Abstract
Safflower is one of important crop in semi-arid regions of the world, where the precipitations are limited. In order to investigate the effect of foliar spray of nano-silicon dioxide (10 and 20 mM) and nano titanium dioxide (25 and 50 mM) and water-deficit stress (irrigation after 110 mm evaporation) on growth parameters and yield components of spring safflower a field experiment was carried out at the highland semi-arid region, in, North West of Iran. Water deficit stress significantly reduced morpho-physiological traits such as ground cover, canopy width, leaf fresh mass, leaf are and plant height) as well as yield components (e.g. capitulum diameter, seed mass and seed number per capitulum). However, the plants grown under water deficit condition showed the higher harvest index than well irrigated plants. Comparison of the foliar treatments showed that the both nano-particles (silicon and titanium) improved the plant growth and yield components over the control. However, the effect of nano-silicon was more prominent than titanium. The highest amount of seed oil was recorded under well irrigated condition (irrigation after 60 mm evaporation) with foliar application of nano-titanium. The percentage of palmitic acid, arachidic acid and myristic acid in seed increased by nano-titanium application. Altogether, principal component analysis indicated that spray of 10 mM nano silicon dioxide was best foliar treatments under all moisture regimes.
Highlights
The world's population is growing rapidly, so that by 2050, it is predicted to reach 9.1 billion, 34 %more than today (UN, 2013)
Results of analysis of variance (ANOVA) showed that, most of the morphophysiological traits were significantly affected by moisture regimes and foliar treatments (Table 1)
Assessments of ground cover between different combined treatments revealed that, the highest values were recorded for the plants grown under well irrigated condition and those subjected to foliar application with 25 mM Ti, 10 mM Si and 50 mM Ti, respectively (Figure 2)
Summary
The world's population is growing rapidly, so that by 2050, it is predicted to reach 9.1 billion, 34 %more than today (UN, 2013). Majority of this population growth is expected to occur in developing countries. These trends refer to the imperative note that, the food security is (and will increasingly continue to be) faced with a major challenge, necessitating anincrease in food production in these areas. In terms of climate, most of developing countries are located in semi-arid areas which are characterized by highly variable and unpredictable rainfall and total precipitations below potential evapotranspiration, making them frequently engaged with drought stress. Even at mild intensity, drought stress can inhibit photosynthesis and stomatal conductance significantly, resulting in considerable yield reductions (Shahrokhnia & Sepaskhah, 2017)
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