`Sunny' tomato (Lycopersicon esculentum Mill.) seedlings were pretransplant nutritionally conditioned (PNC) in 1988 and 1989 with factorial combinations of N from 100 to 300 mg·liter-1 and P from 10 to 70 mg·liter-1. In 1988, all conditioned seedlings were exposed to 12 hours of 2C for eight consecutive nights before transplanting. In 1989, half of the conditioned plants were exposed to a low-temperature treatment of 8 days with 12-hour nights at 2C and 12-hour days in a warm greenhouse (19C/26C, night/day). In both years, as N PNC increased to 200 mg·liter-1, seedling growth increased. Increasing P PNC from 10 to 40 mg·liter-1 increased seedling growth, but only in 1988. In both years, P PNC did not affect yields. Low-temperature exposure in 1989 decreased seedling growth in comparison to those held in a warm greenhouse (19C/26C, day/night). In 1988, first harvest yields were not affected by N PNC; however, in 1989, as N increased to 200 mg·liter-1, early yields increased. In 1988, total yields increased wit h N PNC from 100 to 200 mg·liter-1 and in 1989 with N at 50 to 100 mg·liter-1 with no further increases from 100 to 200 mg·liter-1. Low-temperature exposure had no effect on earliness, yield, or quality. A PNC regime combining at least 200 mg N/liter and up to 10 mg P/liter should be used to nutritionally condition `Sunny' tomato seedlings to enhance yield.
Regina R. Melton and Robert J. Dufault
Yves Desjardins, André Gosselin, and Michel Lamarre
Asparagus (Asparagus officinalis L.) transplants and in vitro-cultured clones were grown and acclimatized under two photosynthetic photon flux (PPF) conditions (ambient and ambient + 80 μmol·s-1·m-2) and three atmospheric CO2 concentrations (330, 900, and 1500 ppm). Short- and long-term effects were measured in the greenhouse and after two seasons of growth in the field, respectively. In the greenhouse, CO2 enrichment (CE) and supplemental lighting (SL) increased root and fern dry weight by 196% and 336%, respectively, for transplants and by 335% and 229%, respectively, for clones. For these characteristics, a significant interaction was observed between SL and CE with tissue-cultured plantlets. In the absence of SL, CE did not significantly increase root or shoot dry weight. No interaction was observed between CE and SL for transplants, although these factors significantly improved growth. It was possible to reduce the nursery period by as much as 3 weeks with CE and SL and still obtain a plant size comparable to that of the control at the end of the experiment. Long-term effects of SL were observed after two seasons of growth in the field. Supplemental lighting improved survival of transplants and was particularly beneficial to in vitro plants. Clones grown under SL were of similar size as transplants after 2 years in the field.
Beny Aloni, Tamara Pashkar, Lea Karni, and Jaleh Daie
We investigated the effects of N nutrition on growth and carbohydrate partitioning of pepper (Capsicum annuum L., cv. Maor) seedlings in the greenhouse and on their subsequent recovery and development after transplanting. Seedlings received 0, 30, 100, or 200 mg N/liter for 14 days, after which they were transplanted and received 100 mg N/liter. Nitrogen levels below 100 mg·liter−1 inhibited shoot growth and leaf chlorophyll content; both were severely inhibited in the absence of supplemental N. Root growth had a negative relation with N supply; an enhanced root: shoot ratio was observed under low-N regimes. On a unit-leaf-area basis, CO2 fixation was not affected when N was present; however, it was greatly inhibited in the absence of N. Changes in the leaf starch and soluble sugar concentrations occurred as a function of N supply and leaf age. In the roots, low N led to lower sucrose and higher levels of hexose and starch. More sucrose was transported and accumulated into leaf veins of low-N tissue. Exogenously supplied 14C-labeled sucrose was rapidly converted into starch in the low-N tissue. Seedlings that received 100 mg N/liter had the highest post-transplant growth rate and flowered earlier. Carbohydrate status of young pepper seedlings influenced their post-transplant recovery. Optimal N supply is essential for full recovery and development of transplants.
Robert J. Dufault and Jonathan R. Schultheis
To reduce transplant shock of bell peppers (Capsicum annuum L.), we tested the effectiveness of pretransplant nutritional conditioning (PNC) as a promoter of earliness and yield. In Expt. 1, `Gatorbelle' bell pepper seedlings were fertilized with N from Ca(NO3)2 at 25, 75, or 225 mg·liter-1 and P from Ca(H2PO4)2 at 5, 15, or 45 mg·liter-1. Nitrogen interacted with P, affecting shoot fresh and dry weight, leaf area, root dry weight, seedling height, and leaf count. In Expt. 2, transplants conditioned with N from 50, 100, and 200 mg·liter-1 and P at 15, 30, and 60 mg·liter-1 were field-planted in Charleston, S.C., and Clinton, N.C. Nitrogen- and P-PNC did not greatly affect recovery from transplant shock. Although N- and P-PNC affected seedling growth in the greenhouse, earliness, total yield, and quality were similar in field studies among all PNC treatments at both locations. PNC with 50 mg N and 15 mg P/liter can be used with this variety and not have any long-term detrimental effects on yield and quality.
John M. Dole, Frankie L. Fanelli, William C. Fonteno, Beth Harden, and Sylvia M. Blankenship
Optimum postharvest handling procedures were determined for Dahlia `Karma Thalia', Lupinusmutabilis ssp. cruickshankii`Sunrise', Papaver nudicaule `Temptress', and Rudbeckia`Indian Summer.' Dahlia harvested fully open had a vase life of 7–10 days in deionized (DI) water that was increased by 1.5–2 days using commercial holding solutions (Chrysal Professional 2 Processing Solution or Floralife Professional). Neither floral foam nor 0.1–1.0 ppm ethylene had any effect on vase life. One week of cold storage at 1 °C reduced vase life up to 2 days. The longest vase life, 12–13 days, was obtained when floral buds, showing a minimum of 50% color, were harvested at the breaking stage (one petal open) and placed in 2% or 4% sucrose or a commercial holding solution. Lupinus flowers held in DI water lasted 8–12 days; 1 week cold storage at 1 °C reduced vase life by 3 days. Florets and buds abscised or failed to open when exposed to ethylene; STS pretreatment prevented the effects of ethylene. Commercial holding solutions increased Papaver vase life to 7–8 days from 5.5 days for stems held in DI water. While stems could be cold stored for 1 week at 1 °C with no decrease in vase life, 2 weeks of cold storage reduced vase life. Flowers were not affected by foam or ethylene. Rudbeckia had a vase life of 27–37 days and no treatments extended vase life. Stems could be stored at 2 °C for up to 2 weeks and were not ethylene sensitive. Floral foam reduced the vase life over 50%, but still resulted in a 13-day vase life.
John M. Dole, Frankie L. Fanelli, William C. Fonteno, Beth Harden, and Sylvia M. Blankenship
Optimum postharvest handling procedures were determined for Linaria maroccana `Lace Violet', Trachelium`Jemmy Royal Purple', and Zinnia elegans `Benary's Giant Scarlet' and `Sungold.' A 24-hour 10% or 20% sucrose pulse increased the vase life of Linaria by 2–4 days, resulting in a vase life of 9 days as compared to 5 days for control flowers held in deionized (DI) water. Use of floral foam and cold storage at 1 °C for 1 week decreased vase life. Treatment with either 0.1 or 1.0 ppm ethylene had no effect. The use of a commercial holding solution (Floralife Professional or Chrysal Professional 2 Processing Solution) or 2% or 3% sucrose increased vase life 4–10 days. For cut Trachelium, ethylene caused florets to close entirely or stop opening; 1-MCP and STS prevented these ethylene effects. Stems tolerated 4 days of 1 °C storage, but 1 week or more of storage reduced the 14-day vase life of unstored flowers to 9 days. Stems in 2% or 4% sucrose had a longer vase life compared to DI water. While the use of floral foam was not detrimental when used with sucrose solutions, it reduced vase life when sucrose was not used. Zinnia stems could not be cold stored for 1 week at 1 °C due to loss of turgidity and cold damage. Stems stored dry at 5 °C regained turgidity and averaged a vase life of 14 days; however, petals remained slightly twisted and curled after being in the vase for several days. Treatment with ethylene had no effect. Floral foam reduced vase life to 9–10 days.
Jonathan R. Schultheis and Robert J. Dufault
Pretransplant nutritional conditioning (PNC) of transplants during greenhouse production may improve recovery from transplanting stress and enhance earliness and yield of watermelon [Citrullus lanatus (Thumb.) Matsum. & Nakai]. Two greenhouse experiments (Expts. 1 and 2) and field experiments in South Carolina and North Carolina (Expt. 3) were conducted to evaluate N and P PNC effects on watermelon seedling growth and their effects on fruit yield and quality. `Queen of Hearts' triploid and `Crimson Sweet' diploid watermelon seedlings were fertilized with N from calcium nitrate at 25, 75, or 225 mg·liter–1 and P from calcium phosphate at 5, 15, or 45 mg·liter–1. In the greenhouse, most variation in the shoot fresh and dry weights, leaf count, leaf area, transplant height, and root dry weight in `Queen of Hearts' and `Crimson Sweet' was attributed to N. Cultivar interacted with N, affecting all seedling growth variables, but not leaf area in Expt. 2. To a lesser extent, in Expt. 1, but not in Expt. 2, P interacted with cultivar, N, or cultivar × N and affected shoot fresh and dry weights, leaf count and leaf area. In the field, transplant shock increased linearly with N, regardless of cultivar or field location. The effect of PNC on plant growth diminished as the growing season progressed. For both cultivars at both locations, N and P PNC did not affect time to first staminate flower, fruit set, fruit width or length, soluble solids concentration, or yield. Vining at Charleston for both cultivars was 2 days earlier when N was at 75 rather than 25 mg·liter–1, without further change with the high N rate. At Clinton, the first pistillate flower was delayed linearly the higher the N rate for `Crimson Sweet'. At Charleston, hollow heart in the `Queen of Hearts' increased nearly 3 times when N PNC rate was tripled (from 75 or 225 mg·liter–1), while N had no effect on hollow heart in `Crimson Sweet'. In contrast, at Clinton, hollow heart in either cultivar was affected by P PNC, not N. PNC with 25N–5P (in mg·liter–1) can be used to reduce seedling growth and produce a more compact plant for easier handling, yet not reduce fruit quality or yield.
Meng Li, Huanhuan Zhi, and Yu Dong
GB, or 4 g·L −1 GB. All treatments were applied three times: at pit hardening (20 May for ‘Lapins’; 23 May for ‘Regina’); straw color (9 June for ‘Lapins’; 12 June for ‘Regina’); and 1WBH (5 July for ‘Lapins’; 12 July for ‘Regina’). Fruit quality
Ann M. Callahan, Chris Dardick, and Ralph Scorza
) hardening via lignification does not effectively take place in ‘Stoneless’, leaving regions where the endocarp layer is present but does not harden or 2) incomplete endocarp formation that results in fragmented stones. Materials and Methods Plant
Fatih Ali Canli, Murat Sahin, Nurettin Temurtas, and Mustafa Pektas
and Resnizky, 1988 ; Usenik et al., 2005 )]. The synthetic auxin 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) improved color and size of apricot when it was applied during the pit hardening phase ( Bregoli et al., 2010 ). A preharvest spray of