Investigating the effect of nanoselenium in improving the physiological, biochemical and agronomic characteristics of spring rapeseed under water deficit stress at the end of the season

Water deficit stress is one of the most common abiotic stresses that reduce the growth and yield of crops such as oilseed rape. The utilization of micronutrients in oilseed crops is one of the most useful and effective approach for improving the grain yield and plant adaptation under drought stress conditions. Accordingly, the aim of this study was to investigate the effect of foliar application of selenium nanoparticles on physiological, biochemical and agronomic characteristics of oilseed rape under the end season drought stress.

To investigate the effect of selenium nanoparticles on on some physiological, biochemical and agricultural characteristics of oilseed rape under the end season drought stress, a split-plot experiment was conducted in a randomized complete block design (RCBD) with three replications at research farm station of University of Mohaghegh Ardabili in 2017-2018. The treatments were irrigation (normal irrigation and omitting irrigation at the flowering stage) as main plots and selenium nanoparticles foliar application ((0 (control), 25 and 50 mg/l) as sub-plots. The cultivar studied was Hayola 401. The measured traits included Chlorophyll a, Chlorophyll b, Total Chlorophyll, Carotenoid, F0, Fm, Fv, Fv/Fm, relative water content, ion leakage, malondialdehyde, Catalase and grain yield. Analysis of variance and comparison of their means using by LSD test were done by the SAS software (version 9).

According to the results, drought stress significantly reduced the amount of photosynthetic pigment, relative water content and grain yield while amount malondialdehyde, ion leakage and chlorophyll fluorescence increased under drought stress conditions. Foliar spraying of nanoselenium with a concentration of 50 mg/liter increased catalase enzyme activity (82%), relative leaf water content (29 %), total chlorophyll (64 %) and decreased electrical conductivity of materials leaked from leaves by 23% could reduce the negative effects of drought stress. so that the grain yield increased (45%) by spraying 50 mg/l selenium nanoparticles in under drought stress conditions. The most positive and significantc orrelations were observed between grain yield and chlorophyll a, total chlorophyll (96** %).

The results of this study indicated that the using of molybdenum oxide nanoparticles under favorable irrigation conditions and drought stress could improve photosynthetic indices and biochemical traits. Foliar application of selenium nanoparticles, especially at 50 mg/l concentration, reduced the effects of drought stress by increasing the synthesis of chlorophyll and improving the process of photosynthesis and improved physiological and biochemical indices, thus improving the grain yield in favorable and unfavorable environmental conditions.