EFFECT OF WATERING REGIME ON YIELD, WATER USE AND LEAF CONDUCTANCE OF SEVEN FESTUCA SPECIES WITH CONTRASTING LEAF RIDGING

Abstract

SummarySeedlings of seven Festuca species with contrasting leaf surface morphology were grown in pots with three different watering regimes to simulate full irrigation, intermittent soil moisture stress or prolonged soil moisture stress.When harvested at a similar growth stage, plants subjected to the greatest stress had the least shoot dry matter. Differences between treatments were greatest in the fastest growing plants, e.g. F. arundinacea cv. S.170. At harvest, mean transpiration rate was lowest in plants from the least stressed treatment and in species with the flattest leaf surfaces e.g. F. drymeja and F. gigantea. Whether or not allowance was made for the effect of the convolutions of the leaf surfaces in increasing effective leaf surface area, the ranking of the species for transpiration rate per unit leaf area under well watered conditions was the same.Overall water use efficiency (WUE) was greatest in plants subjected to prolonged soil moisture stress (383 mg shoot dry matter per 100 g of water transpired) and least in those which were intermittently stressed (301 mg per 100 g). WUE was also greater for the flatter leaved species, the greatest being for F. gigantea (437 mg per 100 g) and least for F. scariosa (275 mg per 100 g). These variations in water use efficiency were not closely related to daily maximum stomatal conductance or to stomatal density of the leaves.WUE was not highly correlated with any of the other parameters measured. At best, 46 % of the variation was associated (negatively) with the final rate of transpiration which in turn was closely correlated (positively) with the degree of adaxial leaf surface ridging.