hydroponics showed that root iron reducing capacities were highly negatively correlated with visual chlorosis scores from field trials ( Ellsworth et al., 1997 ) and provide a better screening ability than H + ion release ( Ellsworth et al., 1998 ). Moreover
Strawberries (Fragaria xananassa Duch. .Osogrande.) were grown hydroponically with three NO3-N concentrations (3.75, 7.5, or 15.0 mM) to determine effects of varying concentration on NO3-N uptake and reduction rates, and to relate these processes to growth and fruit yield. Plants were grown for 32 weeks, and NO3-N uptake and nitrate reductase (NR) activities in roots and shoots were measured during vegetative and reproductive growth. In general, NO3-N uptake rates increased as NO3-N concentration in the hydroponics system increased. Tissue NO3-. concentration also increased as external NO3-N concentration increased, reflecting the differences in uptake rates. There was no effect of external NO3-N concentration on NR activities in leaves or roots during either stage of development. Leaf NR activity averaged ~360 nmol NO2 formed/g fresh weight (FW)/h over both developmental stages, while NR activity in roots was much lower, averaging ~115 nmol NO2 formed/g FW/h. Vegetative organ FW, dry weight (DW), and total fruit yield were unaffected by NO3-N concentration. These data suggest that the inability of strawberry to increase growth and fruit yield in response to increasing NO3-N concentrations is not due to limitations in NO3-N uptake rates, but rather to limitations in NO3 - reduction and/or assimilation in both roots and leaves.
Abstract
Highest quality of plants of greenhouse-grown ‘Captain Gallant’ iris as measured by plant growth and root and foliar quality were produced at pH levels of 8.0 and 9.0 in hydroponic culture and at pH levels of 7.0 to 9.5 using field soil. Plant foliage appeared to increase in quality with increases in alkalinity.
Nitrogen (N) is often the most limiting mineral nutrient for taro growth. Two experiments were carried out under hydroponics conditions to determine the effects of varying solution N levels and N form on taro (Colocasia esculenta L. Schott cv. Bun Long) growth and foliar nutrient concentrations for 42 days. In the first experiment, taro plants were grown at six NH4NO3 levels (0, 0.25, 0.5, 1.0, 2.0, and 4.0 mm N). In the second experiment, taro plants were grown at a total N level of 3 mm with five nitrate (NO3-): ammonium (NH4+) percent molar ratios (100:0, 75:25, 50:50, 25:75, and 0:100). In the N level experiment, dry matter and leaf area increased up to 2 mm N and then decreased at the highest N level. The reduced growth of taro at the highest N level was attributed in part to a high NH4+ level that reduced uptake or translocation of cations, such as Ca2+, Mg2+, and Mn2+. Nitrogen concentration in leaf blades increased with increasing N levels. The critical foliar N concentration that coincided with 95% of maximum growth based on a quadratic model was 40.4 g·kg-1 (dry weight basis). In the N form experiment, NO3-: NH4+ ratios of 75:25 or 100:0 favored greater plant growth compared to other treatments. Taro plants grown in NH4+-rich solutions drastically acidified the solution pH, and had retarded growth and smaller leaf area compared to those grown in NO3--rich solutions.
Greenhouse hydroponics and field experiments were conducted to determine how nitrogen (N) fertilizer treatments affect tomato (Lycopersicon esculentum Mill.) growth, yield, and partitioning of N in an effort to develop more sustainable fertilization strategies. In a hydroponics study, after 4 weeks in nitrate treatments, shoot dry weight was five times greater at 10.0 than at 0.2 mm nitrate. An exponential growth model was strongly correlated with tomato root growth at all but 0.2 mm nitrate and shoot growth in 10 mm nitrate. Root dry weight was only 15% of shoot biomass. In field studies with different population densities and N rates, height in the 4.2 plants/m2 was similar, but shoot weight was less than in the 3.2 plants/m2. At 12 weeks after planting, shoot fresh weight averaged 3.59 and 2.67 kg/plant in treatments with 3.2 and 4.2 plants/m2, respectively. In 1998, final tomato yield did not respond to N rate. In 1999, there was a substantial increase in fruit yield when plants were fertilized with 168 kg·ha-1 N but little change in yield with additional N. Nitrogen content of the leaves and the portion of N from applied fertilizer decreased as the plants grew, and as N was remobilized for fruit production. Both studies indicate that decreasing N as a way to reduce N loss to the environment would also reduce tomato growth.
constantly recirculating nutrient solution ( Dholwani et al., 2018 ; Mohammed and Sookoo, 2016 ; Resh, 1978 ). Because hydroponics systems are generally used in greenhouses, more absolute control over environmental variables, such as temperature, is an
Date, S. Terabayashi, S. Matsui, K. Namiki, T. Fujime, Y. 2002 Induction of root browning by chloramine in Lactuca sativa L. grown in hydroponics J. Jpn. Soc. Hort. Sci. 71 485 489 Feng
://edis.ifas.ufl.edu/fe1027 > Heuvelink, E. Dorais, M. 2005 Crop growth and yield 85 144 Tomatoes doi: https://doi.org/10.1079/9780851993966.0085 Jensen, M.H. 1997 Hydroponics worldwide 719 730 International Symposium on Growing Media and Hydroponics
; General Hydroponics, Santa Rosa, CA) provided continuous aeration. Bamboo stakes (40 cm tall) were used to provide physical support for the plants, which were secured as needed with twist ties. Plants were grown for 8 weeks inside two walk-in growth
vegetables for Europe ( Patowary, 2013 ). Techniques such as hydroponics, soilless substrate production, mulching, and drip irrigation turned the region into what it is today ( Fig. 3 ). The region also benefits from a large labor force from nearby countries