Interest in grape juice has risen as the public becomes more aware of natural foods and the specific evidence of healthful benefits of grapes. Among major preharvest conditions that influence quality of grape juice are climate, soil, cultivar, vineyard management, and maturity. Each of these factors exerts its own influence, but complex interactions among these factors must be recognized. For mechanically harvested juice grapes, cultivar takes on special importance to quality and yield as do the production system, harvest machines, postharvest handling systems, and processing method. Grape juice composition has been extensively studied, and production and processing methods have improved over the years. The following discussion deals with developments in grape juice production.
Justin R. Morris
Troy A. Larsen* and Christopher S. Cramer
Current onion varieties that are grown in New Mexico were developed for hand harvesting and not for mechanical harvesting. In order for onion production in New Mexico to remain a viable commodity, firmer onion varieties need to be developed for mechanical harvesting. In this study, bulb firmness of onions was examined in short and intermediate-day onion entries comparing a qualitative `finger pressure' method with a digital FFF-series durometer. After harvesting and curing of the onion bulbs, dry outer scales were removed before durometer measurements were taken at two perpendicular points on the vertical center axis of the bulb. Following the durometer measurements, bulb firmness was rated by `finger pressure' applied to multiple points on the vertical center axis. For intermediate and late-maturing entries, durometer measurements and firmness rating were positively correlated in a strong fashion (r = 0.77 to 0.87). Early maturing entries, NMSU 02-25 and NMSU 02-03 both had high durometer averages and firmness ratings. `NuMex Crimson' and `NuMex Crispy' had the highest durometer averages and firmness ratings among intermediate maturing entries while `NuMex Solano' and NMSU 01-06 had the highest among late maturing entries. From our results, the durometer can be useful in providing a quantifiable measure of bulb firmness.
Our efforts are concentrated on quantifying spatial variability for tree vigor, yield, fruit quality, and profit. We use aerial photography to quantify tree vigor. For mechanically harvested hazelnuts, a prototype weight based yield monitor has been evaluated. This approach may also work for quantifying yield in mechanically harvested sweet cherries. For perishable hand-harvested crops, the GPS locations for individual bar-coded bins can be used to calculate bin density and estimate yield. Bar codes can also be used to track quality in the packing-house. Since profit depends on yield, size, and packout, it is not always intuitively obvious which areas of an orchard are most profitable. Defining which areas are most profitable, and identifying the problems associated with low-profit areas (poor yield, small size, storage loss, bruising, culls, etc) is an important step. Identifying areas producing fruit that stores poorly is a high priority. An evaluation of low- and high-profit areas may lead to alternate management plans. Anything from investing in more supervision of harvest labor and initiating different pruning regimes to attempts to obtain more uniform tree vigor can be evaluated. By delineating test areas with GPS boundaries, profit data in future years can quantify the success of different management approaches. For example, concentrating expensive inputs on the portion of trees (30% of total) that may produce the majority of gross returns, while not even harvesting fruit from regions (1% to 5% of total) that consistently produce poor quality fruit may be a sound strategy.
Gregory E. Welbaum
Seed production in the family Cucurbitaceae is more complicated than in dry-seeded grain crops because seeds mature within a moist fruit and are often held at high moisture content for several weeks before seed harvest. Muskmelon (Cucumis melo L.), a member of this family, was used as a model system to contrast seed development with crops that are dry at maturity. A detailed time course for `Top Mark' fruit and seed development is presented based on previous studies. In muskmelon fruit, precocious germination is inhibited osmotically by the low water potential of the surrounding fruit tissue. Muskmelon seeds exhibit primary dormancy that affects viability very early in development but has a greater effect on seed vigor and is removed by afterripening during dry storage. Osmotically distended or fish-mouth seeds are dead seeds that occur in cucurbit seed lots after aging kills the embryo without disrupting the semipermeable endosperm that completely surrounds and protects the embryo. Cucurbit seed crops should be harvested before the onset of fruit senescence to prevent aging of the seeds inside. Open-pollinated cucurbit seed crops are frequently once-over mechanically harvested. Mechanical harvesting combines seeds from many stages of development into a single seed lot, which may adversely affect quality and increase seed to seed variability. Hand harvesting cucurbit fruit at the optimal stage of development could improve seed quality in some instances but is more costly and time consuming and would increase production costs.
Three different types of pickling cucumber (Cucumis sativus) were planted in the field with 4 replications in a randomized complete block design. The cultivars selected were standard leaf, “little leaf”, and standard X “little leaf” crosses. The growth of populations of cucumber fruit from each of the three types was measured over a 14 day period which included the optimum harvest date for mechanically harvesting the fruit. A plant sample one m2was randomly selected, the population of fruit diameter and length in each sample was measured daily. The standard leaf types were the first to reach a harvest date. The standard X “little leaf” crosses were next, followed by the “little leaf” cultivar. The differences in days to harvest could be 14 days or more between the standard and “little leaf types. The distribution of fruit by number and volume will be presented. Using this information a harvest date for maximum economic return can be predicted for each of the cultivars.
Ursula K. Schuch, Leslie H. Fuchigami and Mike A. Nagao
Unsynchronized flowering and fruit ripening of coffee prohibits mechanical harvesting and results in high labor costs. Coffee (C.arabica c. Guatemalan) trees were sprayed at the beginning of the 1988 and 1989 flowering season with solutions of benzyladenine (BA), gibberellic acid GA3 (GA), and Promalin (PR) or were pruned in 1988 to determine effects on synchronizing flowering and ripening. Growth regulators affected the time to flowering and harvesting compared to the control, however, treatment effects were dependent on the time of growth regulator application. Application of PR and GA at 100 mg/l in Jan 1988 shortened the average days to flowering by 16 and 13 days, and the average days to harvest by 15 days compared to the control. Pruning of three apical nodes of primary lateral branches in Feb 1988 caused delays in flowering, reduced flower and fruit number per tree, and caused branch dieback.
The extent of translocation of 14C-labeled photosynthates from the senescent leaf to the parent vine before leaf abscission and the short-term effects of premature leaf removal on the carbohydrate balance of the vine were studied by using autoradiography and trapping 14CO2 respired from the treated leaf. The treated leaf abscissed 1.5 days after administering the label. The plant was harvested after natural leaf abscission. The radioactivity recovered from the plant, excluding the treated leaf, was 20% of the input. Radioactivity was detected in the roots, trunk, shoot, and leaves. Most of the radioactivity remained in the trunk and the young and old roots. The implications of premature leaf removal by mechanical harvesting on the carbohydrate balance of the vine are discussed.
The wild lowbush blueberry (Vaccinium angustifolium) in Maine and the Maritime Provinces of Canada has been managed for hundreds of years, first by native Americans and more recently by European settlers. Early production practices consisted of periodic free burns over large tracts of land for pruning and weed control. New practices have centered on intensifying production and include flail mow pruning, mechanical harvesting, herbicides for weed control, and monitoring pest populations. Most recently, land smoothing for improved mechanization and leaf sampling for nutrient analysis have been adopted. Land smoothing allows producers with rough land to use labor-saving equipment and apply pesticides more precisely. Leaf analysis predicts nutrient availability much more accurately than soil testing.
JALORO is a multiple virus resistant (MVR) open pollinated pepper cultivar developed by Texas Agricultural Experiment Station at Weslaco. This pungent, cylindrical (fruit with blunt end) yellow jalapeño cultivar possesses high levels of resistance to several isolates of Texas tobacco etch virus, potato virus Y, pepper mottle virus, tobacco ringspot virus, cucumber mosaic virus and tobacco mosaic virus. The genotype combines desirable characteristics of commercial hot yellow wax `Caloro'(TMR), the jalapeño genome from `Jalapeño-L' and Jalapeño 1158, and MVR genes from AC2207 (hot serrano) and PI 264280. `Jaloro' has the ability to set fruit at temperatures above 35C. It has a concentrated flower setting habit, sets fruits earlier and matures more uniformly than `Caloro'. The singlestem plant will support a heavy set of large thick yellow jalapeño fruit which can be mechanically harvested. It is suited for fresh market in salads or as a processed product, pickled whole, sliced as `nacho' rings or diced in picante sauces.
Mario Mandujano, F.G. Dennis Jr., D.E. Guyer, E. Timm and G.K. Brown
Michigan growers often have severe problems with soft `Montmorency' sour cherries. Causal factors may include weather conditions, orchard practices, harvesting methods, and conditions during hold of fruits prior to processing. In this study, efforts were concentrated on orchard practices, including shading to reduce solar radiation, irrigation, nutrient level, and application of growth regulators, especially ethephon and gibberellin. Fruit firmness decreased as maturity approached, then stabilized. Significant fruit softening occurred only during mechanical harvesting. No treatments, including sprays of calcium and potassium, consistently increased firmness, but firmness was reduced in 1993 by spraying with ethephon. Firmness varied among orchards, but no “soft” fruit, as defined by industry standards, were observed in harvested fruit. Softening appeared to be caused by excessive bruising, and was always associated with mechanical damage. Advanced maturity and heavy cropping appear to predispose the cherries to greater bruise damage.