Investigation of Bean Response to Application of Zinc in Some Soils of Markazi Province

Soil testing has an important role in proper management of plant nutrition in the field. Recommendations based on soil testing results are regional, therefore, these tests and calibrations must be carried out for each specific climatic condition. Bean (Phaseolus vulgaris L.) is one of the most widely grown crops in Markazi province and has high nutritional value for human. Because of lack of information about zinc critical levels and regional calibration, this study was conducted in Markazi province. Twenty soil samples  from different zones of the province were taken from the surface layer with wide range of soil properties and Zn concentration and were prepared for greenhouse cultivation of bean. Greenhouse experiment was conducted as complete randomized design with three replications. Treatments included two levels of zinc (0, 10 mgkg^-1 soil). At the end of vegetative stage, plants were harvested and prepared for laboratory analysis.  Analysis of variance results showed that effects of soil type and fertilizer were significant on dry matter weight (DMW), Zn concentration, and uptake. Interaction effects of soil and fertilizer were significant on DMW, zinc concentration, and uptake. Results of Duncan multiple range test showed that fertilizer application caused significant differences on DMW, and plant Zn concentration and uptake. Zinc critical level was determined by Cate–Nelson graphic method at 8 mg Zn kg^-1 soil (DTPA extraction method). Regression equation showed that available zinc was significantly related to organic carbon content and calcium carbonate equivalent. Relative yield showed significant relation with soil available zinc. Coefficient ‘c’ in Mitscherlich–Bray equation was 0.87. Critical level of soil available zinc at 80%, 85%, and 90 % of bean relative yield was obtained as, respectively, 0.8, 0.95, and 1.14 mg Zn kg^-1 soil.