An Evaluation of Carbohydrates and Nutrient Content of some Young Asian Pear (Pyrus serotina Rehd.) Cultivars on European Pear (Pyrus communis L.) Seedling Rootstocks under Isfahan Environmental Conditions

In line with an investigation regarding to evaluation of the compatibility of the Asian Pear cultivars with Iran climatic conditions – currently being carried out at the Horticultural Department of Tarbiyat Modares University (TMU) – the present preliminary study was performed in two regions in Isfahan. Asian pear (Pyrus serotina Rehd.) cultivars (grafted on European pear seedling rootstocks) were evaluated at three main vegetative growth stages for leaf N, P and K and total soluble carbohydrates during 2008 growing season under Pirbakran, Isfahan environmental conditions. In addition, the same assessments were carried out destructively on harvested samples of roots and aerial parts of budded trees (shoots and leaves) during 2009 growing season under Kabootarabad of Isfahan climatic conditions. Results revealed significant differences among the studied Asian pear cultivars in which they also showed a better performance in comparison with local Shahmiveh and Sebri pears. Significant differences were also observed among the studied cultivars as regards leaf mineral analysis of N, P and K and soluble carbohydrate during both seasons and under both experimental sites. From the beginning to the end of the growing season, N and P of leaf were decreased while K concentration being significantly increased. Leaf soluble carbohydrates showed significant differences for the three sampling stages. On the other hand, leaf soluble carbohydrate in the first season (2008) from the beginning to mid-season increased while starting to decrease until the end of the season, although, the level of leaf carbohydrates decreased until the mid-season during the second growing season (2009), then started to increase until the end of the season. It seems that roots were the major storage organ for carbohydrates, in which soluble carbohydrate of shoots, roots as well as P and K in the roots showed a reduction during the growing season. The level of shoot N and K decreased, while the content of shoot P decreased first and then increased during the growing season. In addition, there was an increase observed in root N during the growing season.