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  • Author or Editor: K. Owens x
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Drosera spp. are used in alternative medicine as sources of the beneficial naphthoquinone compounds plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) and 7-methyljuglone. Presently, Drosera are harvested from the wild with great detriment to bog habitats. This study focused on the development of a hydroponic rockwool culture of the sundew D. adelae. Tissue-cultured plantlets were raised as transplants in peatmoss. The transplants were planted directly into rockwool slabs primed to pH 6. Three levels of ammonium nitrate fertilizer were applied, the highest level of which approximated natural peat bog levels. Growth and development of the plants was monitored. Plants from each nitrogen treatment were harvested and subjected to extraction with toluene. Subsequently, high-performance gas chromatography was used to separate and quantify the naphthoquinones present in the extract. This method was used for three harvests: harvest of transplants, harvest after 2 months, and after 4 months of active growth.

Free access

Abstract

Aminoethoxyvinylglycine (AVG) at 50,100, and 200 ppm induced staminate flowers on 3 gynoecious cucumber lines in the greenhouse. Both the time of application and the type of water used to prepare the AVG solutions had a significant effect on the node at which conversion from pistillate to staminate first occurred and on the total number of nodes bearing staminate flowers. Plants treated with 100 and 200 ppm AVG were chlorotic for about 10 days after application.

Open Access

Abstract

Silver nitrate at 100, 200 and 400 ppm and aminoethoxyvinylglycine (AVG) at 50, 100 and 200 ppm induced perfect flowers on gynoecious muskmelon (Cucumis melo L. cv. MSU-1G) in the greenhouse. Some phytotoxicity was observed in plants treated with AgNO3 and AVG at the higher concentrations.

Open Access

Abstract

The muskmelon (Cucumis melo L.) breeding population Wisconsin (Wl) 998 was developed jointly by the U.S. Department of Agriculture, the University of Wisconsin, and Michigan State University to provide breeders and seedsmen with a source from which gynoecious inbreds can be developed for use in the production of hybrid cultivars. In addition to a high incidence of gynoecious plants, WI 998 provides other useful plant and fruit characteristics.

Open Access

Cucumber fruit (Cucumis sativus L.) of 13 cultivars were chilled at 2.5C for up to 10 d, Pitting scores after 8 d at 2.5C and 6 d at 20C ranged from 0.0 (none) in `HP 138' to 7.7 (severe) in `Poinsett 76' fruit. Ion leakage, as the increase in conductivity in a 0.3 M mannitol solution bathing excised disks of mesocarp tissue and expressed as % of the total ion content of the tissue, was lowest in `MDR I' (4.5%) and highest in `HP 159' (11%) after 6 d at 2.5C. After 10 d at 2.5C, however, the lowest was in `Navajo' (5.5%) and the highest in `Poinsett 76' (15%). Resistant lines, e.g., `Dasher II' and `HP 138' showed ion leakage of 7.6% and 5.4% after 6 d, and 8.4% and 7.5% after 10 d. Exudates from cut fruit were collected on filter paper. The fresh and dry wt of exudates from fruit held 8 d at 12.5C ranged from 144 to 346 mg and 16 to 47 mg, respectively. Conductivity of the exudates was highest in `PS 34885' (177 uSiemen/cm) and lowest in `Rawa' (83 uS/cm). The fresh wt of exudate from 6 lines ranged from 99 to 164 mg after 10 d at 2.5C followed by an additional 2.4 d at 20C. The % solid-of the exudates was higher in more resistant lines, e.g., `Dasher II' (8%) and `HP 138' (4%) than in more sensitive lines, e.g., `Poinsett 76' (2%) and `MDR I`(2%). Conductivity of the exudates from chilling sensitive lines were higher than from resistant lines, 60 vs. 30 uS/cm, respectively.

Free access

Abstract

The inbred backcross line method was used to analyze the inheritance of fruit length and weight in cucumber (Cucumis sativus L.). Two populations were produced by crossing a small-fruited, adapted breeding line as the recurrent parent with 2 unadapted and large-fruited lines as donor parents. Marker genes were used in both populations to test for Mendelian expectations. Segregation was normal for all markers in both populations. Nevertheless, significant deviations from binomial expectations occurred, indicating that there were difficulties in estimating gene number and genetic variance without bias. Heritability was moderately high for fruit length and intermediate for fruit weight in both populations. No major genes controlling fruit length or weight were detected using the inbred backcross line method, and only estimates of minimum gene number were obtained. Inbred backcross lines having fruit weight equal to or greater than the large-fruited donor parent were recovered in both populations. However, in neither population were lines recovered with fruit as long as those of the donor parent.

Open Access

Abstract

Selected inbred backcross lines from 2 cucumber (Cucumis sativus L.) populations were studied to determine whether genetic variation existed within and between 2 populations for fruit length and weight. F1 hybrids from intra-population diallel and inter-population North Carolina Design II matings were evaluated in 1981 under greenhouse or field conditions. Significant genetic variability was found among selected inbred backcross lines within each population for fruit length and weight. General (GCA) and specific (SCA) combining ability estimates were significant, indicating that both additive and nonadditive effects were important for trait expression among lines from the same population. Analysis of inter-population design II F1 hybrids indicated that male and female (GCA) or additive effects accounted for most of the variation between lines for fruit length and weight. Significance of specific combinations (SCA) and the F2 data confirmed that genetic variation existed between populations. Therefore, selection and intercrossing of specific inbred backcross lines from both populations may lead to maximum fruit size and recovery of the desired horticultural characterisics of the recurrent parent. The inbred backcross line method is well suited for the transfer of genes controlling a quantitative trait from an unadapted or exotic source into a commercially acceptable type.

Open Access

Abstract

Monoploid genotypes (2n = x = 12), derived by anther culture of a diplandrous (2n pollen-producing) clone of Solanum phureja Juz. & Buk., a South American diploid potato species, were examined for their use in germplasm development. Nine monoploid genotypes and the anther-donor genotype were grown in three chambers (10-, 14-, and 18-hr daylengths) to examine the effect of photoperiod on tuber yield and to determine the variability for critical photoperiod for tuberization. Significant differences were found among the monoploid genotypes for tuber weight and tuber number. Longer photoperiod treatments decreased and delayed tuberization. Axillary tuber formation from single-node cuttings was used to estimate the onset of tuber induction and demonstrated variability among monoploid genotypes for critical photoperiod for tuberization.

Open Access