INDUCED PASSIVE HEATING ON THE EMERGENCE, EARLY GROWTH AND PHOTOCHEMICAL RESPONSES OF SEEDLINGS OF NATIVE MAIZE (ZEA MAYS L.) GENOTYPES FROM WARM-DRY, TEMPERATE, AND HOT AND HUMID CLIMATES

Abstract

The majority of research on the effects of climate change on maize has concentrated on yield, with only a few studies focusing on seedling emergence and growth. Warmer temperatures predicted as a result of climate change will have an impact on seedlings emergence and growth. An experiment was carried out with induced passive heat with the objective of simulating the increase in temperature in emergence, initial growth and photosynthetical parameters of native genotypes of maize from three different agro-ecological zones (warm-dry, temperate, and hot and humid) climates of San Luis Potosí, México. Two different environments, Open Top Chambers (OTC) and control, were used as treatment and two genotypes for each agro-ecological zone were used. A total of 100 seeds were used in a random design with factorial arrangement for each genotype and environment (OTC and control). Abiotic variables (mean daily temperature, minimum and maximum daily temperature and the accumulated heat units) were determined and compared between the two environments and confirmed that the OTC increased temperatures and heat units. The percentage and velocity of seedling emergence and photochemical quenching (qP) were negatively affected by the effect of induced heat while the rate of growth of plants was accelareted and its plant height was increased. These results reveal dependence on the adaptation of the native genotypes. According to seedling emergence and growth, genotypes from less stress conditions (hot and humid (Huasteca)) were most affected while those from places with major variations in temperature condicions (warm-dry and temperate (Altiplano and Media respectively)) were not. We concluded the effect of induced heat diminish the seedling emergence and photochemical quenching while the growth benefited. Keywords: Climate change; Heat; Open top chamber; Temperature; Zea mays seedling