Hydroponic growing systems have the potential to maximize phytomass production of peanut (Arachis hypogea) for Controlled Ecological Life Support Systems (CELSS). Two greenhouse experiments were conducted with plant nutrients supplied in a modified Evan's solutionusing a nutrient film technique. The objective of this research was to determine the effect of hydroponic growing systems on pod and foliage yield of `New Improved Spanish' and `Georgia Red' peanut. Sub-objectives were to evaluate (i) the impact of channel size and (ii) the impact of gradation in pore size on the separation of the rooting zone from the zone of gynophore development. The treatments consisted in the first experiment of a wide channel (122 by 15 by 46 cm) fitted with a perforated (3.0mm diam.) PVC grid; a narrow channel (122 by 15 by 15 cm) either fitted with a perforated grid or without a grid. For 'New Improved Spanish' peanut dry foliage yield tended to be higher in the wide channel treatment (0.33 kg/sq m). But the narrow channel yielded the highest mean pod dry weight (0.12 kg/sq m). Pore sizes of the screens ranged from infinity (no screen). perforated grid, square mesh. filtering screen (75u) and solid screen (no pores). For `Georgia Red' peanut, the impact of gradation in pore size of screens was variable: pod number was highest with the filtering (food) screen (216/sq m) but pod dry weight was highest for the square mesh treatment (0.09 kg/sq m). Foliage yield was significantly greater for the filtering (food) screen (1.12 kg/sq m) than in any of the other treatments. The findings of the research indicate that use of screens is feasible and will not retard pod development. The presence of a perforated grid tended to result in lower phytomass production for `New Improved Spanish' peanut.
A.A. Trotman, C.E. Mortley, D.G. Mortley, P.P. David, and P.A. Loretan
D. Mortley, P. Loretan, C. Bonsi, W. Hill, and C. Bonsi
An experiment was conducted in environmental growth chambers to study the response of sweet potato to relative humidity (RH). Twenty-four vine cuttings of `TI-155' sweet potato were planted in growth channels in a modified half Hoagland's solution using the nutrient film technique. Plants were exposed to constant RH levels of 50% or 85%. Temperature regimes of 20/22 C were maintained during the light/dark periods with an irradiance level of 600 umol m-2 s1, and a 14 hr/10 hr photoperiod. Plants were harvested 120 days after planting and yield data was taken. High RH (85%) resulted in significant increases in number of storage roots/plant, storage root fresh and dry weight, single leaf photosynthesis and stomatal conductance than at 50% RH. Foliage dry weight and leaf temperature was higher at 50% than 85% RH.
C. Morris, D. Mortley, P. Loretan, C. Bonsi, and W. Hill
The potential of the sweet potato as a food source for future long-term manned space missions is being evaluated for the National Aeronautics and Space Administration's (NASA) Controlled Ecological Life Support System (CELSS) Program. Several experiments have shown that the sweet potato can be grown hydroponically. However, an evaluation of the NASA fan-shaped Biomass Production Chamber (BPC) channel was initiated to determine if channel depths influenced the yield of hydroponically grownsweet potatoes. Three channel depths were studied, 5 cm (2 in) standard NASA BPC channel, 10 cm (4 in) channel and 15 cm (6 in) channel. The experiment consisted of one replication. The results show that channel depth does effect the yield of storage roots. The 15 cm depth channel provided the most consistent yield with all channels having significantly different fresh storage root yields in the replicate.
Audrey A. Trotman, P. David, D. Mortley, and J. Seminara
In a greenhouse experiment, the effect of the addition of higher levels of potassium (K) in the replenishment stock used to supply nutrients in a nutrient film technique system was examined. For this study, `TU-82-155' sweetpotato was grown hydroponically for 120 days under four nutrient application/replenishment treatments: 1) REG—solution was changed at 14-day intervals and volume allowed to fluctuate; 2) MHH—replenishment with 10× concentrate of a modified half Hoagland solution (MHH) or with water to regain set volume (30.4 liters) and maintain set point of electrical conductivity (EC, 1050–1500 μmho); 3) MHH + 2K—daily replenishment with 10× concentrate of a modified half Hoagland solution (MHH) or with water to regain the set volume and adjust EC to 1400 followed by application of 50 ml of a 2K stock solution to an EC of 1500; 4) MHH/2K—replenishment with 10× concentrate of a modified half Hoagland solution that incorporated the 2K component or with water to regain set volume (30.4 liters) and maintain set point of electrical conductivity (EC, 105–1500 μmho). The storage root yield (g fresh weight per plant) was significantly higher when the 2K treatment was incorporated with the 10× MHH stock. The storage root yield averaged 324.8 g/plant compared with a yield of 289.6 and 252.9 g/plant, respectively, for the REG and MHH nutrient application protocol. As in earlier experiments, the MHH treatment was comparable to the REG protocol, validating the use of a replenishment approach for nutrient supply in hydroponic sweetpotato culture.
D.G. Mortley, C.B. Smith, and K.T. Demchak
The effects of fertilizer placement on growth and nutrient uptake of `Count II' tomatoes (Lycopersicon esculentum Mill.) were evaluated in a 3-year study. Fertilizer was applied broadcast at two rates or banded in two bands at two widths or in four bands, or applied in combinations of sidedressing or broadcasting with banding of N, P, and K at 56, 112, or 224 kg·ha-1 each. Total fruit yield for the 112 kg·ha-1 banded treatment was 24% higher than that for the same rate broadcast and similar to yield for 224 kg·ha-1 broadcast. Treatments involving combined placements, wider bands, or four bands produced yields similar to that for 112 kg·ha-1 banded, but the 56 kg·ha-1 banded with two 56 kg·ha-1 sidedressings had the highest yield. Leaf concentrations and plant contents of N, P, and K and percentage recovery of quantities applied were generally higher in treatments involving banding or sidedressing when compared to broadcasting. Leaf Mn was much higher in banded or sidedressed than for broadcast treatments but was lower when 112 kg·ha-1 was applied in four bands than in two. Only with Mg and Mn were leaf concentrations and plant contents highly correlated. With 112 kg·ha-1 banded, 31.2% of the N, 5.8% of the P, and 44.7% of the K applied were taken up, compared to 12.5%, 2.3%, and 17.2%, respectively, for double this rate broadcast.
Audrey A. Trotman, P.P. David, D.G. Mortley, and D. Douglas
In developing a nutrition management strategy that reduces the quantity of products entering the waste management stream, gaining an understanding of the patterns and fluctuations of nutrient levels and crop growth characteristics is essential. In a greenhouse study, `TU-82-155' sweetpotato was grown hydroponically for 120 days in three nutrient application–replenishment treatments: l) REG-solution changed at 14-day intervals and volume allowed to fluctuate; 2) daily replenishment with 10× concentrate of a modified quarter Hoagland's solution (MQH) or with water to regain set volume (30.4 liters) and maintain set point of electrical conductivity [(EC); 1050 to 1200 μmho]; 3) daily replenishment with l0× concentrate of a modified half Hoagland's solution (MHH) or with water to regain the set volume and maintain the set point of EC. There were no statistically significant differences among nutrient application protocols for storage root count, fresh and dry weights, and percent dry matter. The MHH treatment consistently yielded significantly higher leaf biomass and pencil roots (>1 mm in diameter), indicating a higher potential for increased storage root yield. A nutrient application protocol using treatment 2 has potential for reduced waste production if used in hydroponic sweetpotato production. The plants from the MQH treatment initiated vegetative buds at a significantly later date than in the other treatments and generally showed evidence of suppressed plant development.
P.P. David, A.A. Trotman, D.G. Mortley, D. Douglas, and J. Seminara
A study was initiated in the greenhouse to examine the effects of five
D.G. Mortley, P.A. Loretan, C.K. Bonsi, W.A. Hill, and C.E. Morris
The effects of within-channel spacings (WCS; 13, 18, 25 cm) and between-channel spacings (BCS; 13, 25,38 cm) on yield and linear growth rate of sweetpotatoes [Ipomoea batalas (L.) Lam.] grown by use of the nutrient film technique (NFT) were evaluated. Storage root count, fresh and dry weights, and linear growth rate, expressed as root area, declined linearly in response to decreased BCS, while fresh and dry foliage weight decreased linearly and quadratically as spacing was reduced within the growth channels. Neither linear growth rate on a canopy area basis nor the edible biomass index was significantly affected by WCS or BCS.
D.G. Mortley, C.K. Bonsi, P.A. Loretan, W.A. Hill, and C.E. Morris
Growth chamber experiments were conducted to study the physiological and growth response of sweetpotato [Ipomoea batatas (L.) Lam.] to either 50% or 85 % relative humidity (RH). Vine cuttings of T1-155 were grown using the nutrient film technique in a randomized complete-block design with two replications. Temperature regimes of 28/22C were maintained during the light/dark periods with irradiance at canopy level of 600 μmol·m-2·s-1 and a 14/10-hour photoperiod. High RH (85%) increased the number of storage roots per plant and significantly increased storage root fresh and dry weight, but produced lower foliage fresh and dry weight than plants grown at 50% RH. Edible biomass index and linear growth rate (in grams per square meter per day) were significantly higher for plants grown at 85 % than at 50% RH. Leaf photosynthesis and stomatal conductance were higher for plants at 85 % than at 50% RH. Thus, the principal effect of high RH on sweetpotato growth was the production of higher storage root yield, edible biomass, growth rate, and increased photosynthetic and stomatal activity.
A.A. Trotman, P.P. David, D.G. Mortley, and G.W. Carver
In a greenhouse study, continuous use of the same plant nutrient solution for hydroponic culture of sweetpotato was investigated to determine the effect on storage root yield, plant growth and nutrient solution composition. Plants were grown for 120 days under continuous flow from a 30.4-liter reservoir. Plant growth was compared when nutrient solution was changed at 14-day intervals and when nutrient solution was not changed but nutrients replenished through addition of a Modified half-Hoagland's (N:K=1:2.4) plant nutrient solution when volume in reservoir was -10 liters. Storage root yield was significantly decreased (181 vs 310.3 g/plant) and foliar biomass was significantly increased (372.4 vs 2% g/plant) when nutrient solution was not changed Nitrate and phosphate concentrations decreased in the plant nutrient over the duration of the experiment while sulfate and chloride concentrations increased. Salinity and electrical conductivity were monitored at 2-day intervals and increased with duration of the crop. Increased foliage production may have been the result of nitrogen replenishment going largely for foliage rather than storage root production. It may be that continuous use of the same plant nutrient solution as practiced in this study, resulted in lowered phosphate and nitrate concentrations that limited uptake of these ions by sweetpotato plants, thus reducing yield