interactions on the growth and marketability of anthurium; thus, the present study had the objective of determining the response of container-grown plants to varying proportions of anions [nitrate (NO 3 − ), phosphate (H 2 PO 4 − ), and sulphate (SO 4 2− )] in
pH and preventing drift is, therefore, an important aspect of nutrient management. Plants affect root zone pH primarily through differential uptake of cation and anion nutrients ( Haynes, 1990 ; Lea-Cox et al., 1996 ; Marschner, 2012 ; Rengel, 2003
Research indicates P and S leach rapidly from soilless media amended with ordinary superphosphate (2). Since these elements are in the form of anions, an amendment with a high anion exchange capacity may reduce their leaching from soilless media. In the following study, an anion exchange resin was used to test this theory.
Currently, formulation of inorganic fertilizers is based on cation amounts such as NH4, K, Mg, Ca, Fe, MN Cu, and Zn, whereas anion species and amounts are viewed, with few exceptions, as necessary fillers. The delivery of cations in the nutrient solution is associated with an anion such as Cl, SO4, NO3, PO4 or CO3. These anions at higher concentrations can result in different growth responses by altering the rhizosphere pH, soluble salts, and influencing the uptake of both cations and anions. The impact of these anions has not been extensively studied in the formulation of inorganic fertilizers. Several experiments assessed the effect of SO4 and Cl on root and shoot growth and development of bedding plants represented by petunia, impatiens, and vinca. In all treatments, plant height, shoot and root dry weight, and flower number decreased with an increase in Cl concentration. Root morphology was marked by fewer total roots and shorter primary and secondary roots when grown with Cl anions compared to the plants grown with SO4 anions. This indicates that anions have a larger role in determining optimum fertilizer formulation than previously believed. This information provides an additional tool in formulating fertilizers for greenhouse bedding plant production.
Greenhouse rose plants, `Bull's Eye', budded on the rootstocks Rosa manetti and R. × `Natal Briar', were grown in containers filled with a peat-based growing medium. The plants were irrigated with a 0.5× Hoagland solution salinized with a fixed 12-mM Na solution made up of seven ratios of NaCl, Na2SO4, and NaNO3 (100:0, 50:50:0, 0:100:0, 0:50:50, 0:0:100, 50:0:50, and 33:33:33). The results after four flushes of growth and flowering showed higher dry weight productivities in R. manetti plants. Salt composition (i.e., counter-anion ratios) significantly affected the dry weight yield of `Natal Briar' plants, with those irrigated with 100% Na2SO4 and NaNO3 having the highest and lowest values, respectively. While the plants budded on R. manetti did not show significant responses to salt composition, there was a strong tendency for higher dry weight yields in binary salt (anion) compositions. Leachates collected throughout the study showed similar pH (7.5) and electrical conductivities (4.7 dS/m) for all salt treatments. Leachate Cl- concentrations were linearly correlated with Cl- application, whereas leachate Na+ concentrations remained similar among treatments. Plants on R. manetti accumulated less leaf Na+ and Cl- than in R. × `Natal Briar' plants, with lower values observed, in general, in plants irrigated with solutions containing Na2SO4.
The objective of this study was to evaluate the role of chloride (Cl-) and other anions in soil water on the incidence and severity of Rio Grande Gummosis (RGG) in grapefruit (Citrus paradisi MacFadyen) trees. White `Marsh' grapefruit trees on sour orange (C. aurantium Lush.) rootstock were grown on two-row raised beds. Due to differential rates of K application (as KCl), the trees received various rates of Cl- ranging from 0 to 156 kg·ha-1 per year. Soil water was sampled using suction lysimeters at 120- and 180-cm depths. The severity of RGG was evaluated 18 months following the application of various rates of KCl. The concentration of Cl- in soil water samples varied from 16.2 to 617 mg·L-1, with mean concentrations across all treatments of 160.7 and 188.4 mg·L-1 for 120- and 180-cm depth water samples, respectively. The concentrations of Cl- and other anions (
was basic and increased the pH, whereas impatiens ( Impatiens wallerana Hook. F.) had intermediate effects to geranium and petunia. A major process by which plants affect root zone pH is through imbalanced uptake of cation and anion nutrients ( Haynes
disproportionation (a type of redox reaction) to produce molecular oxygen and H 2 O 2 , which is further catalyzed by peroxidase and catalase ( Vallino et al., 2009 ). SOD activity is usually induced along with overproduction of superoxide anions ( Benes et al., 1995
ammonium (NH 4 + ) and nitrate ions were leached with 120 mL of DI water, which was slightly less than the total column volume (170 mL). With the exception of Brown and Pokorny (1977) , no other studies solely focused on anion or cation transport in
generation of reactive oxygen species (ROS), such as hydroxyl radicals (·OH), superoxide anions (O 2 ·- ), and hydrogen peroxide. Although well known for the damage they cause to cells, ROS are considered signalling molecules in plant stress perception ( Zhou