Fumiomi Takeda

Cellulase activity and ethylene in ripening strawberry and apple fruits

Abstract A six-fold increase in cellulase activity, measured as the reduction in viscosity of carboxymethyl cellulose, was associated with maturation and softening in strawberry fruit. Applied ethylene did not increase cellulase levels in harvested strawberry fruit. This agrees with earlier findings that ethylene does not appear to regulate strawberry ripening. In apple, an ethylene-sensitive fruit, a decrease in cellulase activity was observed in fruit allowed to ripen on the tree.

Mechanistic approach to phytoremediation of water

Conventional thinking regarding the use of food crops to clean aquaculture effluents has been that plants cannot remove nutrients in water to low levels without a reduction in productivity and quality. Because greenhouse space is expensive, productivity is critical for a profitable operation. A production strategy, called the conveyor production system (CPS), was developed using thin-film technology for plant production in dilute aquaculture effluents. With the CPS, young plants were positioned near the solution inlet in a gutter receiving the effluent and moved progressively, like along a conveyor belt, towards the outlet as they grew. Luxury consumption by lettuce plants (Lactuca sativa L. cv. Ostinata) enabled them to store P in their tissues early in their growth cycle for use later as water P levels decreased and influx could no longer meet current demands. If water is distributed in a horizontal plug-flow pattern, without the CPS, all nutrients will be luxury consumed at the inlet, making nutrients limiting at the outlet and significant greenhouse space will be dedicated to growing plants that have no market value. The object of this study was to construct and operate a pilot-scale CPS, collect data demonstrating its potential to clean effluent and produce a marketable product, and develop a mechanistic model describing the process. Greenhouse studies demonstrated that by using the CPS, phosphorus could be reduced from 0.52 to <0.01 mg l−1 by lettuce without an apparent reduction in production or quality. The mechanistic model described in this paper simulated experimental data collected during the operation of the CPS growing lettuce and defines critical data necessary for the general comparison of effluents for treatment.

The effect of nitrogen on stolon and ramet growth in four genotypes of Fragaria chiloensis L.

Plant foraging response is a process in which clonal plants proliferate in nutrient-rich sites by shortening stolon length and increasing ramet density. Conversely, stolon length increases and ramet density decreases in nutrient-poor sites. Four genotypes of strawberry (Fragaria chiloensis (L.) Duch.) were grown in a greenhouse for 10 weeks and treated with different concentrations of nitrogen. Genotypes differed in plant size, stolon and ramet production, and nitrogen distribution between parent and ramets. Genotype Q18 were the smallest plants with the greatest number of stolons and ramets, typical of the phalanx morphology. The other genotypes had fewer but longer stolons, typical of the guerrilla morphology. Number of stolons and ramet density increased with increased N more in Genotype Q18 than the other genotypes. Results indicate that vegetative growth changed in response to increasing N treatment of the parent plant by shortening the average stolon length, increasing the number of stolons, and increasing the number of ramets while maintaining total stolon length. Foraging response characteristics were observed in strawberry but varied among genotypes.

Nondestructive Detection and Quantification of Blueberry Bruising using Near-infrared (NIR) Hyperspectral Reflectance Imaging.

Currently, blueberry bruising is evaluated by either human visual/tactile inspection or firmness measurement instruments. These methods are destructive, time-consuming, and subjective. The goal of this paper was to develop a non-destructive approach for blueberry bruising detection and quantification. Experiments were conducted on 300 samples of southern highbush blueberry (Camellia, Rebel, and Star) and on 1500 samples of northern highbush blueberry (Bluecrop, Jersey, and Liberty) for hyperspectral imaging analysis, firmness measurement, and human evaluation. An algorithm was developed to automatically calculate a bruise ratio index (ratio of bruised to whole fruit area) for bruise quantification. The spectra of bruised and healthy tissues were statistically separated and the separation was independent of cultivars. Support vector machine (SVM) classification of the spectra from the regions of interest (ROIs) achieved over 94%, 92%, and 96% accuracy on the training set, independent testing set, and combined set, respectively. The statistical results showed that the bruise ratio index was equivalent to the measured firmness but better than the predicted firmness in regard to effectiveness of bruise quantification, and the bruise ratio index had a strong correlation with human assessment (R2 = 0.78 − 0.83). Therefore, the proposed approach and the bruise ratio index are effective to non-destructively detect and quantify blueberry bruising.

ECONOMIC EVALUATION OF IMPROVED MECHANICAL HARVESTING SYSTEMS FOR EASTERN THORNLESS BLACKBERRIES

Three blackberry production systems which combine a mechanical harvester employing a new shaking principle with open trellis designs (V-, Y-, and rotatable Y-trellises) were evaluated to determine profit potential. Given a single cultivar planting of 4.7 ha and current fresh-market prices, all three machine harvest systems are profitable. When compared to a hand-harvested I-trellis, fresh-market packouts of from 72 to 132% of total yield would be required for the machine harvesting systems to have equal profitability. The relative profitability of the I-trellis, however, is very sensitive to increases in hand-harvest cost and decreases in fresh-market price. A 20% fall in price would reduce breakeven packout for the mechanical harvester to 27 to 70%. A

Use of low-dose UV-C irradiation to control powdery mildew caused by Podosphaera aphanis on strawberry plants

0.30/kg increase in hand harvest cost would reduce breakeven packout to 29 to 73%. The machine-harvesting systems are profitable under a greater range of price and yields than the I-trellis. Machine-harvesting systems are profitable at prices as low as

Method to reduce low temperature stress (LTS) in red raspberry ( Rubus idaeus L.)

0.48 to

Blueberry Producers’ Attitudes toward Harvest Mechanization for Fresh Market

0.67/kg, while hand-harvesting systems need prices of at least

Lateral Cane Lengths Affect Yield Components in ‘Triple Crown’ Blackberry on Rotating Cross-Arm Trellis and Cane Training System

1.42 to

UV-C irradiation as a management tool for Tetranychus urticae on strawberries: UV-C management for T. urticae

1.55/kg to cover costs. Machine-harvesting systems are profitable at yields as low as 13 to 31% of expected yield for fresh market, while hand-harvesting systems need yields of 44 to 49% to breakeven. Low harvest cost indicates that machine-harvesting systems would also be profitable for processing growers. Hand-harvesting systems are not profitable under current processing prices.