Dahlia variabilis L. is a valued tuberous ornamental crop grown worldwide for its attractive flowers. Optimizing nutrient management is crucial for maximizing dahlia growth and tuber yield. In this field study, we evaluated the combined effects of humic acid (HA) and chemical fertilizers on the tuber production of Dahlia variabilis L. A factorial randomized complete block design was used with treatments combining three fertilizer levels (100%, 75%, and 50% of recommended NPK dose) and multiple HA treatments. HA was applied as a soil amendment and foliar spray in combination with inorganic NPK fertilizer. Results showed that integrating HA with reduced fertilizer doses enhanced plant growth and tuber yield. The treatment combining 75% of the recommended NPK dose (75–90 75 kg ha–1 NPK) with HA produced significantly greater tuber yield than the full dose of NPK (control). Thus, HA application synergizes with NPK fertilization to amplify dahlia tuber yield, suggesting that sustainable integrated nutrient management can maintain high yield while reducing chemical fertilizer inputs.
Wheat is a primary source of sustenance for around 2 billion people worldwide; however, its production is threatened by the water scarcity associated with climate change. In the search for climate-smart wheat varieties, atmospheric moisture in the form of fog and dew is gaining attention as a sustainable, self-irrigating water source for crops. Leaf rolling (LR) is a well-known adaptive trait under water deficit conditions that supports fog moisture capture in wheat; however, little is known about its genetic potential and inheritance pattern, particularly given its high environmental influence. This study assesses the genetic heritability, combining ability, and diversity of LR among diverse wheat genotypes. Fifteen wheat genotypes identified in a previous research were evaluated for LR, soil moisture difference (MD), and cumulative drought stress responsive index (CDSRI), and fog-capturing and noncapturing genotypes were compared. Among the analyzed genotypes, F2-109 and A-46, exhibiting twisted type LR, were identified with 2% MD and >10 CDSRI values. Subsequently, the effects of static contact angle (SCA) and leaf runoff were assessed for five drought-tolerant and fog-capturing types and three drought-susceptible types. It was found that genotypes with low SCA (70–100°), and high MD (>2%) and leaf runoff (2 mL) captured more water within the root zone, attributed to the twisted-type LR. These five lines and three testers were hybridized following a line × tester mating approach, and heritability, combination ability, and other genetic parameters were computed. The lines accounted for 63% of the total variance in LR, 50% in water use efficiency, and 53% in grain yield. The high narrow sense heritability (18.5%) estimates for LR and physiological traits were indicative of additive gene action, supporting their selection for improvement. This identification of leaf traits that contribute to water use efficiency supports the development of climate-smart wheat varieties for arid and semiarid regions.
One of the most significant problems facing different ecosystems worldwide is the pollution of soil and water resources with heavy metals, which are harmful to biota. Metals are absorbed by plant roots through soil-plant interaction, leading to accumulation in plants. The plant's growth phase is one of the most important factors in heavy metal uptake and accumulation. Among heavy metal elements, nickel is one of the serious environmental pollutants and plant growth inhibitors due to its toxicity and persistent nature at high concentrations, as well as its bioaccumulation in ecosystems. This study aims to investigate how nickel accumulation in plant organs (roots, stems and leaves) and morphological characteristics (plant height, stem thickness, dry weights of roots, stems and leaves and root length) of silage maize seedlings at different growth stages (0, 5, 10, 15 and 20 days) change when exposed to different nickel (Ni) concentrations (0, 100, 200, 300, 400, 500, and 600 mg kg-1). Results showed that the highest Ni accumulation was obtained in the 20-day-old seedlings, while the lowest value was observed in the 10-day-old seedlings. The highest plant height, stem thickness, dry leaf weight, and dry stem weight were mostly observed in 5-day-old seedlings. In the study, the treatment of 500 and 600 mg kg-1 Ni to the plants resulted in plant death, while the treatment of 200 mg kg-1 Ni led to improvements in morphological characteristics. In terms of animal feed, 10-day-old seedlings are considered more advantageous because they contain less Ni compared to those grown from seed and other age groups, whereas 20-day-old seedlings are not recommended due to both their high Ni accumulation and weaker morphological characteristics. Considering the remediation capacity, we can say that 20-day-old seedlings may have the potential to be evaluated in areas contaminated with 300 and 400 mg kg-1 Ni.
Desert wheat grass (Agropyron desertorum Fisch. ex Link) is a valuable species in the temperate zones that exhibits tolerance to cold and drought and naturally grows in arid and semiarid regions of Iran. This research was conducted to investigate the phenotypic diversity of 50 selected genotypes of Iranian A. desertorum based on several agromorphological traits and forage production. Genotypes were planted in a randomized complete block design with four replications in 2016. The results showed highly significant differences among genotypes for all traits (p < 0.01). Broad-sense heritability estimates ranged from low to medium for the evaluated traits. The highest heritability values were observed for crown diameter, plant height (PH) and dry matter yield (DMY), while the genetic advance (GA) values were found for forage fresh weight and DMY. Selection based on traits with high GA and heritability is expected to be effective, indicating sufficient genetic variation for breeding programs. The number of stems (NS) and PH explained more than 73% of the entire variation in DMY in the stepwise multiple linear regression analysis. Principal coordinate analysis (PCoA) revealed that the first three coordinates (PCo1–PCo3) explained 82.4% of the phenotypic variation. According to the PCoA plot based on these coordinates, the genotypes were grouped into two groups. In the factor analysis (FA), factor 1 (FAC1) had a positive relationship with forage yield and NS; therefore, it was identified as a biomass factor. Cluster analysis divided the genotypes into two groups: cluster 1 contained 19 genotypes, and cluster 2 consisted of 31 genotypes. Significant phenotypic diversity was detected among the A. desertorum genotypes, indicating a valuable germplasm to employ in forage varietal improvement programs. Furthermore, the examined genotypes can serve as valuable germplasm for development of a core collection of A. desertorum in Iran.
Anthropogenic pressures on freshwater ecosystems have increased metal contamination in riparian zones; however, biological thresholds that distinguish tolerable exposure from ecologically significant accumulation remain poorly defined. This study investigated species-specific thresholds for heavy metal uptake in riparian macrophytes to establish a biologically grounded framework for ecological risk assessment in impacted streams. A gradient encompassing five sites was used to sample four dominant macrophyte species: Typha latifolia, Phragmites australis, Lythrum salicaria, and Persicaria lapathifolia. Concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) in aboveground plant biomass were examined in relation to their corresponding concentrations in stream water using piecewise regression to identify threshold points (τ). These thresholds mark significant changes in the relationship between environmental metal availability and metal accumulation in aboveground biomass, indicating a shift in uptake dynamics. Identified threshold values ranged from 2.05 to 5.99 µg L⁻¹ (Cd), 1.91–70.5 µg L⁻¹ (Cr), 0.05–42.3 µg L⁻¹ (Cu), 75.2–555 µg L⁻¹ (Fe), 0.05–24.2 µg L⁻¹ (Ni), 0.29–30.9 µg L⁻¹ (Pb), and 1.55–244 µg L⁻¹ (Zn), with regression models explaining up to 81% of the observed variation in uptake. Thresholds were highly species-specific. For instance, the sensitive species Persicaria lapathifolia exceeded its calculated thresholds in 75–100% of observations. In contrast, the generally tolerant Typha latifolia showed an early threshold response specifically for Cu. Phragmites australis responded primarily under high exposure, except for Zn, for which its threshold was notably low. By integrating species-specific threshold determination with exceedance frequency analysis, this study provides a practical framework to distinguish zones requiring early biological warning from those subject to long-term accumulation. Furthermore, by establishing the first species-specific thresholds for macrophyte metal uptake in Türkiye, this study provides a scientifically grounded tool for selecting appropriate plant species for phytoremediation and watershed restoration initiatives.
