The effect of different nitrogen forms on tomato spotted wilt virus infection and plant growth parameters of pepper plants grown in water deficient conditions

Plant nutrients has an impact on tolerance of plants against abiotic and biotic stress conditions. Water deficiency, which is one of abiotic stress factors, is important both in plant and plant-pathogen interactions. In this study, the effects of different nitrogen forms given at the same doses on Tomato spotted wilt virus (TSWV) infection and plant growth parameters of pepper cultivar "Kandil Dolma" grown in perlit: peat (1:4) mixture under limited (30%) and full (70%) irrigation conditions. In this study, five different plant nutrients [NH4NO3, NH4(SO4)2, Mg(NO3)2, Mg(SO4)2 ve Üre] with three replications were applied to pepper plants grown under two irrigation conditions, and the plants were mechanically inoculated with TSWV after two weeks of nutrient treatment. All plants (TSWV-inoculated and non-inoculated) were tested by enzyme linked immunosorbent assay (ELISA) to confirm virus infection four and eight weeks after mechanical inoculation. The mean absorbance values of control plants (virus-inoculated non-fertilized) grown under limited and full irrigation indicated that these plants have higher virus titre. When compared, the pepper plants applied with urea and nitrate-containing fertilizers [NH4NO3, Mg(NO3)2] had more tolerance to TSWV under water limited condition, whereas the plants applied with sulphate-containing fertilizers (NH4SO4 and MgSO4) were relatively affected by the virus more than other treatments. Also, the severity of TSWV symptoms decreased in infected-pepper plants (except the ones treated with sulphate-containing nutrients) grown under limited irrigation. In water deficient condition, total evapotranspiration (ET) values of healthy and infected plants decreased significantly when compared with those of fully irrigated ones, however, this reduction was more obvious in plants treated with NH4SO4 and MgSO4. The results of the study showed that biomass loss of infected plants was higher in full-irrigated plants (23%) than limited-irrigated ones (12%). All nutrient-applied healthy plants, except MgSO4-treated ones, had higher mean water use efficiency (WUE) under full irrigation, while urea and NH4NO3-applied infected plants had higher WUE than the others under limited irrigation. This study indicated that TSWV infection and urea, NH4NO3 or Mg(NO3)2 interactions may provide positive contribution on plant fitness or some nutrients may supress virus infection under water deficient conditions. In future, the impact of nutrients and their concentrations on plant-virus interactions under different water stress in field conditions are needed to be studied.