ISHS Acta Horticulturae 726: IV International Symposium on Pistachios and Almonds
CRITICAL TEMPERATURES AND MACRO AND MICROSCOPIC DEVELOPMENT LEVELS OF CHILLING INJURY IN PISTACHIO FLOWERS OF TWO MAIN COMMERCIAL CULTIVARS |
| Author: | Y. Gholipour |
| Keywords: | pistachio, chilling injury, critical temperatures |
| Abstract:
Determining the critical temperatures and development of early-spring chilling injury helps to apply the suitable and on-time methods to inhibit the related injuries. Therefore, a 2-year research project was performed in Ghazvini area. Two cultivars, “Ghazvini” and “Ohadi”, 5 thermal levels, +2, 0, -2, -4 and -6°C and three developmental stages, bud, blooming bud and flowers, were mentioned. Samples were put in a freezing chamber with precise temperature and humidity control, and the temperature was reduced in a rate of 2°C per hour. At each thermal level, 20 samples were taken out and injury was studied. Macro- and microscopic levels of injury development were mentioned. Injury levels were classified in three groups, changing the tissue color, browning and whole necrosis. The first was identified as a reversible injury, which could negatively affect the pollination, fertilization and fruit set process. Browning was determined as the injury level in which plant receives permanent and irreversible strain. Critical temperature was determined as -4°C at bud stage, -2 at blooming bud and +2 at flower. Decreasing temperature down to two more degrees (e.g. -6 °C at bud) would result in irreversible and serious injuries. Two studied cultivars did not show any significant differences as the viewpoint of critical temperatures at each stage. Therefore, the only parameter affecting their injury level was the phenology of blooming. During the experiment, a low temperature injury was recorded in the field condition. Climatic data and data extracted from orchard survey were studied and compared with experiment results. | |
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