Investigating of kaolin in increasing of drought tolerance of Basil (Ocimum basilicum var. purpurascens)

Introduction Drought stress is one of the important adverse factors that limits plant growth and productivity. Drought stress induces a range of physiological and biochemical responses in plants. Plants also respond and adapt to water deficit at both cellular and molecular levels, for instance through accumulation of osmolytes and proteins specifically involved in stress tolerance. Plants’ responses to water stress are also species and cultivar-dependent characteristics. Foliar application of kaolin has been evaluated for its ability to reduce the negative effects of water stress and to improve the physiology and productivity of Plants. The purpose of this research is to determine the effects of different kaolin concentrations, on the physiological and morphological characteristics of purple basil under deficit irrigation conditions. Materials and methods In order to investigate of Kaolin on increasing of drought tolerance of Basil, a factorial experiment was conducted based on randomized complete block design with 3 replications in researcher greenhouses of Yazd university during 2017-18 growing season. The treatments were four levels of deficit irrigation including: I1=25%FC, I2=50%FC, I3=75%FC, I4=100%FC field capacity and three levels of kaolin concentrations consisted of K1=0%, K2=3%, K3=6%. In a factorial experiment based on completely randomized design with three replications. After the plants establishment, drought treatments were imposed. After 40 days of applying drought treatments, kaolin was twice sprayed with 7 days interval. The leaves of plants were sampled one week after the last spraying and transferred to the laboratory and the amount of soluble sugars, proline and chlorophyll concentrations were measured. In order to analysis data, analysis two-way ANOVA were used and FLST test compared means after normality test. Statistical analysis was performed using SAS software, and Excel software was used for drawing the charts. Results and discussion The results showed that the effect of kaolin foliar application and moisture stress was significant on plant height, plant diameter, leaf area, shoot dry weight, root dry weight, root volume, RWC, chlorophyll a, chlorophyll b, total chlorophyll, proline and soluble sugar (p