Abstract
Zinc (Zn) is one of the eight essential micronutrients. It is needed by plants in small amounts, but yet crucial to plant development. A solution culture experiment was conducted to study the variation in growth, water relations and anatomy of roots, stems and leaves of Phaseolus vulgaris cv. contender treated with 1, 200, 400, 600, 800, 1000and 1200 mMZnSO4. Maximum significant deplete in parameters of growth (Length of root and shoot; fresh and dry weights, relative growth rate; No of leaves and leaf area), stomatal index and rate of transpiration was observed with, 200, 400, 600, 800, 1000and 1200 mM ZnSO4. These effects were improved by the addition of Ca2+than the addition of glutathione at 10 mM. Moreover, there were a significant increase at low concentration (1mM) treatment. Width of root, width of cortex and width of vascular bundles were increase with increasing Zn concentrations either alone or in combination with glutathione >Ca (NO3)2. For stem, the No of vascular bundles were decreased with increase in Zn concentration alone and with Ca (NO3)2, meanwhile increase with glutathione. Width of cortex and No of its rows were decrease with increase Zn concentrations. For leaves, the thickness of leaf blade, mid rib and vascular bundle were increase with increase the Zn concentrations alone, On other hands, they records a significant decrease in combination of Zn with Ca(NO3)2 or glutathione . In general, an increase in total uptake of zinc with increasing the concentration of Zn in all treatments. However, Ca (NO3)2 decrease these amounts than glutathione.
Highlights
IntroductionThe term "heavy metal" commonly refers to metals with a specific weight in excess of 5 g / cm or anatomical number in excess of 20
Effect of Zn Treatments on Plant Growth and Water Relations of Phaseolus Vulgaris Different growth parameters of intact Phaseolus plants as shown in figure 1 and; number of stomata, stomatal area, relative water contents and rate of transpiration as shown in table 1 showed a significant increase in growth at low concentration ( 1mM )
Since Zn is required for the synthesis of tryptophan (Brown et al, 1993; Alloway, 2004), which is a precursor of IAA, this metal has an active role in the production of auxin, an essential growth hormone (Brennan, 2005; Tsonev and Lidon 2012)
Summary
The term "heavy metal" commonly refers to metals with a specific weight in excess of 5 g / cm or anatomical number in excess of 20. Such properties are our significance for biological effects, yet the heavy metals contain essential nutrients, beneficial elements and elements that are not known to be active in humans at the present stage of science. Toxicity is not an exclusive aspect of heavy metals listed elements. Among the myriad of heavy metals zinc occupies the prominent position, since it plays a vital role in the growth and development of plants. Zinc deficiency or toxicity is not common; both negatively impact crop growth and performance. Any deficiency or toxicity must be addressed prior to irreversible crop damage
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