Hydroponic Culture System Research Articles

Hydroponic culture of wild rice (Zizania palustris L.) and its application to studies of silicon nutrition and fungal brown spot disease

The mineral nutrient requirements of wild rice (Z. palustris var. interior L.) grown on flooded soils in Minnesota are poorly understood. A hydroponics culture system was developed to study the effects of silicon on the growth and fungal brown spot disease (FBS) resistance of wild rice. Wild rice was grown to maturity using a modified Hoagland’s solution. Plants attained a height of 1.4 m and had healthy roots, leaves and inflorescences containing viable seeds. Plant height and biomass were approximately 80 and 46%, respectively, of plants grown in cultivated paddies. A method was developed to reliably infect leaves and stems of hydroponically grown wild rice with Bipolaris oryzae, the pathogen causing FBS. Silicon amendments did not significantly increase growth and had no apparent effect on resistance to FBS. Key words: Bipolaris oryzae, hydroponic culture, plant nutrition, silicon, wild rice, Zizania palustris

Growth Analysis of Congeneric Annual and Perennial Grass Species

Summary 1. A growth analysis was conducted on seven annual/perennial pairs of grasses (six congeneric and one pair taken at random) grown in a hydroponic culture system under constant, productive conditions, in order to investigate the mechanisms responsible for the higher relative growth rate (RGR) of annuals as compared to perennials. 2. All the production parameters (RGR, relative leaf production rate, unit leaf rates), were higher in annuals than in perennials. There were very few differences between the two life forms in biomass allocation to the different organs (except a higher allocation to sheaths in perennials)

Maize White Line Mosaic Virus Transmission to Maize Seedlings in Hydroponic Culture

A hydroponic culture system and the effects of nonchemical and chemical treatments of root inoculum on transmission of maize white line mosaic virus (MWLMV) were evaluated. Root pieces (0.2 g) from 8- to 10-wk-old infected Seneca Chief sweet corn (Zea mays var. saccharata) plants were used as inoculum to transmit MWLMV to roots of sweet corn test seedlings. MWLMV was transmitted consistently to seedling roots (>90%) as shown by enzyme-linked immunosorbent assays (ELISA). The ELISA values (absorbances at 405 nm) of root inocula and inoculated roots were not significantly correlated (.)

A System for Continuous Production of Root-Knot Nematode Juveniles in Hydroponic Culture

A hydroponic culture system that enables ready production and retrieval of freshly hatched, infective root-knot nematode juveniles was developed. Meloidogyne javanica-infected tomato plants produced at least 100,000 juveniles per day for as long as 3 mo. Juveniles reinfected roots within the culture system, which possibly accounts for the extended period of production. The hydroponically grown nematodes retained characteristic infectivity and host range. This culture system is useful when a cohort of uniform-age juveniles is required or for analyses in which high numbers of nematodes are needed

Tomato (Lycopersicon esculentum Mill., cv. 'Better Bush') Plant Response to Root Restriction

Observations presented here describe changes in the growth of Lycopersicon esculentum Mill., cv. ‘Better Bush’, at the onset of root-restriction stress. Plants were grown in either 1500 cm 3 (control) or 25 cm 3 (treated) containers in a flow-through hydroponic culture system (FTS). Seeds were imbibed, germinated, held for 13 d in sterile germination bags, then placed into the FTS and designated day zero plants. Plants grown in the FTS were harvested, every 7 d, from day 11 to day 46. Plant height, root and shoot weights, leaf areas, leaf lengths, branching and flowering were measured to illustrate morphological changes that occurred in response to root-restriction stress. Plants restricted to a 25 cm 3 root volume experienced a marked stress after 18 d in the FTS. A reduction in leaf elongation was evident and preceded the time (prior to day 25) when maximum dry weights were attained by restricted root systems. Control plants had greater leaf areas and plant dry weights than those of root-restricted plants after day 18. Treated plants showed no significant increase in dry weights from day 32 to the end of the experiment. Between day 18 and 25 the root: shoot ratio for the treated plants dropped below that of the controls. Adventitious rooting was evident in treated plants by day 25. Roots of the treated plants showed an apparent waterlogging indicated by browning of roots by day 32. Root turnover followed as the primary root system was replaced by adventitious roots. The number of branches or flowers did not differ between control and treated plants. The timing of the events described here can be used to further the study of specific physiological responses of tomato plants to root-restriction stress.

Some characteristics of Rhizobium leguminosarum isolates from uninoculated field-grown lentil

A total of 229 Rhizobium leguminosarum isolates from the lentil-growing region of West Asia-North Africa (WANA) were evaluated for their symbiotic effectiveness and for salt and heat tolerance. These included 65 isolates from the ICARDA culture collection, strains from international collections, and fresh isolates from soils and nodules of lentil ( Lens culinaris L.) growing in Turkey, Syria, Jordan and Egypt. Enumeration of rhizobia populations in lentil fields of Egypt, Jordan and Turkey using most probable number (MPN) technique indicated a range of 3.1 × 10 1 to 6.9 × 10 5 viable rhizobia g −1 soil. Only 13% of the 61 soils sampled contained < 10 3 cells g −1, while 20% of soils had > 10 5 rhizobia g −1. Lentil fields in Jordan contained higher average population densities than other areas evaluated. The symbiotic effectiveness of all collected isolates was evaluated on lentil cv. ILL 16 in an aseptic N-free hydroponic gravel culture system. A greater proportion (up to 50%) of highly effective isolates was found in samples from eastern Turkey and Jordan: samples from Syria and Egypt mainly contained rhizobia with moderate to poor N 2 fixing capacity. Of the isolates collected from all locations, 44% were of low effectiveness; only 21% were classified as superior fixers. Distinct variations in salt and heat tolerance were observed for isolates from different regions. A greater proportion of Egyptian isolates and international standard strains grew at 35°C. Only 9 of 229 isolates grew at 40°C; 8 of these came from the southern Nile valley in Egypt. Isolates from Jordan and Turkey were more sensitive to 0.5% NaCl in the growth medium than the others, of which 30–50% were tolerant. Few isolates grew with 1.0% NaCl: most of these came from Syria. None of the heat- or salt-tolerant isolates was among the most effective N 2 fixers.

4965962 Hydroponic culture system: Shizuka Akagi, Chiba, Japan assigned to Q P Corporation

4965962 Hydroponic culture system: Shizuka Akagi, Chiba, Japan assigned to Q P Corporation

Components of relative growth rate and sensitivity to nitrogen availability in annual and perennial species of Bromus.

Two grass species, the annual Bromus sterilis and the perennial Bromus erectus, were grown from seeds for 28 days in a hydroponic culture system at 1 and 100 μM NO3- in the nutrient solution. At 100 μM NO3-, the relative growth rate (RGR) of the perennial was 30% lower than that of the annual. This was only the consequence of the higher specific mass of its leaves, since its leaf mass ratio was higher than that of the annual and the unit leaf rates (ULR), calculated on an area basis, were similar for the two species. At 1 μM, the RGR of the annual was 50% lower than at 100 μM, while that of the perennial was not significantly lower. This was due mainly to a lower ULR for the annual. while for the perennial ULR was the same in both treatments. These differences between the two species were all the more striking in that the differences in total nitrogen concentrations and nitrate reductase activities between the two treatments were very similar for both species. These different responses together with differences in the nitrogen productivity of the two species suggest that the level of nutrient availability may play an important role in the distribution of these Bromus species in natural habitats.

Relationship Between Cowpea Root Systems and Mycorrhizal Dependency

Abstract A hydroponic experiment was conducted to determine the relationship between mycorrhizal dependency (MD) of cowpea [Vigna unguiculata (L.) Walp.] cultivars and their root morphology. Seeds of 19 cowpea cultivars with known MD levels were inoculated with Glomus fasciculatum and Bradyrhizobium in seedling trays. Twelve-day-old seedlings were transferred to a hydroponic culture system, where they were grown for 5 weeks. Leaf area, length of taproot, total root length, root weight, root abundance, average length of fine roots, number of nodules formed on lateral roots, and total nodule weight differed among cultivars. Less than 5% of the root length was colonized by mycorrhizal fungus in all cultivars. Average length of fine roots was negatively correlated with MD of cowpea cultivars; however, only 27% of the variability in MD was explained by this variable. Therefore, root morphology did not appear to determine MD in cowpea.

Micronutrients

The influence of nutrient solution pH on growth and nutrient uptake of Chrysanthemum mori folium ‘Bright Golden Anne’ in a recirculating hydroponic culture system was investigated. Plants were grown in two nutrient solutions (Hoagland's and Petersr Hydro‐Sol) adjusted daily to pH levels of 4.5, 5.5, 6.5 or 7.5 for a period of five weeks. Growth parameters (shoot, root, and total fresh and dry weights; leaf number and area) and nutrient uptake (total‐N, NO3 and organic‐N, P, K, S, Ca, Mg, Mn, Fe, B, Cu, Zn, Na and Mo) were maximal for both nutrient solutions when a pH of 6.5 was maintained.

Screening and selection of pearl millet for root associated bacterial nitrogen fixation

There are several reports of genotypic variability in grass species for their ability to achieve associations with N 2-fixing soil bacteria. These findings imply that plant breeding may be useful in enhancing these associations and thereby making available plant germplasms needed for agronomic and physiological studies of associative N 2-fixation in grasses. When the N 2-fixing bacterium Azospirillum brasilense (strain JM 125) was used as inoculum, differences were found among selfed lines of pearl millet ( Pennisetum americanum (L.) K. Shum.) for an ability to support bacterial acetylene reduction activity (ARA) when assayed in enclosed seedling agar tubes. These lines were selfed again or hybridized. Although line to line discrepancies were seen, the ARA of these lines and hybrids when categorized into high or low groups matched the activity of their original parental lines. Also, the selfed and hybrid groups obtained from high ARA lines supported higher numbers of bacteria and lost greater quantities of 14C from their roots than did those groups obtained from low ARA lines. Two of these lines, one having high ARA and one having low ARA, were grown in soil in the greenhouse and were found to differ in their respective ability to support ARA by the soil N 2-fixing microbes. However, overall ARA of the high line was quite low unless analyzed in a hydroponic culture system at low O 2 tensions.

Root Diseases of Vegetables in Hydroponic Culture Systems in North Carolina Greenhouses

Root Diseases of Vegetables in Hydroponic Culture Systems in North Carolina Greenhouses

ROUTINE PRODUCTION OF AXENIC VESICULAR‐ARBUSCULAR MYCORRHIZAS

SummaryA compact autoclavable hydroponic culture system is described for the production of axenic vesicular‐arbuscular mycorrhizas formed between Trifolium parviflorum and Glomus caledonius. Liquid is circulated by means of a low pressure air supply and sterility is maintained by glass fibre air‐filters. Provision is made for sampling of the nutrient solution for analysis and sterility tests.

Hydroponic sand culture systems for mycorrhizal research

Tomato plants were inoculated withGlomus fasciculatus mycorrhizal fungi while growing in sand through which recycled nutrient solution was automatically passed several times daily. Concentration of P and N in the solution were maintained at relatively low levels. Roots of inoculated plants became highly infected with mycorrhizal fungi, and yield parameters were significantly increased with inoculation over uninoculated control plants.

Canopy and Seasonal Profiles of Nitrate Reductase in Soybeans (Glycine max L. Merr.)

Nitrate reductase activity of soybeans (Glycine max L. Merr.) was evaluated in soil plots and outdoor hydroponic gravel culture systems throughout the growing season. Nitrate reductase profiles within the plant canopy were also established. Mean activity per gram fresh weight per hour of the entire plant canopy was highest in the seedling stage while total activity (activity per gram fresh weight per hour times the total leaf weight) reached a maximum when plants were in the full bloom to midpod fill stage. Nitrate reductase activity per gram fresh weight per hour was highest in the uppermost leaf just prior to full expansion and declined with leaf position lower in the canopy. Total nitrate reductase activity per leaf was also highest in the upper-most fully expanded leaf during early growth stages. Maximum total activity shifted to leaf positions lower in the plant canopy with later growth stages.Nitrate reductase activity of soybeans grown in hydroponic systems was significantly higher than activity of adjacent soil grown plants at later growth stages, which suggested that under normal field conditions the potential for nitrate utilization may not be realized. Nitrate reductase activity per gram fresh weight per hour and nitrate content were positively correlated over the growing season with plants grown in either soil or solution culture. Computations based upon the nitrate reductase assay of plants grown in hydroponics indicated that from 1.7 to 1.8 grams N could have been supplied to the plant via the nitrate reductase process. The harvested seed contained 1.1 to 1.2 grams N per plant. Thus, based on previous estimates of approximately 32% of the final N distribution being in the vegetative plant parts, the estimated input of reduced nitrogen via the enzyme assay was in agreement with the actual N accumulation.The amount of calculated N(2)-fixation by nodules per season with plants grown in hydroponics was less than 2% of the computed nitrate reduced via leaf nitrate reductase. Thus, the level of nitrate in the nutrient solution appeared to be quite inhibitory to N(2)-fixation.

Seasonal Nutrient Uptake and Accumulation Patterns in Soybeans1

Field hydroponic gravel culture systems were used to determine nutrient uptake and accumulation in soybeans (Glycine max (L.) Merr.). Uptake of N, P, K, Ca, and Mg were low during the first 30 days after emergence. At initial flowering, nutrient uptake increased sharply, reaching maximum uptake rates between full bloom and midpod fill. Uptake of N, P, and K generally declined through later development stages while Ca and Mg uptake remained high or even increased. The difference in uptake patterns of the macronutrients during later development stages appeared to reflect differences in mobility and translocation of the nutrients.Percent N in the total tops gradually declined from the seedling stage and leveled off shortly after full bloom. Phosphorus concentration increased during the first 30 days after emergence, peaked at initial flowering, declined until mid‐pod fill, and leveled off through the remaining sampling dates. Phosphorus toxicity symptoms were evident at initial flowering with the highest nutrient level imposed. Percent K increased slightly from the seedling stage until full bloom and then declined. Calcium concentration increased until initial flowering, then declined and leveled off during later growth stages while the Mg concentration decreased gradually from the seedling stage through the green bean stage. The concentration of micronutrients (Fe, Mn, Zn, Cu, and B) generally declined from the seedling stage through the green bean stage.