Alstroemeria Cut Flowers Research Articles

The effect of pre- and post-harvest sodium nitroprusside treatments on the physiological changes of cut Alstroemeria aurea ‘Orange Queen’ during vase life

Cut flowers deteriorate rapidly after harvest, lasting mere days. To extend their vase life, various postharvest techniques are employed. Due to limited knowledge about the postharvest physiology of Alstroemeria cut flowers and the specific role of secondary compounds and antioxidant systems in their protection, this study investigated the optimal dosage of sodium nitroprusside (SNP) as a nitric oxide (NO) donor to enhance quality and antioxidant defenses. Preharvest foliar application of SNP at 0, 50, 100, and 200 µM followed by short-term pulsing treatments upon harvest at the same concentrations were applied in a factorial design. Results revealed that a preharvest 100 µM SNP treatment combined with a 50 µM postharvest pulse significantly increased the total amount of phenols (over 20%), antioxidant capacity (more than doubled), and the activity of two antioxidant enzymes (ascorbate peroxidase by over 35% and guaiacol peroxidase by about 20%). Notably, this combination also diminished ion leakage (by about 20%), ultimately extending the vase life by more than 40% compared to untreated plants. Therefore, SNP application at these specific dosages proves effective in bolstering Alstroemeria cut flower quality and vase life through enhanced total phenols and a strengthened antioxidant system.

Multi-walled carbon nanotubes wrapped with polyvinylpyrrolidone can control the leaf yellowing of Alstroemeria cut flowers

The rapid yellowing of the leaves on cut flowers with leafy stems severely limits their vase life and commercial value. In this study, the effect of a composite of multi-walled carbon nanotubes (MWCNTs) and polyvinyl pyrrolidone (PVP) on the longevity of cut Alstroemeria flowers (Alstroemeria hybrida) was investigated to obtain a solution to this problem. A range of MWCNTs/PVP composite concentrations (0, 3, 6, and 9 mg L−1) was applied in a vase solution (for 24 h) as pulse treatments. Our findings indicate that the composite of MWCNTs and PVP exhibits excellent dispersibility in a vase solution. The results demonstrate that a 3 mg L−1 MWCNTs/PVP concentration was the most effective, extending the vase life of cut Alstroemeria flowers by up to 27 days. Pulsing with MWCNTs/PVP delayed the onset of floret abscission and leaf yellowing by 5 and 18 days, respectively. Additionally, when MWCNTs/PVP solution was applied to cut stems, water uptake remained consistently greater than that of the control. Additionally, MWCNTs/PVP increased the total chlorophyll content, soluble protein content, and POX enzyme activity of leaves while decreasing the malondialdehyde (MDA) content. The results indicate that this composite exhibited antimicrobial activity against gram-positive and -negative bacteria, particularly at a concentration of 3 mg L−1. This study demonstrated that adding MWCNTs/PVP to a vase solution of Alstroemeria cut flowers increased their longevity with minimal leaf yellowing symptoms compared to untreated cut stems. As a result, this nanocomposite can be used safely and effectively in vase solutions and in combination with other preservatives.

LED lighting strategies in cut flowers: balancing plant physiology and biological control of pests

Over the last decade, LED lighting has gained considerable interest as an energy efficient light source in greenhouse horticulture. Much work on LED lighting is done under controlled conditions in the absence of sun light, whereas the primary application lies in supplementation of low light conditions in winter. A frequently forgotten aspect herein is that spectral composition may also affect the biology of pests and their natural enemies, both directly and indirectly through an impact on induced plant resistance. In this paper, we present results of trials with chrysanthemum and alstroemeria cut flowers which were exposed to lighting regimes with varying contributions of blue, green, red and far-red light. These trials were done under low levels of natural light, mimicking winter conditions. In chrysanthemum, spectra where blue or green were added did not affect stem length, plant dry weight and number of flowers when the percentage of red light remained over 75%. Replacing part of the photosynthetically active radiation (PAR) light by far-red light considerably increased stem length and (in some species) plant dry weight, at the expense of flowering. In alstroemeria, the number of flowers harvested, their length and fresh weight was largest in the treatment with equal shares of blue, green, red and far-red light. In chrysanthemum, the beneficial insect Orius laevigatus was introduced and its egg-laying activity and population development under different lighting strategies was monitored. The number of eggs laid by the first Orius generation was affected by the percentage red light in the spectrum, with the lowest egg number found in plants grown under 95% red. The results for egg-laying by the second Orius generation differed among chrysanthemum cultivars. The implications of this work on lighting strategies for greenhouse horticulture are discussed, both in spectral composition and in timing during the day and the season.

Conservation of Alstroemeria cut flowers stored under refrigeration

Alstroemeria flowers have shown great importance in the world trade of cut flowers due mainly to its beauty and wide variety of colors. However, the durability of its inflorescences is usually hampered by the rapid yellowing of the leaves, which impairs their decorative quality. Cut flowers require the use of technologies to improve postharvest quality and floral longevity. This research aimed to study the postharvest conservation of inflorescences of Alstroemeria cv. Ajax at different storage temperatures. Floral stems were placed in containers with distilled water and stored at four temperatures (4, 8, 12, and 22ºC) for 12 days. The following analyses were performed: fresh mass variation, respiratory activity, relative water content, soluble and reducing carbohydrate contents, polyphenol-oxidase and peroxidase enzymes, pigments (anthocyanin and carotenoids), and longevity. The experiment was conducted in a completely randomized design, the results were submitted to analysis of variance (ANOVA), and the effect of treatments submitted to F-test. Significant differences were compared using the least significant difference (LSD) at 95% confidence interval (p ≤ 0. 05). The temperatures of 8 and 12ºC were effective in maintaining the postharvest quality of inflorescences during storage period, as they remained turgid due to transpiration reduction caused by low temperatures, and longevity reaching 46 and 22 days, respectively.

Effects of silver nanoparticles, chemical treatments and herbal essential oils on the vase life of cut alstroemeria (Alstroemeria‘Summer Sky’) flowers

ABSTRACTThe aim of this study was to investigate the effects of some chemical compounds on the post-harvest life of alstroemeria cut flowers. The experiment was conducted based on a completely randomized design with three replications. Treatments were: Nano-silver (1, 3, 5 and 10 mg l−1), salicylic acid (30, 50, 200 and 300 mg l−1), spermine (5, 10 and 20 mg l−1), essential oils of dill (5, 10, 50 and 100 mg l−1) and cumin (5, 10, 50 and 100 mg l−1) which were applied as pre-harvest, pulsing and continuous methods. These were selected on the basis of a literature review on the post-harvest life of different cut flowers. The evaluated traits were: the duration of vase life, destruction of carotenoids, peroxidase, ionic leakage of leaves and petals, enumeration and identification of bacteria in the vase solution. The most ideal condition of the traits was found for those flowers that were treated with 10 mg l−1 of Nano-silver prior to harvest. Also, salicylic acid, spermine and essential oils of cumin and dill had the desired effects. Additionally, 11 different colonies of bacteria such as E. coli, Enterobacter, Klebsiella, Proteus, Serratia, Citrobacter, and 5 others were identified.

EFFECT OF SILVER NANOPARTICLES, SPERMINE, SALICYLIC ACID AND ESSENTIAL OILS ON VASE LIFE OF Alstroemeria

In this study, effects of different concentrations of silver nanoparticles (NS), salicylic acid (SA), spermine (SP), dill (AN), and cumin (CM) essential oils are investigated on physiological and microbiological traits of alstroemeria (Alstroemeria hybrida) cut flowers during a preharvest and postharvest application. The study was performed as a factorial experiment based on a randomized completely design with three replications. During the experiment the vase life of cut flower was evaluated in terms of chlorophylls a, b and total, SOD, MDA, stem end bacterial colonies and bacterial identification. The results showed that using high concentrations of nanosilver (NS2) increased significantly the vase life of cut Alstroemeria in preharvest and postharvest. 11 colonies of bacteria were identified in stem end of cut alstroemeria flowers.

Effect of aminooxyacetic acid (AOA) on ACS and ACO genes expression and the vase life of alstroemeria cut flower

Aging in the limbs is divided into two categories: ethylene-sensitive limbs, and ethylene-insensitive limbs. Extracellular synthesis of ethylene in the first group is carried out through a specific biochemical pathway that results from flower development and pollination. The present study aims to explore the effects of aminooxyacetic acid (AOA) on the expression of ethylene biosynthesis pathway genes (1-aminocyclopropane-1- carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxidase (ACO)) and the vase life of the Alstroemeria cut flowers ‘Mayfair’ and ‘Frosty’ varieties. Also, the effect of AOA on at the rates of 0, 50, 100 and 150 mg/l was studied on the morphological and physiological traits. The comparison of the vase life of Mayfair and Frosty showed that Frosty had a longer vase life than Mayfair. Frosty exhibited lower levels of cell degradation, higher relative water content, more chlorophyll content, more total soluble solids, and higher peroxidase level than Mayfair. Higher AOA levels were significantly associated with higher activity of catalase and peroxidase, so that the 150 mg/l AOA had the greatest effect on the activity of these two enzymes. Also, the increase in AOArate to 150 mg/l resulted in the retention of leaf chlorophyll and the reduction of leaf chlorosis percentage in both studied varieties.The results indicated that the highest ACO and ACS gene transcripts were related to the 7th flower opening stage. The use of AOA was effective in reducing the gene expression in Frosty. Also, the application of 150 mg/l AOA had a significant reducing effect on the expression of the ACS gene in Frosty.

Postharvest conservation of alstroemeria ‘ajax’ using 1-methylcyclopropene

ABSTRACT Cut flowers deteriorate quickly and require postharvest technologies to increase their durability, which is usually around 8 days. Due to the scarce information related to postharvest physiology of Alstroemeria cut flowers, this study aimed to verify the best dose of 1-methylcyclopropene (1-MCP) to the postharvest conservation of inflorescences of Alstroemeria cv. Ajax, considering the factors associated with floral senescence and loss of the decorative life. The stems were submitted to four doses of 1-MCP (0; 100; 250; 500 ppb), then placed in containers with distilled water and stored at room temperature (22 ºC). The treatments were performed in triplicate containing three stems per replicate. The evaluations were performed every three days for a total of 12 days of storage. An F test was conducted, and the means were compared by the Tukey test (p≤0.05). Among the applied treatments the dose of 500 ppb of 1-MCP reduces the loss of water of the stems of alstroemerias during the storage period, keeping the petals turgids and the levels of carotenoids and anthocyanins high, however, this was not enough to keep the decorative quality of the flowers, once the 1-MCP did not solve the problems of yellowing of the leaves and floral openning, which are important characteristics for its commercialization.

Changes in postharvest physio-biochemical characterustics and antioxidant enzymes activity of cut alsteroemeria aurantiaca flower as affected by cycloheximide, coconut water and 6-benzyladenine

Early leaf yellowing in cut alstroemeria ( Alstroemeria aurantiaca ) flowers before flower development and petal abscission is an important limiting postharvest quality and vase life factors. Early leaf senescence reduces postharvest longevity of cut flowers and promotes petal's wilting. A study was made to evaluate the response of cut alstroemeria flowers at varying concentrations of cycloheximide (CHI) (50, 100 and 200 mg l -1 ), coconut water (5, 10 and 20%) and 6-benzyladenine (BA) (50, 100 and 200 mg l -1 ). CHI, coconut water and BA extended the vase life at all concentrations compared to the control, but coconut water at 5% concentration (with 17.39 days) was the most effective treatment. Control cut flowers showed the least vase life (10.76 days). Ethylene production in cut flowers promoted flower senescence. All concentrations of CHI, coconut water and BA delayed ethylene production compared to the control. Treatment of cut flowers with coconut water at concentration of 5% maintained the highest fresh weight of flowers and increased the content of water uptake. The chlorophyll degradation was significantly reduced by the application of CHI, coconut water and BA. The maximum content of membrane's lipid peroxidation and antioxidant enzymes activity (super oxide dismutase and peroxidase) was obtained in control cut flowers. Thus, 5% fresh coconut water has the potential to be applied as vase solution (preservative medium) due to prolongs of cut alstroemeria flowers.

Postharvest Longevity of Cut Gerbera and Alstroemeria as Affected by Citric Acid Pulse and Vase Solutions

End-user vase life of two popular cut flowers, gerbera (Gerbera jamesonii) and alstroemeria (Alstroemeria spp.) is limited due to non-adoption of appropriate postharvest treatments in Sri Lanka. Citric acid-based cut flower preservatives could be affordable treatments to extend the longevity of those species. Therefore, a study was carried out to investigate the effectiveness of pulse and vase solution treatments with citric acid for increasing the keeping quality of cut gerbera and alstroemeria flowers. For pulsing, cut flower stems were treated with 0 mM (distilled water), 5, 10 and 15 mM citric acid combined with 5, 16 and 24 h pulsing durations. Only alstroemeria was further tested with 0, 15, 25 and 30 mM citric acid with previous pulsing durations. Pulsed stems were stood into distilled water for vase life evaluation. For vase solution treatment, citric acid at 0, 1, 2, 5 and 10 mM concentrations were incorporated in vase water. In the next step, two levels of citric acid (0, 1 mM) were combined with four levels of sucrose (0, 1, 2, 5%) in vase water for gerbera. Factorial experiments were arranged in completely randomized design with five to ten replicates. Data on vase life, relative fresh weight and solution uptake rate were recorded. Pulse treatments were ineffective for improving vase life. Nevertheless, a vase solution with 1 mM citric acid showed a 2-fold increase in vase life and a better retention of fresh weight in cut gerbera. Incorporation of citric acid in vase water did not extend the vase life of cut alstroemeria flowers. Combining citric acid with sugar in the vase solution maintained favourable relative fresh weight, water uptake rates and vase life in cut gerbera. Thus, incorporation of 1 mM citric acid and 1 – 2 % sugar in vase or holding solutions could improve the longevity of cut gerbera flowers.

Potential of Increasing the Vase Life and Improvement of some Physiological Characteristics of Alstroemeria Cut Flowers by Using Non-Harmful Compounds Environmentally

In this study, the concentrations of 25, 375 and 500 ml L -1 of Cola+ 2000 mg L -1 of peppermint essence and concentrations of 30, 45 and 60 ml L -1 of apple extract +2000 mg L -1 rosemary essence on Alstroemeria cut flowers (Cv. balance) were investigated to verify the use of natural ingredients in flowers preservative solutions. This experiment was conducted in the laboratory of Gorgan University of Agricultural Sciences and Natural Resources, in 2014. Results showed that the interaction of cola with peppermint essence and apple extract with rosemary essence at above concentrations increase the vase life of flower, flower diameter and anthocyanin at significantly level of %1. The highest amount of vase life was related to concentration of 500 ml L -1 of cola (15 days), while vase life in control treatment (distilled water) was 9 days. The highest flower diameter was recorded in apple extract (45 ml L -1 ) + Rosemary essence (2000 mg L -1 ). The highest amount of anthocyanin was obtained in cola treatments of 500 ml L -1 + essence of peppermint, 30 and 45 ml L -1 of apple extract+ rosemary essence. Besides, flowers treated by 375 ml L -1 of cola + peppermint essence had the highest chlorophyll content. Generally, the results showed that treatments used in this experiment, as accessible compounds are healthy and non-hazardous for the environment, appropriate to increase the vase life of Alstroemeria cut flowers

Effects of chlorination and acidification on postharvest physiological properties of alstroemeria, cv. ‘Vanilla’ and on microbial contamination of vase solution

Leaf yellowing is the major postharvest crisis for cut alstroemeria flowers. Most studies have focused on hormone application to overcome this problem, while other important aspects of postharvest treatment such as vase solution microbial contamination and biocide effects have been ignored. Therefore, this study aims at evaluating the vase life and physiological performance of ‘Vanilla’ alstroemeria cut flowers in response to biocide application and microbial flora during postharvest handling. During two experiments flowers were treated with environmentally friendly and safe to use biocides such as citric acid (as acidifying agent) and sodium hypochlorite (as chlorination agent). Subsequently postharvest physiological parameters, namely vase life, side effect, weight change, solution uptake, chlorophyll content, and microbiological features of the vase solution such as microbial population, proliferation, and composition were studied. The results of the physiological study indicated a beneficial effect of chlorination on the vase life and most physiological parameters, especially chlorophyll content, and consequently, the green appearance of the leaves. Vase solution acidification, however, did not have a long lasting beneficial effect on physiological properties. Furthermore, microbiological studies show the efficacy of chlorination in reducing the vase solution microbial population and proliferation. By contrast, the vase solution acidification with citric acid was not able to control microbial proliferation. Microbial identification indicated Bacillus bacterial contamination as the dominant microbial vase solution flora.

Improving the Keeping Quality and Vase Life of Cut Alstroemeria Flowers by Pre and Post-harvest Salicylic Acid Treatments

Keeping quality and length of vase life are important factors for evaluation of cut flowers quality, for both domestic and export markets. Studding the effect of pre- and post-harvest salicylic acid applications on keeping quality and vase life of cut alstroemeria flowers during vase period is the approach taken. Aqueous solutions of salicylic acid at 0.0 (with distilled water), 1, 2 and 3 mM were sprayed to run-off (approximately 500 mL per plant), about two weeks before flowers harvest. The cut flowers were harvested in the early morning and both of cut flowers treated (sprayed) and untreated were kept in vase solutions containing salicylic acid at 0.0 (with distilled water), 1, 2 and 3 mM. Sucrose at 4% was added to all treatments as a base solution. The changes in relative fresh weight, water uptake, water loss, water balance, total chlorophyll content and vase life were estimated during vase period. The results showed that the relative fresh weight, water uptake, water balance, total chlorophyll content and vase life decreased significantly while the water loss increased significantly during experiment for all treatments. A significant difference between salicylic acid and control treatments in all measured parameters is observed. During vase period, the salicylic acid treatments maintained significantly a more favourable relative fresh weight, water uptake, water balance, total chlorophyll content and supressed significantly water loss, as compared to control treatment. Also, the results showed that the using salicylic acid increased significantly the vase life cut alstroemeria flowers, over control. The highest values of measured parameters were found when plants were treated by pre + post-harvest application of salicylic acid at 3 mM. The result revealed that the quality attributes and vase life of cut alstroemeria flowers were improved by the use of salicylic acid treatment.

A specific group of genes respond to cold dehydration stress in cut Alstroemeria flowers whereas ambient dehydration stress accelerates developmental senescence expression patterns.

Petal development and senescence entails a normally irreversible process. It starts with petal expansion and pigment production, and ends with nutrient remobilization and ultimately cell death. In many species this is accompanied by petal abscission. Post-harvest stress is an important factor in limiting petal longevity in cut flowers and accelerates some of the processes of senescence such as petal wilting and abscission. However, some of the effects of moderate stress in young flowers are reversible with appropriate treatments. Transcriptomic studies have shown that distinct gene sets are expressed during petal development and senescence. Despite this, the overlap in gene expression between developmental and stress-induced senescence in petals has not been fully investigated in any species. Here a custom-made cDNA microarray from Alstroemeria petals was used to investigate the overlap in gene expression between developmental changes (bud to first sign of senescence) and typical post-harvest stress treatments. Young flowers were stressed by cold or ambient temperatures without water followed by a recovery and rehydration period. Stressed flowers were still at the bud stage after stress treatments. Microarray analysis showed that ambient dehydration stress accelerates many of the changes in gene expression patterns that would normally occur during developmental senescence. However, a higher proportion of gene expression changes in response to cold stress were specific to this stimulus and not senescence related. The expression of 21 transcription factors was characterized, showing that overlapping sets of regulatory genes are activated during developmental senescence and by different stresses.

Effect of accel on the vase life and post harvest quality of alstroemeria (alstroemeria aurantiaca l.) cut flowers

Freshly cut flowering stems of Alstroemeria ‘Yellow King’ and ‘Marina’ were placed in glass jars containing solutions of Accel at 0, 25, 50, 75 and 100 mg/litre BA equivalent and arranged in a completely randomised design with 3 replicates. The effect of Accel on the vase life and qualityof Alstroemeria was investigated. Flowers held in Accel at 25 or 50 mg/litre BA equivalent consistently increased the number of days to full opening of primary florets and delayed the onset of flower senescence as measured by days to 50 % petal fall and days to 50 % leaf yellowing. Accel at 25mg/litre BA equivalent significantly increased the leaf nitrogen and chlorophyll content of Alstroemeria cut flowers. High Accel concentrations of 50, 75 and 100 mg/litre BA equivalent reduced significantly the leaf water content of Alstroemeria cut flowers. Accel at 75 and 100 mg/litre BA equivalentincreased leaf dry weight of Alstroemeria cut flowers. Our results indicate that Accel at 25 mg/litre BA equivalent has the potential to be used as a commercial cut flower preservative solution for delaying flower senescence, prolonging the vase life and enhancing post harvest quality of Alstroemeria cut flowers

Seed enhancement with cytokinins: changes in growth and grain yield in salt stressed wheat plants

Leaf yellowing is a major problem in Alstroemeria and absence of leaf senescence symptoms is an important quality attribute. Two Alstroemeria cultivars ‘Yellow King’ and ‘Marina’ were sourced from a commercial farm and harvested when sepals began to reflex. Stems were re-cut under water and kept in vase solutions of gibberellin A4+7 (0, 2.5, 5.0, 7.5, 10.0, 12.5 or 15.0 mg l−1 [Provide r ]). Treatments and cultivars were combined in a factorial fashion and arranged in a completely randomised design. Application of GA4+7 in the holding solution at 2.5–10.0 mg l−1 significantly delayed the onset of leaf senescence by around 7 days and significantly increased days to 50% petal fall by ca. 2 days. Additionally, these GA4+7 concentrations resulted in higher retention of leaf nitrogen, leaf chlorophyll and also increased leaf water content, while reducing leaf dry weight, all relative to untreated controls. Cultivar ‘Yellow King’ had significantly longer vase life and a better retention of leaf quality than ‘Marina’. Our results suggest that a concentration of 10 mg l−1 GA4+7 can be used to prolong vase life, delay leaf senescence and enhance post-harvest quality of Alstroemeria cut flowers during their transport to market.

Effect of Benzyladenine on the Vase Life and Keeping Quality of <i>Alstoemeria</i> Cut Flowers

Two experiments were conducted to investigate the response of Benzyladenine (BA) on the vase life and the physiological changes in the leaves of Alstroemeria cut flowers. The treatments were combined in a factorial manner and laid down in a completely randomised design with 3 replicates. Treatment of Alstroemeria cut flowers with 25 or 50 mg/litre BA consistently increased the number of days to full opening of primary florets and delayed the onset of flower senescence as measured by days to 50 % petal fall and 50 % leaf yellowing. BA at 25, 50 or 75 mg/litre increased both the leaf nitrogen and chlorophyll content of the Alstroemeria cut flowers compared to the control. However, 75 and 100 mg/litre BA gave the highest values of leaf dry weight. BA decreased the leaf water content of Alstroemeria cut flowers. These results suggests that 25 mg/litre BA has the potential to be used as a commercial cut flower preservative to prevent leaf yellowing and prolonging the vase life of Alstroemeria cut flowers . KEY WORDS: Alstroemeria , benzyladenine, post harvest quality, vase life J. agric. Sci. technol. Vol.5(1) 2003: 91-105

Effect of light and gibberellic acid on photosynthesis during leaf senescence of alstroemeria cut flowers.

The functioning of the photosynthetic apparatus during leaf senescence was investigated in alstroemeria cut flowers by a combination of gas‐exchange measurements and analysis of in vivo chlorophyll fluorescence. Chlorophyll loss in leaves of alstroemeria cut flowers is delayed by light and by a treatment of the cut flowers with gibberellic acid (GA3). The maximal photosynthesis of the leaves was approximately 6 μmol CO2 m−2 s−1 at I 350 μmol m−2 s−1 (PAR) which is relatively low for intact C3 leaves. Qualitatively the gas‐exchange rates followed the decline in chlorophyll content for the various treatments, i.e. light and GA3‐treatment delayed the decline in photosynthetic rates. However, when chlorophyll loss could not yet be observed in the leaves, photosynthetic rates were already strongly decreased. In vivo fluorescence measurements revealed that the decrease in CO2 uptake is (partly) due to a decreased electron flow through photosystem II. Furthermore, analysis of the fluorescence data showed a high nonphotochemical quenching under all experimental conditions, indicating that the consumption of reducing power in the Calvin cycle is very low. The chlorophyll, remaining after 9 days incubation of leaves with GA3 in the dark should be considered as a ‘cosmetic’ pigment without any function in the supply of assimilates to the flowers.

Effect of light and gibberellic acid on photosynthesis during leaf senescence of alstroemeria cut flowers

Effect of light and gibberellic acid on photosynthesis during leaf senescence of alstroemeria cut flowers

Role of other plant organs in gibberellic acid-induced delay of leaf senescence in alstroemeria cut flowers

Role of other plant organs in gibberellic acid-induced delay of leaf senescence in alstroemeria cut flowers