The effect of foliar application of kaolin, phosphorus and potassium on photosynthesis of pistachio trees cv. “Kalle-Ghouchiˮ

In an orchard experiment, the effects of foliar application of kaolin, potassium, phosphorus and their different combinations were examined on photosynthesis parameter 8-years-old pistachio trees cv.Kalle-ghouchi in 2016. There were ten treatments, including two rate of P (1 and 2%), two rates of K (1.5 and 3%), kaolin 5%, kaolin 5%+ P 1%, kaolin 5%+P 2%, kaolin 5%+ K 1.5%, kaolin 5%+ K 3% and control (use of distilled water). Foliar application of above treatment were performed in mid Jane when embryo growth is started (the maximum demand for photoassimilates). Photosynthetic parameters (photosynthesis and transpiration rate, stomatal conductance and sub stomatal CO2 concentration), chlorophyll fluorescence parameters (Fv/Fm and PI), photosynthetic pigments (chlorophyll a, b and total and total carotenoids) were measured in 5 stages (the first stage was one day after treatment and the others  were performed with one week interval). The results showed that non of treatments could improve photosynthesis parameters expect Ci while chlorophyll fluorescence parameters were improved by kaolin treatments and photosynthetic pigments were increased by most of experimental treatments. The result also showed that photosynthesis and transpiration rate and stomatal conductance were increased with time and sub-stomatal C02 concentration was decreased. Chlorophyll fluorescence indices and photosynthetic pigments were also increased with time. Totally, the effect of experimental treatments on photosynthetic parameters was under our expectation.