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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.

Open Access
Authors: , , and

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.

Open Access

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.

Free access

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.

Full access

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.

Free access

Abstract

Ethephon applied as a foliar spray caused an androecious (all-male) line of Cucumis sativus L. to produce pistillate flowers analogous to those of monoecious phenotypes. The degree of conversion depended on the concentration of ethephon and stage of growth at the time of application. In the greenhouse, a concentration of 50 ppm applied at the 3- or 4-leaf stage was the best treatment for induction of pistillate flowers without marked inhibition of growth.

Open Access
Authors: , , and

Abstract

Parthenocarpic fruiting of genetically parthenocarpic and non-parthenocarpic pickling cucumber lines was determined under different thermo-photoperiods. The genetically parthenocarpic line, MSU 364G, produced both earlier and more fruits under all thermo-photoperiod treatments than the genetically non-parthenocarpic line, Gy 3. This was especially true at high night temperatures (18°C). Thus, maximum selection pressure for yield in genetically parthenocarpic lines might be best exerted under high night temperatures. Conversely, the production or yield of parthenocarpic fruits was greatest under low night tempeartures (12°C). Hybrids involving either of these 2 parental lines and 2 hermaphroditic lines were intermediate for parthenocarpic yield. Yield of parthenocarpic lines was associated with intensity of femaleness, i.e., strong femaleness resulted in earlier fruiting and greater numbers of parthenocarpic fruits. The development of parthenocarpic pickling cucumber cultivars for once-over mechanical harvest seems practical by combining parthenocarpic with gynoecious genotypes.

Open Access

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.

Open Access

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).

Open Access

Abstract

Postclimacteric respiration of apples (Malus pumila Mill. cv. Baldwin) decreased as peel Ca level increased from 400 to 1300 ppm. The respiratory climacteric occurred simultaneously in fruit of all Ca levels, indicating that maturation was unaffected by these Ca levels. Occurrence of bitter pit was inversely related to Ca levels. Scald, internal breakdown, and decay were more prevalent when peel Ca was below 700 ppm. Fruits were firmer after 5 months storage in 0°C air if Ca was below 700 ppm, although they were larger, yellower, and more susceptible to decay and other disorders than higher Ca fruit.

Open Access