Organic farming has increased to a $4.2 billion industry in the U.S. and continues to expand ≈20% annually. In Iowa alone, organic acreage for all crops has increased from 13,000 in 1995 to 120,000 in 1998. Organic farmers have requested an unbiased analysis of natural soil amendments/fertilizers and compost products on the market for certified organic vegetable and herb production. In our first-year trials at the ISU Muscatine Island Research Farm in 1998, a total of 1,120 `Hungarian wax' pepper plants were transplanted into rows at 31 × 61-cm spacing. Four replications of seven fertilization treatments were planted within the field. The goal of the fertilization program was to obtain equivalent nitrogen and calcium rates in the organic and conventional systems. Leaf height was not significantly different in plants fertilized with organic compost (poultry litter-based) at 50 and 100 kg/ha N compared with conventional fertilizers (at 100 kg/ha N). All organic and conventional treatments had greater biomass than the organic and conventional controls (no fertilizer), respectively (ANOVA, P = 0.05). First harvest fresh weights were greater in the organic treatments, with the greatest number of peppers and greatest fresh weight in the compost plus Bio-Cal® (a liming industry by-product) treatment. Total pepper fresh weight over the five harvest periods was not significantly different among treatments, demonstrating to organic farmers that comparable yields can be obtained in systems employing alternatives to synthetic nitrogen fertilizer.
Stephen L. Love, Asunta Thompson-Johns, and Timothy P. Baker
Eight hundred and fifty-three clones of Russet Burbank and 1012 clones of Lemhi Russet were obtained from Native Plants, Inc. in 1988. The clones were produced via a tissue culture system designed to produce somoclonal variants. Four cycles of selection were completed from 1988-1991. Selection was based on resistance to blackspot bruise, a tuber flesh discoloration caused by condensation of free tyrosine; or the ability to produce light french fry color following cold storage. At the end of the four selection cycles all but six Russet Burbank clones and seven Lemhi Russet clones were eliminated. ANOVA across years was completed for the eleven somaclonal variants and Russet Burbank and Lemhi Russet checks.
Of the Russet Burbank clones, three were significantly (p = .05) more resistant to blackspot bruise and one had significantly better fry color after cold storage. All four clones had significantly reduced yield in comparison to the check clones. Of the Lemhi Russet clones, three were significantly more resistant to blackspot bruise, and four had significantly better fry color than the check clone. Only one of the seven clones (one with superior fry color designated L1908) did not show a significantly lower yield potential.
John A. Barden
In 1990, 15-yr-old `Smoothee Golden Delicious' trees on M.9, M.9/MM.111, and MM.111 were used. On each of 4 trees per rootstock, 3 branches (1.0-1.7 cm dia) were selected. On 7 June (45 DAFB), crop loads were adjusted to 3, 5, or 7 fruit per cm2 branch cross sectional area (BXSA), and each branch was girdled. On 6 Sept all fruit were harvested; fruit weight, ground color, percent blush, soluble solids, starch, and firmness were regressed against crop load. Each was negatively related to crop load, most strongly for soluble solids, ground color and blush. Rootstock influenced several factors and some interaction with crop load occurred.
In 1991, heavily cropping 10-yr-old trees of Empire/M.7A were used. One each of 7 trees, branches (1.2-2.0 cm dia) were thinned to 4, 8, or 12 fruit/cm2 BXSA on 5 June (40 DAFB). One branch per crop load per tree was girdled on 5 June. On 29 Sept fruit were harvested for evaluation. ANOVA indicated significant interactions between crop load and girdling for fruit weight, firmness, soluble solids and starch. Each showed a significant negative linear regression with crop load on girdled branches; on ungirdled branches none of the regressions were significant.
Xin Zhao, Edward E. Carey, and Fadi M. Aramouni
Consumers of organic food tend to believe that it tastes better than its conventional counterpart. However, there is a lack of scientific studies on sensory analysis of organic food. A consumer taste test was conducted to compare the acceptability of organically and conventionally grown spinach. Spinach samples were collected from organically and conventionally managed plots at the Kansas State University Research and Extension Center, Olathe. One hundred-twenty-two untrained panelists (80 female and 42 male) participated in this consumer study. Fresh and 1-week-old spinach leaves were evaluated by 60 and 62 consumers, respectively, using a 9-point hedonic scale (9 = like extremely, 5 = neither like nor dislike, 1 = dislike extremely). The ANOVA results showed that fresh organic spinach had a higher preference score than corresponding conventional spinach, although not at a significant level (P = 0.1790). For the 1-week-old spinach, the difference diminished, and instead, conventional spinach had a higher preference rating. Among 61 consumers who made comments regarding the sensory evaluation, 29 claimed that organic spinach was more tasty and flavorful; 19 consumers thought conventional spinach was better; 13 consumers could not tell the difference. Even though this consumer study did not reveal significant differences in consumer preference for organic vs. conventional spinach, further well-designed sensory tests are warranted given the trends indicated in our study. Assessment of sensory attributes of organic vegetables after storage also deserves further attention. Ideally, both consumer tests and descriptive analysis using trained panelists will be considered.
Christina Wells, Karen Townsend, Judy Caldwell, Donald Ham, E. Thomas Smiley, and Michael Sherwood
Landscape trees are frequently planted with their root collars below grade, and it has been suggested that such deep planting predisposes trees to transplant failure and girdling root formation. The objective of the present research was to examine the effect of planting depth on the health, survival, and root development of two popular landscape trees, red maple (Acer rubrum) and `Yoshino' cherry (Prunus ×yedoensis). Trees were transplanted with their root flares at grade, 15 cm below grade or 31 cm below grade. Deep planting had a strong negative effect on the short-term survival of `Yoshino' cherries. Two years posttransplant, 50% of the 15-cm- and 31-cm-deep planted cherries had died, whereas all the control cherries had survived (P< 0.001; 2). Short-term survival of maples was not affected by planting depth. Deep-planted trees of both species exhibited little fine root regrowth into the upper soil layers during the first year after transplant. Four years posttransplant, control maples had 14% ± 19% of their trunk circumference encircled by girdling or potentially-girdling roots; this number rose to 48% ± 29% and 71% ± 21% for 15-cm- and 31-cm-deep planted maples, respectively (P< 0.01; ANOVA main effect). There were no treatment-related differences in girdling root development in the cherries.
Rebecca Grumet, Mary Barczak, Chris Tabaka, and Robert Duvall
A simple, aboveground method to study cucumber (Cucumis sativus L.) root growth was developed using a subsurface herbicide banding technique. Those plants with roots that grow deeper or faster reach the herbicide sooner and exhibit herbicide injury symptoms sooner. Greenhouse pot trials showed that 0.25 or 0.50 kg simazine/ha could be used to produce distinctive symptoms; time to symptom expression increased with the depth of the band from the soil surface. Root washing experiments verified that root length was associated with response time. In field trials, response time and severity of symptoms varied with herbicide concentration, depth, and distance from the seed row, thereby providing an indication of where the roots were in the soil. About 100 diverse cucumber genotypes were tested for differences in root growth rate in the greenhouse and in the field. Time to symptom expression was normally distributed among the genotypes; analysis of variance (ANOVA) indicated significant genotypic differences. This system can be used for cultural or physiological studies, or nondestructively for selection and breeding purposes. If the herbicide is placed sufficiently deep to prevent damage to the cotyledons, the plants are capable of flowering and producing fruit. Chemical name used: 6-chloro-N, N′-diethyl-1,3,5-triazine-2,4-diamine (simazine).
Tina Gray Teague
Four week old watermelon (cv. Royal Sweet) transplants were obtained from long distance (FL) and local (AR) commercial transplant growers and set in plots in a commercial watermelon field near Leachville AR. Transplants (plugs) from AR (Burton's Inc., Tupelo, AR) were grown in inverted pyramid, Todd Flats (model 100A; 5/8″ length X 1/2″ width X 3″ height) (Speedling Inc., Sun City, FL). FL transplants (LaBelle Plant World, LaBelle, FL) were grown in 1.5″ square cells, 2″ deep. All transplants were delivered 15 April and set on 16 April. Transit time for local transplants was < 2 hrs, and plants were delivered in original flats. FL transplants were shipped on 14 April and were in transit ca. 28 hrs. They had been pulled from trays and were shipped in cardboard boxes. Plot size was 6 beds, 53.3m long with treatments arranged in a RCB with 4 replications. Bed spacing was 2.9m with between plant spacing of 1.5m. Data were subjected to ANOVA with mean separation by LSD.
Plots were harvested 3, 8, 15 and 22 July. Total number of fruit produced from plots planted with AR transplants was greater than FL treatment plots in the first 3 of 4 harvests; significantly higher total cumulative yield was observed with AR compared to FL transplants (45,115 and 35,172 kg ha-1, respectively). Increases in-yield and earliness resulted in an increase in gross profit of $1225 ha-1 for local transplants (based on national price data from that time period). No differences in average weights of fruit were observed for any harvests. Results indicate that Mid-South watermelon producers could benefit from utilizing locally grown transplants if plants are of comparable quality to those available from distant suppliers.
Mondher Bouden and Jacques-Andre Rioux
The richness of the organic residues in certain fertilizing elements justifies their valorization in horticulture. However, their contents in pathogenic and toxic elements can restrict their use. In this context, this study was conducted in order to evaluate the effect of three organic residues on the environmental medium and the risks of water contamination by the release of heavy metals. Physocarpus opulifolius `Nanus' was transplanted into four substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). The three other substrates (25% of peatmoss was substituted by organic residue) contained 10% of fresh bio-filters (FBF), 10% of composted sewage sludges (CSS), or 10% of de-inking sludges (CDS). The pots (5l) were placed in plastic vats and the drainage water was recovered in vessels (17l). The experimental design was in complete blocks with six replications. Samples of the drainage water were collected every 2 weeks for analysis. The pots were fertilized every week (400 mg/Ll of N) and growth parameters were statistically analyzed by ANOVA. The chemical analysis of the residues proves that they contain weak concentrations in organic contaminants. There is an accumulation of
Shadd Taylor, Derald A. Harp, Kristen McDowell, and Roque Lemus
It is generally accepted that plants closer to structures benefit from the warmth emitted via imperfect insulation and solar energy reemitted as long-wave, thermal radiation. However, while claims of protection are given, little quantifiable information exists on the extent or pattern of this protection. We studied existing plantings of Trachelospermum asiaticum, an evergreen groundcover that is frequently damaged in northeast Texas. The plantings studied were part of a landscape with at least five different identifiable microclimates: 1) near building (NB); 2) mid-bed (MB); 3) bed edge (BE); 4) beneath Quercus virginiana (LO); and 5) beneath Pyrus calleryana`Bradford' (BP). We placed HOBO temperature data loggers recording one temperature per minute in each location. Following our first damaging freeze, we waited 7 days before collecting leaf samples. Leaf samples were collected by using a 25-cm square, 2 cm deep on two sides. The square was placed on the groundcover so that the top of the groundcover was level with the top of the square. All leaves and stems that extruded through the top 2 cm of the square were excised. Four samples were taken from each location, and the number of damaged and nondamaged leaves were counted for each sample. Leaves that were at least 50% discolored were considered damaged. Leaf damage data were analyzed using SAS Proc ANOVA. Leaves in the BE and BP locations showed significantly fewer live leaves than any other locations. NB leaves were virtually undamaged. Average temperatures in the BE and BP locations were 4.5 to 5 °F colder than the “near building” locations, comparable to an a or b zone in the current USDA Plant Hardiness Zone map.
Shann Tanner, Christina Wells, and Gregory Reighard
The effectiveness of soil solarization as an alternative to methyl bromide (MBr) fumigation in replanted peach orchards was investigated at the Musser Fruit Research Farm near Clemson, S.C. A split plot experimental design was used, with soil treatment as the whole-plot factor and rootstock as the sub-plot factor. In Spring 2002, preexisting trees were removed from the study site, and six orchard rows were cultivated and subsoiled. In June, two rows were covered with clear polyethylene sheeting and solarized for the remainder of the summer. In November, two additional rows were treated with MBr (474.3 kg·ha-1), while the two remaining control rows received no soil sterilization treatment. In Jan. 2003, 36 `Redglobe' peach trees budded on Guardian™ or Lovell rootstock were transplanted to the site, and one minirhizotron was installed beneath each tree. Minirhizotron observations were made every 14–21 days from Feb. through Oct. 2003, and stem caliper measurements were taken on four dates during this interval. Trees grew significantly larger in the MBr and solarized rows than in the control rows (P< 0.1; Tukey's hsd), but there were no differences in stem caliper growth between MBr and solarization-treated trees. Reduced aboveground growth in control trees may have been related to greater carbon expenditure belowground: in the absence of soil sterilization, fine root median life spans were reduced by 27–28 days (P< 0.0001; proportional hazards regression) and rates of root production and mortality were significantly higher (P< 0.1; repeated measures ANOVA). Solarization and MBr fumigation appeared to provide similar benefits in reducing root turnover and improving aboveground growth at this site.