The fleshy parenchyma tissue of celery [Apium graveolens L. var. dulce (Mill.) Pers.] petioles is the major storage tissue for the sugar alcohol mannitol and for the hexoses, glucose and fructose. In this study, we found that plants grown in the soilless mixture, Promix, fertilized weekly with a nutrient solution, or grown in a hydroponic container culture, differed in carbohydrate composition. However, plant growth was not affected. Higher mannitol and lower hexose concentrations were present in petioles from plants grown hydroponically. This was true in petioles that did not differ in total soluble carbohydrate concentration. The ratio of mannitol to hexose concentration in petioles was ≈2-fold higher for hydroponically grown plants compared to Promix-grown plants, and the higher ratio was maintained during the entire 12-week experimental period. Carbohydrate partitioning was also affected by petiole development within the plant. Sucrose and hexose concentrations were highest in mature petioles, whereas mannitol was relatively high in all petioles except the oldest ones. Because the mineral solution applied to the Promix-grown plants had a lower total salt concentration compared to hydroponically grown plants, we postulated that the salt concentration of the mineral solution might be an important factor affecting C partitioning in celery petioles. When plants were grown hydroponically at two different salt concentrations [electrical conductivity (EC) = 2.7 and 6.0 mS·cm-1], high mannitol-to-hexose ratios were observed in celery petioles of plants grown at high salt concentration (EC = 6.0 mS·cm-1), a result supporting the hypothesis that the salt environment might alter mannitol and hexose concentrations in a coordinated way. These data are consistent with the hypothesis that elevated mannitol levels may be a significant component of plant adjustment to salt stress, possibly adding osmotic adjustment and preventing inactivation of metabolic processes.
Snap beans (Phaseolus vulgaris L.) are a food source that can contribute to dietary Ca requirements in humans. Factors which might enhance the concentration of Ca in snap bean pods have been investigated by measuring whole-plant net Ca influx, whole-plant Ca partitioning, and various growth parameters in two snap bean cultivars—Hystyle and Labrador—that differ in pod Ca concentration. Plants were grown hydroponically under controlled environmental conditions while being provided adequate quantities of Ca. The concentration of Ca in pods (dry weight basis) was 52% higher in `Hystyle', relative to `Labrador', but net Ca influx throughout crop development or total plant Ca content at three stages of development were similar in both cultivars, demonstrating that pod Ca concentration differences were not due to differences in total plant Ca influx. However, `Hystyle' partitioned more total plant Ca to pods, relative to `Labrador'. Calcium flux analysis also revealed that daily rates of whole-plant net Ca influx gradually declined throughout the period of pod growth in both cultivars; this decline was not related to whole-plant water influx. These results suggest that enhancements in whole-plant net Ca influx during pod growth and/or enhancements in the xylem transport of absorbed Ca to developing pods could increase the Ca concentration of snap bean pods.
Hydroponics is an increasingly important field for counterseason vegetable production because of its efficiency in fertilization, water, and space use. Furthermore, it can overcome the disadvantages of soil culture, such as continuous cropping
boomers ( Garden Media Group, 2016 ). In this context, small-scale hydroponics is becoming more popular among homeowners and provides a market opportunity for transplants and growing systems. Closed hydroponics systems are suitable for indoor gardening
Ashcroft, 2006 ). However, plant densities and arrangements in hydroponics are different from field production ( Resh, 2004 ), and sizing the hydroponic sub-system may depend on plant type, density, and arrangement and their effect on water requirements
Aquaponics incorporates hydroponics (soilless plant production) and aquaculture (fish production) into a closed-loop, recirculating system ( Rakocy et al., 2006 ). Waste from the fish production provides the primary nutrients for the crop plants
. Expt. 5: Hydroponics. After 10 d of establishment in hydroponics, roots were exposed to 2000 mg⋅L –1 ethephon. After 10, 20, 40, and 80 min, stem tissue (1-cm segment beneath the second node) and the second leaf were harvested for analysis. Tissues
-related apps for research, extension, teaching, and industry are widely available. These apps deal with a myriad of subjects including food safety ( Albrecht et al., 2012 ), geographic information systems, image enhancement, hydroponics, scouting for insects
of the U.S. hydroponics industry, and 3) use historical trends and current practices to inform future perspectives. Historical Perspectives of U.S. CE and Hydroponic Production Although CE vegetable production has been reported to have originated
hydroponic system in early Aug. 2013 and were allowed to grow without any experimental treatments until adequate root and shoot development occurred. The PA treatment began on 29 Aug. 2013 and the experiment ended on 3 Oct. 2013. The hydroponics study was