Brushing 2-week-old `Sunny' tomato (Lycopersicon esculentum Mill.) seedlings, grown in a commercial production greenhouse, for a period of 5 weeks reduced transplant growth and improved plant appearance. Brushing reduced stem length 37% and leaf area 31% relative to nontreated control plants. Plants were darker green in color, stockier, easier to handle, and tougher (exhibited less breakage) than nontreated plants.
A brushing system for vegetable transplants that is adjustable, easy to use, and provides uniform brushing action was designed and constructed. Using this system, the height of several species and cultivars of vegetable transplants was reduced 15% to 50%. Quality and uniformity also were improved, and edge effects on growth were reduced.
Many shoot sampling variables were found to influence bud rest of apple (Malus domestica Borkh.). Unlike terminal buds, uppermost lateral buds on decapitated stem pieces were stimulated by wounding and developed throughout the rest period under forcing conditions in a growth chamber and their rate of development was an accurate measure of depth of rest. Neither segment length nor location on the original intact shoot affected bud rest intensity, but single-node segments were avoided because they became desiccated. Rate of development of resting buds in darkness increased with increasing temperature between 20° and 30°C. Bud rest intensity decreased with decreasing shoot length. Shoot location in the tree crown (shaded interior vs. exterior) did not affect bud rest intensity, but there was a significant interaction between crop load and shoot height in the tree. Many interactions were significant between various shoot characteristics and bud rest intensity. Spurs were compared to shoots on the basis of the percent of a population showing terminal budbreak after 28 days of forcing. Terminal buds on spurs entered rest later and emerged earlier than did terminal buds on short, medium or long shoots.
Pot-grown seedlings of seven lines [`Red Cherry' (RC), `Moneymaker' (MM), `Dantobi-yohzu' (DY), `Furikoma' (FK), RC × FK, MM × DY, and MM × FK] of tomato (Lycopersicon esculentum Mill.) were brushed with a suspended steel bar for 1.5 minutes twice daily for 18 days (short-term treatment) before being transplanted to beds in a plastic greenhouse. Brushing was continued on a selected group of plants for an additional 10 days (long-term treatment). Short-term brushing slightly reduced the number of leaves, but markedly reduced leaf size and stem elongation of all lines. Dry weights of lamina, petioles, and stems of brushed plants of each cultivar except FK were less than those of the respective controls. However, the ratios of root: shoot dry weight of brushed plants were unchanged or higher than those of the respective controls. Short-term brushing did not increase the total number or weight of tomato fruits harvested over 1 month and did not improve fruit quality, size, or color. Long-term brushing reduced the total yield (number and weight) of fruits of RC and total fruit weight of DY. With respect to sensitivity to mechanical stress, cultivars with taller growth habits were more responsive to brushing than were those with shorter growth habits. These characteristic responses to mechanical stress also were exhibited by the hybrid lines.
Shoots of field-grown plants of European radish (Raphanus sativus L. `Comet'), Japanese radish (daikon) (R. sativus L. `Mino-wase'), and Asian turnip (Brassica rapa L. `Hinona') were brushed twice daily, 40 cycles (back-and-forth strokes equal one cycle), for 8 (short-term) or 13, 21, or 14 days (long-term), respectively. European turnip (B. rapa L. `Hikari-kabu') plants were grown in a raised bed in an uncovered plastic house and were brushed for 9 or 21 days. Short-term brushing reduced root dry weight and the root: shoot dry weight ratio (R: S) of European radish, whereas the treatment increased these measurements for Asian turnip and European turnip. Short-term brushing had no effect on growth of Japanese radish plants, but increased root dry weight gain by both turnip cultivars, thereby increasing their R: S ratios. Lung-term brushing reduced root dry weight gain and the R: S ratio of European radish and root dry weight of Asian turnip but had no effect on these measurements for the other crops. Long-term brushing reduced cracking of European radish roots, thereby resulting in a higher proportion of oblong (medium quality) roots. Consequently, the percentage of marketable-quality roots of European radish was increased by brushing. Lung-term brushing increased the percentage of medium-sized roots of Asian turnip at the expense of large-sized roots. Brushing had no effect on root quality of European turnip.
Ethephon [(2-chloroethyl) phosphonic acid] is widely used as a growth regulator in floricultural crop production, with foliar sprays as the typical application method. Ethephon efficacy is determined by rate of uptake and subsequent ethylene evolution, which can be influenced by a number of factors, including solution pH. This study examines whether an ethephon substrate drench (100 mg⋅L−1 at a volume of 296 mL per 2.8-L container) would allow for plant uptake in two herbaceous perennials, Verbena bonariensis (L.) ‘Lollipop’ and Veronica spicata (L.) ‘Goodness Grows’, as measured by subsequent effects on shoot growth and days to flower. We also investigated substrate pH effects on ethephon drench efficacy by analyzing the shoot responses to ethephon applied at a range of starting substrate pH (4.5 to 7.0) compared with untreated plants grown under the same substrate pH conditions (controls). One or more measurements of shoot growth (height, width, shoot dry weight) were reduced in both taxa treated with ethephon as compared with controls. Veronica plant growth was not influenced by substrate pH in either the control or ethephon-drenched plants. For Verbena plants receiving the ethephon drench, as substrate pH increased, height and width increased. For example, when ethephon was applied at substrate pH 4.5, finished plant height averaged 32.0 cm, compared with 43.5 cm for those plants that received the drench at a substrate pH of 7.0. Increasing substrate pH conditions also influenced the days to flower in Verbena plants. Ethephon-treated plants at a substrate pH of 4.5 required an average of 6.5 days longer to flower than those at a substrate pH of 7.0. In summary, ethephon drench applications can result in significant growth regulation effects, as seen in both Veronica and Verbena. Furthermore, increasing substrate pH can reduce the efficacy of ethephon drench applications.
The influence of two fungicides—captan and thiram—on growth and 45Ca absorption by roots of `Starbrite' watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] seedlings was investigated. Unilateral application of Ca+2 and Al in agar induced curvature in roots from untreated and pretreated seeds. In untreated seeds, PCMBS inhibited Ca+2- and Al-induced root curvature by 82% and 92%, respectively. In commercially pretreated seeds (captan + thiram), PCMBS inhibited Ca+2- but not Al-induced root curvature. Captan or thiram also inhibited Ca+2- or Al-induced root curvature, and the effects of captan and thiram on root curvature were additive. Serial concentration (0, 0.01, 0.1, 1, 10, or 100 mg·liter-1) tests indicated that captan inhibited 45Ca absorption the most at 100 mg·liter-1, whereas thiram inhibited 45Ca absorption the most at 0.01 mg·liter-1. The effects of captan and thiram on 45Ca absorption were statistically additive. Thiram seemed to influence Ca+2 uptake by affecting exofacial sulfhydryl groups (a mode of action similar to that of PCMBS). DTT reversed the inhibitory effect of thiram on 45Ca absorption by 34% but did not reverse the effect of captan. A field test showed that acidic soil (pH 4.55) reduced leaf number; leaf, stem, shoot, and whole-plant dry weights; and stem length of 15-day-old seedlings. Although there was no difference in root dry weights or root: shoot ratios of plants from pretreated and untreated seeds planted in soil at pH 6.26, planting commercially pretreated seeds in acidic soil produced plants with greater root dry weights and root: shoot dry weight ratios than those from untreated seeds. Seedlings showed a greater response to seed treatment in early growth stages. Captan and thiram may have influenced growth characteristics by inhibiting Al uptake of seedlings planted in acidic soil. To our knowledge, this is the first report on the influence of the fungicides captan and thiram on mineral ion uptake in roots. Chemical names used: p-Chloromercuribenzenesulfonic acid (PCMBS), dithiothreitol (DTT), N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide (captan), tetramethylthiuram disulfide (thiram).
Eggplant (Solanum melongena L. var. esculentum ‘Burpee's Black Beauty’) and soybean [Glycine max (L.) Merr. ‘Wells II’] seedlings were assigned to a greenhouse or a windless or windy outdoor environment. Plants within each environment received either periodic seismic (shaking) or thigmic (flexing or rubbing) treatments, or were left undisturbed. Productivity (dry weight) and dimensional (leaf area and stem length) growth parameters generally were reduced more by mechanical stress in the greenhouse (soybean) or outdoor-windless environment (eggplant) than in the outdoor windy environment. Outdoor exposure enhanced both stem and leaf specific weights, whereas mechanical stress enhanced only leaf specific weight. Although both forms of controlled mechanical stress tended to reduce node and internode diameters of soybean, outdoor exposure increased stem diameter.
A survey was conducted in 2000-01 to provide a comprehensive description of Virginia's commercial greenhouse industry. A total of 274 responses were analyzed. Responses were categorized based on the amount of heated greenhouse space: small, medium, large, or other (including part-time). The survey included questions about growing space, number of employees, education and experience of respondent, crops grown, gross receipts, and target markets. Seventy-five percent of the respondents were owners or owners/growers and respondents reported an average of 15 years experience. Most greenhouse operations were classified as small or less than 10,000 ft2 (929.0 m2). A wide variety of crops were reported, with more than 50% growing bedding plants and nearly 50% growing herbaceous perennials in the greenhouse. Market outlets were about equally divided between wholesale and retail.