Maíz En La Fisiología Vegetal

University of Aristoteles Thessaloniki

Effects of heavy metals in the growth and chlorophylls of plant Zea mays



Thessaloniki 12-11-2012

Introduction
The objective of this practice is to evaluate the effect of copper and calcium in the growth of, young plants, of maize (Zea mays L.), from direct measurements of the length of the stem and root, and the extent of the amount ofchlorophyll in the shoots of each of the treatments. A Zea mays is an annual graminea plant native of America introduced in Europe in the seventeenth century. It´s currently the cereal with the highest volume of production in the world, surpassing wheat and rice. The importance of a deeper knowledge of the different characteristics of the growing of this specie, lies in is one of the most used cereals inthe world, since it use like food, 7000 BC, and other more recent uses for example as bioenergy source. (1)
Importantly not only the climate is critical to the production of corn, drought conditions and soil salinity also limit productivity (2). Within the classification of corn, according to tolerance of salinity, is a sensitive culture, being severely affected, even at low salt concentrations(3), it´s therefore necessary to determine the optimal margins to have the ideal growth (4).Respect to its physiology say that is a plant who needs long nights, and blooms with a certain number of days with temperatures above 10 º C (3).
There is increasing evidence that Ca2+ plays an important role in growth regulation in plant (7). It is an essential plant macronutrient that plays key roles incell wall and membrane structure. Furthermore calcio ions (Ca2+) act as secondary messengers for many signals. The active absorption of Ca by vacuolated maize roots makes this tissue ideal for further investigation of the basic characteristics of Ca2+ uptake (9). As we will explain in the discussion point, there is evidence that such a Ca-Cu imbalance could lead to disturbances in photosynthesis(8). Since this is true for such remote organism as Zea, it may be concluded that regulation of cytoplasmic pH and free Ca 2 + are interrelated (6).
Copper ions in the soil solution as Cu + or Cu2 + are absorbed by plant roots and soluble copper complexes. It is part of several enzymes that influence photosynthesis and carbohydrate metabolism and nitrogen.  Most of the copper in the plant islocated in the chloroplast, corresponding to about 50% plastocyanin, a non-enzymatic protein, and primary electron donor photosystem I in the electron transport chain of the photosynthesis.
It is not very mobile in plants, but some Cu can be taken from old leaves to new. The normal level of Cu in plants is in the range of 5 to 20 ppm. At these levels are observed a feature that help the plant todevelop in the best conditions, stimulates the production of grains, very important for the formation of root nodules, and regulates the transport and photosynthetic electro-catalytic functions essentially. Copper deficiency in young leaves leads to some chlorosis and leaf elongation. Excess copper, especially in acidic media, can be toxic; producing a yellowing of young leaves, Due to high copperaccumulation in the roots is damage to the cell membrane.
The plant tolerance to copper toxicity is varied. Factors such as the ability to absorb less copper soil solution to exude the copper that is in excess in the plant and / or transported in a form that does not affect the plant.
Materials and methods
To assess how affect the calcium and copper to the growth of maize plants (Zea mays), wascarried out the following process:
Plant material:
Before the start of the practices was promoted germination of the seeds (Zea mays) placed in a moistened filter paper, for few days.
Then the germinated seeds were planted in glasses with perlite, two per glass. To facilitate the evaluation of the development, was intended that the two seeds were placed in each glass were of similar size. Then we...