Does Potassium Silicate Improve Physiological and Agronomic Traits and Oil Compositions of Rapeseed Genotypes Under Well-Watered and Water-Limited Conditions?

Descurainia sophia has potential use as an oil crop because of its high productivity, high seed oil content, and unique fatty acid composition. With regard to oil fatty acid composition, obtainable oil from this plant can be of interest to the food and non-food industries such as pharmaceuticals, cosmetics, bio-fuels, paints, and lubricants. The aim of this research was to determine the effects of various nitrogen (N) rates and different irrigation regimes on oil productivity and composition as well as on potassium (K) and phosphorus (P) parameters in D. sophia. The field experiment was arranged as split-plot in a randomized complete block design with three replications. The main plots were three irrigation regimes: 0.1 maximum allowable depletion or deficiency (MAD) of available soil water (ASW) (I1), 0.2 MAD of ASW (I2), and 0.4 MAD of ASW (I4) in 2010 and 0.2 MAD of ASW (I2), 0.4 MAD of ASW (I4), and 0.8 MAD of ASW (I8) in 2011. Sub-plots were three N rates: 0 (N0), 200 (N200), and 300 (N300) kg N ha−1. In the first year, there was no significant difference between irrigation regimes in terms of oil yield, while oil yield decreased when plants were exposed to drought stress in comparison with the well-water condition in the second year. The application of N increased oil yield; although there were no significant differences between N200 and N300 under any irrigation regime, the highest oil yield being observed at N application rate of 200 kg ha−1 for the I1 (561.4 kg ha−1) and I2 (256.1 kg ha−1) regimes in 2010 and 2011, respectively. Accumulation (per ha) of 21.9–29.7 kg P (50–68 kg P2O5) and 102.1–126.3 kg K (123–152 kg K2O) was required to produce 256.1–561.4 kg ha−1 of oil yield. Overall, for most of the traits studied over the 2 years, the response of D. sophia was mainly due to N rate rather than irrigation treatment. Linolenic, linoleic, and oleic acids comprised about 70% of the fatty acid composition. The results obtained here suggest that D. sophia oil yield, P and K uptakes, and levels of saturated and polyunsaturated fatty acids are positively influenced by increasing available N under different irrigation regimes.

Effects of Nitrogen and Water on Nutrient Uptake, Oil Productivity, and Composition of Descurainia sophia

Foliar Application of Humic Acids Improves Seed Yield and Oil Quality of Rapeseed (Brassica napus L.) Genotypes at Well-Time and Late Planting Dates

Influence of Sowing Dates and Genotypes on Phenology, Morphology, Yield and Fatty Acid Compounds of Sinapis alba L. for the Energy Industry

To determine the suitable sowing date in each region, it is important to note that environmental conditions should be optimal during the crop growing season. Plant nutrition using macro-elements and micro-elements improves crop growth and quantitative and qualitative yields under environmental stresses. A 2-year experiment (2015–2016 and 2016–2017) was conducted to investigate the effect of zinc (Zn) foliar spray on quantitative and qualitative yields of spring rapeseed genotypes at winter sowing dates. The factorial split-plot arrangement of treatments was set up in a randomized complete block design with three replications. Main plots included three winter sowing dates of 9, 19, and 29 February and Zn foliar spray at two levels of non-Zn foliar spray (control) and Zn foliar spray (5 g l−1 at the stem elongation stage). Sub-plots contained four genotypes of Sarigol, Dalgan, Salsa, and Solar. While silique number per plant, seed number per silique, 1000-seed weight, seed yield, oil yield and content, and oleic, linoleic, and palmitic acids of the study genotypes were lessened at late sowing dates, contents of linolenic, stearic, and erucic acids and glucosinolate were significantly increased in such condition. Zn foliar spray improved seed yield and yield components, oil yield and content, and linoleic acid content, while contents of linolenic, stearic, and erucic acids and glucosinolate were dropped. Overall, the current study suggests that to produce the optimal quantitative and qualitative yields in rapeseed agro-ecosystems, genotypes should be cultivated on an optimum winter sowing date (February 9) and treated with Zn.

Zn Foliar Spray as a Management Strategy Boosts Oil Qualitative and Quantitative Traits of Spring Rapeseed Genotypes at Winter Sowing Dates

A factorial split-plot experiment (2015–17) was carried out in a randomized complete block design with three replications at Karaj, Iran, to investigate the quantitative and qualitative responses of rapeseed genotypes to the exogenous application of salicylic acid at various plant densities. Three plant densities (40, 50, and 60 plants m−2) and two levels of application of salicylic acid (non-application and foliar application) were factorial in the main plots and six rapeseed genotypes (HW118, WPN6, HL3721, L14, Tassilo, and Natali) were in sub-plots. The number of siliques per plant, number of seeds per silique, seed yield, and oil yield improved when rapeseed genotypes treated with salicylic acid. The oil quality of studied genotypes enhanced due to a reduction in erucic acid and glucosinolate contents under the foliar application of salicylic acid. On average, by foliar application of salicylic acid, the highest seed and oil yields at the density of 40 plants m−2 belonged to the L14 genotype, while the HW118 produced the maximum seed and oil yields at the densities of 50 and 60 plants m−2. Generally, rapeseed genotypes should be cultivated at the density of 40 plant m−2 and treated with foliar application of salicylic acid for achieving the maximum seed yield and oil quality.

Farnaz Ganj-Abadi

Papers

Zn Foliar Spray as a Management Strategy Boosts Oil Qualitative and Quantitative Traits of Spring Rapeseed Genotypes at Winter Sowing Dates

Grain Yield and Qualitative of Rapeseed Genotypes Change in Response to Exogenous Application of Salicylic Acid and Planting Density