Effect of nano titanium dioxide on yield and yield components of safflower under normal and low irrigation

Introduction Plant oil is one of the basic human food needs. Due to the increasing population,increase the area under crop cultivation and enhance the performance of them is essential. Increase of oil yield is primarily associated with increase in seed yield. The importance of oil crops such as safflower has increased in recent years. Safflower has the special place in Iran because it shows high compatibility with the country's climate. Drought stress is one of the most important environmental stresses affecting agricultural productivity around the world and may result in considerable yield reductions. Safflower (Carthamus tinctorius L.) is a tap-rooted annual crop which can tolerate environmental stresses including salinity and water stress. In most plants, the time during flowering to seed developments are sensitive to water deficit. Nanoparticles can facilitate effective absorption of fertilizers at Nano scale. Furthermore nanoparticles can facilitate enhanced ability of water absorption by roots, and increase antioxidant enzyme activity such. Thus, nanoparticles can increase plant resistance against different stresses. Titanium dioxide nanoparticles are used in agriculture to increase growth and yield, improve the rate of photosynthesis and reduce disease. The application of TiO2 has been found to show excellent efficacy in wheat, soybean, Lentil and spinach  This study aimed to investigate the effect of foliar application of Nano Tio2 on yield and yield components of safflower genotypes under normal and low irrigation.   Materials and methods To study the effect of Tio2 Nano particles spraying on yield and yield components of safflower genotypes under normal and low irrigation conditions, a split factorial experiment was conducted in randomized complete block design with three replications in the research field of Imam Khomeini International University, Qazvin, in 2014. Irrigation regime includes regular watering (irrigation after 60 mm evaporation from class A evaporation pan) and low irrigation (watering until late flowering similar to normal irrigation and late flowering to maturity, irrigation after 100 mm evaporation from class A evaporation pan) were considered as the main factor. Tio2 in two levels, including the use of Tio2 (0.05 percent concentration before flowering) and non-use (control) and genotypes in eight levels including Kuseh Local, Sina, Isfahan Local, Mexican 88, Faraman, Soffe, Goldasht, Mexican 11 were considered as sub-factors. In this experiment traits number of heads per plant, number of seed per head, head diameter, 1000 grain weight, harvest index and grain yield were studied.   Results and discussion The irrigation effect was significant for traits 1000 grain weight, harvest index and grain yield. Low irrigation stress reduced the number of heads, head diameter, 1000 grain weight, harvest index, and grain yield. In other experiment water stress caused plant height, number of heads and grain yield decreasing in safflower.  The effect of Tio2 utilization was significant on head diameter, harvest index and grain yield. Tio2 increased head diameter, harvest index and grain yield as well as significantly reduced the adverse effect of low irrigation stress on head diameter. The other research results on effects of different Nano titanium dioxide concentrations (0.01, 0.02, and 0.03 percent) and titanium dioxide (bulk) spray treatment on barley plants showed that traits of grain yield, number of ears and harvest index in all treatments of Nano titanium dioxide application were more effective than the control treatment. The Irrigation and Nano Tio2 interaction effect was significant for grain yield. Nano Tio2 particles increased grain yield only in normal irrigation. Nano-titanium dioxide is likely to increase grain yield through improving light absorption and increasing the efficiency of photosynthesis. Genotype differences for all traits except head diameter were significant. Although the highest grain yield was obtained from Faraman, Sina and Isfahan Local were not significantly different from Faraman. The lowest grain yield was belonged to Mexican 11 and Mexican 88.   Conclusions The results demonstrated that low irrigation stress caused significant reduction in 1000 grain weight, harvest index and grain yield. The seed weight is an important component of yield and due to decreasing in seed weight grain yield decreased. The adverse effect of stress on head number, reduced by application of Tio2 although, Tio2 effect was not significant for other traits in stress condition. The plant growth stage and concentration of Tio2 are also important and they are different for different plants or even for different characteristics. Generally, Faraman, Sina, Isfahan Local had the highest performance in Qazvin climate.