Rapid posttransplant root growth is often a determining component of successful establishment. This study tested the effect of transplant timing on first-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrigerated storage (F-S), or harvested and planted in the spring (S-S). All trees were transplanted into 51-L containers, adapted with root observation windows. Root growth began in F-F and F-S trees 1-2 weeks before spring budbreak, but was delayed in S-S trees until ≈3 weeks after budbreak. Budbreak was 6 days earlier for fall-harvested than for spring-harvested trees. No new roots were observed before spring. Root length accumulation against observation windows (RL) was delayed for S-S trees, but rate of increase was similar to F-F and F-S trees soon after growth began. Seasonal height, trunk diameter growth, and RL were similar among treatments. Surface area of two-dimensional pictures of entire rootballs was not correlated with seasonal RL.
J. Roger Harris, Richard Smith, and Jody Fanelli
Thomas E. Marler and Haluk M. Discekici
The influence of partial root volume irrigation on water relations and expansion of roots and leaves of papaya plants was determined using split root containers. In one study, `Tainung #1' and Solo #8 seedling roots were trained into four compartments until well-established, then water was withheld from 0, 1, 2, or 3 quadrants. Mid-morning stomatal conductance and predawn relative leaf water content were not affected by the irrigation treatments. Similarly, relative root water content in the dry quadrants was not different from that in the watered quadrants. In a second study, `Red Lady' seedling roots were trained into four compartments which contained a 13 × 13-cm plexiglass observation window. After the plants were well-established, watering was continued in one of 4 (1:4) or four of four (4:4) quadrants. Leaf midrib and root extension were measured at 06:00 and 18:00 hr each day. Daily growth of roots in the dry quadrants was reduced 25% below that in the watered quadrants, and midrib extension of the 1:4 plants was reduced ≈10% below that of the 4:4 plants. Irrigation treatments did not influence the percentage of growth occurring during the diurnal and nocturnal periods. The dry quadrants of 1:4 plants were almost devoid of fine roots. The number of root tips on the observation windows of the 1:4 plants was reduced 43% in the dry quadrants and increased 22% in the wet quadrant compared with that for the 4:4 plants.
James W. Rushing
Mature-green tomatoes stored up to 8 weeks at 11.5°C under 4% oxygen with no accumulation of carbon dioxide above ambient had reached turning stage of color by the end of the storage period. Control tomatoes stored at identical temperature without CA quickly turned red and were unmarketable after 4 weeks due to overripenessand high incidence of decay. Tomatoes held under CA for 8 weeks and then transferred to 20°C without CA ripened normally to full-red color within 10 days with less than 10% decay and no apparent mealiness or other symptoms of chilling injury. Weight loss from tomatoes stored under CA increased with storage time, but, after 8 weeks, the fruit still did not have noticeable shrivelling and visual appearance was excellent compared to tomatoes purchased from a local supermarket. Results of this research suggest that short-term CA storage is a feasible method of expanding the market window for tomatoes. This could be particularly useful for production regions such as South Carolina, where the harvest is practically completed within a 3-week window and low prices often prevail during the harvest period.
R.J. Campbell and C. de B. Campbell
Mango (Mangifera indica L.) currently ranks fifth, along with apple, among fresh fruit imported by the United States, with more than 142,000 MT imported in 1995. Imports have doubled in the past 5 years and are projected to increase by 20% to 30% by the year 2000. Mexico supplied >80% of the imported volume in 1995, with the remaining 20% supplied by Brazil, Ecuador, Guatemala, Haiti, Nicaragua, Peru, and Venezuela. Individual production areas (countries) have traditionally controlled a market, defined by time of year, resulting in a near 12-month supply of mangos in the United States in the past few years. However, market share among producing countries is rapidly changing as individual producers and production regions extend their season through the use of different available microclimates, bloom manipulation, and new cultivars. With this extension of production season in each region, there is now significant market overlap and traditional regional windows have been shortened or eliminated. Producers in all regions must now make timely management decisions to assure their future profitability. A holistic management scheme involving attention to fruit quality, cultivar selection, volume consistency, and marketing is presented. Such a management plan is key to an individual region's success in establishing and holding a given market window.
Kent D. Kobayashi and H.C. Bittenbender
In 1988, the Farmer's Bookshelf started out as a computerized information system of crops grown in Hawaii. The first version was created on an Apple Macintosh computer using a hypermedia program called HyperCard. Because HyperCard came with each Macintosh computer, only the crop files needed to be sent to clientele. As the demand for an IBM-compatible version of the Farmer's Bookshelf increased, the Windows version was created using a hypermedia program called Plus. In addition to the crop files, the runtime version of Plus was also distributed to clientele. Later, other files were added to the Farmer's Bookshelf, including files to diagnose problems of macadamia in the field, select ground covers, select landscape trees, recommend fertilization, calculate nut loss for macadamia growers, and calculate turfgrass irrigation. Cost of analysis spread-sheets for several crops were also added. Recently, the Farmer's Bookshelf was moved to the World Wide Web, which has the advantages of reaching a world-wide clientele, easier updating and modifications, and linking to sites of related information. We have added links to newspaper articles on agriculture in Hawaii, to related sites on a particular crop, to on-line agricultural magazines and newsletters, to agricultural software, to upcoming agricultural events, and to Y2K sites. Because of the benefits of the Web version, the diskette versions (Macintosh and Windows) are no longer supported. Putting the Farmer's Bookshelf on the Web has allowed us to better meet the needs of our clientele for up-to-date information.
Wesley T. Watson*, David N. Appel, Michael A. Arnold, Charles M. Kenerley, and James L. Starr
Several techniques have been used to study root growth and pathogen movement along roots between trees, including profile walls, micro-rhizotrons, and soil cores. These assessments can be very time consuming, cost prohibitive, and ineffective when studying soilborne pathogen movement across overlapping roots between adjacent trees in an orchard. Three aboveground rhizotrons were designed and constructed to study the movement of Phymatotrichopsis omnivora (Duggar) Hennebert (syn. Phymatotrichum omnivorum Duggar) along overlapping apple roots [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. (syn. M. domestica Borkh. non Poir.)] in simulated orchard conditions. Two experiments involved boxes using either observation windows or micro-rhizotron observation tubes between trees. A third experiment utilized 45-gallon containers (171,457 cm3) joined by innovative observation windows. The container rhizotrons reduced labor and material costs, were more effective at monitoring roots, were more convenient than field measurements, and more closely simulated orchard growing conditions. This method provides several advantages to better study and manipulate the rooting environment of orchard-grown trees.
Gwendolyn H. Pemberton and A.A. De Hertogh
Dutch-grown `Deutschland', `Fanal', and `Rheinland' Astilbe, harvested 1 Nov. 1992 and shipped to the United States, were dissected to determine the stage of floral development after 0, 2, 4, 6, 8, 10, 12, or 15 weeks of 2C storage. Astilbe crowns were also planted after 15 weeks of 2C storage and floral development was determined after 1, 2, or 3 weeks of greenhouse forcing. On arrival, multiflower inflorescences were clearly visible. A pattern of abortion and reinitiation occurred during 2C storage. Floral development was markedly repressed when ecodormancy was imposed, but development resumed during greenhouse forcing. During the observational period, floral organ numbers were variable, and morphological abnormalities were observed. In a second experiment, physiological maturity of the crowns was evaluated by harvesting crowns of `Bumalda', `Europa', `Federsee', and `Rheinland' on 15 Sept., 1 Oct., 15 Oct., 1 Nov., and 15 Nov. in The Netherlands. Optimal harvest period was from 1 Oct. to 1 Nov., depending on the cultivar. Crowns harvested before this period were physiologically immature. Crowns harvested during the 4-week window produced the highest overall plant quality and performed as physiologically mature crowns. Astilbe crowns harvested after the 4-week window produced plants with lower forcing qualities and were determined to be beyond the optimal physiological state for forcing.
J. Anderson and D. Creech
The population of U.S. Asians will increase by 41% and reach 12 million by the year 2000. Chinese cabbage, Pak Choi, Daikon, and Bitter melon have moved out of the ethnic market and are now in mainstream outlets. This study targeted a diverse range of cool and warm-season crops. Besides those listed above, this study evaluated varieties of Asian greens, Chinese brocolli, Allium, edible soybeam, melon, squash, cucumber, edible Chrysanthemum, amaranth, winged bean, yard-long bean, and edible soybean. A randomized complete block design was utilized, with three replications of row length, varying from 10 to 33 feet, depending on species tested. Direct seedlings of cool-season crops in February and September, 1989 resulted in good market quality and yield of many varieties. Work in 1990 will focus on width of the market window, market information, and grower access to markets.
F. D. Moore III and E. E. Roos
An index “internal slope” derived from the cumulative frequency distribution of individual seed leachate conductivities is related to seed quality; the larger the index value the less variation among individual seeds in a sample (100 seeds) and the higher the seed quality. We have recently developed data acquisition/instrurment control/data smoothing/data analysis software which accesses frequency and cumulative frequency distributions of individual seed conductivities and the derived index on an almost continuous basis from the start of the first soaking.
At present, lack of convergence with regard to curve fitting may occur necessitating multiple sampling times. A “window in time” approach is described whereby index estimates during a two-hour interval within the index stability phase are averaged. Evidence of the method's ability to assess seed vigor will be presented.
Greenhouse and field experiments were conducted to determine the influence of transplant age on growth and yield of `Dixie' and `Senator' summer squash (Cucurbita pepo L.). Dry weight and leaf area measurements indicated that 28- to 35-day-old greenhouse-grown transplants grew more slowly after transplanting than plants that were 10, 14, or 21 days old. Older transplants flowered earlier; however, earlier flowering did not result in higher early yields. Transplants of varying ages did not differ greatly in yield and yield components in the field, although all transplants had higher early yields than the directly seeded controls. Results from these experiments suggest that 21 days may be a reasonable target age for transplanting summer squash. If transplanting were delayed by adverse planting conditions, 21-day-old transplants would likely have at least a 10-day window of flexibility before yields would be reduced notably by additional aging.