Investigation of the effect of temperature on in-vitro pollen germination, pollen tube length and pollen viability in maize (Zea mays L.)

Corn (Zea mays L.) is a global product that is the most produced in the world and is used in a wide range from our homes to the industrial area. Like all living things, corn tries to adapt itself to the conditions in an ecosystem in order to exist. These living conditions are not always as suitable as desired. Under these conditions, it is inevitable that the development levels of living things will deteriorate and negative results will occur in the ecosystem. Especially climate changes caused by global warming cause weakening in the development stages along with the stress it creates in the development processes of corn. Stress types in plants are expressed under two headings as biotic stress and abiotic stress according to their formation methods. Abiotic stress factors can be counted as environmental factors such as heat, cold, salinity, drought, excess water, radiation, some chemicals, and drought. Biotic stress factors can be counted as living factors such as viruses of biological origin, insects, bacteria and herbivores. In this thesis study, it was aimed to observe the changes in pollen viability rates, pollen germination rates and pollen tube lengths in Zea mays L. (corn) plant under in vitro conditions in order to deeply investigate the effects of increasing temperature values on corn plant pollen. Corn seeds selected for the application were prepared in vitro and planted. Corn seedlings were allowed to grow and corn pollen was collected in a 2-month period. The collected corn pollen was kept in the oven at 5 ⁰C, 10 ⁰C, 20 ⁰C, 30 ⁰C, 40 ⁰C by preparing preparations in vitro. Pollen viability rates, pollen germination rates and pollen tube lengths were determined to determine the effects of changing temperature values on corn plant pollen performance. The "cumulative stress response index" (CSRI) test was used to define the effects of these stress factors on pollen. The responses of the corn plant to heat stress during its developmental stages were analyzed. The temperature values required for the optimum development of corn were determined. Research findings showed that pollen viability, germination percentages and pollen tube lengths of corn pollen decreased at high and low temperatures compared to the control group. It was clearly revealed that the pollen development process was negatively affected at temperatures outside the optimum range. The results of this study provide important information for the effects of heat stress in maize breeding. Knowing the effects of global warming on maize pollen structure will enable us to predict the fertilization success of pollen in the field environment and to reduce its negative effects. In this way, it will be possible to foresee the negative results caused by climate change in maize breeding.