Silver Thiosulphate Treatment Research Articles

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light, 6-Benzyl Adenine, and Silver Thiosulphate Treatments.

Understanding pollen and ovule fertility as factors influencing fruit and seed set is important in cassava breeding. Extended daylength with red light (RL) and plant growth regulators (PGRs) have been used to induce flowering and fruit set in cassava without any reference to effects on pollen viability or ovule fertilizability. This study investigated the effects of field-applied RL and PGR on pollen viability and ovule fertilizability. Panels of cassava genotypes with early or moderate flowering responses were used. RL was administered from dusk to dawn. Two PGRs, 6-benzyl adenine (BA), a cytokinin and silver thiosulphate (STS), an anti-ethylene, were applied. Pollen viability was assessed based on pollen grain diameter, in vitro stainability, in vivo germinability, ovule fertilizability, and ploidy level. Treating flowers with RL increased the pollen diameter from 145.6 in control to 148.5 µm in RL, 78.5 to 93.0% in stainability, and 52.0 to 56.9% in ovule fertilizability in treated female flowers. The fruit set also increased from 51.5 in control to 71.8% in RL-treated female flowers. The seed set followed a similar trend. The ploidy level of pollen from RL-treated flowers increased slightly and was positively correlated with pollen diameter (R2 = 0.09 *), ovule fertilization (R2 = 0.20 *), fruit set (R2 = 0.59 *), and seed set (R2 = 0.60 *). Treating flowers with PGR did not affect pollen diameter but increased stainability from 78.5% in control to 82.1%, ovule fertilizability from 42.9 to 64.9%, and fruit set from 23.2 to 51.9% in PGR-treated female flowers. Combined BA + STS application caused the highest ovule fertilizability, fruit, and seed set efficiency. These results show that RL and PGR treatments increase pollen viability and ovule fertilizability. This is important for planning pollination strategies in cassava breeding programmes.

Effect of Ethylene Antagonist Silver Thiosulphate on the Flower Longevity of Clarkia pulchella Pursh.

Abstract An experiment was conducted to study the effect of different concentrations of silver thiosulphate (STS) on flower longevity of Clarkia pulchella Pursh. The buds were subjected to 0.1, 0.25, 0.5, 0.75 and 1 mM of STS for 1 h pulse treatment. A separate set of flowers kept in distilled water was designated the control group. STS treatment resulted in improved flower longevity besides maintaining higher fresh and dry mass, water content and floral diameter. Conversely, total phenols, lipid peroxidation and lipoxygenase (LOX) activity decreased. The flowers treated with STS showed a significant increase in the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Amongst various grades used, 0.5 mM STS was found to be most effective in enhancing the flower longevity by 1.5 days. The present study reveals that STS maintains lower LOX activity, thereby increased membrane stability index by improving the activity of antioxidant enzymes.

An investigation of ethylene sensitivity in three Australian native cut flower genera, Calothamnus , Grevillea and Philotheca

Abstract Knowing a plant’s sensitivity to ethylene is crucial in order to negate ethylene-mediated senescence with inhibitors such as silver thiosulphate (STS) or 1-methylcyclopropene (1-MCP). The ethylene sensitivity of three exported Australian native flowers, Calothamnus quadrifidus, Grevillea ‘Superb’ and Philotheca myoporoides was previously unknown. The first two of these three species produced steady amounts of ethylene during vase life. The vase life of all three species was not significantly shortened after exposing the flowers to ethylene (10 μL L−1 for 12 h). However, STS treatment (0.5 mM pulse for 12 h prior to ethylene exposure) significantly extended the vase life of G. ‘Superb’ from 7 d (control) to 10 d. In contrast, 1-MCP (10 nL L−1), applied either at the same time as ethylene exposure, or 12 h prior to challenging plants with ethylene, did not result in significant differences in vase life over the control for any of the three species. Ethylene production was comparable between the STS and 1-MCP treatments for G. ‘Superb’ over the 11 d test period and was less than that of the control. Endogenous production of ethylene did not appear to relate to longevity or the effectiveness of the protectants. Our results indicate that the treatment of C. quadrifidus and P. myoporoides with ethylene inhibitors is unnecessary and is therefore not recommended. The positive effect of STS on G. ‘Superb’ was not linked to ethylene sensitivity, but may relate to another of the beneficial properties of STS, such as an ionic effect.

Action of ethylene, 1-methylcyclopropene and silver thiosulfate in two developmental stages of potted ornamental pepper

The species of Capsicum genus have great genetic variability with enormous potential for marketing as ornamental potted plants. The exposure at ethylene induces various deleterious responses during plants life cycle, but there are few studies on how the ethylene affects early developmental stages of these ornamental plants. Thus, this study aimed to evaluate the effects of the application of ethylene and ethylene inhibitors, 1-methylcyclopropene (1-MCP) and silver thiosulphate (STS) in two early development stages (seedling or initial flowering) of potted ornamental peppers of the cultivars ‘Calypso’ and ‘MG 302’. Cultivar ‘MG 302’ showed intermediate sensitivity to ethylene, while the cultivar ‘Calypso’ showed complete abscission of leaves when exposed to 10 µl of ethylene for 48 hours in both development stages. Plants treated with 1-MCP showed similar durability to control for both varieties and developmental stages, and the treatment with 1-MCP + ethylene was beneficial only for ‘MG 302’. STS was the most efficient substance in delaying the ethylene, wherein at stage 1 there was no leaf abscission and at stage 2 had much reduced leaf abscission occurred, regardless the cultivar. Treatment with STS + ethylene was efficient only at stage 1 for ‘Calypso’ and at stage 2 for ‘MG 302’. According to the data, cultivars showed different levels of sensitivity to ethylene, ‘Calypso’ is very sensitive and ‘MG 302’ showed intermediate sensitivity. Regardless the cultivar, STS treatment significantly blocked the ethylene action in both development stages and the use of 1-MCP was less efficient

Increase in DNA fragmentation and the role of ethylene and reactive oxygen species in petal senescence of Osmanthus fragrans

In sweet osmanthus (Osmanthus fragrans Lour.) flowers, petal browning, partial abscission and wilting are the visible symptoms of senescence, 4–5 days after flowering, which seriously affect its ornamental and economic value. In the present study, DNA fragmentation was used as a marker to investigate the role of ethylene and reactive oxygen species (ROS) in flower senescence of O. fragrans ‘Liuye Jingui’. In intact plants, nuclear shrinkage and DNA fragmentation occurred at the late full flowering stage when senescence symptoms became visible. This coincided with a rapid increase in ethylene production, ROS generation and lipid peroxidation. To further determine the role of ethylene and ROS in flower senescence, cut flowers were treated with ethephon, silver thiosulphate (STS), hydrogen peroxide (H2O2), and vitamin C (Vc). The vase life of cut flowers was significantly prolonged by 0.2mM STS and 2.5mM Vc treatments, but reduced by 0.03% H2O2 and 500mgL−1 ethephon treatments, compared to distilled water. The percentage of DNA fragmentation was dramatically increased by ethephon but reduced by STS treatment throughout vase life. In contrast, the dramatic increase of DNA fragmentation in the H2O2 treated samples was only observed at day three, and clear petal abscission and rapid petal wilting occurred only with ethephon. Compared with the distinguishable nuclei and complete vacuoles in both STS treatment and distilled water, ethephon treatment caused substantial damage to large central vacuoles and other organelles, and many petal cells twisted out of shape due to a loss of cytoplasm, resulting in rapid petal wilting. Thus, it is concluded that ethylene plays an important role in flower senescence of sweet osmanthus, enhancing DNA fragmentation, damaging cellular structure, and leading to petal abscission and wilting. In addition, ROS is also involved in the regulation of late DNA degradation and lipid peroxidation.

IMPROVEMENT OF VASE LIFE CUT GLADIOLUS FLOWERS BY ESSENTIAL OILS, SALICYLIC ACID AND SILVER THIOSULPHATE

Effects of the application of salicylic acid (SA) (1.5 mMol), ajowan and summer savory essential oils (500 and 1000 ppm), silver thiosulphate (STS) (150 ppm) and combinations of these materials on vase life of cut gladiolus flowers were investigated. Results of this study showed that within all treatments, SA treatment showed the best effect on the fresh weight (%), water uptake (cm3) and vase life of cut flowers. Moreover, it is showed that ajowan oil at 500 ppm concentration had benefit effect on fresh weight (%) and vase life of cut gladiolus and then STS treatment had positive effect on water uptake (cm3) of cut flowers. Key words: Cut gladiolus flower, essential oil, salicylic acid, silver thiosulphate, vase life.

Effects of Cold Storage and Different Pulsing Treatments on Postharvest Quality of Cut OT Lily 'Mantissa' Flowers

Effects of the pulsing solution containing silver thiosulphate (STS) or spermidine on postharvest quality of cut OT Lily ‘Mantissa’ (an Oriental x Trumpet hybrid) flowers were investigated. The application of spermidine prolonged the inflorescence longevity and improved the quality of cut flower of OT Lily ‘Mantissa’ in the same way as the STS treatment. The pulsing treatments reduced water dissipation, maintained membrane structure and function, and delayed the accumulation of malondialdehyde (MDA) and proline. The results indicate that spermidine can be used as a commercial preservation solution for cut lilies. Cold treatment reduced the vase life and lowered the quality of cut flower. The pulsing treatment containing anti–ethylene improved the postharvest quality, and the cold–stored cut flowers showed more improvements in the postharveat quality than the cut flowers without cold storage.

Use of silver thiosulphate (STS) and 1-methylcyclopropene (1-MCP) to improve the shelf life of miniature potted rose cv. Amore

The quality of miniature potted roses during their shelf life is limited by bud abscission and premature flower senescence. Rosa hybrida L. cv. Amore plants were pretreated with silver thiosulphate (STS) at 0.2 and 0.4 mM and with 1-methylcyclopropene (1-MCP) at 0.3, 0.5 and 0.7 g m-3 for 6 h in order to investigate the effects of these chemicals on the postharvest quality. Both chemicals extended the flower longevity as well as the plant display life compared with the untreated control. The best treatments in this respect were STS at 0.4 mM and 1-MCP at 0.5 g-3 for 6 h, which resulted in the least degradation in the chlorophyll content of the leaves. The treatment with STS at 0.4 mM increased the flower longevity and plant display life by 1 and 1.67 days, respectively, compared with the 1-MCP pretreatment at 0.5 g m-3. Since 1-MCP treatment does not have the heavy metal implications of STS treatment, the use of 1-MCP pretreatment for extending the shelf life of miniature potted rose cv. Amore was recommended.

Increasing flower longevity in Alstroemeria

The vase-life of Alstroemeria (cv. Rebecca) flowers is terminated when the tepals abscise. Abscission was accelerated by both chloroethylphosphonic acid (CEPA) and 1-aminocyclopropane-1-carboxylic acid (ACC). Petals abscised 24 h earlier compared with controls, when isolated cymes were placed in 340 nM CEPA, and earlier still when higher concentrations were used. This suggests that flowers of this Alstroemeria cultivar are very ethylene sensitive. Treatment with silver thiosulphate (STS) overcame the effects of exposure to CEPA and delayed perianth abscission of untreated isolated flowers by 3–4 days. The inclusion of 1% sucrose in the vase solution also extended longevity but not by as much as STS treatment; combined STS and sucrose treatments did not increase longevity beyond that of either treatment alone. However, removal of the young buds from the axil of the first flower was the most effective treatment to extend vase-life and encouraged the growth and development of the remaining flower. Flowers on cut inflorescences from which young axillary buds were trimmed more than doubled in fresh weight 6 days after flower opening compared with an increase of only 70–80% in those untreated or treated with STS and/or sucrose. Growth was less in isolated cymes but followed a similar pattern. The effect of STS and/or sucrose treatment was synergistic with the trimming treatment and thus the vase-life of trimmed, STS and sucrose-treated flowers was over 7 days longer than that for untreated controls.

MODULADORES DA BIOSSÍNTESE E DO MECANISMO DE AÇÃO DO ETILENO SOBRE O CRESCIMENTO IN VITRO DO PORTA-ENXERTO DE MACIEIRA MARUBAKAIDO

A utilização de frascos de cultura com tampas que dificultam trocas gasosas entre o ambiente interno e externo dos frascos resulta em aumento considerável na concentração interna de etileno nos frascos de cultura, o que freqüentemente ocasiona redução na taxa de multiplicação de material vegetal in vitro. A redução da concentração do etileno na atmosfera interna dos frascos de cultura, por meio de inibição da biossíntese, ou da inibição do seu mecanismo de ação, tem promovido o aumento na taxa de multiplicação, o que reduz o tempo e o custo de produção de mudas micropropagadas. Neste trabalho, objetivou-se aumentar a taxa de multiplicação in vitro para o porta-enxerto de macieira Marubakaido pelo uso de compostos conhecidos por inibir a biossíntese ou o mecanismo de ação do etileno. Segmentos nodais de Malus prunifolia cv Marubakaido cultivado in vitro foram inoculados em meio de cultura MS (MURASHIGE e SKOOG,1962) suplementado com 2,22 µM de Benzilaminopurina, e mantidos em sala de crescimento a 27 ± 2 ºC, fotoperíodo de 16 horas, Densidade de Fluxo de Radiação Fotossinteticamente Ativa (RFA) de 40 mmol.m -2 .s -1 e umidade relativa do ar de 75 ± 5%. AVG (L-a-(2-aminoetoxivinil-glicina), AIB (ácido a-aminoisobutírico), CoCl2 (dicloreto de cobalto), e os brassinoesteróides 28-HCTS (homoetilcastasterona) e 5F-HCTS (28-homoetil- 5-flúor-castasterona), compostos moduladores da biossíntese do etileno, além de STS (tiossulfato de prata) e 1-MCP (1-metilciclopropano), conhecidos inibidores do mecanismo de ação do etileno foram empregados neste estudo, pela adição à atmosfera interna do frasco de cultivo, no caso do 1-MCP, e de aplicação foliar, no caso dos brassinoesteróides, ou pela adição ao meio de cultura, no caso dos demais compostos químicos mencionados. As variáveis avaliadas foram: comprimento das partes aéreas e sua hierarquia; número de partes aéreas medindo 1,5 cm de comprimento ou mais e partes aéreas medindo menos de1,5 cm, com identificação de sua hierarquia; e taxa de multiplicação dos explantes (número de segmentos nodais e ápices caulinares, aptos a multiplicação in vitro). Os resultados obtidos mostraram que, dentre as variáveis avaliadas, o número de ramos principais < 1,5 cm apresentou aumento da ordem de 74% quando o AVG estava presente na concentração de 5 µM no meio de cultura . Para o CoCl 2 , houve redução significativa em todas as variáveis avaliadas. Nenhuma alteração significativa foi encontrada para comprimento de ramos, número de ramos laterais ou taxa de multiplicação quando o AIB estava presente no meio de cultura. Para os tratamentos com 1-MCP e STS, os resultados apontaram para redução na taxa de multiplicação do material vegetal. Dentre os brassinoesteróides testados, somente o 5F-HCTS apresentou respostas significativas. Aumento da ordem de 83% na taxa de multiplicação do ramo principal mostrou-se relacionado à dose de 1 µg.parte aérea -1 do 5F-HCTS, tendo também sido observada elevação da ordem de 52% no número de ramos laterais ³ 1,5 cm nesta dose de 5F-HCTS. Concluindo, o brassinoesteróide 5F-HCTS apresenta potencial para ser utilizado com o objetivo de aprimorar a técnica de propagação in vitro para o porta-enxerto de macieira Marubakaido.

Silver thiosulphate can considerably reduce leaf and fruit abscission caused by ethylene in Capsicum annuum ‘Janne’

SummaryThe pot plant Capsicum annuum ‘Janne’ is very sensitive to ethylene. Experiments were therefore conducted to see whether silver thiosulphate (STS) could prevent leaf and fruit abscission caused by ethylene and darkness. A phytotoxicological experiment with plants sprayed at different developmental stages with 0.05, 0.15, 0.45, 1.35 or 4.05 mM STS showed no damage and no developmental after-effects. The effect of STS on abscission was also investigated in a stress experiment, which consisted of two main treatments: darkness for 72 h at 20°C, without applied ethylene, and darkness of 72 h at 20°C with an ethylene concentration of 1.0 μl l–1. The STS treatments were given as sprays of 0.45 or 4.05 mM 1,11, or 21 d before the start of the darkness and ethylene stress treatments. The ethylene concentration of 1.0 μl I–1 on non-sprayed plants caused abscission of leaves, and of the green and maroon fruits, but the red fruits were unaffected. Treatment with 4.05 mM STS, 1 or 11 d before ethylene exposure, considerably reduced the ethylene induced abscission, with little effect of treatment 21 d before ethylene exposure. However, compared with the greenhouse environment control, spraying 1 d before ethylene exposure in darkness and high relative humidity caused leaf damage that appeared only after ethylene exposure.

Abscission of Flower Peduncles in Rose ( Rosa × hybrida) Plants and Evolution of Ethylene

Summary Ethylene evolution from decapitated rose ( Rosa × hybrida cv. Nubia) peduncles in planta and explants showed a climacteric pattern typical of abscising plant organs. The rate of ethylene evolution from nondecapitated explants was higher than that from decapitated ones and was the highest from separated flower buds. Local application of IAA at the site of bud removal postponed abscission of decapitated peduncles by 10 days in comparison with decapitated peduncles without IAA. The inhibition of abscission with IAA was accompanied by an earlier and higher rise in ethylene evolution and by yellowing of the peduncles; basal application of STS (silver thiosulphate) postponed the abscission of decapitated peduncles for a period longer than 6 weeks without any visible symptoms of senescence and was also associated with increased evolution of ethylene. Application of 1-aminocyclopropane-1-carboxylic acid (ACC) stimulated evolution of ethylene and promoted abscission of non-decapitated and decapitated peduncles, as well as of peduncles treated with IAA, but did not affect the STS-imposed inhibition of peduncle abscission. An extremely high rise in ethylene was measured without affecting abscission when STS and IAA treatments were combined. The role of auxin in context of the concept of «tissue sensitivity» to ethylene is discussed. A possible existence of two separate ethylene systems, one involved in regulation of flower bud development and the second in regulation of flower bud and leaf absiccion, is discussed.

Production of ethylene by tissues of tomato, pepper, French-bean and cucumber in response to infection by Botrytis cinerea

Ethylene production by detached leaves of tomato, pepper, bean and cucumber infected by Botrytis cinerea was much higher than that of noninfected leaves of the same hosts. Maximum production of ethylene was observed in leaves showing mild symptoms of the disease as compared with noninfected or completely infected leaves. The fungus produced negligible amounts of ethylene when grown on autoclaved leaves, with the exception of pepper leaves supplemented with methionine (0·14 nl g −1 h −1). Exogenously supplied ethylene induced 75–370% more necrosis than B. cinerea infections in all the crops. Applications of methionine increased necrosis to a lesser extent. Silver-thiosulphate (STS) at levels of 10 −4 and 10 −5 m, aminooxyacetic acid (AOA 10 −3 and 10 −4 m) and aminoethoxyvinylglycine (AVG 10 −3 and 10 −4 m) reduced the development of grey mould disease significantly. AOA and AVG inhibited the production of ethylene by all the crops. Disease incidence in cucumber fruits was increased by growth at 4 °C or treatment with ethephon prior to inoculation whereas STS treatments completely inhibited disease development. Disease development was also decreased in intact plants treated with the inhibitors.

Reversal of ethylene inhibition of tulip stem elongation by silver thiosulphate

Cut flowering stems of Tulipa cultivars were treated with a range of silver thiosulphate (STS) solutions (0.01–2.0 mM) for different times (10 min–24 h). The extension of the stem and longevity of the perianth were then observed at 18°C with the stems in water. At the highest dose (2.0 mM STS), a metallic silver sheen appeared on the surface of the STS solution and leaves were damaged. At non-toxic levels there appeared to be no effect on perianth longevity. However, the STS treatment completely reversed the inhibition of stem elongation caused by treatment with ethephon (48 mg l −1 for 24 h) or with ethylene (C 2H 4, 1 v.p.m. for 41 h). The results suggest that in spite of the lack of effect of STS on corolla longevity, the STS is freely mobile in the vascular tissue and in trace amounts blocks the effects of C 2H 4. Silver nitrate was not as effective as STS. Measurements of STS uptake suggest that about 1 μmol of silver is sufficient to counter the inhibitory effects of ethylene on stem elongation.