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Some countries have achieved success in growing strawberries hydroponically. These countries, however, attain a higher price for produce. Algae growth in strawberries and other hydroponic operations has been reported as a potential limitin factor. Three treatments were set up using a modified NFT system; a control in which algae was allowed to grow, a treatment physically covering all the nutrient solution to prevent contact with light, and a treatment of 1 ml metam-sodium in 100 liters nutrient solution. Measurements of yield, nutrient composition, plant survival, and runnering were taken. There was no significant difference in nutrient consumption among the treatments. There were significant differences in time to first fruit, yield, and runnering. Metam-sodium inhibited runner production. The treatment that excluded light from the nutrien solution resulted in prolific runnering and had larger fruit size.
The demand for plug transplants by the Florida winter strawberry (Fragaria ×ananassa Duch.) industry may increase as water conservation during plant establishment becomes more important and the loss of methyl bromide fumigant makes the production of bare-root transplants more problematic. A study was conducted during the 1995-96 and 1996-97 seasons to determine the effect of container size and temperature conditioning on the plant growth and early season fruit yield of `Sweet Charlie' strawberry plants. Plants in containers of three sizes (75, 150, and 300 cm3) were grown in one of two temperature-controlled greenhouses (35 °C day/25 °C night or 25 °C day/15 °C night) for the 2 weeks just prior to transplanting into a fruiting field at Dover, Fla. Plants exposed to the 25/15 °C treatment had significantly higher average root dry weights at planting in 1995 and 1996 than did plants exposed to the 35/25 °C treatment. Plants exposed to the 25/15 °C treatment also had higher average fruit yields than the plants exposed to the 35/25 °C treatment (48% and 18% higher in 1995-96 and 1996-97, respectively). The effect of container size on plant growth and yield was variable. Plants propagated in the 150- and 300-cm3 containers tended to be larger (at planting) than the plants propagated in the 75-cm3 containers, but the larger container sizes did not result in consistently higher yields.
Bare-root strawberry transplants have been conventionally used for establishment of strawberry fruiting fields. These bare-root transplants have variability in vegetative vigor that results in irregular flowering patterns. We have been experimenting with a containerized transplant system to produce uniform transplants. Increasing transplant container volume by increasing perimeter, rather than depth, has resulted in increased plant size, but also increases transplant production costs. This study evaluated three container perimeters (17, 25, 32 cm) and three container shapes (circular, elliptical, and biconvex) such that different cell perimeters had the same greatest diameter. All containers had a depth of 3.5 cm. Root imaging analysis (MacRHIZOTM) was used to measure root growth in the container as well as root growth 3 and 6 weeks after transplanting. Increasing container perimeter led to increased plant growth before and after transplanting, but did not affect fruit production. Transplant container shape did not significantly alter plant growth or fruit production. Biconvex and elliptical containers required 25% and 15% less surface area, respectively. Therefore, a biconvex shaped container can be used to increase plant density during transplant propagation, decreasing surface area needed and reducing production costs.
Containerized strawberry transplants offer an alternative to problematic bare-root transplants, which often have variability in flowering and vegetative vigor. Containerized transplants were propagated in three different container cell sizes (75, 150, and 300 cm3) and grown at two different temperature regimes for 2 weeks prior to planting (25/15 and 35/25°C day/night). Bare-root transplants from Massachusetts and Florida were graded into small, medium, and large plants based on crown size (8, 12, and 16 mm respectively). Plug transplants grown at 25/15°C had greater root dry weights than transplants grown at 35/25°C. Root imaging analysis (MacRHIZO) showed that the differences in dry weight were due to root area, not root tissue density. Crown dry weight increased with increasing cell size. Plug transplants grown at 25/15°C flowered earlier and had greater production than any other treatment. The 75 cm3 cell size grown at 35/25°C produced greater December strawberry production than larger cell sizes at the same temperature regime; however, the 75 cm3 cell size had decreased January strawberry production while the larger cell sizes had increased production. Larger plug cell sizes had significantly greater production than smaller plugs throughout the season, whereas larger bare-roots had greater production only early in the season. Containerized plug transplants therefore offers a viable alternative to problematic bare-root transplants.
A greenhouse hydroponic system, which uses suspended plastic troughs, was found to be an efficient system for the production of high quality strawberry (Fragaria ×ananassa) plantlets. In this system micropropagated mother plants of `Oso Grande' and `Sweet Charlie' produced an average of 84 and 80 daughters per mother plant, respectively, in 1996, at a plant density of 3 mother plants/ft2 (32 mother plants/m2). Nearly 100% of the plantlets harvested from the system were successfully rooted in plug trays, and showed no symptoms of leaf or crown diseases.
A seed bioassay was developed in order to elucidate the mechanism of interference in Lycopersicon hirsutum. Extracts of L. hirsutum were compared to extracts of other plant species, several of which have been determined to demonstrate allelopathic properties. Measurements of germination, root growth, and hypocotyl elongation were used as parameters for these experiments. A titration experiment was conducted to determine the concentrations needed for seed inhibition. I50 values were generated to determine the concentration needed to inhibit 50 percent of the seeds for each species. L. hirsutum possessed a significantly greater inhibition than any of the other species examined. Lettuce (Lactuca sativa) and common purslane (Portulaca oleracea) seeds provided the best response because of quick uniform germination.
Laboratory experiments were conducted to evaluate the relationship between leaf area, leaf number, dry weight, and mg extract of Lycopersicon hirsutum (LA 1777) leaf washes and germination or root growth of common purslane (Portulaca oleracea) seeds. Additional experiments were conducted to determine the relationship between L. hirsutum (accessions 1777 and 1625) leaf washes and germination or root growth of common purslane seeds. Activity of separated sesquiterpenes from trichomes were compared to crude leaf washes. Results from the leaf washes of the L. hirsutum accessions (1777 and 1625) indicated that there was no significant difference between hexane leaf washes, methanol leaf washes, or crude leaf extracts when common purslane was used as the assay species. The accession 1777 was greater than 800 x more inhibitory to germination and greater than 300x more inhibitory to root growth of purslane seeds than accession 1625.
Experiments were conducted in two seasons in Dover, Fla. (central Florida), with bare-root and containerized (plug) strawberry (Fragaria ×ananassa) transplants to evaluate transplant establishment-period water use, plant growth, and flowering responses in the 3-week transplant establishment period. Strawberry plug plants were established with 290 gal/acre water applied only with the transplant at planting time, while 200,000 gal/acre from microjet or 1 million gal/acre of water from sprinkler irrigation were used to establish bare-root transplants. Root, shoot, and crown dry matter of plug plants rapidly increased during the establishment period, while there was a decline in leaf area and root and crown mass of bare-root plants, even with sprinkler or microjet irrigation. Water applied with the bare-root transplant only at planting was not enough to keep the plant alive during the establishment period. Large plug plants, but not irrigated bare-root plants, began flowering at 3 weeks after planting. Plug plants were used to successfully establish strawberry crops with low water inputs.
Strawberry (Fragaria ×ananassa) crops were transplanted in two seasons in central Florida with bare-root and containerized (plug) plants under three transplant establishment-period irrigation methods to evaluate crop fruiting responses and production economics associated with the various establishment systems. Irrigation was not required to establish plug transplants in the field. Early (first 2 months) fruit yield with nonirrigated plug plants was greater than early yield with sprinkler-irrigated bare-root plants (the current commercial system) in one of two seasons and equal in a second season. Total-season yields were similar in each season between the two establishment systems. Large or medium plug plants led to greatest early fruit yields in one season while large plug plants resulted in greatest early yield in a second season. Total yield was greatest with medium plants in one season and large plants in another season. The extra cost for the plug plant system was $1853/acre. In one out of two seasons there was increased net income amounting to $1142/acre due to greater early yield associated with the plug plant cultural system. Strawberry plug transplants showed promise for earlier and more profitable crops in addition to substantial savings in water used for plant establishment in the field. The ability to establish strawberry crops without irrigation will be important in areas where growers are required to reduce farm water consumption.