Selection of suitable extractant to extract available iron in peach in soils of Golestan Province

Iron-chlorosis is an important problem in peach trees in calcareous soils of Iran and affects over 60% of Iranian soils. In order to assess the status of iron and evaluation of common extractants used for the extraction of available iron for peach in orchard soils of Golestan province, 39 major soils and depths of 0-30 and 30-60 were selected and on the basis of tests and iron extracted with DTPA, 24 soils were selected for further studies. The iron was extracted by DTPA, AB-DTPA, Hydroxyl amin hydrochloride and Mehlich1. In garden studies of the various varieties of peaches that were under chlorosis the benchmark plant and three levels of treatments (Fe0, Fe1) of iron sequestrine-138 (6%) source in 0 and 10 Kg/he rates utilized in split plot experiment with four replications. The results based on the amount of iron extracted by DTPA and AB-DTPA extractant shows significant relationship with chlorophyll concentration in plants. Also Hydroxyl amin hydrochloride extractant showed a significant correlation with total iron concentration. The AB-DTPA was selected as the best extractant, because of its high correlation with chlorophyll content as well as being easy and economical. Also the critical level of iron was determined on the basis of Cate-Nelson GM with AB-DTPA for relative total iron concentration, active iron concentration and chlorophyll meter index was 13, 14 and 13 mg/kg, respectively.