increasing the cost of production ( Dewir et al., 2014 ; Gao et al., 2017a ; Hazarika, 2006 ; Kozai et al., 1997 ). In this study, the effects of calcium nitrate on the reversion of hyperhydric banana ‘Grand Naine’, a commercially important dessert banana
M.E. El-Mahrouk, A.R. El-Shereif, Y.H. Dewir, Y.M. Hafez, Kh. A. Abdelaal, S. El-Hendawy, H. Migdadi and R.S. Al-Obeed
Caroline H. Pearson-Mims and Virginia I. Lohr
Cut `Samantha' roses (Rosa hybrida L.) were placed in deionized water or a 20-mm Ca(NO3)2 pulsing solution for 72 hours. Flowers then were held in preservative solutions containing 0 or 4 mg fluoride/liter. Fresh weight gain, solution uptake, degree of flower opening, and flower longevity were reduced in the presence of fluoride in the holding solution. Visual symptoms of injury and reduced flower quality also were noted in treatments with fluoride. Pulsing improved fresh weight gain and degree of opening of flowers held in solutions containing fluoride. Pulsing also delayed the onset of visual symptoms of fluoride injury. Water uptake for flowers that were pulsed and exposed to fluoride was not different from uptake for flowers exposed to fluoride alone. Flower longevity for roses in all treatments was increased by using the calcium nitrate pulse, but pulsed flowers in fluoride did not survive as long as the control flowers.
Chiwon W. Lee, Keun Ho Cho, Larry J. Cihacek and Robert W. Stack
The influence of calcium nitrate fertilization on the storage characteristics of carrot (Daucus carota) roots was investigated. Plants of `Navajo' carrots grown under irrigation were sprayed with a 2% solution of Ca(NO3)2 4H2O at a rate of 50 kg/ha Ca 10 days before harvest. Quality of carrot roots stored at 5 °C was evaluated monthly for sweetness, tissue electrolyte leakage, disease development and visual characteristics. For disease development, the crown portion of the carrot roots was inoculated with an ascospore solution (2 × 109 spores/mL) of white mold (Sclerotinia sclerotiorum) before storage. When determined after 1 month of storage, percent tissue electrolyte leakage in the Ca-treated carrots decreased 52% as compared to that obtained from the control. Sugar contents of the cortex and xylem tissues were not affected by calcium nitrate fertilization. Changes in other quality parameters of carrot roots for an extended storage period, including white mold development, will be presented. Initial findings of this research suggest that foliar calcium feeding at the final stage of plant growth may enhance the quality of carrot roots during storage.
Lisa Grishow and Alejandro Ching
Some studies have shown that the presence of calcium ions greatly influence the growth of lateral shoots in poinsettia. Rooted cuttins were transplanted in 13.14 cm dia. plastic pots and grown on Metro-mix soil, fertilized with 20-10-S osmocote and watered as needed. Plants were sprayed with 300 & 600 ppm of ca(NO3)2. Others treated with 500 ppm of 6-BA, plus 300 and 600 ppm of Ca(NO3)2 and then with 500 ppn of 6-BA. Some plants were left without treatments as check. The average number of lateral bud breaks were highest on plants treated with 6-BA when compared to plants treated only with Ca(NO3)2 and the check. The number of lateral bud breaks increased from an average of 11 on the 5th day to 15 on the 30th day whenever 6-BA was applied. The average length of lateral shoots also increased from an average of 10mm the 5th day to over 23mn on the 30th day when 6-BA was applied, but the presence of Ca(NO3)2 at 300 ppm lateral shoot growth was greater than at 600 ppm. In general, the average growth rate in height increased in all treatments compared to the check and the presence of Ca(NO3)2 further increased the growth in height. Finally, the foliage growth rate (in diameter) was greatly influenced by 6-BA and 600 ppm of Ca(NO3)2.
`Newtown' apples (Malus domestics Borkh.) treated weekly with urea at 10 g·liter-l or Ca(NO3)2 at 7.5 g·liter-1 for 5 consecutive weeks from late August were greener at harvest and during storage than comparable control fruit. A postharvest dip in Nutri-Save, a polymeric coating, was better for retention of skin greenness than a dip in diphenylamine and both gave greener apples than control (nondipped) fruit. Fruit treated with Ca(NO3)2 displayed lesions that were larger and more numerous than typical bitter pit in the control fruit.
Apostolos A. Paralikas, J.C. Vlahos, M. Papadimitriou and K.A. Loulakakis
Ebenus cretica, Leguminosae, an endemic perennial bush of Crete, is being studied as a potential new cut flower crop. Forty-centimeter-long spikes with two to three inflorescences and six to eight compound leaves were harvested from 5-year-old plants grown from seed at the farm of the TEI, when 1/3 of the florets had opened, and were treated with various preservatives. Flower quality was evaluated morphologically combined with measurements of chlorophyll content in leaves and anthocyanin in petals. Without any postharvest treatments, inflorescences held in a solution of 100 ppm 8-hydroxyquinone sulfate (HQS) in DI water had an average vaselife of 6.8 days. Pulsing with 0.6 mM silver thiosulfate (STS) for 2 h extended vaselife up to 8.4 days. However, when ethephon was added in the solution, vaselife was significantly reduced, causing leaf yellowing and flower senescence, which suggests sensitivity to exogenous ethylene. A solution of 0.2% Ca(NO3)2 prolonged vaselife by 2.7 days, whereas higher concentrations resulted in flower discoloration and decreased flower quality. Sucrose solutions of 0.5%, 1%, 2%, and 4% had no positive effect on flower longevity. Furthermore, the higher concentrations caused leaf yellowing and petal discoloration decreasing vaselife and quality of flowers compared to control. Samples of inflorescences were taken every second day for chlorophyll (a and b) and anthocyanin measurements. The concentrations recorded were highest in the 0.2% Ca(NO3)2 treatment and were significantly correlated to flower longevity. Results indicate that Ebenus cretica may be used as a cut flower crop; however, due to the genetic variability of the Ebenus plants, a breeding line should be developed before the crop reaches the floricultural market.
Charles S. Vavrina, Thomas A. Obreza and John Cornell
`Tropical Quick' Chinese cabbage (Brassica rapa L., Pekinensis Group) was planted three times at 2-week intervals in Spring 1991 (direct-seeded) and two times in Fall 1991 (transplanted) in double rows on polyethylene-mulched beds to evaluate N source and rates. Calcium nitrate, ammonium nitrate, urea, urea-ammonium nitrate solution (Uran), and urea-calcium solution (Nitro-Pius) were applied preplant at 67,112, and 157 kg N/ha. The two later spring planting dates, compared with the earliest date, resulted in greater head fresh weights and higher insect damage incidence, but lower tipburn and flowering incidence. The earlier fall planting resulted in greater head fresh weight but a much higher flowering incidence than the later planting. Irrespective of planting date, head fresh weight increased quadratically, and tipburn and flowering incidence decreased linearly with increasing N rate. Although N source affected head fresh weight and tipbum incidence, differences were too small to be of practical value.
J.L. Walworth, D.E. Carling and G.J. Michaelson
Head lettuce (Lactuca sativa L.) cv. Salinas was produced in field trials in southcentral Alaska with varying planting dates, planting methods, N sources, and N application rates. Variables measured included head weight and diameter and harvest date. Nitrogen source had little effect on head weight. Direct-seeded lettuce produced heaviest beads from early plantings; transplants produced heaviest heads when planted in mid- to late season. Transplanting generally produced heavier heads than direct-seeding. Head weight of transplanted and direct-seeded lettuce was maximized with ≈112 kg N/ha. The data suggest that 112 kg N/ha may be suitable for lettuce direct-seeded or transplanted throughout the growing season.
M.D. Taylor, S.J. Locascio and M.R. Alligood
`Equinox' tomatoes (Lycopersicon esculentum Mill.) were grown during the springs of 2001 and 2002 with black polyethylene-mulch and drip irrigation on an Arredondo fine sand in Gainesville, Fla., to study the influence of water quantity, Ca source, and reduced K on incidence of blossom-end rot (BER), marketable fruit yield, and fruit and leaf Ca concentration. Tensiometers were used to schedule irrigation in main plots when the soil matric potential reached 10 or 25 kPa. Subplot nutritional treatments were no added Ca, Ca(NO3)2, Ca thiosulfate, CaCl2, CaSO4, and K rate reduced by 50%. Interactions between year and treatment were significant. During 2001, total marketable yields were higher with Ca(NO3)2 or CaCl2 compared to plants that received Ca thiosulfate and were higher from plants irrigated at 10 kPa than irrigated at 25 kPa. Number and weight of BER fruit were lower with Ca(NO3)2 and reduced K than with no added Ca and CaSO4. Leaf and fruit Ca concentrations were generally higher with Ca(NO3)2 compared to all other nutritional treatments. Leaf and fruit Ca concentrations were generally higher from plants irrigated at 10 kPa than at 25 kPa. The reduction of NH4 +-N, by the supply of N as NO3 -, and the addition of supplemental Ca reduced the incidence of BER, and increased the leaf and fruit Ca concentrations. During 2002, marketable yields were higher with CaSO4 than with CaCl2 and reduced K. Weight and number of BER fruit were lower with irrigation at 10 kPa than at 25 kPa. Leaf and fruit Ca concentrations were higher or similar from plants that received Ca(NO3)2 than with all other nutritional treatments. During the 2002 season, rainfall was less and temperatures and daily evapotranspiration (ET) were higher than in the 2001 season. In the 2002 season, 3.28 × 106 L·ha-1 of irrigation was applied as compared to 1.58 × 106 L·ha-1 in 2001. With an average Ca concentration of 76 mg·L-1 in the irrigation water, much more Ca was applied during the higher ET 2002 season. With the higher transpiration and temperature, water uptake and hence, Ca uptake were increased. During both seasons, the lowest Ca concentration was observed at the blossom end of the fruit and the highest Ca at the stem end of the fruit. Fruit Ca concentrations were lower and BER was 5 times higher in the lower ET, higher rainfall (lower irrigation) 2001 season compared to the higher ET, lower rainfall (higher irrigation) 2002 season. These data support that BER was a symptom of Ca deficiency and this deficiency was aggravated by high rainfall, low ET, and the resulting reduced irrigation applied and reduced Ca uptake.
J.M. Quintana, H.C. Harrison, J.P. Palta, J. Nienhuis and K. Kmiecik
To measure the effect of added Ca fertilizer on the Ca concentration of snap bean pods, four snap bean cultivars were grown during Summer 1996 and 1997 at Hancock, Wis. Fertilizer treatments consisted of 80 kg of Ca per hectare applied as Ca sulfate (CaSO4·2H2O) or Ca nitrate [Ca(NO3)2], and the control (no Ca applied. The experimental design was a randomized complete block with a factorial set of treatments (4 × 3). Calcium sulfate was applied at planting, whereas Ca nitrate was split applied four times at weekly intervals starting 1 week before flowering. Yield and Ca concentration in pods were determined. The statistical analysis showed no significant effect of Ca fertilizers on pod Ca concentration or yield. A strong cultivar effect was detected for both parameters measured. `Evergreen' (5.47 mg Ca per gram dry weight) had the highest pod Ca concentration and `Labrador' (4.10 mg Ca per gram dry weight) the lowest. No significant fertilizer × cultivar interactions were observed. Results for pod Ca concentration remained consistent, even when significant year effects were found for both parameters.