Effect of calcium based fertilization on dried fig (Ficus carica L. cv. Sarılop) yield and quality

Effect of calcium based fertilization on dried fig (Ficus carica L. cv. Sarılop) yield and quality

Scientia Horticulturae 118 (2008) 308–313 Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate...

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Scientia Horticulturae 118 (2008) 308–313

Contents lists available at ScienceDirect

Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti

Effect of calcium based fertilization on dried fig (Ficus carica L. cv. Sarılop) yield and quality Mehmet Es¸ref I˙rget a, Uygun Aksoy b,*, Bu¨lent Okur a, Ali Rıza Ongun a, Mahmut Tepecik a a b

Ege University Faculty of Agriculture, Department of Soil Science, 35100 Bornova-I˙zmir, Turkey Ege University Faculty of Agriculture, Department of Horticulture, 35100 Bornova-I˙zmir, Turkey

A R T I C L E I N F O

A B S T R A C T

Article history: Received 17 December 2007 Received in revised form 14 May 2008 Accepted 13 June 2008

Fig tree mainly spread in regions where Mediterranean climate prevails can be grown over a wide range of soils without any significant deficiency or toxicity symptoms of plant nutrients. Surveys revealed that, however, quality is highly affected by nutrition especially N, K and Ca in fig production for commercial drying. This research work was initiated based on few studies performed on fertilization of fig. The experiment was performed between 2000 and 2002 in three fig orchards of cv. Sarılop (syn. Calimyrna) in Aydın-Turkey. Trees received seven types of fertilization as (i) untreated control; (ii) NPK (430 g N, 200 g P2O5 and 430 g K2O per tree); (iii) NPK + 70 g Ca; (iv) NPK + 140 g Ca; (v) NPK + 280 g Ca; (vi) NPK + 420 g Ca and (vii) N + 420 g Ca, Ca(NO3)2 used as the Ca source. Tested fertilizer applications showed significant differences in respect to yield and quality of fig. Basic NPK fertilization with additional 280 g Ca treatment increased overall quality by reducing the number of fruit with ostiole-end crack and sunscald. Results showed that applied fertilizers exerted significantly in reduction of cull ratio and could alleviate the negative impact of yearly drought conditions. ß 2008 Elsevier B.V. All rights reserved.

Keywords: Fig Fertilization Calcium Fruit quality Yield Sunscald Ostiole-end crack

1. Introduction The fig tree (Ficus carica L.) is one of the unique Ficus species widely spread in tropical and subtropical countries which has edible fruits with high commercial value. Commercial fig production is either located around the Mediterranean Sea or is realized in countries possessing Mediterranean climate as in the case of California, Australia or South America. In Turkey, the major fig producer, around 65% of fig trees are in the western Aegean Region especially in Small and Big Meander valleys. The major variety grown in this region is Sarılop (syn. Calimyrna) which is commercially sun dried (Aksoy et al., 1987, 2001). Sarılop variety is known world-wide for its superior dried fruit quality. Climatic conditions prevailing in the Meander Basin especially in summer during fruit maturation and drying period play a crucial role on final quality. As a consequence, in the Meander Basin almost all fruit go for sun-drying whereas fig fruits produced in other regions are sold for the fresh market (Aksoy et al., 1987, 2001). Until the 1950s, fig occupied lowland orchards however after the introduction of irrigation fig trees were replaced by high value crops.

* Corresponding author. Fax: +90 232 388 18 65. E-mail address: [email protected] (U. Aksoy). 0304-4238/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2008.06.024

Currently, most of the orchards are located on slopes and fig is produced as low-input system under rain-fed conditions. Very little research work has been carried out world-wide on fig tree fertilization (Proebsting and Warner, 1954; Hernandez et al., 1994). Taking this into consideration, some of the results obtained in these research papers are summarized. Aksoy (1981) reported that N, P, K and Ca concentration decreased from the initial stage of fruit growth up to the end of the harvesting period. Kabasakal (1983) recommended beginning of the fruit maturation period for sampling fig leaves as the most stable period in respect to nutrients. Brown (1994) examined seasonal variation of plant nutrients in Calimyrna (Sarılop) variety and reported reduction in N, P and K concentrations through out the season whereas increases in Ca and Mg. Aksoy and Anac¸ (1994) applied CaCl2 (1%) as foliar spray towards the end of the secondfruitgrowth period on trees of three fig varieties, Bursa Black, Go¨klop and Sarılop known to have variable tendency for ostiole-end cracking as resistant, susceptible and intermediate, respectively. CaCl2 application decreased crack ratio significantly in Go¨klop and increased sunscald slightly in Sarılop variety. Moreno et al. (1998) determined the minimum, optimal and maximum levels of N, P, K, Ca, Mg and S in fig leaves in a 4-year research carried out in Granada-Spain.

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I˙rget et al. (1999) examined foliar application of Ca, K and K + Ca in nitrate form on fruit quality of Sarılop variety. Potassium application affected fruit size, colour and firmness positively and Ca application decreased ostiole-end cracks. Hakerlerler et al. (1999) applied six levels of ZnSO47H2O ranging between 0 and 600 g as soil and five levels (0.0–0.2%) as foliar application. The applications had significant effects on yield, lamina Zn concentration, shoot length and fruit quality especially on colour and sugar content. S¸ahin (2003) evaluated aflatoxin and ochratoxin A formation in dried figs produced in Big and Small Meander basins and proposed that toxin formation was significantly related with fruit size and sunscald. Most of the other research work on fig nutrition is based on surveys monitoring nutritional status of fig trees (Aksoy et al., 1987; Anac¸ et al., 1987, 1992; Eryu¨ce et al., 1987; Du¨zbastılar and Gu¨lec¸, 1995; As¸kın et al., 1997), and few evaluated their relationship with fruit yield and quality (Aksoy et al., 1987; Anac¸ et al., 1992). Studies carried out in Turkey revealed nutrition related problems especially in respect to N, K, Ca and B. Aksoy et al. (1987) and Anac¸ et al. (1992) reported as a conclusion of surveys that K enhances fruit taste and colour, reduces sunscald in fruits, but excess levels promote ostiole-end crack/split in fruits, whereas Ca reduces ostiole-end crack, but in case of excess triggers sunscald, reduces fruit size and darkens fruit colour. Sunscald and ostiole-end cracks are accepted as defects if they go over 1/3 of the surface area or length, respectively according to the Turkish dried fig standard (TS 541). Defected fruits are removed from parties destined for human consumption and thus increase the cost. Even if the area affected by sunscald is negligible, it may modify the taste and palatability and cracks may provide additional entrance for insects and fungi. Taking into consideration marked effect of Ca nutrition on yield and quality of Sarılop (Calimyrna) fig variety, a research was designed to test the effects of additional soil Ca application combined with a basic dressing composed of N, P and K or N alone on.

309

growing district in western Turkey. The experimental orchards have typic Xerofluvent (alluvial) soils. Data related to the experimental sites and physical and chemical soil properties are displayed in Tables 1 and 2, respectively. The climatic condition prevailing in the experimental site is typical Mediterranean climate with dry and hot summers and mild and rainy winters. The annual rainfall calculated for 1999–2000 season (October–June), 2000–2001 and 2001–2002 are 512.0, 436.6 and 778.7 mm, respectively. The precipitation during the fruit growth period (July–September) were 20.3, 2.7 and 96.0 mm in 2000, 2001 and 2002 summers, respectively. 2.2. Fertilization programmes and experimental design The experiment was designed as randomized blocks with three replicates, each replicate possessing two trees. The tree vigour was almost similar, and the average canopy diameter was 6.81 m in Kanlıbahc¸e and 5.95 m in Erbeyli. The treatments tested in the experiment are as follows: (1) (2) (3) (4) (5) (6) (7)

control (no treatment), NPK, NPK + 70 g Ca, NPK + 140 g Ca, NPK + 280 g Ca, NPK + 420 g Ca, N + 420 g Ca.

All trees, except untreated control (1st) and the 7th treatment, received N, P and K at levels fixed as 430 g N/tree; 200 g P2O5/tree and 430 g K2O/tree. The 7th treatment was included to investigate the combined effect of Ca and N under the absence of additional P and K. As Ca source Ca (NO3)2 (15.5% N + 26% CaO), as N source Ca (NO3)2 and NH4NO3 (33% N), as P source DAP (18-46-0) and as K source K2SO4 (0-0-50) was used. Fertilizers were applied yearly as two parallel lines on all four sides of the tree at a depth of 10–15 cm during the period between end-February to mid-March. To avoid mixing of fertilizers, fertilizer containing Ca was applied to one line, and N, P and K fertilizers to the second line.

2. Materials and methods 2.3. Data collection and statistical analysis 2.1. Experimental material and conditions Partially shrivelled fig fruits falling onto the ground from each tree were collected separately and further dried on drying trays. Cull fig fruits defined as defected in Turkish TS 541 (Anonymous,

The trial is carried out in 3 Sarılop (syn. Calimyrna) fig orchards between 2000 and 2002 in two locations in Aydın, the major fig Table 1 Background information related to the experimental orchards Location 1. Kanlıbahc¸e

Geographic location 0

00

37851 57 1N

Tree age

Tree training

Irrigation

Fertilization

Initial conditions/problems

>60

Multitrunk

1–2 times

Only N fertilizers

Yield moderate, internal rot, darkening of fruit colour right after harvest

>30

Single trunk

Rain-fed

None

High cull ratio

278350 0400 7E 2. Erbeyli

378510 5300 1N 278390 5600 0E

Table 2 Soil properties of fig orchards located in Kanlıbahc¸e in Germencik (1) and in Erbeyli (2) (Aydın/Turkey) Location

Soil depth (cm)

Texture

pH

CaCO3 (%)

CEC (cmolc kg1)

OM (%)

TotalN (%)

P (mg kg1)

K

Ca

Mg

(1) Kanlıbahc¸e

0–24 49–75

Sandy loam Loam

7.04 7.50

0.55 3.53

14.84 24.16

1.52 1.68

0.084 0.067

1.20 0.67

167 137

2071 3684

356 472

(2) Erbeyli

0–20 60–80

Sandy loam Sand

7.54 7.85

1.07 2.72

11.74 4.14

0.67 0.21

0.031 0.028

2.95 1.18

134 33

1714 437

235 174

P: water extractable P by the Bingham; OM: organic matter; K-Ca-Mg: 1N NH4OAc pH 7; CEC: cation exchange capacity.

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310 Table 3 Quality classes in evaluating sun-scald and crack index Class

Crack

0 1

None Slight

No cracking Less than 1/3 of fruit length

None Slight

No sunscald Sun scalded area less than 1/3 of fruit surface

2

Medium

Between 1/3–2/3 of fruit length

Medium

Area between 1/3–2/3 of fruit surface

Severe

More than 2/3 of the fruit surface

3

Severe

Sunscald

0

More than 2/3 of fruit length

2006) and UN/ECE Dried Fig Standards (Anonymous, 2004) were removed and weighed. Total yield per tree was calculated at the end of the season. Marketable yield was calculated as the difference between total yield and cull figs. Cull ratio was calculated as cull/total fruit yield. The number of trunks and canopy diameters were also determined to assess tree vigour. Fruit samples were taken during the harvest period, and physical parameters as average fruit weight (g), cracked (split) or sun scalded fruit ratios were analyzed on 15–20 fresh fruit samples taken per tree. Fruit maturation was monitored in all trees in both years. Two trained panelists evaluated ostiole-end crack (split) and sun scalded fruit ratio twice during the harvest period, and the results are expressed as the average of the two. Evaluation of crack and sunscald rate was made visually according to the 0–3 scale (Table 3) and average index values were calculated according to the numbers of fruits in each quality classes. The trials were set up in three orchards, two of which were located next to each other in Kanlıbahc¸e/Germencik (location 1) yielding similar effects therefore average was taken for two years in 2000 and 2001. A parallel trial was performed in Erbeyli, as the third orchard in 2001 and 2002 (location 2). Analysis of variance was applied to data obtained separately in each location for two years and averages calculated for each location were compared by Tukey test (p  0.05) using SAS program (SAS, 2006).

year irrespective of the location. In 2001, total yields were reduced by 26.0 and 19.1%, respectively in Kanlıbahc¸e and Erbeyli compared to other years of the experiment.

3. Results and discussion

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey

3.1. Total and marketable yield The tested treatments yielded significant differences in respect to total and marketable dried fig yields. 3.1.1. Total yield In both locations, the lowest yields were obtained in untreated control trees as 26.38 and 15.84 kg/tree (Table 4). On the other hand, the highest yields were obtained with NPK application as 30.87 kg/tree in Kanlıbahc¸e and NPK + 280 g Ca applications in Erbeyli as 20.92 kg/tree. NPK + Ca or N + Ca applications did not have any additional affect on yield in both locations except NPK + 280 g Ca in Erbeyli. The average yield values in both locations were within the limits reported by Hakerlerler et al. (1999) as 14.5 and 22.1 kg/tree. There are many factors known to affect fruit yield and quality in fig trees as soil, climatic conditions, cultural practices, e.g. pruning, irrigation, fertilization, plant protection and caprification (Aksoy et al., 2001). In Sarılop variety caprification is the major factor affecting fruit set and thus yield, however, shoot length and number of buds per shoots are reported to be related with yield (Aksoy et al., 1987; Anac¸ et al., 1992). Based upon the correlations obtained in surveys, the researchers mention that nitrogen triggers shoot growth and tree vigour, increases number of fruits but in case of excess levels, reduce fruit quality. The results of the experiment support these findings that point out the key role of nitrogen in respect to total yield. Yearly conditions had marked effects and the yields obtained in 2001 were lower than the other

3.1.2. Marketable yield The lowest marketable yield values as it is for the total yield were obtained in control parcels as 21.60 and 10.94 kg/tree (Table 5) in Kanlıbahc¸e and Erbeyli, respectively. The highest marketable yields were in NPK treatment in Kanlıbahc¸e (26.91 kg/ tree) and in NPK + 280 g Ca (16.57 kg/tree) treatment in Erbeyli. N + Ca application alone improved marketable yield compared to control in both locations. In respect to marketable yield, the difference among treatments other than the control was not statistically significant in Kanlıbahc¸e. In Erbeyli, Ca application ranging between 70 and 420 g/tree in addition to NPK resulted in significantly higher marketable yields compared to control, NPK and N + Ca applications. The varying responses to the treatments between the two locations can be due to the different soil properties. As presented in Table 2, the organic matter, CEC, total N, Table 4 Total dried fig yield (kg/tree) obtained with tested treatments Treatment

Year 1 Year 2 Tukey Year  treatment (p > F)

Total Yield (kg/tree) Kanlıbahc¸e

Erbeyli

26.38 30.87 29.44 29.31 29.28 30.71 29.70 3.35

15.84 17.87 18.51 20.43 20.92 19.19 18.21 2.89

b a ab ab ab a ab

c bc abc ab a ab abc

33.76 a (2000) 25.00 b (2001) 1.74

16.85 b (2001) 20.57 a (2002) 1.00

ns

ns

Table 5 Marketable yield (kg/tree) obtained with tested treatments Treatment

Marketable yield (kg/tree) Kanlıbahc¸e

Erbeyli

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey

21.60 26.91 25.59 25.49 25.63 26.86 25.92 3.12

10.94 13.41 14.65 16.19 16.57 15.29 13.86 2.36

Year 1 Year 2 Tukey Year  treatment (p > F)

b a a a a a a

d c abc ab a abc bc

30.83 a (2000) 20.13 b (2001) 1.093

12.18 b (2001) 16.64 a (2002) 0.82

ns

ns

M.E. I˙rget et al. / Scientia Horticulturae 118 (2008) 308–313 Table 6 Average fruit weight (g)

311

Table 7 Average ostiole-end crack index calculated according to 0 to 3 scale

Treatment

Average fruit weight (g) Kanlıbahc¸e

Erbeyli

Kanlıbahc¸e

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey

16.15 17.02 16.54 16.81 17.14 16.92 16.85 ns

14.43 15.02 16.48 16.02 16.24 15.50 15.65 1.00

Mean

2001

2002

Mean

16.98 (2000) 16.78 (2001) ns

15.18 b (2001) 16.05 a (2002) 0.35

1.50 1.40 1.32 1.37 1.33 1.29 1.21 0.15

1.33 1.17 0.92 0.83 0.92 1.17 1.21 0.41

1.78 1.54 1.25 1.13 1.13 1.05 1.00 0.41

1.56 1.36 1.09 0.98 1.02 1.11 1.11 0.31

ns

ns

Year 1 Year 2 Tukey Year  treatment (p > F)

Treatment

c bc a ab a ab ab

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey Year 1 Year 2 Tukey Year  treatment (p > F)

available K and Ca contents are lower in Erbeyli compared to Kanlıbahc¸e especially below 20 cm depth, around the root zone. This data emphasizes the need to evaluate site specific conditions especially soil properties thoroughly prior to any further recommendations regarding plant nutrition. In Kanlıbahc¸e, average marketable yield was 30.83 kg/tree in 2000 and decreased by 34.7% to 20.13 kg/tree in 2001. In Erbeyli, there was a 26.80% difference in marketable yield obtained between 2001 and 2002. 3.2. Fruit quality Fig fruit quality was assessed by determining the average fruit weight, ratios of fruit with ostiole-end crack or sunscald and cull fruit ratio. 3.2.1. Average fruit weight Tested treatments had marked effects on average fruit weight in Erbeyli, and additional Ca increased fruit weight compared to control, however, the impact was not statistically significant in Kanlıbahc¸e (Table 6). In both trials, the untreated control parcels gave the smallest fruit weight with 16.15 g in Kanlıbahc¸e and 14.43 g in Erbeyli. Largest fruit were obtained by the addition of Ca as 280 g to NPK in Kanlıbahc¸e (17.14 g/fruit) and as 70 g in Erbeyli (16.48 g/fruit). The average fruit weight of Sarılop dried fig fruits is reported to range between 10.2 and 28.2 g (Aksoy et al., 1987; Anac¸ et al., 1992; S¸ahin, 2003). Dried fruit weight varies in Sarılop cultivar according to the number of fruits on the tree, yearly climatic conditions or cultural practices applied (Aksoy et al., 2001). Dried fruit size is the major factor in determining price of dried fig fruits especially for direct consumption. In both locations, average fruit weight was decreased at Ca levels exceeding NPK + 280Ca therefore addition of Ca around this optimum level can be recommended to obtain higher fruit weight and thus higher prices. Yearly conditions also put forth significant effects on fruit size in Erbeyli, larger fruits (16.05 g) being obtained in 2002 compared to 2001 (15.18 g) (Table 6). 3.2.2. Ostiole-end crack Tested treatments and yearly conditions had significant effects on fruit with ostiole-end crack. In both experiments, the lowest crack index was obtained with treatments containing Ca in both years and locations (Table 7). This result can be attributed to the role of Ca on stability and integrity of the cell wall (Marschner, 1995). Fruit internal factors, various biotic, genetic, skin abnorm-

Ostiole-end crack/split index

a ab bc b bc bc c

Erbeyli

a a b b b ab ab

a ab bc c c c c

1.36 b (2000) 1.58 a (2001) 0.06

1.08 b (2001) 1.27 a (2002) 0.13

ns

0.05*

a ab bc c c bc bc

alities, environmental or cultural factors are also known to affect fruit cracking (Opara et al., 1997). Cracking is not yet fully investigated in fig fruits, however, previous studies based on observations and surveys display that ostiole-end cracking of fig fruit is linked with variety, climatic conditions, soil properties (lime and available Ca content) and nutritional status, especially Ca (Aksoy et al., 1987, 2001). Shear (1971) also reported that deficiency of Ca and B may lead to development of fruit crack, while high N would intensify the disorder. Soil Ca applications are generally regarded as insufficient to increase fruit Ca concentration, thereby in overcoming physiological disorders related to Ca (Mengel and Kirkby, 2001; Poovaiah et al., 1988; Bangerth, 1979). Ca related metabolic disorders are attributed to uneven distribution of Ca within the plant rather than Ca uptake by the plants. As a consequence, in general foliar Ca applications are recommended rather than soil applications. The results obtained regarding the increases in fruit Ca concentration and consequent reduction in ostiole-end cracks through soil Ca applications point out that fig fruit can be highly responsive to soil available Ca or benefit from soil Ca applications by higher extraction and translocation capacity. This can be a case specific for the fig tree since fig fruit is known to be highly rich in Ca compared to other fruits (Anonymus, 2002; Aksoy et al., 1987; Anac¸ et al., 1992), thus it is worth to investigate calcium nutrition of fig fruit more in depth in order to contribute to other fruit species, as well. The additional additive effects of Ca application in the following years in Table 8 Average sunscald index calculated according to 0–3 scale Treatment

Sunscald index Kanlıbahc¸e

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey Year 1 Year 2 Tukey Year  treatment (p > F)

Erbeyli

Mean

2001

1.73 1.49 1.54 1.59 1.66 1.70 1.74 0.15

1.92 1.83 1.58 1.67 1.83 1.75 1.92 0.32

a c bc ab ac a a

2002 a ab b ab ab ab a

1.71 1.38 1.25 1.38 1.21 1.21 1.46 0.32

Mean a b b b b b ab

1.55 b (2000) 1.72 a (2001) 0.10

1.79 a (2001) 1.37 b (2002) 0.15

ns

0.01**

1.82 1.61 1.42 1.53 1.52 1.48 1.69 0.21

a ab b ab ab ab ab

M.E. I˙rget et al. / Scientia Horticulturae 118 (2008) 308–313

312 Table 9 Leaf and fruit Ca and K concentration in Erbeyli Treatment

Leaf

Fruit

K (%)

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey Year 1 Year 2 Tukey Year  treatment (p > F)

Ca (%)

K (%)

2001

2002

2001

2002

0.54 0.65 0.62 0.66 0.66 0.67 0.61 0.10

0.66 0.98 0.80 0.88 0.99 0.92 0.70 0.14

5.62 5.54 5.67 5.98 5.63 6.06 6.08 0.44

5.78 5.62 5.81 6.24 6.14 6.33 6.72 0.44

b a ab a a a ab

d a bc ab a ab cd

0.63 b (2001) 0.85 a (2002) 0.05 0.01**

cd d abcd abc ab ab a

5.80 b (2001) 6.04 a (2002) 0.17 0.05*

preventing fruit crack needs to be considered, as well. Together with Ca, the impact of B shall be investigated in future studies. 3.2.3. Sunscald In Kanlıbahc¸e, fruits receiving NPK alone were the least affected. Sunscald index increased with the increasing Ca levels added to NPK. Control and N + 420 g Ca treatments had the highest sunscald index in both locations (Table 8). Similarly, the highest index values were found in control and N + Ca in Erbeyli. The difference between the years was significant in both locations yielding higher sunscald index in 2001. The actual mechanisms of sunscald of fig fruit need further investigation as it is with fruit cracking. The results of surveys and on-going researchwork disclose significant effect of soil properties and aspect (light intensity) on sunscald. In this respect, soil available potassium content seems to be effective on sunscald incidence, and K applications prevented or reduced the defect. In Erbeyli, application of NPK enhanced fruit K content significantly, whereas, addition of Ca to NPK decreased fruit K levels (Table 9). These findings support previous results showing positive correlation between sunscald and fruit K concentration and negative correlation with fruit Ca (Aksoy et al., 1987; Anac¸ et al., 1992). The results also signify the importance of the balance between K and Ca in respect to sunscald. Previous findings put forward higher incidence of sunburn among fruits facing south or those that are under direct and intensive sun, and thus lead to the assumption that sunburn can be due to photooxidative damage (Cakmak, 2007). Brown (1994) also Table 10 Cull fruit ratio (%) obtained in tested treatments Treatment

1. Control 2. NPK 3. NPK + 70 g Ca 4. NPK + 140 g Ca 5. NPK + 280 g Ca 6. NPK + 420 g Ca 7. N + 420 g Ca Tukey Year 1 Year 2 Tukey Year  treatment (p > F)

Cull ratio (%)

2002

2001

2002

1.01 1.13 1.01 1.00 1.05 1.02 1.08 0.12

0.98 1.25 1.12 1.07 1.14 1.08 0.98 0.16

0.31 0.30 0.30 0.32 0.31 0.30 0.32 ns

0.30 0.29 0.34 0.34 0.36 0.35 0.36 0.04

ab a ab b ab ab ab

1.04  (2001) 1.09  (2002) ns ns

b a ab b ab b b

b b a a a a a

0.31 b (2001) 0.33 a (2002) 0.01 0.05*

reported that sunscald significantly reduces quality of figs in California, although the association between fig sunscald and leaf K concentrations has not been investigated. 3.2.4. Cull ratio The highest overall fruit quality was obtained with addition of Ca to NPK, 280 g in Kanlıbahc¸e and 420 g in Erbeyli Ca due to low cull ratio. In Kanlıbahc¸e, cull fruits totalled to 2.91 kg/tree (8.81%) in 2000 and to 4.87 kg/tree (19.66%) in 2001. In Erbeyli, cull fruits were 4.66 kg/tree (27.94%) in 2001 and 3.93 kg/tree (19.34%) in 2002. In both years and locations, control trees possessed the lowest dried fig quality with highest cull ratio (Table 10). Studies carried out in dried fig orchards in Small and Big Meander Basin reported cull ratios ranging between 13.30 and 89.12% (Anac¸ et al., 1992), 28.6–30.4% (Aksoy et al., 1987) and 4.59–31.17% (S¸ahin, 2003). The cull ratios obtained in the experiment are in the lower end of the results of the previous surveys. Total yield and cull ratio were affected especially by the lack of rainfall during the period between October and June in 2001. This effect was more pronounced than the negative effect of rain during fruit maturation and drying period as experienced in 2002. Under drought conditions nutrient uptake and translocation are reduced leading to higher sunscald incidence (Nilsen and Orcutt, 1996). Drought also favours sunscald of fruits due to early leaf fall that leads to direct exposure to sun. Ca addition to NPK seemed to reduce the impact of drought stress and sunscald and crack incidence and thus resulted in lower cull ratio (Table 10). The effect of applied nutrients especially of Ca continues in the consequent years. Observations performed in the following years in the experimental orchards revealed decreased ostiole-end crack and cull ratios supporting this view. 4. Conclusion

Kanlıbahc¸e

Erbeyli

19.56 13.72 14.35 12.75 12.74 13.43 13.10 2.86

31.21 25.57 21.17 21.41 21.28 20.47 24.36 3.27

a b b b b b b

cd d bcd ab abc a a

Ca (%)

2001

a b cd cd cd d bc

8.81 b (2000) 19.66 a (2001) 1.00

27.94 a (2001) 19.34 b (2002) 1.13

0.01**

ns

The results obtained proved that tested treatments play a major role to obtain high yield and quality in Sarılop fig production. Fertilization with NPK alone or in combination with Ca increased the total yield in both experiments. Addition of Ca up to a certain level to basic NPK fertilization enhanced fruit quality by increasing average fruit weight and lowering cull ratio through reduced sunscald and ostiole-end crack incidence. Together with basic NPK fertilization Ca addition to the soil at a range of 280 and 420 g Ca/ tree is recommended taking into consideration its effect on sunscald and further effects in consequent years. As a consequence of appropriate fertilization, profitability can be advanced through higher yields and higher farm prices. The results also show that site

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