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William R. Argo and John A. Biernbaum

Hybrid impatiens (Impatiens Wallerana Hook. F.) were planted in a peat-based medium containing two dolomitic liming materials (1.8 kg Ca(OH)2·Mg(OH)2/m3 or 8.4 kg CaCO3·MgCO3/m3) and subirrigated for 17 weeks using four irrigation-water sources (IWSs) with varied bicarbonate alkalinity, Ca2+, Mg2+, and SO4-S content and three water-soluble fertilizers (WSFs) that contained (in mg) 200N-20P-200K/liter but a variable NH4: NO3 ratio, Ca2+, Mg2+, and SO4-S content. The factorial arrangement of the IWS and WSF resulted in a range of Ca2+, Mg2+, and SO4-S concentrations varying by a factor of 10. After 8 weeks, medium pH ranged from 4.5 to 8.5. The maximum critical medium pH for PO4-P uptake was 7.4 to 7.7, which probably was due to a change in most of the water-soluble P to the less-available HPO4 2- form. Lime type did not affect the long-term increase in medium pH, Ca2+, and Mg2+ concentrations with nutrient solutions containing low NH4 +-N and high Ca2+ and Mg2+. The carbonate lime buffered the medium pH and Ca2+ and Mg2+ concentrations with nutrient solutions containing high NH4 +-N and low Ca2+ and Mg2+ compared to that measured with the hydrated lime. With both lime types, there was a linear increase in tissue Ca and Mg as the applied concentrations of the various nutrient solutions increased from 18 to 210 mg Ca2+/liter and 7 to 90 mg Mg2+/liter. The relationship was similar for both lime types up to week 8, after which tissue Ca and Mg decreased more rapidly with the hydrated lime and low solution Ca2+ and Mg2+ compared to that of the same carbonate lime treatments. The minimum critical SO4-S concentration in the applied nutrient solution for plant uptake was 30 to 40 mg S/liter. Below this concentration, tissue S decreased rapidly; above, there was little effect on tissue S.

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Genhua Niu, Raul I. Cabrera, Terri W. Starman, and Charles R. Hall

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William R. Argo

Maintaining medium pH and nutrient concentrations at levels acceptable for growth are important for producing vigorous transplants in the shortest time. Medium chemical properties, such as cation-exchange capacity, aeration, liming materials, preplant fertilizer, irrigation-water sources, water-soluble fertilizers, and plant species, interact to affect medium pH and nutrient management. However, these chemical properties do not affect medium pH or the nutrient supply simultaneously or with equal intensity. The objective of this review is to consider key chemical properties of container media and their affects on pH and nutrient management initially and over time.

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Reagan W. Hejl, Benjamin G. Wherley, James C. Thomas, and Richard H. White

deficit (0.3 × ET a ) irrigation levels using three irrigation water sources (RO, sodic, and saline) and 2) determine whether application of TE could mitigate turfgrass quality decline under deficit irrigation. Materials and Methods This research was

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William L. Berndt

of seven experimental irrigation water sources, each having a differing EC ( EC iw ), sodium adsorption ratio, and so on. Water sources (treatments) consisted of sea water taken from the Gulf of Mexico at Fort Myers Beach, Fla. (26.4500°N, 81.9508°W

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Warren E. Copes, Andrew Ristvey, Patricia A. Richardson, Bruk E. Belayneh, Haibo Zhang, John Lea-Cox, and Chuanxue Hong

production in diverse geological, geographical, and climatic regions. Literature Cited Argo, W.R. Biernbaum, J.A. 1996 The effect of lime, irrigation-water source, and water-soluble fertilizer on the pH and macronutrient management of container root media

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Michael A. Arnold, Bruce Lesikar, Ann Kenimer, Don C. Wilkerson, and Mitchell W. Goyne

The nursery/greenhouse industry is the fastest growing segment of U.S. agriculture. Consumer demand for excellent product quality requires luxury applications of water and agricultural chemicals. These cultural practices tend to yield significant volumes of runoff rich in nutrients and pesticides. A capture and recycle system at the Nursery/Floral Crops Research and Education Center at Texas A&M University was fitted with 12 subsurface flow (SSF) and 12 free-surface flow (FSF) wetland cells. Constructed wetland cells provided substantial reduction of runoff nutrient concentrations without increasing electrical conductivity, an indicator of salinity. Growth of Iris pseudacorus L. and Canna ×generalis L.H. Bailey during spring growth was greater in the FSF wetland cells, while that of Colocasia sp. Fabr. was greater in the SSF wetland cells. Equisetum hyemale L. grew equally well in both cell types. Direct reuse of nursery runoff reduced the number of Ilex vomitoria Ait. `Nana' reaching marketable size in 2.3-L containers. Interactions among irrigation water sources and container media types for growth indices occurred for Juniperus procumbens `Green Mound' and I. vomitoria `Nana', but not for Raphiolepis indica L. `Carmelita'.

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Andrew Koeser, Sarah T. Lovell, Michael Evans, and J. Ryan Stewart

In recent years, biocontainers have been marketed as sustainable alternatives to petroleum-based containers in the green industry. However, biocontainers constructed with plant materials that are highly porous in nature (e.g., peat, wood fiber, straw) tend to require more frequent irrigation than conventional plastic products. As irrigation water sources become less abundant and more expensive, growers must consider water consumption in any assessment of their economic and environmental viability. This project evaluated plant growth and total water consumption for nine different biocontainers (seven organic alternatives, and two recently developed bioplastic alternatives) and a plastic control used to produce a short-term greenhouse crop, ‘Yellow Madness’ petunia (Petunia ×hybrida). Dry shoot weight and total water consumption differed by container type, with some of the more porous containers (wood fiber, manure, and straw) requiring more water and producing smaller plants by the end of the trial period. Intuitively, the more impervious plastic, bioplastic, and solid rice hull containers required the least irrigation to maintain soil moisture levels, though shoot dry weights varied among this group. Shoot dry weight was highest with the bioplastic sleeve and slotted rice hull containers. However, the latter of these two containers required a greater volume of water to stay above the drying threshold. Findings from this research suggest the new bioplastic sleeve may be a promising alternative to conventional plastic containers given the current production process.

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William R. Argo and John A. Biernbaum

Hybrid impatiens (Impatiens wallerana Hook. F.) were planted into media containing two dolomitic liming materials {hydrated [Ca(OH)2 and Mg(OH)2] or carbonate (CaCO3 and MgCO3) lime} and subirrigated for 17 weeks with four irrigation water sources (IWS) and three water-soluble fertilizers (WSF). The WSF contained 200N–20P–200K mg·L-1 but varied in NH4 +-N content (50%, 25%, or 3%, respectively). Depending on the IWS and lime type used in the media, root-medium pH ranged from 4.5 to 6.0, 4.8 to 7.1, and 6.0 to 8.5 when treated with WSF containing either 50%, 25%, or 3% NH4 +-N, respectively, between 8 and 17 weeks after planting. The accumulation of NH4 +-N and NO3 --N in the root medium was different for treatments receiving the same WSF and depended on root-medium pH. The critical root-medium pH for NH4 +-N accumulation was between 5.4 and 5.7, and for NO3 --N, accumulation was between 5.3 to 5.9. Above this pH, minimal NH4 +-N concentrations were measured in the medium, even with 50% or 25% NH4 +-N WSF, while below this pH, NH4 +-N began to accumulate in the medium with a corresponding decrease in the NO3 --N concentration. The NH4-N: NO3-N ratios in the WSF had minimal effect on shoot fresh and dry weights. Tissue N concentration was higher with the higher NH4-N : NO3-N ratio WSF at all four sampling dates. There was a linear relationship between higher tissue N and lower root-medium pH with the same WSF, possibly due to differences in the ratio of NH4-N: NO3-N actually taken up by the plant.

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Xuan Liu and Catherine Grieve

Two statice cultivars, Limonium perezii cv. Blue Seas and L. sinuatum cv. American Beauty, were grown in greenhouse sand tanks to determine the effect of salt stress on carbohydrate accumulation and partitioning. For the first experiment, irrigation waters were prepared to simulate typical saline-sodic drainage effluent in the San Joaquin Valley of California with electrical conductivities of 2.5, 7, 11, 15, 20, 25, and 30 dS·m−1. A second experiment compared responses to two types of irrigation waters with salinity levels of 2.5, 6, 8, 10, 12, 16, and 20 dS·m−1: 1) San Joaquin Valley drainage waters, and 2) solutions mimicking concentrations of Colorado River water, a major irrigation water source for southern California. In addition to the presence of myo-inositol and three common sugars (fructose, glucose, and sucrose), chiro-inositol was for the first time isolated and identified in leaf and root tissues of both Limonium species. As salinity increased from 2.5 to 30 dS·m−1, leaf chiro-inositol concentration increased from 6.4 to 52.8 and from 2.6 to 72.9 μmol·g−1 dry weight for L. perezii and L. sinuatum, respectively, suggesting that chiro-inositol contributes substantially to osmotic adjustment in the stressed plants. Meanwhile, leaf myo-inositol concentration remained low in both species and showed little response to salinity. Before salt stress, the seedlings contained little chiro-inositol, indicating that salt enhanced chiro-inositol synthesis per unit of biomass formation. Significant (P ≤ 0.05) increasing trends for fructose and glucose and a decreasing trend for sucrose with increasing salinity were observed in the leaves of L. perezii but not L. sinuatum. As a result, the leaves of L. perezii had higher glucose and fructose but lower sucrose levels than that of L. sinuatum. However, no significant (P > 0.05) salt effect was found on the sum of the three common sugar concentrations in either species. Therefore, the accumulation of chiro-inositol resulted in a change in carbon partitioning among the soluble carbohydrates (i.e., the ratio of leaf chiro-inositol over a sum of the three common sugars rose from 0.034 to 0.29 dS·m−1 and from 0.012 to 0.32 dS·m−1 for L. perezii and L. sinuatum, respectively, as salinity increased from 2.5 to 30 dS·m−1). Salt stress did not affect starch accumulation and caused no carbon reserve deficiency. Furthermore, it was observed that salinity increased chiro-inositol phloem transport. The chiro-inositol response might be a physiological process for Limonium salt adaptation. The types of saline irrigation waters (i.e., sodium sulfate-dominated waters vs. a sodium chloride system) appear to have little effect on carbohydrate accumulation and partitioning in L. perezii.