, 2008 ). Therefore, we have conducted a hydroponics study to test the efficacy of SYTOX blue dye in differentiating the viable and dead leaf and root cells of ‘Mariner’ and ‘Penncross’ under salt stress using confocal microscopy. Leaves and roots ≈2.0 cm
Sanalkumar Krishnan and Emily B. Merewitz
David R. Hershey
Shoot or leaf cuttings can be rooted in flats of perlite under intermittent mist for use in a static solution culture system (Hershey and Merritt, 1986). However, removing perlite from the roots before transfer to hydroponics is tedious and damages the roots; also, all the perlite cannot be removed, which causes errors in dry mass and nutrient concentration determinations. A hydroponic propagation system was constructed of inexpensive, readily available materials that allowed rooting of large numbers of cuttings under intermittent mist.
K. Mattas, M. Bentes, G. Paroussi, and I. Tzouramani
The financial effectiveness of a soilless vertical bag system of hydroponics culture was evaluated for off-season strawberry (Fragaria ×ananassa Duch) production in heated greenhouses in northern Greece. Financial analysis revealed that the implementation of this soilless culture system instead of the traditional production system under plastic tunnels would not be profitable for Greek farmers due to its high initial investment and high fuel consumption. Sensitivity analysis indicated the importance of product price in affecting the magnitude of benefits, confirming the interest of farmers to produce off-season strawberries to market them when prices are likely to be higher. In addition, yield increase will have a positive effect upon farmers' income.
Hao Wang and Mary Ann Rose
Nutrient uptake and allocation patterns of Forsythia ovata × europaea `Meadowlark' grown in a recirculating hydroponic system in the greenhouse were observed for 5 months. Dormant rooted cuttings were placed in the system on 8 May 1995. The nutrient solution supplied (in mg·L–1) 100 N, 48 P, 210 K, 30 Mg, 60 Ca, 117 SO4, 3 Fe, 0.5 Mn, 0.15 Zn, 0.15 Cu, 0.5 B, 0.1 Mo. Solutions were completely replaced every 2 weeks. Leaves, stems, and roots were harvested for dry weight and nutrient analysis at monthly intervals. Nitrogen uptake and dry-weight accumulation in the roots increased throughout the experiment, reaching a maximum in the fifth month (September). Nitrogen uptake and dry-weight accumulation of leaves and stems increased rapidly throughout the first 3 months, then leveled off. Whole-plant N recovery (N taken up/N in hydroponics system) reached a maximum (58%) between 6 July and 3 August. N recovery in the hydroponics system was about 10 times greater than what we observed in related experiments with woody plants in typical production environments, suggesting that there is potential for manipulating fertilization and cultural practices to increase fertilization efficiency in woody ornamentals. Nutrient recovery and accumulation patterns of P and K also will be presented.
Lynette von Allmen and Tamara Thomsen
Seedling of “Cortland” and “Idared” apples (Malus domestica) were grown in hydroponics and the shoots and roots were evaluated for percent concentration of calcium. “Cortland” is reported to be efficient in calcium uptake in comparison to “Idared”, reputed to be less efficient in calcium uptake and utilization. The seedlings were grown in hydroponic solutions containing calcium ranging from 0.5 ppm to 3.0 ppm concentrations. The shoots and the roots of the seedlings were analyzed for calcium content after 45 days. “Idared” seedling roots and shoots had higher calcium content at 0.5 ppm. However, at 1.5 ppm and at 3.0 ppm “Cortland” seedlings appear to be more efficient at calcium uptake. Early screening may be a useful tool in helping apple breeders select future cultivars that are more efficient at calcium uptake
Kenneth B. Marcum
Relative salinity tolerance of 33 creeping bentgrass (Agrostis palustris Huds), one colonial bentgrass (A. capillaris L.), and one velvet bentgrass (A. canina L.) cultivars were determined via hydroponics in a controlled-environment greenhouse. After gradual acclimation, grasses were exposed to moderate salinity stress (8 dS·m-1) for 10 weeks to determine tolerance to chronic salinity stress. Relative dry weight of leaf clippings (RLW), percentage of green leaf area (GL), root dry weight (RW), and root length (RL) were all effective parameters for predicting salinity tolerance. Following 10 weeks of salinity stress, RLW was correlated with GL (r = 0.72), with RW (r = 0.71), and with RL (r = 0.66). The range of salinity tolerance among cultivars was substantial. `Mariner', `Grand Prix', `Seaside', and `Seaside II' were salt-tolerant, `L-93', `Penn G-2', `18th Green', and `Syn 96-1' were moderately salt tolerant, and `Avalon', `Ambrosia', `SR1119', `Regent', `Putter', `Penncross', and `Penn G-6' were salt sensitive.
Bedri Karakas, Riccardo Lo Bianco, and Mark Rieger
The effect of specific ion toxicity during salt stress was tested in the present study. The experiment was repeated twice, in 1996 and 1998, with `Nemaguard' peach seedlings and rooted cuttings grown in hydroponics under two NaCl concentrations (50 and 30 mm). Foliage was separated in symptomatic and symptomless leaves and the amount of sodium (Na+) and chloride (C1–) was determined. Significantly higher Na+ content was found in symptomatic than in symptomless leaves in both experiments, whereas in only two of the six cases was Cl– content higher in symptomatic than in symptomless leaves. The Na+ threshold for leaf scorch was somewhere between 4 and 6 mg·g–1 dry weight. Results indicated that Na+ accumulation, rather than Cl– accumulation, was associated with the familiar marginal and interveinal scorch symptoms seen in salt-stressed peach leaves.
Anita L. Hayden
Hydroponic and aeroponic production of medicinal crops in controlled environments provides opportunities for improving quality, purity, consistency, bioactivity, and biomass production on a commercial scale. Ideally, the goal is to optimize the environment and systems to maximize all five characteristics. Examples of crop production systems using perlite hydroponics, nutrient film technique (NFT), ebb and flow, and aeroponics were studied for various root, rhizome, and herb leaf crops. Biomass data comparing aeroponic vs. soilless culture or field grown production of burdock root (Arctium lappa), stinging nettles herb and rhizome (Urtica dioica), and yerba mansa root and rhizome (Anemopsis californica) are presented, as well as smaller scale projects observing ginger rhizome (Zingiber officinale) and skullcap herb (Scutellaria lateriflora). Phytochemical concentration of marker compounds for burdock and yerba mansa in different growing systems are presented.
Hillel Soffer and O. E. Smith
Lettuce, Lactuca sativa L., plants were grown in soil irrigated at various intervals with nutrient solution and in hydroponics culture. Increased nutrient level added to the soil increased seed yield but did not give a corresponding increase in seedling performance.
Hydroponically propagated seed, although heavier than soil propagated seed, were relatively poor in vigor and germinability. A positive linear correlation was found between N levels (5-15 meq) and seed yield, weight per seed, and seedling vigor. Amounts of amino acids and lipids were not positively correlated with nutrient supply, N level, or seedling vigor. Lettuce seed weight was a useful parameter in predicting seedling vigor only within a seed lot obtained from plants grown under the same environmental and nutritional conditions.
J. Frick and C.A. Mitchell
Due to its short time to flower (14-18 days) and rapid maturation cycle (50-55 days), dwarf rapid-cycling brassica (Brassica napus) is under consideration as a candidate oilseed crop for NASA's Controlled Ecological Life Support Systems program. Recent work has focused on defining a set of optimum environmental conditions which permit increased crop yield in terms of g·m-2d-1 of edible biomass. A wide range of environmental variables have been considered including lamp type, CO2 level, nutrient solution pH, and planting density. In addition, nitrogen nutrition regimes have been manipulated with respect to nitrogen concentration (2 to 30 mM), source (NH4 + and/or NO3 -), and time of stepwise changes in nitrogen level (day 14 to 28). The highest seed oil content (42% DW basis) has been found under limiting nitrogen levels (2 mM). However, the low nitrogen inhibits overall seed production potential. Different cultural techniques also have been compared, including solid-substrate, passive wicking hydroponics versus liquid culture systems. Trials are underway to assess crop growth and development under the “best set” scenario of environmental conditions. At present, the highest seed yield (10.6 g·m-2d-1) has been obtained using solid-substrate hydroponic systems under a combination of metal halide and high-pressure sodium lamps. Constant CO2 enrichment to 1000 μmol·mol-1 did not increase crop yield rate.
Research supported in part by NASA grant NAGW - 2329.