The essential and beneficial roles of nickel In growth of soybean and wheat plants

Nickel (Ni), which is known to be the cofactor of urease, was the last element to be included in the list of essential micronutrients for higher plants. Although the Ni requirement of plants is very low, Ni deficiency was documented to occur under field conditions. However, most of the studies on plant Ni nutrition were conducted in hydroponics and focused on urea metabolism. In order to investigate the essential and beneficial roles of Ni in plant growth, several nutrient solution and soil culture studies were conducted on two major crops, namely soybean and wheat, under growth chamber and greenhouse conditions. Nickel deficiency reduced the seed yield in nitrate-fed soybean and caused impaired growth and toxicity symptoms upon foliar urea applications. Moreover, Ni deficiency resulted in physiological nitrogen (N) deficiency and reduced the N uptake and N use efficiency (NUE) of urea-fed plants. Using high-Ni seeds was a highly effective alternative to external Ni supply for alleviating the problems caused by urea. In wheat, soil and/or foliar applications of Ni improved the grain yield and NUE under ample N supply, indicating that Ni may be beneficial at levels much higher than required to fulfill its essential roles, depending on the conditions. Furthermore, foliar Ni applications were shown to provide protection against sublethal glyphosate, which can cause developmental abnormalities and dramatic yield losses in wheat. The use of Ni as a micronutrient may have great impacts on agricultural productivity, NUE and crop tolerance to glyphosate drift. These effects should be further investigated under field conditions

Foliar nickel application alleviates detrimental effects of glyphosate drift on yield and seed quality of wheat

Glyphosate drift to nontarget crops causes growth aberrations and yield losses. This herbicide can also interact with divalent nutrients and form poorly soluble complexes. The possibility of using nickel (Ni), an essential divalent metal, for alleviating glyphosate drift damage to wheat was investigated in this study. Effects of Ni applications on various growth parameters, seed yield, and quality of durum wheat (Triticum durum) treated with sublethal glyphosate at different developmental stages were investigated in greenhouse experiments. Nickel concentrations of various plant parts and glyphosate-induced shikimate accumulation were measured. Foliar but not soil Ni applications significantly reduced glyphosate injuries including yield losses, stunting, and excessive tillering. Both shoot and grain Ni concentrations were enhanced by foliar Ni treatment. Seed germination and seedling vigor were impaired by glyphosate and improved by foliar Ni application to parental plants. Foliar Ni application appears to have a great potential to ameliorate glyphosate drift injury to wheat

Effects of seed nickel reserves or externally supplied nickel on the growth, nitrogen metabolites and nitrogen use efficiency of urea- or nitrate-fed soybean

Nickel (Ni) has a critical role in the urea metabolism of plants. This study investigated the impact of seed Ni content along with external Ni supply on the growth, various nitrogen (N) metabolites and N use efficiency (NUE) of soybean plants. Soybean plants raised from Ni-poor or Ni-rich seeds were grown in nutrient solution with or without external Ni supply and fed with either urea or nitrate as the sole N source. The changes in growth, leaf chlorophyll levels, Ni and N concentrations of different plant parts, tissue accumulation of various N metabolites and N uptake of soybean as well as NUE and its components were examined. Nickel starvation reduced the shoot biomass of urea-fed plants by 25 % and the leaf chlorophyll levels by up to 35 %, but nitrate-fed plants were unaffected. Visual toxicity symptoms were not observed in urea-fed plants. Under urea supply, Ni-deficient plants had lower levels of total N, protein and free amino acids in various organs. Root uptake of urea was severely depressed in Ni-deprived plants. Availability of Ni did not have any effect on the NUE of nitrate-fed plants, whereas its deficiency reduced the NUE of urea-fed plants by 30 %. The growth and N nutritional status of urea-fed soybean were significantly improved by high seed Ni reserves as well as external Ni supply. Adequate Ni supply is required for maximizing the growth, root uptake of urea and NUE of urea-fed plants. Seed Ni reserves contribute significantly to the Ni and thus N nutritional status of soybean

Effect of nitrogen on uptake, remobilization and partitioning of zinc and iron throughout the development of durum wheat

Deficiencies of zinc (Zn) and iron (Fe) are global nutritional problems and caused most often by their limited dietary intake. Increasing Zn and Fe concentrations of staple food crops such as wheat is therefore an important global challenge. This study investigated the effects of varied nitrogen (N) and Zn supply on the total uptake, remobilization and partitioning of Zn, Fe and N in durum wheat throughout its ontogenesis. Plants were grown under greenhouse conditions with high or low supply of N and Zn, and harvested at 8 different developmental stages for analysis of Zn, Fe and N in leaves, stems, husks and grains. The results obtained showed that the Zn and Fe uptake per plant was enhanced up to 4-fold by high N supply while the increases in plant growth by high N supply were much less. When both the Zn and N supplies were high, approximately 50% of grain Zn and 80% of grain Fe were provided by post-anthesis shoot uptake, indicating that the contribution of remobilization to grain accumulation was higher for Zn than for Fe. At the high N and Zn application, about 60% of Zn, but only 40% of Fe initially stored in vegetative parts were retranslocated to grains, and nearly 80% of total shoot Zn and 60% of total shoot Fe were harvested with grains. All these values were significantly lower at the low N treatment. Results indicate that N nutrition is a critical factor in both the acquisition and grain allocation of Zn and Fe in wheat

Improved nitrogen status enhances zinc and iron concentrations both in the whole grain and the endosperm fraction of wheat

This study was conducted to assess the role of increasing N supply in enrichment of whole grain and grain fractions, particularly the endosperm, with Zn and Fe in wheat. The endosperm is the most widely consumed part of wheat grain in many countries. Plants were grown in the greenhouse with different soil applications of N and Zn and with or without foliar Zn spray. Whole grain and grain fractions were analyzed for N, P, Zn and Fe. Increased N supply significantly enhanced the Zn and Fe concentrations in all grain fractions. In the case of high Zn supply, increasing N application enhanced the whole grain Zn concentration by up to 50% and the endosperm Zn by over 80%. Depending on foliar Zn supply, high N elevated the endosperm Fe concentration up to 100%. High N also generally decreased the P/Zn and P/Fe molar ratios in whole grain and endosperm. The results demonstrate that improved N nutrition, especially when combined with foliar Zn treatment, is effective in increasing Zn and Fe of the whole grain and particularly the endosperm fraction, at least in the greenhouse, and might be a promising strategy for tackling micronutrient deficiencies in countries where white flour is extensively consumed

Contributions of root uptake and remobilization to grain zinc accumulation in wheat depending on post-anthesis zinc availability and nitrogen nutrition

Background and aims Whether root Zn uptake during grain filling or remobilization from pre-anthesis Zn stores contributes more to grain Zn in wheat is subject to an on-going debate. This study investigated the effects of N nutrition and post-anthesis Zn availability on the relative importance of these sources. Methods Durum wheat plants were grown in nutrient solution containing adequate Zn (0.5 mu M) and three different N levels (0.5; 1.5; 4.5 mM). One third of the plants were harvested when they reached anthesis. One half of the remaining plants were grown to maturity with adequate Zn, whereas the Zn supply to the other half was discontinued at anthesis. Roots, straw and grains were harvested separately and analyzed for Zn and N. Results Depending on the N supply, Zn remobilization from pre-anthesis sources provided almost all of grain Zn when the Zn supply was withheld at anthesis; otherwise up to 100 % of grain Zn could be accounted for by Zn taken up post-anthesis. By promoting tillering and grain yield and extending the grain filling, higher N supply favored the contribution of Zn uptake to grain Zn accumulation. Conclusion Remobilization is critical for grain Zn accumulation when Zn availability is restricted during grain filling. However, where root uptake can continue, concurrent Zn uptake during grain development, favored by higher N supply, overshadows net remobilization

Willow (<i>Salix babylonica</i>) Extracts Can Act as Biostimulants for Enhancing Salinity Tolerance of Maize Grown in Soilless Culture

Salinity negatively affects agricultural production by reducing crop growth and yield. Botanical biostimulants can be used as innovative and sustainable tools to cope with abiotic stress. In this study, salicylic acid (SA) (25 µM) and willow leaf (WL) (0.1 and 0.2%) and bark (WB) (0.1 and 0.2%) extracts were applied as plant-based biostimulants to hydroponically grown maize in the absence and presence of salinity stress (60 mM NaCl). The hormone-like activity and mineral composition of willow extracts were analyzed, and the effects of willow extracts on growth parameters, chlorophyll content, antioxidative enzyme activities, protein levels and mineral nutrient concentrations of maize plants were measured. Within the tested biostimulant applications, 0.2% WB, 0.1% WL and 0.2% WL gave the most promising results, considering the stress alleviating effects. The shoot biomass was increased up to 50% with 0.1% WL treatment and Na+ uptake was reduced with biostimulant applications under saline conditions. Under stress, the protein concentrations of maize leaves were enhanced by 50% and 80% with high doses of WB and WL applications, respectively. Results indicate that willow tree prunings can be valuable bio-economy resources, and aqueous extracts prepared from their leaves and barks can be used as effective and eco-friendly biostimulants

Foliar Nickel Application Alleviates Detrimental Effects of Glyphosate Drift on Yield and Seed Quality of Wheat

Glyphosate drift to nontarget crops causes growth aberrations and yield losses. This herbicide can also interact with divalent nutrients and form poorly soluble complexes. The possibility of using nickel (Ni), an essential divalent metal, for alleviating glyphosate drift damage to wheat was investigated in this study. Effects of Ni applications on various growth parameters, seed yield, and quality of durum wheat (Triticum durum) treated with sublethal glyphosate at different developmental stages were investigated in greenhouse experiments. Nickel concentrations of various plant parts and glyphosate-induced shikimate accumulation were measured. Foliar but not soil Ni applications significantly reduced glyphosate injuries including yield losses, stunting, and excessive tillering. Both shoot and grain Ni concentrations were enhanced by foliar Ni treatment. Seed germination and seedling vigor were impaired by glyphosate and improved by foliar Ni application to parental plants. Foliar Ni application appears to have a great potential to ameliorate glyphosate drift injury to wheat

Biofortification of durum wheat with zinc through soil and foliar applications of nitrogen

ABSTRACT 2 Increasing zinc (Zn) concentration of cereal grains is a global challenge to alleviate Zn 3 deficiency-related health problems in humans caused by low dietary Zn intake. This study 4 investigated the effects of soil- and foliarly-applied nitrogen (N) and Zn fertilizers on grain Zn 5 accumulation of durum wheat (Triticum durum) grown on a Zn-deficient soil. In addition, 6 localization of Zn and protein within durum wheat grain was studied by using Bradford 7 reagent for protein and dithizone (diphenyl thiocarbazone) for Zn. Grain Zn concentration was 8 greatly enhanced by soil or foliar applications of Zn. When Zn supply was adequately high, 9 both soil and foliar N applications improved grain Zn concentration. Consequently, there was 10 a significant positive correlation between grain concentrations of Zn and N, when Zn supply 11 was not limiting. Protein and Zn staining studies showed co-localization of Zn and protein 12 within the grain, particularly in the embryo and aleurone. Results indicate that N and Zn 13 fertilization have a synergistic effect on grain Zn concentration. Possibly, by affecting the 14 levels of Zn-chelating nitrogenous compounds and/or the abundance of Zn transporters, 15 increasing N supply contributes to grain Zn concentration, suggesting that nitrogen 16 management can be an effective agronomic tool to improve grain Zn concentration