Evaluation crop indices of canola spring genotypes in terminal drought stress conditions and foliar application of Potassium silicate

Drought is a restriction in crop production in arid and semiarid regions. It is forecast that climate change may cause droughts shortly. After oxygen, silicon (Si) is the second most common element in the soil. In reducing both biotic stress (e.g., plant diseases and pest damage) and abiotic stresses such as salinity, drought, aluminum toxicity, heavy metal toxicity, nutrient imbalance, lodging, radiation, high temperature, wounding, and freezing.

In order to study the effects of terminal drought stress and foliar application of potassium silicate on yield and canola spring genotypes components, a factorial split-plot test was conducted in Karaj, Iran in a full randomized block configuration with three replications for two years of cultivation (2016-2018). The irrigation was performed at two levels in this study, including routine irrigation (control) and interruption of irrigation from the pod formation stage. Potassium silicate foliar application at two levels comprised of 0 and 4 g liter-1 in factorial status in main plots and five Brassica napus L. genotypes including OG × AL, RGS × SLM, DALGAN, RGS003 and RGS × Okapi in subplots. SAS Ver 9.1 statistical analysis was used for variance analysis.

Combined variance analysis showed that the impact of the year on some characteristics seed number in silique, silique length and seed yield was significant. Also, the effect of irrigation was significant on seed yield. The effect of genotype on plant height was significant indicating that the genotypes had different reactions. The interaction effect of irrigation × genotype on Harvest index was significant. The interaction effect of Irrigation × Potassium Silicate × Genotype on branch number, silique number, silique length, seed number in silique, seed weight, biological yield, seed yield, oil content and oil yield was significant. The mean comparison of irrigation and Potassium silicate interaction demonstrated that the most grain yield was observed in normal irrigation and the least value related to cut off irrigation at pod formation stage. The results indicated that, irrigation, foliar application of Potassium silicate and their interaction had significant effect on growth and agronomic traits and increased them.

Finally, our study showed the beneficial effects of Potassium Silicate in improving the drought tolerance of canola plants, especially at the end of the season. This can provide a basis for attempting new strategies to reduce the damage from drought and create a functional link between the role of silicon, physiological response and tolerance to drought stress in canola plants. According to the results, in the case of application of Potassium Silicate and normal irrigation, the promising genotype of OG×AL, with the highest seed and oil yield, is recommended as standard. Also, in the case of application of Potassium Silicate and late-season drought stress (restricted irrigation from the pod formation stages), RGS × SLM and DALGAN with the highest seed yield, is recommended.