Vesicular Arbuscular Mycorrhizae-Mediated Uptake and Thanslocation of P and Zn by Wheat in Calcareous Soil

Vesicular-arbuscular mycorrhizal (VAM) fungi have been credited with improving the groWth and mineral nutrition of many host plants but these effects are moderated by soil factors and nutrient balance. The combined effects of VAM, Zn and P application on the growth and translocation of nutrients in wheat were investigated using a calcareous soil marginal in P and Zn concentrations. Wheat was grown in a growth chamber under various combinations of VAM, P and Zn with measurements done at heading stage and maturity.Vegetative dry matter accumulation was increased by P application and reduced by VAM treatments. Both P and VAM increased grain yield. Zinc concentration and uptake were generally reduced by P addition and VAM infection. There were no antagonistic effects of Zn on P acquisition in the plant. The role of VAM in enhancing the translocation of Zn and P from root to grain would be beneficial to seed setting and yield.

Efficiency of soil-applied ^(67)Zn-enriched fertiliser across three consecutive crops

A very small amount of applied zinc(Zn) is taken up by crops, resulting in low recovery by plants. Adding elemental sulphur to zinc oxide(ZnO) fertiliser could improve Zn solubilisation and exert a higher residual effect on crops than soluble Zn sources. We produced an isotopically labelled Zn-elemental sulphur fertiliser and evaluated its performance in comparison to traditional Zn sources during sequential crop cultivation. Three ^(67)Zn-labelled fertilisers,ZnO, zinc sulphate(ZnSO_(4)), and ZnO co-granulated with elemental sulphur(ZnOS^(0)), were soil applied, and their contributions to the uptake of Zn by three consecutive crops, wheat, ryegrass, and corn, were assessed in a 294-d pot experiment. The contributions of Zn fertilisers followed the order: ZnSO_(4) > ZnO= ZnOS^(0). The relative contributions of Zn fertilisers were lower in the first crop than in the subsequent crops. The overall recovery of applied Zn by the three crops was higher for ZnSO_(4) than for ZnO and ZnOS^(0), reaching 1.56%, 0.45%, and 0.33% of the applied Zn, respectively. Zinc recovery by plants was very low, regardless of the source of Zn. Adding elemental sulphur to ZnO did not increase its effectiveness up to 294 d after application. Fertiliser contribution was higher for the subsequent crops than for the initial crop, indicating the importance of assessing the residual effects of Zn fertilisers.

Partial Relief of Drought-Stressed Fennel(Foeniculum vulgare Mill.) in Response to Foliar-Applied Zinc

Few attempts have been made to explore the effect of Zn fertilization on the performance of medicinal plants in general and fennel in particular, under adverse conditions. This study was conducted to examine the efficacy of zinc (Zn) in correcting physiological responses of fennel to water deficit. Twelve field-grown fennel genotypes were subjected to two levels of irrigation (irrigation after 25%–35% and 75%–85% depletion of available soil water) and two levels of foliar-applied Zn (0 and 4 g kg −1 ). Water deprivation had significant effects on all characteristics;i.e., in contrast to seed essential oil concentration, harvest index, and superoxide dismutase (SOD) and catalase activities, it led to decreases in the rest of the attributes. Varietal differences in response to drought were meaningful for most of the traits. Genotypic variations for dry mass and seed yield were consistent with differences among the genotypes in leaf water potential, relative water content, proline concentration, and chlorophyll concentrations. Zinc led to significant increases in all physiological attributes, including activation of antioxidant defense responses manifested in ascorbate peroxidase and SOD activities and carotenoid concentration. The Zn-effect tended to be more notable in drought-stricken fennel plants in a majority of the traits. Based on our findings, Zn could be considered an effective micronutrient for ameliorating, at least in part, the stressful effects of water deficit on fennel.