Effect of humic acid on the yield and some morphological characteristic of safflower (Carthamus tinctorius L.) under drought stress conditions

In order to evaluate the effect of drought stress on the some morphological characteristics, grain yield and oil yield of safflower, an experiment conducted as split plot arrangement based on RCBD design with three replications at the Research Station of Shahrekord University. Main factor include four levels of drought stress (irrigation after 50, 80, 130, and 180 mm evaporation from evaporation pan of class A) and sub factor include four levels of humic acid (0, 1, 3, and 6 lit/ha) were considered. some Agronomic characteristics such as plant height, sub branch per plant, stem diameter, leaf number per plant, grain yield and oil yield were evaluated. Drought stress and foliar application of humic acid contributed the above mentioned traits. Based on the mean comparison test, drought stress significantly decreased and foliar application of humic acid increased the traits of include plant height, sub branch per plant, stem diameter, leaf number per plant, grain yield and oil yield. The highest grain and oil yields were 1687 and 393.7 kg / ha respectively in irrigation after 50 mm evaporation. Maximum amount of humic acid solution was 6 liters per hectare, which increased grain yield (9%) and oil yield (20%) than control treatment. Based on the results of this experiment and due to the positive effects of humic acid sprayed on safflower plants, recommended in case of risk of drought stress during the growing season of plants, the positive characteristics of organic matter to increase the vegetative and reproductive growth of safflower given more attention.