Charecterization of Summer Dormancy in Tall Fescue.

Summer dormancy is an important drought adaptation trait that is poorly understood in the cool season perennial grass tall fescue (Festuca arundinaceum, 2n = 6x = 42).  This trait is often confused with drought tolerance as both the traits have similar symptoms.  For a clear understanding of the mechanism and the factors governing it, summer dormancy should be characterized and separated from the confounding symptoms of drought tolerance.

 

            In this investigation, we studied summer dormancy in three tall fescue genotypes of Mediterranean origin, R4364 (summer active), Agrfa103-2 (Obligate summer dormant), and Agrfa103-4 (semi active) under four growth chamber conditions [Two levels each of day length (long day and short day) and air temperature (high temperature and low temperature)].  In each growth chamber, two levels each of vernalization (vernalized and non vernalized), and soil moisture (well watered and sparsely watered) are studied in all the three genotypes.  Notes was taken on various phenotypic traits like number of tillers, number of leaves, leaf length, leaf growth, percentage of greenness, and moisture content of leaves that indicate plant growth.  All the treatments within each growth chamber were randomized, and replicated thrice in a split plot design.

 

            Preliminary results show significant differences between the genotypes within each growth chamber.  Well watered plants in each genotype had higher trait means than the sparsely watered plants although the obligate summer dormant genotype had low means compared to the active and semi active genotypes.  In order to confirm the role of day length and temperature in inducing summer dormancy, this experiment has to be repeated at least one more time, although, between the four growth chamber conditions least growth was seen under long day and high temperature conditions.