Search Results

You are looking at 111 - 120 of 350 items for :

  • hydroponics x
  • Refine by Access: All x
Clear All
Free access

D. Schwarz, H.-P. Kläring, M.W. van Iersel, and K.T. Ingram

An increase in nutrient solution concentration to produce high-quality fruit vegetables, such as tomatoes, may reduce growth and yield. One reason might be inhibition of photosynthesis, but results of photosynthesis studies in the literature are inconsistent. In this study, we investigated growth and photosynthesis of whole `Celebrity' and `Counter' tomato [Lycopersicon esculentum (L.) Mill.] plants in response to nutrient solution concentration, measured as electrical conductivity (EC). The effects of two levels of photosynthetic photon flux density (PPF = 400 or 625 μmol·m-2·s-1) on plant response to nutrient solution EC in a range between 1.25 to 8.75 dS·m-1 in a series of four experiments in gas exchange chambers placed in larger growth chambers were examined. Increasing PPF enhanced tomato growth and photosynthesis but increasing EC diminished them. Reduction of dry weight was 1.9% to 7.3%, while plant photosynthesis was reduced between 1.7% and 4.5% for each 1 dS·m-1. Increasing EC did not decrease dry matter content and leaf photosynthesis. Mean plant dry matter content ranged between 70 and 95 g·kg-1, and net leaf photosynthesis on the last measurement day was between 7.5 and 11.3 μmol·m-2·s-1, depending on experiment. The decrease in whole plant photosynthesis with an increase in EC was caused by decreased leaf area but not by a decrease in leaf photosynthesis.

Free access

Johan M.H. Stoop and David M. Pharr

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.

Free access

Michael A. Grusak, Brian W. Stephens, and Donald J. Merhaut

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.

Free access

Jinghua Guo, Yan Yan, Lingdi Dong, Yonggang Jiao, Haizheng Xiong, Linqi Shi, Yu Tian, Yubo Yang, and Ainong Shi

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

Open access

Fernanda Trientini and Paul R. Fisher

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

Full access

Richard V. Tyson, Danielle D. Treadwell, and Eric H. Simonne

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

Full access

Marie Abbey, Neil O. Anderson, Chengyan Yue, Michele Schermann, Nicholas Phelps, Paul Venturelli, and Zata Vickers

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

Open access

William B. Miller, Wanxiang Lu, and Dongqin Tang

. 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

Full access

Kent D. Kobayashi

-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

Open access

Kellie J. Walters, Bridget K. Behe, Christopher J. Currey, and Roberto G. Lopez

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