Effect of drought stress on oil content and fatty acids composition of some safflower genotypes | Yousef Joshan, Behzad Sani<a target=

Two field experiments were carried out during 2018–2019 at the Hamedan and Qom sites, which are different ecological locations of Iran. Hamedan was selected as a temperate climate and Qom as semi-arid to study some of the morphological and physiological traits of fodder beet in various climatic conditions. The experimental map was designed as a split–split-plot in the form of a randomized complete block with three replications. The main plots were assigned three levels of methanol (i.e., control, 15, and 30% by volume). The sub-plots were restricted to two glycine betaine (GB) concentrations (i.e., control and four grams per liter of methanol consumed, and the sub-sub-plots consisted of six different genotypes of fodder beet). The results showed that root length, root and foliage yield/ha, as well as sugar content increased with the incremental level of methanol and/or GB concentration. Foliar application of methanol and GB also significantly changed the qualitative parameters including sodium content, catalase value, crude protein percentage, and dry matter digestibility. It should be noted that two sites differed in most of the investigated traits, so that Hamedan treatment had a more active role on fodder beet growth, yield, and quality compared with Qom. Meanwhile, there was a significant difference between fodder beet genotypes. Generally, spraying fodder beet with 15%by volume methanol or GB with concentration of four grams per liter of methanol is the recommended treatment for raising forage yield under the ecological circumstances of this research.

The sowing date is an important factor for expanding the cultivated area of rapeseed and affects seed yield, oil content, and fatty acid compounds. Micronutrient elements play an important role in improving the vegetative and reproductive growth of the plant, especially under conditions of biological and environmental stresses. A two-year experiment (2014-2016) was performed to study the response of rapeseed genotypes to foliar application of micronutrients on different sowing dates. The treatments were arranged as a factorial-split plot in a randomized complete block design with three replicates. Three sowing dates of 7 (well-timed sowing date), 17, and 27 (delayed sowing dates) October and two levels of foliar application with pure water (control), selenium (1.5%), zinc (1.5%), and selenium+zinc (1.5%) were factorial in the main plots and five genotypes of SW102, Ahmadi, GKH2624, GK-Gabriella, and Okapi were randomized in the subplots (a total of 30 treatments). Seed yield, oil yield and content, oleic acid, and linoleic acid were reduced when rapeseeds were cultivated on 17 and 27 October, while the contents in palmitic, linolenic, and erucic acids, and glucosinolate increased (p < 0.01). a selenium+zinc treatment improved seed yield, oil content and yield (p < 0.01). The oil quality increased due to increased contents of oleic and linoleic acids under the selenium+zinc treatment (p < 0.01). The GK-Gabriella and GKH2624 genotypes are recommended to be sown on well-timed (7 October) and delayed sowing dates (17 and 27 October) and treated with selenium+zinc due to the higher oil yield, linoleic and oleic acids.

In this experiment, we investigated the effects of drought combined with exogenous silicon (Si) and potassium application on super sweet corn growth and development. Drought stress caused decreases in the stem diameter, leaf area, cob length, ...

Identification of drought-tolerant, high-yielding rapeseed (Brassica napus L.) genotypes is critical for cultivation in semiarid regions, where water scarcity severely limits agricultural productivity. In this study, 38 winter rapeseed genotypes were evaluated using a randomized complete block design (RCBD) with three replications under two different environments (normal and drought stress). Drought tolerance was assessed based on multiple yield-related indices, while multivariate analyses, including PCA-biplot, GT-biplot, and cluster analysis (WARD method), were employed to dissect genotype performance. Additionally, fatty acid profiles were analysed to explore the impact of drought stress on seed oil composition. Significant differences among genotypes for seed yield were observed (P ≤ 0.05). Genotype G13 exhibited the highest yield (5.92 t ha⁻¹) under normal irrigation, while G10 achieved the highest yield (4.2 t ha⁻¹) under drought stress. Consistently, G10 also showed the highest values of STI (0.984), GMP (4.478), and YI (1.292), along with the lowest SSI (0.425) and YR (11.93%), confirming its drought tolerance. PCA-biplot analysis identified G33, G23, G18, G6, and G10 as the most stable and drought-tolerant genotypes. Cluster analysis supported these results, grouping the superior genotypes into the third cluster characterized by high STI, RDI, K2STI, and YSI values, and low TOL, SSI, and YR values. GT-biplot indicated strong correlations between YS and indices such as RDI, YSI, YI, and K2STI, while YP correlated with K1STI, TOL, SSI, and YR, distinguishing drought-susceptible high-yielding genotypes. Polygon view analysis highlighted G10 as the most superior genotype across drought indices. In terms of fatty acid composition, drought stress increased palmitic, linoleic, linolenic, erucic, and polyunsaturated fatty acids, while reducing stearic, oleic, saturated, and monounsaturated fatty acids. Notably, genotype G10 showed relatively smaller changes in its fatty acid composition under drought stress compared to other evaluated genotypes. This study identified several rapeseed genotypes with varying drought tolerance and yield performance, with G10 and G13 emerging as the most promising under drought and normal conditions, respectively. The identified genotypes offer promising genetic resources for breeding programs aiming to improve rapeseed adaptation to water-limited environments.