Effects of potassium nitrate on growth and photosynthetic pigments of basil under Colletotrichum gloeosporioides infection

This study was conducted to investigate the effects of different concentrations of potassium nitrate (0, 4, 8 and 12 mM) on growth, dry weight and total chlorophyll and phenol of basil (Ocimum basilicum L.) under Colletotrichum gloeosporioides infection. The experiment was factorial based on a randomized complete block design with four replications. All growth characteristics, dry weight of shoots and roots and photosynthetic pigments of infected plants decreased. Application of potassium nitrate, especially at concentration of 12 mM, could increase the amount and activity of photosynthetic pigments and total phenol in basil which resulted, in reducing the negative effects of C. gloeosporioides infection and an increase on leaf area, dry weight of shoot as compared with those of control (non-application of potassium nitrate). Foliar applications of potassium nitrate not have significant effect on dry weight of roots and leaf number as compared with those of the control. Application of foliar mineral, KNO3 significantly increased nitrate content and nitrate reductase.