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  • Author or Editor: M.B. Kirkham x
  • Journal of the American Society for Horticultural Science x
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Abstract

Chrysanthemum plants (Chrysanthemum morifolium Ramat. cv. Bright Golden Anne) were grown for 84 days in plastic pots containing media treated with inorganic fertilizers or liquid sewage sludge, added at a rate of 50, 100, or 200 ml/week, to determine if sludge could be used as a fertilizer. Plants grown with sludge at all application rates had higher N and lower K concentrations compared to plants grown with inorganic fertilizers. Leaf concentration of P, Ca, Mg, Fe, Zn, Cu, Cd, Ni, and Pb of plants grown with 50 ml sludge/week were similar to plants receiving inorganic fertilizers. As sludge application rate increased, leaf concentrations of Fe and Cu increased of plants grown in media consisting of all sand or all peat and Zn increased in leaves of plants grown in the standard greenhouse media (1 soil: 1 sand:l peat, by volume). Sludge-treated media had a higher pH and extractable Cu concentration, and a lower extractable K concentration, than media without sludge. Plants receiving 50 ml sludge/week grew as well as plants grown with inorganic fertilizers.

Open Access

Abstract

The effects of water deficits were examined on osmotic regulation of germinating seedlings of tomato (Lycopersicon esculentum Mill cv. Campbell 1327). Seed were germinated in aerated water and then grown for an additional 2 days in Petri dishes. The germinated seeds were then transferred to water potentials of 0 to −6 bars in 2-bar increments. Mannitol and water was used to obtain the desired water potential of the media. Water relations, growth rates and reducing sugars, non-reducing sugars, amino acids, proline, nitrates, phosphates, potassium, and electrical conductivity were determined for roots and shoots at different water stresses. As water stress increased, osmotic adjustment occurred in the roots which accounted for the maintenance of turgor and growth. During the same period, little adjustment occurred in the shoots and consequently growth decreased. Turgor potential was highly correlated with growth rates for both plant parts. All solutes measured, except proline, generally increased in the roots and decreased in the shoots as water stress increased. Proline increased in both plant parts during the same period. Thus, solute regulation occurred during water deficits. Osmotic regulation in germinating tomato seedlings appears to be an adaptive feature during periods of water stress.

Open Access

Abstract

Two species of tomato, Lycopersicon chilense Dun. and Solanum pennellii Corr., which have drought-resistant characteristics, were compared to the commercial tomato, Lycopersicon esculentum Mill. cv. Campbell 1327, to evaluate the effects of water deficits on germination and early seedling growth at 25, 30, and 35°C. Five levels or water stress (0, −2, −4, −6, and −8 bars) were maintained by solutions of polyethylene glycol (PEG) 6000. Germination of dry seed was inhibited more by water stress than by growth of the germinated seedlings of each species. Germinated seed of all species were able to continue growth at 35° plus water stress at all levels, while germination under the same conditions was totally suppressed. The water-sensitive phase of germination occurred just prior to radicle emergence. Emergence was not affected by sowing germinated seed in a drying soil; but sowing dry seed under the same conditions resulted in a decrease in emergence. Germination and seedling growth of L. chilense and S. pennellii were more sensitive to water stress than L. esculentum at 25°. At 30 and 35°, L chilense, S. pennellii and L. esculentum had similar rates of germination and similar amounts of early seedling growth.

Open Access

Measurements of soil water content near the soil surface often are required for efficient turfgrass water management. Experiments were conducted in a greenhouse to determine if the dual-probe heat-pulse (DPHP) technique can be used to monitor changes in soil volumetric water content (θv) and turfgrass water use. `Kentucky 31' Tall fescue (Festuca arundinacea Schreb.) was planted in 20-cm-diameter containers packed with Haynie sandy loam (coarse-silty, mixed, calcareous, mesic Typic Udifluvents). Water content was measured with the DPHP sensors that were placed horizontally at different depths between 1.5 and 14.4 cm from the surface in the soil column. Water content also was monitored gravimetrically from changes in container mass. Measurements started when the soil surface was covered completely by tall fescue. Hence, changes in θv could be attributed entirely to water being taken up by roots of tall fescue. Daily measurements were taken over multiple 6- or 7-day drying cycles. Each drying cycle was preceded by an irrigation, and free drainage had ceased before measurements were initiated. Soil water content dropped from ≈0.35 to 0.10 m3·m-3 during each drying cycle. Correlation was excellent between θv and changes in water content determined by the DPHP and gravimetric methods. Comparisons with the gravimetric method showed that the DPHP sensors could measure average container θv within 0.03 m3·m-3 and changes in soil water content within 0.01 m3·m-3.

Free access