Testing Potential Alternate Methods of Bloom Thinning for Apple in Vitro (original) (raw)
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HortScience
A strategy of chemical crop load control has been to use chemical desiccants to prevent fertilization and cause fruitlet drop. However, little is known of the solution characteristics that reduce pollen viability, inhibit pollen germination and growth, and cause pistil damage. This project was established to determine the solution characteristics effecting those results. Apple pollen was dispersed on germination media mixed with PEG (MW 10,000) to attain osmotic tensions from 0 to -5.0 MPa to evaluate effect on pollen germination and growth. Similarly, apple pollen was dispersed on germination adjusted to a range of pH from 2.3 to 12.0 with acids and NaOH. Excised apple pistils were place on filter paper supports saturated with solutions with osmotic tension adjusted by PEG in the range of 0 to -5.0 M Pa, and pH from 3.0 to 12.0. Solutions of osmotic tension in the range of 0 to -5.0 M Pa were applied by brush to intact pistils on apple flowers in a greenhouse and under field condit...
HortScience, 2009
Effects of temperature and the combination of liquid lime sulfur (LLS) and fish oil (FO) applied during bloom on pollen germination and pollen tube growth in flowers and fruit set were examined in apples (Malus ×domestica Borkh.). Percent germination of pollen of ‘Manchurian’ crabapples and ‘Golden Delicious’ apple flowers on the stigmatic surface of ‘Golden Delicious’ pistils increased with increasing temperature from 13 to 29 °C in the first 24 and 48 h after pollination, respectively, but not thereafter. Pollen tube growth rate in the style increased quadratically with increasing temperature from 13 to 29 °C. ‘Manchurian’ was a more effective pollenizer of ‘Golden Delicious’ than was ‘Golden Delicious’ pollen. For example, at 24 or 29 °C, some ‘Manchurian’ pollen tubes grew to the base of ‘Golden Delicious’ styles by 24 h after pollination. On the other hand, no ‘Golden Delicious’ pollen tube grew to the base of a ‘Golden Delicious’ style regardless of temperature and time. Polle...
HortScience, 1999
Leaf impressions were made from two short-lived (4 and 5 d) inbreds, a longlived (11 d) inbred, and their hybrids (8 and 9 d) of Antirrhinum majus L. using Super Glue and glass microscope slides. Leaves were taken from mid stem, pressed on glass slides (under side down), spread with a small amount of Super Glue, set for 3 to 4 s. Then, the leaf was peeled off leaving a permanent impression in the glue. Slides were placed under a microscope equipped with a video imaging A phenol-sulfuric acid assay was used to quantify non-specific neutral carbohydrates in Antirrhinum majus L. flowering stems of three inbreds and their hybrids. Flowering stems 40 cm long were harvested with five to six florets open and flower, leaf, and stem tissue separated, freeze-dried, and finely ground. Carbohydrates were extracted from the tissue with 95% ethanol in a 70 °C water bath and combined with a 5% w/v phenol solution and concentrated sulfuric acid. Glucose equivalents were determined with a spectrophotometer at absorbance of 490 nm. Averaged over tissue type, results were genotype dependent, ranging from 213 to 291 µg glucose equivalent per mg dry tissue with a LSD 0.05 = 13. Flowers had the highest concentration of 340 µg/mg dry tissue, followed by stems, then leaves with 36% and 38% lower concentrations, respectively. Carbohydrate concentrations in two inbreds were compared when grown under cool (16 °C) and warm (29 °C) conditions. A genotype x environment interaction exists with inbred 3 exhibiting no reduction, 6% increase, and a 45% reduction in carbohydrate concentration when grown in warm conditions, while inbred 2 exhibited 15%, 23%, and 37 % reductions for flowers, leaves, and stems, respectively. Overall, there were 10% and 21% reductions in carbohydrate concentration for inbreds 2 and 3, respectively, when plants were grown under warm conditions. In an effort to determine the optimal light level for growing pawpaw [ Asimina triloba (L.) Dunal] seedlings outside, seedlings were germinated in a greenhouse until the two-to three-leaf stage, at which time they were placed outside and shade treatments were imposed that reduced incident light intensity by 30%, 55%, 80%, and 95%. Control seedlings were left unshaded outside. A randomized block design was used, with 20 replicate seedlings in each experimental treatment per block. Plants were destructively harvested 11 weeks after the start of the experiment. After 11 weeks, the height and number of leaves per seedling were about 35% higher with light to moderate shading (30%, 55%, and 80%) than in control (unshaded) seedlings. Shoot and leaf dry weights of seedlings grown in 30%, 55%, and 80% shade were almost 2-fold greater than control plants. Root dry weight of seedlings in 30% and 55% shade was 2-fold higher than in control plants. Total plant biomass was greatest in the 30%, 55%, and 80% shade treatments, about 2-fold higher than control plants. Total leaf area per seedling increased significantly with up to 80% shading. Seedlings growing under 95% shading had fewer and smaller leaves and reduced biomass production compared to control plants. There was a trend for shaded plants to display a higher leaf chlorophyll content than control plants. Overall, the best seedling growth was achieved in the 30% and 55% shade treatments outdoors. Lettuce (Lactuca sativa) is one of the most important U.S. fresh-market vegetables with year-round consumption. For winter markets, lettuce is produced in the southwestern states with plantings in early fall when soil temperatures are high. Seed germination of lettuce, however, is inhibited by soil temperatures over Echinacea pallida, one of the three medicinal Echinacea species native to North America, is generally wildcrafted, and low and uneven seed germination are obstacles to its widespread cultivation. Nonstratified E. pallida seeds were treated with 2500, 3500, and 4500 mg/L GA 3 to increase seed germination. Treated seeds were directly germinated at 25 °C and 25/15 °C (14/10h) or stored at 5 and 10 °C for 4, 8, and 12 weeks before germination at the same temperatures. Seed germination across treatments was higher at 25 °C (19%) than at 25/15 °C (14%). Application of 2500, 3500, and 4500 mg/L GA 3 significantly increased seed germination rate and total seed germination of nonstratified seeds of E. pallida and resulted in 44%, 50%, and 63% total seed germination, respectively, while untreated control seeds germinated at only 9%. The effect of GA 3 as a germination stimulant increased with cold storage, with maximum germination (83%) occurring after seeds were treated with 4500 mg/L GA 3 and an 8-week cold storage period at 10 °C. The effect of cold storage periods of 4, 8, and 12 weeks and cold storage temperatures of 5 and 10 °C on seed germination were generally similar. Seeds collected from the upper rows of the seed heads germinated significantly higher (10.6%) than those collected from the lowest seed rows (2.4%). Recent advances in technology have made the snapdragon, Antirrhinum majus L., a promising florist crop in North America and potentially on the Ontario market. CO 2 is a known inhibitor of ethylene action, but its effects tend to be difficult to interpret based on the variable responses of plants to this gas. Recently, a gaseous ethylene analog has been shown to inhibit certain ethylene responses of cut flowers, such as wilting in carnations and flower abscission of cut phlox. This cyclic olefin, 1-methylcyclopropene (1-MCP), is thought to bind irreversibly to the ethylene receptor sites, thereby preventing or delaying ethylene responses. In the experiments undertaken, the potential of CO 2 and 1-MCP were investigated for their ability to enhance vase life and to reduce shattering and wilting of snapdragons. Flowers were sealed in ≈0.2-m 3 chambers encased in 6-mil polyethylene and exposed to elevated CO 2 (5% or 10%) or 1-MCP (20-200 nL/L) for 6 to 24 h at 20 °C. The flowers were then exposed to continuous ethylene of 0-20 µL/ L. Following exposure to 5 or 20 µL/L ethylene, 1-MCP reduced shattering ≈2to 3-fold compared to CO 2 treatment. 1-MCP did not prevent the wilting response but delayed it by ≈2 days. CO 2 -treated flowers exhibited a more rapid decline in net percent open florets from days 3 to 5 post-treatment. Despite the ability of 1-MCP to reduce shattering, in the absence of exposure to continuous ethylene, it has limited effectiveness on wilting compared to CO 2 . Many consumers do not buy peaches due to the fuzzy skin and seed stone and because out-of-season peaches do not possess optimum tree-ripe flavor. The feasibility of using a non-browning freestone peach to deliver high-quality fresh-cut products was investigated. Changes in fresh-cut flavor, texture, and postharvest attributes of commercial-ripe (CR) vs. tree-ripe (TR) harvested and shipped 'Bounty' peach was assessed. Fresh-cut CR wedges had an initial firmness of 20.9 N, whereas TR wedges had 11.2 N. On day 2, firmness decreased roughly 3% to 12% and 35% to 45% for CR and TR wedges held at 1 °C, respectively. By day 5, CR wedges hardened (24.5 N) whereas TR did not return to their initial firmness; increasing marginally through day 7. Sensory panel hardness for CR did not change through storage, but with TR wedges, hardness decreased through day 2 then increased until day 7. Little variation was noted in the initial soluble solids for CR vs. TR wedges (11.7, vs. 11.4 °Brix, respectively). After 7 days storage, °Brix decreased 7.5% to 12% in CR and 4.5% to 12% in TR wedges. Yellow flesh color (b*) decreased in all CR and TR treatments through storage.
Effects of Osmotic Agents on Apple Pollen Grain Germination
HortScience
Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pisti...
Apple Disease Control and Bloom-Thinning Effects by Lime Sulfur, Regalia, and JMS Stylet-Oil
Plant Health Progress
Apple (Malus × domestica Borkh.) growers require management practices that will produce high-quality fruit while minimizing the number of chemicals used for adequate disease control and horticultural practices. Certain chemicals applied for bloom thinning also have fungicidal properties and could provide protection against early season diseases in addition to crop reduction. Over 5 years, treatments of lime sulfur (LS), Regalia (an organically approved biofungicide), and JMS Stylet-Oil (JSO) were evaluated for protection against apple scab (Venturia inaequalis [Cooke.] G. Wint.), powdery mildew (Podosphaera leucotricha [Ellis & Everh.] E. S. Salmon), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein.), and quince rust (Gymnosporangium clavipes [Cooke & Peck] Cooke & Peck in Peck), as well as crop load reduction and fruit finish. Both LS and Regalia reduced apple scab and cedar apple rust in four out of five test years. Treatments of Regalia applied with JSO provided dis...
Optimization of Apple Pollen Culture and Its Maintenance of Pollen Germination Capacity
Temperate fruits including pome fruits, especially apple are important fruit crops which mostly for fruit set needs the pollination of flowers and followed by pistil fertilization. Therefore, to achieve this act, pollen viability and its germination capability is essential. For that reason, test of pollen viability and understand its quality is important. By the same token, test to optimize the pollen medium of apple and determination best medium for it with 16 types of culture medium containing different concentrations of boric acid (0 and 100mg/1), ...
Emirates Journal of Food and Agriculture, 2017
Three concentrations of NAA (0, 10, 15 and 20 µl•l-1) were studied at three application timings (flower, fruit and the combination of each other) in order to evaluate the thinning effect on physico-chemical attributes of apple cv. Braeburn. NAA concentration was more significant factor than timing in terms of fruit production. The number and yield of fruits over 70 mm in diameter significantly increased in all application timings within all concentrations of thinner as compared to control. Thinning at 15 µl•l-1 in flower application appeared the best. The highest share of fruits over 70 mm was acquired using 20 µl•l-1 NAA in fruit application timing. The untreated trees yielded highest total number of fruits with maximum total yield efficiency and total yield efficiency in terms of number of fruits. NAA at 15 µl•l-1 increased the yield efficiency in terms of number of fruits over 70 mm and yield efficiency in terms of yield of fruits over 70 mm in diameter. Significant differences were found regarding the effects of NAA concentration and combination of both timing and concentration while timing alone showed non-significant results for SSC, TA, SSC/TA and starch. NAA at 20 µl•l-1 resulted in highest fruit firmness, SSC and TA in fruit application time. The highest levels of SSC/TA and starch degradation level were recorded with NAA at 15 µl•l-1 sprayed in combination of flower and fruit applications. Comparatively, application of 10 µl•l-1 NAA at both flower and fruit application timing is recommended to achieve best results.
Storage of apple pollen and in vitro germination
African Journal of Agricultural Research, 2011
Temperate fruits including pome fruits, especially apple are important fruit crops which mostly for fruit set needs the pollination of flowers and followed by pistil fertilization. Therefore, pollen viability and its germination capability are essential. For that reason, examination to optimize the pollen medium of apple and determination of the best medium was carried out with 16 types of culture medium containing different concentrations of boric acid (0 and 100 mg/1), calcium nitrate (0 and 300 mg/l), magnesium sulphate (0 and 200 mg/l), potassium nitrate (0 and 100 mg/l), sucrose (15%) and agar (1%) in the In vitro using random complete design with three replications. The results showed that maximum germination was in combination medium B2M1K1C2S (100 mg/l boric acid, 0mg/l sulphate magnesium, 0.0 mg/l potassium nitrate, 300 mg/l calcium nitrate, 15% sucrose and 1% agar) with 100%, and lowest germination medium in combination B1M2K2C1S (0.0 mg/l boric acid, 100 mg/l potassium nitrate, 200 mg/l magnesium sulphate, 0 mg/l calcium nitrate, 15% sucrose and 1% agar with 13.30% occurred. The viability of pollen of 4 apple cultivars, three and seven months after maintenance at 3 temperatures (4°C,-20°C and-80°C) showed that 3 months after storage, maximum germination was in Primgold Pollen stored at-80°C with 96.21% and the lowest germination (58.33%) in Northern Spy pollen stored at 4°C, but 7 months after storage, maximum germination was in Primgold Pollen stored at-80°C with 90.66% and the lowest germination (36.67%) in Northern Spy pollen stored at 4°C.
Alternate Thinning Chemicals for Apples
Acta Horticulturae
The removal of excess or unwanted flowers and/or fruit from trees is one of the most important orchard practices in pome fruit production, ensuring regular cropping and good fruit quality. Increased environmental and public health concerns have led to the banning or phasing out of many thinning chemicals and has encouraged the development and introduction of non-persistent chemicals with low toxicity levels. Many desiccating chemicals have been trialled but most have been unsuccessful because of lack of thinning at low concentrations and phytotoxic side effects at higher concentrations. However, new alternatives show potential. Two trials examined the potential of lime sulphur, fish emulsion, fish oil, potassium bicarbonate and sodium chloride as blossom thinners under Australian conditions. Lime sulphur reduced crop load in 'Gala' apples by 40%. Addition of an adjuvant increased the thinning effect up to 80%, depending on the adjuvant. Fruit size and shape were also improved where significant thinning was achieved. A combination of fish emulsion and fish oil reduced crop load by 70%, but fish emulsion combined with Tween 20 had no thinning effect. All fish emulsion treatments resulted in fruit russet. Ecocarb (potassium bicarbonate, Organic Crop Protectants, Australia) resulted in similar thinning levels to ammonium thiosulphate, reducing crop load of 'Jonagold' by 50% when applied as a 2% solution with a wetting agent. However a higher concentration of 5% Ecocarb resulted in over-thinning. Sodium chloride applied at either 2 or 5% resulted in over-thinning. Neither Ecocarb nor sodium chloride caused any fruit russeting.