Determination of the Optimum Mulch-Irrigation Program Combination for Young Apple Trees

Su kaynaklari icin talep giderek artmaktadir ve tarimsal uretimde sulama suyu tasarrufu saglayan ve verim, urun kalitesi, buyume ve gelisme uzerinde olumsuz etkileri olmayan yetistirme tekniklerine olan ilgi de artmaktadir. Bu calisma, MM106 anacli Fuji elma cesidinde farkli malc uygulamalari (siyah taban ortusu, gul posasi isleme atigi, bugday samani ve malcsiz konu-kontrol) ve sulama programlarinin sulama suyu, evapotranspirasyon, surgun capi, surgun sayisi, surgun uzunlugu, yaprak alan indeksi ve govde kesit alani uzerinde etkilerinin belirlenmesi amaciyla yapilmistir. Her bir malc uygulamasi icin uc farkli sulama programi (sulamaya etkili kok derinligi bolgesindeki elverisli suyun %20, 40 ve 60’i tuketildiginde baslama) en uygun sulama programini belirlemek icin denenmistir. En yuksek vejetatif gelisim malc uygulamalarinda ve sik sulama yapilan 1. sulama programlarinda elde edilmistir. Tavsiye edilen sulama programi su kaynaklarinin elverisli ve yeterli oldugu bolgelerde 1. sulama programidir. Elverisli su kaynaklari miktarinin yetersiz oldugu zamanlarda ise malc uygulamalariyla birlikte 2. sulama programi da uygulanabilir. Malc uygulamalarindan elde edilen su tasarrufu miktari control konusuna gore 2009, 2010 ve 2011 yillarinda sirasiyla 22.0-31.3%, 21.2-28.7% and 17.8-23.5% arasinda degismistir. Su tasarrufu ve vejetatif gelisim sonuclarina gore genc elma agaclari icin siyah taban ortusu en uygun malc materyali olarak belirlenmistir. Gul posasi isleme atiklari ve bugday samani da malc materyali olarak kullanilabilir.


Introduction
As the using of water in other fields (industrial production, domestic use, etc.) has been increasing over the time, the available water amounts for agricultural production have been decreasing (Önder et. al., 2005). So to increase water-use efficiency is mandatory (Naor et. al., 2008). That's why, available water resources must be used more carefully. The importance of studies for more efficient use of available water resources is increasing. The studies on the applications which ensure water saving and do not have the negative effects on vegetative development, yield and crop quality are going on all over the world. Mulch using is one of these applications. It provides water saving and has positive effect on plant growth development besides preventing weed growth in apple orchards (Neilsen, et al., 2003;Hogue et. al., 2005).
Amount of irrigation water and irrigation time of plants must be determined accurately to get full efficiency from irrigation (Barragan and Wu, 2001). Haphazard irrigations obstruct plants from obtaining irrigation efficiency which results in un-desired consequences such as salinity-sodium, high cost and low yields. Apple production quantity of Turkey is estimated as 4.0 % of the world's total apple production and apples are one of the most important fruits produced (FAO, 2019). Isparta is at first rank on apple production nearly 20.4% of the country's total (3.618.752 tons) (TUİK, 2019). There are some problems on apple growing (irrigation scheduling, weed control etc.) (Küçükyumuk and Ay, 2010).
This study was aimed to determine the effects of different mulch materials namely black textile, straw (wheat straw) and rose oil processing wastes on water saving, evapotranspiration and vegetative development of Fuji apple variety (grafted onto MM106 rootstock. Also, three different irrigation programs have been used for each different mulch materials and the most suitable irrigation program was determined for Fuji variety grafted on MM106 rootstock.

Study area and plant material
This experiment was conducted for the three consecutive years (2009-2011) at Fruit Research Institute (37°49'17.97"N and30°52'22.44"E), Eğirdir-Isparta, Turkey. The experimental area has a transition climate between Mediterranean and Central Anatolia. The soil of experimental area was loamy, contained low salt content, pH 8.15 and low soil organic matter content. Table 1 shows the physical properties of the experimental soil. According to US Salinity Laboratory Graphical System, the salinity level of the irrigation water, which are in 250-750 ECx10 6 is included in category C2, and S1 in terms of SAR value (USSL, 1954). Irrigation water was classified as C2S1 suitable for irrigation of the experimental plots. Apple trees were planted in March 2009 at 4 m x 3 m of distance and Fuji variety (grafted onto MM106 rootstock) was used in this experiment.

Study treatments
The study was conducted considering consisted of four mulch treatments (including control) and three different irrigation programs for each mulch treatments. Mulch treatments: no mulch, Control (C); black textile-polypropylene woven cloth (100 g m -2 ) (B); straw-wheat straw (S) and rose oil processing wastes (R)-the rose waste obtained from the wastes of the rose oil processing factories in Isparta province of Turkey were used after sun-dried. Each mulch treatment had three different irrigation programs (1 st , 2 nd and 3 rd irrigation programs) 1 st , 2 nd and 3 rd irrigation programs treatments include irrigation of the field with water holding capacity of 20, 40 and 60% was used at 0-90 cm depth of the soil.
In the study, drip irrigation system was used. Two lateral pipes were used for each tree row. The emitters (having 4 l h -1 flow rate) spacing were 0.75 m on each lateral sides. Digital tensiometers (Soilspec digital tensiometer, JGK TECH, Australia) were used for measuring soil water (placed at 30, 60, 90 and 120 cm depth). Before first irrigation, calibration of tensiometers was made to determine the soil water which corresponds. Programmed irrigation applications were initiated after the available moisture at 0-90 cm soil depth was reached to field capacity at the end of the full bloom period each year.

ET = I + R + Cr -Dp -Rf ± Δs
(1) In Equation (1); ET, evapotranspiration (mm); I, irrigation water amounts (mm); Cr, capillary rise (mm); R, rainfall (mm); Rf, surface run-off (mm); Dp, water leakage by deep percolation (mm); Δs, change in profile soil water content (mm). Cr and Rf were considered as zero, since there were not any ground water problems in the area and emitter discharge rate was selected in accordance with infiltration rate. Deep percolation was calculated after each precipitation during irrigation season. Precipitation was measured with a pluviometer after every rainy day. For determining the irrigation water amounts, The Equation (2) was used (Kanber, 2002).
The plots were irrigated until they reached field capacity for each irrigation. After the nurseries were planted in March 2009, weeds in the study area were hoed on 15 May, and drip irrigation system was laid. After placing tensiometers, mulch materials were laid on both sides of the trees with 0.70 m width, and in total 1.40 m width. The thickness of straw and rose oil processing wastes was 0.20 m.

Measurement of vegetative growth
Beginning from the planting year, shoot numbers, shoot diameter (mm) and shoot length (cm) of single-year shoots for all trees were measured in during dormancy period in February. Digital calipper was used for measuring shoot diameter.

Leaf area index (m 2 /m 2 )
Totally 250 leaves were picked from the one year old shoots of all trees for each plot to determine leaf area index at the end of September during study. The digital planimeter (Koizumi KP-90 N) was used to measure leaf area. We calculated "leaf area index" by using Equation 3 (Ünlü, 2000).

Total leaf area (for each tree) = Leaf area (m 2 ) x total leaf numbers (for each tree)
Leaf area index (m 2 /m 2 ) = Total leaf area (m 2 ) (for each tree) Unit area for each tree (m 2 ) (4 m x 3 m) (3)

Trunk cross-section area (cm 2 )
In the first year, after the planting and in the following years, every year during dormancy period, the trunk diameters of all trees were measured on two different directions (east-west and north-south) at 15 cm above the graft point of all trees, and trunk cross-sectional areas were calculated by means of the Equation (4).

Experimental design and statistical analysis
The experiment was designed according to split plot design. Main plots were mulch treatments and sub plots were irrigation programs. There were three replications for each treatments and each replication had twenty one apple trees ( Figure 1). Only five trees (grey color in Figure 1) were used for measurements. The analysis of variance (ANOVA) test for the data was conducted with JUMP software program and differences among treatments were compared by means of LSD test. Figure 1. An experimental plot of the study.

Irrigation water (I) and evapotranspiration (ET)
Irrigation water (I) and evapotranspiration (ET) were presented in Table 2, Table 3 and Table 4.

Shoot number
Shoot numbers obtained during the study is shown on Table 5. It was determined that mulch and irrigation program treatments had statistically important effects in 2009 (p<0.01). The highest vegetative development was obtained from black textile and rose oil processing wastes mulch treatments and from 1 st irrigation program among irrigation programs. Mulch x irrigation program interaction was found significant in 2010 (p<0.01). The highest shoot numbers were determined in 1 st and 2 nd irrigation programs of the mulch treatments. According to the results in 2011, the mulch and irrigation programs had separate effects on shoot numbers (p<0.01). Black textile and the 1 st irrigation program had the highest values among treatments. In general, mulch treatments had a positive effect on shoot numbers and it was observed that 1 st irrigation program also had a similar effect.

Shoot length
According to the results of shoot length (Table 6), the mulch x irrigation program interaction in 2009 and 2010 was effective as statistically 1% level (p<0.01). 1 st and 2 nd irrigation programs in mulch treatments had the highest values. Mulch and irrigation program had separate effects (p<0.01) in 2011. The highest shoot lengths were obtained from black textile among mulch treatments and from 1 st irrigation program among the irrigation programs.

Shoot diameter
According to the results of shoot diameter (Table 7), mulch x irrigation program interaction in 2010 was found significant while mulches and irrigation programs had separate effects in the other years. The highest shoot diameter values in 2009 were obtained from rose oil processing wastes and black textile in mulch treatments and from 1 st irrigation program. 1 st and 2 nd irrigation programs of mulch treatments had the highest shoot diameter according to the results of 2010. In the last year, black textile was at the first rank among mulch treatments, and 1 st and 2 nd irrigation programs were in the same group statistically.

Leaf area index (LAI)
While mulch x irrigation program interaction had significant effect on LAI (p<0.01) in 2010, mulch and irrigation program had significant effects on LAI (p<0.01) separately in 2011. LAI values ranged between 0.123 m 2 m -2 and 0.238 m 2 m -2 in 2010. Black textile x 1 st irrigation program interaction had the highest LAI and the lowest LAI was obtained from control x 3 rd irrigation program interaction. LAI was ranged 0.136 m 2 m -2 and 0.333 m 2 m -2 and black textile mulch had the highest average LAI (0.258 m 2 m -2 ) in 2011. Straw and rose oil processing wastes had similar results. LAI values of study in 2011 were higher than LAI values in 2010. According to irrigation programs, while irrigation water amounts increased, LAI increased.

Trunk cross-sectional area (TCSA)
At measurements after planting in 2009, there was no differences among all treatments as statistically (Table 9). According to the measurements results of 2009 following the first measurement, mulch treatments and irrigation programs have separate effects (p<0.01). The highest values were obtained from black textile among mulch treatments and from the 1 st irrigation program among the irrigation programs. The effects of mulch x irrigation program interaction were significant in 2010 and 2011 (p<0.05). A significant increasing was determined of measurements TSCA for all treatments during the study.

Irrigation water (I) and evapotranspiration (ET)
As the mulch materials prevented the sunlight, the evaporation from the soil surface was minimized; therefore, evapotranspiration decreased and also irrigation water amounts. Rose oil processing wastes mulch was less effective than wheat straw mulch, while black textile mulch was the most effective. For example, in 2009, applied irrigation water amounts was 424.1 mm to the control treatment for the 1 st irrigation program while it was 330.6 mm, 306.4 mm and 291.0 mm in rose oil processing wastes, straw and black textile mulch treatments, respectively. Irrigation water amounts obtained from mulch treatments were in the range of 306.7-363.7 mm and 363.1-414.9 mm for second and third years old apple trees. Uçar et al. (2009) obtained for Galaxy Gala apple variety grafted onto M9 rootstock without mulches as between 355.7-446.5 mm and 359.2-538.9 mm for two and three years old apple trees in the same area. When comparing the results, it can be said that mulch treatments had water saving.
Mulch treatments had significant effects on irrigation intervals. Whilemore frequent irrigation was made in control treatment, irrigation interval was longer for mulch treatments. Irrigation numbers and amounts were the highest for the 1 st irrigation treatments. For example, while irrigation interval for 1 st irrigation programs were 4 days for control treatments, they were 5-6 days for the other treatments.
Some of researchers stated that more soil water could be stored at root zone with mulching and irrigation interval was longer than no mulch treatments and less amounts of irrigation water was used (Treder et al., 2004;Hogue et al., 2005;Zambreno et al.;Li et al., 2013).
Irrigation water and plant water consumption increased for all treatments continuously during the study. Reason for the increasing is that young apple trees growth continuously from year to year. Similarly, the differences among irrigation water amounts of control and mulch treatments was higher in 2009 while it narrowed down in 2010 and 2011. The reason is, apple trees in mulch treatments had higher vegetative growth compared to trees in control treatments, therefore they consumed more irrigation water. Water saving in mulch treatments was %22. 0-31.3, %21.2-28.7 and %17.8-23.5 in 2009, 2010 and 2011, respectively, when it was compared to control treatment. Phadung et al. (2005); Hegazi and Oguer (2000); Treder et al. (2004) and Hogue et al. (2005) obtained similar results.

Vegetative growth
The highest shoot development was determined in 1 st irrigation program with frequent irrigation and lower values were obtained from 3 rd irrigation program with less irrigation water amounts. That is, the vegetative development was effected negatively as irrigation interval increased. Frequent irrigation of apple trees had positive effects on the vegetative development (Çay et al., 2009;Uçar et al., 2009), less water or water stress had negative effects on the vegetative development of apple trees (Lakso, 2003;Naor, 2006).
According to the results of shoot numbers, shoot length and shoot diameter in 2011, it was determined that the rose oil processing wastes, wheat straw and control treatments were generally in same group as statistically. Because the thicknesses of the wheat straw and rose oil processing wastes decreased in time, their effectiveness also decreased. This is why they had similar results. As synthetic mulch materials are more effective on the water preservation compared to organic mulches (wheat straw, rose oil processing wastes etc.), black textile was more effective on the vegetative development of the trees.

Leaf area index (LAI)
Leaf area measurements is important as for monitoring the plant development (Kılıç and Anaç, 2005) as the leaves are a very important stress indicator for plants (Kocaçalışkan, 2005). Therefore, leaf area index is also important indicator for plants. The highest leaf area index were was obtained from mulch treatments and 1 st irrigation program. The treatments with a greater leaf area index may be recommended as it is also a good indicator of plant development. Young apple trees growth continuously. So they had more leaf and also leaf area for each tree. Cohen and Naor (2002) determined that average LAI of Golden Delicious apple variety grafted on M9 rootstock M9 was 2.4 m 2 m -2 . Uçar et al. (2009) reported that the values of Galaxy Gala and Top Red apple varieties grafted on M9 rootstock ranged between 0.11 and 0.94 m 2 m -2 . Because of different apple variety, rootstocks and planting distances used in the study, values were different from this study.

Trunk cross-sectional area (TCSA)
According to results of TSCA values obtained from the study, it was observed that these values were continuously increasing each year after planting. Black textile had the highest values and the lowest values were obtained from the control treatment. Shoot development of fruit trees increased at young apple orchard when mulch materials were used and this increasing affected positively to trunk diameter increasing (Buban et al., 1996). Also frequent irrigation had a positive effect on trunk cross-sectional area. It is possible to said that the vegetative development increased in 1 st irrigation program with more frequent irrigation. Vegetative development of fruit trees decrease when soil water at effective root zone of trees decreases (Uçar et al., 2009). Vegetative development was negatively affected as the irrigation interval increased (for 3 rd irrigation programs). Yazgan et. al. (2004) for young sweet cherry trees and Uçar et. al. (2009) for young apple trees also reported similar results.
Water saving was determined in the study and less irrigation water was used for apple growing without a negative effect on vegetative development. Strong vegetative development has a positive effect when the trees grown up to yield age. Vegetative development (shoot number, shoot length, shoot diameter, trunk cross-sectional area, leaf area index) increased continuously because apple trees were young. Vegetative development of apple trees in mulch treatments was higher than apple trees in control treatments. Black textile among mulch materials had the highest vegetative development. Rose oil processing wastes and wheat straw mulches generally had similar results. Researchers reported that mulch materials increased shoot diameter, shoot length and shoot numbers of fruit trees (Kviklys et al., 2004;Phadung et al., 2005). The soil water was preserved at effective root zone for a longer period with mulch materials. Therefore, apple trees spent less energy during water intake with their roots (massive water intake) and as a result they had a higher vegetative growth and development. Neilsen et. al. (2003) and Hogue et. al. (2005) obtained similar results.
It was determined that mulching and irrigation programs had both positively effects on vegetative development and water saving for young apple orchards. Irrigation is recommended when %20 of available water holding capacity at effective root zone (0-90 cm) is consumed (1 st irrigation program) for young apple trees grafted on MM106 rootstock. Recommended irrigation is the 1 st irrigation program when the available water resources are sufficient. In addition, apple growers can use 2 nd irrigation program together with mulch materials when water resources are scarce. 22.0 and 31.3% in average water saving was obtained in mulch treatments. The highest water saving values were determined in black textile treatments as 23.5-31.3%. Accordingly, irrigation for more agricultural area may be provided with mulch using when water resources are also sufficient. Irrigation interval could be expanded with mulch using and a reduction of labor, energy cost etc. cost items was occurred by using less water. At the orchards where organic mulch materials such as wheat straw and rose oil processing wastes are used; completion of the missing thicknesses may be recommended at the end of every growing season to continue the effectiveness of mulches. According to the current status or at the regions where water resources are limited; the mulch and irrigation programs determined with this study may be recommended to apple growers.