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A seasonal study was conducted to assess the freezing injury of `Boskoop Giant' black currant (Ribes nigrum L.) samples from Oct. 1991 through Mar. 1992. Buds were subjected to either differential thermal analysis (DTA) or one of a series of temperatures (0 to -36C). Freeze injury was then assessed either visually or with TTC. Results indicated that black currant floral buds have multiple low-temperature exotherms (LTE). Freeze injury in intact buds could not be visually quantified because of the lack of visible browning, nor assayed with TTC reduction. Excised floral primordia incubated in TTC, however, developed colored formazan following exposure to nonfreezing and sublethal freezing temperatures, but remained colorless when exposed to lethal temperatures. The percentage of floral primordia that were colored and colorless were tabulated and a modified Spearman-Karber equation was used to calculate the temperature at which 50% of floral primordia were killed (T50 The T50 temperature was correlated with the temperature at which the lowest LTE was detected (R2 = 0.62). TTC reduction assay using excised floral bud primordia was a good indicator of viability in frozen blackcurrant buds. Chemical name used: 2,3,5-triphenyltetrazolium chloride (TTC).

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measured. Relative EL (Rt) was calculated as Rt (%) = (EC1/EC2) × 100. TTC test. One 1-cm-long section was cut from the apical, middle, and basal parts of each shoot, and placed in a tube, to which 10 mL 0.5% 2,3,5-triphenyltetrazolium chloride (TTC) was

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opened for removing seed samples, bar = 2 cm. ( B ) 2,3,5-Triphenyltetrazolium chloride (TTC)–positive red coloration of viable seeds observed under a stereomicroscope (4×), bar = 1 mm. ( C ) In vitro seed germination and protocorm development (90 d after

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( n = 3). The effects of PGRs on root 2,3,5-triphenyltetrazolium chloride-reducing activity under suboptimal temperature stress. As shown in Fig. 5 , under normal conditions (day 0), the root TTC-reducing activity in ‘Zhongshu6’ was similar to that

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2,3,5-Triphenyltetrazolium chloride (TTC) reduction measures glucose equivalents of substances diffusing from plant tissues. Amounts of diffusing substances are greater from cold-hardened than unhardened citrus. These differences are colorimetrically distinguishable and identify citrus plants exposed to low temp in controlled environment studies.

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. (2009 ), we used 0.5% triphenyltetrazolium chloride (TTC) buffer solution and a culture medium (10 g·L −1 agar + 0.1 g·L −1 boric acid + 100 g·L −1 sucrose solution) combined with the in vitro germination method to detect the pollen vitality

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Abstract

Ethylene and ethane production of freeze-stressed rhododendron (Rhododendron sp. ‘Sappho’) leaf disks were compared to visual rating, TTC reduction, and electrolyte leakage as possible means of measuring tissue viability. Ethane production, as caused by freezing temperatures, was highly correlated with visual rating, TTC reduction, and electrical conductivity (r = 0.96, r = −0.81, and r = 0.96, respectively). Ethylene production peaked concurrently with initial stages of visual tissue damage, then decreased as the temperature was lowered until complete death occured. Ethane production and electrolyte leakage peaked coincidentally with the decrease of ethylene. Ethylene:ethane ratios are suggested as a measurement of freeze-induced tissue damage. This study supports the view that ethylene production is related to stress and ethane production to cell death. Chemical names used: 2,3,5-triphenyltetrazolium chloride (TTC).

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The perennial nature, prolific white to pink racemes, and attractive foliage and form of october flower [Polygonella polygama (Vent.) Engelm. & A. Gray] and sandhill wireweed [Polygonella robusta (Small) G.L. Nesom & V.M. Bates] suggest that these wildflowers could have significant ornamental and landscape potential if an effective propagation method could be developed. However, a paucity of seed biology information exists for these species. Two- to 4-month-old seeds of both species were tested for viability using triphenyltetrazolium chloride (TZ) before germination experiments. Initial viability of seed lots was 77.4% ± 6.3% and 53.5% ± 6.8% for october flower and sandhill wireweed, respectively. Initial germination tests showed that both species had the highest number of germinated seeds in cool temperatures (22/11 °C day/night), but a portion of the seed population remained dormant. Germination of both species at simulated seasonal temperatures indicated that seeds require a warm, moist period (warm stratification) before germination starts at cooler temperatures. Germination of both species also increased when gibberellic acid (GA3) was applied at the highest rate of 1000 ppm. We conclude that seeds of both species exhibit non-deep physiological dormancy.

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Cryopreservation in liquid nitrogen (LN) is relatively routine for many small, desiccation-tolerant (orthodox) seeds. Seeds of Pyrus species are considered orthodox but have not been evaluated for LN storage. Seeds of freshly collected P. communis L. (`Bosc') were evaluated for germinability and by TZ staining after exposure to four LN treatments: 1) direct immersion and direct removal; 2) direct immersion and 1 minute in LN vapor phase before removal; 3) 2 minutes in vapor phase before immersion and direct removal; and 4) 2 minutes in vapor phase before immersion and 1 minute in vapor phase before removal. Fresh `Bosc' seed viability evaluated by TZ and greenhouse germination tests remained high (83% to 100%) following four types of LN treatments, compared to the controls (77% to 87%). Differences in `Bosc' seed viability were small and TZ results showed no significant differences among the LN treatments. Direct LN immersion and removal resulted in significantly more greenhouse-germinated `Bosc' seeds than the other treatments and fewer control seeds germinated than any LN treated seeds. Fresh `Bosc' seed cryopreserved at 7.9% moisture exhibited high germinability by both TZ and germination tests. LN exposure caused no physical damage to the seeds. Chemical name used: 2,3,5-triphenyltetrazolium chloride (TZ).

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2,3,5-triphenyltetrazolium chloride (TTC) staining and electrical impedance (?) analyses of apple roots (Malus domestica Borkh. `Beautiful Arcade') taken in late March from either the field or from 3C refrigerated storage (cold-stored). LT50 levels using TTC were much lower than those found using electrical impedance. No loss of viability in the roots was detectable using TTC staining until a freeze–thaw stress of –9C whereas? analysis detected changes in cell viability after a freeze–thaw stress of only –3C. With increasing cold stress, two parameters: extracellular electrical resistance (Ro) and time constant?, decreased linearly for cold-stored roots and exponentially for field roots. Impedance analysis also revealed that the values for both extracellular Ro and total tissue electrical resistance (R?) for the field roots were approximately 5 and 8 times lower, respectively, than in the cold-stored roots. It is believed that the smaller Ro and R? values obtained from the field roots were due to natural in-field freeze–thaw cycling prior to the controlled stress tests in the laboratory. Based on the analyses of winter hardiness using the two methods, the impedance technique? provided the physiological information not only about the hardiness level, but also about freeze–thaw history prior to the hardiness assessment.

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