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Matthew H. Kramer, Ellen T. Paparozzi and Walter W. Stroup

should review the soon to be published ASHS Statistical Guidelines for Authors. In a research manuscript, authors, at a minimum, need to include enough information on their experiment design (e.g., levels of blocking or other constraints on randomization

Open access

Matthew H. Kramer, Ellen T. Paparozzi and Walter W. Stroup

should review the soon to be published ASHS Statistical Guidelines for Authors. In a research manuscript, authors, at a minimum, need to include enough information on their experiment design (e.g., levels of blocking or other constraints on randomization

Open access

Matthew H. Kramer, Ellen T. Paparozzi and Walter W. Stroup

should review the soon to be published ASHS Statistical Guidelines for Authors. In a research manuscript, authors, at a minimum, need to include enough information on their experiment design (e.g., levels of blocking or other constraints on randomization

Free access

Andrew Riseman and Richard Craig

Research in Penn State's Exacum breeding program has revealed genotypic variation for the development of zinc deficiency, which may indicate the presence of zinc efficiency factors. Through preliminary experiments, we have identified both genetic families and individual genotypes that can be classified as either zinc-efficient or zinc-inefficient. Chi-square contingency analyses indicate significant differences (P < 0.001) in segregation patterns for zinc deficiency among hybrid families. Segregation patterns within families ranged from 100% of the progeny developing zinc deficiency to 100% of the progeny remaining healthy. Two genotypes contrasting in zinc efficiency have been identified and used in experiments designed to investigate physiological factors related to zinc efficiency. The zinc-efficient genotype has a significantly higher ability to decrease solution pH (P < 0.01), significantly higher root cation exchange capacity (P < 0.007), significantly lower root/shoot ratio (P < 0.001), significantly lower water loss/cm2 leaf (P < 0.03), and significantly higher fresh weight/dry weight ratio (P < 0.001). Research on zinc uptake rates is currently being conducted utilizing the efficient and inefficient genotypes. Based on all of our research, we conclude that 1) a strong genetic effect is involved in the zinc nutritional status of interspecific Exacum hybrids and 2) a number of physiological traits differ between zinc-efficient and zinc-inefficient genotypes.

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Elattir Hassan and Youness Chabi

Citrullus vulgaris cv Rocio hybrid F1 was seeded 18 Jan. 1994 and transplanted 1 month later in loam-sandy soil at the experiment station of the Complexe Horticole, 16 km south of Agadir. Watermelon plants grown under perforated plastic rowcover with 800 holes per square meter were compared to the open-field plants. The experiment design used was a randomized block design with two treatments (rowcover and open field) and four repetitions. Rowcover was put at planting and removed 90 days later. Under the rowcover the minimal and maximal temperatures were higher than the ones of the open field by 0.9 to 2.4 and 3 to 6.8 °C, respectively. Soil temperatures at 10-cm depth measured at 7:00 am and 4:00 pm were higher under cover by 1.2 and 2.7 °C, respectively. Early yield of watermelon obtained under perforated plastic rowcover and in open field were 6.55 kg/plant (78.6 t/ha) and 2.45 kg/plant (29.4 t/ha), respectively.

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Jack Staub, Karl Poetter and Robin Fruth

Fruit yield in cucumber is limited by the nature of its fruiting habit. Manipulation of plant architecture is one way of increasing yield potential in cucumber. We are incorporating a multiple lateral (ML), sequential fruiting habit into a determinate (de) background. Misclassification of mature plants occurs because the de character is difficult to identify in a ML/de background. It would be valuable to develop an inexpensive laboratory test which would allow accurate classification of ML/de plant types. To develop such a test, we have begun the use of a new DNA marker system, random amplified polymorphic DNA (RAPD). We performed a series of experiments designed to test the reproducibility and predictability of RAPDs. Data indicated that RAPD patterns were not significantly affected by tissue age, infection with powdery mildew or bacterial wilt, or presence of fruit. F1 RAPD polymorphisms segregated in predicted 3:1 ratios. A survey of 6 ML lines and 1 de line with 400 primers identified 4 polymorphisms shared by all ML lines and diagnostic for the de line. No association was found between any of these markers and the de character.

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John O. Williams III, Nick Gawel and Jiang-Tian Ling

The lengthy generation times associated with woody ornamentals has led to the exploration of alternatives to traditional breeding methods for the development of new cultivars. This report summarizes the results of experiments designed to examine the feasibility of altering plant morphology by DNA assimilation following electroporation of intact seedlings. Brassica rapa (a nonwoody plant) was chosen as a model plant for initial experiments due to its rapid development and short generation time. Seedlings were subjected to either one or five 300-V pulses (99 ms) in the presence or absence of foreign DNA. Foreign DNA used was Ulmus parvarvifolia at a concentration of 200 μg·mL–1. Results indicate a lower survival rate of seedlings electoporated in the presence of DNA. Data were recorded after 21 days for plant height and leaf number. No significant differences were noted for plant height. However, significantly more leaves were produced on plants electroporated (five pulses) in the presence of foreign DNA. These results suggest the possible utilization of this technique for induction of variation in other plants.

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A-M. Boland, P.D. Mitchell, I. Goodwin and P.H. Jerie

An experiment designed to study the effects of different root volumes was installed in Fall 1991. `Golden Queen' peach trees [Prunus persica (L.) Batsch.] were planted into different isolated soil volumes (0.025, 0.06, 0.15, 0.4, and 1.0 m3), which were essentially individual drainage lysimeters. Trunk cross-sectional area (TCA) increased from 5.76 to 14.23 cm2 for the smallest and largest volumes, respectively, while leaf area was 4.56 and 21.32 m2 for the respective treatments. Leaf size was not affected by soil volume. Soil volume was positively related to the number of lateral shoots produced, lateral shoot density, and internode length. Total flower bud number and flower bud density were inversely related to soil volume. Fruit set was similar among treatments despite an almost 4-fold difference in tree size. Tree water use (liters·mm-1 pan evaporation) increased with soil volume; however, when adjusted for tree size (tree water use per TCA), there were no consistent differences between treatments for tree water use over the season. These results suggest that trees planted in the smaller soil volumes were more efficient reproductively per unit of tree size and would be easier to manage in an ultra-high-density planting.

Free access

Domingos P. F. Almeida and Donald J. Huber

Chilling injury limits the postharvest handling of many fruit and vegetables. In low-temperature storage trials, control treatments typically consist of fruit stored above the injury threshold. Since chilling exposures for tomato fruit often exceed 2 weeks, controls stored above the threshold continue to ripen, confounding comparisons with fruit maintained at low temperatures. In this study, the ethylene action inhibitor 1-MCP was used to arrest ripening to permit more valid comparisons between fruit stored under the two temperature regimes. Mature-green tomatoes were treated with EthylBloc and then stored at 5 or 15 °C for 2 or 3 weeks after which time the fruit stored at 5 °C were transferred to 15 °C to allow the expression of injury symptoms. 1-MCP inhibited ripening of fruit stored at 15 °C for 2 to 3 weeks. Color, pericarp firmness, and pectin solubilization of MCP-treated fruit stored at 15 °C remained at the values of mature-green fruit, validating their use as controls for these physiological characteristics. After 2 to 3 weeks at 15 °C, MCP-treated fruit resumed normal ripening. Comparing the fruit removed from low-temperature storage with nonripening controls at 15 °C revealed that storage at 5 °C for 2 to 3 weeks decreased the hue (yellowing) but did not affect chroma or lightness, maintained firmness, and did not affect pectin metabolism. Electrolyte leakage increased or remained unaffected by cold storage. MCP-treated fruit had slightly higher electrolyte leakage than non-MCP-treated fruit after storage at either 5 or 15 °C. We conclude that MCP-treated fruit provide adequate controls in experiments designed to study many aspects of low-temperature storage.

Free access

Deepak Dandekar, G. K. Jayaprakasha and Bhimanagouda Patil

Citrus consumption has been shown to promote human health due to presence of several bioactive compounds. In the process of understanding the health benefits of citrus, we need to isolate and characterize these compounds. Limonoids are one of such prominent, but lesser-known phytonutrients that have been shown to prevent cancers of the mouth, skin, lung, breast, and colon. With the growing interest in the health-promoting properties of citrus limonoids, the demand for these bioactives has significantly increased. It has been critical to explore environment-friendly extraction methods rather than using hazardous organic solvents. A water-based hydrotropic extraction of limonoid aglycones from sour orange (Citrus aurantium L.) seeds was developed. Two hydrotropes, sodium salicylate (Na-Sal) and sodium cumene sulfonate (Na-CuS), were studied for extraction efficiency using the Box Behnken experiment design method. The extraction efficiency of prominent aglycone limonin was observed depending on hydrotrope concentration, extraction temperature, and percentage of raw material loading. Response Surface Analysis (RSA) of data predicted the optimum conditions for maximum yield. Recovery of aglycones from filtered extract is also easily achieved by mere dilution using water at pH 3 or 7 or by partitioning the extract with dichloromethane. At optimum conditions, limonin yield of 0.46 mg/g seeds in the case of Na-Sal extraction and 0.65 mg/g seeds in the case of Na-CuS extraction was achieved. The results demonstrated that the hydrotropic extraction process of limonoid aglycones has practical commercial importance. This project is based upon work supported by the USDA–CSREES IFAFS #2001 52102 02294 and USDA–CSREES #2005-34402-14401 “Designing Foods for Health” through the Vegetable and Fruit Improvement Center.