Study the effect of drought stress and iron oxide nanoparticle foliar application on quantitative and qualitative traits of sesame (Sesamum indicum L.)

Sesame (Sesamum indicum L.) is one of the oldest oil seed crops, growing widely in tropical and subtropical areas. Drought is a polygenic stress and is considered as one of the most important factors limiting crop yields around the world. Most of the Iranian soils have a high pH and calcareous nature, and micronutrients solubility in these soils is low. Micronutrient deficiency, especially iron, is widespread where soil is calcareous with high pH, low organic matter, continuous drought, high bicarbonate content in irrigation water, and imbalanced application of NPK fertilizers. Foliar nutrition is an option when nutrient deficiencies cannot be corrected by applications of nutrients to the soil. Microelements Foliar application is very helpful when the roots cannot provide necessary nutrients. Iron is an important element in crops, because it is essential for many enzymes including cytochromes, which is involved in the electron transport chain, chlorophyll synthesis, and maintains the structure of chloroplasts. Nowadays, nanoparticles of metals are widely used in many sections, such as medicine, agriculture, and industry. Iron oxide nanoparticles have a large surface area and high reactivity. Moreover, when compared to many other metallic nanoparticles, the iron oxide nanoparticles are constant, less expensive, and less toxic. Iron oxide nanoparticles have high magnetization amounts, a size smaller than 100 nm and a thin particle size distribution. These particles also have a special surface cover of magnetic particles, which has to be harmless and biocompatible.

To study the effect of drought stress and iron oxide nanoparticle foliar application on quantitative and qualitative traits of sesame (Sesamum indicum L.), an experiment was conducted as split-plot with three replications at the research farm of Agricultural Faculty, Lorestan University in 2016. The experimental factors were included drought stress in two levels of non-stress (Irrigation to reach soil water to FC 100%) and drought stress (Irrigation to reach soil water to FC 50%) as the main factor, and iron oxide nanoparticle foliar application in five levels of non-foliar application (Control), foliar application by water (1000 liters of water per hectare), iron oxide nanoparticle 0.05% (0.5 kg/1000 L of water per hectare), iron oxide nanoparticle 0.1% (1.0 kg/1000 L of water per hectare) and iron oxide nanoparticle 0.15% (1.5 kg/1000 L of water per hectare) as the sub factor. The measured traits included number of capsules per plant, 1000 grain weight, grain yield, biological yield, harvest index, grain oil content, grain oil yield, grain protein content and grain protein yield. Analysis of variance was performed using general linear model (GLM) procedure of statistical analysis system (SAS version: 9.3). The means were analyzed using the Tukey test at P=0.05.

Results showed that the drought stress decreased significantly traits of 1000 grain weight (18.51%), grain yield (26.52%), biological yield (9.42%), harvest index (3.94%), grain oil content (10.30%), grain oil yield (40.47%) and grain protein yield (24.90%) except for the number of capsules per plant and grain protein content. However, the iron oxide nanoparticle application improved significantly traits of 1000 grain weight (19.86%), grain yield (37.43%), biological yield (22.91%), harvest index (3.86%), grain oil content (6.49%), grain oil yield (45.70%) and grain protein yield (40.93%) under drought stress except for the number of capsules per plant, and grain protein content. Among different levels of foliar application, iron oxide nanoparticle 0.15% had the most effect on increasing the measured traits except for the harvest index.

In general, iron oxide nanoparticle foliar application can be used, especially at a concentration of 0.15%, to reduce the harmful effects of drought stress and improve the quantitative and qualitative traits of sesame in Khorramabad city.