Leaf Nutrient Concentrations of Apple Orchards in Isparta Province *

This study was conducted in Isparta province to investigate the mineral nutritional status of apple orchards by means of leaf analysis. For this purpose, seven districts were chosen and ten orchards from each district were selected. Leaf samples were taken during two years from the chosen trees. Leaf analyses results indicated that there was no Mg deficiency in trees. Similarly 97% of orchards did not show N deficiency. The most important nutritional problem was Zn nutrition, and 80% of the orchards showed Zn deficiency. On the other hand, 69, 64, 24 and 11% of the orchards showed P, Ca, K and Mn deficiencies, respectively. Finally, it was concluded that soils were fertilized sufficiently with N, but some important nutritional problems continued. Therefore; special fertilization programs should be applied for other nutrients specially for Zn, P and Ca as well.


Introduction
In plant production, productivity and quality are closely related to nutrient concentrations of plant.To get optimum plant production, nutrient concentrations should be at sufficient level in plants.Nutrient availability to plants is controlled by numerous factors.Factors such as soil, environment and plant affect the mineral nutrition and nutritional status of plants (Marschner 1995).
Soil and leaf analysis methods are often applied to determine plant nutritional status.Leaf analyses methods are often used to determine total amount of nutrients and used for evaluating soil fertility status.With these methods, determined nutrient concentrations are compared to sufficiency level and evaluated.Because nutrient requirement changes among plant species and genotypes, critic levels indicating healthy plant growth may differ.Therefore, some standard values are used to interpret plant nutritional status.However; for evaluating nutritional status of apple trees some different values were reported by authors (Bould 1966;Jones et al. 1991;Bergmann 1992;Wichmann 1992).Because knowing nutritional status of a plant is important for healthy growth.So, nutritional programs depending on analyses results, should be applied.Therefore, leaf analyses have important place on the works trying to overcome plants nutritional problems (Katkat et al. 1994;Güleryüz et al. 1996;Başar et al. 1997;Sönmez et al. 1999;Feramuz et al. 1999;Topçuoğlu 2003).Alpaslan et al. (2001) collected leaf samples to determine the nutritional status of cucumber, tomato, eggplant and pepper grown under green house conditions and compared leaf nutrient concentrations to threshold nutrient levels to explain nutritional status of plants.Mordoğan and Ergun (2001) examined leaf and fruit nutrient concentrations, and they found significant correlation between fruit organic acid contents and nutrient concentrations.Turkey having 2.300.000tons apple production is ranked as 4 th in the world.Isparta province meets the 20% of this total production (FAO 2004 ).Despite the region has an important role in apple production, quality and yield are not satisfactory.One of the most important reason of this is insufficient and unbalanced nutrition of apple trees.
The aims of this study were to determine the nutritional status of apple trees using leaf analyses and to assist proper nutritional programs for the future activities.

Selection of orchards and sampling:
The study was conducted in Isparta province including 7 districts (Eğirdir, Gelendost, Yalvaç, Senirkent, Uluborlu, Keçiborlu and Atabey) in consecutive years (2002)(2003).For this purpose, 10 orchards provided by commercial farm planted with Starking and Golden Delicious were chosen.Trees (5 trees for each da.) from different points of the orchards were selected.Leaf samples were collected from current year's terminals in July representing whole tree from four sides for 2 years from the same tree.
Soil characteristics of research areas: Some characteristics of the soils taken from the research areas were given in Table 1.When the soil properties were evaluated by Ülgen and Yurtsever (1995) and Viets and Lindsay (1973), it was seen that 6% of the soils was neutral, 94% of was slightly alkaline and lime content of about 70% of the soils was higher than 15%.About 70%, 40% and 60% of the soils were insufficient in terms of organic matter, P and Zn, respectively.Potassium, Mg and Mn concentrations of the soils were sufficient.
Plant analysis: Leaf samples were washed thoroughly with fountain water, dilute acid (0.2 N HCl) and re-distilled water to remove surface residues then dried at 65 C 0 and grounded for nutrient analysis.Nitrogen concentration in samples was determined according to modified Kjeldahl method.In order to determine P, K, Ca, Mg, Zn and Mn concentrations, 1 g of leaf sample was dry ashed at 500 ± 50 0 C for 8 h, and the ash was dissolved in 4 ml of 3N HCl and filled up with re-distilled water.Phosphorus concentrations of leaf samples were measured by vanadate-molybdate colorimetric method.The other nutrients were determined by an atomic absorption spectrophotometer (Kacar 1972).
According to the results obtained, whole orchards in Atabey, Senirkent and Eğirdir were sufficient in Mn based on critical levels given by Jones et al. (1991).Similarly, most of the of orchards in Uluborlu, Keçiborlu, Yalvaç and Gelendost districts were found to be Mn-sufficient.When the region was examined generally, it was seen that 89% of the samples were Mn-sufficient and 11% was Mndeficient (Table 5).
When an evaluation was made based on adequate ranges of mineral nutrition of apple trees indicated by Jones et al. (1991) for two years results, it could be said that there were no any Mg deficiency in trees.This results show well correspondence with previous study conducted on soils (Erdal et al. 2004).Similarly 97% of N When an evaluation was made based on adequate ranges of mineral nutrition of apple trees indicated by Jones et al. (1991) for two years results, it could be said that there were no any Mg deficiency in trees.This results show well correspondence with previous study conducted on soils  (Erdal et al. 2004).Similarly 97% of N concentrations of orchards were found to be sufficient.This results did not show well correspondence with the soil analyses results (Erdal et al. 2004).Because, soil analysis results showed that organic matter content in experimental area was generally deficient.This results indicated that plants are sufficiently fertilized by N. In another study conducted by Demircan and Yılmaz (2005), it was reported that N containing fertilizer application was quite high in the region.The biggest nutritional problem observed was in Zn nutrition, and 80% of the orchards had Zn deficiency.And orchards having P, Ca, K and Mn deficiency were at 69, 64, 24 and 11%, respectively.Despite, nearly 70% of the region soils have high amount of CaCO 3 (> 15%), occurring Ca deficiency in a large area seems to be surprising.This findings indicates that there are some factors preventing Ca uptake by plant.In the literature, it is mentioned that there are several factors affecting Ca uptake.For instance, in-balanced watering, low transpireation rates and high soil pH negatively affect plants Ca uptake (Mix and Marschner 1976).Higher rate of Mg and sometimes K in the external solution might be another factor.Because Mg and K are easily carried in plant tissues, higher amount of these nutrients prevents plants from uptaking sufficient Ca.The other important factor leading to Ca deficiency in plants might be higher concentration of N, K and Mg in irrigation water (Güneş et al. 2000).In a study conducted in the region, over fertilization was determined for N and K (Demircan and Yılmaz 2005).

Conclusion:
It could be concluded that plants are sufficiently fertilized by N. Soil characteristics showed that pH was slightly alkaline and lime content was high.Because these factors affect mineral availability, especially Zn and P nutritional deficiency is inevitable.Therefore, specific attentions should be given to P and Zn fertilization.This problem may be dissolved by choosing proper fertilizer, fertilization type and fertilization time.Avoiding from applying nutrients which are sufficient in soil and plant prevents ion antagonism.Calcium is another nutritional problem in a wide area.Because Ca is one of the most important nutrient for plant growth and fruit quality especially under storage conditions, plant Ca concentration must be increased by any ways.Under unfavorable soil condition for nutrient availability, foliar applications or usage of chelated forms may overcome nutritional deficiencies.In same cases, dipping or spraying methods may be applied to increase fruit Ca concentrations before storage.

Table 1 .
Some characteristics of the soils taken from the research areas

Table 2 .
Leaf N, P and K concentrations of apple trees grown in Isparta province.

Table 3 .
Leaf Ca and Mg concentrations of apple trees grown in Isparta province.

Table 4 .
Leaf Zn and Mn concentrations of apple trees grown in Isparta province.