Germination and emergence of corn (Zea mays, L) as a function of soil physical parameters

Tesis para obtener el grado de Magister Scientiae en Soil Science, de la Oregon State University, en diciembre de 1988Rates of germination and emergence of corn were measured as influenced by soil physical parameters using blotter paper and a sandy loam soil as growth media. The corn seeds used were a hybrid of Funk's (DJ7xLH93). Experimental conditions were soil temperature of 20°C, 25°C, 30°C, and 35°C, soil water potential of -33, -100, -500, and -1000 kPa, soil bulk density 1.29 and 1.36 Mg/m³ and seeding depth of 3 and 7 cm. For the germination experiment seeds were put in contact with polyethylene glycol at solution concentrations to produce the desired water potentials. Treatment temperatures were maintained in a growth chamber and germination was evaluated every twelve hours. The number of hours required to obtain 50 and 80% germination was significantly increased by lowering either temperature or water potential. Although significant interactions were measured, temperature and water potential affected germination in different ways. Time to attain 80% of germination decreased as temperature increased until the optimum of 30°C was reached. Decreased osmotic potential levels progressively delayed and reduced germination. Time to germination increased greatly below -500 kPa. For emergence experiments seeds were planted in soil packed in covered containers which were placed in a growth chamber. Effects of soil temperature, soil water potential, bulk density, and seeding depth were evaluated. Bulk densities of 1.29 and 1.36 Mg/m³ , were achieved by no compaction and compaction. The two seeding depth were 3 and 7 cm. Time needed for emergence was influenced by soil temperature more than by any other variable. The time for emergence decreased progressively with lowering of soil water potential, lowering temperature or with increase in seeding depth. No significant differences resulted from increasing bulk density. In both the germination and emergence experiments, changes in temperature were more important than changes in water potential at high water potential. However this relation was reversed at water potentials lower than -500 kPa, where changes in water potential were more important than changes in temperature. The minimum time for both germination and emergence occurred at 30°C, at all water potentials. Effect of seeding depth was more important than effect of bulk density for time to emergence. Increases in time were between 20-30% as the seeding depth increased from 3 to 7 cm. Compaction began to limit seedling emergence at 1.44 Mg/m³.EEA Hilario AscasubiFil: Sanchez, Ramon Mauricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; Argentin