On the Growth of Zea mays1
Milanie Joy S. Baradi
BIO 30 Section S-1L
October 10, 2011
1A scientific paper submitted in partial fulfillment of the requirements in Biology 30 laboratory under Professor Neilyn O. Villa, 1st semester, 2011-2012.
To determine the effects of gamma radiation in inducing mutation on the growth of corn (Zea mays), an experiment using corn seeds exposed in to different rate of radiation (0kr, 10 kr, 30 kr, and 50 kr) was done. Four treatments were prepared using 10 seeds from each of the following different radiation rates. The seeds were planted and were observed for seven weeks. The percent germination and mortality rate, as well as the height (in cm) were obtained. Results showed that the control obtained the highest germination rate and average plant height while the lowest was obtained by the treatment which used the highest irradiation rate (50 kr). From the results it could be concluded that increasing the radiation rate can inhibit the growth in terms of height and lower the percent germination by inducing mutation. As the exposure of the corn seeds to gamma radiation increases, the more it reduces the corn’s potential for optimum growth and development.
Mutation is defined as the change in the DNA sequence of a gene in an organism that is essentially heritable and permanent. It occurs when the genetic message carried by the gene is altered or damaged (Mendioro et al., 2010). Mutation can either be spontaneous or induced. One way to induce mutation is through the use of mutagens. Mutagens are natural or human made agents (chemical or physical) which can alter the DNA sequence structure of organisms. Examples of mutagens include different types of chemicals and radiation. The use of gamma rays, a type of radiation classified under the ionizing radiations, is commonly used in various experiments in inducing mutation. The use of gamma radiation has diverse effects on the behavior and structure of a chromosome. It can also cause adverse effects on the physiological and biochemical processes of plants. Exposing seeds in high dosage of gamma rays can cause detrimental effects in the growth and germination rate. Exposure of a seed in higher dose of radiation can cause disturbances on some of its important biological processes such as the water exchange and enzyme activity (Stoeva et al., 2001) and protein synthesis (Xiuzher, 1994). The changes on the morphology, structure and function depends on the strength of the gamma irradiation stress. The parameters used in assessing the effectiveness of radiation in inducing mutations include the percent rate of seed germination and survival of the seedlings. The study aimed to determine the effect of induction of mutation by gamma radiation on the growth of corn (Zea mays). The specific objectives were: 1. to identify the effect of increasing strength of gamma rays on growth of corn (Zea mays) in terms of height, percent germination, and percent mortality; 2. to explain the possible reasons behind the observed effect of radiation on corn.
MATERIALS AND METHODS
In order to determine the effects of radiation on the growth, percent germination and percent mortality of corn (Zea mays), forty seeds were used into four different treatments. The first ten seeds were used as the control (0kr) while the other thirty were irradiated with gamma radiation using different intensities (10kr, 30kr and 50kr). A plot was prepared. Four hills were made in the plot where seeds will be planted. The seeds were planted 5 cm apart on a hill, with each hill representing a specific treatment. The hills were labeled accordingly. For seven weeks, the corn plants were observed. The seed germination (germination time and percent germination) and morphological changes of the vegetative parts of the plant was noted. After weeks...