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Article

Control of Postharvest Performance of the Lilacs ‘Andenken an Ludwig Spaeth’ Induced to Flower in Spring

by
Ewa Skutnik
1,*,
Aleksandra Łukaszewska
1,
Diana Musiał
1,
Agnieszka Zawadzińska
2,
Piotr Salachna
2 and
Julita Rabiza-Świder
1
1
Section of Ornamental Plants, Institute of Horticultural Sciences, Warsaw University of Life Sciences, Nowoursynowska 166, 02-787 Warsaw, Poland
2
Department of Horticulture, West Pomeranian University of Technology in Szczecin, Słowackiego 17 Str., 71-434 Szczecin, Poland
*
Author to whom correspondence should be addressed.
Agriculture 2025, 15(18), 1940; https://doi.org/10.3390/agriculture15181940
Submission received: 18 August 2025 / Revised: 10 September 2025 / Accepted: 11 September 2025 / Published: 14 September 2025
(This article belongs to the Section Agricultural Product Quality and Safety)
Browse Figures
Versions Notes

Abstract

Common lilac (Syringa vulgaris) is an important cut flower on the flower market. The process of forcing shrub is crucial for lilac availability for floristry for six months of the year: from November to April. In this study, the vase life and certain biochemical processes occurring during senescence of cut lilacs ‘Andenken an Ludwig Spaeth’ induced to flower between March and May were investigated. Additionally, the effect of standard preservative (8-HQC + 2% S) and biocide (8-HQC) was analyzed. The vase life in water was relatively short (4 d), although it lengthened with the season and the standard preservative improved it. This solution enhanced florets’ fresh weight, water uptake, and transpiration rate, also caused an increase in the electroconductivity of the cell sap. Several other senescence-associated parameters such as carbohydrate, soluble protein and free proline contents were affected by the preservative whose effects were comparable to those found earlier in the winter forced lilacs. A highly efficient antioxidant enzyme system including catalase (CAT), peroxidases (POX) and superoxide dismutase (SOD) was present in developing inflorescences but the enzyme activity decreased in senescing florets. The hydrogen peroxide content and catalase activity were the highest in the biocide-treated flowers. Generally, in cut lilacs induced to bloom in April the changes in senescence-associated phenomena under study were occurring as in the flowers forced for November–December sales. Research shows the significant importance of sugar as a component of the cut flower preservatives whose use was essential for a proper bud development and good postharvest quality of cut lilacs.

1. Introduction

On the cut flower market, forced lilacs still hold an important position on the list of autumn–winter–spring flowering species. They are available for six months of the year if a grower/producer can release timely shrubs or cut branches from dormancy. In common lilac formation of generative buds begins in July and continues into autumn, after which the buds enter winter dormancy brought about by inner factors (endodormancy). Vegetation continues in spring when plants pass into the state of ecodormancy which depends only on the environmental conditions. Special treatments are necessary to overcome endodormancy in lilac so the procedure to obtain flowers in autumn/winter is called forcing [1,2]. For the earliest blooming date (November), shrubs have to be artificially cooled as the natural period of low temperatures outdoor is too short to release buds from dormancy or they are treated in a greenhouse with high temperatures of 35–37 °C. Such drastic conditions may damage flower buds on different levels (cytological, anatomical, morphological, biochemical, physiological) which was reported on the white cultivar ‘Mme Florent Stepman’ [3,4,5,6]. To make lilacs bloom in March/April, i.e., at a date much less distant from the natural flowering period is simpler, cheaper and safer. Plants do not have to be “forced” to flower as they have already been released from winter dormancy and no special treatments to break it are needed [7]. It is therefore a procedure aiming to accelerate blooming by creating the right environmental conditions which may be performed either in a greenhouse or outside for the soil-grown shrubs, using foil if needed. We introduce here the term “to accelerate” blooming to distinguish two procedures leading to the production of cut lilacs in the autumn/winter/spring period though we are aware that practically the term “to force” is commonly used in the production of lilac in all the above abnormal blooming dates.
The quality of the lilac inflorescences is determined by the date of forcing and the choice of cultivar. The earliest-flowering, white-flowered, single-flowered cultivar ‘Mme Florent Stepman’ is recommended for the November–December date. A good cultivar for early forcing is also white ‘Marie Legraye’. For January–March forcing, ‘Mme Lemoine’, with white, double flowers, and ‘Andenken an Ludwig Spaeth’, with single, lilac-blue flowers and long, narrow panicles, are recommended [8]. All the above-listed cultivars show the longest vase life when forced on their appropriate dates. Practically, only the cultivars ‘Mme Florent Stepman’ and ‘Andenken an Ludwig Spaeth’, are commercially forced in Poland, for the winter and spring period, respectively.
The quality of forced lilacs depends not only on growing conditions, but also on conditions after harvesting the flowers and it is water and carbohydrate availability which are decisive here. The concentration of endogenous total soluble sugars decreases in wilting lilac florets on stems held in water [7,9], while floral preservatives can significantly increase the longevity of cut lilac stems and promote sugar accumulation in petals [4,10]. Sucrose absorbed from a vase solution is broken down by the action of invertase and sucrose synthase, releasing glucose and fructose, causing their concentration to be increased in the rose flowers [11], which was confirmed also in studies on eustoma [12] and sweet pea [13]. Floral preservatives containing sugars, biocides and acidifying agents provide essential nutrients and inhibit microbial growth. Adding sugars to a vase solution provides an immediate source of energy for cut stems, which can promote better metabolic activity. Sucrose-containing solutions, in the range of 2% to 10%, can increase the vase life of lilac stems by providing the necessary carbohydrates to maintain cellular function and promote better hydration thus enabling flower opening [8]. Increasing the pool of energy compounds is an important aspect of ‘feeding’ cut flowers, because once they have been cut from the mother plant they no longer assimilate, and their vitality depends on reserves stored in the petals or supplied from the leaves and shoots [14]. As cut forced lilacs are devoid of foliage this extra supply of carbohydrates is especially important.
The longevity of cut flowers after harvesting is closely connected to their water balance, as the opening of the flower buds is not related to cell divisions in the petals, but depends on the free flow of water to them and the increase in the volume of already existing cells [15]. The water balance of cut flowers is mainly determined by water uptake and conduction in the shoot, transpiration, the ability to retain water in the cells of the perianth and the flower’s competition for water with other organs, especially under stress conditions [16,17].
Water uptake of cut flowers decreases primarily due to the appearance of obstructions in their vascular system [18,19,20]. A direct cause of blockage of conduction vessels is the presence of microorganisms [21,22], which multiply in the water and enter the vessels, limiting conduction and additionally secrete toxic metabolites, especially ethylene, which is dangerous for flowers, or enzymes that degrade cell walls [18,20]. Sometimes physiological xylem blockage occurs in cut flowers: it can appear even under sterile conditions and occurs in the part of the shoot above the water level in the vessel. It causes gums and gels to leak out of the shoot and enter the conductive vessels, limiting water uptake. In plants with woody shoots, polyphenolic compounds are primarily responsible for the physiological blockade, as the lignification process is accompanied by an increase in suberin, cutin and other metabolic substances [23]. Cutting of the lilac inflorescences stimulates as well the formation of tyloses (outgrowths of parenchyma cells) that effectively block water transport. The number of tyloses formed in the vessels of lilac shoots is related to the flowering date of the shrubs and the cut panicles longevity [20].
Water stress resulting from vessel obstructing hastens petal wilting leading to premature death. The onset of symptoms of petal cell death is preceded by rapid ion leakage due to disorganization of the cytoplasmic membranes and loss of their semi-permeable properties. Such parameters as electrical conductivity and pH are good indicators of perianth ageing and, by studying changes in their values, it is possible to predict the longevity of flowers after cutting what is used in practice in rose breeding [24].
The work aimed was to investigate changes occurring in spring (April) blooming lilacs and to compared them to the phenomena occurring in the winter forced lilacs. The effects of flower preservatives on their vase life were also checked. For practical (commercial) reason changes occurring during vase life were analyzed in the best cultivar recommended for the given blooming periods, i.e. ‘Andeken an Ludwig Spaeth’.

2. Materials and Methods

2.1. Plant Material

Lilac flowers were obtained from an ornamental plant producer near Warsaw. The inflorescences of the common lilac ‘Andeken an Ludwig Spaeth’ were cut from several-years old bushes forced in a plastic tunnel at five dates: the beginning and end of March, the beginning and end of April and the beginning of May. Shrubs grew in the ground soil and every other year in January they were covered with plastic tunnel and maintained at a temperature of 17–20 °C during the day and about 15 °C at night.
Flowering stems were cut early in the morning in the same developmental phase recommended by Greer and Dole [8] when a minimum of 1/3 of the florets in the inflorescence were open. After cutting, they were cooled at 2–3 °C for 12–24 h and transported to the Section of Ornamental Plants, SGGW. Cut lilac panicles were trimmed with a sharp knife to a length of 50 cm and placed into three solutions: distilled water (control), biocide 8-HQC (200 mg·dm−3 8-hydroxyquinoline citrate) or standard preservative 8-HQC + 2% S (200 mg·dm−3 8-hydroxyquinoline citrate with 2% sucrose). During the experiments, the solutions were not changed, only replenished when necessary. Each treatment for each date had 10 stems, individually tagged and treated as single replicates. All experiments were carried out in the phytotron under controlled thermal and light conditions (temperature of 20 ± 1 °C, relative humidity of 60%, quantum irradiance of 35 µmol·m−2·s−1, under the 12 h day/12 h night regime).

2.2. Vase Life, Flower Diameter and Weight

The longevity of lilac stems was determined in days and regarded as terminated when 30% of the florets in the inflorescence had the following symptoms: wilting, discolorating or browning.
The diameter of the florets in the inflorescence was measured at all harvest dates. Individual floret diameters were given as averages of two measurements taken in two perpendicular directions, carried out on d 4 in a vase life on 30 florets in each treatment, located at the lowest panicle level.
Florets were weighed on a laboratory scale, and their weight is shown as the average of 30 florets for each treatment and each date and given in mg fresh weight.

2.3. Electric Conductivity and pH of the Cell Sap

Cell electrolyte leakage was measured using the modified method of Whitlow et al. [25]. Ten 5 mm diameter discs were cut from florets harvested on d 0, 4 and 8, from upper and lower parts of the inflorescences and from all treatments, cut washed, dried and place in 10 mL of redistilled water and shaken for 24 h at room temperature. The conductivity and the pH of the cell sap were measured using a pH microcomputer with a conductivity metre (type CD-2, no. 700). The conductivity value was expressed as µS·cm−1.

2.4. Water Balance

Changes in the water balance of cut lilac stems were determined for inflorescences cut at the end of April. For each treatment, 10 stems were used. Each inflorescence was placed separately into cylinders, changes in fresh weight and solution uptake were measured daily and reported in gram (g). Transpiration was defined as the difference between water uptake and changes in inflorescence weight determined after replenishment of the solutions.

2.5. Biochemical Analyses

Material for all biochemical analyses was taken at three dates: day zero (on the day of setting up the experiment), 4 and 8 d after harvest, separately from the upper and lower panicles of lilacs accelerated at the end of April. For each analysis, samples were taken from 6 inflorescences in each treatment. Single florets (without calyxes) were detached, cut into small pieces, mixed, then three 0.5 g samples for each analysis were weighed and immediately placed in a deep-freezer at −82 °C.

2.6. Sugars, Soluble Protein, and Proline Contents

Analysis of total sugars was carried out according to the method of Dubois et al. [26]. Pre-frozen 0.5 g samples were homogenized in boiling 80% ethanol. To the alcoholic extract, 5% phenol and concentrated sulphuric acid (96% H2SO4) were added and mixed in a microshaker. After 20 min of incubation, extinction was measured with a spectrophotometer at 490 nm. The level of total sugars was read from a standard curve that was drawn up for glucose. Results were reported in mg glucose·g−1 dry weight (DW).
The reducing sugars content was determined according to Somogy method modified by Nelson [27] and given as g glucose on a DW basis. The plant material was homogenized in 80% ethanol. Copper reagent was added to the extract and incubated for 20 min in a water bath at 110 °C. After cooling, molybdenum-arsenic reagent was added and extinction at 520 nm was measured against a blank. The level of reducing sugars in the extract was read from a standard curve prepared for glucose.
The soluble protein content was determined by the method of Bradford [28], and expressed as mg per g on a DW basis.
The free proline content in lilac flowers was tested according to Bates et al. [29] by measuring the quantity of a coloured reaction product of proline with ninhydric acid. The absorbance was read at 520 nm. The amount of proline was calculated from a previously plotted standard curve and expressed in µmol·g−1 DW.

2.7. H2O2 Content

The hydrogen peroxide content of lilac flowers was measured spectrophotometrically after the reaction with potassium iodide (KI) as described by Jędrzejuk et al. [5] and expressed at 390 nm as µg of H2O2 per gram on a DW basis.

2.8. Assays of Antioxidant Enzymes

The catalase (CAT) activity (EC 1.11.1.6) was determined spectrophotometrically as the rate of hydrogen peroxide disappearance at 405 nm according to Goth [30] and expressed as mcatals per g of DW.
The activity of peroxidases (POX) (EC 1.11.1.7) was determined as described by Jędrzejuk et al. [5]. It was estimated spectrophotometrically at 430 nm and expressed in µmols of purpurogaline formed within 1 min per g of DW.
The superoxide dismutase (SOD) activity (EC 1.15.1.1) was determined as described by Giannopolitis and Ries [31]. Test tubes containing the reaction mixture and control tubes without the enzyme extract were kept in the dark for 20 min. at 25 °C. The change in the absorbance was recorded at 560 nm. The enzyme activity was calculated as a change in absorbance per minute and was taken as an equivalent of unit of the SOD activity at this wavelength per g of DW.

2.9. Statistical Analysis

The results were statistically processed using IBM SPSS Statistics 29 (PS Imago PRO 10.0), using the analysis of variance method (ANOVA 1, ANOVA 2). The averages obtained were compared with each other using the Duncan test, with a significance level of 5%.

3. Results

3.1. Flower Longevity, Flower Diameter, and Weight of Petals

Longevity of cut lilac inflorescences depended on the solution used and the forcing date. The highest average vase life of lilac panicles was at the latest flowering date (early May), more than double that of the earliest date (early March). The best vase life of lilac stems was recorded in May in standard preservative (8-HQC + 2% S), was 40% higher than in water, from this date. Lilac stems from the two dates—early March and early April—had the shortest vase life, ranging from 4.0 and 4.2 d in water to 6.1 and 6.3 d in standard preservative (Table 1).
Both solutions (8-HQC and 8-HQC + 2% S) and the date of forcing significantly increased the flower diameter in lilac panicles (Table 2). The diameter of individual flowers was the highest in the standard preservative irrespective of the date of forcing of the lilacs. The lowest values for flower diameter were recorded in lilac panicles placed in distilled water.
The average weight of florets taken from the lower parts of the panicles was the highest on the lilac shoots placed in the standard preservative and was 37% higher than in distilled water (Table 3). The highest mean floret weight was noticed in lilacs flowering in late April and early May. At each forcing date, floret weight was higher in lilacs placed in standard preservative, compared to petal weight of control (H2O) and biocide-treated lilacs (8-HQC).

3.2. Cell Sap Parameters

Changes in the electrical conductivity in lilac florets from the lower and upper part of panicle are shown in Table 4. Both, a holding solution and a sampling date significantly affected EC. In all the samples collected from the older (lower part) florets EC increased during vase life and the pattern of changes was similar: EC was the highest on the last sampling date. Its highest value was recorded in florets from stems kept in the preservative—more than double of the value determined in the freshly cut lilacs, significantly higher than in two other treatments.
Similar tendency occurred in changes in EC in upper florets (Table 4). In lilacs standing in water or 8-HQC the value was more than doubled relatively to the initial level while in stems kept in the preservative this increase was even significantly higher. Generally, the values of EC in lilac florets from particular treatments were comparable in the lower and upper panicle part.
The pH of cell sap of lilac florets ranged between 4.3 and 6.3 (Table 5). Generally, on all the sampling dates the values were higher in the older florets (lower raceme part) where the changes in pH were more pronounced than in the younger florets. There was no significant effect of a holding solution on the pH mean values. However, they were affected by the analysis date: pH increased on the second sampling date and dropped on the last one to a level comparable to that from fresh flowers.

3.3. Water Balance Changes

The uptake of solutions by cut lilac shoots depended on the treatments, as well as on the date of measurement (Figure 1A). A drastic decrease in uptake intensity was recorded in the control inflorescences, where it decreased by 54.1 mL over the course of the experiment compared to the first-day uptake date. The biocide solution reduced the decrease in uptake to 31.0 mL, and the 8-HQC + 2% S solution to 27.8 mL. The highest uptake in all dates was observed when inflorescences were placed into standard preservative; being more than 3- and 2.3-fold higher, than in water and biocide solution, respectively. On the last day (11), the uptake of lilac inflorescences from the 8-HQC + 2% S was 15 times higher than that placed in water and more than 3 times higher than in the 8-HQC solution.
The intensity of transpiration by cut lilac stems was dependent on the treatment and the date of measurement (Figure 1B). From the second day of the experiment, a decrease in transpiration was observed in lilacs placed in water. On the sixth day after harvest the shoots from this treatment transpired by 62% less than on the first day.
From the fourth day of the experiment onwards, lilac inflorescences placed in the biocide solution transpired more intensively than shoots from the control. This trend continued until the last day of the experiment, when the transpiration was more than two times higher than in control. In shoots standing in the 8-HQC + 2% S solution, the average transpiration was 2.8-fold and 2.3-fold higher than in the control and the biocide solution, respectively. On the second day, the highest transpiration in this treatment was recorded, and was 131% higher than in the control and 180% higher than in 8-HQC. The higher transpiration of the lilac shoots placed in the standard preservative persisted until the last measurement date, where transpiration was more than five times and five times higher than in shoots placed in water and 8-HQC solution, respectively.
Changes in fresh weight of cut lilac shoots accelerated at late April depended on the date of measurement and on the treatments applied (Figure 1C). A decrease in fresh shoot weight was observed in all treatments. Inflorescences placed in water showed the greatest average weight decrease (by 8.8 mg), while in 8-HQC + 2% S there was a decrease by only 5.6 mg. On the second day of the experiment, there was a decrease in fresh weight in the control lilacs, while the inflorescences placed into the biocide solution and standard preservative were characterized by an increase in fresh weight. A decrease in fresh weight by 4.4 mg was observed the lilac shoots placed in the biocide solution only on the last (11) day of the experiment, while in the control inflorescences such a decrease was already observed on the sixth day. The smallest decrease in fresh weight was observed in cut inflorescences placed in the standard preservative.

3.4. Sugars and Soluble Protein Contents

The total sugars content on the day of harvest in the lower part of the lilac panicles was 42% higher than in the upper part of the panicles (Table 6). On day 4, carbohydrate levels increased significantly in the upper part of the inflorescence in all treatments. In lilacs standing in standard preservative, the increase was almost 2-fold compared to the day of harvest. While on the same date the content of total sugars in the lower part of lilac panicles standing in the standard preservative increased only by 27%, and even less in flowers placed into water and biocide (about 2%). On the eighth day, the level of sugars in the upper part of the panicles decreased, but was still higher than on the harvest day. The same was in the lower part of the panicles, in flowers standing in the standard preservative the sugar level on day 8 was still 21% higher than on day 0. In the lower part of the panicles of lilacs standing in water and in the biocide solution, the pool of total sugars decreased compared to the initial content (day 0).
Analysis of the content of reducing sugars in cut lilac inflorescences showed a similar tendency (Table 7). Their level increased on day 4 in both, the upper and lower parts of lilac panicles, standing in water and the standard preservative compared to the initial content (day 0). On day 8, only in the lilacs standing in the standard preservative the content of reducing sugars was high; in the lower part of panicles, it was at a similar level as on the day of cutting and in the upper part of the panicles it was even 50% higher.
The average content of soluble proteins in both lower and upper flowers of lilacs forced in April was the highest on day 8 (Table 8). The increase was noticed in the lilacs standing in water and biocide solution, at the end of their life in the vase, they had a higher protein content than those immediately after cutting. On the contrary, it decreased in flowers placed in the standard preservative—by 28% and 46% compared to the initial value in flowers—lower and upper, respectively.

3.5. Free Proline Content

Both solutions used and the measurement date significantly affected the level of free proline in the lilac inflorescences (Table 9). In the lower flowers on stems standing in water, its level increased on the eighth day by almost 1/3, while it decreased by half on average in flowers from both solutions. In the upper flowers, the content of free proline decreased in flowers from all treatments, the most (3-fold) in lilacs placed into the standard preservative.

3.6. Hydrogen Peroxide Content

The average hydrogen peroxide content (Table 10) in cut lilac inflorescences decreased significantly in both lower and upper panicles (day 4 and 8), compared to the initial level (day 0). On day 8, the lowest H2O2 levels were recorded in the lilacs placed into the water, in the lower panicles it was almost half of the initial content and in the upper panicles it was even three times lower. The smallest decrease in hydrogen peroxide content was observed in the lower and upper part of the panicles of lilacs placed in a biocide solution (8-HQC), on day 4 it even increased slightly to decrease again on day 8 compared to the initial values.

3.7. Antioxidant Enzymes Activities

At the start of the experiment, the lower lilac flowers had 18% higher CAT activity compared to the upper flowers (Figure 2). During 8 d of the experiment, CAT activity decreased in flowers from all treatments, with the greatest decrease in the control flowers: 3-fold and 3.5-fold in the lower and the upper part, respectively. In flowers placed in the standard preservative, CAT activity decreased approximately 2-fold in the lower and upper flowers. In lilacs placed into the biocide solution these decreases were significantly smaller.
During the vase life of the lilac flowers, peroxidases activity decreased (Figure 3). The most drastic decrease occurred in flowers on stems placed in 8-HQC: 20 and 13.5 times in the lower and upper part, respectively. In the lower flowers from the standard preservative on day 8, the enzymes activity was 22% of the initial activity and 26% lower than in the control flowers. In the upper flowers on shoots placed in the standard preservative, the decrease in peroxidases activity was less and represented 58% of the initial value.
Changes in SOD activity in the lower flowers were similar in the control and in the standard preservative—after 8 d of flower vase life, there was a decrease of about 25%, while in flowers placed in the biocide solution—after a slight increase—SOD activity was maintained at the initial level (Figure 4). In the upper flowers in the control and in the standard preservative, there was an increase in enzyme activity—by 18% and 29% compared to the initial activity. In flowers placed in 8-HQC, the trend was the same as in the lower panicle: after an increase on day 4, there was a decrease in activity to the initial level.

4. Discussion

Lilac vase life varies from 4 to 12 d, depending on a cultivar, initial conditioning, and use of preservative and 5 d is a typical length of vase life for cut lilac stems [8,32]. The loss of vase life of cut lilac inflorescences is due to a number of factors. The tested purple cultivar ‘Andenken an Ludwig Spaeth’ cut in March and early April stood in water for only about 4 d (4.0–4.7), while already in late April it stood for 6.4 d and in early May for 9.9 d. Early forcing dates and high temperatures of forcing procedures significantly affect the postharvest life of lilac, especially of cultivars forced in November, as confirmed by Jędrzejuk’s and co-workers research on the white ‘Mme Florent Stepman’ cultivar [3,6]. Their vase life during this period was only 2.4 d in water and 6.8 in preservative solution (8-HQC + 2% S). But already with the alternative method of forcing at 15 °C (flowering in January), the lilacs stood in water for 9.2 d and in preservative for 12 d. This confirms how clearly the forcing temperature affects the longevity of flowers after harvesting.
To prolong this short vase life the preservative solutions can be used. The applied biocide, especially with the addition of sucrose, significantly prolonged the vase life of the cut lilacs ‘Andenken an Ludwig Spaeth’ on each of the forcing dates. The standard preservatives were particularly effective on the last dates of blooming A positive effect of exogenous sugar on postharvest vase life has been found for many cut flowers: rose [33], hydrangea [34], limonium [35] and peony [36]. This group of carbohydrates not only provides a substrate for respiration but also controls water balance in cut flowers. The sugar content of plant organs changes during their development and some organs, especially flowers, act as a sink.
When the stem is cut off, there is a reduction in the import of sucrose into the sink tissues of cut flowers [37]. The content of soluble sugars decreases in the petals as the flowers age, as the flowers usually no longer assimilate after cutting, but use their own reserves or exogenous sugar supplied with the preservative solution to the vase [38,39]. In the lilacs the contents of total sugars, including reducing sugars, decreased. Therefore, the use of sucrose in a vase solution had a significant effect on the physiological state of the flower tissues and endogenous sucrose levels. When placed in the standard preservative, they accumulated soluble carbohydrates in amounts sometimes up to twice as high as the control flowers standing in water. Younger lilac florets in the upper part of the inflorescence showed greater sink strength and accumulated more reducing sugars than older lower flowers. The phenomenon of sugar accumulation was not observed in lilac flowers placed in a biocide (8-HQC) only, due to the lack of sugars in this solution. This was also presented on the forced white lilac ‘Mme Florent Stepman’ [4]. In both cultivars the increase in the vase life of flowers placed into preservative solutions with sucrose was connected with increases in the diameter of the individual florets and their weight. Studies on lily also have shown that exogenous sucrose affects the longevity of cut flowers, due to increasing the endogenous carbohydrate pool [38]. The treatments with sugars promoted flower opening and extended vase life also in cut roses. The use of sucrose increases the concentration of glucose and fructose in the vacuole, which may reduce the osmotic potential of the symplast and increase water uptake, leading to cell enlargement during flower opening [33].
Water stress accelerates the senescence process of cut flowers, as water does not reach the inflorescence/florets in sufficient quantity due to the difficulties in transport through the stem. Flowers start to wilt when the fresh mass of the florets decreases due to the predominance of transpiration over water uptake. The results show that lilacs put into the standard preservative uptake significantly more solution from the vase than shoots put into water, which was directly translated into the vase life and floret opening. This confirms the important role of the undisturbed water uptake and transport towards the inflorescences in maintaining a good postharvest quality of cut lilacs.
However, on the based on the measurements and observations the conclusion is that the wilting of the lilacs does not appear to be related neither to the absolute amount of water uptake on the day of wilting, nor to the amount of water transpired at that point, or even to the fact that a positive water balance was maintained. In a previous study by Skutnik et al. [9], the holding solution (Chrysal Professional) which extended the longevity of the lilacs ‘Andenken an Ludwig Spaeth’ forced between March and April, in the vase from 5.2 d (water control) to 10.7 d, improved water balance parameters (fresh weight, water uptake and transpiration), delaying the appearance of negative water balance values. Also, in the white lilac cultivar ‘Mme Florent Stepman’ forced between December and March the uptake of preservative solution (Chrysal Professional 2 and 8-HQC 200 mg·dm−3 + sucrose 2%) was higher, what promoted flower opening and prolonged lilac vase life [40].
Flower senescence after cutting is strictly related to protein degradation [41]. In general, this relationship has been observed in many ornamental plant species during postharvest ageing, for example, in carnation [42], gladiolus [43] or dendrobium [44]. Sometimes the opposite happens, as observed by Zhao et al. [45] in cut peony flowers, where soluble protein content increased during the early vase life of the flowers and then decreased. In this experiment, an increase in soluble protein content in control lilac flowers and those placed in 8-HQC solution in both the lower and upper panicles was noticed. Only in flowers placed in the standard preservative a decrease in the protein content during inflorescence senescence was recorded, despite the higher longevity recorded in this treatment. In many species of plants, protein degradation and remobilization are mediated through protein ubiquitination and the action of specific proteases [46,47] transferring various amino acids to phloem. It is possible that some of the proteins decomposed into free amino acids were converted into sugars, essential for flower development and maintaining good postharvest vase life. Similarly, the white lilac flowers blooming at the natural May date had a significantly lower soluble protein content in open flowers in comparison to initial value in bud phases. While in the same white lilac cultivar forced in November under 37 °C at different stages of inflorescence development the protein content was at a similar, unchanged level [48]. It shows, how important the temperature during growth of lilac flowers is.
Accumulation of free proline is a characteristic change that takes place in plants under water stress conditions [49]. The content of this amino acid increases in stressed plants by up to several tens of times, which enables plants to function under unfavourable water stress conditions. Flowers are exposed to such stress after cutting. During their ageing, an increase in the level of free proline has been found [50], and vase life extension treatments have had the effect of reducing this phenomenon, as found, for example, in carnation by Yakimova at al. [51], and in cut lisianthus by Kazemi et al. [52]. There was an increase in free proline content in lilac inflorescences, but it was not as significant as that described in the literature. In lilacs placed in the standard preservative solution and in biocide solution in lower part of panicle, proline levels were generally lower than in control flowers. This suggests that the increase in proline content is a symptom of stress rather than an expression of adaptation to harsh conditions, since stress-reducing and flower-prolonging treatments reduce free proline levels in florets.
Durkin et al. [53] report that objective indicators useful for determining physicochemical changes in petal cut flowers are cell sap parameters, its pH and electroconductivity. Their research showed that from the time the cut roses (‘Sweet Promise’ and ‘Royalty’) were placed in the vase until they wilted, the values of these parameters kept increasing [54]. Similar changes in the cell sap and electrical conductivity values occurred during the lilac postharvest life. Here, almost 2-fold increase in electroconductivity was observed, resulting from changes in cytoplasmic membrane permeability. The holding solution did not limit this rise but affected the pH of the cell sap, in the upper part of inflorescences. These parameters are known and used as indicators of cut flower senescence, and often as predictors of their potential longevity [24] but in the case of lilacs flowers they have proven to be of little use.
Another cause of cut flower senescence is oxidative stress, which causes disruption of homeostasis. It results from an imbalance between the generation of reactive oxygen species and the antioxidant capacity in the plant [55]. Oxidative processes are accelerated by the increased water deficit in the plant, and result in the accumulation of large amounts of hydrogen peroxide, leading to cell damage [56]. In this study changes in the hydrogen peroxide contents were relatively small and senescing control flowers from the upper panicles contained less H2O2 than flowers placed into the standard preservative and biocide. Slightly higher amounts of this reactive oxygen species were in florets from the lower part of the panicles, but still much lower than on the day of harvesting. Such a relationship was confirmed by an earlier study by Jędrzejuk et al. [5] on the white cultivar ‘Mme Florent Stepman’. In the naturally flowering plants, the highest H2O2 content was reported in the open flower phase and the lowest in an unopen flower bud, while in the standard forced plants in November hydrogen peroxide level was more than 6 times higher than in florets from the naturally flowering shrubs in May in the same phase.
Plants have developed various protective mechanisms against the effects of oxidative stress in cut flowers. During the senescence of cut flowers antioxidant enzymes such as catalase, peroxidases and superoxide dismutase show increased activity [57]. Here, CAT and POX activities decreased with time in the lower and upper florets of all treatments, reaching values at the end of the vase life period lower than the initial values. This is most likely correlated with the level of hydrogen peroxide; the higher it is, the higher the activity of CAT and POX. The high activity of these enzymes, activated after harvesting due to the accumulation of hydrogen peroxide, reduced the level of this compound while simultaneously decreasing its own level. Similar observations were made by Jędrzejuk et al. [6] on a white cultivar ‘Mme Florent Stepman’ treated with the standard preservative and a solution with nanosilver (1 mg·L−1) and 2% S. These values for the activity of both enzymes decreased at subsequent stages of inflorescence development for the standard and alternative forcing method as well as at the natural May flowering date in all treatments.
In this study SOD activity decreased on subsequent dates in the lower, older parts of the lilac panicles. Research by Jedrzejuk et al. [5] shows the same pattern in standard November forcing when the drastic decrease started already from the flower opening stage. However, in the branches forced under 15 °C it increased above the initial value, similarly as in this experiment where at the end of vase life these values in the upper, younger parts of the inflorescences were higher than the initial ones. This shows that forcing lilac shrubs under low temperature better protects the antioxidant defence system thus delaying the senescence process.

5. Conclusions

The vase life of cut lilacs ‘Andenken an Ludwig Spaeth’ placed in water was affected by the date of forcing and increased with the season. The longevity also increased when lilac stems placed into a biocide solution (8-HQC) and especially standard preservative containing sucrose (8-HQC+ 2% S). It improved water transport so in shoots from the preservatives the intensity of solution uptake was higher, and its decrease was not observed until after 5 d. The cell sap pH of the flowers placed in water changed little during senescence and the standard preservative, while extending the vase life of the flowers, generally reduced the pH values. During flower senescence the total soluble and reducing sugar contents increased while the soluble protein and free proline contents decreased in flowers from the standard preservative. The hydrogen peroxide levels decreased during inflorescence senescence, reaching the lowest values in control flowers. The CAT, POX and SOD activities depended on the postharvest treatment and the stage of vase life. The results confirm the significant importance of sugar as a component of cut flower preservatives in bud development and longevity therefore the use of a sucrose-based solution and biocide (8-HQC) to maintain the vase life and quality of forced lilacs ‘Andenken an Ludwig Spaeth’ is recommended.

Author Contributions

E.S.: methodology, data curation, writing—original draft, oversaw the topic’s development; A.Ł.: writing—review and editing; D.M. and E.S.: investigation; J.R.-Ś.: contributed to refining the concepts, software; A.Z. and P.S.: resources; E.S. and J.R.-Ś. coordinated the structuring of the work, and finalized the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data is contained within the article. The data presented in this study are available in article.

Acknowledgments

The authors thank Warsaw University of Life Sciences for support in resources for research.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
8-HQC8-hydroxyquinoline citrate
CATcatalase
DWdry weight
KIpotassium iodide
POXperoxidases
Ssucrose
SODsuperoxide dismutase

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Agriculture 15 01940 g001
Figure 1. The effect of preservatives on water balance in cut common lilacs ‘Adenken an Ludwig Spaeth’ accelerated in late April. Water uptake (A), transpiration (B), and fresh weight (C) of cut lilacs flowers. Values are expressed as the mean ± SD. Vertical bars represent standard deviations of the means.
Figure 1. The effect of preservatives on water balance in cut common lilacs ‘Adenken an Ludwig Spaeth’ accelerated in late April. Water uptake (A), transpiration (B), and fresh weight (C) of cut lilacs flowers. Values are expressed as the mean ± SD. Vertical bars represent standard deviations of the means.
Agriculture 15 01940 g001
Agriculture 15 01940 g002
Figure 2. The effect of preservatives on changes on catalase activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
Figure 2. The effect of preservatives on changes on catalase activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
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Agriculture 15 01940 g003
Figure 3. The effect of preservatives on changes on peroxidases activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
Figure 3. The effect of preservatives on changes on peroxidases activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
Agriculture 15 01940 g003
Agriculture 15 01940 g004
Figure 4. The effect of preservatives on changes on superoxide dismutase activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
Figure 4. The effect of preservatives on changes on superoxide dismutase activity in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April. Means followed by the same letter do not differ significantly at α = 0.05 (Duncan’s test). Analyses were performed separately for upper and lower part of lilac inflorescences.
Agriculture 15 01940 g004
Table 1. The effect of forcing date and holding solutions on the vase life of cut common lilac inflorescences ‘Andenken an Ludwig Spaeth’.
Table 1. The effect of forcing date and holding solutions on the vase life of cut common lilac inflorescences ‘Andenken an Ludwig Spaeth’.
Forcing DateVase Life (Days)Mean for Date
H2O8-HQC8-HQC + 2% S
Early MarchA 4.2 a 15.2 b6.3 c5.2 A 2
Late MarchA 4.7 a10.6 c8.3 b7.9 B
Early AprilA 4.0 a5.5 b6.1 b5.2 A
Late AprilB 6.4 a8.9 b9.7 c8.3 B
Early MayC 9.9 a10.3 a13.9 b11.3 C
Mean for Treatment5.9 A 28.1 B8.8 B
1 Means followed by the same lowercase letter in each row and capital letter (in first column) do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for date and for treatment followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately.
Table 2. The effect of forcing date and holding solutions on the diameter of common lilac florets ‘Andenken an Ludwig Spaeth’ (on the 4 d experiment).
Table 2. The effect of forcing date and holding solutions on the diameter of common lilac florets ‘Andenken an Ludwig Spaeth’ (on the 4 d experiment).
Forcing DateFlorets Diameter (mm)Mean for Date
H2O8-HQC8-HQC + 2% S
Early March18.7 a 120.5 b21.4 b20.2 A 2
Late March19.4 a21.3 a23.2 b21.3 BC
Early April18.1 a21.2 b22.7 b20.7 AB
Late April19.9 a22.2 b23.8 b21.4 CD
Early May20.6 a21.1 a22.5 b22.0 D
Mean for Treatment19.3 A 221.2 B22.7 C
1 Means followed by the same lowercase letter in each row do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for date and for treatment followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately.
Table 3. The effect of forcing date and holding solutions on floret weight in common lilac florets ‘Andenken an Ludwig Spaeth’ (on the 4 d experiment).
Table 3. The effect of forcing date and holding solutions on floret weight in common lilac florets ‘Andenken an Ludwig Spaeth’ (on the 4 d experiment).
Forcing DateFloret Weight (mg)Mean for Date
H2O8-HQC8-HQC + 2% S
Early March25.4 a 126.8 b27.6 b26.6 A 2
Late March21.8 a27.5 b28.6 b26.0 A
Early April22.5 a25.8 b33.2 c27.2 A
Late April24.3 a27.3 b37.5 c29.7 B
Early May26.1 a27.1 a38.3 b30.5 B
Mean for Treatment24.0 A 226.9 B33.0 C
1 Means followed by the same lowercase letter in each row do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for date and treatment followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately.
Table 4. Electrical conductivity (EC) of cell sap in the inflorescences of common lilac ‘Andenken an Ludwig Spaeth’ accelerated in late April.
Table 4. Electrical conductivity (EC) of cell sap in the inflorescences of common lilac ‘Andenken an Ludwig Spaeth’ accelerated in late April.
TreatmentElectrical Conductivity [µS∙cm−1]Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O13.2 a 119.2 b27.9 d20.1 A 2
8-HQC13.2 a23.1 c27.2 d21.2 A
8-HQC + 2% S13.2 a24.4 c31.3 e23.0 B
Mean for Date13.2 A 222.2 B28.8 C
lower partH2O14.8 a 117.1 b20.3 c17.4 A 2
8-HQC14.8 a21.6 d24.2 e20.2 B
8-HQC + 2% S14.8 a23.2 e31.7 f23.2 C
Mean for Date14.8 A 220.6 B25.4 C
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 5. pH of cell sap in the inflorescences of common lilac ‘Andenken an Ludwig Spaeth’ accelerated in late April.
Table 5. pH of cell sap in the inflorescences of common lilac ‘Andenken an Ludwig Spaeth’ accelerated in late April.
TreatmentpHMean for Treatment
Day 0.Day 4.Day 8.
upper partH2O5.2 b 15.6 c5.4 b5.4 A 2
8-HQC5.2 b5.3 b5.4 b5.3 A
8-HQC + 2% S5.2 b5.9 c4.3 a5.1 A
Mean for Date5.2 A 25.6 B5.0 A
lower partH2O5.4 a 16.1 c5.9 c5.8 A 2
8-HQC5.4 a6.3 c5.6 b5.8 A
8-HQC + 2% S5.4 a5.6 b5.7 b5.6 A
Mean for Date5.4 A 26.0 C5.7 B
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 6. The effect of preservatives on changes in content of total soluble sugars in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
Table 6. The effect of preservatives on changes in content of total soluble sugars in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
TreatmentContent of Total Soluble Sugars [mg∙g−1 DW]Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O181.3 a 1263.4 d193.6 b212.8 A 2
8-HQC181.3 a282.2 e241.0 c234.9 B
8-HQC + 2% S181.3 a331.3 f243.7 c252.1 C
Mean for Date181.3 A 2292.4 C226.1 B
lower partH2O257.2 c 1263.4 d200.3 a240.3 A 2
8-HQC257.2 c261.9 d231.4 b259.6 B
8-HQC + 2% S257.2 c327.4 f311.1 e298.6 C
Mean for Date257.2 A 2284.2 B255.7 A
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 7. The effect of preservatives on changes in content of reducing sugars in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
Table 7. The effect of preservatives on changes in content of reducing sugars in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
TreatmentContent of Reducing Sugars [mg∙g−1 DW]Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O138.6 d 1204.7 e86.7 b143.3 B 2
8-HQC138.6 d134.5 c58.3 a110.5 A
8-HQC + 2% S138.6 d252.6 g214.4 f201.9 C
Mean for Date138.6 A 2197.3 B199.8 C
lower partH2O174.6 e 1190.6 f77.1 a147.4 B 2
8-HQC174.6 e128.7 c85.9 b129.7 A
8-HQC + 2% S174.6 e246.6 g166.5 d195.9 C
Mean for Date174.6 B 2188.6 C109.8 A
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 8. The effect of preservatives on changes in content of soluble protein in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
Table 8. The effect of preservatives on changes in content of soluble protein in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
TreatmentContent of Soluble Protein
[mg∙g−1 DW]		Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O11.9 c 18.2 b19.9 e13.3 B 2
8-HQC11.9 c13.3 d21.7 f15.6 C
8-HQC + 2% S11.9 c8.2 b5.2 a8.4 A
Mean for Date11.9 B 29.9 A15.6 C
lower partH2O10.7 c 111.1 c16.8 e12.9 B 2
8-HQC10.7 c15.2 d18.1 f14.7 C
8-HQC + 2% S10.7 c8.9 b7.7 a9.1 A
Mean for Date10.7 A 211.7 B14.2 C
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 9. The effect of preservatives on changes in content of free proline in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
Table 9. The effect of preservatives on changes in content of free proline in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
TreatmentContent of Free Proline [µmol∙g−1 DW]Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O14.6 e 110.7 c11.4 c12.2 B 2
8-HQC14.6 e13.4 d11.3 c13.1 C
8-HQC + 2% S14.6 e7.8 b4.8 a9.1 A
Mean for Date14.6 C 210.6 B9.2 A
lower partH2O13.4 e 113.5 e17.8 f14.9 B 2
8-HQC13.4 e9.7 d6.9 b10.0 A
8-HQC + 2% S13.4 e8.5 c5.6 a9.2 A
Mean for Date13.4 C 210.6 B10.1 A
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
Table 10. The effect of preservatives on changes in content of hydrogen peroxide in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
Table 10. The effect of preservatives on changes in content of hydrogen peroxide in the upper and lower part of the ‘Andenken an Ludwig Spaeth’ inflorescences accelerated in late April.
TreatmentContent of H2O2 [µg∙g−1 DW]Mean for Treatment
Day 0.Day 4.Day 8.
upper partH2O1104.4 c 1933.8 c334.5 a790.9 A 2
8-HQC1104.4 c1149.9 d656.9 b970.4 B
8-HQC + 2% S1104.4 c591.2 b630.5 b775.4 A
Mean for Date1104.4 C 2891.6 B540.6 A
lower partH2O1067.5 cd 1944.8 bc559.8 a857.4 B 2
8-HQC1067.5 cd1094.8 d841.5 b1001.3 C
8-HQC + 2% S1067.5 cd574.1 a656.6 a766.1 A
Mean for Date1067.5 C 2871.2 B686.0 A
1 Means followed by the same lowercase letter do not differ significantly at α = 0.05 (Duncan’s test). 2 Means for treatment and date followed by the same capital letter (2-way ANOVA) do not differ significantly at α = 0.05 (Duncan’s test), separately. Analyses were performed separately for upper and lower part of lilac inflorescences.
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MDPI and ACS Style

Skutnik, E.; Łukaszewska, A.; Musiał, D.; Zawadzińska, A.; Salachna, P.; Rabiza-Świder, J. Control of Postharvest Performance of the Lilacs ‘Andenken an Ludwig Spaeth’ Induced to Flower in Spring. Agriculture 2025, 15, 1940. https://doi.org/10.3390/agriculture15181940

AMA Style

Skutnik E, Łukaszewska A, Musiał D, Zawadzińska A, Salachna P, Rabiza-Świder J. Control of Postharvest Performance of the Lilacs ‘Andenken an Ludwig Spaeth’ Induced to Flower in Spring. Agriculture. 2025; 15(18):1940. https://doi.org/10.3390/agriculture15181940

Chicago/Turabian Style

Skutnik, Ewa, Aleksandra Łukaszewska, Diana Musiał, Agnieszka Zawadzińska, Piotr Salachna, and Julita Rabiza-Świder. 2025. "Control of Postharvest Performance of the Lilacs ‘Andenken an Ludwig Spaeth’ Induced to Flower in Spring" Agriculture 15, no. 18: 1940. https://doi.org/10.3390/agriculture15181940

APA Style

Skutnik, E., Łukaszewska, A., Musiał, D., Zawadzińska, A., Salachna, P., & Rabiza-Świder, J. (2025). Control of Postharvest Performance of the Lilacs ‘Andenken an Ludwig Spaeth’ Induced to Flower in Spring. Agriculture, 15(18), 1940. https://doi.org/10.3390/agriculture15181940

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