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Article

The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions

by
Cenk Küçükyumuk
1,*,
Zeliha Küçükyumuk
2,
Burhanettin İmrak
3 and
Songül Çömlekçioğlu
3
1
Vocational Training School, İzmir Demokrasi University, Park and Gardening Plants, Izmir 35140, Türkiye
2
Faculty of Agriculture, Department of Soil Science and Plant Nutrition, Isparta Applied Sciences University, Isparta 32000, Türkiye
3
Faculty of Agriculture, Horticulture Department, Çukurova University, Adana 01330, Türkiye
*
Author to whom correspondence should be addressed.
Horticulturae 2024, 10(11), 1217; https://doi.org/10.3390/horticulturae10111217
Submission received: 18 September 2024 / Revised: 27 October 2024 / Accepted: 12 November 2024 / Published: 18 November 2024
(This article belongs to the Special Issue Responses to Abiotic Stresses in Horticultural Crops—2nd Edition)
Browse Figures
Versions Notes

Abstract

:
This experiment was conducted at the Fruit Research Institute, MAREM, Eğirdir-Isparta, Turkey, to detect the effects of different glycine betaine doses in drought stress conditions on young pear trees in 2019. The pear trees used in the study were one-year-old Deveci (Pyrus Comminus L.) variety grafted onto OHxF 333 rootstock. There were three different irrigation treatments in the experiment. Treatments were I100 treatment—available soil water reached field capacity for each irrigation, 100% (control); I50 treatment—irrigated with 50% of the water used in the I100 treatment (50% water deficit, moderate stress); I25 treatment—irrigated with 25% of the water used in the I100 treatment (75% water deficit, severe stress). Four different GB doses were used: GB0: 0, control; GB1: 1 mg L−1; GB5: 5 mg L−1; and GB10: 10 mg L−1. GB was not applied to pear trees in the I100 treatment. That is, there were nine different treatments in this study. GB applications provided a 19% increase in Pn of both the I25 and I50 treatments. According to the results of gsw, gsw increased between 18.0% and 27.8% for GB50 and GB25 treatments, respectively. In total, 10.9% and 14.8% increasing rates in shoot length were detected in GB10 applications in both the 50% and 75% water deficit treatments. The highest trunk diameter and fresh root weight results were determined in 10 mg L−1 GB dose applications under 50% water deficit conditions (I50GB10).

1. Introduction

All over the world, agriculture, industry, and other sectors share fresh water. Agriculture production takes the most, with a 70% usage rate generally, and it exerts constant pressure on freshwater resources [1]. In recent years, it has been noted that extended droughts cause severe damage to several important crops in the main producing areas worldwide [2]. Drought stress is one of the most serious abiotic stresses limiting plant growth, development, health, and productivity [3,4]. Water deficits are responsible for the greatest crop losses, and they are expected to worsen. Water deficit is a critical abiotic factor that affects the growth and productivity of plants, especially in arid or semiarid regions of the planet [5]. This type of stress has become one of the main negative factors affecting agriculture productivity in many countries [6,7]. For this reason, many investigators have turned to trying to improve plant physiological immunity against stress [8]. When plants are exposed to drought stress, vegetative development reduces, and gas exchange and stomatal conductance decrease. Even if crop plants may exhibit tolerance to drought stress, they may not be as productive as desired in terms of crop production and quality [9].
We can generally define the factors that cause yield and quality losses as biotic and abiotic stress conditions in fruit growing. It has been reported that in many cultivated plants, yields can only be obtained at 50% of their genetic potential due to stress factors [10]. It is important to maintain water potential in plants through osmotic regulation [11]. Osmolytes are compatible solutes that accumulate rapidly in response to abiotic stress without interfering with other biochemical reactions in plants. Well-known organic osmolytes include proline, glycine betaine (GB), sugars, and polyols [12]. Osmoprotectants such as glycine betaine (GB) positively affect cellular osmotic regulation in many plants under environmental stress conditions [13]. The natural accumulation of GB in most plants is not at a level that can offset the negative effects of water loss that occurs due to many environmental stress factors [14]. The external application of GB to plants can increase tolerance, plant growth, and yield in various plant species against abiotic stresses. When GB is applied to the leaves of plants, it is easily absorbed by the leaf tissues [15]. Glycine betaine synthesis shows species-specific differences in plants under stress or no-stress conditions. It has been reported that plants are successful in managing stress with external glycine betaine applications in species with little or no synthesis [16,17,18,19,20]. Pear (Pyrus comminus) is among the species in which glycine betaine synthesis/accumulation is very low [21]. There are many studies on the effects of GB on plants growing but very few studies are on drought stress and GB on plant water consumption and other vegetative and generative parameters for fruit trees. Hozman (2016) reported that GB applications saved 38.3% of irrigation water in young chestnut trees [22]. GB applications in young olive trees saved 8.4% of irrigation water in treatments having full irrigation [23]. The reason for the differences in water saving percentage could be using different fruit tree species like chestnut and olive.
Fruits are important for agricultural production and also for human health. Pear is a fruit commonly cultivated after apple. According to the production yield data for 2022, total pear production is 26,426,373 tons, and Turkey is at fourth rank with an annual pear production of 551,086 tons [24]. To ensure commercial sustainability in pear production, water is one of the most important factors and countries especially under the threat of drought have begun to gain momentum in studies related to water stress [25]. It was aimed to determine the effects of using different levels of glycine betaine on physiological parameters and vegetative growth in pear trees under water deficit conditions in this study.

2. Materials and Methods

2.1. Experimental Area and Plant Material

The study was conducted in a semi-open and non-heated greenhouse on the experiment field at the Fruit Research Institute (920 m altitude, 37°49′18.24″ N, 30°52′22.90″ E, Eğirdir, Isparta-Turkey) in 2019. One-year-old Deveci (Pyrus Communis L.) pear variety grafted onto OHxF 333 rootstock was used in the study. Deveci variety was selected for this study since the variety is cultivated at a high rate in Turkey [26]. Trees were planted in pots in early April. The young trees are placed into a greenhouse with a clear plastic cover on the top, and the sides open in order to prevent the pots from being affected by the rainfall. We selected the pear trees having similar growth vigor before this experiment started.

2.2. The Mixed Soil and Irrigation Water

The mixed soil (15 L) of soil–peat–manure (1:1:0.5 ratios) was placed into 15 L pots before the experiment started. Irrigation water (EC = 0.3 dS m−1 and SAR = 1.04) was supplied from a well at the Fruit Research Institute. Irrigation water was classified according to the US Salinity Laboratory Graphical System. According to this system, the salinity values of the irrigation water, which are in the 250–750 EC × 106 range, are included in category C2, and in category S1 in terms of SAR value [27]. Irrigation water was C2S1 class, which is suitable for irrigation.

2.3. Irrigation and Glycine Betaine Treatments

There were three different irrigation treatments in the experiment. The treatments were I100 treatment—available soil water reached field capacity for each irrigation, 100% (control); I50 treatment—irrigated using 50% of the water used in the I100 treatment for each irrigation (50% water deficit, moderate stress); I25 treatment—irrigated using 25% of the water used in the I100 treatment for each irrigation (75% water deficit, severe stress). Four different GB doses were used: GB0: no GB, control; GB1: 1 mg L−1; GB5: 5 mg L−1 and GB10: 10 mg L−1. GB was applied to the leaves of all trees in liquid form by using a backpack sprayer. GB was not applied to the pear trees in the I100 treatment. That is, there were four different GB doses for each drought treatment (I50 and I25). The experiment was performed with a total of nine treatments (one control and eight treatments). Glycine betaine (GB) (pure chemical with Sigma brand code B2926, molecular formula C5H11NO2, molecular formula 117.15 g mol−1) was applied two times during the study: 1. on July 1st before starting water stress applications, 2. on July 15th after starting water stress applications.
The field capacity value of the mixed soil in the pots was determined in order to figure out the irrigation water amount used in every irrigation treatment. To calculate the field capacity value, the mixed soil in the five pots without plants was saturated with water before the study started. Then, the pots were covered with aluminum foil to prevent evaporation. The pot weight was considered as field capacity when no leaking was observed from the pots. The pots in the I100 treatment were weighed before each irrigation, and the depleted water from field capacity was applied to the pots with a pail (2 L volume and 50 mL accuracy) as the net amount of irrigation water. To calculate the amount of water used in the other treatments, the average water amount used in the first treatment was taken into consideration. The irrigation water that leaked into the base plate was added back into the pots. After July 1st, for each irrigation, 50% and 25% of the irrigation water amounts applied to the I100 treatment were calculated. Then, the calculated amounts were applied to the I50 and I25 treatments. The irrigation water that leaked into the base plate was added back into the pots. Irrigation water was applied until so that the soil water level reached field capacity for all trees in each irrigation from the planting date to 1 July. The water stress treatments were started on 1 July when the temperatures were higher and finished on 6 September. Irrigation interval was considered as four days during the experiment.

2.4. Plant Water Consumption

Irrigation water was applied to reach the available water up to field capacity in each irrigation until programmed irrigations started (2 July). Therefore, irrigation water amounts were considered as plant water consumption. After the programmed irrigations started, the plant water consumption was calculated for 10-day periods and Equation (1) was used.
ET10 days= T1 + I − T2
In Equality (1),
ET10 days = 10-day period plant water consumption (g);
T1 = Previous weight of pot (g);
I = The water amount applied between two weight measurements (g);
T2 = The weight of pot at the last weighing (g).
The plant water consumption values calculated in weight were converted to volume and expressed as l plant−1.

2.5. Photosynthetic Rate (Pn), Stomatal Conductance (gsw), and Transpiration Rate (Tr)

Li-Cor 6800 Photosynthesis System (LI-6800XT Portable Photosynthesis System, LI-COR Environmental, Lincoln, NE, USA) was used to measure the plant photosynthetic rate (Pn), stomatal conductance (gsw), and transpiration rate (Tr). All the parameters were measured three times after starting the water stress treatments (July 15th, August 12th, and September 6th). One tree was selected from each replication for measurements. Three totally different pear trees were used for all the measurements from each treatment. The leaves were used from the sun-exposed mature leaves of one-year-old shoots from different sides of the selected trees in each treatment. At least 3 leaves per plant were sampled between 11:00 and 14:00 on the day before irrigations. The measurement conditions were leaf chamber PAR (photosynthetically active radiation), 1100 μmol m−2 s−1; leaf-to-air vapor deficit pressure, 1.6–2.7 kPa; and chamber CO2 concentration, 400 μmol mol−1.

2.6. Vegetative Growth Parameters

Trunk diameter: Trunk diameter was measured three times after the initiation of the water stress treatments by using a digital caliper. Trunk diameter was measured on east–west and north–south at 15 cm upper level from the grafted point. The average of their values was calculated and considered as the trunk diameter.
Fresh root weight: Root pruning was performed equally on all the young pear trees before planting during the experiment establishment phase. In order to clearly determine the effect of water stress applications on plant weight values, all the trees were weighed by cutting their tops from the same point just before starting the study, and trees with weight values close to each other were selected. The young pear trees were removed from the pots by careful leaching at the end of the season. Then, fresh root weight under the scion area was determined by using a precise scale (±1.0 g).
Shoot length: All th eshoots were measured in cm with a measuring tape on all the trees used in this experiment at the end of the growing season.

2.7. Experimental Design and Statistical Analysis

The experiment was designed as a split plot. There were three replications for each treatment and each replication had three trees. The analysis of variance (ANOVA) test was calculated with the JMP software (JMP 8.0) [28] for the data. The differences among treatments were compared by using the LSD test.

3. Results

3.1. Plant Water Consumption (ET, Evapotranspiration)

Plant water consumption ranged between 25.1 L (I25-GB0) and 54.2 L (I100-GB0 control treatment) (Table 1). As GB rates increased, water consumption increased. The 10-day water consumption is presented in Figure 1. Water consumption values of the I25 treatments for all the GB rates decreased after the water stress application date (July 2nd) depending on the applied irrigation water amounts. Just after starting the drought stress applications (July 1st), ET values decreased for all the treatments except I100.

3.2. Photosynthetic Rate (Pn), Stomatal Conductance (gsw), and Transpiration Rate (Tr)

Figure 2 shows fluctuations in Pn values after beginning the water deficit applications. All the Pn values in the water deficit treatments decreased up to the end of the growing season. Statistical analysis was performed in the last Pn, gsw, and Tr measurements (6 September) (Table 2). GB rates positively affected the Pn, gsw, and Tr measurements. The highest Pn was determined in I50-GB10 with 10.06 μmol m−2 s−1, and I25-GB0 provided the lowest result with 7.55 μmol m−2 s−1. The treatments having 75% water deficit with no GB and 1% GB applications provided the lowest Pn results. The gsw was measured three times during the growing period (Figure 3). All the gsw results of the young pear trees showed fluctuations. The last gsw measurements (6 September) were made for statistical analysis. The I100 treatment having no GB application provided the highest gsw result (0.189 mol m−2 s−1). Increasing GB dose applications (GB5: 5 mg L−1 and GB10: 10 mg L−1) were not significantly different. The Tr results had a similar trend with Pn and gsw. Tr was at the highest level in the middle of the growing season (August) with 5.85 mmol H2O m−2 s−1. Tr increased until the middle of the growing season in I100 (no drought stress) but it was in a trend of decreasing near the end of the growing season. The other treatments that applied 50% and 75% water deficit were in a trend of decreasing the whole season. The lowest Tr results were determined in I25GB0 and I25GB1 with 3.78 and 3.80 mmol H2O m−2 s−1, respectively. Statistical analysis was carried out for each drought treatment and GB dose on Pn, gsw, and Tr. The drought treatments had an important effect on all the physiological parameters measured in this study. There was no significant difference according to GB doses (Figure 4).

3.3. Vegetative Parameters

3.3.1. Trunk Diameter

Trunk diameter increased in all the young pear trees during the growing period, but the rates of increase were limited by water deficit and GB dose applications (Table 3 and Figure 5). Different water deficit rates and GB doses had different effects on trunk diameter values (p < 0.01). The highest trunk diameter was determined in no water deficit treatment. The I50 and I25 treatments with no GB dose and 50% water deficit treatment with 1 mg L−1 GB provided the lowest trunk diameter. Trunk growth increased after the water deficit was applied on July 1st in all the treatments. GB10 and GB5 applications in 50% water deficit treatment (I50) provided the highest increasing rates, 17.5% and 14.2%, respectively. Statistical analysis was performed for each drought treatment and GB dose on trunk diameter, fresh root weight, and shoot length. Drought treatments had an important effect on all the physiological parameters measured in this study. There was no significant difference according to GB doses.

3.3.2. Fresh Root Weight

There were no significant differences between I50 treatments except GB10 application (Table 4). In the 75% water deficit treatment (I25), the 5 and 10 mg L−1 treatments were in similar statistical groups. Under 75% water deficit conditions, 5 mg L−1 (GB5) and 10 mg L−1 (GB10) GB doses had a similar effect on fresh root weight. The 10 mg L−1 dose application was the most effective treatment in the 50% water deficit application (I50-GB10). All the GB doses applied in the I25 treatments were lower than in the I50 treatments (Figure 6).

3.3.3. Shoot Length

Different water deficit applications and GB doses affected shoot length (* p < 0.05). GB5 and GB10 applications in the 50% water deficit treatments provided the highest shoot length in the water deficit treatments (Table 5). Shoot length increased for all the young pear trees during the growing season although a water deficit was applied (Figure 6). Increasing rates ranged from 10.5% to 65.8%. The effects of GB doses in the I25 treatment were similar on shoot development.

4. Discussion

GB applications increased ET in the presence of water deficit conditions. When trees are healthy, they can use more irrigation water, and their ET increase. GB applications provided more vegetative growth although a water deficit was applied, and so the increasing growth caused more ET. It means that GB can be used for young pear trees in water-restricted areas. GB application to olive trees provided water saving according to treatments with no applied GB applications [29]. Water saving was not obtained in this study. The reason for this result may be that vegetative growth increased in each GB application even if a water deficit was applied.
Photosynthetic productivity is an important physiological parameter, and it has been widely used to evaluate plant growth vigor [23,30]. The photosynthetic rate (Pn) is one of these parameters [31,32]. Except for the no deficit treatment, all the treatments were negatively affected by water deficit although different GB doses were applied to the pear trees. Drought can cause a significant reduction and damage in photosynthesis [33,34]. The results provided by no GB dose and 1% GB dose treatments were in similar statistical groups. It can be said that 1% GB application in 50% and 75% water deficit treatments had no positive effects on the young pear trees when considering the Pn results. GB5 and GB10 applications increased photosynthetic rates in treatments having 50% and 75% water deficit applications. Glycine betaine with 10 mg L−1 provided the highest Pn results among all the water deficit applications. GB applications had a positive effect on Pn in young olive trees under drought stress [35]. GB can provide tolerance to abiotic stresses even at low concentrations by protecting photosynthesis under abiotic stress [16,36]. Treatments having no GB had the lowest Pn results when compared to other GB dose applications. Using a GB dose of up to 20 mM L−1 increased Pn in mustard [37]. After these doses threshold, Pn did not increase. Since the highest results were provided from 10 mg L−1 GB applications, a higher dose than 10 mg L−1 GB should be used on pear trees in future studies. The extent of drought resistance by GB application largely varies depending on the crop species, growth stages, stress duration, and treatment concentration [38]. Different studies have reported that GB demonstrated encouraging effects on the improvement and growth of several plants in stressed conditions. Glycine betaine shields photosynthetic pigments and chlorophyll contents, which ultimately results in improved plant growth. GB boosts the Pn activity, enhancing the photosynthetic activities and synthesis of chlorophyll [39,40]. A number of studies reported that the application of GB increased photosynthesis rate [37,41,42]. Similar results were obtained by Tasuku et al. [43] and Abbas et al. [44] which revealed that the foliar application of glycine betaine improved the vegetative growth of eggplant and barley, and this improvement may be due to the role of glycine betaine in enhancing photosynthetic rate and stomatal conductance.
When considering GB doses applied at a similar water deficit rate, increased GB doses provided higher photosynthetic rate and stomatal conductance. When the plants are exposed to drought stress, firstly they narrow or close their stomatas in order to prevent water loss [45]. Stomatal conductance decreases when soil water decreases around the effective root zone. The reasons for this decrease are the closing of stomata and limited gas exchange [46,47]. Stomatal conductance increased in grapes with increasing GB doses. The 10 mg L−1 GB dose applications in both water deficit treatments (I50 and I25) also reduced the effect of decreases in stomatal conductance due to water deficit [48]. Closing the stomata reduces transpiration and gas exchange, which also causes a decrease in photosynthesis [49]. Drought stress and GB doses were considered as different factors, and statistical analyses were performed accordingly (Table 2). GB doses had no effect on Pn, gsw, and Tr data according to the statistical analysis. The reason why GB doses were found to be statistically insignificant in these data was that GB dose was not applied in I100. GB was effective on all the physiologic parameters when it was applied in drought stress conditions. These results show that GB shows its effect under drought stress conditions.
Increasing GB doses increased the trunk diameter of the pear trees which were in similar water deficit rates. The GB5 (5 mg L−1) and GB10 (10 mg L−1) applications provided higher trunk diameters when comparing the GB1 (1 mg L−1) dose. It means that a 1 mg L−1 GB dose did not positively affect trunk growth (diameter). Kaya (2012) reported that there was a linear relationship between evapotranspiration amounts and trunk diameter in young olive trees [49]. The 1 mg L−1 GB dose did not positively affect fresh root weight under 75% water deficit conditions (I25 treatments). Kayak et al. (2023) reported that the drought stress they applied to spinach caused significant losses in root fresh weight and that the applied GB doses did not contribute [50]. GB doses had no effect on root weight in different irrigation applications in onions [51]. Khadouri et al. (2020) reported that GB applications applied in water deficit conditions were more effective in alfalfa and cowpea [52]. In addition, fresh root weight results obtained from GB applications in water deficit treatments were more than in control (no GB application) treatment. The result is different from this study. The reason for this result may be that using different crops and different water deficit applications. GB5 and GB10 in 50% water deficit conditions had a positive effect on shoot length. Under 40% water deficit conditions, GB application (1.35 g L−1) increased shoot length in the pear trees according to the treatment applied only under 40% water deficit [53]. Jalil (2017) reported that GB doses under water deficit conditions provided higher shoot lengths than plants under water deficit [47]. This effect increased with increasing GB doses. GB dose (0.5%) did not affect the shoot length of young olive trees under different water deficit conditions [29]. The reason for this result can be the late application of GB to olive trees and using only one GB dose. Using a GB dose of up to 10 mM L−1 in tomatoes increased plant vegetative growth [54]. After these dose thresholds, plant growth stopped. Since the highest results were provided from 10 mg L−1 GB applications, a higher dose than 10 mg L−1 GB should be used on pear trees in future studies. Drought stress and GB doses were considered as a different factor and statistical analyses were performed accordingly for all the vegetative parameters (Table 3, Table 4 and Table 5). Drought stress affected trunk diameter, fresh root weight, and shoot length but GB doses had no effect on the vegetative parameters according to the statistical analysis. The reason why GB doses were found to be statistically insignificant in these data was that GB dose was not applied in I100. GB was effective on all the vegetative parameters when it was applied in drought stress conditions. These results show that GB shows its effect under drought stress conditions.

5. Conclusions

All the parameters measured in this study were affected by different GB application doses in both water deficit conditions. Using different GB doses increased vegetative growth, and therefore, ET increased. The 5 mg L−1 and 10 mg L−1 dose applications can be used to obtain this result. The 10 mg L−1 GB dose application positively affected some physiological parameters such as Pn (photosynthetic rate) and gsw (stomatal conductance). The highest results were determined in the 10 mg L−1 GB dose applications in trunk diameter and fresh root weight under 50% water deficit conditions. The shoot length results were in a similar statistical group when 75% water deficit (I25) was applied. When all the results were evaluated together, the most suitable treatment was the 10 mg L−1 (GB10) GB dose. The results show that GB doses should be changed according to the water deficit rate in young pear trees. Glycine betaine should be studied in doses of more than 10 mg L−1 in order to obtain better results for pear trees in future studies.

Author Contributions

Methodology, C.K. and Z.K.; formal analysis, C.K.; investigation, C.K. and Z.K.; resources, S.Ç. and B.İ.; data curation, B.İ. and S.Ç.; writing—original draft preparation, C.K. and Z.K.; writing—review and editing, Z.K.; visualization, C.K. and B.İ.; project administration, C.K. and Z.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Acknowledgments

The authors gratefully acknowledge the help of the research field of Eğirdir Fruit Research Institute, TAGEM (Agricultural Policies and Research General Directorate).

Conflicts of Interest

The authors declare no conflicts of interest.

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Horticulturae 10 01217 g001
Figure 1. The 10-day water consumption of treatments.
Figure 1. The 10-day water consumption of treatments.
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Figure 2. Variation in photosynthetic rate measurements after beginning drought stress applications.
Figure 2. Variation in photosynthetic rate measurements after beginning drought stress applications.
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Figure 3. Stomatal conductance (gsw) measurements after beginning water deficit applications.
Figure 3. Stomatal conductance (gsw) measurements after beginning water deficit applications.
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Figure 4. Transpiration rates (Tr) measurements after beginning water deficit applications.
Figure 4. Transpiration rates (Tr) measurements after beginning water deficit applications.
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Figure 5. Variation in trunk diameter values after beginning water deficit applications.
Figure 5. Variation in trunk diameter values after beginning water deficit applications.
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Figure 6. Shoot development of young pear trees during growing season.
Figure 6. Shoot development of young pear trees during growing season.
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Table 1. ET values and ET decreasing rates of treatments.
Table 1. ET values and ET decreasing rates of treatments.
TreatmentsPlant Water Consumption, ET (L/Plant)Decrease (%)
I100-GB054.20
I50-GB033.837.6
I50-GB135.235.1
I50-GB538.029.9
I50-GB1042.022.5
I25-GB025.153.7
I25-GB126.052.0
I25-GB529.545.6
I25-GB1033.737.8
Table 2. Photosynthetic rate (Pn) and stomatal conductance (gsw) values of the treatments.
Table 2. Photosynthetic rate (Pn) and stomatal conductance (gsw) values of the treatments.
TreatmentsPn
(μmol m−2 s−1)		gsw
(mol m−2 s−1)		Tr
(mmol H2O m−2 s−1)
I100-GB012.83 ± 0.93 a **0.189 ± 0.009 a **5.68 ± 0.04 a **
I50-GB08.45 ± 0.68 cd0.135 ± 0.025 bcde4.00 ± 0.18 c
I50-GB18.53 ± 0.75 cd0.140 ± 0.035 bc4.32 ± 0.39 bc
I50-GB58.95 ± 0.75 c0.154 ± 0.018 b4.51 ± 0.29 bc
I50-GB1010.06 ± 0.82 b0.160 ± 0.009 b4.76 ± 0.22 b
I25-GB07.55 ± 0.78 f0.108 ± 0.008 e3.78 ± 0.16 c
I25-GB17.70 ± 0.74 ef0.110 ± 0.008 de3.80 ± 0.10 c
I25-GB58.20 ± 0.95 de0.120 ± 0.009 cde4.10 ± 0.45 bc
I25-GB109.05 ± 0.98 c0.138 ± 0.009 bcd4.26 ± 0.25 bc
PngswTr
I100 12.82 A **GB0 9.61 nsI100 0.189 A **GB0 0.144 nsI100 5.68 A **GB0 4.49 ns
I50 9.00 BGB1 8.11I50 0.147 BGB1 0.125I50 4.40 BGB1 4.06
I25 8.13 CGB5 8.58I25 0.119 CGB5 0.137I25 3.94 CGB5 4.31
GB10 9.55 GB10 0.149 GB10 4.51
p 0.001p 0.4309p 0.001p 0.6503p 0.001p 0.7277
** p < 0.01, N (number of samples): 9 for each data, ns: nonsignificant. Lowercase letters mean the differences between treatments, uppercase letters mean the differences between applications (irrigation, glycine betaine).
Table 3. Trunk diameter of the treatments (mm).
Table 3. Trunk diameter of the treatments (mm).
TreatmentsTrunk DiameterIncreasing Rates (%)
I100-GB013.87 ± 0.96 a **33.4
I50-GB011.13 ± 0.74 ef10.2
I50-GB111.49 ± 0.82 cde12.7
I50-GB511.76 ± 0.79 bc14.2
I50-GB1011.98 ± 0.96 b17.5
I25-GB010.95 ± 0.80 f7.4
I25-GB111.08 ± 0.94 ef7.6
I25-GB511.28 ± 0.98 def10.6
I25-GB1011.60 ± 0.92 bcd12.6
I10013.86 A **GB011.98 ns
I5011.59 BGB111.29
I2511.23 CGB511.52
GB1011.79
p0.001p0.4876
** p < 0.01, N (number of samples): 9 for each data, ns: nonsignificant. Lowercase letters mean the differences between treatments, uppercase letters mean the differences between applications (irrigation, glycine betaine).
Table 4. Fresh root weight of the treatments (g).
Table 4. Fresh root weight of the treatments (g).
TreatmentsFresh Root Weight
I100-GB043.4 ± 2.98 a **
I50-GB032.0 ± 2.30 bc
I50-GB134.0 ± 3.91 bc
I50-GB534.6 ± 2.05 bc
I50-GB1035.5 ± 2.5 ab
I25-GB027.0 ± 1.28 c
I25-GB127.1 ± 1.67 c
I25-GB530.4 ± 1.51 bc
I25-GB1031.0 ± 1.76 bc
I10043.4 A **GB034.1 ns
I5034.0 BGB130.6
I2528.9 CGB532.5
GB1033.3
p0.0001p0.7749
** p < 0.01, N (number of samples): 9 for each data, ns: nonsignificant. Lowercase letters mean the differences between treatments, uppercase letters mean the differences between applications (irrigation, glycine betaine).
Table 5. Shoot length values of all treatments.
Table 5. Shoot length values of all treatments.
TreatmentsShoot LengthIncreasing Rates (%)
I100-GB031.8 ± 1.48 a *65.8
I50-GB022.3 ± 1.43 b17.3
I50-GB123.3 ± 1.40 b20.9
I50-GB524.4 ± 1.94 ab23.5
I50-GB1025.7 ± 2.25 ab31.0
I25-GB021.0 ± 0.90 b10.5
I25-GB121.8 ± 0.96 b12.4
I25-GB522.4 ± 0.46 b13.1
I25-GB1023.6 ± 0.51 b19.8
I10031.8 A **GB025.0 ns
I5023.9 BGB122.5
I2522.2 BGB523.4
GB1024.6
p0.0015p0.7484
* p < 0.05, ** p < 0.01, N (number of samples): 9 for each data, ns: nonsignificant. Lowercase letters mean the differences between treatments, uppercase letters mean the differences between applications (irrigation, glycine betaine).
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MDPI and ACS Style

Küçükyumuk, C.; Küçükyumuk, Z.; İmrak, B.; Çömlekçioğlu, S. The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions. Horticulturae 2024, 10, 1217. https://doi.org/10.3390/horticulturae10111217

AMA Style

Küçükyumuk C, Küçükyumuk Z, İmrak B, Çömlekçioğlu S. The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions. Horticulturae. 2024; 10(11):1217. https://doi.org/10.3390/horticulturae10111217

Chicago/Turabian Style

Küçükyumuk, Cenk, Zeliha Küçükyumuk, Burhanettin İmrak, and Songül Çömlekçioğlu. 2024. "The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions" Horticulturae 10, no. 11: 1217. https://doi.org/10.3390/horticulturae10111217

APA Style

Küçükyumuk, C., Küçükyumuk, Z., İmrak, B., & Çömlekçioğlu, S. (2024). The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions. Horticulturae, 10(11), 1217. https://doi.org/10.3390/horticulturae10111217

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