Interactive Effects of Boron and Humic Acid on the Growth and Nutrient Status of Maize Plant (Zea mays L.)

Development of the methods decreasing boron (B) toxicity to agricultural crops is a high priority. The use of alternative organic material sources such as leonardite based humic substances (H.A.) could be used to control B balance in soils. For this aim, a pot experiment, based on a completely randomized design with three replications, was conducted using the soil of calcareous usthochrepts. In the research, maize variety of ADA-9510 (Zea mays L.), which was obtained from Central Anatolia Region, was used. In the experiment, leonardite based humic substance (12% humic acid) at the levels of 0, 60, 120 mg kg-1 were used as humic material source, which was developed by Turkish Coal Corporations Foundation. Boron fertilizer at the levels of 0, 10, 20 and 30 mg B kg-1 were used in the form of H3BO3. The plants were harvested after 56 days, and dry weights in top of maize plants were recorded. Macro and micro nutrient concentrations of the plants were also determined. Dry matter yields of maize plants were significanly affected by the applications of H.A. and B fertilizer, whereas dry matter yield was decreased by the application of higher B at the rate of 30 mg kg-1 without H.A application. Thus, results of this study clearly showed that there was a close sinergism between the H.A. and B applications with regard to B toxicity tolerance of maize plants. The maximum dry matter yields of 50.71 and 51.09 g pot-1 were obtained by the applications of 20 mg B kg-1together with H.A. applications at the rates of 60 and 120 mg kg-1, respectively. Depending on H.A. applications, B contents of maize plants varied between 32.18 and 35.02 mg kg-1.