Effect of irrigation regime and application of kaolin on yield, quality and water use efficiency of sweet pepper

The present paper reports research that focused on the effect of kaolin on the yield, quality and water use efficiency of the sweet pepper Capsicum annuum L, grown under different irrigation regimes. The research was conducted in an open field with carbonate chernozem soil, at Stara Pazova (40 km north of Belgrade, Serbia). It lasted for three years (2011, 2012, and 2013). Three irrigation regimes and two kaolin treatments were compared. The irrigation regimes were: (i) full irrigation (F) ensuring 100% of crop evapotranspiration (ETc), (ii) deficit irrigation at 80% ETc (R1), and (iii) deficit irrigation at 70% ETc (R2). The kaolin treatments were: (i) control without kaolin (C) and (ii) treatment with kaolin application (K). The setup was a two-factorial, completely random block system, with three replications. The first factor was the irrigation regime and the second kaolin application. On average, the highest fresh sweet pepper yields were achieved under full irrigation (10 kg m(-2)). Also, FC and FK treatments resulted in the highest first-class, second-class and first + second class yields. On average, the lowest percentage of sunburn was noted in the case of the FK treatment (10%), and the highest with the R2C treatment (about 27%). The sugar content of the pepper was quite consistent, while the organic acid content varied from 15.0 mLg(-1) with R1C to 18.7 mLg(-1) with FK. The application of kaolin and the irrigation regime did not have a statistically significant effect on the antioxidant activity of the pepper and ranged from 5538.4 to 6447.4 p.mol TU g(-1). The highest yield water use efficiency (yWUE) of first-class and first+second class yields was recorded with the FC, FK and RIC treatments. Throughout the study period, yWUE levels of the second-class yields, and of the total yield, were rather uniform, regardless of the type of treatment