Commercially processed citrus seeds of Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L) Raf.], Swingle citrumelo (C. paradisi Macf. × P. trifoliata), Cleopatra mandarin (C. reticulate Blanco), and sour orange (C. aurantium L.) were used to test the effects of grading, hydrating, and priming on the rate of germination and seedling emergence. Sorting seed into groups by fresh weight or diameter did not generally improve seed performance. Seed fresh weight was highly correlated with maximum seed diameter; also, large seed weight and size were associated with a larger number of embryos. When seedlings from the extra embryos were removed, large seed produced the largest seedlings. Soaking seeds in aerated water significantly increased germination and emergence rates over unsoaked seeds. Soaking at 35C rather than 25C enhanced these differences. Priming seeds in one of three solutions of polyethylene glycol 6000 (—0.6 to—1.2 Mpa) was not successful> as germination and emergence Per centages were lower than in distilled water.
A rapid nondestructive method for measuring apple texture using sonic vibrational characteristics of intact apples was tested on freshly harvested `Delicious' apples from major U.S. production areas. Sonic transmission spectra and Magness-Taylor (MT) firmness were measured on whole apples and compression measurements were made on excised tissue. Two experienced Agricultural Marketing Service apple inspectors assessed each apple and assigned a ripeness score according to U.S. Dept. of Agriculture grades and standards inspection procedures (based primarily on texture). Sonic functions correlated significantly with ripeness scores, MT firmness, and forces to rupture or crush the tissue in compression. Ripeness scores were more closely correlated with the destructive firmness measurements than with sonic functions. However, sonic measurement has the advantage of being nondestructive, whereas MT and tissue compression are inherently destructive. Further research is needed to modify the Instrumentation and Sensing Laboratory`s sonic technique to improve the prediction of apple firmness before it can be adapted for on-line sorting.
Samples of 16 cranberry (Vaccinium macrocarpon Ait.) clones, sorted into subsamples on the basis of berry size and coloration, were analyzed for juice content, soluble solids, titratable acidity, and anthocyanin content. The soluble solids : acidity ratio was greater for more highly colored subsamples but did not vary with berry size. The anthocyanin content of subsamples of different berry size varied in proportion to the surface to volume ratio. Anthocyanin recovery in expressed juice was independent of berry coloration and size. Variability in anthocyanin content within samples reflected differences in environmental factors, such as light exposure, superimposed on ripeness differences. Variability in sample anthocyanin content depended more on berry size differences than on differences in surface coloration.
Fruit from 7- and 8-year-old ‘Tifblue’ rabbiteye blueberry [Vaccinium ashei (Reade)] plants were harvested at 0600, 0900, 1200, and 1500 hr. Harvests occurred twice a season for each of 2 years. Fruit cullage after machine harvesting averaged ≈30% of total fruit harvested. The first machine harvest in a season had 6% to 16% less cullage than the last harvest. The number of mature fruit remaining on the plants after harvesting decreased with later harvest times during the day. Thus, an increase in harvester efficiency corresponded to decreased leaf water potential. The effect of harvest time during the day on packout and fruit quality after storage was inconsistent between and within years. There was no optimum time of day to machine-pick blueberries when fruit were promptly sorted and cooled after harvest.
Fruits of ‘Cardinal’ and A-5344 strawberries (Fragaria X ananassa Duch.) were once-over harvested and sorted into 5 maturity categories: immature green, mature green, inception, firm ripe, and processing ripe. Purees of each maturity were characterized for their potential contribution to the quality of puree obtained from a once-over strawberry harvest. As the berry matured, weight, percent soluble solids, ascorbic acid, and water-soluble pectins increased. Total solids, acidity, total phenols, puree viscosity, cellulose, protopectin, peroxidase activity (PO), and polyphenol oxidase (PPO) activity decreased with increasing fruit maturity. Presence of chlorophyll, lack of anthocyanins, higher total phenols, and PO and PPO activity found in the green fruits could be potentially detrimental to puree quality. Higher puree viscosity which resulted from higher cellulose and protopectin levels and lower water-soluble pectins in the green berries would be beneficial to strawberry puree quality.
The North Carolina Cooperative Extension Service's New Hanover County Center provides the Plant Disease and Insect Clinic staffed by the Horticulture Extension Agent and Master Gardener volunteers. Residents bring in samples of weeds, diseases, and insects for identification and control recommendations. After the problem is diagnosed, a record of the information is used to construct a database that includes the date, phone number, crop, diagnosis, and control for each sample submitted. Between January 1993 and December 1999, Master Gardener volunteers entered more than 4,000 entries into a searchable/sortable electronic database to identify patterns of plant disorders. The database should be a useful tool for predicting local disease and insect cycles and aiding Master Gardeners in answering questions at the clinic and over the telephone. In addition, examination of historical records and entry of data into the database are excellent learning opportunities for new Master Gardeners.
Maturity at harvest determines seed viability and vigor. However, separating seeds from different stages of development can be difficult using existing seed sorting technologies. New technology non-destructively sorts seeds based on their chlorophyll fluorescence (CF), so seeds with the same dry weight but with different physiological maturates can be separated. We determined whether chlorophyll content of muskmelon (Cucumis melo L. cv. Top Mark) seeds changes during development and whether those changes were related to viability and vigor. Seed viability and vigor were determined using an Association of Official Seed Analysts wet paper towel germination test. `Top Mark' seeds from nine stages of development were run through the SeedMaster Analyzer (Satake USA Inc., Houston, Texas), which calculated the chlorophyll content of each seed. The CF signal was fed into a computer to obtain a frequency histogram. Forty, 45, and 55 days after anthesis (DAA) seeds had germination percentages of 96%, 98%, and 100%, respectively, the highest in the study. Fifty-five DAA had greater seed vigor and viability and contained the lowest CF values; 207 on the 1000-value scale. The less-mature seeds contained higher chlorophyll content and had the lowest seed vigor and viability. Seed vigor and chlorophyll content were negatively correlated in this study. All seeds with high CF values had low vigor, but not all seeds with low CF values have high vigor. Seed aging during storage can reduce viability and vigor independent of chlorophyll content. Based on chlorophyll content, the SeedMaster Analyzer can non-destructively remove immature, low-vigor seeds that have the same physical characteristics and weight as more mature seeds. Chlorophyll fluorescence technology may allow the seed industry to further improve seed quality and maximize vigor.
Replicated trials were conducted in summers of 1998 and 1999 at two commercial orchards (A and B) to determine the influence of a metalized, high-density polyethylene reflective film (SonocoRF, Sonoco Products Co., Hartsville, S.C.) and ReTain (Abbott Laboratories, Inc., N. Chicago, Ill.), on fruit red skin color and maturity of `Gala' apples. There were four experimental treatments: i) Control; ii) Reflective Film (RF); iii) ReTain; and iv) RF + ReTain. RF was laid 4 weeks before anticipated first pick date by laying a 5-ft-wide strip of plastic on either side of the tree row in the middle. ReTain was applied 4 weeks before harvest at the commercial rate in one orchard (A) and at 60% the commercial rate in the other orchard (B). At harvest, two 50-fruit samples were picked from each of four replicate blocks per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for puncture pressure, soluble solids concentration (SSC) and starch hydrolysis. ReTain delayed maturity and reduced preharvest drop of `Gala'. Fruit from RF trees had a significantly greater percent red surface than fruit from trees not treated with RF. Fruit from RF + ReTain were significantly redder and had higher SSC than fruits from trees treated with ReTain alone. There were no differences in size, puncture pressure or starch hydrolysis between RF and RF + ReTain. RF appears to be a means to ensure greater redness in `Gala' treated with ReTain in South Carolina.
Replicated trials were conducted in summers of 1998 and 1999 at several commercial orchards to determine the influence of a metalized, high-density polyethylene reflective film (SonocoRF, Sonoco Products Co., Hartsville, S.C.) on fruit red skin color and maturity of peach cultivars that historically have poor red coloration in South Carolina. At each site there were two experimental treatments: i) Control; and ii) Reflective Film (RF). RF was laid 2 to 4 weeks before anticipated first pick date by laying a 5-ft-wide strip of plastic on either side of the tree row in the middles. Treatment blocks at a given farm ranged from 0.5 to 1 acre in size and each treatment was replicated four times at each site. At harvest, two 50-fruit samples were picked from each block per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for puncture pressure and soluble solids concentration (SSC). All cultivars tested (CVN1, Loring, Bounty, Summer Gold, Sun Prince, Cresthaven, and Encore) experienced significant increases in percent red surface when RF was used in 1998 and 1999. This color improvement ranged from 16 to 44% (mean = 28%). On average, fruits from RF were 0.8 lb softer and had 0.3% higher SSC than control fruits. Growers harvested more fruit earlier and in fewer picks for RF. Fruit size was not affected by RF. The influence of RF on orchard microclimate and quality and quantity of reflected light will be discussed.
Replicated trials were conducted during the summers of 1998 and 1999 at commercial orchards in South Carolina to determine the influence of ground application of a metalized, high density polyethylene reflective film on fruit red skin color and maturity of peach (Prunus persica) cultivars that historically have poor red coloration. At each site there were two experimental treatments: 1) control and 2) reflective film (film). Film was applied 2 to 4 weeks before anticipated first harvest date by laying a 150-cm (5-ft) wide strip of plastic on either side of the tree row in the middles. Treatment areas at a given farm ranged from 0.25 to 0.5 ha (0.5 to 1.0 acre) in size and each treatment was replicated four times at each site. At harvest, two 50-fruit samples were picked from each plot per treatment. All fruit were sized and visually sorted for color (1 = 0% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100% red surface, respectively). A 10-fruit subsample was selected following color sorting and evaluated for firmness and soluble solids concentration (SSC). All cultivars tested (`CVN1', `Loring', `Bounty', `Summer Gold', `Sunprince', `Cresthaven' and `Encore') experienced significant increases in percent red surface when film was used in 1998 and 1999. This color improvement ranged from 16% to 44% (mean = 28%). On average, fruit from film were 4.2 N (0.9 lb force) softer and had 0.3% higher SSC than control fruit. Growers harvested more fruit earlier and in fewer harvests for film. Fruit size was not affected by film. Reflected solar radiation from film was not different in quality than incident sunlight. Film resulted in an increase in canopy air temperature and a reduction in canopy relative humidity during daylight hours.