Research PaperAdvances in the study of nitrification inhibitor DMPP in strawberry

- The main purpose of this study was to evaluate the effect of DMPP on yield, nutritional and fruit quality in strawberry.
- Treatment with DMPP increased the antioxidant compounds content such as vitamin C (AsA) and total phenolics.
- Additional advantages of DMPP treatments used in this experiment are its high plant compatibility (no phytotoxic damage).
- The application of nitrification inhibitors can increase the efficiency of fertilizer use

DMPP (3,4-dimethylpyrazole phosphate) is an efficient nitrification inhibitor, thus increasing nitrogen (N) fertilization efficiency, crop yield and fruit quality. The aim of this study was to evaluate the effect of DMPP on yield, nutritional and organoleptic quality and chlorophyll fluorescence in strawberry plants. The experiment was carried out in a greenhouse in Huelva (Spain) between October 2013 and June 2014 on one type of strawberry (Fragaria x ananassa Duch. cultivar 'Sabrina'). A completely randomized design with three N treatments and five replicates was established. The number of plants used per treatment was 50 (10 plants per replicate, i.e. a total 150 plants were used). The following N treatments were tested: T1: 100% of N in ammonium nitrate form; T2: 75% of N in Novatec solub 21 form (ammonium sulphate + DMPP) + 25 % of N in ammonium nitrate form; T3: T2, but applying 75% of total N. Results show that the total yield per pot of the 'Sabrina' cultivar yield was affected by N treatment and crop cycle (weeks of harvest). During the total crop cycle, the yield per pot (g pot−1) was significantly higher in treatment T3 than in treatments T2 and T1; and the yield was significantly higher in treatment T2 than in treatment T1. The N content on leaf, crown and root were significantly higher in treatments T2 and T3 than in treatment T1. During the late crop cycle, treatment with DMPP (T2 and T3) increased the contents of antioxidant compounds such as vitamin C (AsA) and phenolics. This may be due to the lower losses of antioxidants compounds, because NH4+ can be used directly for protein metabolism. Total increase in yield resulting from treatments including DMPP may be due, among other factors, to the increase of N content in leaves, crown and root of plants treated with DMPP; the lower loss of antioxidant compounds can be directly attributed to protein metabolism and the increase of SPAD values in treatments T2 and T3.