Search Results
Our goal was to develop efficient regeneration protocols for safflower that could be used in conjunction with Agrobacterium tumefaciens -mediated transformation to introduce genes conferring economically important traits. Direct regeneration of whole plants has been achieved from cotyledon and hypocotyl explants of 30-day-old `Centennial' and `Montola' seedlings. Explants transformed with Ti plasmids containing NPTII and the β-glucuronidase (GUS) reporter gene produced kanamycin-resistant calli and shoots testing positive for GUS activity. Current work is incorporating the bar gene into appropriate Ti plasmids that will be used to confer glufosinate herbicide resistance to elite safflower cultivars. An esterase gene from Bacillus subtilis will be introduced to confer resistance to Alternaria carthami leaf spot disease.
Abstract
The effects of peat: vermiculite mixes on increased growth response of radish (Raphanus sativus L. ‘Early Scarlet Globe’) induced by Trichoderma harzianum Rifai (isolate T-12) were investigated. Canadian sphagnum peat and vermiculite were mixed in various ratios to form 0-100% peat mixes. Four levels of T-12 amendment were added to these mixes—0%, 2%, 5%, and 10% (v/v) or 0%, 0.1%, 1%, and 10%. In general, increasing levels of T-12 amendment induced linear increases in radish dry weights after 4 and 5 weeks. Greatest increases were seen in mixes containing 20% peat or 80% peat. The smallest increases were observed when T. harzianum was added to 0% peat or 100% peat mixes. There was no effect on the population densities of T-12 after it was introduced into the mixes. No Pythium spp. or root disease were detected in the mixes, suggesting that T. harzianum, a biological control agent, can increase plant growth independent of any detectable root pathogens.
Abstract
An array of 102 single and 3-way cross hybrids of pickling cucumbers (Cucumis sativus L.) were evaluated for yield over 2 years under field conditions. Hybrids were produced by crossing lines with gynoecious, monoecious, hermaphroditic, and androecious expression. The significant correlations between femaleness (percent pistillate nodes) and marketable yield were 0.34 for single cross and 0.45 for 3-way cross hybrids. Highest yields were obtained from the single crosses of gynoecious × androecious, and gynoecious × hermaphrodite, followed by the 3-way cross of (gynoecious × hermaphrodite) × androecious, on the basis of either total or marketable fruits per plant. Hybrids having androecious pollen parents exhibited more femaleness and produced higher yields than those with monoecious pollen parents. The possible use of these high yielding parental sex combinations as hybrid cultivars in place of conventional single crosses (gynoecious × monoecious) might improve the production of pickling cucumbers for once-over mechanical harvest.
Triploid watermelon (Citrullus lanatus Thunb.) was grown on the same plots in 1990 and 1991 and fertilized with either poultry litter or commercial fertilizer. Additional treatments included bare soil or plots mulched with black polyethylene, and plots with or without spun-bonded fabric row covers over both bare soil and mulch. Watermelon yields were unaffected by fertilizer source in 1990 butwere significantly higher for poultry litter than for commercial fertilizer treatment in 1991. Polyethylene mulch significantly increased postharvest soil NO3 and leaf N concentrations in 1990 and increased yield and yield components in both years. There were no beneficial effects of row covers on yield in either year, presumably because no early-season freezes occurred.
Triploid watermelon (Citrullus lanatus Thunb.) was grown on the same plots in 1990 and 1991 and fertilized with either poultry litter or commercial fertilizer. Additional treatments included bare soil or plots mulched with black polyethylene, and plots with or without spunbonded fabric row covers over both bare soil and mulch. Watermelon yields were unaffected by fertilizer source in 1990 but were significantly higher for poultry litter than for commercial fertilizer treatment in 1991. Polyethylene mulch significantly increased postharvest soil NO3 and leaf N concentrations in 1990 and increased yield and yield components in both years. There were no beneficial effects of row covers on yield in either year, presumably because no early-season freezes occurred.
Abstract
Optimum conversion to staminate flowering in hermaphroditic lines of pickling cucumber (Cucumis sativus L.) was obtained with 3 to 4 applications of 200-400 mg/liter of silver nitrate (AgNO3) at 4-day intervals, with initial treatment at the first true leaf stage.
In a field experiment, fertilizer source (poultry litter vs. commercial), plastic mulch, row cover, and fertilizer rate (residual from 1990 study vs. additional) were applied in factorial combinations to determine the effect on vegetative growth and production of triploid watermelons. Litter (3.12 % total N) was re-applied at the rate of 13.2 Mt·ha-1 along with commercial fertilizer (6N-10.5P-20K) at 1.1 Mt·ha-1. Plastic mulch showed the greatest influence on vegetative growth and production variables by increasing vine length 26.1 cm, leaf area 61.8 cm2, yield 4207 kg·ha-1, melon number 741 ·ha-1, and average melon weight 0.8 kg, over unmulched plots. Plastic mulch with or without row cover increased melon number significantly when compared to plots without mulch or row covers. Poultry litter increased vine length, yield, and average melon weight 15.4 cm, 1971 kg·ha-1, and 0.5 kg, respectively, when compared to commercial fertilizer. Poultry litter in combination with row cover increased yield by 3864 kg ·ha-1 over commercial fertilizer with row cover, and approximately 2567 kg·ha-1 over poultry litter and commercial fertilizer without row cover. Additional fertilizer increased average melon weight 1.3 kg.
Response of triploid watermelon [Citrullus lanatus (Thunb.) cv. Tiffany] to fertilizer source (FS) [poultry litter (PL) vs. commercial fertilizer (CF)1, black plastic mulch (BPM), and spunbonded floating row cover (SFC) was evaluated in 1990 on an East Texas Fuquay-Darco sandy loam soil. Plant growth and percent soluble solids were equated by FS. Vine fresh weight, number and total melon weight per plot, average melon weight, and percent soluble solids were increased 27%, 29%, 45%, 24%, and 17%, respectively, by BPM when compared to no mulch treatment. BPM + SFC treatment decreased vine fresh weight but increased total melon number which in turn increased plot weight. PL increased plant P, K, and Mg 16%, 12%, and 24%, respectively, when compared to CF. Plant Ca was increased 21% by CF. Plant N, P, Ca, and Mg were increased 18%, 16%, 22%, and 15% by the use of BPM. A reduction in plant N was found when SFC was used alone and with treatments lacking BPM or BPM + SFC. Mean soil temperature was increased on the average 2°C at 10 cm depth by BPM when compared to all other treatments. Mean 24 hr air temperature 2 cm above BP and bare ground under SFC was increased 5°C above ambient.
Abstract
The effects of 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2, 1, 3-benzothiadiazole (MCEB), a proposed inhibitor of ethylene action, and (2-chloroethyl) phosphonic acid (ethephon) on sex expression were observed in androecious and gynoecious phenotypes of cucumber (Cucumis sativus L.) under greenhouse conditions. MCEB had no effect on the androecious phenotype while ethephon (50 ppm) induced pistillate flowers. The effect of MCEB and ethephon treatment was a marked reduction in the number of ethylene-induced pistillate flowers except when there was a 48-hour period between applications of ethephon and MCEB. In the gynoecious phenotype, MCEB (75 ppm) induced staminate flowers, ethephon had no effect, and the effect of MCEB and ethephon treatment was to induce staminate flowers at relatively high concentrations of MCEB (150 ppm).
Abstract
Clonal multiplication of carnation (Dianthus caryophyllus L.) was accomplished in three stages: 1) shoot tip culture initiation stage, 2) shoot multiplication stage, and 3) rooting stage. The culture medium for the initiation stage was examined by comparing various inorganic salt mixtures, vitamin mixtures, carbohydrates, growth regulators, agars, pH’s, and additional supplements for their effect on growth and development of multiple shoots from shoot tips. When shoot tips (ca. 1 mm high) were grown on a modified Murashige and Skoog medium with 10 µM kinetin and 1 µM NAA, apical dominance was counteracted and morphologically normal shoots proliferated rapidly. Transferring these cultures after 4 wk to 100 ml flasks (one per flask) with 50 ml of same medium without agar and supplements, and with the kinetin concentration reduced to 2.5 µM, resulted in an average per original shoot tip of 28 shoots over 2 cm in height being produced in another 3 weeks. These shoots were rooted in BR-8 blocks or Jiffy-7 peat pellets under intermittent mist. Plantlets rooted in these supports were transferred easily to greenhouse conditions. Incorporation of carnation micropropagation into a pathogen-free propagative stock program should not be difficult, and might prove beneficial even if large scale use is limited by economic considerations.