EVALUATION OF SPAD CHLOROPHYLL IN SPRING WHEAT GENOTYPES UNDER DIFFERENT ENVIRONMENTS

Wheat is an important food crop. Its production is limited by multiple environmental stresses, especially terminal heat stress. High temperature and drought are the main stresses affecting wheat production in the Mediterranean region. Hence, the chlorophyll content in leaves reflects photosynthetic activity and the yield potential of wheat plants. So, the aim of this study was to evaluate SPAD (Soil Plant Analysis Development) chlorophyll meter readings and their relationships with the grain yield of spring wheat growing in different environments, and to examine the physiological responses to environmental stress at different growth stages. Sixteen spring wheat genotypes were grown under two temperature (cool and warm) and two moisture (rain-fed and irrigated) regimes during the 2011/2012 growing season in two locations in Turkey (Adana and Diyarbakir). There were significant genotypic variations in SPAD values under all conditions. There was a significant positive correlation between third-leaf SPAD values and grain yield in the cool-climate conditions at Adana. There was a significant positive relationship between flag-leaf SPAD values at the heading stage and grain yield under cool-climate conditions in Diyarbakir, while the relationship between SPAD values and grain yield was negative under warm-environment conditions. The SPAD values were more strongly affected by location and heat stress than by drought stress. Regarding to the range of SPAD values within each genotype was relatively stable. Together, these results showed that SPAD values can be used as an indicator of grain yield in spring wheat, providing that the measurements are taken at appropriate stages at each location.