mycorrhizal epidermal cell infection levels of 15% to 20% were maintained in the roots in soil medium but decreased to about 5% over the 6 weeks of the experiment in the sand medium. Although M plantlets accumulated more Al in their roots, Al was readily transported to the leaf tissues of M and NM plantlets.
Because cucumber mosaic virus (CMV) affects southernpea (Vigna unguiculata) grown in the southeast, plants were preconditioned with different nutrient solutions from germination to the flowering stage, 24 DAT (days after transplanting) and rub inoculated with CMV. Symptoms were observed at a rate of 1/5, 1/5, 4/5, and 4/5 (observed infected plants/plants infected) in the Al, NH4, NO3, and Na treatments, respectively. At 67 DAT, ELISA detected CMV at a rate of 5/5, 5/5, 4/5, and 4/5 (detected infection/plants infected) of the Al, NH4, NO3, and Na treatments, respectively. The interaction of inoculation and preconditioning was nonsignificant for fresh or dry weight (P > 0.10); however, nutritional preconditioning significantly (P < 0.01) affected the fresh and dry weight. These preliminary data suggest that nutritional preconditioning affects southernpea plants' reaction to CMV.
Control of preemergence damping-off caused by Phytophthora parasitica Dastur was investigated on three bedding plant species in a 1 peat: 1 vermiculite medium (v/v) limed at 3 kg·m–3 and drenched with aluminum at 10, 25, or 50 meq Al/100 cm3 medium. Aluminum as Al2(SO4)3 was applied as a drench at 0.75, 1.9, or 3.75 g/150 ml water to the surface of infested medium in 650-cm2 plug trays (1300-cm3 tray volume). All concentrations of aluminum were effective in controlling preemergence damping-off of snapdragon (Antirrhinum majus L.) and vinca (Catharanthus roseus G. Don, Madagascar periwinkle), but only 50 meq Al+3/100 cm3 medium was effective for petunia (Petunia ×hybrida Hort. Vilm.-Andr.). At 4 days after seeding and drenching with aluminum sulfate, exchangeable aluminum was 0, 0.5, and 2.03 meq Al+3/100 g medium, respectively, for the three concentrations used. Control of damping-off of snapdragon and vinca with 10 meq Al+3/100 cm3 medium with no detectable exchangeable aluminum 4 days after application suggests that P. parasitica was suppressed by aluminum early in the host–pathogen interaction, whereas petunia was susceptible to damping-off for a longer period before seedling emergence. Aluminum was not phytotoxic to vinca, snapdragon, or petunia grown in a limed medium.
Abstract
Boron, calcium, and naphthalene acetamide (NAAm) foliar sprays were applied alone or in combination to ‘York Imperial’ apple trees under Eastern Pennsylvania orchard conditions. Mineral content of the leaves and fruit and number of cork spots in the fruits were determined.
B applications alone or in combination with Ca and/or NAAm increased leaf and fruit B content. All Ca applications increased the leaf Ca content, the fruit P content, and the leaf and fruit K and Fe content, but had no effect on fruit Ca content. NAAm sprays increased the leaf Mg and Al content. NAAm applied in combination with Ca increased the leaf Ca content. The NAAm effects appear to be associated with the valence of the element, having no effect on monovalent elements, some effect on divalent elements, and the strongest effect on the trivalent element, Al.
Th B-Ca and B-Ca-NAAm spray treatments reduced the number of cork spots per fruit. Regression analysis indicated that as the B and Ca content increased in the leaves, and fruit peel and flesh the cork spots decreased. Cork spots increased as the P and K content of the leaves increased. Core data showed that cork spots decreased as the B and Mg content increased and the B × Mg interaction decreased. There was no relation between number of cork spots and the leaf and fruit content of Mn, Fe, Cu, Zn, or Al, despite significant effects of the treatments on these elements.
Abstract
‘York Imperial’ apple trees on EM 26 rootstock were grown in large, outdoor sand cultures for 3 years. All combinations of N at 2, 4, or 8 me/1 as all NO3 or as 3/4NH4 - 1/4 NO3; Ca at 1, 8 or 16 me/1; and B at 0.05 or 0.5 ppm were supplied in solution, with other nutrients in normal supply. Levels of N and Ca and their interactions affected growth under NO3 nutrition. Growth was greatly reduced under NH4 nutrition, but was little affected by levels of N and Ca. Leaf tissues were analysed for N, P, K, Ca, Mg, Al, B, Cu, Fe, Mn, and Zn. The average, 3-year over-all effect of NH4 nutrition was to increase leaf concentration of all elements except K, Al, and Mn. Source of N altered the main effects and interactions between levels of N and Ca. B had little effect on concentration of other elements in the leaves.
of OA secretions ( Maejima et al., 2014 ). Different plant species are likely to employ different Al tolerance mechanisms and enact different forms of interaction with mineral nutrients such as P. P is a major limiting nutrient of crops mainly because
Research was conducted to investigate the interaction of water-soluble fertilizer and medium composition on vegetative growth and the concentration of mineral nutrients in media and in leaves of a hybrid moth orchid (Phalaenopsis Blume.). The vegetatively propagated `TSC 22' clone of the hybrid Phalaenopsis Atien Kaala plants 15 cm in leaf spread were potted in a medium consisting of either 100% fine grade douglas fir [Pseudotsuga menziesii (Mirb.) Franco] bark or a mixture of 7 fir bark: 3 sphagnum peat (by volume). Plants were fertigated at each irrigation with a soluble 10N-13.1P-16.6K, 20N-2.2P-15.8K, or 20N-8.6P-16.6K fertilizer, or a 2N-0.4P-1.7K liquid fertilizer at a common N rate of 200 mg·L-1. After 1 year in a greenhouse, plants grown in the bark-peat medium produced more leaves, greater fresh weights (FW), and larger total leaf areas than those in 100% bark. In the bark medium, the 20N-2.2P-15.8K fertilizer resulted in plants of the highest quality, despite its low P concentration (22 mg·L-1). When grown in bark-peat, the two fertilizers (20N-2.2P-15.8K and 20N-8.6P-16.6K) containing urea as part of their N source (10% and 52%, respectively) resulted in plants with 40% to 50% heavier shoot FW and 40% larger leaf area than the other fertilizers without urea. With any given fertilizer, plants had similar root FW in both media. Media and fertilizers had limited or no effect on the concentrations of mineral nutrients in the second mature acropetal leaves, except P, which nearly doubled in leaves of plants grown in 100% bark. High leaf Mg concentration was associated with low Ca. Water extracts from the bark-peat medium had lower pH, higher electrical conductivity, and much higher levels of NH4-N, Ca, Fe, Na, Cl, B, and Al than those from 100% bark. Extracts from the bark medium did not have detectable levels of NO3-N, whereas extracts from the bark-peat medium all had similar levels of NH4-N, regardless of which fertilizer was applied. Levels of P and K were not different between the two media.