Influence of nitrification inhibitor DMPP on yield, fruit quality and SPAD values of strawberry plants

3,4-Dimethylpyrazole phosphate (DMPP) is a nitrification inhibitor with highly favourable properties. It has undergone thorough toxicology and ecotoxicology tests and experiments of technological application, and has been shown to have several distinct advantages compared to the nitrification inhibitors currently used. DMPP is very efficient in inhibiting soil nitrification and increasing N fertilizer efficiency, crop yield and fruit quality, and DMPP has no toxicological effects. There have been a few investigations about the phytotoxic damage and the influence of nitrification inhibitor DMPP on yield and fruit quality in strawberry plants. The aim of this research was to evaluate the effect of DMPP on yield, fruit quality and SPAD values in the young leaves of strawberry plants in the soil growing system. The experiment was carried out in Huelva (Spain) in a greenhouse from October 2012 to June 2013 on one strawberry (Fragaria×ananassa Duch.) cultivar: ‘Candonga’. A completely randomized block design with 4 treatments and 3 replications was established. The sample number per treatment were 30 plants (10 plants per replication), then we used total 120 plants. The treatments were—T1: 100% NOVATEC® Solub 21 (21% N–NH4+, 0.8% DMPP, 60% SO3); T2: 75% NOVATEC® Solub 21 (21% N–NH4+, 0.8% DMPP, 60% SO3)+25% ammonium nitrate 34% N–(NH4NO3); T3: 25% NOVATEC® Solub 21 (21% N–NH4+, 0.8% DMPP, 60% SO3)+75% ammonium nitrate 34% N–(NH4NO3); and T4: 100% ammonium nitrate 34% N–(NH4NO3). During the early crop cycle, an increase in fruit size was observed in treatment with DMPP. There is some beneficial effect of treatment with DMPP on increasing SPAD in the ‘Candonga’ cultivar. During the late crop cycle, the effect of treatment and week since planting on Ascorbic acid was significant and the highest value was recorded in treatment T1. In conclusion, the AsA rise resulting from treatment with DMPP might be due to the increase in fruit size resulting from treatment with DMPP and it seems there is some beneficial effect of treatment with DMPP on increasing SPAD. Therefore, the fruit size increase resulting from treatment with DMPP during the early crop cycle might be due to the rise in SPAD values.