Potassium fertilization improves growth, yield and seed quality of sunflower (Helianthus annuus L.) under drought stress at different growth stages.

Water scarcity is a major concern for sunflower production in the semi-arid and arid regions of the world. Potassium (K) application has been found effective to alleviate the influence of drought stress; however, the impact of drought stress on seed quality of sunflower has not been reported frequently. Therefore, a field experiment was performed to determine the optimum K requirement for mitigating the adverse effects of water stress and improving growth and seed quality of spring-planted sunflower. Sunflower plants were exposed to water stress at different growth stages, i.e., Io = no stress (normal irrigation), I1 = pre-anthesisi stress (irrigation skipped at pre-anthesis stage), I2 = anthesis stress (irrigation skipped at anthesis stage) and I3 = post-anthesis stress (irrigation skipped at post-anthesis stage). Potassium was applied at four different rates, i.e., Ko = 0, K1 = 50, K2 = 100 and K3 = 150 kg ha-1. The results revealed that water stress at pre- and post-anthesis stages significantly reduced plant height, head diameter, number of achenes, oleic acid contents, and phosphorus (P) uptake. However, pre-anthesis stress improved linoleic acid contents. Treatment IoK3 (stress-free with 150 kg ha-1 K) was optimum combination for 1000-achene weight, biological and achene yields, oil contents, protein contents, and N and P uptake. Results indicated that a higher amount of K and irrigation resulted in higher yield, whereas yield and yield components decreased with early-stage water stress. Nevertheless, potassium application lowered the impacts of waters stress compared to no application. Keeping in view these results, it is recommended that sunflower must be supplied 150 kg ha-1 K in arid and semi-arid regions to achieve higher yield and better seed quality.

Health risk assessment of heavy metals via consumption of dietary vegetables using wastewater for irrigation in Swabi, Khyber Pakhtunkhwa, Pakistan.

Health assumptions to the population due to the utilization of contaminated vegetables have been a great concern all over the world. In this study, an investigation has been conducted to ascertain metal concentrations in the wastewater, soil and commonly consumed vegetables from the vicinity of Gadoon Industrial Estate Swabi, Khyber Pakhtunkhwa Pakistan. Physicochemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS) and total solids (TS) and heavy metals such as Pb, Cr, Cd, Ni, Zn, Cu, Fe, Mn were determined using Atomic Absorption Spectrophotometer (AAS). Moreover, possible health risks due to the consumption of vegetables have also been estimated. pH and TSS in wastewater were found to be higher than the permissible limit set by WHO (1996). These results revealed that Cr concentration in the wastewater was above the permissible limits of United States Environmental Protection Agency (USEPA) which may lead to a detrimental effect on soil quality deterioration, ultimately leading to food contamination. ANOVA analysis demonstrated a significant difference in soil samples for Pb, Cr, Cd, Ni, Zn and Cu at p ≤ 0.001, for Mn at p ≤ 0.05 while no significant difference was observed for Fe respectively. ANOVA analysis also exhibited the highest mean value for Pb, Cr, Cd and Zn in vegetables. A substantial positive correlation was found among the soil and vegetable contamination. The transfer factor for Cr, Pb, Zn, Mn, Ni, Cd and Cu was greater than 0.5 due to contamination caused by domestic discharges and industrial effluents. Health assessment via consumption of dietary vegetables revealed a higher level than the permissible limit (HRI > 1) for Pb and Cd in children and adults. Enrichment factor (EF) due to consumption of vegetables was found higher for Pb and Cr respectively. Based on the findings of this study, there would be a significant risk to the consumers associated with consumptions of vegetables being cultivated in Gadoon Industrial Estate area of district Swabi. Therefore, strict regulatory control measures are highly recommended for the safety of vegetables originated from the study area.