葉面噴施硝酸鈣提高無土栽培玫瑰產量、品質和瓶插壽命

摘要： 【目的】玫瑰（Rosa hybrida L.） 是全球范圍內廣泛栽培的觀賞花卉，花朵品質具有重要的商業價值。本研究旨在探討無土栽培系統中，葉面噴施硝酸鈣對兩個玫瑰品種（Samurai 和Jumilia） 品質和瓶插壽命的影響?！痉椒ā吭囼灢捎脽o土栽培方法，花盆中裝滿100% 珍珠巖（3～5 mm），以鈣含量減少50% 的霍格蘭營養液進行澆灌，供試玫瑰品種為Samurai 和Jumilia。培養4 個月，其中1 個月用于植株馴化，3 個月用于噴施處理。在培養第一個月后，噴施160 mg/kg 的硝酸鈣溶液，以不噴施硝酸鈣為對照。每個處理分別進行了3 次采收，每次采收后立即調查植株和花朵生長指標以及花朵瓶插壽命。【結果】葉面噴施鈣對玫瑰植株株高、花梗直徑、花冠大小、花朵特性和瓶插壽命產生了積極影響，而且這種影響隨采收次數的增加而增加。與Samurai 玫瑰相比，除瓶插壽命外，Jumilia 玫瑰各調查性狀的數值均普遍較低。在3 個采收階段中，鈣葉面噴施處理彌補了Samurai 和Jumilia 玫瑰各性狀的差異，特別是提升第3 個采收階段Jumilia 玫瑰花性狀的效果更為突出。與對照處理相比，鈣肥顯著提高了玫瑰葉片的光合速率和蒸騰速率?！窘Y論】葉面噴施硝酸鈣是促進玫瑰花生長，提升鮮切花產量、品質和瓶插壽命的有效措施。

關鍵詞： 鈣肥；葉面噴施；瓶插壽命；玫瑰；無土栽培

Rose （Rosa hybrida L.） is a beautiful and widelycultivated flowering plant belonging to the Rosaceaefamily. Rose is among the most beloved and popularflowers in the world because of its exquisite beauty，enticing fragrance， and symbolic significance[1]. Rose isnative to various regions of the Northern Hemisphere，including Europe， Asia， and North America[2]. Overcenturies of cultivation and hybridization， a vast array ofrose varieties has been developed， each with uniquecharacteristics and aesthetic appeal[3].

Roses， specifically Rosa hybrida L， require postharvestmanagement[4]. The quality， shelf life， and loss of thesedelicate flowers must be preserved by proper handlingand care after harvesting[5]. The overall quality of rosescan be maintained using storage[6]， handling with care[7]，packaging[8]， temperature control[9]， and hydration. Inaddition， plant nutrition can play a key role in improvingthe postharvest quality of flower[10]. Effective postharvestpractices， particularly improved nutrition status of plants，help reduce losses due to microbial contamination， rotting，wilting， and physical damage[4] leading to an increase inthe market value and customer satisfaction of flowers[11].In addition， the industry can facilitate international tradeand expand market opportunities by adhering to internationalquality standards and phytosanitary regulations.

Calcium （Ca） is an important nutrient element， andits significance in improving the qualitative characteristicsof rose-cut flowers has been widely reported[12]. Severalstudies have demonstrated that calcium improved thevase life of roses[13]. For example， it has been shown thatcalcium application in the form of nitrate results inhigher quality and shelf life of Rosa hybrida at thepostharvest stage[ 1 3 ] . Some reports indicate that Casupplementation reduces wilting or softening andinhibits the growth of fungal pathogens， such as Botrytiscinerea[14]. Calcium plays a role in the formation andstabilization of the pectin matrix， thereby enhancing thestructural integrity of the cell walls[15]. The positive roleof Ca nutrition in water uptake， extending vase life，longevity， and freshness of cut roses has also beenreported[16]. An important aspect of plant Ca nutrition isthe low efficiency of Ca supplementation， where it isadded to root media. The efficiency of Ca fertilizationlargely varies depending on the plant cultivar， source，and method of fertilizer application. Calcium is absorbedpassively by plant roots， and thus its root uptake and rootto-shoot transport are greatly affected by several factors，such as transpiration rate， temperature， and humidity ofthe surrounding environment， and competition withother cations[12]. Due to the low efficiency of Ca transportto low-transpiration plant organics， that is， flowers， theaddition of Ca to the root media is often ineffective inimproving flower Ca status[17]. Therefore， foliar applicationof Ca appears to be an effective approach for supplyingCa to low-transpiration organs. In foliar applications，nutrients are sprayed directly onto plant target organs，mainly the leaves[18]. This is a fast and efficient way to delivernutrients directly to plants[19]. Leaves absorb nutrients andtransport them throughout the plant[20].

Although the role of Ca in plant growth and postharvestquality of flowers in several ornamental plants has beenstudied， there is limited information on the effectivenessof foliar application of Ca from calcium nitrate on theyield and postharvest quality of different rose cultivars.In this study， the effects of foliar application of Ca fromcalcium nitrate on the yield， quality， and postharvest lifeof two rose varieties （Samurai and Jumilia） were investigatedin a soilless culture system.

1 Material and methods

1.1 Plant material and growth conditions

This experiment was carried out in a hydroponicgreenhouse at the Ferdowsi University of Mashhad，Mashhad， Iran， at a latitude of 36°29'72\"N and alongitude of 59°60'67\" E， and it is elevated at 995 m abovesea level. During the growing season， the greenhousecooling system consisted of a fan and a pad. The averagedaily temperature was 25°C， and the night temperaturewas （16±1）°C. The experiment spanned a duration of 4months， commencing in spring 2022， with 1 monthdedicated to plant acclimatization and 3 months for theapplication of treatments. Two rose varieties （Rosahybrida L.）， cvs. Samurai and Jumilia plants wereplanted in pots containing 100% perlite （3–5 mm）. Thefirst factor was rose varieties （cultivars Samurai andJumilia）， whereas the second factor was the harvest stage（stages 1， 2， and 3） （Table 1）， where stages 1， 2， and 3corresponded to the first， second， and third harvests ofeach treatment， respectively. The properties of thegrowing medium used in the experiments include highwater-holding capacity， low bulk density， adequateporosity， near-neutral pH， and balanced electricalconductivity， which provide ideal conditions for plantgrowth， as indicated in Table 2.

Transplanted plants were acquired from thegreenhouse of Mohammad Niya. Immediately aftertransplantation， the transplanted plants were grown fortesting. The flowers were irrigated for one week forrooting. In this study， a non-recyclable （open） hydroponicsystem was used. The nutrient solution was delivered tothe pots using a dripper irrigation system. Water volumeof 800 mL per plant was used throughout the experiment.The plants were then supplied with full Hoagland’snutrient solution for one month to adapt to greenhouseconditions. During this period， calcium nitrate was adjustedto approximately 50% of the required concentration toprevent nitrate from accumulation in the culture medium.One week before harvest， calcium nitrate （160 mg/L，cording to the Hoagland nutrient formula） was directlysprayed to plant leaves via a sprayer machine， as indicatedin Table 3. Tap water was used to prepare the nutrientsolutions， and the necessary amounts of nutrient elementsin the tap water were subtracted from the required levelsto formulate the Hoagland base solution， the concentrationsof nutrient elements present in the irrigation water wereCa2+ 249.456 mg/kg， Mg2+ 1.062 mg/kg， K+ 3.042 mg/kg，Cl? 22.40 mg/kg， SO42? 90 mg/kg.

1.2 Vegetative growth parameters

Flowers were harvested from spring after bloomsappeared， when the sepals had turned down and theflower became cylindrical. Stem length， stem diameter，flower length， flower diameter， pedicel length， pediceldiameter， corolla length， and corolla diameter weremeasured within a 3-month period. Flower stem heightand pedicle length were determined using a ruler. Thelength， flower diameter， corolla length， and corolladiameter were measured using digital caliper[12]. Leaf areawas recorded using a leaf area meter （WinArea_UT_10，Iran）.

1.3 Chlorophyll

Leaf SPAD values （at three stages after flowerharvest： 65， 80， and 95 days） and photosynthesisproperties were recorded using portable chlorophyllmeters （Li-Cor Li-3000， USA）[21].

1.4 Vase life

Vase life was determined by considering the timebetween flower cutting and the first signs of senescenceand wilting on the leaves and petals[22].

1.5 Statistical analysis

A split-plot design based on a completely randomizeddesign with two factors， that is， calcium fertilizer sourceand plant cultivar， was carried out in four replications.The first factor was rose varieties （Samurai and Jumilia），and the second factor was the number of harvests （1， 2，and 3）. Analysis of variance （ANOVA） was performedusing SAS 9.1.3 software （SAS Inc.， Carey NC）. Significantdifferences among means were determined at 0.05 level，according to Duncan’s multiple range test （MRT）.

2 Results and discussion

2.1 Stem length and diameter

Both stem length and diameter increased significantlyduring postharvest storage of Ca fertilizer-treated flowers（Fig. 1）. Earlier studies have reported that calciumfertilizer improves the quality of flowers and crops[4， 12， 23?25].Plant growth is enhanced by calcium sprays becausestems and flowers are always longer and larger [16， 23， 25]. Cais an essential element that enhances cellular hardnessand vigor. Additionally， the presence of Ca in the rootsoilsystem enhances the absorption and transport ofnutrients to the stems， ultimately resulting in better andstronger growth. Moreover， calcium plays a crucial rolein regulating crucial growth processes， and can affect therate at which cells grow and divide. Ca spray adjusts thecellular osmotic pressure and maintains a balancedosmotic pressure to improve the quality and dimensionsof plant stems and flowers.

2.2 Pedicel length and diameter

The results showed that foliar application of Caincreased the pedicel length and diameter of treatedSamurai and Jumilia roses compared to the control（Samurai and Jumilia without foliar application） at allharvesting stages. These factors also increased with theincrease of time （Fig. 2）.

There are several reasons why Ca spray improvespedicel length and diameter of rose flowers. Ca isan essential nutrient for plant growth that strengthenscell walls and promotes cell division[24， 26?27]. Plant tissuesreadily absorb Ca when sprayed[ 2 8 ] ， promoting cellelongation and structural integrity. Consequently， pedicelsare longer and stronger， allowing flowers to bear theirweight better. Furthermore， Ca contributes to overallgrowth by participating in various physiological processessuch as nutrient transport and enzyme activation. Caspray enhances rose flowers’pedicel length and diameterby promoting cell expansion， division， and nutrientuptake by positively influencing cell division and nutrientuptake.

2.3 Corolla length and diameter

The results showed that with foliar application ofCa， the corolla length and diameter of treated Samuraiand Jumilia roses increased compared to the control（Samurai and Jumilia without foliar application） in allharvesting stages. These factors also increased with theincrease of time （Fig. 3）. Foliar application of Ca to roseflowers increases corolla length and diameter because ofthe integral role of Ca in fundamental physiologicalprocesses， which can be attributed to the increaseobserved in corolla length. Plant cells rely on Ca as asecondary messenger for elongation and division[29].Spray application of calcium enhances the structuralintegrity and flexibility of the corolla cells by assimilatingCa into its tissues[24]. This leads to cell elongation andexpansion， leading to larger and stronger corollas. Inaddition， Ca facilitates the movement of essentialsubstances throughout the plant by facilitating enzymeactivation and nutrient transport. Because of thisenhanced nutrient availability， corolla cell growth wasfurther accelerated. These mechanisms enable Caspraying to increase both corolla length and diameter inrose flowers. This produces alluring and captivatingblooms.

2.4 Flower length and diameter

The results showed that foliar application of Casignificantly enhanced the flower length and diameter oftreated roses after harvesting compared with the controlat all sampling time points （60， 110， and 150 days）（Fig. 4）. There is a complex relationship between theextension of the appropriate exploitation time and theimprovement in the length and diameter of roses owingto Ca foliar application. Foliar application of Caimproves the uptake and transfer of nutrients to roseplants[23]. Ca can be added to soil or sprayed on leaves tomoderate environmental factors such as water transferstresses and weather conditions. As a result， flowersgrow more effectively. It is also important to select theappropriate harvest time to maximize rose flower lengthand diameter. At this stage of growth and development，the flowers reach their maximum size and quality. Themost suitable combination of foliar Ca application andthe right harvest time can increase cell growth， improvemetabolic processes， and enhance the length and diameterof roses.

2.5 Leaf number and area

The results showed that foliar application of Casignificantly enhanced the flower length of treated rosesafter harvesting compared to that of the control at allharvesting times （60 and 110 days）. In the third stage ofharvesting， the leaf number and leaf area decreasedsignificantly compared to those in the first and secondstages of harvesting （Fig. 5）. Foliar nutrient applicationand proper exploitation timing are responsible for theincrease in rose leaf number and area[30]. Ca applicationincreases the deposition of this nutrient in plants， resultingin improved cell and membrane structures and strength.This strengthening of the cellular structure increases theplant’s ability to transport water and nutrients to differentorgans， thereby increasing the number of leaves andimproving leaf area[17， 31]. In addition， this strengthening ofthe cell structure leads to an increase in the photosyntheticperformance of the leaves， and as a result， an increase inthe production of energy and organic compounds[32]. Inaddition， choosing a suitable time for exploitation alsoplays a vital role in improving the leaf number and areaof roses[33]. The plant is in the growth and developmentstages， during which it is actively growing. Plants havethe greatest capacity to absorb and accumulate nutrientsat this stage， which results in the optimal use of resourcesand energy. As a result， leaf number， leaf area， and cellvolume improved， and chemical compounds for leafgrowth increased. It is worth mentioning that thequantitative factors of Jumilia were lower than those ofSamurai were. This indicated a distinct response of thedifferent rose cultivars to calcium nitrate foliar spraying.In other words， the Samurai cultivar was more influencedby the calcium nitrate foliar spray than the Jumiliacultivar was.

2.6 Vase life

Vase life refers to the number of days between thecutting of flowers and the disappearance of theirornamental value[22]. The vase life of cut flowers plays animportant role in global marketing[34]. Generally， cut rosesdo not last long in vases， but their vase life will bereduced if they are subjected to water stress or botrytissymptoms[35]. Ca is one of the most vital elements in the cellwall and plays a major role in vase life[36]. The applicationof calcium fertilizer to suppress diseases and senescenceprolonged the vase life of cut flowers[37]. The resultsshowed that in stage 1 harvesting， the vase life of treatedSamurai rose with foliar application of Ca was increasedby 2.41 days more than that of the control （Samurai rosewith no foliar application of calcium）. In addition， thevase life of treated Jumilia rose with foliar application ofCa was increased by 2.62 days more than that of thecontrol （Jumilia rose with no foliar application of Ca）（Table 4）.

Physiological effects and biological processes relatedto plants and the storage environment increase the vaselife of roses as a result of foliar Ca application[38]. Similarresults have been reported by Ali et al[23] and Farahiet al [39]. Foliar Ca application strengthened cells and cellmembranes. These processes increase the strength andstructure of the plant and inhibit leaf evaporation ofmoisture[40]. Increased water and nutrient content offlowers， combined with appropriate harvesting times，can lead to an increase in antioxidant levels and extendthe shelf life of roses[41]. There may be differences inthe response to foliar Ca application and harvest timedepending on the type of rose. Plant structure andphysiological activities may have improved or changed，as well as environmental adaptation， to meet the needs ofdifferent species， leading to these differences. The geneticdiversity may have contributed to these differences.To increase flower longevity， the type of rose speciesshould also be considered when choosing foliar sprayingand operation time. This study emphasizes the benefitsof foliar spraying of calcium for growth and quality，highlighting its potential to enhance post harvest longevity.Harvest stage and cultivar differences also play a role inemphasizing species-specific considerations. Accordingto the results， there was a 22%， 26%， and 27% increasein post harvest longevity at stages 1， 2， and 3， respectively，for the Samurai cultivar compared with the correspondingcontrol treatment. Similarly， the Jumilia cultivar exhibitedan increase of 17%， 27%， and 25% in postharvest longevityat stages 1， 2， and 3， respectively， compared to thecorresponding control treatment. In essence， Ca， bybinding to lignin structures in the cell wall， thickensand strengthens it[42]. Consequently， an increase in themechanical strength of the stem leads to a reduction instem bending and an extension in the vase life of theflower.

2.7 Chlorophyll content index （SPAD value）

Table 5 presents the effect of Ca fertilizer on theSPAD and photosynthesis values of rosthroughout the study. The highest SPAD value （56.92）was observed in the T4 treatment （Jumilia with foliarapplication of calcium） at 95 days， which showed asignificant difference compared to all treatments. Thelowest SPAD values were obtained under T1 treatment（45.31） in the absence of calcium treatment. Overall， theresults showed an increase in SPAD values with stageacross all treatments， indicating that calcium fertilizerapplication positively affected the chlorophyll content ofrose flowers. The results showed that the effects ofdifferent treatments on the photosynthesis rate andtranspiration were significant. The photosynthesis ratewas the highest in the T4 treatment. The photosynthesisrate was the lowest in the T1 treatment. Transpirationincreased significantly with calcium fertilizer in alltreatments compared to that in the control treatments （T1and T2）， in which the lowest rate of transpiration wasobserved in T1 （Table 5）.e flowers

Various studies have reported an increase in thechlorophyll SPAD value of plants as a result of foliarcalcium application[43?45]. SPAD has previously beenattributed to the role of Ca in controlling cytoplasmicosmotic strength， which prevents the dehydration ofcells[45]. The observed increase in chlorophyll SPADvalues with foliar calcium application can be attributed toseveral factors. Calcium plays a crucial role in variousphysiological processes， including cell wall formation，enzyme activation， and nutrient transport[ 4 6 ] . Foliarapplication of calcium can promote better nutrient uptakeand transport within plants by enhancing cell membraneintegrity[47]. This improved nutrient transport facilitateschlorophyll synthesis， resulting in a higher chlorophyllconcentration[43?44]. Therefore， increased availability ofcalcium through foliar application contributes to theoverall health and vitality of rose plants. This resulted inhigher chlorophyll SPAD values and potentially morerobust and vibrant flowers.

It appears that increasing the amount of solublecalcium can change the regulation of stomata in such away that the opening of the stomata increases， whichincreases transpiration. Hu et al [48] reported that exogenouscalcium was more important for stabilizing the organelles’structure， regulating the osmotic balance， and increasingthe photosynthetic pigment content. This proved to beless important for stomatal opening and closing regulation.The extension of vase life was accompanied by an increasein photosynthesis， which was significantly enhanced inthe calcium nitrate foliar spray treatments comparedto the control treatment. This increase was 35% and 14%for the Samurai and Jumilia cultivars， respectively.Moreover， calcium increased leaf number， leading toan expansion of the photosynthetically active area.Consequently， the promotion of photosynthesis played arole in the enhancement of growth of the Jumilia andSamurai cultivars. This enhancement in photosynthesiscontributed to energy supply， resulting in increased stemlength， diameter， pedicel length， corolla dimensions，diameter， leaf number， area， and flower length of theroses. Consequently， the quality of the roses producedwas improved. This finding is in agreement with previousstudies regarding the effect of foliar application ofcalcium-tryptophan solution on increasing photosynthesisand consequently improving the growth of Brassicaoleracea seedlings[49]. The calcium present in chloroplastsplays a significant role in regulating the photosyntheticpathway， which serves as the primary source of energyfor plant cells[ 5 0 ] . Consequently， the improvementin photosynthesis due to Ca（NO3 ）2 treatment led tothe enhancement of growth parameters during thedevelopment of rose flowers.

3 Conclusions

This study evaluated the effects of foliar applicationof calcium fertilizer on the yield， quality， and postharvestlife of two rose varieties （Jumilia and Samurai）. Theresults highlighted the positive effects of calcium foliarapplication on growth and quality attributes， includingstem length， diameter， pedicel length， corolla dimensions，flower length and diameter， leaf number， area， and vaselife. As the harvest stages progressed， foliar sprayingwith calcium nitrate significantly improved the levels ofthese characteristics. Notably， the Jumilia quantitativefactors were lower than those of Samurai， except forflower vase life. Although the effect of calcium applicationon length values was not significant across stages， itinfluenced Jumilia in the third stage. In the calciumfertilizer treatments， photosynthesis rates increasedsignificantly compared to the control treatments. Likewise，transpiration rates increased significantly in all calciumfertilizer treatments compared to the control treatments.This study underscores the benefits of foliar calcium ongrowth and quality， noting its potential to extend postharvestlife. Harvest stage and varietal differences also play arole， emphasizing species-specific considerations. Thisstudy provides insights into optimizing rose productionquality and yield in soilless cultivation.