Effect of Light Intensity and Temperature on Growth and Quality Parameters of Grafted Vines

Light and temperature are the most important environmental conditions that impact the growth and quality of grafted vines. In this research, the most suitable light and temperature conditions were tested to determine the best environment for grafted vines grown in pots. This study was conducted to determine the influence of different growth conditions, such as open field, shaded greenhouse and unshaded greenhouse, on grafted vine growth and quality. The length and diameter of shoot, trunk diameter, mean and total leaf area, total soluble sugars, starch and total carbohydrate contents of ‘Narince’ and ‘Trakya Ilkeren’ vines, grafted on 5C rootstock, were investigated in this study. Shaded conditions yielded significantly higher shoot lengths, mean and total leaf areas than other conditions (p<0.05). Among the growth parameters, the highest correlation (r = 0.819) was observed between shoot length and plant total leaf area (p<0.01). The total soluble sugars, starch and total carbohydrates content of vines under shaded and unshaded conditions were higher (p<0.05) than those under open field conditions. Grafted vines had the highest carbohydrate content in unshaded conditions. Under different light intensity, temperature and relative humidity conditions studied, the better results were obtained in the case of unshaded conditions.


Introduction
Grafting Vitis vinifera varieties onto resistant rootstocks represents the most effective way of protecting crops against phylloxera (Vršič et al., 2004).Especially in phylloxeracontaminated areas, where the establishment of suitable vines on their own roots is virtually impossible.The only successful means of controlling phylloxera has been the grafting of phylloxera resistant rootstock (Troncoso et al., 1999).Because of this, grafted vines should be be used during the establishment of new vineyards regardless of the phylloxera infection.Quality grafted vines allow for the successful growth and development of both root and vegetative organs after planted in a vineyard.Healthy vineyards are only possible with healthy and quality grafted vines.Nursery soil characteristics and climate conditions have significant impacts on the success of grafted vine operations especially during the initial 2-3 weeks after planting grafted cuttings (Çelik et al., 1992).For successful production, control of the nursery's climatic conditions should be taken.A temperature of 25 °C and 85-95% relative humidity should be provided within the growing conditions for good callus formation (Karakır et al., 1988).Several other environmental factors also affect the growth and development of the plants (Arnold and Mauseth;1999;Buttrose, 1969;Bindi et al., 1997;Oztürk and Serdar, 2011).The most important of these factors are light, temperature, water (humidity) and nutrition.Light and temperature are two important parameters that affect the physiology of the grapevine.Plants are need light and temperature for basic physiological processes such as photosynthesis, respiration transpiration and carbohydrate assimilation (Agaoglu et al., 1995;Uzun and Demir, 1996).Sivritepe and Türkben (2001) was obtained rooting grafted cuttings between 30.47% and 73.75% on five different rootstocks belonging to the 'Müşküle' grape variety at 25±2°C temperature, 70-75% humidity and 16 hours photoperiod.Yılma (1996) stated that 5BB grafting cuttings of 'Abalıkoca' and 'Kazova' grapes grown under white transparent polythene plastic mini tunnel systems gave the highest rooting rate.Light is another crucial environmental factor determining the morphology and physiology of leaves (Neri et al., 2003).It plays a significant role in physiological processes in plants such as photosynthesis and transpiration (Fluhr et al., 1986;Wang et al., 2014).Sultanina grapes growing under greenhouse conditions required light intensity and temperature at respective rates of 60.000 lux and 25°C for optimum assimilation rates (Kriedemann, 1968).Kısmalı (1984) reported certain increases in photosynthesis capacities with increasing light intensities of greenhouses but also noted that photosynthesis reached full capacity at a certain point even with increasing light intensities.
Carbohydrates, which are stored in plants' roots, trunks, cordons and canes, play major roles in the growth and were measured with a data logger and resultant values are provided in Figs. 1 and 2 for both experimental years.Light intensity (PAR) was measured in 15-day periods between the months of June and September of both years with a canopy analyzer device and expressed in µmolm -2 s -1 (Tab. 1 and Fig. 3).In the study, some growth parameters such as total and mean leaf area, shoot length, trunk and shoot diameter were measured in August.Mean leaf area was determined by dividing the total leaf area of the shoot with the number of leaves over the main shoot.Leaf areas were calculated nondestructively [-1.41 + 0.527(W 2 ) + 0.254(L 2 )] according to Elsner and Jubb (1988).All measurements were repeated in the second year on annual cuttings.development of plants.During the bud burst period, carbohydrates are moved from the roots and woody organs to the growing shoot, providing new leaves and other organs with essential reserves needed for growth.Young shoots and leaves utilize carbohydrates for growth and metabolism until they reach approximately a third of their final size (Hale and Weaver, 1962).Buttrose (1968) stated that dry weights of roots, canes, stems, and leaves increased with increasing light intensity and were greater at 25 °C than at 20 °C or 30 °C.Richards (1976) reported that grafted vines produced very good growth results in an environment of around 25 °C.Researchers suggested the optimum temperature for the photosynthesis of grapevines as between 25 °C and 35 °C (Greer and Weedon, 2012;Kriedemann, 1968;Mullins et al., 1992;Schultz, 2000).However, temperatures above 35 °C, generally reduced the photosynthesis rates of grape leaves (Ferrini et al., 1995;Kriedemann, 1968;Luo et al., 2011;Yu et al., 2009;Zsófi et al., 2009).The lowest net photosynthesis values were recorded in vines grown at 35 °C and were closely correlated to chlorophyll content.The effect of this temperature on stomatal conductance was less remarkable and the dry matter accumulation was correlated to average photosynthesis rates (Ferrini et al., 1995).
From dig out till grafting, various factors effect vine growth and quality.The quality of grafted vines diminishes after planting vineyards.Having the best quality vines is a crucial factor for successful grapevine growing.The aim of this study was to determine the influence of different growth conditions (open field, shaded greenhouse and unshaded greenhouse) on the growth and carbohydrate content of grafted vines.

Materials and methods
Experiments were conducted in the experimental fields and plastic greenhouses of Ondokuz Mayis University's Agricultural Faculty.'Narince' and 'Trakya Ilkeren' scions (Vitis vinifera L. cvs.) were grafted on 5C rootstock.'Narince' is the most important white wine grape in Turkey and is used both as a table food and for wine in the country.'Trakya Ilkeren' ('Alphonse Lavallée' x 'Perlette') is a very early maturing red table grape.In addition, this grape is quite suitable as a wrapping leaf for foods and for greenhouse cultivation.Material supply, grafting and callusing processes were performed at Tekirdağ Viticultural Research Station.The scions and rootstocks were stored at +2 °C until two months until grafting.The omega grafting was done at the beginning of April and grafted cuttings were stored for 3 weeks at 28 °C and one week at 26 °C in a callusing room.Callused cuttings were planted in 10-L plastic pots with a soil, sand and manure (1:1:1) potting mix (substrate content not analyzed).Plants were irrigated everyday with 1.5 L of water in the early morning.In order to provide different light and temperature conditions, vines were grown in shaded and unshaded greenhouse and open field conditions.Similarly, to render equal soil conditions, the vines were grown in pots.The pots were placed under different growth conditions at the beginning of May.Among the rooted ones, uniformly growing vines were selected for the calculation of certain growth parameters.Shading was provided through netting with a light transmission of 50%.The temperature and relative humidity

Carbohydrate analysis
During the dormant periods of the plants, a 2 cm piece between the 2 nd and 3 rd nodes from the bottom of the canes; a 2 cm piece from the mid-section of the stem; a piece between 2.5-4 mm from the older sections of the roots; and a 1-2 mm piece from the younger sections of the roots were cut out and grinded together (Bates et al., 2002).Plant tissue samples were pulverized in a mill with a 40-mesh screen for analysis and 200 mg of dust was used for the extraction.Soluble sugars were extracted twice with 8 ml of 80% ethanol at 60 °C for 30 minutes (Candolfi and Koblet, 1990).The content of soluble sugars was determined with the anthrone method as described by Scott and Melvin (1953).Starch was extracted twice with 8 ml of 1 M perchloric acid, one hour each time at 60 °C and measured by the same method.Absorbance readings were made at 620 nm with a spectrophotometer.Glucose was used as a standard for the analysis of soluble sugars and starch.

Experimental design
The randomized complete block design, with three replications, was used both years.Every replication consisted of four uniformly grown grafted vines.Growing conditions, cultivars, years and these interactions were studied by threefactored ANOVA.Data analysis was performed using SPSS 16.0 for Windows.Results studied are presented as means and a pooled standard error of mean (SEM).Differences among means were detected using Duncan's multiple range tests, which were used for statistical analyses (p≤0.05).Correlation analysis was applied to assess the relationship between growth parameters and sugar, starch and total carbohydrates.

Results and discussion
Changes in temperature, humidity and light intensity Data related to average temperature (°C), relative humidity (%) and light intensity (µmolm -2 s -1 ) determined daily after the planting of grafted cuttings during the research are shown in Tab. 1 and Fig. 1, 2 and 3. Average temperature, relative humidity and light intensity values under different growth conditions throughout the growth seasons of experimental years are provided in Tab. 1.
Under unshaded, shaded and open field conditions, average temperatures were respectively calculated as 24.9 °C, 22.1 °C and 18.8 °C.Under the same conditions, average light intensities were respectively calculated as 1315.4,662.2 and 1846.1 µmol m -2 s -1 .

Vine growth and development
Shoot lengths and diameters, trunk diameters, total and mean leaf areas of grape cultivars grafted on 5C rootstocks under different conditions (shaded and unshaded greenhouses and open field) for both years are presented in Tab. 2. Shoot lengths were significantly affected by growth conditions, year and growth conditions x year interaction (p<0.05).The shoot lengths were higher under shaded conditions than in other growth conditions.In the study, decreasing light intensities and increasing temperatures conditions affected shoot lengths.Low light intensities and high temperatures (shaded and unshaded) lead to the elongation of plant heights (Fig. 4).Mean shoot length was 201.6 cm under shaded greenhouse conditions, 117.2 cm under unshaded greenhouse conditions and 62.3 cm under open field conditions (Tab.3).
Year also significantly affected growth characteristics (Tab.2).Strong shoot and leaf development of the first year also resulted in larger shoot diameter the same year.Similarly, trunk diameter of vines in the first year was also larger than in the second year.This was due to weak growth in the second year.Although similar environmental conditions and cultural practices were applied, all growth parameters in the first year were higher than in the second year.These differences might have been from a difference in the organic composition of the soil mix and relative humidity.There was no effect of cultivars on growth.The cultivars were only significant on leaf areas.Larger leaf areas of growing vines were obtained under shaded conditions.Despite the fact that shoot and trunk diameters were not affected by growing conditions (Tab.2, 3), there was a trend for the shoot and trunk diameters under the shaded greenhouse conditions in both years to be higher (8.4 mm and 13.6 mm, respectively) (Tab.3).510 (Baldocchi and Amthor, 2001;Koblet, 1984;Matloobi, 2012).Field et al. (2009) reported that the shoot and trunk dry biomass of potted Shiraz grapevines grown at 23 °C in a glasshouse were significantly greater than those grown at 13 °C.Skelton (2007) reported that the soil surface requires a cover of black polythene to keep in moisture and raise the soil temperature to aid in vine development, a strong graft union and a good root system.Tab. 3. Mean shoot length (cm) and diameter (mm), trunk diameter (mm) and leaf area (cm 2 ) values of grafted vines under different conditions Shoots lengths, mean and total leaf areas per plant were affected by the growth conditions (Tab.2).Light intensity measured under shaded conditions was about one-third of that in open field conditions (Tab.1).Shoot length increased with decreasing light intensity.Leaves growing at different light levels differ in their anatomy and physiology.While increasing light intensities yield improved photosynthesis rates of vine leaves, decreasing light intensities cause longer internode spacing, weak growth, embrittelement and larger leaf areas.Aside from this, such decreasing lighting intensities also result in decreased photosynthesis rates, etiolating and defoliation (Eris, 1990).The results of the study indicated that different light and temperature conditions had significant effects on shoot growth, total leaf area and mean leaf area, especially in the shaded conditions.According to TS 3981 (Anonymous, 1995), first class vines have to have at least 20 cm of shoot length and a trunk diameter of 7 mm.In the study, the average shoot length was above 60 cm, shoot diameter was 7.9 mm and trunk diameter was 12.9 mm.All growth combinations of the first class of grafted vines were according to growth parameters studied in the research (Fig. 4).
Temperature is the most important environmental factor for canopy development and leaf photosynthesis

Leaf growth and development
The total and mean leaf areas of grape cultivars grown under different conditions (shaded and unshaded greenhouses and open field conditions) with respect to years and cultivars are presented in Tab. 2. Growth conditions significantly affected the leaf areas of different varieties.Tab. 2 shows that the grape cultivar has a significant effect upon mean and total leaf area and there were significant effects of the year and nursery conditions on leaf area.The mean and total leaf areas of grapes which were grown under shaded greenhouse conditions were significantly higher than those grown under unshaded greenhouse and open field conditions in both years (Tab.3).On the other hand, growth conditions x cultivar x year interaction had a significant effect on total leaf area but not on mean leaf area.Significant differences were observed in leaf areas of cultivars (Fig. 5).The average total leaf area of vines was calculated as 5229 cm 2 in the first year and as 2869.3cm 2 in the second year.Similarly, mean leaf areas of the first and second years were respectively observed as 74.3 and 63.3 cm 2 (Tab.2).The highest total leaf area was at shaded 'Trakya Ilkeren' (6154 cm 2 ) whereas the lowest at open field 'Narince' cultivar (2643 cm 2 ).However, the highest mean leaf area was at shaded 'Narince' (107.2 cm 2 ), whereas the least mean leaf area was at unshaded 'Trakya Ilkeren' (40.8 cm 2 ) cultivar.Reducing light intensity led to the increased leaf area of cultivars.Bonan (2002) was impressed that leaves growing in sunny environments were smaller and more deeply lobed than leaves growing in shaded environments.Furthermore, the leaf area ratio was 2.7 times greater and leaf weight ratio was about 20% greater in shaded plants compared with sun plants.The reported acclimation to low light was not restricted to dry-weight allocation among shoot organs because the specific leaf area Data showing significant effects was obtained concerning interactions such as growth conditions x cultivar, cultivar x year and growth conditions x cultivars x year (p<0.05).While significant differences were observed in sugar and starch contents of the years, effects of years on carbohydrate contents were not significant (Tab.4).While the first year's sugar content was high and starch was low, the second year's sugar content was low and starch was high.So in both years, total carbohydrate content was not significant.
In the study, the total soluble sugars, starch and total carbohydrate content of the vines grown under unshaded greenhouse conditions were higher than that of the other conditions (Fig. 6).Effects of cultivars x conditions on starch and carbohydrate content were significant except for sugar only in the open field condition (Tab.4).In spite of that, the mean sugar content of grafted vines grown under shaded greenhouse conditions (14.6 mg L -1 ) and unshaded greenhouse conditions (14.3 mg L -1 ) were found to be a bit higher than the ones grown under open field conditions (12.4 mg L -1 ) (Tab. 5).
Carbohydrate contents of grapevines in this study were significantly affected by growth conditions.Starch and carbohydrate contents of plants grown under unshaded greenhouse conditions were higher than the plants grown under shaded greenhouse and open field conditions (Tab.5, Fig. 6).Growth conditions x year, cultivar x year and growth conditions x cultivar x year interactions were found to be significant with regard to sugar, starch and carbohydrate content.Mean sugar content was 15.8 mg L -1 in the first year and 11.8 mg L -1 in the second year; starch content was 38.5 mg L in the first year and 43.4 mg L -1 in the second year; carbohydrate content was 54.3 mg L -1 in the first year and 55.2 mg L -1 in the second year (Tab.4).In brief, the sugar, starch and carbohydrate content of plants grown under high light intensity (1846.1 µmolm -2 s -1 ) and low temperature (18.8 °C) conditions (open field) were lower than the ones grown under lower light but higher temperature conditions (662.2 µmolm -2 s -1 , 22.1 °C for shaded greenhouses and 1315.4 µmolm -2 s -1 , 24.9 °C for unshaded greenhouses).However, the highest sugar, starch and carbohydrate content was obtained around 25 °C and 30% lower light intensity (unshaded) in all the conditions (Fig. 6).Such a case seemed to be related to decreased photosynthesis efficiencies under high light but low temperature conditions.Among growth conditions, average relative humidity varied.The highest relative humidity (66%) was observed under shaded greenhouse conditions and the lowest (45.4%) under open field conditions (Tab.1).Relative humidity of the first year was higher than that of the second year under all growth conditions.According to Jang et al. (2011) generally, 75-85% relative humidity levels accelerate the photosynthesis rate.In grapevines, carbohydrates in roots and wood portions play important roles for vine longevity and quality.Indeed, carbohydrates are not only involved in the protection against frost (Keller, 2010), but they also take part in leaf area development, shoot growth and flower induction (Keller and Koblet, 1994;Murisier and Aerny, 1994;Yang and Hori, 1979).Carbohydrate accumulation correlated with photosynthesis efficiency in the plants.In addition, photosynthesis is highly dependent on temperature, light intensity and relative was increased to about 100% by the low-light environment.Increased shading resulted in increased leaf areas and wider leaves.Gutschick and Wiegel (1988) stated that deeper shade allowed plants to construct a greater leaf surface area for light interception at a certain biomass investment in foliage.Excess sun energy may have harmful effects on the photosynthetic devices, and plants arrange morphological, biochemical and physiological strategies to minimize these effects (Lichtenthaler and Burkart, 1999;Lichtenthaler et al., 2007).Leaf area plays a key role in determining crop productivity by controlling the interception of solar radiation (Monteith, 1977).In grapevines, the rate of photosynthesis production of fully expanded leaves depends on air temperature (Buttrose, 1969).In addition, there is a direct connection between intercepted solar radiation and plant leaf area to shoot development and accumulated assimilates in plant organs.For example, Cartechini and Palliotti (1995) reported that grapevines acclimate to modified light intensity and produce a given amount of carbohydrates.Shade-grown vines (30% PPF) had lower total leaf area and soluble carbohydrates per plant and lower starch content in leaves compared to light adapted grapevines.Buttrose (1968) reported that cuttings of grapevines stem lengths and leaf area values grown in growth cabinets were in most cases greatest at 25 °C followed in turn by 30 °C and 20 °C values.Miller et al. (1996) indicated a linear relationship between leaf area and shoot lengths of vines.In the research, a relationship was observed between leaf area and shoot length.Shoot length, total and mean leaf areas of the grafted vines grown under shaded greenhouse conditions were higher than that grown under other conditions.There was a highest correlation observed between shoot length, total and mean leaf area (Tab.6).Total leaf area was correlated between trunk diameter (r=0.577,p<0.01), shoot diameter (r=0.646,p<0.01) and shoot length (r=0.819,p<0.01) per plant.humidity (Gomes-Laranjo et al., 2006;Koorneef et al., 2002).It was reported that the optimal temperature range for photosynthesis was between 26-30 °C, with a decrease of about 50% when the temperature increases to 32-34 °C; the decrease being higher than 80% when temperatures reach 38 °C in chestnut (Gomes-Laranjo et al., 2006).Schultz and Matthews (1993) stated that in potted-grown White Riesling grapes dry-weight allocation of leaves of shaded plants was 9% greater, whereas allocation to stem tissue was 10% less than in sun plants.Photosynthesis rates decrease at temperatures above the optimum levels (Spayd, 2000).In the case of temperatures up to 40 °C, the photosynthesis of grapevine leaves are significantly reduced (Ferrini et al., 1995;Kriedemann, 1968;Yu et al., 2009;Zsofi et al., 2009).Greer and Weedon (2012) reported remarkable decreases in the photosynthesis of Semillon grape leaves at temperatures above 35 °C.In part, these reductions in photosynthesis are related to stomatal limitation due to high temperature (Ferrini et al., 1995;Sepúlveda and Kliewer, 1986;Soar et al., 2009).
Most of the physiological processes of plants are related to carbohydrates.Carbohydrates are the most important products of photosynthesis and they are the most significant component of various physiological processes.In general, carbohydrates constitute about 50-80% of the total dry weight of most plants (Eris, 1990).Goldschmidth (1997) indicated the role of carbohydrates in various physiological processes of plants as the source of energy.Monteith (1977) reported linear relationships between dry matter accumulation and total PAR (Photosynthetic Active Radiation) up to a certain point.However, since high light intensities may damage plant chlorophylls, photosynthetic efficiencies of plants may decrease because of photoinhibition.Bertamini and Nedunchezhian (2004) reported net photosynthesis under low and high light intensities respectively as 42 and 76% lower than the normal light conditions.Thus, photosynthesis rates increase at optimum temperature levels.Since the average temperatures in shaded and unshaded greenhouses were within the optimum range of temperature (25-30 °C) for photosynthesis, the plants had higher carbohydrate contents under shaded and unshaded greenhouse conditions than those under open field conditions.Higher total and mean leaf areas of the plants under shaded and unshaded greenhouse conditions also resulted in higher carbohydrate contents for those plants than the ones grown under open field conditions (high light, low average temperature).Accordingly, there was also a significant correlation between total leaf area and sugar content (Tab.6; r=0.695, p<0.01).

Conclusions
According to the results of this study, vines' growth and quality characteristics were affected by different growth conditions.The vines grown under unshaded and shaded conditions exhibited higher performances than the ones grown under open field conditions.Shoot lengths and leaf areas were especially affected by decreasing light intensities and increasing temperatures.Additionally, the carbohydrate content of vines was affected by growth conditions.Higher carbohydrate levels were observed under increasing temperature and decreasing light intensity conditions as opposed to higher light intensity and lower temperature conditions.However, all three growth conditions produced top quality vines.Providing optimum temperature or the establishment of nurseries obtaining these temperature regions is gaining importance in the area of quality grapevine production.To reduce the negative impact of high light intensity on plants, canopy shading throughout the growth cycle should be provided.In this study, better growth and quality results were obtained under high temperatures (25 °C) and low light intensity conditions (1300 µmol m -2 s -1 ).Tab. 6. Correlations amongst the plant growth parameters and carbohydrates

Fig. 3 .
Fig. 3. Course of light intensity throughout the experimental years Aug. Sept. Oct. Nov. May June July Aug. Sept. Oct. Nov.First YearSecond Year

Fig. 4 .
Fig. 4. Shoot lengths of grape cultivars grown in shaded and unshaded greenhouses and in the open field conditions in two different years; means with different letters in the same column were significantly different at P < 0.05

Fig. 5 .
Fig. 5.Total and mean leaf areas of grape cultivars grown in shaded and unshaded greenhouses and in the open field conditions in two different years; means with different letters were significantly different at P<0.05Plant carbohydrate contentsThe total soluble sugars, starch and total carbohydrate contents of different grafted vine cultivars under different growth conditions (shaded and unshaded greenhouses and open field) are presented in Tab. 4. Growth conditions had significant impacts on sugar, starch and carbohydrate contents of grafted vines (Tab.5).

Tab. 4 .
The sugar, starch and total carbohydrate content (mg L -1 ) of grafted vines grown under shaded and unshaded greenhouses and open field conditions Tab. 5. Mean sugar, starch and carbohydrate contents (mg L -1 ) of grafted vines grown under shaded and unshaded greenhouses and open field conditions

Fig. 6 .
Fig. 6.Sugar, starch and total carbohydrate content of grape cultivars grown in shaded and unshaded greenhouses and in the open field conditions in two different years; means with different letters were significantly different at P<0.05 Tab. 1. Temperature, relative humidity and light intensity values under different nursery conditions throughout the growth seasons of experimental years Tab. 2. Shoot lengths (cm) and diameters (mm), trunk diameters (mm), total and mean leaf areas (cm 2 ) of different grafted vine cultivars under different conditions *Pooled SEM: Pooled standard error of the mean (NS.p>0.05; *. p<0.05).
Means represent the averages for cultivars and years).
Means with different letters in the same column were significantly different (*p<0.05).