A nondestructive method for measuring the soluble solids (SS) content of peaches [Prunus persica (L.) Batsch] was developed using near-infrared (NIR) spectrometry. NIR transmittance in the 800 to 1050 nm region was measured for four cultivars of peaches (`Blake', `Encore', `Red Haven', and `Winblo'), over a period of three seasons (1993 through 1995). Each fruit was scanned on both halves keeping the suture away from the incident light beam. Soluble solids contents of flesh samples taken from corresponding scanned areas were determined using a refractometer. Multiple linear regression models using two wavelengths were developed with second derivative spectral data and laboratory measurements of SS content. Multiple correlation coefficients (R) for individual cultivar calibrations within a single season ranged from 0.76 to 0.98 with standard error of calibration (SEC) values from 0.35% to 1.22%. Selected spectra and corresponding SS data in individual cultivar calibration data sets were combined to create season and cultivar calibration data sets to cover the entire range of SS contents within the season or within the cultivar. These combined calibrations resulted in R values of 0.92 to 0.97 with SEC values ranging from 0.37% to 0.79%. Simple correlations of validations (r) ranged from 0.20 to 0.94 and the standard error of prediction (SEP) ranged from 0.49% to 1.63% while the bias varied from -0.01% to -2.62%. Lower r values and higher SEP and bias values resulted when individual cultivar calibrations were used to predict SS levels in other cultivar validation data sets. Cultivar calibrations, season calibrations and the overall calibration predicted SS content of all validation data sets with a smaller bias and SEP and with higher r values. These results indicate that NIR spectrometry is suitable for rapid nondestructive determination of SS in peaches. Feasible applications of the method include packinghouse sorting of peaches for sweetness and parent and progeny fruit quality assessment in peach breeding programs. Using this technique fruit may be sorted into two or three sweetness classes. The technique may also potentially be extended to other fruit.
México is an important producer of mangos for exportation. Losses occurring during postharvest due to poor handling practices, spoilage and injury during transportation reduces the quality of the fruit for shipment overseas. A hot water immersion treatment of 46C for 90 min and film wrapping of the fruit were studied to evaluate losses that occur during the sorting and packing of the fruit for market abroad. Cultivars of mangos included in the study were Tomy Atkins, Hayden, Kent, and Keitt. Fruits were selected from different points in the packing line before and after the hot water treatment and were stored at 10C and 20C for 30 days. Additionally, fruits were divided in subgroups and packed individually in low density polyethylene bags. Fruits were evaluated every 10 days for color, weight, firmness and injuries. Most severe losses occurred when the fruits were selected later in the packing line. Hot water treatment caused severe discoloration on the fruits. Film packing decreased weight loss, improved firmness, and retarded ripening and onset of spoilage.
Exogenous application of ethanol (EtOH) vapor to whole tomato fruit or excised pericarp discs inhibits ripening without affecting subsequent quality. Inhibitory EtOH levels are induced in whole tomatoes by a 72 h exposure to anaerobic atmospheres at 20C. In contrast to tomatoes, exposure to EtOH vapor (0 to 6 ml EtOH/kg FW, for 3 to 6 h at 20C) did not retard ripening (e.g., changes in external color, flesh firmness, and soluble solids) of avocado, banana, cucumber, melon, peach, or plum fruit. When the blocked replicates for nectarines were sorted by the firmness of the control fruit, higher levels of EtOH vapor appeared to delay softening of the firmer fruit. From 0 to 4 ml EtOH/kg FW was injected as 95% EtOH into the seed cavity of melon fruit through a surface sterilized area near the equator of the fruit with a plastic syringe fitted with a 7.5 cm long hypodermic needle. Injection of 1 to 4 ml EtOH/kg FW inhibited the softening of `Honey Dew' and muskmelons. Slight tissue necrosis near the site of injection was noted in a few fruit. Unlike the ripening inhibition of tomatoes which is relatively insensitive to the stage of maturity, the inhibition of melon ripening by EtOH appeared to be significantly affected by the maturity of the fruit.
The National Plant Germplasm System (NPGS) is a network of federal and state cooperative agencies which houses germplasm of economically important crops and their wild relatives. Curators are assigned to coordinate long term collections at facilities located throughout the country for optimum crop performance. Constant awareness of germplasm outside of the NPGS system will improve the scope and value of NPGS collections. This alternate source germplasm can reside in other national germplasm collections, in breeding and research collections, in botanical gardens and arboreta, and with private companies, organizations, or individuals. New plant explorations also continue to provide additional germplasm. Many organizations and individuals have begun compiling and publishing lists of germplasm sources. A summary of lists for temperate fruit and nut germplasm will be presented as an example. Compilations of this sort are extremely useful at the time of publishing but become outdated as listed sources change, or new sources are established. Periodic updating of published compilations are thus required. Contacts with Crop Advisory Committee members, plant researchers, and professional and amateur specialist organizations are also important sources of germplasm information.
A series of video clips and narrated PowerPoints were developed to aid in the presentation of common horticultural techniques. To determine the most effective format for delivery of horticultural subject matter, video clips and PowerPoints were developed for three topic areas and presented to two target audience groups. Target audiences consisted of Master Gardeners (Orange and Osceola County, Fla.) and future horticulture professionals (UF Environmental Horticulture students enrolled in Landscape Plant Establishment). Upon completion of viewing both media formats, participants were asked to complete a survey. Eighty-six percent of participants completed and returned surveys. Data were sorted and analyzed for calculation of mean percent for each response sought. Results of the survey indicated that, depending upon the topic, a higher proportion (66% to 93%) of Master Gardeners preferred narrated PowerPoints in comparison to video clips. However, 60% to 70% of students preferred video clips to narrated PowerPoints. In reference to the informative nature of both videos and PowerPoints, >67% of all respondents rated both media formats between good and excellent; however, most respondents indicated new information gained was less than 40%. Factoring the costs associated with production (about $1000 per video vs. essentially no cost for narrated PowerPoints) and participant responses, narrated PowerPoints appear the best option for conveying common horticultural practices.
Sorbitol (d-glucitol) is the major end product of photosynthesis in apple (Malus domestica Borkh.), as well as the predominant phloem-translocated carbohydrate. The mechanism by which sorbitol is phloem-loaded for transport to heterotrophic sink tissues is unknown. We hypothesized that a plasma membrane-bound H+/sorbitol symporter mediates apoplastic phloem-loading of sorbitol. To discover genes potentially encoding sorbitol transporters, a cDNA library was constructed from mature `Gala' apple leaves. A homologous probe was synthesized via PCR with primers were designed against the cherry fruit sorbitol transporter, PcSot1, and using library lysate as template. From an initial plating of approximately 5 × 105 clones, twelve positives were identified after three rounds of hybridization screening. Following single-pass, 5' end sequencing, the clones were sorted into four contiguous sequences. One clone was chosen from each contig for complete sequencing. The four clones, provisionally named MdSOT1-4 (Malus domesitca Sorbitol Transporter), potentially encode full-length cDNAs for sorbitol transporters: Translated-BLAST searching (blastx) revealed that the open reading frames encode the complete Pfam sugar transporter domain, and the most significant alignments are with sequences encoding known- and putative polyol and sugar transporters.
Warm daytime and cool nighttime temperatures during fruit maturation are conducive to anthocyanin synthesis and starch degradation in many apple cultivars. In parts of the world, high temperatures during fruit maturation result in sunburn of varying degrees of severity ranging from slight bleaching of the pigments in the epidermal layer to cracked and desiccated skin. This experiment assessed the effects of sunburn on fruit quality and mineral nutrition at harvest. In September 1990, about 2000 `Granny Smith' or `Delicious' apples were examined for sunburn and sorted into the following categories: none, light, bleached, bronzed, buckskin, and cracked. Twenty fruit were collected for each category. Each fruit was subdivided into exposed and shaded halves. Each half of each fruit was evaluated for firmness, soluble solids, and acidity. Tissue samples were analyzed for sugars, total nitrogen, and mineral content. Data suggest that excessive heat due to solar radiation creates a gradient of sugars and minerals within the fruit resulting in increased disorders in certain areas of the fruit.
Industrial-scale cultivation of plant cells for valuable product recovery (e.g. natural pigments, pharmaceutical compounds) can only be considered commercially-feasible when a fully-automated, predictable bioprocess is achieved. Automation of cell selection, quantification, and sorting procedures, and pinpointing of optimal microenvironmental regimes can be approached via machine vision. Macroscopic staging of Ajuga reptans callus masses (ranging between 2-6 g FW) permitted simultaneous rapid capture of top and side views. Area data used in a linear regression model yielded a reliable, non-destructive estimate of fresh mass. Suspension culture images from the same cell line were microscopically imaged at 4x (with an inverted microscope). Using color machine vision, the HSI (hue-saturation-intensity) coordinates were used to successfully separate pigmented cells and aggregates from non-pigmented cells, aggregates, and background debris. Time-course sampling of a routine suspension culture consistently allowed pigmented cells to be detected, and intensity could be correlated with the degree of pigmentation as verified using spectrophotometer analysis of parallel samples.
Interrelations between water potential and fruit size, crop load, and stomatal conductance were studied in drip-irrigated `Spadona' pear (Pyrus communis L) grafted on quince C (Cydonia oblonga L.) rootstock and growing in a semi-arid zone. Five irrigation rates were applied in the main fruit growth phase: rates of 0.25, 0.40, 0.60, 0.80, and 1.00 of “Class A” pan evaporation rate. The crop in each irrigation treatment was adjusted to four levels (200 to 1200 fruit per tree) by hand thinning at the beginning of June 1999. The crop was harvested on 1 Aug. 1999, and fruit size was determined by means of a commercial sorting machine. Soil, stem, and leaf water potentials and stomatal conductance were measured during the season. Crop yield was highly correlated with stem and soil water potentials. The highest midday stem water potential was lower than values commonly reported for nonstressed trees, and was accompanied by high soil water potential, indicating that the maximal water absorption rate of the root system under those particular soil conditions was limited. Stomatal conductance was highly correlated with leaf water potential (r 2 = 0.54), but a much better correlation was found with stem water potential (r 2 = 0.80). Stomatal conductance decreased at stem water potentials less than -2.1 MPa. Both stem water potential and stomatal conductance were unaffected by crop load under a wide range of irrigation rates.