Nickel in Environment and Plant Nutrition: A Mini Review

Nickel (Ni) with iron forms the inner core of earth and is ranked seventh element responsible for causing health hazards and 9th in environmental degradation. Nickel is omnipresent. It is in air, water, plant foods and easily gets in the living bodies. Nickel is recently added as an essential plant micronutrient. It is a constituent of enzyme urease and is now known to be involved in several plant physiological processes including nitrogen metabolism, water relations, germination, photosynthesis, growth and senescence. It is present in soil, water systems, industrial effluents, fertilizer and manures in fairly good amounts to meet the requirements of crop plants. It is more known for its toxicity than for its deficiency. Nevertheless, there are Ni deficient soils and Ni fertilization has helped the crop plants. Most of the studies on Ni have been in pot-cultures and solution cultures. When required foliar application of Ni as nickel sulphate is preferred..

Growth and Chlorophyll Content of Canola Plants Supplied with Urea and Ammonium Nitrate in Response to Various Nickel Levels

Both the beneficial and the adverse effects of various nickel level supplements on growth and chlorophyll content of canola plants were evaluated while either urea or ammonium nitrate was supplied as the sole N source in the nutrient solutions. This study was arranged in completely randomized with three replications. Treatments included nutrient solution cultures containing urea and ammonium nitrate at the rate of 84 mg N L-1 separately as nitrogen sources with four nickel levels as NiSO4.6H2O at the rates of 0, 0.01, 0.05 and 0.1 mg Ni L-1. Plants were allowed to grow for 6 weeks then leaves chlorophyll content and shoots and roots fresh and dry weight were determined. Both plant growth and leaves chlorophyll content of the urea-fed plants increased significantly with the increase in nickel content up to 0.1 mg Ni L-1. However, root fresh and dry weight increased up to 0.01 mg Ni L-1 and started to decrease with further increase in solutions nickel content. Nickel did not affect these parameters with plants supplied with ammonium nitrate significantly. In these plants, the optimum nickel level for shoot growth and leaves chlorophyll content was 0.05 mg L-1 and for root fresh and dry weight was 0.01 mg Ni L-1. Further increase in Ni concentration reduced growth. As a whole, plants received urea plus nickel performed better than those received ammonium nitrate plus nickel.

Improving lucerne nodulation at low pH: contribution of rhizobial and plant genotype to the nodulation of lucerne seedlings growing in solution culture at pH 5

The effect of rhizobial strain and lucerne genotype on the nodulation of lucerne seedlings growing in solution cultures maintained at pH 5 was measured in two greenhouse experiments. Sinorhizobium strain SRDI291 increased the percentage of plants nodulated when compared with the commercial inoculant strain RRI128 (89% cf. 45% and 86% cf. 23% in the two experiments, respectively). Similarly, the mean number of nodules per nodulated plant (NNP) was greatest in the SRDI291 treatments (3.5 cf. 1.7 and 3.1 cf. 1.8). Plant genotype had fewer, but still significant effects on nodulation. Overall, lucerne genotype CRCSA29 had the highest percentage of plants forming nodules and most NNP (63% and 2.9); genotype L97a had the lowest (46% and 1.9). Greater variation in NNP occurred when the lucerne genotypes were inoculated with RRI128. Most notable was the better nodulation of CRCSA29 with 2.8 NNP compared with only 1.2 NNP for the two unselected genotypes (SARDI Ten and L97a). The lucerne genotypes typically had variable NNP, as exemplified in CRCSA29 inoculated with RRI128 where it ranged from 0–14, providing the opportunity for further plant selection. The work demonstrates that there remains substantial opportunity to increase the potential of lucerne to nodulate at low pH. Gains would appear to be most easily made by changing the strain of rhizobia that is used for inoculation.

Copper uptake in Typha latifolia as affected by iron and manganese plaque on the root surface

The effects of iron (Fe) and manganese (Mn) plaque on the accumulation of copper (Cu) in Typha latifolia L. were investigated under laboratory conditions in nutrient solution cultures. Seedlings with and without Fe plaque on their roots, induced with 15 or 60 µg·mL–1 Fe, were exposed to 0.04, 0.12, or 0.36 µg·mL–1 Cu solutions, and seedlings with and without Mn plaque, induced with 15 or 60 µg·mL–1 Mn, were exposed to 0.12 or 0.36 µg·mL–1 Cu solutions for 24 days, respectively. In all cases, the amount and proportion of Cu adsorbed on the root surface increased with a higher concentration of Cu in the solutions. In the presence of Fe or Mn, T. latifolia adsorbed more Cu and had a higher proportion of Cu on its roots, especially the roots with heavy Mn or Fe plaque. Although more Fe than Mn accumulated on the roots in the form of plaque, the Mn plaque adsorbed more Cu. The data suggest that root plaque can act as a Cu reservoir, depending on the amount of Fe or Mn on the roots and the amount of Cu in the environment.Key words: wetland plant, heavy metal uptake, cattail, iron plaque, manganese plaque.

A Comparison of Huckleberry (Vaccinium pahalae) and Bilberry (Vaccinium myrtillus) Shoot Culture Performance on Different Support Systems

In vitro cell cultures of huckleberry and bilberry are sources of phytochemicals for use as food colorants and bioactive chemopreventives. Shoot cultures provide a convenient, presterile source of explants for production of callus rich in extractable pigments or other chemicals. Efficient callus formation only occurs with good-quality shoots. In this study, liquid and gelled support systems were compared in terms of their effect on shoot growth. Gellan gum-based support resulted in excellent shoot proliferation and suitable shoot length for huckleberry cultures, whereas bilberry performed slightly better on agar and agar/gellan gum support. Bilberry had a more-rapid growth rate than huckleberry. Hyperhydricity was found with the use of rafts for both species. These shoot cultures have been used as vegetative explants for callus, and have produced vivid anthocyanins in solution cultures.